2013 년이동및무선통신단기강좌 3GPP LTE(-A): Part II MAC & Network Jae-Hyun Kim

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1 2013 년이동및무선통신단기강좌 3GPP LTE(-A): Part II MAC & Network Jae-Hyun Kim Wireless Internet and Network Engineering Research Lab. School of Electrical and Computer Engineering Ajou University, Korea Contents Introduction Network Architecture User Plane Protocol Control Plane Protocol LTE-Advanced Features Release 12 Issues Summary 2 1

2 Introduction 3 Release of 3GPP specifications GSM/GPRS/EDGE enhancements Release 99 - W-CDMA Release 4 TDD Release 5 HSDPA, IMS Release 6 HSUPA, MBMS, IMS+ Release 7 HSPA+(MIMO, HOM etc.) ITU-R M.1457 IMT-2000 Recommendations Release 8 LTE, SAE Release 9 Small LTE/SAE enhancement Release 10 LTE-Advanced Release 11 Interconnection Release 12 WCDMA 최초상용화 WCDMA 국내상용화 LTE 최초상용화 LTE 국내상용화 4 2

3 3GPP Standards Version Released Information Release This and earlier releases specify pre-3g GSM networks Release Q1 Specified the first UMTS 3G networks, incorporating a CDMA air interface Release Q2 added features including an all-ip Core Network Release Q1 Introduced IMS and HSDPA Release 6 Release 7 Release 8 Release 9 Release 10 Release 11 Release Q Q4 Frozen Dec Frozen Dec Frozen Mar Frozen Sep / Some works are still in progress Stage 1 frozen Mar / In progress Integrated operation with Wireless LAN networks and adds HSUPA, MBMS, enhancements to IMS such as Push to Talk over Cellular (PoC),GAN (Generic Access Network) Focuses on decreasing latency, improvements to QoS and real-time applications such as VoIP. This speci fication also focus on HSPA+(High Speed Packet Access Evolution), SIM high-speed protocol and contact less front-end interface (Near Field Communication enabling operators to deliver contactless services lik e Mobile Payments), EDGE Evolution. LTE, All-IP Network (SAE). Release 8 constitutes a refactoring of UMTS as an entirely IP based fourth-g eneration network. SAES Enhancements, WiMaX and LTE/UMTS Interoperability LTE Advanced fulfilling IMT Advanced 4G requirements. Backwards compatible with release 8 (LTE). Multi-Cell HSDPA (4 carriers). Advanced IP Interconnection of Services. Service layer interconnection between national operators/ carriers as well as third party application providers (Content still open (as of October 2012).) 5 Network Architecture 6 3

4 Evolution of Network Architecture 7 Evolution Path of Core Network E-UTRAN(Evolved Universal Terrestrial Radio Access Network) S1 X2 NB : NodeB RNC : Radio Network Controller SGSN : Serving GPRS Support Node GGSN : Gateway GPRS Support Node enb : E-UTRAN NodeB agw : Access Gateway MME : Mobility Management Entity UPE : User Plane Entity 8 4

5 UMTS Architecture(Release-5) Radio Access Network (RAN) (UTRAN) CSCF 3G Core Network (CN) R-SGW External Network SS7 RNC HSS HLR Cx Mg CSCF Mr MGCF T-SGW Node B Iub Iur RNC Iu Gr SGSN Gn MRF Gi Gi GGSN Mc MGW PCM SS7 PSTN RNC : Radio Network Controller SGSN : Serving GPRS Support Node GGSN : Gateway GPRS Support Node CSCF : Call State Control Function MGCF : Media Gateway Control Function MRF : Multimedia Resource Function Gi(IP) Internet SS7 : Signal System No.7 R-SGW : Roaming Signaling Gateway T-SGW : Transport Signaling Gateway 9 Overall Architectural Overview EPS (Evolved Packet System) network elements Interface for data plane Interface for control plane E-UTRAN E-SMLC: Evolved Serving Mobile Location Centre GMLC: Gateway Mobile Location Centre Evolved Packet Core (EPC) HSS: Home Subscriber Server PCRF: Policy Control and Charging Rules Function 3GPP TS V E-UTRA and E-UTRAN; Overall description, June,

6 Core Network Elements Network Elements PCRF (Policy Control and Charging Rules Function) HSS (Home Subscriber Server) E-SMLC (Evolved Serving Mobile Location Centre) GMLC (Gateway Mobile Location Centre) Features Policy control decision making Controlling the flow-based charging functionalities in the PCEF (Policy Control Enforcement Function) which resides in the P-GW QoS authorization (QoS class identifier and bit rates) Contains users SAE subscription data such as EPS-subscribed QoS profile and any access restrictions for roaming Information about the PDNs to which the user can connect Identity of the MME to which the user is currently attached or registered Manage the overall coordination and scheduling of resources required to find the location of a UE attached to E-UTRAN Calculate the final location of UE based on the estimates it receives Estimate the UE speed and the achieved accuracy Contain functionalities required to support location services Send positioning requests to the MME and receives the final location estimates 11 Core Network Elements Network Elements P-GW (PDN Gateway) S-GW (Serving Gateway) Features IP address allocation for the UE QoS enforcement and flow-based charging according to the PCRF All user IP packets are transferred through the S-GW LMA (Local Mobility Anchor) when the UE moves between enode-bs Retains the information about the bearers when the UE is in idle state Temporarily buffers downlink data while the MME initiates paging of the UE to re-establish the bearers Collecting information for charging (the volume of data sent/rcvd) Mobility anchor for inter-working with GPRS and UMTS MME (Mobility Management Entity) Process the signaling between the UE and the CN (Core Network) (NAS: Non- Access Stratum) Bearer & Connection management Establishment, maintenance and release of the bearers Establishment of the connection and security between the network and UE 12 6

7 S Access Network Overall architecture E-UTRAN consists of enbs enbs are interconnected with each other by X2 interface enbs are connected by means of S1 interface to the EPC S1 interface supports a many-to-many relation between MMEs/S-GW and enbs S1 S1 S1 S1 S1 S5 X2 X2 S1 S1 3GPP TS V E-UTRA and E-UTRAN; Overall description, June, Access Network The enb hosts following functions RRM (Radio Resource Management) Radio Bearer Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs (scheduling) Processing user plane data IP header compression and encryption of user data stream AS security Selection of an MME at UE attachment when no routing to an MME can be determined from the information provided by the UE Forwarding of user plane data towards S-GW Measurement and measurement reporting configuration for mobility and scheduling Scheduling and transmission of control messages from the MME paging messages broadcast information PWS (Public Warning System) messages CSG (Closed Subscriber Group) handling Transport level packet marking in the uplink (ex. Setting the DSCP (DiffServ Code Point) 3GPP TS V E-UTRA and E-UTRAN; Overall description, June,

8 Interfaces X2 and S1 user plane aspect IP packet for a UE is encapsulated and tunneled using GTP-U (GPRS Tunneling Protocol User Plane) Local transport protocol is UDP No flow control, No error control X2 and S1 control plane aspect S1AP (S1 Application Protocol) is used to transport the signaling message between enode-b and the MME Local transport protocol is SCTP Guarantees delivery of signaling messages Support multiple SAE bearers S1-AP SCTP S1-AP SCTP IP IP L2 L2 L1 Access Layer HeNB S1-MME MME User plane for S1-U interface Control plane for S1-MME Interface SCTP : Stream Control Transmission Protocol 3GPP TS V E-UTRA and E-UTRAN; Overall description, June, EPS Bearer Service Architecture EPS bearer / E-RAB is established when the UE connects to a PDN Default bearer remains established throughout the lifetime of the PDN connection Dedicated bearer Any additional EPS bearer/e-rab that is established to the same PDN is referred to as a dedicated bearer. E-UTRAN EPC Internet UE enb S-GW P-GW Peer Entity End-to-end Service EPS Bearer External Bearer E-RAB S5/S8 Bearer Radio Bearer S1 Bearer Radio S1 S5/S8 Gi 3GPP TS V E-UTRA and E-UTRAN; Overall description, June,

9 QoS and EPS Bearers Multiple applications have different QoS requirements Different bearers are set up within EPS each being associated with a QoS GBR bearers Permanent allocation of dedicated transmission resources ex) VoIP Non-GBR bearers Do not guarantee any particular bit rate ex) web browsing, FTP transfer Each bearer has an associated QCI, and an ARP Priority and packet delay budget RLC mode, scheduling policy, queue management and rate shaping policy GBR : Minimum Guaranteed Bit Rate QCI: QoS Class Identifier ARP: Allocation and Retention Priority 17 Standardized QCI for LTE QCI (QoS Class Identifier) 1 Reso urce Type Prior ity Packet Delay Budget Packet Error Loss Rate 2 100ms 10-2 Conversational Voice Example Services ms 10-3 Conversational Video (Live Streaming) GBR ms 10-3 Real Time Gaming ms 10-6 Non-Conversational Video (Buffered Streaming) ms 10-6 IMS Signaling ms 10-6 TCP-based (e.g., www, , chat, ftp, p2p file sharing, Video (Buffered Streaming), progressive video, etc.) Non- 7 GBR 7 100ms 10-3 Voice, Video (Live Streaming)Interactive Gaming ms 10-6 TCP-based (e.g., www, , chat, ftp, p2p file sharing, Video (Buffered Streaming), progressive video, etc.) 3GPP TS v12.1.0, Policy and charging control architecture, Jun

10 User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control 19 Overview PDCP layer Process RRC messages in the control plane and IP messages in the user plane Header compression Security reordering and retransmission during handover RLC layer Segmentation and reassembly ARQ Reordering for HARQ MAC layer Multiplexing of data from different radio bearer Achieve QoS for each radio bearer Report the enodeb to the buffer size for uplink PDCP : Packet Data Convergence Protocol MAC: Medium Access Control QoS : Quality of Service RLC: Radio Link Control HARQ : Hybrid Automatic Repeat Request 20 10

11 PDCP overview Functions Header compression/ decompression of user plane data Security Ciphering and deciphering for user plane and control plane data Integrity protection and verification for control plane data Handover support In-sequence delivery and reordering of upper layer PDUs at handover Lossless handover for user plane data mapped on RLC Acknowledge Mode (AM) Discard for timeout user plane data * 3GPP TS v11.2.0: Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification (Release 11), April, Header Compression Robust Header Compression (ROHC) Introduced RFC3095 and RFC 4815 Increase channel efficiency by reducing overhead Robust at unreliable link Three different mode : Unidirectional mode(u-mode), Bidirectional Optimistic mode(o-mode), and Bidirectional Reliable mode(r-mode) Compression example VoIP (in the active period) payload 5,11~32 bytes (AMR@4.75~12.2kbps)+ header 40/60 bytes (RTP 12+UDP 8+IPv4 20/IPv6 40) payload 32 bytes + header 4~6 bytes Sender Payload RTP UDP IP Receiver IP RTP UDP Payload Compressor De-Compressor Framing/Error Detection RoHC Context Compressed Header Payload H RoHC Context Compressor De-Compressor Framing/Error Detection Wireless Link acticom mobile networks,

12 Header Compression Header Fields Classification Type Inferred Description They are never sent and they can be known by other component in the header IPv6 Ver* ToS< Flow ID** Length Hop Limit< Next Header* Source Address** Destination Address** Static* Send only once, their values never change during the stream UDP Source Port** Length Destination Port** Checksum< Ver^ P* E* CCnt< M< P.Type< Sequence Number< Staticdef** Staticknown^ Send only once, they give the definition of the stream They are never sent and their values are known RTP Timestamp< Source Synchronization Indentification(SSRC)** Source Contribution Identification (1 st )< Contributing source (CSRC)< Changing< Header fields with a changing value. The change can be periodic or randomly. They are always send Source Contribution Identification (last)< Application Data 23 Header Compression Header Fields Classification Type Inferred Static* Description They are never sent and they can be known by other component in the header Send only once, their values never change during the stream Staticdef** Staticknown^ Changing< Send only once, they give the definition of the stream They are never sent and their values are known Header fields with a changing value. The change can be periodic or randomly. They are always send 1 byte ROHC header 3~5 bytes Static Info Application Data 24 12

13 Header Compression ROHC compression with U,O,R operation mode 25 Security LTE security distribution NAS security Carried out for NAS messages / between UE and MME NAS messages are integrity protected and ciphered with extra NAS security header AS security (PDCP) Carried out for RRC and user plane data / between UE and enb RRC messages are integrity protected and ciphered U-plane data is only ciphered 3GLTEINFO,

14 Security Ciphering Prevent unauthorized user from seeing the content of communication For control plane (RRC) data and user plane data PDCP Control PDUs (ROHC feedback and PDCP status reports) are not ciphered Integrity protection Used to detect whether a text is tampered during delivery Control plane (RRC) data For RN, User plane data 32-bit Message Authentication Code for Integrity (MAC-I) 27 Discard of Data Packets To prevent excessive delay and queuing in the transmitter Discard Timer Related to buffer/delay management Defines maximum wait time Process When a PDCP SDU is received from upper layer, discard timer for the SDU is started When a discard timer expires, either the PDCP SDU is discarded or indication is sent to lower layer 28 14

15 PDCP PDU format PDCP Data PDU User plane PDCP Data PDU Long PDCP SN (12bits) (DRBs mapped on RLC AM or UM) Short PDCP SN (7bits) (DRBs mapped on RLC UM) Integrity protection for RN user plane (DRBs mapped on RLC AM or RLC UM) Extended PDCP SN (15 bits) (DRBs mapped on RLC AM) Control plane PDCP Data PDU For control plane SRBs PDCP Control PDU Interspersed ROHC feedback packet DRBs mapped on RLC AM or RLC UM Status report DRBs mapped on RLC AM Data (DRB) Data (SRB) ROHC feedback Status Report D/C SN or Type MAC-I O SN (7,12, 15 bits) Δ X SN (5 bits) O O Type X O Type X * 3GPP TS v11.2.0: Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification (Release 11), April, PDCP PDU format PDCP Data PDU <User plane PDCP Data PDU with short PDCP SN (7 bits)> <User plane PDCP Data PDU with long PDCP SN (12 bits)> <User plane PDCP Data PDU with extended PDCP SN (15 bits)> <RN user plane PDCP Data PDU with integrity protection> <Control plane PDCP Data PDU for SRBs> * 3GPP TS v11.2.0: Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification (Release 11), April,

16 PDCP PDU format PDCP Control PDU <PDCP Control PDU for interspersed ROHC feedback packet> <PDCP Control PDU for PDCP status report using a 12 bit SN> FMS: PDCP SN of the first missing PDCP SDU <PDCP Control PDU for PDCP status report using a 15 bit SN> * 3GPP TS v11.2.0: Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification (Release 11), April, User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control 32 16

17 RLC Overview Radio Link Control(RLC) Located between RRC/PDCP and MAC Error correction through ARQ Segmentation/Concatenation/Reassembly of RLC SDUs 3 transfer modes TM (Transfer Mode) Only used for RRC messages which do not need RLC configuration through BCCH, DL/UL CCCH and PCCH UM (Unacknowledged Mode) Utilized by delay-sensitive and error-tolerant real-time applications through DL/UL DTCH, MCCH or MTCH AM (Acknowledged Mode) Utilized by error-sensitive and delay-tolerant non-real-time applications through DL/UL DCCH or DL/UL DTCH SDU: Service Data Unit BCCH: Broadcast Control Channel CCCH: Common Control Channel PCCH: Paging Control Channel DTCH: Dedicated Traffic Channel MCCH: Multicast Control Channel MTCH: Multicast Traffic Channel DCCH: Dedicated Control Channel 33 TM RLC entity Features No segmentation/ No concatenation No RLC headers Deliver TMD PDUs Only for RRC messages which do not need RLC configuration SI messages Paging messages RRC messages which are sent when no SRBs other than SRB0 < Model of TM RLC entity > BCCH : Broadcast Control Channel PCCH : Paging Control Channel SRB: Signaling Radio Bearer CCCH : Common Control Channel SI: System Information TMD: Transparent Mode Data 34 17

18 UM RLC entity Features Segment or concatenate RLC SDUs Add or remove RLC headers Reorder received RLC PDUs Reassembly of RLC SDUs Used by delay-sensitive and error-tolerant real-time applications VoIP, MBMS concatenation < Model of UM RLC entity > DTCH : Dedicated Traffic Channel MCCH : Multicast Control Channel SDU: Service Data Unit MTCH : Multicast Traffic Channel MBMS: Multimedia Broadcast/Multicast Service UMD: Unacknowledged Mode Data 35 UM data transfer < Example of PDU loss detection with HARQ reordering > 36 18

19 AM RLC entity Features Similar function of UM RLC entity Support ARQ (Stop and Wait) Detect the loss of AMD PDU and request retransmission to peer Deliver AMD PDU, AMD PDU segment and STATUS PDU Used by error-sensitive and delay-tolerant non-real-time applications Interactive/background type services: Web-browsing, file downloading < Model of AM RLC entity > ARQ: Automatic Repeat request 37 AM data transfer Retransmission and resegmentation Status reports from receiving side ACK/NACK RLC data PDU is stored in retransmission buffer Resegment the original RLC PDU into smaller PDU segments < Example of RLC re-segmentation > 38 19

20 Data flow through L2 protocol stack A. Larmo et al., "The LTE link-layer design," Communications Magazine, IEEE, April User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control 40 20

21 MAC overview Functions Channel Mapping Building MAC PDU Random access Scheduling Power saving by Discontinuous Reception(DRX) Error correction through HARQ Multiplexing / Demultiplexing Transport Format Selection Priority handling Logical Channel prioritization Logical channel name Type Acronym Broadcast Control Channel Control BCCH Paging Control Channel Control PCCH Common Control Channel Control CCCH Dedicated Control Channel Control DCCH Multicast Control Channel Control MCCH Dedicated Traffic Channel Traffic DTCH Multicast Traffic Channel Traffic MTCH Transport channel name Direction Acronym Broadcast Channel Downlink BCH Downlink Shared Channel Downlink DL-SCH Paging Channel Downlink PCH Multicast Channel Downlink MCH Uplink Shared Channel Uplink UL-SCH Random Access Channel Uplink RACH 3GPP TS V11.5.0, "E-UTRA and E-UTRAN; Overall description; Stage 2(Release 11)", Mar, GPP TS V11.6.0, E-UTRA and E-UTRAN; Overall description, June, Channel Mapping in LTE 42 21

22 Downlink Channel Mapping(MAC-PHY) MAC PHY PxxCH : Physical xx Channel PDCCH(Physical Downlink Control Channel) PHICH(Physical HARQ Indicator Channel) 43 Uplink Channel Mapping(MAC-PHY) MAC PHY PUCCH(Physical Uplink Control Channel) 44 22

23 Logical Channels Control Channel Broadcast Control Channel (BCCH) Paging Control Channel (PCCH) Common Control Channel (CCCH) Multicast Control Channel (MCCH) Dedicated Control Channel (DCCH) Traffic Channels Description Broadcasting system control information Transfers paging information and system information change notifications Used for paging when the network does not know the location cell of the UE. Transmitting control information between UEs and network For UEs having no RRC connection with the network. A point-to-multipoint downlink channel Transmitting MBMS control information from the network to the UE, for one or several MTCHs Only used by UEs that receive or are interested to receive MBMS. A point-to-point bi-directional channel Transmits dedicated control information between a UE and the network Used by UEs having an RRC connection. Description Dedicated Traffic Channel (DTCH) Multicast Traffic Channel (MTCH) A point-to-point channel, dedicated to one UE Transfer of user information Exists in both uplink and downlink. A point-to-multipoint downlink channel for transmitting traffic data from the network to the UE Only used by UEs that receive MBMS 45 Transport Channels Downlink Channels Broadcast CHannel (BCH) Downlink Shared CHannel (DL-SCH) Paging CHannel (PCH) Multicast CHannel (MCH) Uplink Channels Uplink Shared Channel (UL-SCH) Random Access Channel (RACH) Description Transport the parts of the SI Transport downlink user data or control messages Transport remaining parts of the SI that are not transported via the BCH Transport paging information Inform UEs about updates of the SI and PWS messages Transport MBMS user data or control messages that require MBSFN combining Description Transport uplink user data or control messages Access to the network when the UE does not have accurate uplink timing synchronization or UE does not have any allocated uplink transmission resource 46 23

24 LTE Radio Frame Structure Type 1 : for FDD Radio frame(10ms) = 10 subframes(1ms) = 20 slots(0.5ms) 10 subframes for downlink, 10 subframes for uplink Uplink and downlink transmissions are separated in the frequency domain Data is split into TTI blocks of T=1ms (one subframe) 47 LTE Downlink Subframe Structure (for Type 1) 1 Slot Consists 7 symbols Resource Block 1 slot X 12 subcarriers =84 REs BPSK(1/2): 42bits 64QAM(3/4): 378bits Resource Element Amount of data in a symbol in a subcarrier BPSK(1/2): 0.5bits 64QAM(3/4): 4.5bits 48 24

25 LTE Radio Frame Structure Type 2 : for TDD radio frame(10ms) = 2 half-frames(5ms) = 8 subframes(1ms) + 2 special subframes (DwPTS, GP, UpPTS) Subframe 1 always consists special fields, although subframe 6 is by configuration One radio frame =10 ms One half frame =5 ms DwPTS : Downlink Pilot Time Slot GP : Guard Period UpPTS : Uplink Pilot Time Slot 1 ms # 0 # 2 # 3 # 4 # 5 # 7 # 8 # 9 Configu ration DwPTS Switch-poi nt periodi city GP UpPTS DwPTS GP UpPTS Uplink(U)/Downlink(D)/Special frame(s) Allocation Subframe number ms D S U U U D S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms D S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D D D D 6 5 ms D S U U U D S U U D 49 Building MAC PDU(MAC PDU Format) MAC PDU = MAC Header + MAC Payload MAC subheader Logical Channel ID (LCID), Length(L) field MAC control element Used for MAC-level peer-to-peer signaling Buffer status report / UE s available power headroom in uplink/ DRX command, etc. Headerless MAC PDU MAC PDU constructed without header Use it when MAC PDU is used to transport data from the PCCH or BCCH PCCH or BCCH : one-to-one corresponding between MAC SDU and MAC PDU 50 25

26 Random Access(RA) Procedure Purpose RA is performed when UE didn t assigned resource for data transmission Contention based Perform when enb doesn t know the presence of UE or UE have data to transmit while UE lost timing information Examples Initial access from RRC_IDLE RRC Connection Re-establishment procedure UL data arrival during RRC_CONNECTED requiring random access procedure» E.g. when UL synchronisation status is "non-synchronised" or there are no PUCCH resources for SR available Non-contention based Perform when enb know the incoming of UE or enb have data to transmit while UE lost timing information Examples Handover For positioning purpose during RRC_CONNECTED requiring RA DL data arrival during RRC_CONNECTED requiring random access procedure» E.g. when UL synchronisation status is non-synchronised 51 Random Access Procedure - Contention based(1) (0) Selection of preamble : select a preamble in preamble groups Preambles for contention based access (2 groups, select a group by message size) Preambles for contention-free access Total 64 preambles(spreading codes) in each cell (1) Preamble Transmission on RACH Set transmission power : according to DL estimation on RSRP Power ramping : increase transmission power by number of retrials (2) RA Response (PDCCH tagged with RA-RNTI + PDSCH) Send response for a UE if single preamble is detected This message includes UL resource grant, timing alignment information for sending third message Assign a temporary ID for UE(TC-RNTI) No RA Response for UE Backoff Back to Selection of preamble RSRP : Reference Signal Received Power TC-RNTI : Temporary Cell Radio Network Temporary Identifier RA-RNTI : Random Access Radio Network Temporary Identifier 52 26

27 Random Access Procedure - Contention based(2) (3) First PUSCH TX Includes TC/C-RNTI Conveys actual random access procedure message If multiple UEs selected same RACH and preamble in (1), collision occurs No collision enb detects one C-RNTI and get message from PUSCH (4) Contention Resolution on DL UE considers as success, and TC-RNTI is promoted to C-RNTI If (3) is collided No arrival of Contention Resolution for UE Backoff Back to Selection of preamble 53 Random Access Procedure - Non-Contention based (0) RA Preamble Assignment enb assigns to UE a non-contention Random Access Preamble before RA(ex> before handover) (1) RA Preamble Transmits non-contention RA Preamble (2) RA Response Conveys at least timing alignment information and initial UL grant for handover, timing alignment information for DL data arrival, RApreamble identifier 54 27

28 Data Transmission after RA - Downlink Scheduling(1) Dynamic Scheduling Signal and transmit data without periodicity Signaling is required at each transmission Signaling for dynamic scheduled data PDCCH(Physical Downlink Control Channel) DL-SCH(Downlink Shared Channel) 55 Data Transmission after RA - Downlink Scheduling(2) Semi-persistent scheduling Schedule periodical transmission Only the one signaling at first transmission is required Reduce signaling overhead Scheduling periodicity is configured by RRC Signaling for semi-persistent data (example : period = 4) No additional signalling for semipersistent scheduled data 56 28

29 Data Transmission after RA - Uplink Scheduling Procedure enodeb notifies the TX slot which can be used by UE for uplink transmission UE sends data through UL-SCH and activates HARQ process HARQ mechanism : Stop-and-Wait enodeb signals transmission result by HARQ ACK/NACK to UE For NACK, enodeb schedule for retransmission through PDCCH Example for N=4 : UE/eNB response after 4 subframe Subframe PDCCH(Physical Downlink Control Channel) UL-SCH(Uplink Shared Channel) PHICH(Physical HARQ Indicator Channel) 57 Wireless Packet Scheduling Algorithm Features of Scheduling Algorithms for Wireless Network Each user experience different transmission speed Channel environment differ by randomly through time Bursty error occurs User s channel capacity changes by fading Require to estimate channel environment Additional Slides 58 29

30 Signaling for Resource Allocation For resource allocation, enodeb requires Channel Quality Information(frequency specific) Traffic information(volume and priority, queue status Additional Slides Signaling tradeoff Data rate Overhead CQI measurement DL : through the feedback of CQIs by UEs UL : by Sounding Reference Signals(SRS) transmitted by UE to estimate ch. quality Frequency of the CQI reports is configurable Reduce overhead Accuracy Information about queue status DL : directly available at enb UL : specific reporting mechanism 59 Scheduling Algorithms Additional Slides Opportunistic algorithm / High Rate User First (HRUF) Simplest algorithm considering wireless channel Optimizing the total throughput Assign resources to user with best CQI Fairness problem occurs If the an user with best channel continuously generates traffic, then other users cannot be assigned wireless resource Other users cannot transmit their traffic Fairness and QoS are not assured max i ( t) () t i : Maximum transmission rate of user i 60 30

31 Scheduling Algorithms Fair algorithms Minimize UE latency Ex. Min-Max : Maximizes the minimum allocated rate Total Throughput reduced max min{ ( t )} i i Additional Slides 61 Scheduling Algorithms Proportional Fair Share Scheduling (PFSS) Algorithm Maximize Throughput with some degree of fairness Algorithm Basically, schedule UE when its instantaneous channel quality is high relative to its own average channel Reduce priority of UE by volume of received traffic increase fairness i () t i 2 k max ˆ i () t T e : Estimation interval 1 served rate in slot ( t -1) () t 1- ( t-1) Te Te Additional Slides () t log 1 SNR ( m, f) m : resource block f : subframe Large T e tends to maximize the total average throughput Small T e tends to maximize fairness 62 31

32 Retransmission HARQ Downlink : Asynchronous adaptive HARQ Asynchronous Retransmission with additional explicit signaling to indicate the HARQ process number to the receiver Adaptive HARQ Modulation and coding scheme(mcs), resource allocation can be changed Non-adaptive HARQ : retransmit with previous MCS and resource 63 Retransmission HARQ Uplink : Synchronous Non-adaptive/adaptive HARQ Uplink : Synchronous HARQ Synchronous Retransmission occur at predefined times relative to the initial transmission to reduce control signaling HARQ feedback seen by the UE ACK or NACK ACK or NACK PDCCH seen by the UE New Transmission Retransmission UE behaviour New transmission according to PDCCH Retransmission according to PDCCH(adaptive retransmission) ACK None No (re)transmission PDCCH is required to resume Retransmissions NACK None Non-adaptive retransmission PHICH PDCCH Grant ACK / NACK Grant UL-SCH Data New/ ReTx Data 64 32

33 Retransmission HARQ HARQ type HARQ combines FEC and ARQ Three types HARQ Type I HARQ Chase combining» Initial transmission and retransmission have same puncturing pattern 65 Retransmission HARQ HARQ type HARQ combines FEC and ARQ Three types HARQ Type II HARQ Incremental redundancy» The information bits does not retransmitted» The retransmitted packet has different puncturing pattern 66 33

34 Retransmission HARQ HARQ type HARQ combines FEC and ARQ Three types HARQ Type III HARQ Incremental redundancy» Initial transmission and retransmission have different puncturing pattern» Information bits will be retransmitted 67 Power Saving/Fast Wake-up Discontinuous Reception(DRX) Power saving in UMTS Through the state change from CELL_DCH to IDLE_MODE Fast recovering to CELL_DCH takes undesired delay DCH (Dedicated Channel) FACH (Forward access channel) PCH (Cell Paging channel) URA_PCH (URA Paging channel)

35 Power Saving/Fast Wake-up Discontinuous Reception(DRX) Power Saving in LTE/LTE-Advanced : Discontinuous Reception(DRX) Power saving with maintaining connected states When need power saving Change to DRX mode while maintain RRC_CONNECTED state UE can fast wake-up, because it maintain connectivity with enodeb RRC_CONNECTED DRX UE only listens at certain Intervals DRX reduced battery consumption DRX resume transfer even quicker DRX reduced signaling RRC_IDLE 69 Power Saving/Fast Wake-up Discontinuous Reception (DRX) UE does not monitor the downlink channels during such DRX period HARQ Round Trip Time (RTT) Short cycle, Long cycle Wake-up and check downlink during on duration only By two timer, control wake-up interval(=short DRX cycle and long DRX cycle) 1 4 enter short DRX mode 6 enter long DRX mode 3 2 Activate Inactivity timer 5 Activate Short DRX Cycle Timer 70 35

36 Control Plane Protocol 71 Control Plane Protocol Overview UE NAS enb S1-MME(logical interface) MME NAS RRC RRC S1-AP S1-AP PDCP PDCP SCTP SCTP RLC RLC IP IP MAC MAC MAC MAC PHY PHY PHY PHY LTE-Uu (radio interface) Non-access stratum PLMN selection Tracking area update Paging Authentication EPS bearer establishment, modification and release Access stratum control plane radio-specific functionalities The AS interacts with the NAS (upper layers) RRC: Radio Resource Control PDCP: Packet Data Convergence Protocol RLC: Radio Link Control PLMN: Public Land Mobile Network EPS: Evolved Packet System 72 36

37 Control Plane Protocol Overview : NAS Overview Highest stratum of c-plane (UE <-> MME) S1-MME (enb MME) Main functions EPS mobility management UE mobility EPS session management IP connectivity between the UE and a P-GW Security integrity protection and ciphering of NAS signaling messages. 3GPP TS V UMTS; LTE; NAS; EPS; Stage 3, July, GPP TS V8.9.0 LTE; GPRS enhancements for E-UTRAN access, March, Control Plane Protocol Overview : RRC Overview AS of c-plane (UE <-> enb) LTE-Uu interface Main functions Broadcast SI related to NAS and AS Paging Establishment of an RRC connection (UE<->E-UTRAN) Security functions (key management) Establishment of p-to-p Radio Bearers Mobility functions QoS management functions UE measurement reporting NAS direct message transfer (NAS<->UE) 3GPP, "TS V Radio Resource Control (RRC) Protocol specification (Release 10)," ed,

38 NAS/RRC State Protocol State Description NAS (UE,MME) RRC (UE,eNB) EMM-Deregistered UE is detached No EMM context has been established in UE and MME. EMM-Registered UE has been attached IP has been assigned An EMM Context has been established A default EPS Bearer has been activated The MME knows the location of the UE(TA). ECM-Idle No NAS signalling connection (ECM connection) No UE context held in E-UTRAN(eNB) The MME knows the location of the UE(TA) ECM-Connected NAS signalling connection (ECM connection; a RRC connection & a S1 signalling connection) The MME knows the location of the UE(cell) RRC-Idle RRC connection has not been established. RRC-Connected RRC connection has been established. TA: Tracking Area EMM: EPS Mobility Management ECM: EPS Connection Management MME: Mobility Management Entity 1. Netmanias, EMM and ECM States, NAS/RRC State When UE is switched on for the first time after subscription When UE is switched on after a long time after the power has been turned off There exists no UE context in the UE and MME

39 NAS/RRC State When UE is switched on within a certain period of time after the power has been turned off When ECM connection is released during communication due to radio link failure Some UE context can still be stored in the UE and MME (e.g., to avoid running an AKA procedure during every attach procedure). 77 NAS/RRC State When UE is attached to the network (MME) and using services The mobility of UE is handled by handover 78 39

40 NAS/RRC State 79 NAS/RRC State When UE is attached to the network (MME) and not using any service 80 40

41 NAS/RRC State 81 Control Plane Protocol Overview : RRC States RRC_IDLE UE known in EPC and has IP address UE location known on Tracking Area level Paging in TA controlled by EPC UE-based cell-selection and TA update RRC_CONNECTED UE known in EPC and E- UTRAN/eNB UE location known on cell level Unicast data transfer is possible enb-based mobility DRX supported for power saving HO 82 41

42 Control Plane Protocol Overview : UE Operation in RRC States RRC_IDLE Monitors a paging channel incoming calls system information change ETWS, CMAS measurement cell (re-)selection Acquire system information (MIB, SIBs) RRC_CONNECTED Monitors a Paging channel and/or SIB1 detect system information change Monitor control channels associated and data channel Provide channel quality and feedback information measurement and reporting Acquire system information DRX: Discontinuous Reception CMAS: Commercial Mobile Alert Service ETWS: Earthquake and Tsunami Warning System 83 Control Plane Protocol Overview : UE Camping Procedure NAS (1) PLMN selection Read USIM Read stored info on ME Select Band, PLMN, etc (10) Service Obtained (Camped) AS RRC (2) Trigger System Acquisition (4) Schedule Broadcast Control Channel read (6) Process SIB1 Check PLMN Is Cell reserved? Is CSG Id valid? Cell belong to Forbidden TA? Cell barred? If fail, go back to (3) If ok, go to (7) (8) All SIBs obtained PHY (3) Acquisition Scan Band/Freq (5) Read MIB/SIB1 Using SI-RNTI (7) SIB2 and Other SIBs (9) Cell is Selected and UE camps Bong Youl (Vrian) Cho, LTE RRC/RRM, TTA LTE/MIMO Standards/Technology Trainning, May

43 RRC Services Services provided to upper layers Broadcast of common control information Notification of UEs in RRC_IDLE receiving call, ETWS, CMAS Transfer of dedicated control information information for one specific UE Services expected from lower layers PDCP Integrity protection and ciphering RLC Reliable and in-sequence transfer of information without introducing duplicates with support for segmentation and concatenation ETWS: Earthquake and Tsunami Warning System CMAS: Commercial Mobile Alert Service 85 RRC Functions Broadcast of system information RRC connection control Inter-RAT mobility Measurement configuration control and reporting Transfer of information Others NAS common information For UEs in RRC_IDLE Cell (re-)selection parameters Neighboring cell information For UEs in RRC_CONNECTED Common channel configuration information Paging Establishment/modification/release of RRC connection or DRBs Initial security activation RRC connection mobility Radio configuration control (ARQ, HARQ, DRX) QoS control Recovery from radio link failure Security activation Transfer of RRC context information Establishment/modification/release of measurements Setup and release of measurement gaps Measurement reporting Dedicated NAS information Non-3GPP dedicated information UE radio access capability information Generic protocol error handling Support of self-configuration and self-optimization 86 43

44 Connection Control Security activation Ciphering of both control plane RRC data (SRBs 1 and 2) and user plane data (all DRBs) Integrity protection which is used for control plane data only Connection establishment, modification and release DRB establishment, modification and release SRB: Signaling Radio Bearers DRB: Date Radio Bearers 87 Connection Establishment and Release 88 44

45 DRB Establishment : Signaling Radio Bearers SRB: radio bearers that are used only for the transmission of RRC and NAS messages SRB0 For RRC messages Using the CCCH logical channel SRB1 For RRC messages (which may include a piggybacked NAS message) For NAS messages prior to establishment of SRB2 All using DCCH logical channel SRB2 For NAS messages Using DCCH logical channel Lower-priority than SRB1 Always configured by E-UTRAN after security activation CCCH: Common Control Channel DCCH: Dedicated Control Channel 89 DRB Establishment : Signaling Radio Bearers An EPS bearer is mapped (1-to-1) to a DRB A DRB is mapped (1-to-1) to a DTCH logical channel All logical channels are mapped (n-to-1) to the DL-SCH or UL-SCH DL-SCH or UL-SCH are mapped (1-to-1) to the corresponding PDSCH or PUSCH 90 45

46 Mobility Control Criteria for cell selection or reselection Radio link quality: primary criterion UE capability Subscriber type Cell type E-UTRAN provides a list of neighboring frequencies and cells; white-list or black-list 91 Mobility in RRC_IDLE : PLMN and Cell Selection PLMN selection The NAS handles PLMN selection based on a list of available PLMNs provided by the AS Cell selection (EMM-DEREGISTERED) The UE searching for the strongest cell on all supported carrier frequencies of each supported RAT Using NAS s support and stored information from a previous access Requirement: not take too long Cell reselection (EMM-REGISTERED) Move the UE to the best cell of the selected PLMN 92 46

47 Mobility in RRC_IDLE : Cell Reselection RRC_IDLE Mobility Measurement and evaluation of serving cell Measurement of neighbour cells Evaluation of neighbour cells for cell reselection Acquisition of the system information of the target cell Cell reselection to the target cell 93 Mobility in RRC_IDLE : Cell Selection Criteria Cell selection: received level & quality Srxlev & Squal Srxlev rxlevmeas rxlevmin rxlevminoffset Squal qualmeas qualmin qualminoffset rxlevmeas : Measured cell RX level value (RSRP) qualmeas : Measured cell quality value (RSRQ) rxlevmin : Minimum required RX level in the cell (dbm), in SIB1 qualmin : Minimum required quality level in the cell (db), in SIB1 rxlevminoffset, qualminoffset : offsets which may be configured to prevent ping-pong between PLMNs, in SIB

48 Mobility in RRC_CONNECTED 95 Mobility in RRC_CONNECTED : Handover UE Source enb Target enb Measurement Report Handover Preparation UE RRC context information (UE capabilities, current ASconfiguration, UE-specific RRM information Handover command RRCConnectionReconfiguration information for random access(mobility control, radio resource configuration), dedicated radio resource security configuration, C-RNTI Random access procedure RRCConnectionReconfigurationComplete 96 48

49 Mobility in RRC_CONNECTED : Handover Handover from Macro cell to macro cell HO triggering condition UE satisfies A3 condition during TTT -> HO request to S-eNB -> HO execution Hyst + offset TTT HO delay H/O completion A3 satisfaction HO execution 97 Mobility in RRC_CONNECTED : Seamless Handover Seamless handover OBJECTIVE : Interruption Time Minimization Used for all RBs carrying control plane data and user plane data mapped on RLC UM Loss tolerant and delay sensitive enb forwards only non-transmitted SDUs via X2 to target enb If transmission was started but has not been successfully received packets are lost Minimum complexity because context is not transferred between enb via X2 ROHC, COUNTS context is reset 3GPP TS , E-UTRA; PDCP specification

50 Mobility in RRC_CONNECTED : Seamless Handover Seamless handover in the downlink SDUs are transmitted to enb in sequence 손실된패킷은재전송되지않음 전송하지못한패킷은 X2 로전달 Reordering 은 UE 가수행 3GPP TS , E-UTRA; PDCP specification. 99 Mobility in RRC_CONNECTED : Lossless Handover Lossless handover OBJECTIVE : In-Sequence Delivery without Losses Possible because PDCP adds a sequence number to packets Applied for radio bearers that are mapped on RLC-AM Delay-tolerant and loss-sensitive Un-acknowledged packets are forwarded via X2 an retransmitted they may be received twice ROHC context is reset 3GPP TS , E-UTRA; PDCP specification

51 Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the uplink SDUs are delivered to the GW in sequence Serving enb transfers via X2, out-of-sequence SDUs STATUS TRANSFER contains Sequence and Hyper Frame Numbers Unacknowledged SDUs are retransmitted duplicity of P4 3GPP TS , E-UTRA; PDCP specification. 101 Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the downlink SGW transmits End Marker to serving enb Target enb knows when it can start to transmit SDUs from SGW SDUs are delivered to the UE in sequence 3GPP TS , E-UTRA; PDCP specification

52 Mobility in RRC_CONNECTED : Detailed Handover Procedure (1/3) S1-Based handover Admission Control 103 Mobility in RRC_CONNECTED : Detailed Handover Procedure (2/3)

53 Mobility in RRC_CONNECTED : Detailed Handover Procedure (3/3) UE Source enb Target enb MME Serving GW Step 1: HO Preparation Step 2: HO Execution <S1AP>Handover Notify <GTP-U>End Marker <GTP-C>Modify Bearer Request Switch DL Path Deliver bufferd and in transit packets to target enb Downlink data Uplink data <GTP-U> End Marker <GTP-C>Modify Bearer Response Downlink data Uplink data Step 3: HO Completion Packet data Resource Release Packet data <S1AP>UE Context Release Command <S1AP>UE Context Release Complete <GTP-C>Delete Indirect Data Forwarding Tunnel Request <GTP-C>Delete Indirect Data Forwarding Tunnel Response 105 Measurements Measurement Configuration: RRCConnectionReconfiguration message Measurement objects: carrier frequency or list of cells Reporting configurations: RSRP/RSRQ, number of cells Measurement identities Quantity configurations: filtering Measurement gaps: time periods UE may measure and report Serving cell Listed cells Detected cells on a listed frequency RSRP: Reference Signal Received Power RSRQ: Reference Signal Received Quality

54 Measurements : Measurement report triggering Event A1 A2 A3 A4 A5 A6 (Rel-10) B1 B2 Condition Serving becomes better than threshold: Serving becomes worse than threshold: Neighbor becomes offset better than Pcell: Neighbor becomes better than threshold: PCell becomes worse than threshold1 and neighbor becomes better than threshold2: 1 & 2 Neighbour becomes offset better than SCell: Inter RAT neighbor becomes better than threshold: PCell becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2: 1 & 2 Mserving/Mn/Mp/Ms: measurement result of serving cell/neighbor cell/pcell/scell Of/Oc: frequency/cell specific offset PCell: Primary (serving) Cell SCell: Secondary (serving) Cell <- carrier aggregation 3GPP, "TS V Radio Resource Control (RRC) Protocol specification (Release 10)," ed, Measurements : Reference Signal Received Power RSRP UEs measure RSRP over the cell-specific RSs Periodic measurement Intra-freq.: 200ms Inter-freq.: 480ms (proportion to the DRX cycle) Requirements intra-frequency: 8 cells inter-frequency: 4 cells * 3 carriers = 12 cells

55 Measurements : Reference Signal Received Quality Reference Signal Received Quality (RSRQ) RSRQ RSSI the total received power interference from all sources serving and nonserving cells adjacent channel interference and thermal noise LTE Rel-8 RSRQ was applicable only in RRC_CONNECTED state Handover LTE Rel-9 RSRQ was also introduced for RRC_IDLE Cell reselection RSSI : Received Signal Strength Indicator 109 Measurements : System Information Blocks SIB Contents MIB parameters which are essential for a UE s initial access to the network SIB1 parameters needed to determine if a cell is suitable for cell selection information about the time-domain scheduling of the other SIBs SIB2 common and shared channel information SIB3-8 parameters used to control intra-frequency, inter-frequency and inter- RAT cell reselection SIB9 signal the name of a Home enodeb (HeNBs) SIB10-12 ETWS notifications and CMAS warning messages SIB13 MBMS related control information ETWS: Earthquake and Tsunami Warning Service MBMS: Multimedia Broadcast/Multicast Services CMAS: Commercial Mobile Alert System

56 Measurements : RRC messages to transfer SI (example) MIB(SIB1) message is carried by PBCH(PDSCH) created every 40(80) msec broadcasted every 10(20) msec Other SI messages are created and broadcasted dynamically on the PDSCH Message Content Period Applicability MIB Most essential parameter 40 ms Idle/connected SIB1 Cell access related parameters, scheduling information 80 ms Idle/connected 1 st SI SIB2: Common and shared channel configuration 160 ms Idle/connected 2 nd SI SIB3: Common cell reselection information and intra-frequency cell reselection parameters other than the neighbouring cell information SIB4: Intra-frequency neighbouring cell Information 320 ms Idle only 3 rd SI SIB5: Inter-frequency cell reselection information 640 ms Idle only 4 th SI SIB6: UTRA cell reselection information 640 ms Idle only SIB7: GERAN cell reselection information PBCH: Physical Broadcast Channel SFN: System Frame Number PDSCH: Physical Downlink Shared Channel 111 Paging Paging transmit paging information to a UE in RRC-IDLE -> RRC-CONNECTED MME initiates paging Phone call DL traffic SI change ETWS notification UE Monitor PDCCH at certain UE-specific subframes <RRC>Paging P-RNTI check enb Random access procedure <NAS>Service Request <S1AP>Paging MME Send to all enbs in a TA <S1-AP>Initial UE MESSAGE [NAS: Service Request] [enb UE signalling connection ID] <S1-AP>Initial Context Setup Request <RRC>Radio Bearer Setup [NAS message] [MME UE signaling connection ID] [Security Context] [UE Capability Information] <RRC>Radio Bearer Setup Complete [Bearer Setup:serving S-GW TEID, QoS Profile] <S1-AP>Initial Context Setup Complete [enb UE signalling connection ID] [Bearer Setup Confirm:eNB TEID] TA: Tracking Area PDCCH: Physical Downlink Control Channel RNTI: Radio Network Temporary Identifier P-RNTI: Paging RNTI ETWS: Earthquake and Tsunami Warning service

57 Paging : Tracking Area TAI: Global Unique ID PLMN ID + TAC In order to paging, MME needs TAI Ex) MME1 sends paging to UE1 => broadcast all the enbs in TAI1 & TAI2 TAI list UE receives TAI list when it is connected TAU When UE move out from own TAI list Periodic TAU TAI: Tracking Area Identifier TAC: Tracking Area Code TAU: Tracking Area Update 113 Radio Resource Management : RRM Functions Power control Scheduling Cell search Cell reselection Handover Radio link or connection monitoring Connection establishment and re-establishment Interference management Location services Self-Optimizing network (SON) Network planning

58 Radio Resource Management : LTE RRM Characteristic Characteristics Details Interference fluctuation Fast time and frequency domain scheduling Wide range of DRX DRX: 0~2.5 sec Different RATs Various cell sizes Various frame structure LTE, 3GPP & non-3gpp legacy RATs Different channel structure Macro / femto / pico A few m ~ tens of km FDD(synchronized or unsynchronized), TDD Low latency requirements Measurements & reports HO MBMS: Multimedia Broadcast/Multicast Service 115 Power Control LTE power control is not as critical as in WCDMA LTE uplink resources are orthogonal -> no intra-cell interference (theory) frequency selective scheduling Power Control Maximize system capacity Minimize inter-cell interference SRSs: Sounding Reference Signals RB: Resource Block RE: Resource Element

59 Power Control : UL Power Control Uplink power control: PUSCH, PUCCH and the SRSs (unit of RB) Semi-static basic open-loop operating point : cell specific power level : factor to trade off the fairness of uplink scheduling against total cell capacity PUCCH: always 1-> maximize fairness for cell edge UE : downlink pathloss estimate calculated in the UE dynamic offset updated from subframe to subframe : MCS dependent power offset : TPC command related power TPC command: relative power offset comparing to its previous Tx power, or absolute power SRSs: Sounding Reference Signals RB: Resource Block RE: Resource Element TPC: Transmitter Power Control 3GPP, "TS v LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 10)," July Power Control : DL Power Allocation Downlink power allocation (unit of RE) Cell specific RS EPRE (Energy per RE) : semi-static (enb signals UE) or PDSCH RE s position (index 0, 4) 10log : 0dB for all transmission modes except multi-user MIMO : UE specific parameter from higher layer : 2 (transmit diversity with 4 antenna ports) or 1 (otherwise) : cell specific parameter from higher layer Cell-specific RS power, signaled in SIB2 PDCCH power depending on / PDSCH power to RS, where NO RSs are present, is UE specific and signaled by higher layer as RE: Resource Element 3GPP, "TS v LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 10)," July Subcarrier Index EPRE For PDSCH power in same symbol as RS an additional cell specific offset is applied, that is signaled by higher layer

60 Cell Search Cell Search UE acquires the carrier frequency, timing and cell identity of cells Cell search within E-UTRAN Identify one of the 504 unique Physical Cell Identities (PCIs) Requirements Maximum permissible cell identification delay( DRX cycle) Minimum synchronization signal quality : the energy per Resource Element (RE) of the synchronization signal : total received energy of noise and interference on the same RE Case Max. Delay Min. / Intra-frequency DRX (0~40ms) Inter-frequency DRX(0~160ms) 800ms -6dB 3.84s -4dB 119 Radio Link Failure Handling 1 st phase Layer 1 monitors downlink quality and indicates problems to RRC RRC filters L1 indications and starts a timer if no recovery within 1 st phase, triggers 2 nd phase Layer 2 monitors random access attempts and indicates problems to RRC RRC triggers 2 nd phase 2 nd phase Radio Link Failure (RLF): Possible recovery through an RRC Connection Reestablishment procedure reestablishment may be performed in any cell to which the UE s context is made available If no recovery within 2nd phase, UE goes autonomously to IDLE

61 Inter-Cell Interference LTE is designed for frequency reuse 1 (To maximize spectrum efficiency) All the neighbor cells are using same frequency channels no cell-planning to deal with the interference issues Shared channels RB scheduled to cell edge user can be in high interference ->low throughput / call drops Control channels Neighbor interference -> radio link failures at cell edge. 121 Inter-Cell Interference Coordination ICIC mitigates interference on traffic channels only Power and frequency domain to mitigate cell-edge interference from neighbor cells X2 interface is used to share the information between the enbs A.Neighbor enbs use different sets of RBs improves cell-edge SINR decrease in total throughput B.Center users: complete range of RBs Cell-edge users: different sets of RBs C.Scheme B + different power schemes For center/cell edge user: low/high power

62 Summary of Control Plane : Initial Attach Procedure Summary of Initial Attach Procedure S-GW: Serving Gateway P-GW: Packet Data Network Gateway HSS: Home Subscriber Server PCRF: Policy and Charging Rule Function SPR: Subscriber Profile Repository IMSI: International Mobile Subscriber Identity Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2편), September, Summary of Control Plane : Acquisition of IMSI Summary of Initial Attach Procedure Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

63 Summary of Control Plane : Acquisition of IMSI GUMMEI: Globally Unique MME ID ECGI: E-UTRAN Cell Global Identifier TAI:Tracking Area Identity Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September, Summary of Control Plane : Authentication Summary of Initial Attach Procedure Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

64 Summary of Control Plane : Authentication MCC: Mobile Country Code MNC: Mobile Network Code PLMN: Public Land Mobile Network ID PLMN=MCC+MNC Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2편), September, Summary of Control Plane : NAS Security Setup Summary of Initial Attach Procedure Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

65 Summary of Control Plane : NAS Security Setup Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September, Summary of Control Plane : Location Update Summary of Initial Attach Procedure Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

66 Summary of Control Plane : Location Update APN: Access Point Name QCI: QoS Class identifier ARP: Allocation and Retention Priority AMBR: Aggregated Maximum Bit Rate Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September, Summary of Control Plane : EPS Session Establishment Summary of Initial Attach Procedure Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

67 Summary of Control Plane : EPS Session Establishment (1) TEID: Tunnel Endpoint ID Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September, Summary of Control Plane : EPS Session Establishment (2) TEID: Tunnel Endpoint ID Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September,

68 Summary of Control Plane : EPS Session Establishment (3) Netmanias, EMM Procedure: 1. Initial Attach for Unknown UE (2 편 ), September, Summary of Control Plane : EPS Session Establishment (4)

69 Summary of Control Plane 137 LTE-Advanced Features Heterogeneous Networks Carrier Aggregation CoMP

70 Heterogeneous Networks Objective Coverage extension Interference mitigation Capacity increase Nodes Macro cells (enbs) RRH (Remote Radio Head) Small cells Antenna extension with wired backhaul (Fiber) Tx power: 46 dbm Relay Perform a role of enb in a UE perspective Wireless backhaul Tx power: 30 dbm Pico cells (Pico enbs) Similar to macro enbs but with lower power Wired backhaul (X2 interface) Tx power: dbm Femto cells (HeNBs) CSG/OSG/Hybrid Indoor deployment by the customer usually without planning HeNB gateway can (optionally) be deployed to manage a large number of HeNBs (Rel-9/10) High speed internet access for backhaul Tx power: <23 dbm CSG: Cell Subscriber Group OSG: Open Subscriber Group D Lopez-Perez, A Valcarce, G De La Roche, J Zhang, Enhanced intercell interference coordination challenges in heterogeneous networks. IEEE Wirel Commun. 18(3), 22 30, Heterogeneous Networks Core Network Internet Wireless High speed Internet X2 interface Femto Pico Fiber Macro Relay RRH Khandekar, A.; Bhushan, N.; Ji Tingfang; Vanghi, V., "LTE-Advanced: Heterogeneous networks," Wireless Conference (EW), 2010 European, vol., no., pp.978,982, April

71 Heterogeneous Networks :Hot issues for Small cell Networks Dual connectivity UE maintain connections with macro cell and small cell Macro cell manages the C-plane of UE connections Small cell manages only U-plane protocols of UE connections Mobility enhancement Lite handover algorithm to reduce handover overhead between macro cell and small cell User-centric cooperative handover scheme Interference handling Interference between macro cell and small cell, small cell and small cell Transmission power control of small cell according to amount of traffic Bandwidth sectoring for small cells 윤영우, 3GPP LTE Rel-12 & Onwards 주요요소기술및표준동향, 전자공학회지, 제 40 권 4 호, pp , 2013 년 4 월. 141 Heterogeneous Networks :Hot issues for Small cell Networks Cell discovery Efficient cell searching considering small cell interferences and plenty of cells Effective cell discovery considering unplanned small cells Improved spectral efficiency High modulation scheme (e.g. 256QAM) with high received power in small cells Reducing reference signal overhead 윤영우, 3GPP LTE Rel-12 & Onwards 주요요소기술및표준동향, 전자공학회지, 제 40 권 4 호, pp , 2013 년 4 월

72 Heterogeneous Networks :Current works Cloud-RAN* ( 삼성전자 ) Separate Digital Unit and Radio Unit in enb CCC (Cloud control center) control multiple RRH Support CA, CoMP, ICIC(Inter-cell interference) Inter-eNB CA is an alternative to fiber based cloud-ran <CCC architecture> <Inter-eNB CA architecture> 143 *3GPP, RWS , Samsung Electronics, Technologies for Rel-12 and Onwards, June Heterogeneous Networks :Current works Phantom cell* (NTT Docomo) Macro cell manages control signals for small cells Small cell manage only data transmission High bandwidth efficiency <Phantom cell architecture> *3GPP, RWS , NTT DOCOMO, Requirements, Candidate Solutions & Technology Roadmap for LTE Rel-12 Onward, June

73 Heterogeneous Networks :Current works Soft Cell* (Ericsson & ST-Ericsson) Dual connectivity anchor and booster carriers Logical connection on anchor and booster carrier Does not necessarily imply simultaneous UE physical-layer Rx/Tx of booster and anchor carrier(s) Anchor carrier Macro node connection System information, basic RRC Low-rate/high-reliability user data Based on Rel-8 Rel-11 structures Booster carrier Pico node connection (when beneficial) Offloading of large data volumes Ultra-lean transmissions, minimum amount of overhead * 3GPP, RWS , Ericsson & ST-Ericsson, Views on Rel-12, June Heterogeneous Networks :Current works Hyper-dense LTE network* (Qualcomm) Capacity is increased with a dense deployment of self-backhauled small cells ( 3 rd layer of small cell ) * 3GPP, RWS , Qualcomm, 3GPP RAN Rel-12 & Beyond, June

74 Heterogeneous Networks : Current works Handover between macro cell and femto cell HeNB compared to enb Small coverage Low tx power Random deployment by users Indoor deployment enb enb Symmetric signal power Lower interference Same tx power of neighbor enbs enb HeNB Asymmetric signal power Higher interference from enb to HeNB Large PL due to wall-loss Higher interference -> worse HeNB RSRQ Require different event for HO decision Relative value Absolute value 147 Heterogeneous Networks : Current works Femto cell Handover Inbound handover Femto-to-femto handover Outbound handover

75 Femto cell Inbound HO ( 아주대 ) Femto cell inbound handover: Macro -> Femto cell HO triggering condition Signal power level: macro enb >> femto HeNB UE satisfies A4 condition during TTT -> HO request to S-eNB -> HO execution TTT HO delay Measured value threshold Satisfaction A4 event hyst HO execution H/O completion 149 Femto cell Inbound HO : SI Measurement ( 아주대 ) System Information Essential parameters by which the network can control the cell selection process In the macro HO procedure, the UE gets the SI of target cell from serving enb But, in the inbound HO from macro cell to CSG cell S-GW don t manage the cell information of femto cells UE have to measure SI of target cells C.-H. Lee and J.-H. Kim, System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE Networks, IEEE Communications Letters, vol. 17, no. 1, pp , Jan

76 Femto cell Inbound HO : SI Measurement ( 아주대 ) Serial methods UE measures MIB & SIB1 packets cell-by-cell Scheduled/Autonomous Parallel method UE measures all MIB packets UE measures SIB1 packets in order of the expected arrival time. Autonomous C.-H. Lee and J.-H. Kim, System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE Networks, IEEE Communications Letters, vol. 17, no. 1, pp , Jan Femto cell Inbound HO : SI Measurement ( 아주대 ) Simulation environment OPNET Assumption UE find 6 femtocells during every neighbor search Simulation parameters C.-H. Lee and J.-H. Kim, System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE Networks, IEEE Communications Letters, vol. 17, no. 1, pp , Jan

77 Femto cell Inbound HO : SI Measurement ( 아주대 ) Measurement Delay Scheduled > Autonomous methods Serial > Parallel methods However, autonomous methods have possibility of packet drop, because the serving cell cannot know whether the UE is disconnected or not 153 Heterogeneous Network : Market Status Number of companies * Informa Telecoms & Media, Small cell Market Status,

78 Heterogeneous Network : Market Status Selection of pricing models for femtocell services Market Consumer Enterprise Pricing model Add-ons for unlimited calling Free Low upfront fee Monthly fee High upfront fee Deployment examples MOLD TELECOM, Sprint, YES OPTUS Softbank, Vodafone(Greece), SFR Vodafone(UK, Italy, Hungary), Verizon Sprint, Movistar, NTT DoCoMo All operators * Informa Telecoms & Media, Small cell Market Status, Femtocell deployment segmentation according to target group Target Group Number of deployme nts Consumer 26 Enterprise 6 Consumer & Enterprise 8 Public 5 Rural 1 Examples Vodafone UK, AT&T, Cosmote T-Mobile UK, Network Norway, Orange France Vodafone NZ, Verizon Wireless, Sprint Vodafone Qatar, SK Telecom, TOT Thailand Softbank (using satellite backhaul) 155 Heterogeneous Network : Market Status Company Country Offering Example Pricing Capabilities Sprint Verizon Vodafone at&t SFR NTT Docomo US US UK US France Japan Consumer and Enterprise: Airave Consumer and Enterprise: Network Extender Consumer: Sure Signal(UMTS/HSPA) US$4.99 per month (US$10 for unlimited calling, US$20 for family plans) Launch date Up to 6 users US$ Up to 3 users Various options 50 upfrontfree for > 45 contracts Consumer: 3G MicroCell US$159 Up to 4 3G users Consumer: Home 3G(UMTS/HSPA) Consumer: My Area(UMTS/HSPA) 199 upfront Up to 4 3G users US$10 per month Up to 4 users Up to 4 3G users * Informa Telecoms & Media, Small cell Market Status,

79 Heterogeneous Network : Market Status Company Country Offering Example Pricing Capabilities Softbank KDDI SKtelecom Vodafone Orange Japan Japan South Korea Italy France Consumer: Femtocell service(wcdma) Consumer: au Femtocell (CDMA2000 1xEV-DO) Public: Femtocells for data offload Consumer and Enteprise: Booster PrivatiBooster Enterprise: Couverture Site Confort Free of charge Free of charge (in coverage deadspots) Deployed in public areas Consumer: 240Enterprise: 780 Upfront fee: 1,400Monthly fee: 70Multi-FAP plans available Up to 4 3G users Up to 4 3G users Up to 4 3G users Consumer/Ent erprise: Up to 4/8 users Launch date Up to 4 users * Informa Telecoms & Media, Small cell Market Status, Heterogeneous Network : Commercial Products in Korea Service providers deploy small cells SKT : 3G femto cell : 3G femto cell + WiFi AP : LTE femto cell + WiFi AP Power over Ethernet : Femto Remote Solution Reduce Femto cell interference KT 3G femto cell VDSL No HO supported : LTE femto cell 100Mbps optical fiber : Home Femto cell LGU : LTE femto cell Use different carrier frequency with macro cell

80 LTE-Advanced Features Heterogeneous Networks Carrier Aggregation Offloading 159 Carrier Aggregation Overview What is the Carrier Aggregation (CA)? Two or more component carriers (CCs) are aggregated UE may simultaneously receive or transmit one ore multiple CCs corresponding to multiple serving cells Motivation BW aggregation is required for IMT-Advanced Peak data rate: 1 Gbps in the downlink, 500 Mbps in the uplink BW requirement set by ITU-R: up to 100 MHz

81 Carrier Aggregation Modes Contiguous carrier aggregation Possibly only one FFT module and one radio frontend Similar propagation characteristics Non-contiguous carrier aggregation Aggregation of fragmented spectrum Intra- or single-band Inter- or multi-band Carrier Aggregation Band A CC1 CC2 CC3 <Contiguous Carrier Aggregation> Carrier Aggregation Band A CC1 CC2 <Non-contiguous Carrier Aggregation (Intra)> f Carrier Aggregation f FFT: Fast Fourier transform Band A CC1 Band B CC2 <Non-contiguous Carrier Aggregation (Inter)> f 161 Carrier Aggregation in LTE Carrier aggregation in previous 3GPP 3GPP2 1xEV-DO Rev. B (multiple 1.25 MHz carriers) 3GPP HSPA (up to 4 DL / 2UL carriers, of 5 MHz each) Contiguous, same band, same BW Carrier aggregation in LTE Contiguous and non-contiguous Various carrier BW (1.4, 3, 5, 10, 15, 20 MHz) Various frequency band (SKT: 800MHz, 1.8GHz, KT: 900MHz, 1.8MHz, LG U+: 800MHz, 2.1GHz) Control channel design for UL/DL Backward compatibility Reuse of Rel. 8/9 RF designs and implementation at the enb and UE

82 Serving Cells in CA Primary serving cell (PCell) The RRC connection is handled by the PCell, Secondary serving cell (SCell) SCell information is obtained via dedicated signaling on PCell SCells provide additional radio resources Primary Serving Cell(PSC), Primary Component Carrier (PCC), RRC connection and data Secondary Serving Cell(SSC), Secondary Component Carrier (SCC), User data only J.Wannstrom, Carrier Aggregation explained, May, Protocol Architecture for CA (1/3) Rel. 10 UE can be configured with multiple serving cells When in RRC_CONNECTED state Each serving cell corresponds to a different DL CC Radio Bearers ROHC... ROHC ROHC... ROHC PDCP... Security... Security Security... Security RLC Segm. ARQ etc... Segm. ARQ etc... Segm. ARQ etc... Segm. ARQ etc Segm. Segm. CCCH BCCH PCCH Logical Channels MCCH MTCH Unicast Scheduling / Priority Handling MBMS Scheduling MAC Multiplexing UE1... Multiplexing UEn Multiplexing HARQ... HARQ HARQ... HARQ Transport Channels DL-SCH on CC1 DL-SCH on CCx DL-SCH on CC1 DL-SCH on CCy BCH PCH MCH * 3GPP TS V E-UTRA and E-UTRAN; Overall description, June,

83 Protocol Architecture for CA (2/3) Control plane UE only has one RRC connection with the network UE (re-)establishes RRC connection on a single cell RRC signaling is used to add, remove, or reconfigure additional serving cells UE is assigned a single C-RNTI (Cell Radio Network Temporary Identifier) Uniquely identify the RRC connection of the UE For scheduling purposes on the PDCCH transmitted on any of the activated DL CCs MAC is used for dynamic management of serving cells to be used among the configured set of serving cells 165 Protocol Architecture for CA (3/3) Data plane CA is only exposed to the MAC sublayer MAC performs unicast scheduling and priority handling across all active serving cells of a UE in a way that is transparent to upper layers Each transport block and its potential HARQ retransmission are mapped to a single serving cell Independent HARQ process for each DL or UL CC

84 CA scheduling Normal scheduling Scheduling grant and resource on same carrier Cross-carrier scheduling Scheduling grant and resource NOT on the same carrier Schedule resources on SCC without PDCCH The CIF (Carrier Indicator Field) on PDCCH (represented by the red area) indicates on which carrier the scheduled resource is located. PCC SCC PCC SCC PCC SCC PCC SCC 167 Status of Commercial Services for CA (1/6) Bandwidth allocation for KT, SKT, LGU Uplink Downlink

85 Status of Commercial Services for CA (2/6) Hot Issues about Bandwidth allocation Primary Primary Secondary SKT -LTE -20Mhz 800MHz~ LGU -LTE -20Mhz 경매 -LTE -35Mhz 1.8GHz~ 경매 -LTE -15Mhz KT -LTE -20Mhz SKT -LTE -20Mhz LGU -CDMA -20Mhz Frequency Secondary LGU -LTE -20Mhz SKT -WCDMA -60Mhz KT -WCDMA -40Mhz 2.1GHz~ Frequency 경매 -LTE -40Mhz 경매 -LTE -40Mhz 2.6GHz~ Frequency 169 Status of Commercial Services for CA (3/6) Commercial services for Multi-carrier(MC) and CA * Multi-carrier technology Select one of frequency bands to optimize the load balancing when LTE data traffic increases SKT LTE-A network deployment for 850Mhz & 1.8GHz frequency band Deployment completion in 84 major cities, Korea ( ) Starting MC service ( ) Starting CA service ( ) LG U+ LTE-A network deployment for 800Mhz & 2.1GHz frequency bands Deployment completion in Seoul and major cities, Korea (3Q of 2013) Deployment completion in rest cities, Korea (4Q of 2013) Starting MC service ( ) Starting CA service ( ) SKT hompage, SK 텔레콤, 30 일 84 개시중심가로 LTE-A 확대, July, LGU+ homepage, LG 유플러스, 세계최초 100% LTE 상용화, July,

86 Status of Commercial Services for CA (4/6) SKT: 아무나가질수없는속도 LTE-A 세계최초 Carrier Aggregation 상용화서비스 한시적 (7 월 ) 데이터 2 배제공 171 Status of Commercial Services for CA (5/6) LGU+: 100% LTE 가아니면요금을안받겠습니다. 세계최초 100%LTE 상용화 (Voice 와 data 를동시서비스 ) WCDMA(3G) 망없음

87 Status of Commercial Services for CA (6/6) KT: 난데이터가 2 배라구요! Multi carrier/carrier Aggregation 서비스안함 한시적으로데이터량 2 배제공 ( ~10 월 ) 173 LTE-Advanced Features Heterogeneous Networks Carrier Aggregation CoMP

88 CoMP CoMP (Coordinated MultiPoint transmission and reception) The coordination of transmissions from multiple cells (especially at the cell edge Basic CoMP schemes can be realized in Release 8 between the cells controlled by a given enodeb The evolution of LTE-Advanced for Release 11 or beyond * 윤영우, LTE-Advanced 표준기술 (REL-10 동향및 REL-11 전망 ), 한국통신학회지 ( 정보와통신 ), * S.Seia, I. Toufik, M. Baker, LTE The UMTS Long Term Evolution From Theory to Practice, Second Edition. 175 CoMP CoMP schemes Coordinated scheduling / beamforming Share the channel and scheduling information between the coordin ated cells to reduce interference in a UE Scheduling UE / beamforming Coherent joint transmission Multipoint transmission to single UE Dynamic switching (Fast cell selection) Dynamically handover to the selected cell * S.Seia, I. Toufik, M. Baker, LTE The UMTS Long Term Evolution From Theory to Practice, Second Edition. * NTT DOCOMO, R : Investigation on Coordinated Multipoint Transmission Schemes in LTE-Advanced Downlink, 3GPP TSG RAN WG1, meeting 55bis, Ljubljana, Slovenia, January

89 CoMP CoMP schemes <Coordinated scheduling> <Coordinated beamforming> Coherent Fast cell selection (FCS) <Coherent joint transmission> < Dynamic switching> * S.Seia, I. Toufik, M. Baker, LTE The UMTS Long Term Evolution From Theory to Practice, Second Edition. * NTT DOCOMO, R : Investigation on Coordinated Multipoint Transmission Schemes in LTE-Advanced Downlink, 3GPP TSG RAN WG1, meeting 55bis, Ljubljana, Slovenia, January CoMP Related Example : BS Cooperation BS cooperation 성능분석 BS cooperation 네트워크관점의성능평가 시뮬레이터구현사항 기지국구성기지국당단말수 10개단말기지국반경 1 Km Pathloss model Shadowing Model 채널모델 Thermal Noise Den sity 신호결합및측정 Soft combining, 1 서빙기지국, 2 협력기지국, 16 dummy 기지국 log10(R) (R in km) Log-normal dist (mean: 0, variation: 8 db) -174dBm/Hz Bandwidth 10Mhz (1024 FFT) Frame 5 msec (TDD) MCS level QPSK ½, 16QAM ½, 64QAM½ Cell load 90% Triggering 셀내위치기반동작 / SINR 신호기반동작 자원할당방법 협력기지국간동일 Band 할당 *J. S. Kim, K. C. Go, S. K. Oh and J. H. Kim, "Performance Evaluation of BS Cooperative Communication in Networks-Wise," in Proc. ICUIMC 2013, Kota Kinabalu, Malaysia, Jan Jan. 19,

90 CoMP Related Example : BS Cooperation Messages for BS cooperation BS cooperation 동작을위한 MAC 메시지플로우설계 IEEE e system 기반 유 / 무선 Control message 설계 Message overhead ( 무선 ) Cooperative Service Request (208 bits) Cooperative Service request info CQI info Location info Cooperative Service Response (381 bits) Cooperative service response info Resource allocation info Synch info 179 CoMP Related Example : BS Cooperation 셀경계사용자비율에따른성능 * <Average cell-edge throughput> <Total network throughput> BS cooperation 사용에따른셀경계사용자의 Throughput 향상 BS cooperation 사용자증가시자원 overhead 증가로전체셀 Throughput 감소 NO-CO: No coopration, CO-DM: Dynamic point Muting cooperation, CO-JT: Joint Transmission Cooperation *J. S. Kim, K. C. Go, S. K. Oh and J. H. Kim, "Performance Evaluation of BS Cooperative Communication in Networks-Wise," in Proc. ICUIMC 2013, Kota Kinabalu, Malaysia, Jan Jan. 19,

91 Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC) 181 3GPP Traffic Offloading Rel-8 Rel-9 Rel-10 Rel-11 Rel-12 Femto H(e)NB LIPA (local IP access) SIPTO (selected IP traffic offload) LIMONET (LIPA Mobility and SIPTO at the local network) Wi-Fi Seamless Handover MAPCON (multi access PDN connectivity) IFOM (IP flow mobility) NSWO (non-seamless WLAN offload) SMOG (S2a mobility based on GTP) SaMOG (S2a mobility based on GTP and WLAN access) LOBSTER (locationbased selection of gateway for WLAN) WLAN_NS(WLAN network selection for 3GPP terminals) FS_SAMOG FS_NBIFOM(networkbased IP flow mobility) FS_WORM(optimized offloading to WLAN in 3GPP RAT mobility) Policy aspects ANDSF (access network discovery and selection) ANDSF ISRP (inter-system routi ng policy) DIDA (data identification in ANDFS) BBAI (broadband forum access interworking) OPIIS (operator policies for IP interface selection) P4C (PCC control for supporting fixed broadband access networks) 김현숙, 3GPP Traffic Offload, FMC 포럼컨버젼스기술및표준워크샵,

92 Benefits of Traffic Offloading Mobile Operators Devices can connect directly to servers without going through core networks Mobile Operators can offer CDN(contents delivery network) services End-users RTTs can be expected to reduce and consequently throughput increases from the end-users viewpoint Service Provider Reduced RTTs and increased throughput can be expected by using storage in backhaul networks and providers can offer fact access to end-users as premium services to obtain extra revenues from the service providers view point Service providers can offer very rich and geographical oriented services by using storage in enbs NEC corporation, Mobile Traffic Offload: NEC s Cloud Centric Approach to Future Mobile Networks, Data Offloading Different data offloading techniques Path 1: WLAN solutions allow data offload directly to the Internet without utilizing service provider s resources Path 2 : Femtocells or H(e)NBs permit data offload via a Local Gateway(L-GW) Path 3 : maintaining home/enterprise related traffic local, via LIPA Path 4 : Data offload may be positioned at or above particular enbs for eutran Path 5 : Radio Network Controller (RNC) for UTRAN Konstantinos Samdanis, Tarik Taleb, Stefan Schmid, Traffic Offload Enhancements for eutran, IEEE COMMUNICATIONS SURVEYS & TUTORIAL,

93 LIPA & SIPTO Residential / Enterprise network LIPA L-GW H(e)NB Backhaul H(e)NB -GW Mobile Operator Core Network UE Key issues Legal interception QoS Single/multiple PDN support Deployed behind NAT Operator control for SIPTO 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10), LIPA & SIPTO Solution 1 variant 1 EPC L-GW HeNB Home network Home router/ NAT IP backhaul SeGW S5 S1-mme SGW S1-U MME S5 S11 PGW UE Local PDN GW (L-GW) function is collocated with the HeNB Paging of Idle mode UEs is triggered by sending the first downlink user packet or a dummy packet on S5 All other downlink user packets are buffered in the L-GW SeGW: security gateway, SGW: serving gateway, PGW: PDN gateway, MME: mobility management entity 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10),

94 LIPA & SIPTO Solution 1 variant 2 LIPA Traffic RAN L-S11 L-GW S1-MME S11 MME CN UE HeNB S1-U S-GW S5 P-GW CN Traffic L-GW can be either collocated with the HeNB or as a standalone node L-S11 interface between the L-GW and the MME is used to manage the session for LIPA traffic L-GW needs to be selected close to the HeNB Open issues Whether Mobility is supported/required for LIPA Whether the standalone L-GW architecture is supported for LIPA, and if it is, how 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10), LIPA & SIPTO Solution 2 variant 1 OPM Internet Home/Enterprise Network IP Backhaul MME EPC HeNB GW / NAT SeGW S1 -c S11 SGW S5 PGW S1-u NAT Function Block Routing Function Block UE Offload Processing Module (OPM) UEs are only required to activate one PDN connection for LIPA The OPM has the ability to drag/insert the LIPA traffic from/into PDN connection per operator policies (dst addr, Port #, etc.) 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10),

95 LIPA & SIPTO Solution 3 GGSN allocation to offload point LIPA and SIPTO are enabled by the SGSN selecting a GGSN that provides enhanced (e.g. shorter) traffic routeing capabilities located within the RAN The RAN providing the SGSN with the IP address(es) of one or more GGSNs that the RAN believes offers good traffic routeing capabilities The SGSN using the information from the RAN and HSS to potentially override the normal GGSN selection algorithm The SGSN using the permitted CSG/APN information and information supplied by the RAN to cause the release of a PDP context, if required by the service continuity restrictions, when the mobile leaves the CSG 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10), LIPA & SIPTO Solution 4 Selected IP Traffic Offload at Iu-PS CG LIG Ga UE NB RNC TOF SGSN GGSN Uu Iub Iu Iu Gn Iu Gi UE Uu HNB Iuh HNB GW Internet The traffic is offloaded after the RNC and before the SGSN in the Traffic Offload Function(TOF) Using Deep Packet Inspection(DPI) in the TOF a great level of granularity can be achieved TOF can be a separate entity, or collocated with RNC/HNB GW Gi VAS 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10),

96 LIPA & SIPTO Solution 5 SIPTO Traffic CN RAN L-PGW S5 S11 MME enb S1-U S-GW S5 P-GW UE CN Traffic Selected IP Traffic Offload solution based on local PDN GW selection The L-PGW is not co-located with the H(e)NB but is close by in the network The GW selection mechanism in the MME/SGSN takes into account the location of the user for the PDN connection/pdp context activation, and selects a GW that is geographically/topologically close 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10), LIPA & SIPTO Solution 6 UE LTE - Uu Local Network or Internet SGi GERAN/ UTRAN S1 - MME (H ome ) enb L- GW L- GW SGSN S3 MME S10 S1-U S11 HSS S6a Extension Tunnels S4 Serving Gateway S12 S5 Gx PDN Gateway PCRF added functionality added interface SGi Gi Rx Operator's IP Services UE Uu (H ome ) NB GERAN/ UTRAN Iu SGSN Gn GGSN L-GW is collocated with HeNB L-GW extension tunnel between the L-GW and the PDN GW 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10),

97 LIPA & SIPTO Conclusion on the LIPA architecture Solution 1 variant 1 is selected as the basis for LIPA to be included in normative specifications Supporting both a collocated and stand-alone L-GW as well as mobility (w/o mobility for Rel-10) Impacts to L-GW configurations LIPA_enabled flag (per APN and per CSG) in the user's subscription data stored in the HSS/HLR and transferred to the MME/SGSN (E-)RAB setup messages: addition of new correlation identifier (user plane L-GW TEID) Adding the transmission of the IP address of the L-GW in UEassociated signalling in the uplink, or, alternatively, DNS-based L-GW selection Possible Multicast support in the L-GW 3GPP TR V10.0.1, 3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10), Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC)

98 3GPP/Non-3GPP access network selection Access Network Selection for Offloading* HPLMN Non-3GPP Networks 3GPP Access S6a Serving Gateway S5 HSS Gxc Trusted Non- 3GPP IP Access Gx PDN Gateway Gxa PCRF epdg Gxb SWn SGi Rx Untrusted Non-3GPP IP Access Operator's IP Services (e.g. IMS, PSS, etc.) S6b SWm SWx SWa 3GPP AAA Server STa Procedure Get target system information by ANDSF UE connects to target system Authentication of UE Receive QoS information through PCRF Access to same PGW, and do binding update by PMIP Features PMIP: Anchor point PGW UE: LTE/Non-3GPP dual radio terminal Get address of PGW by saving address information to HSS S2c S2c UE S2c PMIP: Proxy Mobile IP PCRF: Policy and Charging Rules Function * 3GPP TS V12.1.0, Architecture enhancements for non-3gpp accesses, June ANDSF* Definition A framework for specifying and delivering access network selection policy to UE Purpose To assist UE to discover non-3gpp access networks Function Provide the information to UE ISMP: Network selection rules for a UE with no more than one active access network connection ISRP: Network selection rules for a UE with more than one active access network connection Discovery information: a list of networks that may be available in the vicinity of the UE UE location: geographical coordinates, a cellular cell or area, a WLAN location (SSID, BSSID) UE profile ANDSF: Access Network Discovery and Selection Function ISMP: Inter-System Mobility Policy ISRP: Inter-System Routing Policy * 3GPP TS V12.1.0, Access Network Discovery and Selection Function (ANDSF) Management Object (MO), June

99 Key issues related to WLAN network selection* Key issue 1 Support WLAN access through roaming agreements Current ANDSF support WLAN network selection policies based on SSID only Providing SSID preferences to UEs * 3GPP TS V1.0.0, WLAN network selection for 3GPP terminals, June Key issues related to WLAN network selection Solution for key issue 1 ANDSF policies with extended selection preferences Use Realms and/or OUIs instead of using SSID Realm/OUI identify and prioritize the discovered WLAN access networks» Ex) WLANs that interwork with Realm=PartnerX.com have the highest access priority OUI: Organizational Unique Identifier

100 Key issues related to WLAN network selection Key issue 2 Interaction between WLAN network selection and networkprovided policies for WLAN selection ANDSF rules are evaluated only after WLAN network selection is performed WLAN network selection priority list in the UE ANDSF rules cannot trigger the UE to select another WLAN access network Solution for key issue 2 WLAN selection based on ANDSF rules Use enhanced ISMP/ISRP rules SSID preferences Additional preferences» Realms (preferred service providers), OUIs, available backhaul bandwidth, connectivity capability, etc. 199 Key issues related to WLAN network selection Key issue 3 Delivery of consistent information for WLAN network selection Conflicting between the information from different sources or different management objects WFA Hotspot 2.0 specifications» WFA Hotspot 2.0: Provide seamless handoff without additional authentication Relevant components» ANDSF management object and USIM in 3GPP Key issue 4 Use WLAN load information for network selection ANDSF does not provide load information or congestion indication of WLAN networks: BSS load and backhaul parameters The policies for WLAN network selection may be enhanced to take these parameters into account

101 Key issues related to WLAN network selection Key issue 5 Use WLAN access network type and venue information for network selection Access network type: private, public, free, personal, emergency, etc. Venue information: venue type and name Help to identify the venue where WLAN network may be deployed (e.g. school, hotel, etc.) Key issue 6 Use connection capability during WLAN network selection Connection capability To provide information on the connection status within the WLAN network ANDSF does not take into account the connection capability of the WLAN networks WLAN network may block the IP flows of the UE 201 Key issues related to WLAN network selection Solution for key issue 3, 4, 5, and 6 Provide both ANDSF MO(with ISMP, ISRP etc.) and HS2.0 MO to the UE Example of HS2.0 MO: the load of the AP ANDSF MO enhanced with policies related to information elements available in HS2.0 Example: ISRP and ISMP as extensions to the prioritized access descriptions HS: Hotspot MO: Management Object

102 Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC) 203 D2D Communications What is D2D communication? Refer to the technologies that enable devices to communicate directly without an infrastructure of access points or base stations, and the involvement of wireless operators. Proximate discovery There is also a broad range of other potential applications that is contributing to industry enthusiasm and activity. * 3GPP TR V12.2.0, Feasibility study for Proximity Services (ProSe) (Release 12), * L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp ,

103 D2D vs. MTC D2D Device Type Cell phones or other devices in human-to-human communications MTC Machine-to-Machine communications without the involvement of human activities Communication Type Directly communication between devices Communication via infrastructure of LTE networks Related Spec. 3GPP TR GPP TS GPP TR Application Social matching Push advertising Multiplayer gaming Local voice service Contents sharing Metering Remote Maintenance/Control Health care Tracking & Tracing Security system * 3GPP TR V12.2.0, Feasibility study for Proximity Services (ProSe) (Release 12), * 3GPP TS V12.2.0, Service requirements for Machine-Type Communications (MTC);Stage 1(Release 12), * 3GPP TR V1.0.0, Machine-Type and other Mobile Data Applications Communications Enhancements (Release 12), Use Case and Business Model Local Voice Service D2D communications can be used to offload local voice traffic when two geographically proximate users want to talk on the phone. * L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp ,

104 Use case and business model Local Data Service D2D Communications can be used to provide local data service when two geographically proximate users or devices want to exchange data * L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp , Use case and business model Data Relay D2D Communications can be used to relay data for devices that are not directly cellular. * L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp ,

105 Introduction of Proximity Service Proximity Services (ProSe) Proximity services that identify mobiles in physical proximity and enable optimized communications between them ProSe Discovery A process that identifies that a UE is in proximity of another, using E-UTRA Open ProSe Discovery is ProSe Discovery without explicit permission from the UE being discovered Restricted ProSe Discovery is ProSe Discovery that only takes place with explicit permission from the UE being discovered. E-UTRA: Evolved Universal Terrestrial Radio Access 3GPP TR V Feasibility study for Proximity Services(ProSe), June, Introduction of Proximity Service ProSe Communication A communication between two UEs in proximity by means of a E-UTRAN communication path established between the UEs. The communication path could for example be established directly between the UEs or routed via local end(s) ProSe Group Communication a one-to-many ProSe Communication, between two or more UEs in proximity, by means of a common communication path established between the UEs. ProSe Broadcast Communication a one-to-all ProSe Communication, between all authorized UEs in proximity, by means of a common communication path established between the UEs. E-UTRAN: Evolved Universal Terrestrial Radio Access Network 3GPP TR V Feasibility study for Proximity Services(ProSe), June,

106 ProSe Communication Data paths for ProSe communication path ProSe E-UTRA Communication path could be established Directly path between the ProSe-enabled UEs using E-UTRA Locally routed path via local enb(s) ProSe-assisted WLAN direct communication path is established directly between the ProSe-enabled UEs using WLAN Direct mode E-UTRA: Evolved Universal Terrestrial Radio Access Locally-routed 211 ProSe Communication Control paths for ProSe communication path General Case The system can decide to perform ProSe Communication using control information exchanged between the UE, enb, EPC by the solid arrows The UEs can in addition exchange control signalling via the ProSe Communication path as shown by dashed arrow UEs served by the same enb UEs served by the different enbs

107 ProSe Communication Disaster Case (Public Safety UE) The Public Safety UEs can rely on pre-configured radio resources to establish and maintain the ProSe Communication Public safety Radio resource Management Function, which can reside in a Public Safety UE, can manage the allocation of radio resources for Public Safety ProSe Communication as shown with the dashed arrows With resource controller UE With pre-configured radio resources UEs without network support 213 General Use Case Restricted ProSe Discovery use case This use case describes a basic scenario for ProSe Discovery that can be used for any application A social networking application is used as an example Relationship(explicit permission)

108 General Use Case Open ProSe Discovery use case This use case describes a case in which UEs discover other UEs without permission by the discoverable UEs 215 General Use Case Discovery use case with roaming subscribers This use case describes discovery between UEs in different PLMNs under roaming condition

109 Public Safety Use Case ProSe discovery within network coverage This use case describes the scenario where a given UE discovers one or more other UEs while in LTE coverage, with ProSe Discovery always enabled ProSe discovery out of network coverage This use case describes the scenario where a given UE discovers one or more other UEs while out of E-UTRAN coverage, with ProSe Discovery always enabled Within network coverage Out of network coverage 217 Public Safety Use Case Can discover but not discoverable This use case describes the scenario where a given UE is able to discover other UEs, but is not discoverable by other UEs I don t want to be discovered

110 Public Safety Use Case ProSe relay This use case describes the scenario where a given UE acts as a communication relay for one or more UEs Without relay With relay 219 Public Safety Use Case ProSe group This use case describes the scenario where a user wants to communicate the same information concurrently to two or more users using ProSe Group Communications

111 Public Safety Use Case ProSe broadcast This use case describes the scenario where a given UE initiates a ProSe Broadcast Communication transmission to all UEs within transmission range 221 Reference model Architecture reference model Basic Concept 1. UE obtains configuration for direct services from Direct Services Provisioning Function (DPF) in a secure way 2. Direct Services Provisioning Function (DPF) exists in every PLMN 3. UE obtains configuration from Direct Services Provisioning Functions (DPFs) in PLMNs is authorised to perform direct discovery S Solution for direct discovery and communication, April, 2013 New reference points S141 : Reference point between UE and H-DPF or between UE and a DPF in a local PLMN where the UE is authorised by the H-DPF to perform direct services. It enables PLMN-specific direct services authorization S142 : Reference point between DPF in local PLMN and H-DPF. It enables PLMN-specific direct services authorization U2 : Reference point used for all the control and user plane information exchange needed in order to perform direct discovery between two UEs

112 Reference model Signaling flow for UE provisioning from DPF Authorisation for direct discovery 1. Is the UE allowed to announce in this PLMN? 2. Is the UE allowed to monitor in this PLMN? PLMN: Public Land Mobile Network MCC: Mobile Country Code FQDN: Fully Qualified Domain Name 223 Reference model Two roles for the UE in ProSe Discovery Announcing UE : The UE announces certain information that could be used from UEs in proximity that have permission to discover Monitoring UE : The UE that receives certain information that is interested in from other UEs in proximity

113 Public Safety Network What is Public Safety Network? Public safety networks provide communications for services like police, fire and ambulance Before: P25 and TETRA Poor interoperability of PTT(Push To Talk) Narrowband System Narrowband systems can t handle real-time video, detailed maps and blueprints, high-resolution, photographs and other files. LTE system can provide greater interoperability and the broadband capabilities to the public safety network P25: Project 25 TETRA: TErrestrial Trunked Radio *T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp , Why LTE? Greater interoperability and enhanced interagency cooperation: Sophisticated priority access mechanisms authorize and prioritize communication, so mission-critical data gets top priority. Standardized protocols and interfaces: Roaming capabilities are built in. Unprecedented broadband capabilities: LTE provides high capacity, allowing a wide variety of applications that have rich, multimedia content. It provides low latency, enabling real-time services (VoIP, video). Cost effective: LTE s simplified architecture lowers operating costs. It leverages a rich, open ecosystem from commercial networks. Highly reliable and secure: LTE offers advanced quality of service. It supports encryption/ciphering to enable secure communications. *Government Technology white paper, "A How-To Guide for LTE in Public Safety,"

114 Network Model *Government Technology white paper, "A How-To Guide for LTE in Public Safety," Feature & Requirements of Public Safety Networks Feature Requirements Group call A group call involves the communication of speech to all members of the group Data messaging can also be sent in parallel to speech QoS A segment of emergency group call speech will need higher priority to guarantee that it is not delayed by regular daily activities. Robustness It demands that alternative paths be available in the event of congestion and resource outages Direct Mode When part of a public safety network fails, the remainder of the network must continue to provide services to the greatest extent possible Direct mode is the ability of two or more public safety devices to communicate directly without the use of network infrastructure *T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp ,

115 LTE Enhancement for Public Safety Direct Communication over LTE ProSe (Proximity Services) Device-to-device discovery and communication DTD (Device-to-Device) Communication PTT: Push-To-Talk BM-SC: Broadcast multicast service center One-to-one, one-to-many/unicast, one-to-many/broadcast, and one-hop relay functionalities Group Communication over LTE GCSE (Group Communication System Enablers) Low-latency communication bearer setup Priority access for group calls QoS for group call bearers embms (enhanced Multimedia Broadcast Multicast Service) Broadcast capability Interface between PTT service application and BM-SC * 3GPP TR V12.2.0, Feasibility study for Proximity Services (ProSe) (Release 12), * 3GPP TR V0.2.0, Study on architecture enhancements to support Group Communication System Enablers for LTE (GCSE_LTE) (Release 12), Public Safety Spectrum **T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp ,

116 Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC) 231 Machine Type Communication(MTC) Machine Type Communication(MTC) Data communication with two or more objects Does not require human s participation during communication Provide network connection to most/all things Similar system : Wireless Sensor Network WPAN/WLAN/Ad-hoc based network Hard to provide QoS Mobility, end-to-end communication, compatibility problem It is not business area of network operators Install/maintenance by users hard to invest/maintain the system MTC makes new business area to network operators 3GPP TS v12.2.0, Service Requirements for Machine-Type Communications(MTC)(Release 12), 조수현, KT Vision : M2M Services and Technologies, KRNET 2011, 2011 년 6 월 27 일. 최상호, SKT Vision : M2M Based Mobile Service, KRNET 2011, 2011 년 6 월 27 일

117 MTC Applications Service Area Security Tracking & Tracing Payment Health Remote Maintenance/Control Metering Consumer Devices MTC Applications Surveillance systems, Backup for landline, Control of physical access(e.g. to buildings), Car/driver security Fleet management, Order management, Pay as you drive, Asset tracking, Navigation, Traffic information, Road tolling, Road traffic optimization/steering Point of sales, Vending machines, Gaming machines Monitoring vital signs, Supporting the aged or handicapped, Web access telemedicine points, Remote diagnostics Sensors, Lighting, Pumps, Valves, Elevator control Vending machine control, Vehicle diagnostics Power, Gas, Water, Heating, Grid control, Industrial metering Digital photo frame, Digital camera, ebook 3GPP TS v12.2.0, Service Requirements for Machine-Type Communications(MTC)(Release 12), Features/Requirements of MTC Requirement Low Mobility Time Controlled Small Data Transmissions Infrequent Mobile Terminated MTC Monitoring Secure Connection Group Based MTC Features Description The network must provide simplified mobility management The network shall provide mechanisms than can send or receive data only during defined time intervals The network shall support transmissions of small amounts of data with minimal network impact The network shall be able to maintain information on when the MTC Device is not reachable The network shall provide mechanisms to detect several MTC related events The network shall provide network security for connection The system shall be optimized to handle MTC Groups

118 Communication Scenarios MTC Devices communicating with one or more MTC Server MTC Devices communicating with each other 3GPP TS v12.2.0, Service Requirements for Machine-Type Communications(MTC)(Release 12), Comparison between Machine-to-Machine(M2M) Communication and MTC ETSI M2M Architecture 3GPP MTC Architecture Other M2M : Can use M2M Network and gateway Path to Access Networks Can be any standardized network system by 3GPP, TISAPN, IETF, etc 3GPP : No M2M Networks Devices directly attached to 3GPP Access Networks TISAPN:Telecommunications and Internet converged Services and Protocols PDN:Packet Data Network HSS:Home Subscriber Server enb:enodeb SM-SC:Short Message Service Centre HPLMN:Home Public Land Mobile Network RNC:Radio Network Controller PGW:PDN Gateway VPLMN:Visited Public Land Mobile Network BSC:Base Station Controller 유상근, 홍용근, 김형준, 스마트모바일서비스 M2M 기술및표준동향, 전자통신동향분석제 26권제2호, 2011년 4월

119 MTC in Release 10~11 Rel key issues were identified Signaling congestion control and overload control Key Issue MTC subscriptions Signaling congestion control IP addressing MTC device trigger MTC identifiers Group based optimization Description Activation/deactivation of MTC features MTC related signaling congestion and overload. MTC device using a private non-routable IPv4 address and thus not reachable by the MTC server. MTC server polls data from MTC devices Addressing issue due to the huge amount of MTC devices and shortage of MSISDNs Grouping of MTC devices for ease of control, management, charging facilities, etc., by the operators, and help in reducing redundant signaling. MTC devices frequently send or receive only small Online small data transmission amounts of data. MTC devices infrequently send or receive only small Offline small data transmission amounts of data. MTC monitoring Monitoring of MTC devices in locations with high risk. Low Power Consumption Battery power saving for MTC devices. MTC devices communicating Common service requirements for communication with one or more MTC servers between MTC devices and MTC servers. Low mobility MTC device does not move frequently. Data transmission is only performed in a predefined Time controlled time period. Decoupling MTC server from MTC server may be deployed outside of the mobile 3GPP architecture network. Potential overload issues caused Imbalance of signaling vs. data traffic in the Visited by roaming MTC devices Public Land Mobile Network (VPLMN). 3GPP TS v12.2.0, Service Requirements for Machine-Type Communications(MTC)(Release 12), Andreas Kunz, Machine Type Communications in 3GPP From Release 10 to Release 12, GLOBECOM 2012 ONIT WS, Dec Rel-11 IP addressing MTC identifiers Device triggering Signalling Congestion and Overload Control Numerous devices make congestion even though they transmit small data Solution Low access priority Attach with IMSI at PLMN change Periodic PLMN search time limit Handling of the invalid USIM state UE message can be rejected, usage of waiting/back-off timers UE does not perform TAU with GUTI at PLMN change Minimum time between searches for preferred PLMN is increased PLMN forbidden lists are kept even if UE is switched off and on IMSI(International Mobile Subscriber Identity) : 가입자 ID( 전화번호 ) PLMN(Public Land Mobile Network) : 네트워크식별번호 TAU(Tracking Area Update) GUTI(Globally Unique Temporary Identifier) : 사용자의임시 ID

120 MTC Device Identifiers/Addressing Objective Assign ID and address to MTC devices to enable a MTC server in a public addressing domain to send messages to a MTC device in a private addressing domain Solution Identifier 15-digit IMSI telephone number for large-scale deployment Addressing IPv6 addressing IPv4 addressing with private IPv4 domain Private IPv4 Address Space IPv4 Address Space MTC Device MNO MTC Server MNO : Mobile Network Operator 239 MTC in Release 12 Rel-12 Triggering enhancements Group based features Small data transmission Monitoring UE power consumptions optimizations Key Issue MTC subscriptions Signaling congestion control IP addressing MTC device trigger MTC identifiers Group based optimization Description Activation/deactivation of MTC features MTC related signaling congestion and overload. MTC device using a private non-routable IPv4 address and thus not reachable by the MTC server. MTC server polls data from MTC devices Addressing issue due to the huge amount of MTC devices and shortage of MSISDNs Grouping of MTC devices for ease of control, management, charging facilities, etc., by the operators, and help in reducing redundant signaling. MTC devices frequently send or receive only small Online small data transmission amounts of data. MTC devices infrequently send or receive only small Offline small data transmission amounts of data. MTC monitoring Monitoring of MTC devices in locations with high risk. Low Power Consumption Battery power saving for MTC devices. MTC devices communicating wit Common service requirements for communication h one or more MTC servers between MTC devices and MTC servers. Low mobility MTC device does not move frequently. Data transmission is only performed in a predefined Time controlled time period. Decoupling MTC server from 3G MTC server may be deployed outside of the mobile PP architecture network. Potential overload issues caused Imbalance of signalling vs. data traffic in the Visited by roaming MTC devices Public Land Mobile Network (VPLMN)

121 Outlook of MTC in 3GPP Release 12 Triggering enhancements intended for device triggering by using reference points between MTC-IWF and serving nodes (i.e., SGSN, MME, and MSC), as well as triggering efficiency optimizations. Group based features optimizations to a group of MTC UEs that share one or more MTC features. Small data transmission intended for use with MTC UEs that send or receive small amounts of data. Also, frequent small data transmission will be considered. Monitoring intended for monitoring MTC UE related events such as loss of connectivity, change of the location of MTC UE, etc. UE power consumptions optimizations intended for optimizations to prevent battery drain of MTC UEs. MTC-IWF : Interworking function between (external) MTC Server and operator core network 241 Summary

122 Summary 3GPP LTE Network Architecture User Plane Protocol Packet Data Convergence Protocol / Radio Link Control / Medium Access Control Control Plane Protocol Radio Resource Control / Mobility control / Radio Resource Management LTE-Advanced Features Heterogeneous Networks / Carrier Aggregation / CoMP Release 12 Issues Offloading / WLAN Network Selection / Device-to-Device Communications / Machine Type Communication 243 Thank you! Q & A