INTRODUCTION TO LTE ECE 2526 - MOBILE COMMUNICATION Monday, 25 June 2018 1
WHAT IS LTE? 1. LTE stands for Long Term Evolution and it was started as a project in 2004 by the Third Generation Partnership Project (3GPP). 2. LTE evolved from an earlier 3GPP system known as the Universal Mobile Telecommunication System (UMTS), 3. UMTS, on the other hand, had evolved from the Global System for Mobile Communications (GSM). 4. LTE is an all IP based network, supporting both IPv4 and IPv6 4 th Generation LTE 3 rd Generation CDMA2000, WCDMA, UMTS 2 nd Generation GSM, DAMPS 1 st Generation AMPS, ETACS 2
MOTIVATION FOR LTE 1. By 2004, there was a rapid increase of mobile data usage and emergence of new applications such as MMOG (Multimedia Online Gaming), mobile TV, Web streaming contents, etc. 2. Long-Term Evolution (LTE) was proposed as a set of standards to support movement from 3 rd to 4 th generation mobile communication. 3
GOALS OF LTE The Goals of LTE were to provide: 1. Higher data rates (300Mbps peak downlink and 75 Mbps peak uplink) 2. Low latency (Time required to connect to the network or enter power saving states). This is necessary to support gaming and interactive data transfer 3. Packet optimized radio access technology 4. Seamless mobility; and 5. Higher Quality of Service (QoS). 4
MILESTONES IN THE DEVELOPMENT OF LTE 2000 - UMTS/WCDMA 2002 - High Speed Downlink Packet Access (HSDPA) 2005 - High Speed Uplink Packet Access (HSUPA) 2007 - DL MIMO, IMS (IP Multimedia Subsystem) 2004 - Work started on LTE specification 2008 Specifications finalized and approved with UMTS Release 8 2010 - First deployment 5
LTE SPECIFICATIONS Data type PARAMETER DETAILS All packet switched data (voice and data). No circuit switched. Peak downlink speed Peak uplink speeds (Mbps) Channel bandwidths (MHz) Duplex schemes Mobility Latency Spectral efficiency 100 (SISO), 172 (2x2 MIMO), 326 (4x4 MIMO) 50 (QPSK), 57 (16QAM), 86 (64QAM) 1.4, 3, 5, 10, 15, 20 FDD and TDD 0-15 km/h (optimised), 15-120 km/h (high performance) Idle to active less than 100ms Small packets ~10 ms Downlink: 3-4 times Rel 6 HSDPA Uplink: 2-3 x Rel 6 HSUPA Access schemes Orthogonal Frequency Division Multiple Access (OFDMA) - Downlink Frequency Division Multiple Access (SC-FDMA) - Uplink Modulation types supported QPSK, 16QAM, 64QAM (Uplink and downlink) 6
COMPARISON OF PERFORMANCE 3RD & 4TH GENERATION WCDMA (UMTS) HSPA HSDPA / HSUPA HSPA+ LTE Max downlink 384 kbps 14 Mbps 28 Mbps 100Mbps speed Max uplink speed 128 kbps 5.7 Mbps 11 Mbps 50 Mbps Latency round trip time approx Approx years of initial roll out 150 ms 100 ms 50ms (max) ~10 ms 2003 / 4 2005 / 6 HSDPA 2007 / 8 HSUPA 2008 / 9 2009 / 10 Access methodology CDMA CDMA CDMA OFDMA / SC- FDMA 7
LTE HIGH LEVEL ARCHITECTURE The high-level network architecture of LTE is comprised of following three main components: 1. The User Equipment (UE) 2. The Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) 3. The Evolved Packet Core (EPC) Packet Switched Packet Switched 8
(a) 3G Architecture (b) LTE Architecture
E-UTRAN OPERATING FREQUENCY BANDS 10
USER EQUIPMENT 1. The internal architecture of the user equipment for LTE is the same as the one used by UMTS and GSM. 2. The mobile equipment comprised of the following modules: a) Mobile Termination (MT) : This handles all the communication functions. b) Terminal Equipment (TE) : This terminates the data streams. c) Universal Subscriber Identity Module (USIM): Stores user-specific data including user's phone number, home network identity and security keys etc. Similar to 2G and 3G. 11
ARCHITECTURE OF E-UTRAN The Evolved UTRAN (E-UTRAN) handles the radio communications between the User Equipment (UE) and the Evolved Packet Core (EPC). Evolved Node B Evolved Packet Core 12
EVOLVED BASE STATION (enodeb) 1. The Evolved base stations (enodeb or enb) controls the mobiles in one or more cells. 2. The base station that is communicating with a mobile is known as its serving enb. 13
HOME enb 1. Home enb (HeNB) is a base station that has been purchased by a user to provide femtocell coverage within the home or enterprise. 2. A home enb belongs to a closed subscriber group (CSG) and can only be accessed by mobiles with a USIM that also belongs to the closed subscriber group. 3. The coverage area of a HeNB is called a Femto cell. 14
LTE FEMTO CELLS 1. LTE Femto cells are low power cellular base stations that employ licenced spectrum. 2. They are deployed in residential, enterprise, metropolitan hot spots. 3. They provide excellent user experience through enhanced coverage, performance and location-based services. 15
EVOLVED PACKET CORE (EPC) The Evolved Packet Core (EPC) consists of the following: 1. Mobility Management Entity (MME) 2. Home Subscriber Server (HSS) 3. Packet Data Network Gateway (P- GW): 4. Serving Gateway (S-GW): Acts as a router by forwards data between the base station and the P-GW. Public Data Networks 16
Mobility Management Entity (MME) Controls the high-level operation of the mobile by interpreting signalling messages by using information from the Home Subscriber Server (HSS). S10 Links to other MMEs Home Subscriber Server (HSS) central database that contains information about all the network operator's subscribers Serving Gateway (S-GW) Acts as a router by forwards data between the base station and the P-GW. Packet Data Network Gateway (PGW) communicates with the outside world using SGi interface. Each packet data network is identified by an Access Point Name (APN).
SUMMARY OF FUNCTIONS OF E-UTRAN & EPC E-UTRAN EPC enodeb Intercell route management Radio Bandwidth Control Connection mobility control Radio Admission Control enb signal strength measurements, Configuration and control Dynamic Resource Allocation MME Network Access Security Idle State Mobility Handling EPS Bearer Control S-GW Mobility Anchoring S-GW UE IP Address Allocation Packet filtering (Firewall) 18
LTE NETWORK AREA An LTE network area is divided into three different types of geographical areas, i.e 1. MME Pool Area: Area where a UE can move without a change of serving MME. 2. S-GW Service Area: An area served a serving gateway (S-GW). The UE can move in this area without a change of S-GW. 3. Tracking Area: Smaller areas used to track the locations of mobiles that are in idle mode. Same as a Location Area(LA) in GSM. 19
LTE RADIO PROTOCOL ARCHITECTURE The radio protocol architecture for LTE is made of two main parts, i.e CONTROL PLANE The radio resource control (RRC) protocol writes the signalling messages that are exchanged between the base station (enodebs) and the UE. USER PLANE The application creates data packets that are processed by protocols such as TCP, UDP and IP 20