Timing & Synchronization in Wireless Infrastructure

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Ferdinand Anderson
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Timing & Synchronization in Wireless Infrastructure Harpinder Singh Matharu

4 Expenditure / Revenue Revenue & CAPE/ OPE disparity CAPE/OPE Lower Cost per bit Revenue New Business Models Rapid increase in Data Traffic 2G (GSM/CDMA/UMTS) +3G/4G (HSPA, WiMA, LTE, LTE Advanced) Time Maximizing spectrum utilization Ease of network deployment & management Leveraging value/ intelligence in the network Copyright 2010 ilinx Page 4

5 Base station Architectural shift Mast Mounted RRH Mast Mounted RRH CPRI/ OBSAI Traditional Centralized BTS CPRI/ OBSAI CPRI/ OBSAI Remote Radio Heads Shift from co-located to distributed BTS Architecture Copyright 2010 ilinx

6 Remote Radio Heads enable Power Savings Antenna Array Antenna Array Remote Radio Head Channel Cards Radio Cards After feeder loss Power received 30 W Channel Cards No Feeder loss PA 30W Coaxial Feeder Cable Short length ~3dB Loss Fiber Long haul No Loss Traditional Base Station Cabinet Power Available 60 W Significant CAPE/ OPE Impact Distributed Base Station Remote Radio Heads (RRH) Fiber replaces Coaxial Cable for significant CAPE/ OPE Savings Copyright 2010 ilinx

7 Standardization of Radio Interface BASEBAND REMOTE RADIO HEAD N E T W O R K LAYER 2 & 3 + NIC LAYER 1 - PHY ANALOG CARD B A C K H A U L CONTROL CARD FIBER DIGITAL FRONT END CPRI/OBSAI INTERFACE Copyright 2010 ilinx Page 7

8 Radio Interface Standards Drivers & Benefits Drivers: Reduce BTS cost, power, and complexity Make module level expertise & ecosystem viable Benefits: Off-the-shelf modules Lower cost and shorter time to market Faster technology / innovation adoption Copyright 2010 ilinx

10 Timing & Synchronization Challenge in RRH Remote Radio Heads GPS Remote Radio Heads Core Network IEEE1588/ NTP Base station Timing & Synchronization I/Q Data Control Messaging Tight timing & synchronization needs to enable Remote Radio Heads Copyright 2010 ilinx Page 10

11 System Timing Requirements 1 0.5ms U-Plane IQ Data Round Trip Delay = 5 µs enodeb System Frame = 10 ms ANTENNA LTE TDD/ UTRA-TDD T-R Switch = ns Control Card (Clock) MODEM Or Channel Card Link Delay Accuracy <= ns REMOTE RADIO HEAD REMOTE RADIO HEAD REMOTE RADIO HEAD BTS Channel Card Chassis Fiber Link (10-20 km) Daisy Chained Remote Radio Heads Copyright 2010 ilinx Page 11

12 Transmit Diversity/ MIMO Timing Requirements ANTENNA Control Card (Clock) MODEM Or Channel Card REMOTE REMOTE RADIO RADIO HEAD HEAD BTS Channel Card Chassis Fiber Link (10-20 km) Phase Difference <= 65 ns Sources: 3GPP / Copyright 2010 ilinx Page 12

13 CPRI Protocol Terminology ANTENNA ANTENNA RADIO EQUIPMENT CONTROLLER (REC) BASEBAND CHASSIS OPTICAL OR ELECTRICAL LINK D0 D1 D2 RADIO EQUIPMENT (RE A) OPTICAL OR ELECTRICAL LINK RADIO EQUIPMENT (RE B ) CPRI (MASTER) D0 D1 D2 CPRI (Slave) CPRI (Master) D0 D1 D2 CPRI (Slave) Packets flow between REC and RE A Packets flow between REC and RE B Link Speeds = 0.6; 1.2; 2.4; 4.9; 6.144G + 9.8G (spec expected to be released soon) Copyright 2010 ilinx Page 13

14 CPRI Protocol Frame Synchronization CONTROL DATA FRAME DELIMITER SYMBOL WORDS BASIC FRAME NUMBER ( ns) NODE B FRAME NUMBER HFN SFN SFN 5 BFN 0 BFN HYPER-FRAME (66.67 µs) HF 0 HF Control Sub Channels in a Hyper-frame SYSTEM FRAME ( 10 ms) Copyright 2010 ilinx

15 TRANSCEIVERS CPRI Protocol Clock Synchronization Remote Radio Head PLL & VCO/ VCO REFERENCE CLOCK +/ ppm with Master Clock RECOVERED CLOCK CLOCK DATA RECOVERY (CDR) Electrical or Optical Interface CPRI link similar to synchronous Ethernet in Clock Recovery Copyright 2010 ilinx Page 15

16 TDM (I/Q Data & Control) TRANSCEIVERS CPRI Protocol Link Delay Accuracy Challenge Application Layer Air Interface Mapping Scheme / Multi Air Interface Mapping Control Messaging I/Q Data Framing ROUND TRIP DELAY MEASUREMENT RECEIVE FIFO Electrical or Optical Interface Round Trip Delay Accuracy of < = ns fairly challenging Copyright 2010 ilinx Page 16

17 Ethernet over CPRI *p 3 5 P Up to 211 Mbps Bandwidth ETHERNET PHY Control Sub Channels in a Hyperframe Could spare Ethernet bandwidth be used for PTP to reduce timing cost? Copyright 2010 ilinx Page 17

19 Fiber Sharing CPRI over Carrier Ethernet? Network Convergence Control Card (Clock) MODEM Or Channel Card REMOTE RADIO HEAD REMOTE RADIO HEAD REMOTE RADIO HEAD FIBER SHARING Currently dedicated fiber link being laid out for Radio Interface Copyright 2010 ilinx Page 19

Station IEEE 1588 Could PTP + Power over

20 Small Cell Connectivity PTP plus Ethernet over Power? MODEM RADIO HEAD Core Network IEEE1588/ NTP Tower Mounted Integrated Small Base Station IEEE 1588 Could PTP + Power over Ethernet be used in the last segment? Copyright 2010 ilinx Page 20

21 Summary Mobile Network witnessing exponential growth Architectural innovations to keep CAPE /OPE in bounds Standardization important for healthy ecosystem Challenges & Opportunities abound Copyright 2010 ilinx Page 21

Access network systems for future mobile backhaul networks

Access network systems for future mobile backhaul networks Nov. 6, 2012 Seiji Yoshida NTT Network Technology Laboratories NTT Corporation 1 Outline Mobile Traffic Growth in Japan Future Mobile Base Station