Timing & Synchronization in Wireless Infrastructure

Harpinder Singh Matharu Senior Product Manager, Comms Division, Xilinx

11/4/2010 © Copyright 2010 Xilinx Topics

. Wireless Infrastructure Market Trends

. Timing & Synchronization in Base stations

. Challenges & Opportunities

© Copyright 2010 Xilinx Page 2 Mobile Network witnessing rapid growth

Trend • Heterogeneous Network Mobile Traditional Network Investment – 80% Network– • Backhauling & Synchronization 20% a challenge

© Copyright 2010 Xilinx Page 3 Revenue & CAPEX/ OPEX disparity

Lower Cost CAPEX/OPEX per bit

New Business Models Revenue

Rapid increase in Data Traffic Expenditure / / Revenue Expenditure

2G (GSM/CDMA/UMTS) +3G/4G (HSPA, WiMAX, LTE, LTE Advanced) Time

• Maximizing spectrum utilization • Ease of network deployment & management • Leveraging value/ intelligence in the network

© Copyright 2010 Xilinx Page 4 Base station Architectural shift

Mast Mast Mounted Mounted RRH RRH

CPRI/ OBSAI

Traditional CPRI/ OBSAI CPRI/ OBSAI Centralized BTS Remote Radio Heads

Shift from co-located to distributed BTS Architecture

© Copyright 2010 Xilinx Remote Radio Heads enable Power Savings

Antenna Array Antenna Array

X X X X X X X X X X X X X X X X X Remote Radio Head X X X X X X X X X X After feeder loss No Feeder loss Radio Cards Channel Cards Power received – 30 W PA – 30W Channel Cards Coaxial Feeder Cable Fiber • Short length • Long haul • ~3dB Loss • No Loss

Power Available – 60 W Distributed Base Station Traditional Base Station Significant CAPEX/ OPEX Impact Remote Radio Heads Cabinet (RRH)

Fiber replaces Coaxial Cable for significant CAPEX/ OPEX Savings

© Copyright 2010 Xilinx Standardization of Radio Interface

BASEBAND REMOTE RADIO HEAD ANALOG CARD N LAYER 2 & 3 + NIC LAYER 1 - PHY E T W O R K

B A C DIGITAL FRONT END K H A CONTROL CARD U L FIBER

CPRI/OBSAI INTERFACE

© Copyright 2010 Xilinx Page 7 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 Xilinx Topics

. Wireless Infrastructure Market Trends

. Timing & Synchronization in Base stations

. Challenges & Opportunities

© Copyright 2010 Xilinx Page 9 Timing & Synchronization Challenge in RRH

Remote Radio Heads

GPS Remote Radio Heads

Base station Core Network IEEE1588/ NTP Timing & Synchronization I/Q Data Control Messaging Tight timing & synchronization needs to enable Remote Radio Heads

© Copyright 2010 Xilinx Page 10 System Timing Requirements

0.5ms 1 2 3 4 5 6 7 8 9 10

eNodeB System Frame = 10 ms U-Plane IQ Data Round Trip Delay = 5 µs ANTENNA

MODEM LTE TDD/ Control Link Delay Or Card Accuracy <= UTRA-TDD Channel REMOTE REMOTE REMOTE (Clock) TX-RX Switch = Card 8.138 ns RADIO RADIO RADIO 16.276 ns HEAD HEAD HEAD

Fiber Link (10- 20 km) BTS Channel Card Chassis Daisy Chained Remote Radio Heads

© Copyright 2010 Xilinx Page 11 Transmit Diversity/ MIMO Timing Requirements

ANTENNA

MODEM Control Or Card REMOTE Channel REMOTE (Clock) RADIO Card RADIO HEADHEAD

BTS Channel Fiber Link (10-20 km) Card Chassis Phase Difference <= 65 ns Sources: 3GPP – 25.104/ 36.104

© Copyright 2010 Xilinx Page 12 CPRI Protocol Terminology

ANTENNA ANTENNA

OPTICAL OR OPTICAL RADIO RADIO EQUIPMENT RADIO EQUIPMENT CONTROLLER (REC) ELECTRICAL LINK OR EQUIPMENT (RE A) ELECTRICAL LINK BASEBAND CHASSIS (RE B ) D0 D1 D2

CPRI CPRI CPRI (Master) CPRI (MASTER) (Slave) (Slave) D0 D1 D2 D0 D1 D2

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 Xilinx Page 13 CPRI Protocol Frame Synchronization

CONTROL DATA FRAME DELIMITER 0 1 2 3 SYMBOL 0 0 1 – 15 WORDS 1 NODE B FRAME HFN SFN SFN NUMBER 2 BASIC FRAME NUMBER (260.42 ns) 3 5 6 BFN 0 BFN 255

HYPER-FRAME (66.67 µs)

62 63 HF 0 HF 149 Control Sub Channels in a Hyper-frame

SYSTEM FRAME ( 10 ms)

© Copyright 2010 Xilinx CPRI Protocol – Clock Synchronization

Remote Radio Head Electrical Electrical Optical or REFERENCE CLOCK

PLL +/- 0.002 ppm with Master Clock Interface & VCO/ VCXO

RECOVERED TRANSCEIVERS CLOCK CLOCK DATA RECOVERY (CDR)

CPRI link similar to synchronous Ethernet in Clock Recovery

© Copyright 2010 Xilinx Page 15 CPRI Protocol – Link Delay Accuracy Challenge

Air Interface Mapping Scheme / Electrical Optical or

Multi Air Interface ROUND TRIP Application Interface I/Q Data DELAY Layer Mapping Framing MEASUREMENT

Control TRANSCEIVERS Messaging

TDM (I/Q Data & Control) Data (I/Q Control) & TDM RECEIVE FIFO

Round Trip Delay Accuracy of < = 16.276 ns fairly challenging

© Copyright 2010 Xilinx Page 16 Ethernet over CPRI

0 1 2 3 0 1

2 *p 3 5

Up to 211 Mbps Bandwidth ETHERNET P PHY

62 63

Control Sub Channels in a Hyperframe

Could spare Ethernet bandwidth be used for PTP to reduce timing cost?

© Copyright 2010 Xilinx Page 17 Topics

. Wireless Infrastructure Market Trends

. Timing & Synchronization in Base stations

. Challenges & Opportunities

© Copyright 2010 Xilinx Page 18 Fiber Sharing – CPRI over Carrier Ethernet? Network Convergence

MODEM Control Or Card Channel REMOTE REMOTE REMOTE (Clock) Card RADIO RADIO RADIO HEAD HEAD HEAD

FIBER SHARING – Currently dedicated fiber link being laid out for Radio Interface

© Copyright 2010 Xilinx Page 19 Small Cell Connectivity PTP plus Ethernet over Power?

RADIO MODEM HEAD

IEEE1588/ NTP Tower Mounted Core Network Integrated Small Base Station

IEEE 1588 – Could PTP + Power over Ethernet be used in the last segment?

© Copyright 2010 Xilinx Page 20 Summary

. Mobile Network witnessing exponential growth

. Architectural innovations to keep CAPEX /OPEX in bounds

. Standardization important for healthy ecosystem

. Challenges & Opportunities abound

© Copyright 2010 Xilinx Page 21