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© Copyright 2010 Xilinx 11/4/2010 Timing & Synchronization in Wireless Infrastructure Harpinder Singh Matharu Senior Product Manager, Comms Division, Xilinx
© Copyright 2010 Xilinx11/4/2010
Timing & Synchronization in Wireless
Infrastructure
Harpinder Singh MatharuSenior Product Manager, Comms Division, Xilinx
© Copyright 2010 XilinxPage 2
Topics
Wireless Infrastructure Market Trends
Timing & Synchronization in Base stations
Challenges & Opportunities
© Copyright 2010 Xilinx
Mobile Network witnessing rapid growth
Page 3
• Heterogeneous Network
• Backhauling & Synchronization
a challenge Traditional Network Investment – 80%
Mobile
Network–
20%
Trend
© Copyright 2010 XilinxPage 4
Revenue & CAPEX/ OPEX disparity
Time
Exp
en
ditu
re / R
eve
nu
e
2G (GSM/CDMA/UMTS) +3G/4G (HSPA, WiMAX, LTE, LTE Advanced)
CAPEX/OPEX
Revenue
• Maximizing spectrum utilization
• Ease of network deployment & management
• Leveraging value/ intelligence in the network
Rapid increase in Data Traffic
New Business
Models
Lower Cost
per bit
© Copyright 2010 Xilinx
Base station Architectural shift
Traditional
Centralized BTSRemote Radio Heads
Mast
Mounted
RRH
Shift from co-located to distributed BTS Architecture
Mast
Mounted
RRH
CPRI/ OBSAI
CPRI/ OBSAI CPRI/ OBSAI
© Copyright 2010 Xilinx
Remote Radio Heads enable Power Savings
Channel Cards Radio Cards
Traditional Base Station
Cabinet
Antenna Array
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Coaxial Feeder Cable
• Short length
• ~3dB Loss
Power Available – 60 W
After feeder loss
Power received – 30 WChannel Cards
Distributed Base Station
Remote Radio Heads
(RRH)
Antenna Array
X
X
X
X
X
X
X
X
X
Fiber
• Long haul
• No Loss
No Feeder loss
PA – 30W
Remote Radio Head
Fiber replaces Coaxial Cable for significant CAPEX/ OPEX Savings
Significant CAPEX/
OPEX Impact
© Copyright 2010 Xilinx
Standardization of Radio Interface
Page 7
BASEBAND
LAYER 1 - PHYLAYER 2 & 3 + NIC
CONTROL CARD
NETWORK
BACKHAUL
DIGITAL FRONT END
ANALOG CARD
REMOTE RADIO HEAD
FIBER
CPRI/OBSAIINTERFACE
© Copyright 2010 Xilinx
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 XilinxPage 9
Topics
Wireless Infrastructure Market Trends
Timing & Synchronization in Base stations
Challenges & Opportunities
© Copyright 2010 Xilinx
Timing & Synchronization Challenge in RRH
Page 10
Remote
Radio
Heads
Remote
Radio
Heads
GPS
Core NetworkBase station
IEEE1588/ NTPTiming & Synchronization
I/Q Data
Control Messaging
Tight timing & synchronization needs to enable Remote Radio Heads
© Copyright 2010 Xilinx
System Timing Requirements
Page 11
BTS Channel Card Chassis
ANTENNA
Control
Card
(Clock)
MODEM
Or
Channel
Card
Fiber Link (10-
20 km)
REMOTE
RADIO
HEAD
REMOTE
RADIO
HEAD
REMOTE
RADIO
HEAD
Daisy Chained Remote Radio Heads
U-Plane IQ Data Round
Trip Delay = 5 µs
LTE TDD/
UTRA-TDD
TX-RX Switch =
16.276 ns
1
0.5ms
2 3 4 5 6 7 8 9 10
eNodeB System Frame = 10 ms
Link Delay
Accuracy <=
8.138 ns
© Copyright 2010 Xilinx
Transmit Diversity/ MIMO Timing Requirements
Page 12
BTS Channel
Card Chassis
REMOTE
RADIO
HEAD
ANTENNA
Phase Difference <= 65 nsSources: 3GPP – 25.104/ 36.104
Control
Card
(Clock)
MODEM
Or
Channel
Card
Fiber Link (10-20 km)
REMOTE
RADIO
HEAD
© Copyright 2010 Xilinx
CPRI Protocol Terminology
Page 13
CPRI
(Slave)
D2D1D0
CPRI
(MASTER)
RADIO EQUIPMENT
CONTROLLER (REC)
BASEBAND CHASSIS
D2D1D0
CPRI
(Master)
RADIO
EQUIPMENT
(RE B )
D2D1D0
RADIO EQUIPMENT
(RE A)
OPTICAL
OR
ELECTRICAL LINK
Packets flow between REC and RE A
Packets flow between REC and RE B
OPTICAL
OR
ELECTRICAL LINK
ANTENNA
CPRI
(Slave)
ANTENNA
Link Speeds = 0.6; 1.2; 2.4; 4.9; 6.144G
+ 9.8G (spec expected to be released
soon)
© Copyright 2010 Xilinx
CPRI Protocol Frame Synchronization
63
1
2
3
3
210
0
5
6
62
Control Sub Channels in a Hyper-frame
NODE B FRAME
NUMBER
HFN SFN SFN
FRAME DELIMITER
SYMBOL
0 1 – 15 WORDS
CONTROL DATA
BASIC FRAME NUMBER (260.42 ns)
BFN 0 BFN
255
HYPER-FRAME (66.67 µs)
HF 0 HF
149
SYSTEM FRAME ( 10 ms)
© Copyright 2010 Xilinx
CPRI Protocol – Clock Synchronization
Page 15
TR
AN
SC
EIV
ER
S
Ele
ctric
al o
r Op
tica
l
Inte
rface
CLOCK DATA
RECOVERY
(CDR)
RECOVERED
CLOCK
PLL
&
VCO/ VCXO
REFERENCE CLOCK
+/- 0.002 ppm with Master Clock
CPRI link similar to synchronous Ethernet in Clock Recovery
Remote Radio Head
© Copyright 2010 Xilinx
CPRI Protocol – Link Delay Accuracy Challenge
Page 16
TR
AN
SC
EIV
ER
S
RECEIVE
FIFO
TD
M (
I/Q D
ata
& C
ontr
ol)
I/Q Data
Framing
Control
Messaging
Air Interface
Mapping
Scheme /
Multi Air
Interface
MappingApplication
Layer
Ele
ctric
al o
r Op
tica
l
Inte
rface
ROUND TRIP
DELAY
MEASUREMENT
Round Trip Delay Accuracy of < = 16.276 ns fairly challenging
© Copyright 2010 Xilinx
Ethernet over CPRI
Page 17
63
1
2
3
3
210
0
5
P
62
Control Sub Channels in a Hyperframe
ETHERNET
PHY
Up to
211 Mbps
Bandwidth
*p
Could spare Ethernet bandwidth be used for PTP to reduce timing cost?
© Copyright 2010 XilinxPage 18
Topics
Wireless Infrastructure Market Trends
Timing & Synchronization in Base stations
Challenges & Opportunities
© Copyright 2010 Xilinx
Fiber Sharing – CPRI over Carrier Ethernet?
Network Convergence
Page 19
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 Xilinx
Small Cell Connectivity
PTP plus Ethernet over Power?
Page 20
Core Network
IEEE1588/ NTP
MODEMRADIO
HEAD
Tower Mounted
Integrated Small
Base Station
IEEE 1588 – Could PTP + Power over Ethernet be used in the last segment?
© Copyright 2010 XilinxPage 21
Summary
Mobile Network witnessing exponential growth
Architectural innovations to keep CAPEX /OPEX in bounds
Standardization important for healthy ecosystem
Challenges & Opportunities abound
