MCMA Frontend

1
MCMA Front-end

• Danijela Cabric, Tina Smilkstein, Susan H.
  Mellers
• Prof. Robert W. Brodersen
• Berkeley Wireless Research Center
• Winter Retreat 2004

2
Introduction

• Benefits of multiple-antenna systems
• Increase in data rate
• Improvement of reliability against channel
  fluctuations
• Interference suppression and avoidance
• Goal of this project Prototype of a transmission
  system
• 1 Gbit/s data rate
• Spectrum efficiency of 40-50 bit/s/Hz (802.11a
  4.8 bit/s/Hz)
• Multiple antennas (MIMO), multiple carriers
  (OFDM)
• Parallel front-end with up to 16 antennas
• Testbed for different multiple-antenna algorithms
• Necessary prototype components
• Simulation framework for algorithm development
• Digital baseband processing design
• Prototype platform
• Parallel RF front-end

3
MCMA System Overview

• Fully parallel front-end with up to 16
  transmit/receive antennas
• Different MEA algorithms like Singular Value
  Decomposition (SVD), Beam-forming

Fiber Optic Link
Parallel RF Front-End
Digital Baseband Processing on BEE Prototype
Platform
transp.
transp.
1
1
2
2
DataBits
Coding andModulation
N
M
Transmitter
Multiple-AntennaProcessing
Multiple-CarrierProcessing
Receiver
transp.
transp.
1
1
2
2
Demodulationand Decoding
DataBits
N
M
4
Testbed Specification

• BEE (Berkeley Emulation Engine)
• 600 GOP/s FPGA array previously developed at the
  BWRC
• To be used for data analysis and generation
• RF Front-end ?? BEE interface
• Thirty-two 1GHz fiber optical connections
• A/D and D/A
• 12-bit resolution for each of the sixteen DACs
  and ADCs
• Up to 64 MS/s sampling rate
• RF Front-end
• 20 MHz channel bandwidth
• 16 antennas
• Common local oscillator synthesizer
• Linear Power Amplifiers with output power 0 10
  dBm
• AGC with programmable gain of 0 36 dB

5
RF Front-end ?? BEE Interface

• Why we replaced the BEE SCSI interface with an
  optical interface
• Lower noise and good signal isolation
• Makes it possible to position RF front-end
  farther from BEE when required
• High transmission rate possible over optical
  connection without shielding
• Replaced SCSI connection with
• Xilinx Virtex II Pro
• Baseband data SERDES processing
• 1Gb/s serial rate
• Optical Transceivers
• Optical Riser Board
• BEE side SERDES processing

Optical Riser Cards
Peripheral Device
RF Front-end
Xilinx Chip
BEE
Optical Transceivers
6
Scalable RF Front-end


16
16
BEE
BEE
Fiber Optic Link
Fiber Optic Link


16
16
Up to 8 RF Modem Modules in each Chassis, for 16
antennas at each node. 2.40 2.485 GHz ISM Band
TDD. Optional FDMA in four sub-bands.
7
Single RF and Baseband Channel
RF Modem Module
JTAG
SBI TXON ANTSEL LNAGAIN
RSSI
PROM
AUX_ADC
ADC
Rx
LPF
Fiber Optic Xcvr Riser Card
Fiber Optic Xcvr
FPGA
BEE
DAC
LPF
Tx
SCSI Riser Card
AGC
AUX_DAC
SCSI
Ctrl
8
MCMA Baseband Modem and RF Transceiver Single RF
Modem Module
9
Local Oscillator and Digital Clock Distribution
14 RF Splitter
LNA
20 MHz VC-TCXO
Custom 2.4 GHz L.O. Distribution. Can be cascaded
for up to 16 L.O. outputs
National Synthesizer PCB used as 2.4 GHz Local
Oscillator
LVDS Dig-Clk from BEE
On-board Dig-Clk
MGT recovered clock
64 MHz LVDS Digital Clock Selection and
Distribution
10
Status Future Work

• MCMA Baseband board Designed, fabricated. Test
  in progress.
• RF Transceiver board (Intel) Three in house, 32
  to be fabricated.
• LO generation and distribution cards Top-level
  design complete, schematics next.
• Digital clock card and distribution
  Specification complete, design to commence.
• Power board In specification.
• Optical riser card Schematics complete, PCB
  layout next.
• Mechanical integration Modifying existing
  cellular base station chassis.
• Antenna array To be specified.