Multiple Antenna, SVD based Algorithm Implementation

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Multiple Antenna, SVD based Algorithm
Implementation

• Dejan Markovic, Ada Poon, Haiyun Tang
• Prof. Bob Brodersen
• BWRC Winter Retreat
• 8 January 2002

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MIMO Capacity Gain
MIMO
Rx diversity
1 Tx, 1 Rx antenna case
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Wireless Channel Characterization
Linear time-varying filter with impulse response
h(t)
Sum of discrete rays with different amplitude and
random phases
Narrowband scenario ? ltlt Tsymbol Central Limit
Theorem
R Rayleigh ? Unif 0, 2?
Complex 1-tap narrowband flat Rayleigh channel
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Time-varying Multi-path Channel
1kHz Doppler 4 multi-paths 16 carriers
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MIMO Channel Model
Tx
Rx
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Concept of SVD
BB-equivalent channel models
y H x z
1.
y U ? V x z
SVD
2.
x' V x y' U y z' U z
y' ? x' z'
Unitary X-form
3.
Need to know V at Tx and U,? at Rx
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System Perspective
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Model of SVD based Tx-Rx

• LMS based blind tracking of SVD components U,?,V
• U?,V updated every symbol period
• Periodic feedback every few hundred data symbols
• Additional blocks required at the Rx side for
  blind tracking

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Simulink Simulation Model
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Architecture V Matrix
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Architecture U? Matrix
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Tracking Performance
tracked
ideal
Optimal step size
Weak subchannel
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Implementation Tracking V Matrix
Tracking Algorithm for V
?i ? R1?1 x, vi ? C4?1 yi ? C1?1
Algorithm Implementation (MC/SSHAFT)
vi(n1) vi(n) ?i ( yi(n1) vi(n)
x(n1) ) x(n1)
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Implementation Tracking U? Matrix
Tracking Algorithm for U,?
Receive y(n1)
r y(n1)
for i14
wi(n1) wi(n) ?i (r r wi(n) ?i(n)
w(n))
?i ? R1?1 y, wi ? C4?1 ?i ? R1?1
?i (n1) wi(n1) wi(n1)
exit at i4
r r - (wi(n1) r) wi(n1) / ?i (n1)
C1?1
C4?1
end for
Algorithm Implementation (MC/SSHAFT)
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Hardware Parameters (0.25mm)
Module Compiler based estimates _at_ fCLK100MHz
Building Blocks
inputs
output
P mW
A mm2
D ns
N
1.
5.9
0.156
7.7
C4?1 , C4?1
C1?1
Cmult_Vd_V
8
2.
0.4
0.075
2.1
C1?1 , C1?1
C1?1
Csub_d
8
3.
5.6
0.158
6.9
C1?1 , C4?1
C4?1
Cmult_S_V
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4.
2.2
0.064
7.2
R1?1 , C4?1
C4?1
Cmult_RS_V
8
5.
1.2
0.027
2.0
C4?1 , C4?1
C4?1
Csum_V_V
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6.
20.1
0.459
12.3
C4?1 , R1?1
C4?1
Cdiv_V_RS
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Summary of the overall SVD hardware
characteristics
SVD
inputs
output
P mW
A mm2
D ns
N
64
1.74
8.2
R1?1 ,C4?1 , C4?1
C4?1
V_est
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R1?1 , C4?1
U?_est
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R4?4 , C4?1
8.2
210
5.54
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SVD Based OFDM System
(A. Klein 00)
need 48 SVD blocks!
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SSHAFT Synthesis of V Matrix

• 0.18mm process

90 dense
V(1)
0.47mm
0.47mm
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Overall OFDM System Parameters
Module Compiler, fCLK 20MHz
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Breakdown of SVD-OFDM Chip Area
0.25mm
SVD
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Porting to a New Technology
4x4 OFDM system is feasible