`
`doc.: IEEE 802.11-03/0513r0
`
`Optimal Combining of STBC and
`Spatial Multiplexing for MIMO-OFDM
`
`Taehyun Jeon, Heejung Yu, and Sok-kyu Lee
`Wireless LAN Modem Research Team, ETRI
`Jihoon Choi and Yong H. Lee
`KAIST
`
`Submission
`
`Slide 1
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000001
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Contents
`
`• Spatial Multiplexing for MIMO Systems
`– Detection Methods
`• Transmit Diversity for MIMO Systems
`– Transmit Diversity using STBC
`• Combining of STBC and Spatial Multiplexing
`• Simulation results
`• Conclusion
`
`Submission
`
`Slide 2
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000002
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Spatial Multiplexing for MIMO Systems
`
`Tx 1
`
`)(1 nx
`
`Rx 1
`
`)(1 ny
`
`Spatial
`Demultiplexing
`
`Tx 2
`
`Tx N
`
`)(2 nx
`
`
`
`)(nxT
`
`Spatial
`Multiplexing
`
`Rx 2
`
`)(2 ny
`
`
`
`Rx M
`
`)(nyR
`
`• Transmit independent parallel data streams through
`multiple antennas
`• Increase the data rate T times faster than SISO
`
`Submission
`
`Slide 3
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000003
`
`
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`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Detection of Spatial Multiplexed Signal
`
`H
`
`• Maximum Likelihood (ML) Detection
`
`
` )(ˆ nx
`
` )({min y n
`
`Hx
`
`
`Hx
` )({ ny
`
`)}(n
`
`)}(n
`
`
`
`x
`ni
`)(
`)( nix
`
` all constellat setion possible
`
`
`
`
`– Complexity: ~ LToperation required (L: constellation size)
`• Linear Detection
`
`
` )(ˆ nx
`
` ) yHHH
`{( decision
`
`H
`H
`1
`
`
`
`
` )(ˆ nx
`HH
`I
`{( decision
`
`H
`2
`
`
`
`• V-BLAST Detection
`– Nulling & Canceling : Successive detection of data streams
`(layer by layer)
`– Complexity: ~ O(29T3/3)
`
` :)}(n
`
` Forcing Zero
`
`yH
`
` :)}(n
` MMSE
`)
`H
`1
`
`
`
`
`N
`
`Submission
`
`Slide 4
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000004
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Spatial Multiplexing for MIMO-OFDM
`
`• OFDM sub-divides the wideband channel into multiple flat fading
`subcarriers and can be implemented simpler and more efficient
`demodulation processing (IFFT/FFT and FEQ) over single carrier
`systems
`• MIMO-OFDM with T=R=2: Complexity ~ O(29NT3/3) when V-
`BLAST detection used
`
`)0(1x
`
`
`Nx
`(1
`
`)1
`
`)0(2x
`
`
`Nx
`(2
`
`)1
`
`IFFT
`
`P/S
`
`
`
`IFFT
`
`P/S
`
`
`
`11h
`12h
`
`22h
`
`21h
`
`FFT
`
`P/S
`
`
`
`P/S
`
`
`
`FFT
`
`)0(1y
`
`Ny
`(1
`
`)1
`
`)0(2y
`
`Ny
`(2
`
`)1
`
`
`
`
`
`Submission
`
`Slide 5
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000005
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Transmit Diversity for MIMO Systems
`• Techniques compatible to IEEE 802.11a
`– Delay Diversity and Random Phase Diversity
`– Simple to implement but not significant performance gain
`with number of antenna increase
`• Space-Time Block Coding (STBC)
`– Simpler implementation than Trellis Coding
`– Alamouti code provides diversity order 2 with T=2 and R=1
`
`
`
`1 rr 2
`
`
`
`Space-time
`block
`decoding
`
`ˆ
`x
`1
`
`
`
`ˆ
`x
`
`2
`
`1h
`
`2h
`
`*2
`
`
`
`- x
`
`x
`1
`
`2 x
`
`*1
`
`x
`
`
`
`1 xx
`
`2
`
`Space-time
`block coding
`
`Submission
`
`Slide 6
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000006
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`STBC for MIMO-OFDM
`x
`- x
`1
`
`*2
`
`P/S
`
`P/S
`
`
`
`
`
`IFFT
`
`
`
`IFFT
`
`
`2 x
`
`*1
`
`x
`
`
`
`1 xx
`
`2
`
`)(nx
`
`S/P
`
`
`
`STBC
`
`
`
`[
`
`
`
`[
`
`x
`1
`x
`
`2
`
`),0(
`
`,
`
`
`),0(
`
`
`x
`x
`
`1
`
`2
`
`:N
`
`
`
` of ssubcarrierNumber
`
`
`
`
`
`Submission
`
`Slide 7
`
`Taehyun Jeon, ETRI
`
`)]1
`T
`
`Nx (
`
`
`1
`
`2
`
`,
`
`Nx (
`
`
`
`)]1
`T
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000007
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`N x N MIMO Channels
`• In terms of Spatial Multiplexing
`– Data rate increases as number of
`antenna increases
`– No significant diversity advantages
`
`1x
`
`2x
`
`Nx
`
`• In terms of Diversity
`– Maximum diversity gain can be
`achieved
`– Higher order modulation needed to
`increase the data rate SNR loss
`
`x
`
`1,1h
`
`2,2h
`
`
`NNh ,
`
`1,1h
`
`
`Nh ,1
`1,2h
`
`
`NNh ,
`
`1y
`
`2y
`
`Ny
`
`1,1y
`
`Ny ,1
`1,2y
`
`NNy ,
`
`• For best performance for a target data rate, optimal
`combining of above should be considered
`
`Submission
`
`Slide 8
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000008
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Combining of 2-layer Spatial Multiplexing
`and Alamouti Code
`ny
`
`nx
`
`S/P
`
`na
`
`nb
`
`STBC
`
`STBC
`
`IFFT
`
`P/S
`
`S/P
`
`FFT
`
`IFFT
`
`P/S
`
`IFFT
`
`P/S
`
`STBC Based
`V-BLAST
`Detection
`
`^
`nx
`
`P/S
`
`
`
`IFFT
`
`P/S
`
`S/P
`
`FFT
`
`Tx 1
`
`a2n
`
`t=2n
`
`t=2n+1
`
`-a*
`2n+1
`
`Tx 3
`
`b2n
`
`-b*
`2n+1
`
`Tx 4
`
`b2n+1
`
`b*
`2n
`
`Tx 2
`
`a2n+1
`
`-a*
`2n
`
`Slide 9
`
`Taehyun Jeon, ETRI
`
`Submission
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000009
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Simulation Parameters
`• IEEE 802.11a PHY Based Frame
`• Number of Subcarriers (data subcarriers): 64 (48)
`• Number of Cyclic Prefix: 16
`• Sampling Rate: 20MHz
`• Modulation: QPSK, 16QAM, 256QAM
`• Number of Tx and Rx Antenna: 2, 4
`• Channel Coding: None
`• Channel Model: Independent MIMO Channel
`– ETSI/BRAN Channel Model B (RMS Delay Spread = 100ns)
`– Quasi Static Channel (no change within one frame)
`
`Submission
`
`Slide 10
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000010
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Simulation Results (T=2,R=2)
`
`Mode 1:
`
`48Mbps
`
`QPSK
`
`24Mbaud
`
`S/P
`
`12Mbaud
`
`Mode 2:
`
`48Mbps
`
`16QAM
`
`12Mbaud
`
`12Mbaud
`2x2 STBC
`
`Mode 1: QPSK, 2 layers
`Mode 2: 16QAM, 1 layer, 2x2 STBC
`
`• Mode 2 (16QAM and Alamouti) performs
`better than Mode 1 (QPSK and 2-layered)
`Diversity gain of order 4 in Mode 2
`overcomes the ~4dB degradation of
`higher order modulation
`
`•
`
`5
`
`20
`15
`10
`Eb/No per Rx antenna (dB)
`
`25
`
`30
`
`10-1
`
`10-2
`
`10-3
`
`10-4
`
`10-5
`
`10-6
`0
`
`BER
`
`Submission
`
`Slide 11
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000011
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Simulation Results (T=4,R=2)
`
`Mode 1:
`
`48Mbps
`
`QPSK
`
`24Mbaud
`
`S/P
`
`12Mbaud
`
`12Mbaud
`
`2x2 STBC
`
`2x2 STBC
`
`12Mbaud
`
`Mode 2:
`
`48Mbps
`
`16QAM
`
`12Mbaud
`
`4x4 STBC
`
`Mode 1: QPSK, 2 layers, 2x2 STBC
`Mode 2: 16QAM, 1 layer, 4x4 STBC
`
`• Mode 2 (16QAM and 4x4 STBC) performs
`better than Mode 1 (QPSK and 2-layered
`Alamouti) beyond Eb/No=8dB
`Diversity order 4 over 3
`
`•
`
`5
`
`10
`Eb/No per Rx antenna (dB)
`
`15
`
`20
`
`10-1
`
`10-2
`
`10-3
`
`10-4
`
`10-5
`
`10-6
`0
`
`BER
`
`Submission
`
`Slide 12
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000012
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Simulation Results (T=4,R=4)
`
`12Mbaud
`
`Mode 1:
`
`96Mbps
`
`QPSK
`
`48Mbaud
`
`S/P
`
`Mode 2:
`
`96Mbps
`
`24Mbaud
`
`16QAM
`
`S/P
`
`12Mbaud
`
`12Mbaud
`
`2x2 STBC
`
`2x2 STBC
`
`12Mbaud
`
`Mode 3:
`
`96Mbps
`
`12Mbaud
`
`256QAM
`
`4x4 STBC
`
`Three different combinations are tested
`•
`• Mode 2 (16QAM and 2-layered Alamouti)
`performs best beyond 5dB
`• Mode 1 (QPSK and 4-layered) : Average
`diversity gain ~2.5
`• Mode 2 and Mode 3 : diversity gain about
`the same but 256QAM performs ~8dB
`worse than 16QAM
`
`Mode 1: QPSK, 4 layers
`Mode 2: 16QAM, 2 layers, 2x2 STBC
`Mode 3: 256QAM, 1 layer, 4x4 STBC
`
`5
`
`10
`Eb/No per Rx antenna (dB)
`
`15
`
`20
`
`10-1
`
`10-2
`
`10-3
`
`10-4
`
`10-5
`
`10-6
`0
`
`BER
`
`Submission
`
`Slide 13
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000013
`
`
`
`July 2003
`
`doc.: IEEE 802.11-03/0513r0
`
`Conclusions
`
`• Optimal MIMO-OFDM system should be selected by
`trading-off the spatial multiplexing and diversity gain
`for a given antenna arrangement
`• Candidate combined systems of STBC and spatial
`multiplexing proposed and their performances
`compared for extended IEEE 802.11a systems
`• Performance evaluations with realistic MIMO channel
`model for further work items
`
`Submission
`
`Slide 14
`
`Taehyun Jeon, ETRI
`
`HUAWEI EXHIBIT 1006
`HUAWEI VS. SPH
`
`000014
`
`