Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Backwards compatibility
`
`How to make a MIMO-OFDM
`system backwards compatible and
`coexistence with 11a/g at the link
`level.
`
`Jan Boer, Bas Driesen and Pieter-Paul Giesberts, Agere Systems
`
`Submission
`
`Slide 1
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000001
`
`
`
`doc.: IEEE 802.11-03/714r0
`
`Backwards compatibility
`
`How to make a MIMO-OFDM
`system backwards compatible and
`coexistence with 11a/g at the link
`level.
`
`Jan Boer, Bas Driesen and Pieter-Paul Giesberts, Agere Systems
`
`Submission
`
`Slide 1
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000001
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`The PAR
`
`• Some of the modes of operation defined in
`the HT amendment shall be backwards
`compatible and interoperable with 802.11a
`and/or 802.11g.
`
`Submission
`
`Slide 2
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000002
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Meaning for MIMO-OFDM
`
`– Any higher order MIMO-OFDM system (with n Rx
`antennas) can receive a signal from a lower order
`MIMO/SISO transmitter (< n Tx antennas, SISO = 11a
`or 11g)
`– Detection of preamble, interpretation of the header:
`• Determining the number of transmit antennas (number of data
`streams) and switch Rx accordingly
`– Any higher order MIMO-OFDM transmitter (n Tx
`antennas) can transmit a signal that a lower order
`MIMO/SISO receiver can receive
`– Switch back to (ultimately) 11a or 11g
`
`Submission
`
`Slide 3
`
`Jan Boer, Agere Systems
`
`* order of MIMO system is dependent on # Tx antennas
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000003
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Coexistence requirement
`
`• Any lower order system (with n Rx antennas) that cannot
`receive data of a transmitter (with more than n antennas)
`defers while this transmitter is sending, because it is
`capable to detect the start of this transmission and retrieve
`the length (duration) of this transmission.
`– Defer not on power only
`– Detection of the preamble and interpretation of the length field,
`– Using existing multirate capabilities of the current standard(s)
`
`Submission
`
`Slide 4
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000004
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Backward Compatible Preambles
`
`• 11a/g preamble structure must be maintained
`• Two examples are given of preamble structures
`that can be made backward compatible and
`coexistent:
`– Repetition preamble
`– Diagonally loaded preamble
`• 3rd way: use protection mechanisms as defined in
`11g
`
`Submission
`
`Slide 5
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000005
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`1. Repeating preamble
`
`ST
`
`GI LT1 LT2
`
`Signal Sign2
`
`TX1
`
`TX2
`
`TX3
`
`GI LT1 LT2
`
`GI LT1 LT2
`
`•
`
`802.11a Long Training Symbols (including Guard Interval) repeated
`on every transmit antenna, separated in time
`• Channel training length equal to n times length 802.11a training
`• Following is an example for 3 antenna MIMO Tx:
`
`Submission
`
`Slide 6
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000006
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`3x3 Mimo Rx vs 11a Rx training
`
`TX1
`
`ST
`
`GI LT1 LT2
`
`• 3x3 Mimo
`– Detects short training
`symbols
`– Channel estimation (3
`paths), etc
`
`• 11a
`– Detects short training
`symbols
`– Channel estimation
`
`Submission
`
`Slide 7
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000007
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`MIMO notification
`
`TX1
`
`ST
`
`GI LT1 LT2
`
`Signal
`
`•
`
`• The Reserved bit 4 in the signal field is used to signal a MIMO
`transmission (R=1?)
`11a-1999 standard says:
`Bit 4 shall be reserved for future use
`• The 802.11a standard does not prescribe the value (all other reserved bits shall
`be set to zero for 11a compliance)
`• This most probably means that R is ignored by a 11a/g implementation
`
`Submission
`
`Slide 8
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000008
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Rate and Length field
`
`TX1
`
`ST
`
`GI LT1 LT2
`
`Signal
`
`• Rate: as defined in 11a (6,9,12….54Mbit/s) per antenna
`• Length in Bytes as defined in 11a per antenna
`•
`Includes
`– Payload
`– Sign2 (see next)
`– Additional training symbols
`– Padding bits
`
`Submission
`
`Slide 9
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000009
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`3x3 Mimo Rx vs 11a Rx signal
`
`TX1
`
`ST
`
`GI LT1 LT2
`
`Signal
`
`• Mimo
`– Signal detection
`• Rate valid
`• Length valid
`– Knows duration
`– Mimo notification
`
`• 11a
`– Signal detection
`• Rate valid
`• Length valid
`– Knows duration
`– Ignores R4
`
`Submission
`
`Slide 10
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000010
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`3x3 Mimo Rx vs 11a Rx sign2
`
`TX1
`
`ST
`
`GI LT1 LT2
`
`Signal Sign2
`
`# Tx antennas
`
`Additional Mimo info
`
`• Mimo
`– Detects # Tx antennas
`– Additional Mimo info:
`• E.g. correction on #
`bytes per antenna
`
`• 11a
`– Tries to demodulate
`payload
`– Does not recognize
`service field
`– Starts to decrement
`lengthfield
`
`Submission
`
`Slide 11
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000011
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`3x3 Mimo Rx vs 11a Rx
`
`ST
`
`GI LT1 LT2
`
`Signal Sign2
`
`TX1
`
`TX2
`
`TX3
`
`GI LT1 LT2
`
`GI LT1 LT2
`
`• Mimo
`– Trains other paths
`– Starts demod Mimo
`signal
`
`• 11a
`– Decrements length
`– Defers during duration
`of mimo transmission
`(CCA busy)
`
`Submission
`
`Slide 12
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000012
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Repeating preamble
`Backwards compatibility and coexistence
`
`• Higher order mimo can switch back to lower order using
`less antennas and adapt the training accordingly
`• Lower order mimo can be received by higher order
`– Mimo notification + # of transmit antennas
`• Lower order defers based on length and rate interpretation
`
`Submission
`
`Slide 13
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000013
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`2. Diagonally loaded preamble
`
`TX1
`
`TX2
`
`TX3
`
`ST
`
`ST
`
`ST
`
`GI LT1 LT2
`
`Signal
`
`GI LT1 LT2
`
`Signal
`
`GI LT1 LT2
`
`Signal
`
`Tx1
`
`Tx2
`
`-28
`
`+3
`
`+6
`
`+27
`
`-32 -31 -30 -29
`
`-27
`
`-26 -25 -24 -23
`
`-22
`
`-21
`
`-20
`
`-6
`
`-5
`
`-4
`
`-3
`
`-2
`
`-1
`
`0
`
`+1 +2
`
`+4
`
`+5
`
`+22
`
`+23
`
`+24
`
`+25
`
`+26
`
`+28
`
`+29+30
`
`+31
`
`-27
`
`-24
`
`+22
`
`+28
`
`-6
`
`-5
`
`+5
`
`+6
`
`-32 -31 -30 -29
`
`-28
`
`-26 -25
`
`-23
`
`-22
`
`-21
`
`-20
`
`-4
`
`-3
`
`-2
`
`-1
`
`0
`
`+1 +2 +3 +4
`
`+23
`
`+24
`
`+25
`
`+26
`
`+27
`
`+29+30
`
`+31
`
`Tx3
`
`-23
`
`-20
`
`-5
`
`+2
`
`-32 -31 -30 -29
`
`-28
`
`-27
`
`-26 -25 -24
`
`-22
`
`-21
`
`-6
`
`-4
`
`-3
`
`-2
`
`-1
`
`0
`
`+1
`
`+3 +4
`
`+5 +6
`
`+22
`
`+23
`
`+24
`
`+25
`
`+26
`
`+27+28
`
`+29+30
`
`+31
`
`•
`
`802.11a Training sequence made orthogonal by diagonally loading subcarriers
`onto the transmit antennas
`• Training length equal to 802.11a training length
`
`Submission
`
`Slide 14
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000014
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Mimo channel estimation
`
`• Mimo:
`– Step 1: Adding the long training sequences to gain in SNR
`– Step 2: Transformation to frequency domain
`– Step 3:Demodulation of the combined long training sequences
`– Step 4: Interpolation of the subcarriers, to get the full channel estimate:
`
`• Problem of the edge subcarriers
`– Interpolation of the outer subcarriers cannot be done because these subcarriers have
`subcarriers only at one side
`– These subcarriers can only extrapolated
`– Extrapolation error is bigger than interpolation error
`• Solution
`– Adding extra subcarriers at the edges of the spectrum
`– These carriers can be used to transfer information
`
`Submission
`
`Slide 15
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000015
`
`
`
`Sept 2003
`doc.: IEEE 802.11-03/714r0
`11a/g channel estimation on diagonally loaded
`preamble
`
`• Combination of diagonally loaded sequences is 11a
`preamble, on which 11a can train.
`• Different Tx antennas will be reflected in the channel
`estimation.
`• Averaging techniques over carriers in frequency domain or reducing
`the channel impulse response length in the time domain might disrupt
`the estimation: possible compatibility issue.
`
`Submission
`
`Slide 16
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000016
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Mimo notification, Length, Rate
`
`TX1
`
`TX2
`
`TX3
`
`ST
`
`ST
`
`ST
`
`GI LT1 LT2
`
`Signal
`
`GI LT1 LT2
`
`Signal
`
`GI LT1 LT2
`
`Signal
`
`• Use R4 in signal field for MIMO notification
`• Rate as defined in 11a per antenna
`• Length in Bytes per antenna
`• Extra subcarriers at edge of spectrum can signal the number of transmit
`antennas
`
`Submission
`
`Slide 17
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000017
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Mimo vs 11a/g reception
`
`TX1
`
`TX2
`
`TX3
`
`ST
`
`ST
`
`ST
`
`• Mimo
`– Detect short training symbols
`– Channel estimation
`– Signal detection, rate, length
`– # antennas in edge subcarriers
`– Decode mimo signal
`
`GI LT1 LT2
`
`Signal
`
`GI LT1 LT2
`
`Signal
`
`Signal
`
`GI LT1 LT2
`• 11a/g
`– Detect short training symbols
`– Channel estimation
`– Signal detection, valid rate, valid
`length
`– Tries to demodulate, no service
`field
`– Decrements length
`– Defers during duration of mimo
`transmission (CCA busy)
`
`Submission
`
`Slide 18
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000018
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Diagonally loaded preamble
`Backwards compatibility and coexistence
`
`• Higher order mimo can switch back to lower order using
`less antennas and adapt the training accordingly
`• Lower order mimo can be received by higher order
`– Mimo notification + # of transmit antennas
`• Lower order defers based on length and rate interpretation
`
`Submission
`
`Slide 19
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000019
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`3. Protection Mechanism
`
`• As in 11g:
`– Precede Mimo transmission with 11a or 11g
`(RTS/)CTS to reserve medium
`• Advantage: Mimo preamble can be
`dedicated
`• Disadvantage: overhead
`
`Submission
`
`Slide 20
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000020
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Preamble and throughput
`
`• Longer preamble effects throughput negatively
`•
`If longer preambles are necessary (performance,
`backwards compatibility,…) the effect on throughput
`should be clear.
`• Next slides show examples of preamble overhead
`compared to other overheads for 54Mbit/s and 162Mbit/s
`
`Submission
`
`Slide 21
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000021
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Throughput overview
`
`@1500 bytes frames
`
`Efficiency & throughput
`
`Regular
`
`3 frame burst
`
`3 frame aggregation
`
`54 Mbit/s
`
`162 Mbit/s
`(20μs preamble)
`
`162 Mbit/s
`(40μs preamble)
`
`66% = 36 Mbit/s
`
`69% = 38 Mbit/s
`
`84% = 45 Mbit/s
`
`40% = 67 Mbit/s
`
`45% = 75 Mbit/s
`
`66% = 107 Mbit/s
`
`35 % = 59 Mbit/s
`
`39% = 65 Mbit/s
`
`62% = 101 Mbit/s
`
`Effect of preamblelength is not neglegable but for the boost of throughput
`other techniques must be applied such as frame bursting or aggregation
`
`Submission
`
`Slide 22
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000022
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`54 Mbit/s
`
`Relative overhead per category (no RTS/CTS, no bursting)
`
`Relative overhead per category (no RTS/CTS, 3 frame burst)
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`Relative overhead per category
`(no RTS/CTS, 3 MAC frames in one PHY frame, one ACK)
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`100%
`
`80%
`
`60%
`
`40%
`
`20%
`
`0%
`
`100%
`90%
`
`80%
`70%
`
`60%
`50%
`40%
`
`30%
`20%
`
`10%
`0%
`
`Percentage lost throughput
`
`Percentage lost throughput
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`100%
`
`90%
`
`80%
`
`70%
`
`60%
`
`50%
`
`40%
`
`30%
`
`20%
`
`10%
`
`0%
`
`Percentage lost throughput
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`Datarate = 54Mbit/s, Ack rate = 24 Mbit/s
`
`Submission
`
`Slide 23
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000023
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`162 Mbit/s
`
`(20 µs preamble+header, diagonally loaded)
`
`Relative overhead per category (no RTS/CTS, no bursting)
`
`Relative overhead per category (no RTS/CTS, 3 frame burst)
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`Relative overhead per category
`(no RTS/CTS, 3 MAC frames in one PHY frame, one ACK)
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`100%
`
`90%
`
`80%
`
`70%
`
`60%
`
`50%
`
`40%
`
`30%
`
`20%
`
`10%
`
`0%
`
`100%
`90%
`
`80%
`70%
`
`60%
`50%
`40%
`
`30%
`20%
`
`10%
`0%
`
`Percentage lost throughput
`
`Percentage lost throughput
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`100%
`
`90%
`
`80%
`
`70%
`
`60%
`
`50%
`
`40%
`
`30%
`
`20%
`
`10%
`
`0%
`
`Percentage lost throughput
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`Datarate = 162 Mbit/s,
`Ack rate = 54 Mbit/s (both frames on MIMO speed)
`
`Submission
`
`Slide 24
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000024
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`162 Mbit/s
`
`(40 µs preamble+header, repeating)
`
`Relative overhead per category
`(no RTS/CTS, 3 MAC frames in one PHY frame, one ACK, long preamble)
`
`Relative overhead per category
`(no RTS/CTS, 3 MAC frames in one PHY frame, one ACK, long preamble)
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`Relative overhead per category
`(no RTS/CTS, 3 MAC frames in one PHY frame, one ACK, long preamble)
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`100%
`90%
`
`80%
`70%
`60%
`50%
`40%
`
`30%
`20%
`10%
`0%
`
`100%
`90%
`
`80%
`70%
`60%
`50%
`40%
`
`30%
`20%
`10%
`0%
`
`Percentage lost throughput
`
`Percentage lost throughput
`
`MAC Ack
`PHY Ack
`SIFS
`Data
`MAC Data
`PHY Data
`DIFS
`contention
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`100%
`90%
`
`80%
`70%
`60%
`50%
`40%
`
`30%
`20%
`10%
`0%
`
`Percentage lost throughput
`
`Datarate = 162 Mbit/s,
`Ack rate = 24 Mbit/s (Ack on regular .11a speed)
`
`Submission
`
`Slide 25
`
`Jan Boer, Agere Systems
`
`64
`
`500
`
`1500
`1000
`Packetsize (byte)
`
`2000
`
`2312
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000025
`
`
`
`Sept 2003
`
`doc.: IEEE 802.11-03/714r0
`
`Conclusion
`
`• A MIMO-OFDM system can be made (fairly simple)
`backwards compatible and coexistent with 11a/g on the
`link level.
`– Preamble based on 11a/g preamble structure
`– Repeated preamble
`– Diagonally loaded preamble
`– 11g protection mechanisms
`• Criteria for decision:
`– Throughput overhead
`– Performance
`– Complexity
`
`Submission
`
`Slide 26
`
`Jan Boer, Agere Systems
`
`HUAWEI EXHIBIT 1007
`HUAWEI VS. SPH
`
`000026
`
`
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