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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 1 ¼ Giga-Bit/s WLAN Gerhard Fettweis Gunnar Nitsche Systemonic AG

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 2 Historically Based Projection 802.11: 2Mb/s 802.11b: 11Mb/s 5x 802.11a: 54Mb/s 5x 802.11new: ¼ Gb/s 5x 100Mb/s

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 3 Increasing Data Rate by Doubling the Bandwidth By doubling bandwidth data rate can be increased by a factor 108/48=2.25

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 4 MIMO Systems Scalar system capacity: Ignore fading statistics, account only for antenna gain Idealized vector case: Assume signals from each transmitter can be separately detected without penalty Vector encode: DEMUX data into QAM symbols Estimate and decode a 1 a 2 T x Data R x P/2 watts Total transmit power P Bandwidth = 1/T=W (All transmitters operate co-channel) Each R x SNR= S/2 Vector system Estimate and decode T x Data R x P watts Total transmit power P Each R x SNR= S Traditional scalar system

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 5 Use of Higher Order Modulations To attain bandwidth efficiencies it is necessary to couple coding with symbols from higher order modulation If higher modulation orders are used the phase difference between the constellation points gets smaller Phase noise introduced would cause an error in interpreting the constellation point Degradation in the signal to noise ratio occurs By allowing the use of 256 QAM data rate is increased by a factor 8/6

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 6 Using Transmit Diversity to Increase Diversity Employ coding techniques appropriate to multiple transmit antennas Space Time Codes introduce temporal and spatial correlation into signals transmitted from different antennas They provide diversity at the receiver and coding gain over an uncoded system without sacrificing bandwidth Obtained diversity can compensate for the loss caused by phase noise

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 7 Increasing Capacity Using Multiple Antennas and STC (Space Time Coding) The effective transmission rate is increased roughly in proportion to a number of min(#T x antennas, #R x antennas)

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doc.: IEEE 802.11-02/320r0 Submission May 2002 Gerhard Fettweis, Systemonic AGSlide 8 Resulting Data Rate Increased bandwidth factor: 2.25 Vector (layered) system factor: <2 (take 1.5) Higher order modulation factor: 8/6 (by using 256-QAM) Using these parameters ¼ Gb/s rate is achievable

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