A Simple Transmit Diversity Technique for Wireless Communications 指導老師 : 黃文傑 博士 學生 : 吳濟廷

OUTLINE Introduction Classical Maximal-Ratio Receiver Combining Scheme New Transmit Diversity Scheme  Two-branch transmit diversity with one receiver  Two-branch transmit diversity with M receiver Error Performance Simulations Conclusion

Introduction Next generation wireless system Multipath fading Tx power control Why don’t we use receive diversity ? Transmit diversity

Classical MRRC Scheme(1/2) Two-branch MRRC

Classical MRRC Scheme(2/2) Using the maximum likelihood decision rule for PSK signals (equal energy constellations) may be simplified to

New Transmit Diversity Scheme Two-Branch Transmit Diversity with One Receiver  Encoding and transmission sequence  Combining scheme  Maximum likelihood decision rule Two-Branch Transmit Diversity with M Receiver

Two-Branch Transmit Diversity with One Receiver(1/3) Two-Branch Transmit Diversity with One Receiver Encoding and transmission sequence

Two-Branch Transmit Diversity with One Receiver(2/3) The combining scheme: after substituting equations on previous page

Two-Branch Transmit Diversity with One Receiver(3/3) The maximum likelihood decision rule Resulting combined signals here are equivalent to that obtained from two-branch MRRC The new scheme The MRRC

Two-Branch Transmit Diversity with M Receiver(1/3) Two-Branch Transmit Diversity with Two Receiver Channels between the Tx and Rx antennas Notation for the two received antennas

Two-Branch Transmit Diversity with M Receiver(2/3) The combiner builds two signals substituting the appropriate equations equivalent to that of 4-branch MRRC

Two-Branch Transmit Diversity with M Receiver(3/3) Signals from 2 receive antennas are the simple addition of signals from each receive antennas

Error Performance Simulations BER performance comparison of MRRC and two-branch transmit diversity

Conclusion 2 Tx–1 Rx(New)=1 Tx–2 Rx(MRRC) => 2 Tx - M Rx = 1 Tx - 2M Rx Doesn’t need any feedback Computation complexity is similar to MRRC Performance is identical to MRRC (total power isn’t limited)

Reference [1]S.M. Almouti, ”A simple transmit diversity technique for wireless communications”, Journal of Selective Communications, Vol. 16, no. 8, pp , Oct. 1998