Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 1 Space-Time Block Code Selection for more than two Transmit Antennas Mehmet E. Çelebi, Selami Şahin, Ümit Aygölü Istanbul Technical University Electronics & Communication Engineering Department Maslak, Istanbul 34469

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 2 Outline Channel Model Balanced Space-Time Codes Diversity and bit Error Probability Analysis Examples Simulation Results Conclusion

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 3 SPACETIMECODERSPACETIMECODER + ηtηt h1h1 h2h2 hnhn stst RECEİVER FEEDBACK Channel and Transceiver

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 4 Channel Model MISO system Frequency flat, quasi-static channel Fading coefficients and additive noise are independent complex Gaussian The receiver knows the fading coefficients perfectly The transmitter has partial knowledge of the channel

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 5 Receiver Observation equation: C is a balanced space-time code. Balanced codes are obtained by repeating, shuffling and negating the columns of the Alamouti matrix. Recall the Alamouti matrix: Example of 2x3 balanced code:

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 6 Linear Processing at the receiver: Approximate BER expression for M-PSK:

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 7 Another example of balanced codes for 4 antennas: The diversity terms after linear processing: Therefore, for fourth order diversity, choose

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Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 9

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Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 13 Conclusion Balanced codes with feedback are an efficient way to increase diversity Solely, with one more transmitter antenna and one bit feedback, one can increase the diversity by one Balanced codes are more resilient to feedback errors compared to antenna selection schemes The delay is also minimal, only two time slots are used

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 14 THANK YOU!

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Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page #

Istanbul Technical University, Electronics & Communication Engineering Department 2nd COST 289 Workshop, Special Topics on 4G Systems, July 7, 2005, Antalya, Turkey, Page 5 Receiver Observation equation: X is 2x2 Alamouti code, ie, W is an 2xn extender matrix whose each column contains a single ±1 Example: