Wireless Communications: Principles and Practice
Wireless Communications: Principles and Practice
Microwave Mobile Communications
Microwave Mobile Communications
Array processing for wireless communications
SSAP '96 Proceedings of the 8th IEEE Signal Processing Workshop on Statistical Signal and Array Processing (SSAP '96)
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This paper describes low-complexity diversity receiver techniques suitable forhandsets and other wireless mobile applications. The techniques areillustrated using two branches of diversity feeding aparameter-combining RF circuit at the front-end, followed by asingle digital receiver chain. A baseband processing algorithm isused to adjust the front-end combining parameters, allowing the receiver toadaptively choose among three different diversity techniques. The method aspresented is primarily targeted for indoor environments where handset movementis slow and delay spread is small. We present algorithms for efficientco-phasing and equal-gain combining as well as a novel cochannelinterference-reduction algorithm. These are implemented in a system simulationat 900 MHz which conforms to the PACS standard. Link performance for selectiondiversity (SD), equal-gain combining (EGC), and interference-reductioncombining (IRC) is presented. The algorithm's performance is compared withoptimal combining parameters, and its performance as a function of Dopplerfrequency is enhanced. The results show that EGC and IRC yield asignal-to-noise improvement of 1 dB and a signal-to-interference improvementof 4 to 5.5 dB respectively, compared with SD. The receiver also lowers theirreducible word error rate due to multipath delay spread for Doppler shiftsof 6 Hz and below. Finally, algorithm behavior is characterized and discussed.