Diversity with distributed decisions combining for direct-sequenceCDMA in a shadowed Rician-fading land-mobile satellite channel

摘要

The performance of two diversity schemes with distributedndecisions combining is analyzed and compared with that of the selectionnand maximal ratio-combining schemes for binary-phase shift keying (BPSK)ndirect-sequence code-division multiple access (DS-CDMA) in a shadowednRician-fading land-mobile satellite channel. In the first scheme ofndistributed decisions combining, the combiner collects only the binarynbranch decisions to make the data decision. In the second scheme, thencombiner makes the data decision using the branch decisions and thenchannel states. Both symmetrical and asymmetrical diversity branches arenconsidered. Based on optimal likelihood ratio testing, a new datandecision rule is devised for the detection of the spread-spectrumnsignals in the DS-CDMA system. Upper bounds are employed for thenperformance evaluation of the diversity combining schemes when the bitnerror probability is difficult to compute. Numerical results arenpresented for the satellite channel under light, average, and heavynshadowing