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We propose a new selection diversity scheme, called -selection diversity, that selects the branch providing the largest magnitude of log-likelihood ratio (LLR). The LLR for BPSK signals in fading channels is found to be proportional to the product of the fading amplitude and the matched filter output after phase compensation. The proposed -selection(More)
We propose a new detection ordering based on the log-likelihood ratio (LLR) in the iterative nulling and cancellation process of vertical Bell Laboratories layered space–time (V-BLAST) decoding. The motivation for using the LLR is that it provides the reliability information on the maximum a posteriori probability decision. As a result, the error(More)
We consider combined rate and power adaptations in direct-sequence code-division multiple-access communications, where the transmission power and the data rate are adapted relative to channel variations. We discuss the power gain that the combined adaptations provide over power adaptation. Then, we consider an integrated voice and data transmission system(More)
We investigate the average information rates attained by adapting the transmit power and the information rate relative to channel variations in code division multiple access communication systems. Our results show that the rate adaptation provides a higher average information rate than the power adaptation for a given average transmit power, and the rate(More)
We propose the multicarrier on–off keying (MC-OOK) as a bandwidth-efficient modulation method for frequency-hopped multiple-access (FHMA) communications. The motivation for using MC-OOK is that a more bandwidth-efficient modulation scheme allows a larger number of frequency slots, and thus provides a higher immunity against multiple-access interference in(More)
We propose a new detection ordering for the V-BLAST. The main idea is to detect and cancel sub-streams in order of the magnitude of log-likelihood ratio (LLR), i.e. the symbol with the largest magnitude of LLR is detected first. The motivation is that the reliability of data decision increases with increasing magnitude of LLR. As a result, the error(More)
We analyze the performance of truncated power control in a code-division multiple-access (CDMA) communication system. This power control scheme compensates for propagation gain above a certain cutoff fade depth: below the cutoff level, data transmission is suspended. We assume a channel with fast Rayleigh fading and slow lognormal shadowing plus path loss,(More)