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—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 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)
— 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)
In this paper, a new reliable cooperative MAC protocol, which can enhance the system throughput under bad wireless channel environments, is proposed, and the protocol's performance is evaluated with a computer simulation. The system throughput and average delay, except queuing delay, are used as performance metrics. The numerical results show that the(More)
In this paper, we present the performance evaluation of the reliable cooperative media access control (RCO-MAC) protocol, which has been proposed in [1] by us in order to enhance system throughput in bad wireless channel environments. The performance of this protocol is evaluated with computer simulation as well as mathematical analysis in thispaper. The(More)