Title :
Variable rate QAM for mobile radio
Author :
Webb, W.T. ; Steele, R.
Author_Institution :
Smith Syst. Eng. Ltd., Guildford, UK
fDate :
7/1/1995 12:00:00 AM
Abstract :
Quadrature amplitude modulation (QAM) schemes which vary the number of modulation levels in accordance with the mobile radio fading channel variations are investigated. Important parameters considered are the fading rate and the block size used. We describe how the adaptive QAM modems can be employed and consider their use in a DECT-like TDD packet structure. System performance in the presence of cochannel interference is also considered. Simulations show that the variable rate system has about 5 dB improvement in channel SNR over a fixed 16-level QAM system for BER´s between 10-2 and 10-5 and channel SNR´s between 25 and 40 dB
Keywords :
Rayleigh channels; cochannel interference; cordless telephone systems; data communication; digital radio; fading; land mobile radio; modems; quadrature amplitude modulation; radiofrequency interference; BER; DECT-like TDD packet structure; adaptive QAM modems; block size; channel SNR; cochannel interference; fading channel variations; fading rate; mobile radio; modulation levels; quadrature amplitude modulation; system performance; variable rate QAM; variable rate system; Amplitude modulation; Bit error rate; Fading; Interchannel interference; Land mobile radio; Modems; Quadrature amplitude modulation; Radio transmitters; Switches; Throughput;
Journal_Title :
Communications, IEEE Transactions on
