Transmit power control with an accurate SNR measurement in M-ary/SS scheme for DS/CDMA systems

This paper proposes an accurate signal to interference plus noise power ratio (SINR) measurement technique to correctly proceed transmit power control (TPC) in M-sequence-based M-ary/spreading spectrum (M-ary/SS) scheme to realize high bit rate transmission for M-ary/SS/code division multiple access (M-ary/SS/CDMA) systems. Because the accuracy of TPC depends largely on the accuracy of SINR measurement, to sufficiently proceed TPC, the proposed scheme measures power ratio of the correlation peak to the other correlations in the correlator for M-ary/SS employing a correlation peak detector that regenerates the spreading sequence from the Viterbi decoded output data. Computer simulation confirms that the M-ary/SS scheme with regenerating spreading sequence can achieve much better bit error rate (BER) performance with decrease of peak transmit power of 5 dB in comparison with the conventional direct sequence/spread spectrum (DS/SS) scheme under ITU-Vehicular B model