Title :
Concatenated coded spreading with coherent demodulation for DS-CDMA
Author :
Frey, Thomas ; Schramm, Peter
Author_Institution :
Dept. of Inf. Technol., Ulm Univ., Germany
Abstract :
In DS-CDMA systems, spreading may be viewed as inner coding and user-specific scrambling. In practice, spreading is combined with an outer convolutional code, which leads to so-called concatenated coded spreading (CCS). The standard approach is to use repetition codes. In the IS-95 uplink, a (64,6,32) orthogonal code is defined, which can be interpreted as 64-ary orthogonal modulation. In this paper, a CCS scheme with power efficiency superior to the IS-95 uplink is proposed. The use of decision-directed coherent demodulation for both schemes is discussed, and it will be shown that the coding gain of the improved CCS requires a modified channel estimation scheme
Keywords :
cellular radio; code division multiple access; concatenated codes; convolutional codes; demodulation; pseudonoise codes; spread spectrum communication; (64,6,32) orthogonal code; 64-ary orthogonal modulation; DS-CDMA; IS-95; channel estimation scheme; coding gain; coherent demodulation; concatenated coded spreading; decision-directed coherent demodulation; inner coding; repetition codes; user-specific scrambling; AWGN channels; Binary phase shift keying; Carbon capture and storage; Channel estimation; Concatenated codes; Convolutional codes; Demodulation; Information technology; Modulation coding; Multiaccess communication;
Conference_Titel :
Vehicular Technology Conference, 1998. VTC 98. 48th IEEE
Conference_Location :
Ottawa, Ont.
Print_ISBN :
0-7803-4320-4
DOI :
10.1109/VETEC.1998.686088
