Abstract :
The efficiency of direct sequence (DS), BPSK modulated, code division multiple access (CDMA) systems is addressed, applying general concepts of the information theory. Under the hypothesis of a totally asynchronous system, which uses random signature sequences, it is shown that an ultimate efficiency of 2.16 bit/chip can be achieved. Moreover the performance is presented of systems that use convolutional codes, with constraint length 7 and rate up to 1/8.
Keywords :
code division multiple access; mobile communication systems; phase shift keying; BPSK modulated; asynchronous CDMA systems; code division multiple access; constraint length; convolutional codes; direct sequence; efficiency; information theory; random signature sequences; totally asynchronous system;
