Error Control Coding, Second Edition
Error Control Coding, Second Edition
Coordinated Multiuser Communications
Coordinated Multiuser Communications
Coding for the multiple-access adder channel
General Theory of Information Transfer and Combinatorics
Coding scheme for synchronous-CDMA systems
IEEE Transactions on Information Theory
A new approach to the design of codes for synchronous-CDMA systems
IEEE Transactions on Information Theory
| Hi-index | 754.84 |
Novel coding schemes for noiseless and noisy asynchronous code division multiple access (A-CDMA) systems are presented in this paper. The schemes use Wu-Chang spreading code, block interleaver, and synchronizable channel codes to support A-CDMA communications with random delays. For the noiseless case, each active user generates one of M messages, M = ⌊(2T-D- 1)/(D + 1)⌋, and a (T - D)-stage MLSR encoder encodes the message into a codeword of length T. Given a maximum random delay of D chips, the receiver can decode messages of all active users without ambiguity. For the noisy case, extended Bose-Caldwell cyclic codes are used to encode messages. The extended cyclic codes provide error correction and delay recovery effectively. By using a BCH code oflength n as the cyclic code, the extended code can correct up to τ ≤ ⌊n/4⌋ errors and recover a maximum random delay of n - 1 chips.