Title :
Blind adaptive multiuser detection for DS/SSMA communications with generalized random spreading
Author :
Cho, Joon Ho ; Lehnert, James S.
Author_Institution :
Sch. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA
fDate :
6/1/2001 12:00:00 AM
Abstract :
A new spreading scheme and an accompanying blind adaptive receiver structure are proposed for direct-sequence spread-spectrum multiple-access communications in a slowly-varying, frequency-selective fading channel. Each user´s spreading sequence is given by the Kronecker product of a long-period pseudonoise (PN) sequence, which is accurately modeled by a random sequence, and a short-length deterministic signature code. This spreading scheme bridges the gap between pure PN spreading and pure short-code spreading schemes. It is shown that with this spreading scheme, the channel response to the desired signal component is easily estimated without relying on the spectral decomposition of the signal correlation matrix. With the estimate of the channel response, the receiver suppresses interference based on the maximum signal-to-interference ratio criterion. The blind adaptive receiver requires only coarse timing information and a priori knowledge of the desired user´s PN sequence for adaptation. Numerical results show that the adaptive receiver significantly suppresses interference by successfully estimating the channel response and the interference statistics with a low computational complexity. An extension to spatio-temporal processing using an array antenna is also discussed
Keywords :
adaptive signal detection; array signal processing; code division multiple access; computational complexity; fading channels; interference suppression; multiuser channels; radio receivers; radiofrequency interference; random processes; space-time adaptive processing; spread spectrum communication; DS/SSMA communications; Kronecker product; PN spreading; array antenna; blind adaptive multiuser detection; blind adaptive receiver; channel response; coarse timing information; direct-sequence spread-spectrum multiple-access; frequency-selective fading channel; generalized random spreading; interference statistics; interference suppression; long-period pseudonoise sequence; low computational complexity; maximum signal-to-interference ratio; random sequence; short-code spreading; short-length deterministic signature code; signal component; signal correlation matrix; slowly-varying fading channel; spatio-temporal processing; spectral decomposition; spreading scheme; spreading sequence; Bridges; Computational complexity; Frequency-selective fading channels; Interference suppression; Matrix decomposition; Multiuser detection; Random sequences; Spread spectrum communication; Statistics; Timing;
Journal_Title :
Communications, IEEE Transactions on