Title :
Noncoherent detection in asynchronous multiuser channels
Author :
Varanasi, Mahesh K.
Author_Institution :
Dept. of Electr. & Comput. Eng., Colorado Univ., Boulder, CO, USA
fDate :
1/1/1993 12:00:00 AM
Abstract :
The noncoherent demodulation of multiple differentially phase-shift-keyed signals transmitted simultaneously over an asynchronous code-division multiple-access (CDMA) channel with white Gaussian background noise is considered. A class of bilinear detectors is defined with the objective of obtaining the optimal bilinear detector. The optimality criterion considered is near-far resistance that denotes worst-case asymptotic efficiency over the signal energies and phases which are unknown at the receiver. The optimal bilinear detector is therefore obtained by solving a minimax optimization problem. In the finite packet length case, this detector is shown to be a time-varying multiinput multioutput linear decorrelating filter followed by differential decision logic. In the limit as packet lengths go to infinity, the time-varying decorrelating detector is replaced by a time-invariant multiinput multioutput decorrelating filter. Several properties of the optimally near-far resistant detector are established
Keywords :
code division multiple access; demodulation; filtering and prediction theory; minimax techniques; phase shift keying; signal detection; telecommunication channels; white noise; CDMA; DPSK; asynchronous multiuser channels; code-division multiple-access; differential decision logic; finite packet length; minimax optimization problem; multiple differentially phase-shift-keyed signals; near-far resistance; noncoherent demodulation; noncoherent detection; optimal bilinear detector; time-invariant multiinput multioutput decorrelating filter; time-varying multiinput multioutput linear decorrelating filter; white Gaussian background noise; worst-case asymptotic efficiency; Background noise; Decorrelation; Demodulation; Detectors; H infinity control; Logic; Minimax techniques; Multiaccess communication; Multiuser channels; Nonlinear filters;
Journal_Title :
Information Theory, IEEE Transactions on