Study On Blind Adaptive Multiuser Detection Technoligy

In this paper, a new Interference-space-Based blind adaptive MMSE linear detector and the corresponding tracking algorithm based interference correlation matrix is proposed for MAI in CDMA wireless celluar communication system. Analysis and simulation illustrate that the proposed blind multiuser detector has lower computational complexity, faster convergence and stronger robust with respect to imprecise knowledge of the received signature waveform of user of interest.With the increase of active user numbers in CDMA channels, single user detector cannot effectively suppress MAI. Traditional multiuser detector make good use of all signals which resuilt in multiple access interference so that it provides optimum MAI resistance. (1) Nevertheless, it assumes that the receiver can acquire the signature waveform and timing of desired user and the interfering users ; (2) It has no ability to suppress intercell multiple access interference; (3) It cannot be applied in downlink channels. Adaptive multiuser detector eliminates the need to know the signature waveforms and the timing of the interferes and has to need training data sequences for every active user. But the frequent use of training sequence is certainly a waste of channel bandwidth.Research shows that with the prior knowledge of only the signature waveform and timing of the user of interest, blind adaptive multiuser detector can effectively detect data symbol of the desired user without training data sequence for every active user . It is especially attractive for the downlinks and suppressing intercell MAI.When multiuser detector is adapted in blind mode, it usually adopts eignvalue decomposition or singularvalue decomposition of received sample correlation matrix and tracking alrithgms, which result in high computational complexity. At the same time, approximation computation in tracking alrithgms also result in slow convergence. To overcome these shortcomes, a Interference-Space-Based blind adaptive MMSE linear detector and the corresponding tracking algorithm based interference correlation matrix is proposed. Simulation also show that the detector has strong robust.