Research On Algorithm Of Multi-user Detection In The 3rd Generation

This paper proposed a receiver that combined smart antenna with Multi-user Detection(MUD) based on the third generation mobile communication systems. We also simulated in the two aspects:the system capacity and bit error rate and prove the correctness of the conclusions.With the sharp increasing of social needs in the exchange of information and rapidly spreading of personal mobile communications, the spectrum has become increasingly valuable resources. In the base of existing TDMA, FDMA and CDMA, smart antenna technology introduces the fourth dimension multiplexed address made:SDMA. Users can be distinguished by the space communication path although they have the same time slot, frequency and address code. So SDMA can multiplied to extend system capacity. As the key technology of the third generation communication systems, smart antenna has been attached importance to all over the world, because it has certain advantages in both improving system capacity and reducing neighbor cell interference.On the other hand, MUD technology is not a new study, both domestic and foreign scholars have given an integrated algorithm. Many new detections such as based higher order statistics, neural network and support vector machine have become mature. In this paper we adopt Multistage Parallel Interference Cancelation(MPIC), because it can make compromising in reducing complexity and increasing system performance.In this paper we first introduce the third generation mobile communication systems and the development status of MUD, then discuss several typical MUD, analyzes their realization complicity and advantage or disadvantages, and make comparison among these detections. Secondly, we tell the conception and algorithm theory of smart antenna, introduces the LMS algorithm of adaptive antenna array analyze multipath effect. Compared with two beamforming nets:CB configuration and SB configuration. We draw the conclusion that, although SB is more complex than CB but it is more superior in system function.At last, we propose the receiver that combine smart antenna with MPIC, with the assumption the perfect channel estimates have been obtained. According to MMSE detection, the weights can be found by adaptive algorithms, that is used to combing the soft-decision output user data after MPIC processing and antenna array. Combined with these two technology, in the special domain, we use smart antenna to resistance multipath interference and neighbor cell interference; in the time domain, we use MPIC to resistance multiple access and inter-symbol interference.