The Research Of Multi-user Detection Algorithm Based On WCDMA

In recent years, the broadband mobiles have gained the rapid progress. The third generation of mobile communication is a broadband communication system built above the basis of ITUIMT-2000 which has very good network compatible and can roam between different systems in the whole world range. Currently, the third generation standards that International Telecommunication Union has accepted are mainly three kinds the following standards: WCDMA, CDMA2000 and TD-SCDMA, which base on the technology of CDMA.WCDMA brought forward by Europe ETSI (the third generation of Europe standardizes organization), is also basically built above narrow belt of CDMA . Since CDMA is an interrupted and restricted system, its capacities and the function are restricted by multiple addresses interrupt, while multi-user detection algorithm can reduce much the interrupts of multiple addresses and multiple paths, which can entirely reduce every user's error code function. Therefore, adopting multi-user detection algorithm in WCDMA system can be effective improving the systematic function's index.The paper analyses the necessity of adopting multi-user detection algorithm theoretically according to the traditional mathematic model of CDMA expanding frequency spectrum communication, then carrying out theoretical analysis and verifying to how multi-user detect algorithm improve system function .The verifying method is that adding multi-user detect algorithm to the receiver of WCDMA's physical layer which is under the Frequency Division Duplex pattern and verifying the improvement of the algorithm to system function according to the comparison of error code rate by using the tool of MATLAB to simulate system function. The protocol of physical layer under Frequency Division Duplex pattern using in physical layer of WCDMA system includes frame structure, coding in uplink physical route , multiplex , spreading, and modulate in uplink. During simulation, adopts MATLAB to simulate the uplink of single user and route WCDMA launching and receiving system by simulating emulation according to WCDMA uplink protocol and acquires error code rate, meanwhile, adopts multi-user detection algorithm to simulate capacities of multi-user and multi-route based on the simulation of single user and route. The result of simulation demonstrates that after adopting multi-user detection algorithm ,the error code rate of system reduce much, which has very big rise to systematic function.The simulating platform the paper designed can be also applied to the other simulations Of WCDMA system by single modifies, such as the downlink WCDMA simulation, intelligent antenna, code design, power control and so on, which improve system function and have important reference value to latter research.