Realization Of WCDMA Echo Cancellation And Base Station Lock System Based On Adaptive Algorithm

With the rapid development of mobile communications,a large number of base stations are required.The best way to reduce the system coverage costs is to build repeater system.Generally,the cost of repeater system is much lower than the base station.Therefore,the choice of repeater is the good solution for the mobile communication construction.But,there is some difficulties in the construction of the repeater.When the distance between the transmitting antenna and receiving antenna is too close,the transmitting signal is easily coupled to the receiving antenna,resulting in self-excited phenomenon.At the same time,a plurality of base station signals exist in the same cell and the power is almost the same,resulting in constant cell switching by the users in the cell,which affects not only call quality but also battery utilization.This phenomenon is called pilot pollution.Two problems are the technical difficulties which repeater must solve.By comparative the solutions of the traditional repeater system to such problems,this paper propose an echo cancellation system based on the adaptive algorithm.In addition,based on the physical layer principle of WCDMA,the base station synchronization can be realized by cell search technique,and then WCDMA base station locking technology can be realized via the pilot offset technology which is based on adaptive algorithm.In addition,digital frequency conversion,digital filtering,digital frequency offset correction and other digital signal processing technology is also adopted.Through using software to simulating and experiments to realization,the WCDMA echo cancellation and base station lock system,which mentioned in this paper,can accurately search several cell signals in the area where the equipment is located.After selective pilot cancellation,one of the base stations can be locked.And verify the correctness of echo cancellation and the speed of convergence.Finally,through the actual test batch products,the system can achieve better results for the base station locking,it can also resolve practical problems of pilot pollution.Once the system is poweon,the system not only can automatically adjust the corresponding parameters according to the current application environment and the working status of the hardware,but also can track the changes of the environment adaptively.Coupled with the use of frequency offset correction technology,the system can get a better cell search result.After the ICS function is turned on,the gain of the direct station is greatly enhanced and the coverage is wider.Therefore,the system can expand the coverage and improve the connection quality,and can be widely used in the field of communication.