Study On Echo Cancellation Technique In The Environment Of Mobile Communication

In mobile communication system, as an amplification and transfer device, the repeaterstation is widely used in the blind or weak areas where communication signals are difficult toreach. The repeater station has the advantages of simple structure, low cost, strong flexibilitynetwork layout and quick network construction and etc. The repeater station’s transmittingsignals are couple fed back to the receiver through outer channel and that forming the echointerference. Echo interference signals are mixed with donor signals and both of signals areamplified and transferred together. The echo signal will be amplified again if it cannoteffectively eliminate the echo interference, and thus the formation of self-excited loop. Inorder to effectively eliminate the echo interference, this paper mainly studies the algorithmsof echo cancellation in the mobile communication environment.First, it introduces the architecture of the echo cancellation system of repeater station andfocus on studying the up-down-conversion section, multi-rate transformation section and echocancellation section.Second, it presents echo cancellation technology based on DLMS algorithm. PresentDLMS algorithm on the basis of LMS adaptive algorithm and complete the modeling of echocancellation system based on DLMS algorithm. Prove the feasibility of echo cancellationtechnology through the MATLAB simulation, and then implement it on the FPGA.Then, it puts forward echo cancellation technology based on additional signal. The wholesystem algorithm is deduced and verified the correctness through simulation. And thencomplete the coding using Verilog HDL languages. Modelsim test has the same results withMATLB simulation that certifies the echo cancellation technology is feasible.Finally, this paper studies echo cancellation technology based on Space-time blockcoding. This paper introduces the basic principles of space-time coding and then deduces thetheory of echo cancellation technology based on Space-time block coding. Since the time islimited, the algorithm simulation is going to be completed next step.