ABSTRACT

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WCDMA-TDD is one of the main techniques in the 3^rd generation mobile communication system. Researchers, manufacturers and users over the world are paying more and more attentions to its development. Based on the cooperative project with Fujistu Research & Development Center (FRDC), this paper focuses on the key points of RAKE receiving technique in WCDMA-TDD system, including multipath search and channel estimation.
After the introduction of WCDMA-TDD system, usage of RAKE receiving technique in WCDMA-FDD and WCDMA-TDD system are compared. The result is that midamble must be used in multipath searching. The author presents the mathematical expressions of basis three-step RAKE receiving algorithm with performance analyses. The common part of midamble acquisition and multipath search on DCH is concluded as a problem of PN sequence's phase search in WCDMA-TDD. Correlation based algorithm is presented here with their algorithm descriptions, performance analyses and simulation results.
Based on above algorithm anlyses, software simulation is presentd under the ITU recommended channel models that are proposed speacial for evaluating the 3^rd generation mobile communication systems. From the results, modifications on multipath search range, multipath combine range and the number of finger in RAKE receiver are proposed to improve the performance of RAKE receiver. A key factor in RAKE receiving performance, the accuracy of multipath search using midamble is surveyed here to find that multiplexed timeslot result combining is need for WCDMA-TDD system. A multipath search algorithm using adaptive threshold is presented for implementation convenience. Moreover, multiplexed channel estimation is proposed for typical environment of WCDMA-TDD system.
At last, this paper describes design and implementation of multiplexing and channel coding part with convolutional code for WCDMA-TDD system using Aptix System Explorer MP3C.
In this paper, a complete process of designing a convolutional encoder and a Viterbi decoder is presented. And a multiplexing part for WCDMA-TDD system is also designed according to 3GPP specification. In this process, an integrated design environment with simulation and synthesis tools are used to verify and optimize the design. The final design is targeted for Xilinx Virtex-E FPGA. Through the use of the simulation and synthesis tools, mundane tasks could be reduced and important design parameters could be defined with more accuracy. This contributes to reducing design iterations and assuring early success. All the designs are already verified on testbed that is built on Aptix System Explorer MP3C.