Receiver algorithms that enable multi-mode baseband terminals

• Main Author: Li, Yushan
• Published: University of Edinburgh 2005
• Subjects: 621.382
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653872

Wireless communications is rapidly moving towards so called 4G wireless systems. This has led to an increasing demand to develop integrated mobile terminals which have multi-mode capabilities, i.e. multiple communication systems can coexist. The central goal of this thesis is to determine appropriate structures and algorithms for multi-mode receivers that maximize flexibility without excessive compromise in performance. The work develops multi-mode terminals from the algorithm viewpoint, reducing receiver complexity by taking advantage of the commonalities among different specifications and receiver requirements. For example, the commonalities among DAB, DVB-T and HIPERLAN-2 physical layers are investigated and a common system clock is adopted for these communication systems. In addition, a receiver architecture combining sampling rate conversion and OFDM symbol synchronisation is also presented. The coexistence of WCDMA and OFDM systems from the perspective of using the same equalisation structure is elaborated; chip-level frequency domain equalisation for WCDMA forms a major part of this thesis. Simulation results verify the effectiveness of the proposed equalisation algorithms. Moreover, SC-FDE with more flexible structures, i.e. with a varying length feedback filter or without cyclic prefix, is examined. Then the importance of an accurate channel estimation for practical spread spectrum systems is emphasized. A code-multiplexed pilot sequence is used for the purpose of channel estimation in both WCDMA and CP-CDMA systems and to maintain bandwidth efficiency. System performance is improved significantly by a proposed joint iterative channel estimation and parallel interference cancellation algorithm. Finally conclusions are drawn and suggestions for further work presented.