Xia, B. and Wang, J.Z. and Sawahashi, M. (2008) Performance Analysis of MMSE Detectors for High Speed VSF-OFCDM. IEEE Transactions on Communications, 56 (12). pp. 2013-2019. ISSN 0090-6778.
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This letter investigates the effect of Doppler frequency shift on the performance of MMSE receivers for high speed variable spreading factor (VSF) orthogonal frequency and code division multiplexing (OFCDM) systems in broadband wireless communications. In VSF-OFCDM systems, the existence of multicode interference (MCI) resulting from multiple code channels occupying the same bandwidth degrades the performance. A full MMSE receiver is analytically studied in this letter, exploiting correlation properties among transmitted data on different subcarriers to combat the MCI. Furthermore, considering the fact that the fast time-varying fading destroys the orthogonality of the time domain spreading codes and thus introduces time domain MCI, its effect on system performance is evaluated accurately. It is also shown that it is expected to use time domain spreading factor N-T of 8 for a large range of Doppler frequencies, and frequency domain spreading factor as large as possible, especially in high signal to noise ratio. Moreover, in order to improve performance, the pilot channel should occupy around 20% to 25% of the total transmitted power for a large range of Doppler.
|Uncontrolled keywords:||Doppler frequency; MMSE; OFDM; spread spectrum|
|Subjects:||T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101 Telecommunications > TK5103.4 Broadband (inc wireless broadband)|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Engineering and Digital Arts > Broadband & Wireless Communications|
|Depositing User:||Louise Dorman|
|Date Deposited:||10 Mar 2009 14:33|
|Last Modified:||21 Apr 2009 10:27|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/15343 (The current URI for this page, for reference purposes)|
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