Title :
A study on MMSE combining for MC-CDMA
Author :
Sato, Isao ; Fujii, Temya
Author_Institution :
Inf. & Commun. Labs., Japan Telecom Co., Ltd, Tokyo, Japan
Abstract :
In MC-CDMA system, the combining method based on MMSE criterion is well known as one of the methods that reduce multiple access interference. There are two cases of code spreading; in frequency domain and in time domain. In this paper, we analyse the receiving characteristics using MMSE combining in time-domain code spreading. MMSE combining in time domain cannot work effectively in slow fading channels, because time diversity affected by code spreading cannot be obtained. So, we propose a code spreading method to maximally bring out the effect of MMSE; in this method chips of the spreading code are separated spatially in the time domain so as to reduce time correlation of received level fluctuation and obtain time diversity effect as much as possible. We clarified the proposed method dramatically improved receiving characteristics in slow-to-fast fading environments as time interval between chips is wider.
Keywords :
code division multiple access; diversity reception; least mean squares methods; time-varying networks; MC-CDMA; MMSE criterion; code division multiple access; code spreading; frequency domain; minimum mean squared error; slow-to-fast fading environments; time correlation; time diversity; time domain; Degradation; Diversity reception; Fading; Frequency domain analysis; Laboratories; Multicarrier code division multiple access; Multiple access interference; Telecommunications; Time domain analysis; Transmitters;
Conference_Titel :
Vehicular Technology Conference, 2003. VTC 2003-Spring. The 57th IEEE Semiannual
Print_ISBN :
0-7803-7757-5
DOI :
10.1109/VETECS.2003.1207567