Title :
R-conjugate codes for multi-code CDMA
Author :
Tarr, Adam ; Zoltowski, Michael D.
Author_Institution :
Dept. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA
Abstract :
The multi-code CDMA problem, and the corresponding data and noise model is discussed. The problem of "crosstalk", which occurs when using an MMSE receiver in colored noise, is addressed. A method to avoid "crosstalk", by choosing the eigenvectors of the interference plus noise matrix as codes, is introduced. This approach is shown to produce codes that are orthogonal not only in the conventional sense, but also with respect to the interference plus noise matrix. The gain on the codes is shown to be inversely proportional to the corresponding eigenvalue. Simulation results demonstrate that the codes corresponding to the smallest eigenvalues dramatically outperform the MMSE receiver for Walsh-Hadamard codes in terms of mean-square error (MSE).
Keywords :
channel coding; code division multiple access; crosstalk; eigenvalues and eigenfunctions; least mean squares methods; matrix algebra; mobile radio; receivers; MMSE receiver; MSE; R-conjugate codes; colored noise; crosstalk; data model; eigenvalue; eigenvectors; interference plus noise matrix; mean-square error; multi-code CDMA; noise model; Colored noise; Crosstalk; Data mining; Data models; Eigenvalues and eigenfunctions; Error correction; Error correction codes; Interference; Multiaccess communication; Transmitters;
Conference_Titel :
Acoustics, Speech, and Signal Processing, 2003. Proceedings. (ICASSP '03). 2003 IEEE International Conference on
Print_ISBN :
0-7803-7663-3
DOI :
10.1109/ICASSP.2003.1202571
