Blind decorrelating RAKE receivers for long-code WCDMA |
| |
Authors: | Lang Tong van der Veen A.-J. Dewilde P. Youngchul Sung |
| |
Affiliation: | Sch. of Electr. & Comput. Eng., Cornell Univ., Ithaca, NY, USA; |
| |
Abstract: | The problem of blind and semiblind channel estimation and symbol detection is considered for long-code wideband code division multiple access (CDMA) systems, including systems with multirate and multicode transmissions. A decorrelating matched filter, implemented efficiently in state-space, eliminates multiaccess interference and produces a bank of vector processes. Each vector process spans a one-dimensional (1-D) subspace from which channel parameters and data symbols of one user are estimated jointly by least squares. A new identifiability condition is established, which suggests that channels unidentifiable, in short-code CDMA systems are almost surely identifiable when aperiodic spreading codes are used. The decorrelating matched filter is implemented efficiently based on time-varying state-space realizations that exploit the structure of sparsity of the code matrix. The mean square error of the estimated channel is compared to the Cramer-Rao bound, and a bit error rate (BER) expression for the proposed algorithm is presented. |
| |
Keywords: | |
|
|