Code-aided joint channel and frequency offset estimation for DS-CDMA

This paper deals with joint data detection, synchronization and channel parameter estimation for Direct-Sequence Code Division Multiple Access (DS-CDMA) systems over frequency selective channels. In low-SNR environments, conventional data-aided estimation algorithms may require an unacceptably large number of pilot symbols in order to obtain sufficiently accurate estimates of the channel and synchronization parameters. Especially frequency offset estimation results in a significant loss in spectral efficiency. In this contribution, we consider several code-aided estimation schemes which can be incorporated in an iterative turbo detection scheme. We consider the Expectation Maximization (EM) algorithm as well as the Space Alternating Generalized Expectation Maximization (SAGE) algorithm as tools to develop codeaided estimation algorithms for a variety of scenarios. We pay special attention to the issue of computational complexity, and propose some complexity-reducing approximations. We...

• Type: Journal
• Year: 2006
• Where: JSAC
• Authors: Mamoun Guenach, Frederik Simoens, Henk Wymeersch, Marc Moeneclaey
• Keywords: Code-aided Estimation, Estimation, Estimation Algorithms, JSAC 2006