Equalization With Oversampling in Multiuser CDMA Systems
Abstract
Some of the major challenges in the design of new generation wireless mobile systems are the suppression of multiuser interference (MUI) and intersymbol interference (ISI) within a single user created by multipath propagation. Both of these problems were addressed successfully in a recent design of A Mutually-Orthogonal Usercode-Receiver (AMOUR) for asynchronous or quasi-synchronous CDMA systems. AMOUR converts a multiuser CDMA system into parallel single-user systems regardless of the multipath and guarantees ISI mitigation irrespective of the channel null locations. However, the noise amplification at the receiver can be significant in some multipath channels. In this paper, the authors propose to oversample the received signal as a way of improving the performance of AMOUR systems. They design Fractionally-Spaced AMOUR (FSAMOUR) receivers with integral and rational amounts of oversampling and compare their performance to the conventional method. An important point often overlooked in the design of zero-forcing channel equalizers is that sometimes they are not unique. This becomes especially significant in multiuser applications where, as they will show, the nonuniqueness is practically guaranteed. They exploit this flexibility in the design of AMOUR and FSAMOUR receivers and achieve noticeable improvements in performance. (11 figures, 23 refs.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 09, 2004
- Accession Number
- ADA428061
Entities
People
- Bojan Vrelj
- Palghat Vaidyanathan
Organizations
- California Institute of Technology