Performance improvement in DS-spread spectrum CDMA systems using a pre- and a post-RAKE

Mobile communications systems based on code division multiple access (CDMA) and direct sequence spread spectrum techniques have been gaining a lot of ground lately. The RAKE receiver is a well known technique in spread spectrum systems, which is used to obtain signal diversity in multipath environments. In TDD systems, a technique known as pre-RAKE has been proposed recently, in which the signal processing is transferred to the transmitter, and it has been shown that this technique provides a capacity increase in the downlink. In this paper we propose a combination of both methods and show that a substantial performance improvement can be reached this way.