Performance Analysis of Decorrelating Detectors for Dual-rate Synchronous DS/CDMA Systems Over Frequency-selective Rayleigh Fading Channels PDF Download

Author: Xiangtao Li
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Languages : en
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Book Description
In this thesis, the performance of a decorrelating-based multiuser detector for frequency-selective channels is discussed. The users transmit data at two different rates are instead of one single rate. According to their transmission rates, the users are classified into two groups, a group of high rate users and a group of low rate users. It is assumed that over the time interval [0, T o], the low rate users transmit one bit, while the high rate users transmit M bits of information. At the receiving end, two types of decorrelators are examined to decode the signals: a low rate decorrelator (LRD) and a high rate decorrelator (HRD). The LRD makes a decoding decision for every T o seconds and views one high rate user as M effective low rate users. The HRD makes a decision for every T 1 = T o / M seconds and detects a bit from a low rate user M times during the time interval[0, T o]. The signals from the two groups are transmitted over frequency-selective multipath Rayleigh fading channels. The maximal ratio combining (MRC) technique is used in two parts of the receivers. First, the multipath diversity and MRC diversity reception method are utilized in the receivers to combat against the multipath fading. Secondly, in HRD, MRC is employed to implement a soft decoding rule for the low rate users. The error probability and asymptotic multiuser efficiency for both types of decorrelators will be evaluated and the simulation results given. It can be seen in the simulation results that the LRD is superior to the HRD in the performance for both low rate and high rate users.