Abstract
We present a reduced complexity switching mechanism which uses either matched filter or Parallel Interference Cancellation (PIC) detector based on channel characteristics. The main criterion of taking PIC detector is that it has less Bit Error Rate (BER) and less processing delay than other nonlinear multiuser detectors. This proposed detector reduces overall complexity while maintaining the same performance as PIC detector. The switching mechanism is exploited by performance complexity tradeoff between matched filter detector and PIC detector.
Highlights
In a Code Division Multiple Access (CDMA) system, several users transmit their signals simultaneously over a common channel
It is required to demodulate the information symbol sequences of these users, upon reception of the sum of transmitted signals of all the users in the presence of additive noise This situation arises in a variety of communication systems such as wireless communication and other multipoint to multipoint multiple access networks
With the above discussion in mind, this paper presents a switching mechanism that significantly reduces the complexity in multiuser detection
Summary
In a Code Division Multiple Access (CDMA) system, several users transmit their signals simultaneously over a common channel. Conventional CDMA detectors such as matched filter[1] and RAKE combiner[2] are optimized for detecting the signal of a single desired user These conventional detectors are inefficient, because the interference is treated as noise and there is no utilization of the available knowledge of spreading sequences of the interferers. The computational complexity of this detector was linear with respect to number of users and delay introduced was much less than serial method[10] This prompts us to take PIC detector for switching mechanism in our paper. In practical situations, when only few users are present on the channel, complexity can be saved by not using PIC method This detector does not degrade the performance as the output will be same as PIC detector even if it is not used all the time and computational complexity will be reduced. In situations, when BER of both the detectors is same, this computational requirement can be saved by making a judicious choice to conventional detector
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