Abstract
The recently developed blind adaptive techniques for multiuser detection in code division multiple access (CDMA) systems offer an attractive compromise of performance and complexity. However, the desire to further reduce complexity at the mobile unit has led to the investigation of techniques that move signal processing from the mobile unit to the base station. In this paper, we investigate transmitter precoding for downlink time division duplex (TDD) code division multiple access (CDMA) communications. In particular, we develop a linear minimum mean square error precoding strategy using blind channel estimation for fading multipath channels that allows for simple matched filtering at the mobile unit and is easy to make adaptive. We also present a performance analysis using tools developed for the analysis of conventional (receiver-based) linear blind multiuser detection in unknown channels. We compare the analytical and simulation results to traditional receiver-based blind multiuser detection. It is seen that transmitter precoding offers a reasonable alternative for TDD-mode CDMA when minimizing computational complexity at the mobile unit is a priority.
Highlights
The demand for capacity and performance in multiple access wireless systems has spurred the development of sophisticated signal processing techniques for signal reception [1, 2]
Researchers have recently begun investigating signal processing techniques that move computational complexity from the mobile unit to the base station, where it can be managed more efficiently. These techniques involve some kind of transmitter-based multiuser interference cancellation at the base station and simple linear processing, for example, matched filtering, at the mobile unit. They are appealing for time division duplex code division multiple access (TDDCDMA) [3] since the same carrier is used for both uplink and downlink in different time slots
We present a performance analysis using tools developed for the analysis of blind multiuser detection with blind channel estimation [9]
Summary
The demand for capacity and performance in multiple access wireless systems has spurred the development of sophisticated signal processing techniques for signal reception [1, 2]. Researchers have recently begun investigating signal processing techniques that move computational complexity from the mobile unit to the base station, where it can be managed more efficiently. Speaking, these techniques involve some kind of transmitter-based multiuser interference cancellation at the base station (precoding) and simple linear processing, for example, matched filtering, at the mobile unit. These techniques involve some kind of transmitter-based multiuser interference cancellation at the base station (precoding) and simple linear processing, for example, matched filtering, at the mobile unit They are appealing for time division duplex code division multiple access (TDDCDMA) [3] since the same carrier is used for both uplink and downlink in different time slots.
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