Performance Evaluation of a Novel CDMA Detection Technique: The Two-State Approach
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Performance Evaluation of a Novel CDMA Detection Technique: The Two-State Approach Enrico Del Re Department of Electronics and Telecommunications (DET), University of Florence, Via di Santa Marta 3, 50139 Florence, Italy Email: [email protected]
Lorenzo Mucchi Department of Electronics and Telecommunications (DET), University of Florence, Via di Santa Marta 3, 50139 Florence, Italy Email: [email protected]
Luca Simone Ronga CNIT Florence Unit, University of Florence, Via di Santa Marta 3, 50139 Florence, Italy Email: [email protected] Received 1 August 2003; Revised 4 March 2004 The use of code division multiple access (CDMA) makes third-generation wireless systems interference limited rather than noise limited. The research for new methods to reduce interference and increase efficiency led us to formulate a signaling method where fast impulsive silence states are mapped on zero-energy symbols. The theoretical formulation of the optimum receiver is reported and the asymptotic multiuser efficiency (AME) as well as an upper bound of the probability of error have been derived and applied to the conventional receiver and the decorrelating detector. Moreover, computer simulations have been performed to show the advantages of the proposed two-state scheme over the traditional single-state receiver in a multiuser CDMA system operating in a multipath fading channel. Keywords and phrases: code division multiple access, communication signal theory, wireless communications, impulsive information sources.
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INTRODUCTION
Bandwidth represents the last challenge in wireless personal communications. Due to the average increase of the radiolink bandwidth requirements and the hostile urban radio channel for the interference-limited CDMA, the system capacity will meet its physical limitations even in a moderated deployment scenario. Moreover, the grown of the short-range wireless communication world (IEEE 802.11x, ultra-wideband, etc.) has been due to the rising request for higher and higher data transfers and capacity. Future wireless techniques have to answer two fundamental issues: how to guarantee fast data transfer and how to share the limited resource with a larger and larger number of users. Hence, every technology capable of increasing the spectral efficiency of the radio link deserves a particular attention in the future wireless systems. Typical short-range wireless transmissions involve high-capacity broadband link for few times per connection. Burst communications are normally identified by regular periods of data transfer (talk state) followed by a silence period.
The proposed two-state technique takes advantage of low probability of talk communications. Power consumption at the handheld terminal is another key issue. Mobile terminals are requested to operate complex computational tasks at the expense of a reduced duration of the batteries. The techniques able to save energy by optimizing the transmission scheme play a fundamental role in the design phase of the next-generation wireless communications. Those consid
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