User cooperation diversity. Part I. System description

Mobile users' data rate and quality of service are limited by the fact that, within the duration of any given call, they experience severe variations in signal attenuation, thereby necessitating the use of some type of diversity. In this two-part paper, we propose a new form of spatial diversity, in which diversity gains are achieved via the cooperation of mobile users. Part I describes the user cooperation strategy, while Part II (see ibid., p.1939-48) focuses on implementation issues and performance analysis. Results show that, even though the interuser channel is noisy, cooperation leads not only to an increase in capacity for both users but also to a more robust system, where users' achievable rates are less susceptible to channel variations.

I. Introduction

Next-Generation wireless communications (third generation and beyond) will bear little resemblance to first- and second-generation, mostly voice cellular systems. In order to meet the demands of multirate multimedia communications, next-generation cellular systems must employ advanced algorithms and techniques that not only increase the data rate, but also enable the system to guarantee the quality of service (QoS) desired by the various media classes. The techniques currently being investigated for meeting next-generation goals include advanced signal processing, tailoring system components (such as coding, modulation, and detection) specifically for the wireless environment, departing from classic dichotomies (such as between source and channel coding), and using various forms of diversity [1]–[5]. Among these techniques, diversity is of primary importance due to the nature of the wireless environment.