Candidate Technologies for Next-Generation Wireless Access Systems

Because of the spectacular success that they have experienced in recent years, Wireless Local Area Networks have emerged as a key technology in the wireless evolution towards 4th-generation IP-based networks. Indeed, they are already competing with cellular networks to deliver data services in hotspots. Latest systems provide multimedia quality-of-service support at data rates of up to 54 Mbps, and are expected to play important roles in the enterprise and home networking environments. Nevertheless, the next generation of short-range wireless communication systems is called upon to fulfill very challenging requirements that far exceed what "state-of-the-art" systems can provide. In fact, they will have to compare positively with wired technologies in order to provide real broadband wireless services. This report aims at identifying the underlying requirements and the technologies that will have to be employed to meet these requirements. Because the requirements in data rate and link quality are virtually impossible to satisfy with single-antenna systems, we pay special attention to multiple-antenna systems. We focus on the specific and significant design challenges that will have to be addressed at both the physical layer and the data link layer. Although this survey is not intended to be exhaustive, we try to point out important research activities that should be conducted in order to allow future systems to fully exploit the benefits that emerging transmission technologies provide.