08-16-2017, 10:35 PM
BLAST is an wireless communications
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INTRODUCTION
The explosive growth of both the wireless industry and the Internet is creating a huge market opportunity for wireless data access. Limited internet access, at very low speeds, is already available as an enhancement to some existing cellular systems. However those systems were designed with purpose of providing voice services and at most short messaging, but not fast data transfer. Traditional wireless technologies are not very well suited to meet the demanding requirements of providing very high data rates with the ubiquity, mobility and portability characteristics of cellular systems. Increased use of antenna arrays appears to be the only means of enabling the type of data rates and capacities needed for wireless internet and multimedia services.
FUNDAMENTAL LIMITATIONS IN WIRELESS DATA ACESS
Ever since the dawn of information age, capacity has been the principal metric used to asses the value of a communication system. Since the existing cellular system were devised almost exclusively for telephony, user data rates low .Infact the user data were reduced to the minimum level and traded for additional users. The value of a system is no longer defined only by how many users it can support, but also by its ability to provide high peak rates to individual users. Thus in the age of wireless data, user data rates surges as an important metric.
SPACE: THE LAST FRONTIER
As a key ingredient in the design of more spectrally efficient systems. In recent years space has become the last frontier. The entire concept of frequency reuse on which cellular systems are based constitutes a simple way to exploit the spatial dimension. Cell sectorisation, a widespread procedure that reduces interference can also be regarded as a form of spatial processing. Moreover, even though the system capacity is ultimately bounded, the area capacity on a per base station basis. Here, base station antenna array are the enabling tools for wide range of spatial processing techniques devised to enhance desired to enhance desired signals and mitigate interference. Coverage can be extended and tighter user packaging becomes possible, enabling in turn larger cell sizes and higher capacity can be extended even beyond the point at which every unit of bandwidth is effectively used in every sector through space division multiple access (SDMA).