Adaptive Random Access with Beam-forming in 4G Mobile Networks

Packet switching replaces the traditional circuit switching and with the wireless extension of the Internet next-generation air-interfaces have to cope with bursty IP traffic. Transmit resources on the air-interface have to be allocated on demand and in a very flexible manner. At the same time, the delay requirements are more stringent putting high challenges on the random access component of future wireless systems. In this paper a novel random access scheme exploiting the advantages of multiple-input multiple-output (MIMO) systems is presented that considerably enhances the spectral efficiency. Besides a heuristic algorithm for beam-forming the advantages are described and the performance gains are derived. Since MIMO will be part of 4G mobile networks and random access is a basic component in every wireless system the new approach is a promising candidate for systems beyond 3G