Showing papers on "Multi-user MIMO published in 1993"

C-MCMA: a new multiple access protocol for centralized wireless local networks

Abstract: The development of wireless local area networks depends, to a large extent, on the availability of flexible and efficient multiple access techniques that cope with the constraints imposed by the wireless propagation environment. In this paper we consider centralized network topologies, with a base station exchanging data packets with a set of portable terminals. We propose a new multiple access protocol whereby the portable terminals compete for the uplink access to the channel with minipackets in response to controlling commands, issued by the base station. Accordingly, the protocol is called centralized minipacket competition multiple access (C-MCMA). In order to judge on the efficiency of C-MCMA its performance is compared with that of the busy channel multiple access protocol with collision detection (BCMA/CD), taking into account receiver capture effects and downlink traffic. It is concluded that for a wide range of values for the parameters of the models considered C-MCMA outperforms BCMA/CD. >

Interference, sensitivity and capacity calculations for measurement-based wireless access spectrum sharing

Abstract: Interference caused by multiple uncoordinated low-power wireless access system transmitters to fixed point-to-point microwave receivers is analyzed. The analysis shows that the density of wireless access system users that can share spectrum with a point-to-point microwave system depends critically on the propagation relation, the threshold of detecting energy from point-to-point transmitters, and the allowable interference into point-to-point receivers. It is found that for reasonable assumptions of point-to-point link, wireless access system, and propagation parameters, a wireless access system employing measurement-based interference avoidance must detect energy of point-to-point transmissions far below the thermal noise floor of the wireless access system receivers which would increase their complexity. The implications to local exchange networks of wireless system alternatives that could provide access to those networks are addressed.