A MAC Protocol for MIMO Based IEEE 802.11 Wireless Local Area Networks

An increasing number of wireless devices and services imposes higher demands for wireless networks´ capacity. Likewise, contemporary bandwidth requirements of each user in the network rise significantly, being a mixture of traffic types such as Web surfing, file transfer protocol (FTP), video, video-teleconference, and voice. Multiple input-multiple output (MIMO) techniques are recognized as methods that can meet these requirements, since they significantly increase the capacity of wireless networks, without additional bandwidth or transmission power. With a MIMO physical layer (PHY), the transmission channel gets a layered structure. Consequently, support from higher layers with a cross-layer approach that provides efficient management of the channel´s spatial layers, can significantly increase the network´s performance on both link and system level. In this paper a high capacity medium access control (MAC) protocol for MIMO support is presented. The proposed protocol is based on IEEE 802.11 standard, and provides a flexible and scalable support for multiple antenna terminals, backwards compatible with legacy stations.