Cross-layer optimized conditions for QoS support in multi-hop wireless networks with MIMO links

Recent advances in antenna technology made it possible to build wireless devices with more than one antenna at affordable costs. Because multiple antennas offer wireless networks a potential capacity increase, they are expected to be a key part of next-generation wireless networks to support the rapidly emerging multimedia applications characterized by their high and diverse QoS requirements. In this paper, we develop methods that exploit the benefits of multiple antennas to enable multi-hop wireless networks with flow-level QoS capabilities. We first propose a cross-layer table-driven statistical approach that allows each node to determine the amount of spatial reuse and/or multiplexing, offered by the multiple antennas, that are available to it. We then use the developed statistical approach to derive sufficient conditions under which flow rates are guaranteed to be feasible. The derived conditions are multi-layer aware in the sense that they account for cross-layer effects between the PHY and the MAC layers to support QoS at higher layers. We evaluate and compare the derived sufficient conditions via extensive simulations. We show that the conditions result in high flow acceptance rates when used in multi-hop wireless networking problems such as QoS routing and multicommodity flow problems. We also demonstrate the importance and the effect of considering cross-layer couplings into the development of flow acceptance methods.