Cross-Layer Resource Allocation Algorithms in Wireless Networks with antenna Arrays

Title of Dissertation: CROSS-LAYER RESOURCE ALLOCATION ALGORITHMS IN WIRELESS NETWORKS WITH ANTENNA ARRAYS Tianmin Ren, Doctor of Philosophy, 2005 Dissertation directed by: Professor Leandros Tassiulas Department of Electrical and Computer Engineering The application of antenna array is a promising approach to improving the capacity of a wireless network. In this dissertation, we study the application of antenna arrays at the base stations (BSs) in a wireless cellular network. We focus on the downlink transmission. This application requires the BSs be aware of the locations and channel conditions of the mobile users. Towards this end, we propose a family of MAC layer protocols that enable a base station to learn the locations and channel conditions of a number of intended users. Our simulation results demonstrate that the inter-cell interference significantly degrades the system performance of the previously proposed beamforming algorithms in terms of packet loss probability (PLP) in a multi-cell environment. To cope with inter-cell interference, we propose beamforming algorithms that achieve target PLP in the presence of random inter-cell interference. The application of antenna array on the physical layer has great impact on the protocols of higher layers. Novel MAC algorithms and protocols need to be designed to take advantage of the capacity enhancement provided by antenna array on the physical layer. In this dissertation, the issue of designing a downlink scheduling policy with base station antenna arrays is studied. We derive an optimal scheduling policy that achieves the throughput region. Then, based on the structure of the derived optimal policy, we propose two heuristic scheduling algorithms. The interference experienced by each node in an ad-hoc network exhibits stochastic nature similar to the inter-cell interference in a cellular network. We propose a power control algorithm in a distributed scheme to achieve target PLP. Furthermore, the proposed power control algorithm is shown to minimize the aggregate transmission power given the PLP constraint. In the above problems, we mainly consider the non-real-time traffic where throughput is the QoS parameter of concern. On the other hand, delay is an important QoS parameter for real time traffic. In this dissertation, we also consider the scheduling of real time packets by a BS with awareness of physical layer channel conditions of different users. CROSS-LAYER RESOURCE ALLOCATION ALGORITHMS IN WIRELESS NETWORKS WITH ANTENNA ARRAYS