Tianmin Ren

Learn More
— The use of smart antennas in extending coverage range and capacity of wireless networks dictates the employment of novel media access control protocols, with which the base station (BS) or access point (AP) provides access to users by learning their locations. We consider the class of protocols that employ beamforming and use contention-based or(More)
We study the application of antenna arrays at the base stations in a multi-cell environment. Simulation results demonstrate that the inter-cell interference significantly degrades the system performance in terms of packet loss probability (PLP) and total throughput. In order to cope with the presence of inter-cell interference in multi-cell networks we(More)
— Recent advances in the area of wireless communications have revealed the emerging need for efficient wireless access in personal, local and wide area networks. Space division multiple access (SDMA) with smart antennas at the base station is recognized as a promising means of increasing system capacity and supporting rate-demanding services. However, the(More)
A b s u a b QoS provisioning to users in the presence of volatility of the wireless channel is the most challenging issue in wireless system design. In this paper, we consider the problem ofscheduling constant bit rate (CBR) traffic packets over the wireless channel, subject to packet delivery deadline eon-straints. We cast the problem as a Markov decision(More)
— We study the downlink scheduling problem in a cellular wireless network. The base stations are equipped with antenna arrays and can transmit to more than one mobile user at any time instant, provided the users are spatially separable. In previous work, an infinite traffic demand model is used to study the physical layer beamforming and power control(More)
Several flow control algorithms have been proposed for attaining maxmin fair rates. All of these strategies use flow specific states at all nodes in the network, and are hence unsuitable for deployment in the current internet. We propose a new approach which attains maxmin fairness in unicast networks while maintaining per flow states at the edge nodes(More)
We study the issue of designing a downlink scheduling policy for a cellular network with base station antenna arrays. We derive an optimal scheduling policy that achieves the throughput region, which is a set of feasible arrival rate vectors that can be stabilized by some scheduling policy. Then, based on the structure of the derived optimal policy whose(More)
— Smart antennas constitute perhaps the most promising means of increasing capacity in wireless systems by allowing intra-cell channel reuse by several users. The employment of smart antennas at the physical layer raises significant issues in medium access control (MAC) layer. In this paper, we study the impact of smart antennas on MAC layer channel(More)
  • 1