3G Long Term Evolution, which aims for various mobile multimedia services provision by enhanced wireless performance, proposes the VoIP-based voice service through the PS domain. When delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in the existing 3G systems which provide the CS domain based voice service. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as the unit for the transmission resources, it becomes necessary to develop new types of resource management schemes. This paper proposes a MAC layer PRB scheduling algorithm for the efficient VoIP service in 3G LTE and shows the simulation results regarding its performance. The key idea of the algorithm consists of two parts; dynamic activation of a VoIP priority mode for the voice QoS satisfaction and adaptive adjustment of the VoIP priority mode duration in order to minimize the performance degradation induced by its priority mode application.
In this paper, we propose a ping-pong avoidance algorithm capable of effectively alleviating the unnecessary vertical handovers between 3G cellular and WLAN hotspots. The proposed algorithm determine the appropriate time at which a terminal should initiate a handover. It can be classified into two major schemes: One is designed to separate the single vertical handover threshold; the other to estimate the transition of the beacon signal strengths received by the terminal from WLAN hotspots on the basis of the least square approach. The aim of this study is to prevent such performance degradations as the increase of the service interruption time which follows unnecessary vertical handovers.
In typical deployments of infrastructure wireless mesh networks, mesh clients are directly connected to a mesh router. The mesh routers form a multi-hop wireless mesh backbone to provide connectivity to the Internet. In this paper, we propose and evaluate a set of distributed algorithms that enable mesh clients to form a multi-hop wireless relay network to have access to the mesh backbone. The proposed algorithms include path discovery, channel allocation, path selection, and local tuning of the resulting relay network. Results show that the performance of the relay network formed by our algorithms is very close to the optimal performance that the network can achieve. 1
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