Varying Channel Quality Research Articles

A proposal of multihop mesh network architecture featuring adaptive network control for broadband fixed wireless access systems

AbstractAs a means of flexibly providing large‐capacity access infrastructure at a low cost, the broadband fixed wireless access (BFWA) system using millimeter‐wave and quasi‐millimeter‐wave frequencies is promising. In general, wireless channel quality variations are significant due to rainfall in wireless systems using millimeter‐wave and quasi‐millimeter‐wave frequencies. Hence, deterioration of the channel working rate is a problem. In this paper, a multihop wireless access system with a mesh configuration is proposed that can deploy a millimeter‐ and quasi‐millimeter‐wave BFWA system at a high quality and a high density. In the proposed system, deterioration of the channel working rate due to wireless channel quality variations is avoided. In addition, the capacity is maximized by adaptively assigning the network resources for variations of the traffic demand and wireless channel transmission capacity. Further, as an adaptive control used in the proposed system, wireless channel assignment for a wireless link and load distribution among several paths within the mesh network are discussed. The problem is formulated as a mixed nonlinear optimization problem. In addition, a heuristic solution is proposed for solving the problem within a realistic time for a network of the anticipated size. The proposed algorithm is applied to a mesh network and the behavior and the performance of the algorithm are evaluated to prove its effectiveness. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(6): 22–33, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10133

QoS management with dynamic bearer selection schemes

This paper presents an evaluation of a radio level QoS management scheme developed to ensure the maintenance of QoS contracts. The concept of QoS contract is defined as the specification of the quality requirement for various types of services. According to the contracted QoS, a dynamic bearer selection is performed to adapt the link to the channel quality variations. Terrestrial Trunked Radio system (TETRA) presents itself as a suitable platform for illustrating the concept of QoS contract. This arises from its feature-rich bearer services that support data and voice with varying levels of error protection. The generic QoS management scheme presented in this paper has been applied to a private mobile radio system but it also represents an appropriate platform for multi-vendor, multi-technology and multimedia environments such as those found with 3G systems.

Providing quality of service over a shared wireless link

We propose an efficient way to support quality of service of multiple real-time data users sharing a wireless channel. We show how scheduling algorithms exploiting asynchronous variations of channel quality can be used to maximize the channel capacity (i.e., maximize the number of users that can be supported with the desired QoS).