**List of acronyms and abbreviations**



## **7. References**

74 Wireless Mesh Networks – Efficient Link Scheduling, Channel Assignment and Network Planning Strategies

one proposed in [32], can be used which may lead to a better performance.

more realistic propagation models such as Shadowing, Rayleigh-fading.

Other schemes for building the tree topology with the required node degree, such as the

 The propagation model used is free-space model or two-ray model depending upon the cross-over distance. The performance of the proposed algorithm may be tested under

 The carrier sensing range is generally assumed to be twice the transmission range. However, carrier sensing range is a tunable parameter and an optimally tuned carrier sensing range can improve the network throughput in wireless mesh networks by enhancing the spatial frequency reuse and reducing collisions [33]. The performance of the

 All the traffic in a WMN is directed towards the gateway. The traffic bottleneck at the gateway is the main reason of the capacity limitation of a WMN. The use of multiple gateways can increase the capacity of the WMN by preventing the formation of traffic bottlenecks [35]. The proposed algorithm can be enhanced by extending it for multiple

*Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada* 

proposed algorithm can be improved by controlling the carrier sensing range. The phenomenon of topology control based on power control impacts the per-node fairness of medium access based on CSMA/CA and hence the per-flow end-to-end throughput fairness [34]. The proposed algorithm can be extended to ensure per-node

and hence per-flow fairness.

Aizaz U. Chaudhry and Roshdy H.M. Hafez

**List of acronyms and abbreviations** 

CAA Channel Assignment Algorithm

CCA Common Channel Assignment

CRT Controlled Random Topology

AODV Ad hoc On-Demand Distance Vector

BFS-CA Breadth First Search – Channel Assignment

CARM Channel Assignment and Routing Message

CSMA/CA Carrier Sense Multiple Access with Collision Avoidance

gateways.

**Author details** 

AP Access Point

AT Average Throughput

CA Channel Assignment

CBR Constant Bit Rate

C-HYA Centralized Hyacinth

D-HYA Distributed Hyacinth DNT Direct Neighbor Table FNT Final Neighbor Table


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**Chapter 4** 

© 2012 Pollak and Wieser, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Channel Assignment Schemes** 

Stefan Pollak and Vladimir Wieser

http://dx.doi.org/10.5772/46100

them are non-overlapping (Fig.2).

**1. Introduction** 

Additional information is available at the end of the chapter

**Optimization for Multi-Interface** 

**Wireless Mesh Networks Based on Link Load** 

In recent years, wireless mesh networks (WMNs) were deployed as a type of next generation wireless broadband networks. WMNs provide wireless broadband accessibility to extend the Internet connectivity to the last mile and improve the network coverage. WMN consists of a set of mesh routers and mesh clients (Fig. 1). *Mesh routers* are usually stationary and form multi-hop wireless backbone network (i.e. mesh routers are interconnected with each other via wireless medium). Some or all of the mesh routers also serve as access points for mobile users (*mesh clients*) under their coverage. Usually one or more mesh routers have direct connections to wired network and serve as Internet gateways for the rest of the network. These nodes are called *mesh gateways*. Compared to traditional wireless LANs, the main

feature of WMNs is their multi-hop wireless backbone capability (Conti et al., 2007).

Traditionally, wireless networks are equipped with only one IEEE 802.11 radio interface. However, a single-interface inherently restricts the whole network by using only one single channel (Fig. 3a). In order to communicate successfully, two neighboring routers have to build a logical link which operates on a common channel. Due to that, all wireless nodes have to use only one radio interface, all logical links in network must use the same channel. If two neighboring links operate on the same channel and transfer data simultaneously, then they definitely interfere with each other. The network capacity and the performance may degrade significantly because of the interference (Gupta & Kumar, 2000). The key factor for reducing the effect of interference is the using of non-overlapping channels (standard IEEE 802.11b/g provides 3 and standard IEEE 802.11a up to 12 non-overlapping channels) (Ramachandran et al., 2006). In practice, IEEE 802.11b/g defines 11 communication channels (number of communication channels varies due to regulations of different countries) but only 3 of

[35] S. Lakshmanan, R. Sivakumar, and K. Sundaresan, "Multi-Gateway Association in Wireless Mesh Networks," *Ad Hoc Networks*, Vol. 7(3), pp. 622–637, May 2009.
