**Author details**

Fawaz Bokhari and Gergely Záruba *Department of Computer Science and Engineering, The University of Texas at Arlington, Texas, USA* 

#### **7. References**

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

Multiradio Support

A. Mishra [5] Centralized No ACI No Dynamic No MICA [10] Centralized No ACI No Fixed Yes CAEPO [12] Distributed No ACI Yes Hybrid Yes Load-Aware CAEPO-G [13] Distributed Yes ACI Yes Hybrid Yes M. Hoque [19] Centralized Yes ACI and SI No Dynamic No P. Duarte [20] Centralized Yes ACI, SI and CCI No Dynamic Yes A. Rad [18] Centralized Yes ACI and CCI Joint Fixed Yes V. Bukkapatanam [15] Centralized Yes ACI Joint Fixed Yes POCAM [16] Centralized Yes ACI and SI No Hybrid Yes Y. Ding [7] Centralized No ACI No Dynamic No A. Subramanian [17] Both Yes ACI No Dynamic Yes **Table 8.** Summary of characteristics of all POCA approaches in wireless mesh networks.

In this chapter, we have discussed the problem of assigning channels with partial overlaps to radios in single- and multi-radio WMNs. We have characterized different types of interferences that may exist in a WMN depending on the flow characteristics and on the particular configuration of interfaces to channel assignments. We then presented IEEE 802.11 standard constraints on communications and evaluated the benefits of using partially overlapped channels (POCs) for the design of efficient channel assignment schemes with the help of experiments performed on a real testbed. Our, and previous experiments demonstrated that the use of POCs: i) improves network capacity by enabling more parallel communications and ii) provides more efficient utilization of the available spectrum. We have also provided a survey of some of the existing POC assignment schemes in WMNs and have classified them based on the interference models that they employ. Finally, we discussed some of the challenges and open issues in designing efficient channel assignment schemes

*Department of Computer Science and Engineering, The University of Texas at Arlington, Texas, USA* 

utilizing both orthogonal and non-orthogonal channels in WMNs.

To the best of our knowledge, there is no partially overlapping channel assignment algorithm that has been proposed to explore the multi-rate capability of IEEE 802.11 based hardware in MRMC-WMNs. Almost all the aforementioned works have assumed a fixed transmission rate (homogeneous links) which make the problem of channel assignment simple, whereas a POCA scheme with adaptive rates could potentially achieve significantly better performance.

Interference

Routing Dependenc Channel Switching Frequency

Focus on Connectivity

y

**5.4. Multi-rate capability** 

Characteristics Implementation

**6. Conclusions** 

**Author details** 

Fawaz Bokhari and Gergely Záruba

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**Section 2** 

**Network Planning Aspects in WMNs** 


http://dx.doi.org/10.1109/IEEESTD.2007.373646


**Network Planning Aspects in WMNs** 

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**Chapter 0**

**Chapter 6**

**Autonomous Traffic Balancing Routing**

Wireless mesh networks (WMNs) are attractively deployed as a backhaul for public Internet access with the advantages of network performance and cost efficiency. With the cooperation of multiple mesh nodes, a packet is transmitted through multi-hops to reach a destination. Wireless medium experiences relatively an unstable environment due to interferences of wireless signals. As traffic increases, a communication environment becomes worse. Similarly, as more mesh nodes join a WMN, a network performance is also degraded due to increasing interferences. Therefore, challenges of a WMN are how to accommodate a dynamic nature of

A typical WMN serves hub-and-spoke type accesses, where a mesh gateway (hub) connects to the Internet for mesh clients as shown in Fig. 1. In other words, a mesh node is required to communicate with just one-of-many mesh gateways similar to anycast communications [1, 2]. For anycasting, conventional routing schemes [3–5] are developed with modifications of existing unicast routing protocols. That is, the schemes usually select the closest destination among multiple service gateways. Thus, they are inefficient in taking benefits of having multiple gateways. Even though some protocols [6–8] utilize multiple gateways for load balancing, they convey flooding overheads to collect traffic load information for re-routing

Classically, back-pressure routing [9] and geographic routing [10] are considered as alternatives for traditional hop-count-based routing. Back-pressure routing is well-known to achieve throughput-optimal by adaptively selecting paths depending on queuing-dynamics. However, it unnecessarily chooses long paths and degrades network performance by keeping old data packets. This problem manifests critically in lightly- or moderately-loaded cases [11]. On the other hand, conventional geographic routing is scalable with no flooding overhead, but it is vulnerable to avoiding congested hot spots due to its simple geographical routing metric. Even though some enhancements of geographic routing for congestion mitigation, it

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

©2012 Jung, 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.

© 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,

entails similar overheads such as perimeter routing or other face routing.

**in Wireless Mesh Networks**

Additional information is available at the end of the chapter

wireless medium and achieve the scalability.

and require associations among the gateways.

Sangsu Jung

**1. Introduction**

http://dx.doi.org/10.5772/48540
