In the world of wireless communication technologies, the new standard IEEE 802.11n (MIMO) has revolutionized the available wireless bandwidth. Significant industrial and academic research has been initiated on this new technology around the world. Moreover, international as well as local manufacturers are highly interested in commercialization and performance improvement of this new technology. This is a research project in which we will perform comprehensive benchmarking of IEEE 802.11n in wireless multi-hop environments. In this project we evaluate the performance of routing metrics: Hop Count (HC) and Expected Transmission Count (ETX) on a test bed at A-Block Air University.
Top1. Introduction
Today, the Internet plays a vital role in providing connectivity-related services to people all around the world. Wireless Local Area Networks (WLANs) provide one of the fundamental blocks of the integration of the wireless devices to the wired Internet. Traditionally, WLANs provide us a centralized control and assume wired connectivity between the Access Points. However, with the new technologies, the concept of wireless multi-hop networks was introduced in order to have more flexible and practical deployments in remote and harsh environments. Wireless Multi-hop Networks (WMNs) are formed by using independent wireless or mobile nodes which interconnect wirelessly to create a wireless multihop backbone. However, more recently, Wireless Multihop Networks such as community mesh networks have become immensely popular all around the world and can play a significant role in providing high-speed last-mile wireless Internet broadband to users spread over large geographical regions (Broch, 1998). Therefore, wireless multihop networks will also have a major role in facilitating the proliferation of the cloud computing to end users in the coming years. As leaps and bounds are achieve in advancing the state of the art of cloud computing, the last-mile connectivity of end users will play an increasingly important role in the overall benefits reaped by the community.
Wireless technologies have also significantly improved during the last decade and wireless multihop networks such as wireless mesh networks have become significantly important. A wireless technology that has played an important role in pushing the bandwidth limits of wireless communication is the IEEE 802.11n commonly known an MIMO (Multiple-Input-Multiple-Output).
Routing protocols for wireless networks have been extensively researched during the recent years and significant research has been done in optimizing these protocols. Another important factor in the performance of these routing protocols is the routing metric which is being used. The routing metric is basically the performance metric which the routing protocols consider the most important and they select end-to-end routes between devices based on this metric. In this chapter, we will study the performance of contemporary routing metrics on a wireless test-bed and see their performance. The following are the objectives of this chapter:
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To study the performance of wireless multi hop network in a real test-bed environment.
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To study the performance of different metrics like Hop Count and Expected Transmission Time (ETX) on Dual Band Radio (2.4ghz, 5ghz).
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To analyze the performance of metrics and radio (throughput, packet loss and latency).
Top2. Background
Although the optical fiber has large advantages in bandwidth and transmission loss, the cost of installation and maintenance, especially for rural areas, limit their application to access network services. Most 802.11 WLAN networks today are bridged by using wired technology i.e., Access Points are connected with each other through physical links (typically Ethernet). The dependency on wired network should be removed because of the following reasons:
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This dependency results in inflexibility as it becomes infeasible to extend the coverage of the WLAN beyond the deployment of the backbone wired network.
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Due to their design, centralized structures such as WLANs do not work efficiently for contemporary applications including wireless games which require a different type of connectivity such as peer-to-peer.
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A fixed topology disables the selection of more efficient paths across the network.
Next, the demand that comes from having the ability to communicate wherever and whenever has led to an inevitable trend in wireless access. Thus, the multi-hop wireless network (WMN) have been created with the additional WLAN access points are connected through Internet gateways wire wireless links to other access points using decentralized architectures. WMN hold the promise of overcoming emerging needs and promises to provide seamless last-mile wireless connectivity to users.