PhD, University of Cincinnati, 2009, Engineering : Computer Science and Engineering

Wireless Mesh Networks (WMNs) are one of the upcoming technologies which envision providing broadband internet access to users any where any time. WMNs comprise of Internet Gateways (IGWs) and Mesh Routers (MRs). They seamlessly extend the network connectivity to Mesh Clients (MCs) as end users by forming a wireless backbone that requires minimal infrastructure. For WMNs, frequent link quality fluctuations, excessive load on selective links, congestion, and limited capacity due to half-duplex nature of radios are some key limiting factors that hinder their deployment. Also, other problems such as unfair channel access, improper buffer management, and irrational routing choices are impeding the successful large scale deployment of mesh networks. Quality of Service (QoS) provisioning and scalability in terms of supporting large number of users with decent bandwidth are other important issues.In this dissertation, we examine some of the aforementioned problems in WMNs and propose novel algorithms to solve them. We find that the proposed solutions enhance the network's performance significantly. In particular, we provide a traffic differentiation methodology, Dual Queue Service Differentiation (DQSD), which helps in fair throughput distribution of network traffic regardless of spatial location of its nodes. We next focus on managing the IGWs in WMNs since they are the potential bottleneck candidates due to huge volume of traffic that has to flow through them. To address this issue, we propose a load balancing protocol, LoaD BALancing (LDBAL), which efficiently distributes the traffic load among a given set of IGWs. We then delve into the aspects of load balancing and traffic distribution over multiple traffic paths in WMNs. To achieve this, we propose a novel Adaptive State-based Multipath Routing Protocol (ASMRP) that provides reliable and robust performance in WMNs. We also employ four-radio architecture for MRs, which allows them to communicate over multiple radios t (open full item for complete abstract)

Committee: Dharma Agrawal DSc (Committee Chair); Kenneth Berman PhD (Committee Member); Yiming Hu PhD (Committee Member); Kelly Cohen PhD (Committee Member); Chia Han PhD (Committee Member) Subjects: Computer Science

PhD, University of Cincinnati, 2007, Engineering : Computer Science and Engineering

Recent years have witnessed an extensive proliferation of wireless technology in every domain of day-to-day life. Examples include mobile phones, broadband communication, wireless LAN, wireless enabled PDAs, cordless phones, garage-door openers and the list continues. Advancements in radio technology, antenna technology, low power computational digital signal processing (DSP) and micro-electro-mechanical systems (MEMS) are instrumental in reducing the size and cost of wireless devices. A wireless network consists of wireless devices forming an infrastructure-based or a peer-to-peer network. A network can be a single-hop or multihop network. Single-hop networks are already in existence and have been substantially investigated. This dissertation thus focuses on multihop wrireless networks, where the intermediate wireless devices also act as routers. Depending on their functionality, multihop wireless networks can be categorized into ad hoc, mesh and sensor networks. A mobile ad hoc network (MANET) aims at provding a mobile network with connectivity similar to a wired network without the need for any infrastructure support. A wireless mesh network (WMN) typically extends the infrastructure based single hop wireless network and has become a new paradigm for providing last mile broadband access. A wireless sensor network (WSN) is similar to an ad hoc network, providing a cheap alternative to monitoring applications. Each of these multihop wireless networks has their own set of challenges with respect to operation and implementation. The first part of this dissertation focuses on developing on-demand medium access control (MAC) protocols for multiple beam smart antennas (MBSAs) in ad hoc and mesh environments. MBSA has the unique capability of simultaneously initiating packet transmissions or receptions in multiple beams. Thus, compared to traditional omnidirectional antennas, MBSA can better utilize the spatial bandwidth, thereby increasing the capacity of wireless netwo (open full item for complete abstract)

Committee: Dr. Dharma Agrawal (Advisor) Subjects: Computer Science