Cross Layer Network Architecture For Efficient Packet Forwarding In Wireless Networks

With the evolution of 802.11-based wireless networks from hotspots to mesh networks, there has been a tremendous increase in the number of wireless users and density of deployments. Consequently, current wireless network face several problems due to interference, uncoordinated medium access, packet processing overheads at each hop and sub-optimal route selection. While radio technologies continue to improve speeds upto hundred megabits per second, the inadequacies of medium access and routing protocols severely impact the overall network capacity and end-user experience. In this thesis, we focus on improving the scalability and packet forwarding efficiency of multihop wireless networks. We introduce a self-organizing hierarchical ad-hoc network design (SOHAN) based on a three-tier hierarchy with dedicated forwarding nodes to address the scalability of existing multihop networks. We focus on realistic system design considerations and develop a Linux-based system prototype including novel protocols for bootstrapping, discovery and topology control to enable hierarchical self-organization. Experimental and simulation-based evaluations indicate a 2.5 times performance improvement over flat network models. We address packet forwarding inefficiencies of existing techniques over multihop networks due to queuing, contention and reprocessing at each hop and propose an interface contained forwarding architecture (ICF) using a combination of cut-through MAC protocol and label-based forwarding to enable "atomic" channel access for downstream transmissions and reduce self-interference. Next, we design a cross layer enabled cut through architecture (CLEAR) that extends the ICF mechanism with novel airtime metric-based route selection to mitigate the interference between flows. We further outline a time-based coordination scheme using soft reservations during route discovery phase to coordinate multihop "burst" transfers amongst flows. This model can be adapted to support differentiated services and provide a"low-latency socket" for real-time traffic over multiple hops. Our work can be the basis for a switched multihop wireless network design that enables conflict-free transfers resulting in efficient utilization of channel capacity and providing a viable alternative to wired network deployments. A substantial contribution of this thesis also includes the design and development of the ORBIT wireless testbed with focus on cross-layer experimental framework to facilitate rapid prototyping of wireless protocols and experimental evaluations at scale.

Doctoral Thesis / Dissertation from the year 2016 in the subject Computer Science - Miscellaneous, grade: 16, , language: English, abstract: In this thesis, we have modified AODV routing protocol by incorporating link prediction algorithm using a proposed link prediction model. This algorithm predicts the link availability time and even before the link breaks; either it repairs the route locally or sends information to the source nodes to enable them to initiate a new route search well in time. This algorithm improves the quality of service of the network. Simulation results show that AODV routing algorithm with link availability model performs better than the existing AODV. Advances in wireless technology and hand-held computing devices have brought revolution in the area of mobile communication. The increasing mobility of humans across the globe generated demand for infrastructure-less and quickly deployable mobile networks. Such networks are referred to as Mobile Adhoc Networks (MANET). Usually, nodes in a MANET also act as a router while being is free to roam while communicating each others. Adhoc networks are suited for use in situations where infrastructure is unavailable or to deploy one is not cost-effective. Frequent changes in network topology due to mobility and limited battery power of the mobile devices are the key challenges in the adhoc networks. The depletion of power source may cause early unavailability of nodes and thus links in the network. The mobility of nodes will also causes frequent routes breaks and adversely affects the required performance for the applications. Availability of a route in future mainly depends on the availability of links between the nodes forming the route. Therefore, it is important to predict the future availability of a link that is currently available. We have proposed an analytical model for link prediction using Newton divided difference method. This link availability algorithm is incorporated in AODV routing algorithm (AODVLP) to evaluate the performance of AODV routing protocol using the metrics viz. delivery rate, average end-to-end delay, average RTS collisions per node and route failure. In the existing AODV protocol, packets are routed until a link in the existing path fails. This results in degradation of quality of service of network in terms of end-to-end delay and delivery ratio.

The layered architecture based on OSI model has been widely used in wired networks. Due to the dynamics of wireless medium and the node mobility, many special problems appear in wireless networks, which prevent the conventional layered architecture from functioning optimally in wireless environment. In this thesis, we study the wireless networks from different perspectives. Our objective is to systematically develop network protocols and architecture to address various limitations of wireless systems by assuming a cross-layer approach. Firstly, we develop an energy consumption model for wireless ad hoc networks. In existing work, transmission power is commonly used to represent energy consumption cost. In this study, we analyze possible energy consumptions in physical layer, MAC layer (such as signaling packets), and upper layers (such as end-to-end retransmission), and propose more accurate models to capture the energy consumption cost due to different factors. Secondly, based on the energy consumption model, we design an energy efficient routing protocol. The existing energy efficient routing protocols only focus on the search of the most energy efficient path. However, there are many problems in these protocols, including broadcast storm issue, long setup delay, and poor performance in mobility scenario. In this study, we propose an efficient method for estimating the accurate link cost, a quick path searching scheme to find the energy efficient path, and an efficient maintenance scheme to adjust the path according to the environment. Thirdly, we perform the cross-layer design for multiple-channel multiple-interface network to improve the throughput. Current MAC and routing protocols are mainly developed for only one channel and the existing wireless devices are equipped with only one wireless interface. In this study, we design a unified MAC and routing framework to exploit the benefits enabled by the multiple channels to improve the capacity of ad hoc networks. Our joint channel assignment and routing scheme searches for an efficient transmission path, while taking into account the limited number of channels/interfaces, local topology information, and link rate diversity. Our scheduling scheme at MAC layer coordinates transmissions within the vicinity over a short time scale to maximize channel usage and avoid collision among nodes sharing the same channel. The scheduling scheme complemented with prioritized transmitting will also coordinate interface switching to avoid unnecessary switching delay, support load balancing, reduce the broadcast delay and further improve throughput in a multi-channel multi-interface environment.

Adaptive techniques play a key role in modern wireless communication systems. The concept of adaptation is emphasized in the Adaptation in Wireless Communications Series through a unified framework across all layers of the wireless protocol stack ranging from the physical layer to the application layer, and from cellular systems to next-generation wireless networks. Adaptation and Cross Layer Design in Wireless Networks is devoted to adaptation in the data link layer, network layer, and application layer. The book presents state-of-the-art adaptation techniques and methodologies, including cross-layer adaptation, joint signal processing, coding and networking, selfishness in mobile ad hoc networks, cooperative and opportunistic protocols, adaptation techniques for multimedia support, self –organizing routing, and tunable security services. It presents several new theoretical paradigms and analytical findings which are supported with various simulation and experimental results. Adaptation in wireless communications is needed in order to achieve high capacity and ubiquitous communications. The current trend in wireless communication systems is to make adaptation dependent upon the state of the relevant parameters in all layers of the system. Focusing on simplified cross layer design approaches, this volume describes advanced techniques such as adaptive resource management, adaptive modulation and coding, 4G communications, QoS, diversity combining, and energy and mobility aware MAC protocols. The first volume in the series, Adaptive Signal Processing in Wireless Communications (cat no.46012) covers adaptive signal processing at the physical layer.

Although the existing layering infrastructure--used globally for designing computers, data networks, and intelligent distributed systems and which connects various local and global communication services--is conceptually correct and pedagogically elegant, it is now well over 30 years old has started create a serious bottleneck. Using Cross-Layer Techniques for Communication Systems: Techniques and Applications explores how cross-layer methods provide ways to escape from the current communications model and overcome the challenges imposed by restrictive boundaries between layers. Written exclusively by well-established researchers, experts, and professional engineers, the book will present basic concepts, address different approaches for solving the cross-layer problem, investigate recent developments in cross-layer problems and solutions, and present the latest applications of the cross-layer in a variety of systems and networks.

This book provides a systematic introduction to the fundamental concepts, major challenges, and effective solutions for Quality of Service in Wireless Sensor Networks (WSNs). Unlike other books on the topic, it focuses on the networking aspects of WSNs, discussing the most important networking issues, including network architecture design, medium access control, routing and data dissemination, node clustering, node localization, query processing, data aggregation, transport and quality of service, time synchronization, and network security. Featuring contributions from researchers, this book strikes a balance between fundamental concepts and new technologies, providing readers with unprecedented insights into WSNs from a networking perspective. It is essential reading for a broad audience, including academics, research engineers, and practitioners, particularly postgraduate/postdoctoral researchers and engineers in industry. It is also suitable as a textbook or supplementary reading for graduate computer engineering and computer science courses.

An important challenge in the design of wireless and mobile systems is that two key resources - communication bandwidth and energy - are significantly more limited than in a tethered network environment. In addition, the time-varying characteristics of wireless channels make it hard to consistently obtain the same performance. These restrictions require innovative communication, networking, and design techniques for the efficient utilization of the bandwidth and energy. One of the most rapidly developing areas in wireless networks is wireless ad hoc networks. A wireless ad hoc network is an autonomous system consisting of nodes, which may or may not be mobile, connected with wireless links and without using pre-existing communication infrastructure or central control. Ad hoc networking is expected to play an important role in future wireless mobile networks due to the widespread use of mobile and hand-held devices. Mobile Ad hoc Networks (MANETs) and Wireless Sensor Networks (WSNs) are two prominent classes of these infrastructureless wireless networks. While MANETs exhibit dynamic topology changes due to free node mobility, WSNs have unreplenishible energy limitations. Hence, topology control, Quality of Service (QoS) routing, and power control become challenging issues. We argue that cluster-based techniques coupled with cross-layer design can achieve better performance in this harsh environment. This dissertation supports this claim by introducing strategies for topology control, QoS routing in MANETs, and energy efficient routing in WSNs. First, we develop the Virtual Grid Architecture (VGA), which is a fixed and stable architecture for ad hoc networks that can support efficient routing and network control. We show that although VGA clustering is simple, it is close to optimal. Then, we develop two QoS routing protocols that combine the ideas of cluster-based routing and cross layer design to achieve good performance in terms of delay, bandwidth, and user-perceived quality. These protocols, operating on top of VGA, show improved system call success rate and packet delivery ratio by an order of magnitude compared to general-purpose approaches. Finally, we develop GRASP (Grid-based Routing and Aggregator Selection Protocols), a scheme for WSNs which combines the ideas of fixed cluster-based routing of VGA together with application-specific data aggregation functions. GRASP is able to enhance the network performance in terms of extending the network lifetime, while incurring acceptable levels of latency in data aggregation. Our studies together show that creating stable and scalable architecture can achieve topology robustness, enhance quality of service, and attain the energy and latency efficiency needed for wireless networks.

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"This book focuses on wireless sensor networks and their operation, covering topics including routing, energy efficiency and management"--

Information flow in a telecommunication network is accomplished through the interaction of mechanisms at various design layers with the end goal of supporting the information exchange needs of the applications. In wireless networks in particular, the different layers interact in a nontrivial manner in order to support information transfer. In this text we will present abstract models that capture the cross-layer interaction from the physical to transport layer in wireless network architectures including cellular, ad-hoc and sensor networks as well as hybrid wireless-wireline. The model allows for arbitrary network topologies as well as traffic forwarding modes, including datagrams and virtual circuits. Furthermore the time varying nature of a wireless network, due either to fading channels or to changing connectivity due to mobility, is adequately captured in our model to allow for state dependent network control policies. Quantitative performance measures that capture the quality of service requirements in these systems depending on the supported applications are discussed, including throughput maximization, energy consumption minimization, rate utility function maximization as well as general performance functionals. Cross-layer control algorithms with optimal or suboptimal performance with respect to the above measures are presented and analyzed. A detailed exposition of the related analysis and design techniques is provided.