Design and implementation of high quality H.264 video streaming over wireless mesh networks

Wireless multimedia home servers are the next generation of home entertainment systems. From a single broadband connection entering a residence, the multimedia stream is transmitted to television headsets and other peripherals by using only wireless links. The provision of high quality time-critical multimedia services in indoor environment is very challenging due to high attenuation and multi-path fading caused by the walls and contention in the shared channel. In this thesis, we demonstrate that the newly proposed wireless standard on wireless mesh networks can help improve the coverage while supporting Quality of Service requirements of both multimedia and data users, when the video packets are given EDCA priorities based on their importance according to the new high definition video streaming standard H.264. We support our hypothesis by presenting test results gathered from both simulations and from a real implementation test bed, where we observe very low delay and very few packet losses in video stream and almost no loss in perceived video quality even in the presence of high contending neighboring data traffi

Efficient Security Protocols for Fast Handovers in Wireless Mesh Networks

Wireless mesh networks (WMNs) are gaining popularity as a flexible and inexpensive replacement for Ethernet-based infrastructures. As the use of mobile devices such as smart phones and tablets is becoming ubiquitous, mobile clients should be guaranteed uninterrupted connectivity and services as they move from one access point to another within a WMN or between networks. To that end, we propose a novel security framework that consists of a new architecture, trust models, and protocols to offer mobile clients seamless and fast handovers in WMNs. The framework provides a dynamic, flexible, resource-efficient, and secure platform for intra-network and inter-network handovers in order to support real-time mobile applications in WMNs. In particular, we propose solutions to the following problems: authentication, key management, and group key management. We propose (1) a suite of certificate-based authentication protocols that minimize the authentication delay during handovers from one access point to another within a network (intra-network authentication). (2) a suite of key distribution and authentication protocols that minimize the authentication delay during handovers from one network to another (inter-network authentication). (3) a new implementation of group key management at the data link layer in order to reduce the group key update latency from linear time (as currently done in IEEE 802.11 standards) to logarithmic time. This contributes towards minimizing the latency of the handover process for mobile members in a multicast or broadcast group

Integration of unidirectional technologies into wireless back-haul architecture

This thesis was submitted for the degree of Docter of Philosophy and awarded by Brunel University.Back-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, the EU FP7 project CARMEN has developed a cost-effective heterogeneous multi-radio wireless back-haul architecture, which may also leverage the native multicast capabilities of broadcast technologies such as DVB-T to off-load high-bandwidth broadcast content delivery. However, the integration of such unidirectional technologies into a packet-switched architecture requires careful considerations. The contribution of this thesis is the investigation, design and evaluation of protocols and mechanisms facilitating the integration of such unidirectional technologies into the wireless back-haul architecture so that they can be configured and utilized by the spectrum and capacity optimization modules. This integration mainly concerns the control plane and, in particular, the aspects related to resource and capability descriptions, neighborhood, link and Multi Protocol Label Switching (MPLS) Label-Switched Path (LSP) monitoring, unicast and multicast LSP signalling as well as topology forming and maintenance. During the course of this study we have analyzed the problem space, proposed solutions to the resulting research questions and evaluated our approach. Our results show that the now Unidirectional Technology (UDT)-aware architecture can readily consider Unidirectional Technologies (UDTs) to distribute, for example, broadcast content

IEEE 802.11s Mesh Deterministic Access : Design and analysis

IEEE 802.11s is a draft IEEE 802.11 amendment for mesh networking, defining how wireless devices can interconnect to create an ad-hoc network. It includes some mesh-specific optional MAC enhancements like Mesh Deterministic Access, Common Channel Framework, Intra-mesh Congestion Control and Power Management. Mesh Deterministic Access (MDA) is an access method that allows MPs to access the channel at selected times (called MDAOPs) with lower contention than would otherwise be possible. In this work we study Mesh Deterministic Access (MDA) feature. Specifically: we implement 802.11s in ns-2 simulator and evaluate performance comparing results with those obtained with DCF. We also propose an improvement called Dynamic Relocation. Dynamic Relocation permits to overcome MDA limits by reallocating MDAOPs basing on statistics collected during transmission times. The effectiveness of MDA improved with Dynamic Relocation in a scenario with realistic traffic is then confirmed via a simulation analysis

Improving the reliability of optimised link state routing in a smart grid neighbour area network based wireless mesh network using multiple metrics

© 2017 by the authors; licensee MDPI. Reliable communication is the backbone of advanced metering infrastructure (AMI). Within the AMI, the neighbourhood area network (NAN) transports a multitude of traffic, each with unique requirements. In order to deliver an acceptable level of reliability and latency, the underlying network, such as the wireless mesh network (WMN), must provide or guarantee the quality-of-service (QoS) level required by the respective application traffic. Existing WMN routing protocols, such as optimised link state routing (OLSR), typically utilise a single metric and do not consider the requirements of individual traffic; hence, packets are delivered on a best-effort basis. This paper presents a QoS-aware WMN routing technique that employs multiple metrics in OLSR optimal path selection for AMI applications. The problems arising from this approach are non deterministic polynomial time (NP)-complete in nature, which were solved through the combined use of the analytical hierarchy process (AHP) algorithm and pruning techniques. For smart meters transmitting Internet Protocol (IP) packets of varying sizes at different intervals, the proposed technique considers the constraints of NAN and the applications' traffic characteristics. The technique was developed by combining multiple OLSR path selection metrics with the AHP algorithm in ns-2. Compared with the conventional link metric in OLSR, the results show improvements of about 23% and 45% in latency and Packet Delivery Ratio (PDR), respectively, in a 25-node grid NAN

A Novel Packet Aggregation Mechanism for Enhancing VoIP Performance on IEEE 802.11 Wireless Mesh Networks

In 802.11 Wireless Mesh Network (WMN), bandwidth will be wasted much for transferring VoIP flows since each voice frame must contain relatively large amount of protocol data. “Packet Aggregation” mechanism can be applied to merge the voice data of multiple VoIP flows into one frame for transmission. It reduces the waste on bandwidth and increases the maximum number of successful VoIP calls. In addition, the mechanism “MCF controlled channel access” (MCCA) defined in 802.11 standard can be used to obtain better QoS than adopting default EDCA mechanism. In MCCA, mesh stations which wants to transfer VoIP flows can reserve time intervals of the medium for transmission and this reservation will be advertised to their neighbors. It is why MCCA causes less medium contentions than EDCA. In this paper, a mechanism to transfer VoIP flows in IEEE 802.11 WMN by MCCA with packet aggregation scheme is proposed. The effectiveness of the proposed mechanism is shown by simulation results. In addition, the problem named as Routing-Packet Aggregation / De-aggregation-Scheduling optimization problem (abbr. RPADS problem) derived from the proposed mechanism is also studied. A heuristic algorithm for RPADS problem to maximize the total number of supported calls is also proposed

Towards QoS provisioning in a heterogeneous carrier-grade wireless mesh access networks using unidirectional overlay cells

Proceedings of: 6th International ICST Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, QShine 2009 and 3rd International Workshop on Advanced Architectures and Algorithms for Internet Delivery and Applications, AAA-IDEA 2009, Las Palmas, Gran Canaria, November 23-25, 2009The visibility and success ofWireless Mesh Network (WMN) deployments has raised interest among commercial operators in this technology. Compared to traditional operator access networks WMNs have the potential to offer easier deployment and flexible self-reconfiguration at lower costs. A WMN-type architecture considered as an alternative for an operator access network must meet similar requirements such as high availability and guaranteed QoS in order to support triple-play content provisioning. In this paper we introduce an architecture of such a Carrier-grade Wireless Mesh Access Network (CG-WMAN). We then present our contribution, an approach to seamlessly integrate unidirectional broadcast cells (i.e. DVB-T) into such a CG-WMAN. This allows higher layer protocols to utilize broadcast cells like regular mesh links, where beneficial for a given payload and receiver distribution. We then present a typical use case and discuss for which combinations of traffic type, user distribution and QoS requirements the use of longer range broadcast technologies can help to improve the overall CG-WMAN performance in terms of throughput and reliability.European Community's Seventh Framework ProgramPublicad

Topology forming and optimization framework for heterogeneous wireless back-haul networks supporting unidirectional technologies

Wireless operators, in developed or emerging regions, must support triple-play service offerings as demanded by the market or mandated by regulatory bodies through so-called Universal Service Obligations (USOs). Since individual operators might face different constraints such as available spectrum licenses, technologies, cost structures or a low energy footprint, the EU FP7 CARrier grade wireless MEsh Network (CARMEN) project has developed a carrier-grade heterogeneous multi-radio back-haul architecture which may be deployed to extend, complement or even replace traditional operator equipment. To support offloading of live triple-play content to broadcast-optimized, e.g., DVB-T, overlay cells, this heterogeneous wireless back-haul architecture integrates unidirectional broadcast technologies. In order to manage the physical and logical resources of such a network, a centralized coordinator approach has been chosen, where no routing state is kept at plain WiBACK Nodes (WNs) which merely store QoS-aware MPLS forwarding state. In this paper we present our Unidirectional Technology (UDT)-aware design of the centralized Topology Management Function (TMF), which provides a framework for different topology and spectrum allocation optimization strategies and algorithms to be implemented. Following the validation of the design, we present evaluation results using a hybrid local/centralized topology optimizer showing that our TMF design supports the reliable forming of optimized topologies as well as the timely recovery from node failures.Federal Ministry of Education and Research of the Federal Republic of German (F¨orderkennzeichen 01 BU1116,SolarMesh Energieeffizientes,autonomesgroßfl¨achiges Sprach- undDatenfunknetzmitflacher IP-Architektur