WiMAX-WiFi techniques for baseband convergence and routing protocols

The focus of this study was to investigate solutions that, when implemented in any heterogeneous wireless network, shall enhance the existing standard and routing protocol connectivity without impacting the standard or changing the wireless transceiver’s functions. Thus achieving efficient interoperability at much reduced overheads. The techniques proposed in this research are centred on the lower layers. This because of the facts that WiMax and WiFi standards have not addressed the backward compatibility of the two technologies at the MAC and PHY layers, for both the baseband functions as well as the routing IP addresses. This thesis describes two innovate techniques submitted for a PhD degree. The first technique is to combine WiMax and WiFi signals so to utilise the same "baseband implementation chain" to handle both of these technologies, thus insuring ubiquitous data communication. WiMax-WiFi Baseband Convergence (W2BC) implementation is proposed to offer an optimum configurable solution targeted at combining the 802.16d WiMax and the 802.11a WiFi technologies. This approach provides a fertile ground for future work into combining more OFDM based wireless technologies. Based on analysis and simulation, the W2BC can achieve saving in device cost, size, power consumption and implementation complexity when compared to current side-by-side implementations for these two technologies. The second technique, called "Prime-IP", can be implemented with, and enhance, any routing protocol. During the route discovery process, Prime-IP enables any node on a wireless mesh network (WMN) to dynamically select the best available route on the network. Prime-IP proposes a novel recursive process, based on prime numbers addressing, to accumulate knowledge for nodes beyond the “neighbouring nodes”, and to determine the sequence of all the “intermediate nodes” used to form the rout

Application-aware scheduling for VoIP in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) are seen as a means to provide last mile connections in Next Generation Networks (NGNs). Because of their auto configuration capabilities and the low deployment cost WMNs are considered to be an efficient solution for the support of multiple voice, video and data services in NGNs. This paper looks at the optimal provision of resources in WMNs for Voice over IP (VoIP) traffic, which has strict performance requirements in terms of delay, jitter and packet loss. In WMNs, because of the challenges introduced by wireless multi hop transmissions and limited resources, providing performance quality for VoIP comparable to the voice quality in the traditional circuit switched networks is a major challenge. This paper analyses different scheduling mechanisms for TDMA based access control in mesh networks as specified in the IEEE 802.16 2004 WiMAX standard. The performance of the VoIP applications when different scheduling mechanisms are deployed is analysed on a variety of topologies using ns 2 simulation and mathematical analysis. The paper concludes that on demand scheduling of VoIP traffic typically deployed in 802.11 based WMNs is not able to provide the required VoIP quality in realistic mesh WiMAX network scenarios and is therefore not optimal from a network operator’s point of view. Instead, it is shown, that continuous scheduling is much better suited to serve VoIP traffic. The paper then proposes a new VoIP aware resource coordination scheme and shows, through simulation, that the new scheme is scalable and provides good quality for VoIP service in a wide range of network scenarios. The results shown in the paper prove that the new scheme is resilient to increasing hop count, increasing number of simultaneous VoIP sessions and the background traffic load in the network. Compared to other resource coordination schemes the VoIP aware scheduler significantly increases the number of supported calls

Application priority framework for fixed mobile converged communication networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence in order to offer integrated broadband services. These systems will need to offer higher data transmission capacities and long battery life, which is the catalyst for an everincreasing variety of air interface technologies targeting local area to wide area connectivity. Current integrated industrial networks do not offer application aware context delivery and enhanced services for optimised networks. Application aware services provide value-added functionality to business applications by capturing, integrating, and consolidating intelligence about users and their endpoint devices from various points in the network. This thesis mainly intends to resolve the issues related to ubiquitous application aware service, fair allocation of radio access, reduced energy consumption and improved capacity. A technique that measures and evaluates the data rate demand to reduce application response time and queuing delay for multi radio interfaces is proposed. The technique overcomes the challenges of network integration, requiring no user intervention, saving battery life and selecting the radio access connection for the application requested by the end user. This study is split in two parts. The first contribution identifies some constraints of the services towards the application layer in terms of e.g. data rate and signal strength. The objectives are achieved by application controlled handover (ACH) mechanism in order to maintain acceptable data rate for real-time application services. It also looks into the impact of the radio link on the application and identifies elements and parameters like wireless link quality and handover that will influence the application type. It also identifies some enhanced traditional mechanisms such as distance controlled multihop and mesh topology required in order to support energy efficient multimedia applications. The second contribution unfolds an intelligent application priority assignment mechanism (IAPAM) for medical applications using wireless sensor networks. IAPAM proposes and evaluates a technique based on prioritising multiple virtual queues for the critical nature of medical data to improve instant transmission. Various mobility patterns (directed, controlled and random waypoint) has been investigated and compared by simulating IAPAM enabled mobile BWSN. The following topics have been studied, modelled, simulated and discussed in this thesis: 1. Application Controlled Handover (ACH) for multi radios over fibre 2. Power Controlled Scheme for mesh multi radios over fibre using ACH 3. IAPAM for Biomedical Wireless Sensor Networks (BWSN) and impact of mobility over IAPAM enabled BWSN. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in multi radios over fibre performance in terms of application response delay and power consumption by upto 75% and 15 % respectively, reduction in traffic loss by upto 53% and reduction in delay for real time application by more than 25% in some cases

Mitigating hidden node problem in an IEEE 802.16 failure resilient multi-hop wireless backhaul

Backhaul networks are used to interconnect access points and further connect them to gateway nodes which are located in regional or metropolitan centres. Conventionally, these backhaul networks are established using metallic cables, optical fibres, microwave or satellite links. With the proliferation of wireless technologies, multi-hop wireless backhaul networks emerge as a potential cost effective and flexible solution to provide extended coverage to areas where the deployment of wired backhaul is difficult or cost-prohibitive, such as the difficult to access and sparsely populated remote areas, which have little or no existing wired infrastructure.Nevertheless, wireless backhaul networks are vulnerable to node or link failures. In order to ensure undisrupted traffic transmission even in the presence of failures, additional nodes and links are introduced to create alternative paths between each source and destination pair. Moreover, the deployment of such extra links and nodes requires careful planning to ensure that available network resources can be fully utilised, while still achieving the specified failure resilience with minimum infrastructure establishment cost.The majority of the current research efforts focus on improving the failure resilience of wired backhaul networks but little is carried out on the wireless counterparts. Most of the existing studies on improving the failure resilience of wireless backhaul networks concern energy-constrained networks such as the wireless sensor and ad hoc networks. Moreover, they tend to focus on maintaining the connectivity of the networks during failure, but neglecting the network performance. As such, it calls for a better approach to design a wireless backhaul network, which can meet the specified failure resilience requirement with minimum network cost, while achieving the specified quality of service (QoS).In this study, a failure resilient wireless backhaul topology, taking the form of a ladder network, is proposed to connect a remote community to a gateway node located in a regional or metropolitan centre. This topology is designed with the use of a minimum number of nodes. Also, it provides at least one backup path between each node pair. With the exception of a few failure scenarios, the proposed ladder network can sustain multiple simultaneous link or node failures. Furthermore, it allows traffic to traverse a minimum number of additional hops to arrive at the destination during failure conditions.WiMax wireless technology, based on the IEEE 802.16 standard, is applied to the proposed ladder network of different hop counts. This wireless technology can operate in either point-to-multipoint single-hop mode or multi-hop mesh mode. For the latter, coordinated distributed scheduling involving a three-way handshake procedure is used for resource allocation. Computer simulations are used to extensively evaluate the performance of the ladder network. It is shown that the three-way handshake suffers from severe hidden node problem, which restrains nodes from data transmission for long period of time. As a result, data packets accumulate in the buffer queue of the affected nodes and these packets will be dropped when the buffer overflows. This in turn results in the degradation of the network throughput and increase of average transmission delay.A new scheme called reverse notification (RN) is proposed to overcome the hidden node problem. With this new scheme, all the nodes will be informed of the minislots requested by their neighbours. This will prevent the nodes from making the same request and increase the chance for the nodes to obtain all their requested resources, and start transmitting data as soon as the handshake is completed. Computer simulations have verified that the use of this RN can significantly reduce the hidden terminal problem and thus increase network throughput, as well as reduce transmission delay.In addition, two new schemes, namely request-resend and dynamic minislot allocation, are proposed to further mitigate the hidden node problem as it deteriorates during failure. The request-resend scheme is proposed to solve the hidden node problem when the RN message failed to arrive in time at the destined node to prevent it from sending a conflicting request. On the other hand, the dynamic minislot allocation scheme is proposed to allocate minislots to a given node according to the amount of traffic that it is currently servicing. It is shown that these two schemes can greatly enhance the network performance under both normal and failure conditions.The performance of the ladder network can be further improved by equipping each node with two transceivers to allow them to transmit concurrently on two different frequency channels. Moreover, a two-channel two-transceiver channel assignment (TTDCA) algorithm is proposed to allocate minislots to the nodes. When operating with this algorithm, a node uses only one of its two transceivers to transmit control messages during control subframe and both transceivers to transmit data packets during data subframe. Also, the frequency channels of the nodes are pre-assigned to more effectively overcome the hidden node problem. It is shown that the use of the TTDCA algorithm, in conjunction with the request-resend and RN schemes, is able to double the maximum achievable throughput of the ladder network, when compared to the single channel case. Also, the throughput remains constant regardless of the hop counts.The TTDCA algorithm is further modified to make use of the second transceiver at each node to transmit control messages during control subframe. Such an approach is referred to as enhanced TTDCA (ETTDCA) algorithm. This algorithm is effective in reducing the duration needed to complete the three-way handshake without sacrificing network throughput. It is shown that the application of the ETTDCA algorithm in ladder networks of different hop counts has greatly reduced the transmission delay to a value which allows the proposed network to not only relay a large amount of data traffic but also delay-sensitive traffics. This suggests that the proposed ladder network is a cost effective solution, which can provide the necessary failure resilience and specified QoS, for delivering broadband multimedia services to the remote rural communities

Smart PIN: performance and cost-oriented context-aware personal information network

The next generation of networks will involve interconnection of heterogeneous individual networks such as WPAN, WLAN, WMAN and Cellular network, adopting the IP as common infrastructural protocol and providing virtually always-connected network. Furthermore, there are many devices which enable easy acquisition and storage of information as pictures, movies, emails, etc. Therefore, the information overload and divergent content’s characteristics make it difficult for users to handle their data in manual way. Consequently, there is a need for personalised automatic services which would enable data exchange across heterogeneous network and devices. To support these personalised services, user centric approaches for data delivery across the heterogeneous network are also required. In this context, this thesis proposes Smart PIN - a novel performance and cost-oriented context-aware Personal Information Network. Smart PIN's architecture is detailed including its network, service and management components. Within the service component, two novel schemes for efficient delivery of context and content data are proposed: Multimedia Data Replication Scheme (MDRS) and Quality-oriented Algorithm for Multiple-source Multimedia Delivery (QAMMD). MDRS supports efficient data accessibility among distributed devices using data replication which is based on a utility function and a minimum data set. QAMMD employs a buffer underflow avoidance scheme for streaming, which achieves high multimedia quality without content adaptation to network conditions. Simulation models for MDRS and QAMMD were built which are based on various heterogeneous network scenarios. Additionally a multiple-source streaming based on QAMMS was implemented as a prototype and tested in an emulated network environment. Comparative tests show that MDRS and QAMMD perform significantly better than other approaches

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

New Waves of IoT Technologies Research – Transcending Intelligence and Senses at the Edge to Create Multi Experience Environments

The next wave of Internet of Things (IoT) and Industrial Internet of Things (IIoT) brings new technological developments that incorporate radical advances in Artificial Intelligence (AI), edge computing processing, new sensing capabilities, more security protection and autonomous functions accelerating progress towards the ability for IoT systems to self-develop, self-maintain and self-optimise. The emergence of hyper autonomous IoT applications with enhanced sensing, distributed intelligence, edge processing and connectivity, combined with human augmentation, has the potential to power the transformation and optimisation of industrial sectors and to change the innovation landscape. This chapter is reviewing the most recent advances in the next wave of the IoT by looking not only at the technology enabling the IoT but also at the platforms and smart data aspects that will bring intelligence, sustainability, dependability, autonomy, and will support human-centric solutions.acceptedVersio

Improving the Reliability of Optimised Link State Routing Protocol in Smart Grid’s Neighbour Area Network

A reliable and resilient communication infrastructure that can cope with variable application traffic types and delay objectives is one of the prerequisites that differentiates a Smart Grid from the conventional electrical grid. However, the legacy communication infrastructure in the existing electrical grid is insufficient, if not incapable of satisfying the diverse communication requirements of the Smart Grid. The IEEE 802.11 ad hoc Wireless Mesh Network (WMN) is re-emerging as one of the communication networks that can significantly extend the reach of Smart Grid to backend devices through the Advanced Metering Infrastructure (AMI). However, the unique characteristics of AMI application traffic in the Smart Grid poses some interesting challenges to conventional communication networks including the ad hoc WMN. Hence, there is a need to modify the conventional ad hoc WMN, to address the uncertainties that may exist in its applicability in a Smart Grid environment. This research carries out an in-depth study of the communication of Smart Grid application traffic types over ad hoc WMN deployed in the Neighbour Area Network (NAN). It begins by conducting a critical review of the application characteristics and traffic requirements of several Smart Grid applications and highlighting some key challenges. Based on the reviews, and assuming that the application traffic types use the internet protocol (IP) as a transport protocol, a number of Smart Grid application traffic profiles were developed. Through experimental and simulation studies, a performance evaluation of an ad hoc WMN using the Optimised Link State Routing (OLSR) routing protocol was carried out. This highlighted some capacity and reliability issues that routing AMI application traffic may face within a conventional ad hoc WMN in a Smart Grid NAN. Given the fact that conventional routing solutions do not consider the traffic requirements when making routing decisions, another key observation is the inability of link metrics in routing protocols to select good quality links across multiple hops to a destination and also provide Quality of Service (QoS) support for target application traffic. As with most routing protocols, OLSR protocol uses a single routing metric acquired at the network layer, which may not be able to accommodate different QoS requirements for application traffic in Smart Grid. To address these problems, a novel multiple link metrics approach to improve the reliability performance of routing in ad hoc WMN when deployed for Smart Grid is presented. It is based on the OLSR protocol and explores the possibility of applying QoS routing for application traffic types in NAN based ad hoc WMN. Though routing in multiple metrics has been identified as a complex problem, Multi-Criteria Decision Making (MCDM) techniques such as the Analytical Hierarchy Process (AHP) and pruning have been used to perform such routing on wired and wireless multimedia applications. The proposed multiple metrics OLSR with AHP is used to offer the best available route, based on a number of considered metric parameters. To accommodate the variable application traffic requirements, a study that allows application traffic to use the most appropriate routing metric is presented. The multiple metrics development is then evaluated in Network Simulator 2.34; the simulation results demonstrate that it outperforms existing routing methods that are based on single metrics in OLSR. It also shows that it can be used to improve the reliability of application traffic types, thereby overcoming some weaknesses of existing single metric routing across multiple hops in NAN. The IEEE 802.11g was used to compare and analyse the performance of OLSR and the IEEE 802.11b was used to implement the multiple metrics framework which demonstrate a better performance than the single metric. However, the multiple metrics can also be applied for routing on different IEEE wireless standards, as well as other communication technologies such as Power Line Communication (PLC) when deployed in Smart Grid NAN

Mathematical optimization techniques for demand management in smart grids

The electricity supply industry has been facing significant challenges in terms of meeting the projected demand for energy, environmental issues, security, reliability and integration of renewable energy. Currently, most of the power grids are based on many decades old vertical hierarchical infrastructures where the electric power flows in one direction from the power generators to the consumer side and the grid monitoring information is handled only at the operation side. It is generally believed that a fundamental evolution in electric power generation and supply system is required to make the grids more reliable, secure and efficient. This is generally recognised as the development of smart grids. Demand management is the key to the operational efficiency and reliability of smart grids. Facilitated by the two-way information flow and various optimization mechanisms, operators benefit from real time dynamic load monitoring and control while consumers benefit from optimised use of energy. In this thesis, various mathematical optimization techniques and game theoretic frameworks have been proposed for demand management in order to achieve efficient home energy consumption scheduling and optimal electric vehicle (EV) charging. A consumption scheduling technique is proposed to minimise the peak consumption load. The proposed technique is able to schedule the optimal operation time for appliances according to the power consumption patterns of the individual appliances. A game theoretic consumption optimization framework is proposed to manage the scheduling of appliances of multiple residential consumers in a decentralised manner, with the aim of achieving minimum cost of energy for consumers. The optimization incorporates integration of locally generated and stored renewable energy in order to minimise dependency on conventional energy. In addition to the appliance scheduling, a mean field game theoretic optimization framework is proposed for electric vehicles to manage their charging. In particular, the optimization considers a charging station where a large number of EVs are charged simultaneously during a flexible period of time. The proposed technique provides the EVs an optimal charging strategy in order to minimise the cost of charging. The performances of all these new proposed techniques have been demonstrated using Matlab based simulation studies

Traffic Scheduling in Software-defined Backhaul Network

In the past few years, severe challenges have arisen for network operators, as explosive growth and service differentiation in data demands require an increasing number of network capacity as well as dynamic traffic management. To adapt to the network densification, wireless backhaul solution is attracting more and more attentions due to its flexible deployment. Meanwhile, the software-defined network (SDN) proposes an promising architecture that can achieve dynamic control and management for various functionalities. In this case, by applying the SDN architecture to wireless backhaul networks, the traffic scheduling functionality may satisfy the ever-increasing and differentiated traffic demands. To tackle the traffic demand challenges, traffic scheduling for software-defined backhaul networks (SDBN) is investigated from three aspects in this thesis. In the first aspect, various virtual networks based on service types are embedded to the same wireless backhaul infrastructure. An algorithm, named VNE-SDBN, is proposed to solve the virtual network embedding (VNE) problem to improve the performance of the revenue of infrastructure providers and virtual network request acceptance ratio by exploiting the unique characteristics of SDBNs. In the second aspect, incoming traffic is scheduled online by joint routing and resource allocation approach in backhaul networks operated in low-frequency microwave (LFM) and those operated in millimetre wave (mmW). A digraph-based greedy algorithm (DBGA) is proposed considering the relationship between the degrees of vertices in the constructed interference digraph and system throughput with low complexity. In the third aspect, quality-of-service is provided in terms of delay and throughput with two proposed algorithms for backhaul networks with insufficient spectral resources. At last, as a trial research on E-band, a conceptual adaptive modulation system with channel estimation based on rain rate for E-band SDBN is proposed to exploit the rain attenuation feature of E-band. The results of the research works are mainly achieved through heuristic algorithms. Genetic algorithm, which is a meta-heuristic algorithm, is employed to obtain near-optimal solutions to the proposed NP-hard problems. Low complexity greedy algorithms are developed based on the specific problem analysis. Finally, the evaluation of proposed systems and algorithms are performed through numerical simulations. Simulations for backhaul networks with respect to VNE, routing and resource allocation are developed