Search

IEEE 802. 11p, which is a fundamental protocol of dedicated short—range communication in intelligent transportation systems, is evaluated in this work. The relationship of IEEE 802. 11p with other protocols in the layered architecture for DSRC, as well as the standard framing process for wireless transmission, is studied. The common problems of the orthogonal frequency division multiplexing vehicular communication system and their solutions, such as channel estimation, carrier frequency offset, and symbol time offset, are analyzed by simulation. Analysis results indicate the acceptable reliability and performance of IEEE 802. 11p. Simulation results confirm the viability of the design of related applications.

Distributed mesh sensor networks provide cost-effective communications for deployment in various smart grid domains, such as home area networks (HAN), neighborhood area networks (NAN), and substation/plant-generation local area networks. This paper introduces a dynamically updating key distribution strategy to enhance mesh network security against cyber attack. The scheme has been applied to two security protocols known as simultaneous authentication of equals (SAE) and efficient mesh security association (EMSA). Since both protocols utilize 4-way handshaking, we propose a Merkle-tree based handshaking scheme, which is capable of improving the resiliency of the network in a situation where an intruder carries a denial of service attack. Finally, by developing a denial of service attack model, we can then evaluate the security of the proposed schemes against cyber attack, as well as network performance in terms of delay and overhead.

Wireless Local Area Networks have been increasingly deployed and become very popular. They offer important advantages such as the higher flexibility and user mobility, however, this kind of networks also present some security concerns due to its broadcast nature. Security mechanisms can be classified into two groups: user authentication and data confidentiality. The IEEE 802.11i specification presents RSNA authentication mechanism, which allows user authentication employing IEEE 802.1x protocol and EAP methods. Authentication mechanisms consist in an important step of the handoff process, which occurs when a mobile node leaves the coverage area of an access point and performs association with another. Handoff results in a critical function for IEEE 802.11 MAC operation due to important delay restrictions. Thus, pre-authentication and IEEE 802.11r mechanisms have been presented to allow important latency reduction, which provide interesting results in real time communications. Besides, usually, WLAN users employ mobile devices, which provide limited capabilities in terms of energy management. In this way, in this paper, we evaluate authentication latency and battery consumption by means of an analytical model that we have developed for this purpose. The analysis also includes the influence of transmission errors, which allows the evaluation of authentication mechanisms in error-prone scenarios.

In this paper, a frame transmission method to make IEEE 802.15. 4 nodes run at a new channel and its characteristics are studied when they experience difficulties in transmission of frames due to WiFi traffic. The researches on evaluating the interference from WiFi traffic, searching for a new channel with little interference or not, and changing the operating channel are analyzed. In an wireless channel overlapped with IEEE 802.11 network, the transmission delay of IEEE 802.15.4 frames, the collision of frames in sending IEEE 802.15.4 frames without applying CSMA-CA algorithm, and the operation of IEEE 802.11 nodes are explained. A transmission method of frames including frame-formated code blocks in order to use the rest part of collided IEEE 802.15.4 frame is proposed. In the experiments of the proposed method, it is observed that frame-formated code blocks are synchronized and received by receivers in case of collision, and then the collided positions in IEEE 802.15.4 frame and the characteristics of frame reception rate are analyzed. The experimental results show that the performance of the propo sed method is improved in comparison to an existing method when we measure the time taken to send a channel change command and get the response in order to avoid the interference from WiFi traffic.

Wireless sensor networks have been widely applied in industrial applications especially since the release of IEEE 802.15.4 standard. By participating in an automobile project in which an IEEE 802.15.4 based sensor and actuator network is deployed to measure and control the vibrations of an automotive system, we need to study many metrics of IEEE 802.15.4 sensor networks e.g., packet delivery rate, latency, and energy consumption under various sampling rates. In order to provide detailed modeling of hardware and software as well as network behaviors on each sensor node, we conduct plenty of experiments on a SystemC-based wireless sensor networks simulator IDEA1, which supports the hardware and software co-simulation of sensor nodes with certain flexibility of abstraction level. Compared with the existing works on performance evaluation of IEEE 802.15.4 protocols, the main contributions of this paper are the comprehensive studies of both beacon-enabled and nonbeacon-enabled modes under various parameter settings and the beacon tracking synchronization mechanism in the IEEE 802.15.4 standard, which is ignored in most previous works. Additionally, the in-depth analysis of simulation results enables us to find the best parameter configurations to different traffic loads and application requirements, which can be used as general experiences for other applications.Copyright © 2014 John Wiley & Sons, Ltd.

We present an analytical framework for the delay analysis of the distributed coordinated scheduling in the IEEE 802.16 Wireless Network in mesh mode. We designed a queuing model that expresses the network limits accurately. The queuing model is of the type M/G/1/L developed using Linear Algebraic Queuing Theory. After modeling one node, an iterative method is used to calculate the traffic flowing in the whole network. With this model, it is possible to calculate the end-to-end delay and the throughput limit of the link layer. An algorithm is presented that applies a strategy to provide fair resource sharing. The numerical results and simulations for different topologies show that the model is accurate and that the fairness strategy effectively reduces the end-to-end delay.

In this paper, we evaluate performance of 6LoWPAN and PANA over a mesh network based on mathematical analysis, considering IEEE 802.15.4 MAC/PHY behavior, 6LoWPAN behavior including fragmentation and PANA protocol behavior. End-to-end IP packet error rate, mean end-to-end IP packet delay, PANA session failure rate and mean PANA session establishment delay are used as the performance criteria. We show tradeoff points between Long Frame and Short Frame profiles for 6LoWPAN and PANA performance. As a result of performance analysis, we show a recommended PANA profile for IEEE 802.15.4g mesh networks to use Long Frame profile as long as MAC performance metric meet certain criterion.

In this article we discuss the state of the art of (mobile) multihop ad hoc networking. This paradigm has often been identified with the solutions developed inside the IETF MANET working group, and for this reason it is called the MANET paradigm. However, they do not coincide, and in the last decade they clearly diverged. In this article, we start from the reasons why the MANET paradigm did not have a major impact on computer communications, and we discuss the evolution of the multihop ad hoc networking paradigm by building on the lessons learned from the MANET research. Specifically, we analyze four successful networking paradigms, mesh, sensor, opportunistic, and vehicular networks, that emerged from the MANET world as a more pragmatic application of the multihop ad hoc networking paradigm. We also present the new research directions in the multihop ad hoc networking field: peoplecentric networking, triggered by the increasing penetration of the smartphones in everyday life, which is generating a people-centric revolution in computing and communications. © 2014 IEEE.

To support the mobility and low cost deployment, the wireless technology is being used for number of applications. Wireless Mesh Networks (WMN) is one of the evolving technology to provide un-disrupted data connectivity to mobile users. It provides high bandwidth through efficient resource sharing, specially for areas deprived of wired connectivity. These networks also offer self-configuring, self-healing and self organizing capabilities. IEEE 802.11s is a MAC standard being proposed as an enhancement for WMN. This standard includes the use of a mandatory routing protocol at MAC layer, known as Hybrid Wireless Mesh Protocol (HWMP). However, HWMP offers weak response to congestion, especially for interactive applications. IEEE 802.11s has also proposed sharing of Congestion Control Notification Frame(CCNF) on reaching congestion threshold. In this research paper, we have proposed a congestion avoidance technique named Congestion Avoidance Hybrid Wireless Mesh Protocol (CA-HWMP). The proposed technique offers localized re-routing based upon congestion threshold, with minimal overheads. The re-routing decision is taken by the each node using CCNF received from the next hop neighbor. The proposed algorithm do not add any overhead as the CCNF is already the design part of 802.11s. This paper also shows comparison of proposed technique against HWMP under NS3 for the validation of proposed idea. From the comparison we concluded that use of CA-HWMP as replacement of HWMP significantly improves the performance of IEEE 802.11s.

The paper investigates the feasibility of using IEEE 802.11 in energy harvesting low-power sensing applications. The investigation is based on a prototype carbon dioxide sensor node that is powered by artificial indoors light. The wireless communication module of the sensor node is based on the RTX4100 module. RTX4100 incorporates a wireless protocol that duty-cycles the radio while being compatible with IEEE 802.11 access points. The presented experiments demonstrate sustainable operation but indicate a trade-off between the benefits of using IEEE 802.11 in energy harvesting applications and the energy-efficiency of the system.

IEEE 802.15.4 is the de facto standard for Wireless Sensor Networks (WSNs) that outlines the specifications of the PHY layer and MAC sub-layer in these networks. The MAC protocol is needed to orchestrate sensor nodes access to the wireless communication medium. Although distinguished by a set of strengths that contributed to its popularity in various WSNs, IEEE 802.15.4 MAC suffers from several limitations that play a role in deteriorating its performance. Also, from a practical perspective, 80.15.4-based networks are usually deployed in the vicinity of other wireless networks that operate in the same ISM band. This means that 802.15.4 MAC should be ready to cope with interference from other networks. These facts have motivated efforts to devise improved IEEE 802.15.4 MAC protocols for WSNs. In this paper we provide a survey for these protocols and highlight the methodologies they follow to enhance the performance of the IEEE 802.15.4 MAC protocol.

We present the state-of-the-art system level evaluation of the IEEE 802.22-2011 standard using a highly detailed simulator implementation in NS-2. In the evaluation our attention is focused on the effect of spatiotemporal wireless microphone (WM) activity on the performance of the IEEE 802.22-2011 network, while considering novel spectrum sensing strategies and multimedia traffic with different prioritization in IEEE 802.22-2011. Our general finding is that the IEEE 802.22-2011 standard deals well with WMs and prioritization of simultaneous multimedia traffic using different QoS profiles, while some surprising conclusions follow.

WAVE by IEEE, CALM by ISO and Car-to-Car are the popular VANET architectures. These architectures mainly focus on safety applications. IEEE 802.11p is the IEEE recommended MAC and PHY layer standard for VANET. Different VANET pro- tocol stacks recommend this standard not only for the safety applications but also other applications. In this paper, we focus on Multimedia-based ad-hoc networking and WLAN aspects for VANETs. The use of Multimedia applications is increasing day by day. Applications like Voice over IP (VoIP), video conferencing, online gaming and file transfer etc. demand time bounded and high throughput services. To fulfill these demands in a vehicular environment, there is a need to evaluate the current IEEE VANET standard for MAC (IEEE 802.11p) to know its limitations for these applications and move towards exploration of a new standard. IEEE 802.11n claims high throughput up to 300Mbps and proved to be more suitable standard for multimedia applications. In this paper, we have evaluated IEEE 802.11p and IEEE 802.11n specifically for multimedia applications in VANET. Simulation results show, IEEE 802.11n comparatively performs better for multimedia applications in urban environment in low BER (bit error rate) as well as high BER as compared to IEEE 802.11p.

Wireless communication in wireless mesh networks (WMNs), like other types of wireless networks, is vulnerable to many malicious activities such as eavesdropping. As one of the fundamental security technologies, pairwise key establishment has been widely studied to secure wireless communication. In this paper, we propose a new matrix-based pairwise key establishment scheme for mesh clients in WMNs. A fact in WMNs is that mesh routers are more powerful than mesh clients, in both communication and storage. Motivated by this fact, expensive operations can be delegated to mesh routers to alleviate the overhead of mesh clients when establishing pairwise keys between them. Compared with other matrix-based schemes, our scheme has significant advantages: any two mesh clients can directly establish pairwise keys while communication and storage costs of mesh clients are significantly reduced. This paper presents a new matrix-based pairwise key establishment scheme.Expensive operations are delegated to mesh routers.Any two mesh clients can directly establish pairwise keys.Our scheme has a very light overload of communication and storage at mesh clients.

Wireless mesh networks have emerged as high-performance and cost-effective approaches to extending the coverage area of wireless local networks and providing last-mile broadband Internet access. In this paper, we develop an analytical model to investigate delay, loss rate, and performance metrics of central mode of IEEE 802.16d mesh structure. Two well-known scenarios are selected for simulations: BS-centered and BS-cornered scenarios. In the first scenario, the base station is located at the center of the network; while in the second one, the base station is located at one the four corners of the network. In this analytical model, two major delay constraints namely queuing and scheduling delay which affect the end-to-end delay of the system have been considered. It has been shown that the height of the network is limited due to the constant frame duration. Meanwhile, the position of the BS is considered in the analysis. The simulations conducted to measure the average end-to-end delay confirm the results obtained by the analysis.

A mathematical model to analyse the saturation throughput of IEEE 802.11ac medium access control (MAC) is proposed. The main contributions of the proposed model are the integration of the transmission opportunity (TXOP) sharing mode and the consideration of variable-length MAC protocol data units, instead of a fixed-length assumption. By using the model, accurate results (within 2% relative error) for the IEEE 802.11ac TXOP sharing mode are achieved.

Summary The IEEE 802.16 standard for wireless broadband networks includes the mesh mode in its specifications, where network nodes interact to deliver packets from a client to a remote destination through intermediate nodes. This paper presents a study of the capacity of IEEE 802.16 wireless networks in mesh mode by using M/G/1/L queuing model that represents each network node by incorporating the features of the standard in order to calculate the average delay and throughput in the node. An iterative method integrates the calculation results at each node, obtaining the end-to-end delay from any node of the mesh to the Base Station. Because of multiple hops, a node far from the Base Station may have its flows damaged. To minimize this problem, we propose a criterion for a fair distribution of resources. We show the numerical results of the model which indicate a good fit when compared with simulation results. Copyright © 2013 John Wiley & Sons, Ltd.

Airtime is set as the default routing metric for the ongoing IEEE 802.11s wireless mesh networking standard. The metric is designed to minimize channel resource consumption by accounting for loss rate, bandwidth, and channel characteristics. However, the metric exhibits a noticeable ping---pong effect whose nature is still vague, and the very few references to this in the literature condemn it for being a perilous behavior. In this paper, we present a thorough study of the Airtime ping---pong effect, and highlight its correlation to the underlying rate control algorithms. Using different rate control algorithms (e.g., ARF, AARF, ONOE, AMRR and Constant rate), we establish that transmission rate adaptation is the principal cause behind the effect. We show that the effect is an inherent behavior, and that an accurate characterization of it can help improve network performance. We present a ping---pong-aware mechanism that, by detecting when a link undergoes such an effect, adapts the routing protocol for better network performance. The mechanism is O(1), decentralized, and can be easily integrated into the IEEE 802.11s routing protocol.

The interference problem is considered for modern wireless computer networks (IEEE 802.11 WLAN and IEEE 802.15 WPAN) during their operation within a common frequency range in automation systems of industrial enterprises. A universal technique is suggested for solving this problem based on estimating the energy component of the signals. As an example, two special cases of the estimation procedure are considered using an IEEE 802.15.4 standard device.

In this paper we discuss a proposition of various applications of new queueing models that have been developed within the CARMNET project in nodes of the mesh network. These models allow characteristics of systems that service multi-rate traffic to be determined, e.g., the average queue length or the average waiting time for calls of a given class. The proposed models can be used to design, analyse and optimize multiservice networks

In this paper, we propose a probability-statistical capacity-prediction scheme to provide probabilistic quality-of-service (QoS) guarantees under the high traffic load of IEEE 802.11 wireless multimedia Mesh networks. The proposed scheme perceives the state of wireless link based on the MAC retransmission statistics and calculates the statistical channel capacity especially under the saturated traffic load. Via a cross-layer design approach, the scheme allocates network resource and forwards data packets by taking the interference among flows and the channel capacity into consideration. Extensive experiments have been carried out on the basis of IEEE 802.11 protocols in order to demonstrate the superiority of the proposed scheme over the existing location-based QoS optimization delivery algorithm in terms of retransmission count, successful delivery rate, and end-to-end delay on the condition of time-varying multi-hop wireless links.

The IEEE 802.15.4 standard is able to achieve low-power transmissions in low-rate and short-distance Wireless Personal Area Networks (WPANs). It supports a Guaranteed Time Slots (GTSs) allocation mechanism for time-critical and delay-sensitive data transmissions. However, the inflexible First-Come-First-Served (FCFS) GTS allocation policy and passive deallocation mechanism significantly impair network efficiency. This paper proposes an Adaptive and Real-Time GTS Allocation Scheme (ART-GAS) to provide differentiated services for devices with different priorities, which guarantees data transmissions for time-sensitive and high-traffic devices. The bandwidth utilization in IEEE 802.15.4-based PAN is thus improved. The proposed scheme is developed based on the IEEE 802.15.4 Medium Access Control (MAC) protocol and is fully compatible with the implementation of IEEE 802.15.4 devices. It is applicable to various real-time systems built upon wireless sensor networks. Simulation results demonstrate that our ART-GAS algorithm significantly outperforms the existing GTS mechanism specified in IEEE 802.15.4 in terms of success probability, average delay, average waiting time, and CFP bandwidth utilization.

In mobile healthcare applications, the reliable transmission of the bio-data is very important. In this article, we present a reliable bio-data transmission technique for mobile healthcare monitoring service at 6LoWPAN multi-hop wireless networks. In particular, we expand IEEE 11073-20601 protocol, and propose the reliable path construction for 6LoWPAN aimed to reliably provide mobile healthcare service over wireless sensor network, using IPv6 network. 6LoWPAN is recognized possibility because it is agree with sensor network by raising Adaptation layer on the MAC layer to transmit IPv6 packets. In this article proposed minimize the algorithm complexity and reliability routing protocol because the 6LoWPAN devices are suitable for low cost, small size and battery that can be used to health care system environment. And detailed procedures and algorithms are presented. We the proposed method to prove the superiority of using NS-3 for compareing with AODV protocol.

Both IEEE 802.15.3c and IEEE 802.11ad standards define physical and medium access control layers for operation in the 60 GHz millimeter wave frequency band that is capable of multi-Gbps throughput. As both standards are used for multi-Gbps local communications, we would like to know which one is better for a given set of application domain requirements. In this paper, we compare the two standards qualitatively and quantitatively, focusing on multi-Gbps local communications. According to the quantitative performance analysis, both IEEE 802.15.3c and IEEE 802.11ad have almost the same performance in terms of throughput and delay. The qualitative comparison, however, shows that IEEE 802.11ad is more robust than IEEE 802.15.3c because the former has additional features of coexistence and backward compatibility.

Cognitive wireless mesh networks (WMN’s) are an emerged technology has made rapid changes in communication world. A wireless mesh network consists of mesh routers and mesh clients, in which mesh clients are highly mobile; due to this it should transmit continuous signaling messages to the gateway for their location registration. By transmitting signaling messages continuously more bandwidth is utilized so the overall performance of the network will be degraded. To overcome this problem we are introducing a new concept called clustering, which includes both static and dynamic clustering for mesh routers and mesh clients. By using these clustering algorithms we can reduce the signaling messages, so the overall network performance will be increased.

This article presents the TRI-media Telematic Oceanographic Network (TRITON) project, which aims to develop a high-speed and low-cost maritime communication system. The article includes information pertaining to background studies, high-level architecture, network feasibility, maritime communication environment, technology developments, prototype implementations and link performance measurements. The motivation for this project stems from the fact that there is an increasing need for low-cost and high-speed maritime communication, with demands mainly coming from regulatory and crew welfare needs. The system described in this article is a wireless mesh network based on the IEEE 802.16. An analysis of the node connectivity based on real ship traffic data shows that the network is feasible in shipping lanes with a high density of ships. The system also considers the use of an intelligent middleware to allow communications to switch back to a satellite link in cases where neighboring ships are sparse or at locations far away from mesh base stations. Protocol enhancements to both the Medium Access Control (MAC) and networking layers and a hardware design that features multiple transceivers and the implementation of antenna switching to counter sea wave reflection and rocking problems are presented. Measurements of field trials show that the proposed wireless mesh network could be an effective solution for maritime communications.

The IEEE 802.11ac amendment has been proposed to enhance the throughput of IEEE 802.11n beyond gigabit-per-second rates. In this article we present an overview of the most important features proposed in the 802.11ac amendment, including channel bonding mechanisms and multi-user MIMO.

AMI enables bi-directional exchange of information between utilities and consumers in order to maximize energy efficiency. To enable the AMI, it is essentially required to construct stable communication networks. This paper shows the AMI system based on IEEE 802.11s as one of the communication methods. Experimental results show that the wireless mesh network technology achieves a stable communication performance over a wide coverage.

IEEE 802.11 based wireless mesh networks with directional antennas are expected to be a new promising technology and an economic approach for providing wireless broadband services in rural areas. In this paper, we discuss interference models and address how they can affect the design of channel assignment in rural mesh networks. We present a new channel assignment framework based on graph coloring for rural wireless mesh networks. The goal of the framework is to allow synchronously transmitting or receiving data from multiple neighbor links at the same time, and continuously doing full-duplex data transfer on every link, creating an efficient rural mesh network without interference. Channel assignment is shown to be NP-hard. We frame this channel allocation problem in terms of Adjacent Vertex Distinguishing Edge Coloring (AVDEC). Detailed assignment results on grid topology are presented and discussed. Furthermore, we design an algorithm. Finally, we evaluate the performance of the proposed algorithm through extensive simulations and show the algorithm is effective to the regular grid topologies, and the number of colors used by the algorithm is upper bounded by Δ + 1. Hence the algorithm guarantees that the number of channels available in standards such as IEEE 802.11a is sufficient to have a valid AVDEC for many grid topologies. We also evaluate the proposed algorithm for arbitrary graphs. The algorithm provides a lower upper bound on the minimum number of channels to the AVDEC index channel assignment problem.

We propose new authentication protocols to support fast handover in IEEE 802.11-based wireless mesh networks. The authentication server does not need to be involved in the handover authentication process. Instead, mesh access points directly authenticate mobile clients using tickets, avoiding multi-hop wireless communications in order to minimize the authentication delay. Numerical analysis and simulation results show that the proposed handover authentication protocol significantly outperforms IEEE 802.11 authentication in terms of authentication delay.

For vehicular networking purposes the main communication standard approach on global scale is the IEEE 802.11p. This protocol-based system, together with the 3G cellular network, was the main elements of our car communications test-bed network. The developed test-bed implements an intelligent heterogeneous traffic safety network between cars and infrastructure. It also offers the possibility to exploit vehicle based sensor and observation data in order to generate intelligent real-time services and a service platform for vehicles. The main goal was to improve traffic safety with accident and weather condition related accurate services, but also to offer a platform for true bi-directional Internet-like networking experience tailored cost-effectively to vehicular environments. This paper presents the field test results of a new standard system for car communication, IEEE 802.11p vehicular networking measurements in Northern Finland (with supporting simulations). The results achieved in developed heterogeneous networking system (with special services) pilot testing are presented also. Based on the experience gained from both field measurements and pilot deployment, we propose a system deployment strategy for simple scenarios with general system efficiency estimation. It is shown that the solution has clear potential for a comprehensive heterogeneous vehicular communication and safety network.

This paper has designed a ZigBee application which is based on the IEEE address. This applications operating environment is TIs protocol stack called Z-Stack. The application can realize the following functions: wireless network self-organizing, the automatic acquisition and information upload. The upper machine communication protocol uses the IEEE address as device ID. This insures the application can find the datas physical source. With the help of network address, the applications speed and any other performance indicators will not drop. Using this application, the user can immediately find the accurate position directly after the security problem appeared. It has improved the efficiency of the wireless network management obviously.

Wireless multi-hop mesh network (Wireless Mesh Network, WMN), is a new network technology developed from mobile Ad hoc, widely used in the world. The paper carried out in-depth research and outlook to the key technologies, network architecture, performance and characteristics and typical application scenarios of Wireless Mesh Network.

Recent advances in wireless communication technologies have enabled the development of Wireless Sensor Networks (WSNs) that consist of low cost, power and small-size sensor nodes. ZigBee, an IEEE 802.15.4 based wireless sensor networks have been the promise of facilitating large-scale and real-time data processing in complex environments. Mobility management is a challenging task in the IEEE 802.15.4 based wireless sensor network. Work in this paper comprises of recovery of the network in case of PAN coordinator failure using mobile node with trajectory. The simulation model consists of IEEE 802.15.4 based wireless sensor network which involves a mobile node deployed near PAN coordinator. The deployed mobile node routes through the coverage area of each PAN coordinator to recover the network. The work is also implicated with Beacon and Nonbeacon enabled IEEE 802.15.4 based wireless sensor network. The simulation model is done by using OPNET. Performances metrics like throughput and delay in the network are determined and analyzed.

Leader election problem has been studied in the past to improve the efficiency of both distributed systems and wireless ad hoc and sensor networks. Yet, few research has been done on the leader election process for wireless mesh networks. Most of the existing leader election protocols consider wireless networks in general, without focusing on the particularities of mesh networks. Thus, these protocols are not suitable for wireless mesh networks. The lack of research on this issue has motivated us to design a leader election protocol dedicated to wireless mesh networks. In this work, we propose an efficient leader election protocol for wireless mesh network, which is based on the construction of a spanning tree that includes all wireless mesh routers. The protocol elects the node with the longest remaining battery life. In this paper, we give a detailed description of the proposed protocol, prove its correctness, discuss its message and time complexities and then evaluate its performance through simulation using ns-2. We show that our protocol is efficient and scales well with the increase in number of mesh routers and mesh clients.

IEEE 802.22 is a cognitive radio-based Wireless Regional Area Network (WRAN) standard that allows opportunistic access to idle or underutilized sub-900 MHz TV bands by unlicensed (secondary) networks. Though most of the standard has been laid out, there is still no consensus on the channel access policies for the uncoordinated secondary networks. Hence, the possibility of interference always exists. Moreover, in the absence of any control channel, the problem of establishing a connection becomes even more challenging, more so in the presence of hidden incumbents. In this paper, we address the above-mentioned self-coexistence problem among the IEEE 802.22 networks and provide novel solutions to improve the IEEE 802.22 air-interface. We use an interference-aware graph-theoretic technique and propose Utility Graph Coloring (UGC) for allocating spectrum to different IEEE 802.22 base stations such that they can coexist with the least interference, thereby maximizing the system spectrum utilization. We also consider allocation fairness among the networks in terms of minimal fairness, proportional fairness, and complete fairness. With the spectrum allocated to the IEEE 802.22 networks, we propose enhancements to the IEEE 802.22 MAC layer to maximize spectrum usage efficiency. In particular, we make use of aggregation and fragmentation of channel carriers, dynamic multiple broadcast messages, and aggressive contention resolution. Through simulation experiments, we show how the proposed techniques can increase the spectral efficiency and spectrum utilization, and still maintain fairness. We show that the spectral efficiency obtained with UGC is more than three times compared to the existing standard. The average number of collisions among the IEEE 802.22 enabled devices is significantly reduced, resulting in low connection setup delay, enhanced system performance, and higher spectrum allocation for data transmissions.

Wireless mesh networks (WMNs) are the key technology of wireless access network for wireless Internet application. WMNs exploit mesh gateways for delivering traffic to or from the end-users with a multihop wireless backbone. Because the traffic volume is expected too high for single mesh gateway, the adoption of multiple mesh gateways is very essential. Hence, a traffic balancing algorithm becomes vital to be incorporated into the routing protocol that used in the WMNs. In this paper, we propose an optimal latency balancing (OLB) algorithm, which is used to balance the traffic load among the mesh gateways and to improve the latency of packet sending. The proposed OLB algorithm effectively finds the potential traffic flows to be switchable until the inter-domain traffic volume is balanced. Simulation results reveal that the performance of routing protocol with the proposed OLB algorithm is improved in terms of latency, hop count, network throughput, and packet delivery ratio.