Static Wireless Networks Research Articles

PSR: A Lightweight Proactive Source Routing Protocol For Mobile Ad Hoc Networks

Opportunistic data forwarding has drawn much attention in the research community of multihop wireless networking, with most research conducted for stationary wireless networks. One of the reasons why opportunistic data forwarding has not been widely utilized in mobile ad hoc networks (MANETs) is the lack of an efficient lightweight proactive routing scheme with strong source routing capability. In this paper, we propose a lightweight proactive source routing (PSR) protocol. PSR can maintain more network topology information than distance vector (DV) routing to facilitate source routing, although it has much smaller overhead than traditional DV-based protocols [e.g., destination-sequenced DV (DSDV)], link state (LS)-based routing [e.g., optimized link state routing (OLSR)], and reactive source routing [e.g., dynamic source routing (DSR)]. Our tests using computer simulation in Network Simulator 2 (ns-2) indicate that the overhead in PSR is only a fraction of the overhead of these baseline protocols, and PSR yields similar or better data transportation performance than these baseline protocols.

Data Delivery Method Based on Neighbor Nodes’ Information in a Mobile Ad Hoc Network

This paper proposes a data delivery method based on neighbor nodes' information to achieve reliable communication in a mobile ad hoc network (MANET). In a MANET, it is difficult to deliver data reliably due to instabilities in network topology and wireless network condition which result from node movement. To overcome such unstable communication, opportunistic routing and network coding schemes have lately attracted considerable attention. Although an existing method that employs such schemes, MAC-independent opportunistic routing and encoding (MORE), Chachulski et al. (2007), improves the efficiency of data delivery in an unstable wireless mesh network, it does not address node movement. To efficiently deliver data in a MANET, the method proposed in this paper thus first employs the same opportunistic routing and network coding used in MORE and also uses the location information and transmission probabilities of neighbor nodes to adapt to changeable network topology and wireless network condition. The simulation experiments showed that the proposed method can achieve efficient data delivery with low network load when the movement speed is relatively slow.

Analysis and Optimization of Resource Control in High-Speed Railway Wireless Networks

This paper considers a joint optimal design of admission control and resource allocation for multimedia services delivery in high-speed railway (HSR) wireless networks. A stochastic network optimization problem is formulated which aims at maximizing the system utility while stabilizing all transmission queues under the average power constraint. By introducing virtual queues, the original problem is equivalently transformed into a queue stability problem, which can be naturally decomposed into three separate subproblems: utility maximization, admission control, and resource allocation. A threshold-based admission control strategy is proposed for the admission control subproblem. And a distributed resource allocation scheme is developed for the mixed-integer resource allocation subproblem with guaranteed global optimality. Then a dynamic admission control and resource allocation algorithm is proposed, which is suitable for distributed implementation. Finally, the performance of the proposed algorithm is evaluated by theoretical analysis and numerical simulations under realistic conditions of HSR wireless networks.

SCAR: A Coding-Aware Routing Protocol with Self-Recommendation in Static Wireless Ad Hoc Networks

There have been researchers working on the design of coding-aware routing protocols to exploit the power of network coding in static wireless ad hoc networks. However, most of them have overlooked the fact that routing decisions for multiple flows need to be coordinated in order to achieve maximum throughput. A mechanism to alter prior routing decisions is mandatory for this purpose. In this paper, we propose Self-recommendation coding-aware routing (SCAR), to provide such a mechanism. With intermediate nodes sensing the arrival of new flows, they can send self-recommendations to source nodes, triggering a route-change procedure. In the route-change procedure, adjustments are applied to the route metrics so that the newly recommended route can be fairly weighed without bias. A thorough analysis of coding structures is carried out, and a series of indicators are devised to predict how much throughput benefits we can gain from the mere knowledge of the topology. The rationale behind the protocol design and the effectiveness of the indicators are further justified by a series of simulations. Results show that SCAR can exploit coding opportunities better and provide higher throughput than other coding-aware routing protocols. It is also shown that the opportunity of throughput gain is ubiquitous and it is tested on many typical topologies.

Investigating quality routing link metrics in Wireless Multi-hop Networks

In this paper, we propose a new Quality Link Metric (QLM), “Inverse Expected Transmission Count (InvETX),” in Optimized Link State Routing (OLSR) protocol. Then, we compare performance of three existing QLMs which are based on loss probability measurements: Expected Transmission Count (ETX), Minimum Delay (MD), and Minimum Loss (ML) in Static Wireless Multi-hop Networks (SWMhNs). A novel contribution of this paper is enhancement in conventional OLSR to achieve high efficiency in terms of optimized routing load and routing latency. For this purpose, first we present a mathematical framework, and then to validate this frame work, we select three performance parameters to simulate default and enhanced versions of OLSR. The three chosen performance parameters are throughput, Normalized Routing Load, and End-to-End Delay. From the simulation results, we conclude that adjusting the frequencies of topological information exchange results in high efficiency.

The Improvement of End to End Delays in Network Management System using Network coding

In this paper, we consider the application of network coding(NC) for network management system of Radio and Television Broadcasting Stations in wireless network using a narrow band radios modem &Routers ) as a means of transmission to communicate between the loins broadcast TV/FM stations . Our main contribution is the application of NCimproved by the proposed an effective strategy,called Fast Forwarding Strategy (FFS) compared to a classical routing strategy with a level of providing guarantees of service quality (QoS) expressed in terms of reducing the End-to-End Delays (EED) from source to destination.The practical and theoretical study, carried out by the authors, show that the EED of proposed strategy outperforms that of the classical strategy.

레일리 페이딩 채널을 통해 결합된 등가 이득 협력 라우팅의 에너지 효율

In this paper, we propose a multi-hop cooperative transmission protocol to obtain energy savings in static wireless networks. Each terminal in the network is equipped with a single antenna and each receiver uses equal gain combining technique (EGC) to combine received signals. We also propose a power allocation strategy which optimizes the total transmit power at each stage. Monte-Carlo simulations are presented to evaluate and compare performance of the proposed protocol with the multi-hop direct transmission (MDT) and the cooperative routing protocol proposed by Khadani [8], in terms of the average total transmit power and the average number of required stages.

Estimating the Cardinality of a Mobile Peer-to-Peer Network

Collecting information from mobile peer-to-peer (P2P) networks has important civilian and military applications. One problem is to determine the cardinality, i.e., the number of nodes, in a large mobile system. In a stationary wireless network, it can be trivially solved through a flooding-based query. However, the problem becomes much more challenging for mobile P2P networks whose topologies are constantly changing. In this paper, we present two novel statistical methods, called the circled random walk and the tokened random walk, to address this interesting problem. The circled random walk is simpler to implement and works well in networks of high mobility, whereas the tokened random walk works well with high or low mobility. These methods provide cardinality estimation by involving only a small subset of the nodes. They make tradeoff between overhead and estimation accuracy. The estimation error can be made arbitrarily small at the expense of larger overhead.

Context-aware Greedy Scheduling Algorithm in Wireless Network

In order to measure the link’s interference in static heterogeneous wireless networks, we need to know its context information, but the context information can not be informed before the link allocates the time slot. Because of the highly inadequate collection and the use of traditional scheduling algorithms for link interference information, which severely limits their performance, this paper proposes the context-aware greedy scheduling algorithm. This paper analyses the cumulative effect of interference and the sequence detection feature of the serial interference cancellation (SIC, successive interference cancellation). The algorithm researches the strategy of choosing time slot, defines tolerance to measure the saturation of the link set and gives two kinds of new heuristic time slot selection mechanism. Finally, network simulator (NS 2) conducts simulation experiments which adopt performance evaluation as throughput to assess the performance of scheduling algorithm of this paper in the case of a single multi-hop. The experiments show that: the scheduling performance of context-aware greedy scheduling algorithm in heterogeneous static wireless network has been improved.

EasiND: Neighbor Discovery in Duty-Cycled Asynchronous Multichannel Mobile WSNs

Neighbor discovery is one of the first steps to establish communication links between sensor nodes; thus it becomes a fundamental building block for wireless sensor networks (WSNs). Traditional neighbor discovery protocols mainly focus on static wireless networks or networks where all nodes operate on the same frequency. However, the proliferation of mobile devices and multichannel communications post new challenges to neighbor discovery problem. In this paper, we present a neighbor discovery protocol named EasiND for asynchronous duty-cycled multichannel mobile WSNs. First, we propose a neighbor discovery system based on quorum system, which can bound the discovery latency in multichannel scenarios with low power consumptions. Second, we design an optimal asynchronous neighbor discovery system for multichannel mobile WSNs based on cyclic difference set. It is optimal in the sense that it minimizes the power consumption with bounded discovery latency under desired duty cycles. Finally, we validate the performance of EasiND through both theoretical analysis and test-bed evaluations. EasiND provides a 33.3% reduction in power-latency product in theory compared to U-Connect. Meanwhile, test-bed evaluation results show that EasiND decreases average discovery latency by up to 86% compared to U-Connect and achieves at least 93.5% average fraction of discoveries in a predefined time limitation under various network conditions.

Streaming 3D meshes over thin mobile devices

We are witnessing a significant growth in applications using thin mobile devices, such as social networks, virtual walkthrough, massively multiplayer online gaming (MMOG), and augmented reality (AR), just to mention a few. Virtual environments (VE) based class of applications have recently attracted a large number of users. Applications that applied the conventional client-server architecture require the VE to be stored on the client, which is not very feasible due to the client's memory constraints. To address this issue, 3D streaming techniques have been designed and are widely used nowadays. However, several challenges exist and affect the user's Quality of Experience (QoE). By all means, these challenges need to be resolved before the 3D streaming technology over thin mobile devices becomes a commodity. In this paper, we provide a survey on the existing 3D streaming techniques by classifying them based on the nature of the application, and we centralize our attention on methods applied to adapt 3D streaming techniques to the changes in the wireless network conditions. Therefore, we discuss the challenges that the 3D streaming techniques face from a network point of view, as well as the approaches and solutions proposed.

Autonomous aggregation in location aware ad hoc wireless networks

ABSTRACTGossip‐based epidemic protocols are used to aggregate data in distributed systems. This fault‐tolerant approach neither require maintenance of any global network state nor knowledge of network structure. However, although gossip‐based aggregation algorithms scale well for graphs with good expansion, their efficiency for sparse graphs is unexamined. In this paper, we analyze the feasibility and efficiency of a gossip aggregation protocol in wireless networks with low expansion. We propose a modification of the existing aggregation algorithm for use in locality‐aware, sparse, and static wireless networks. Our protocol terminates autonomously, uses less bandwidth than the original version, and removes the need for the leader election process while counting network nodes. Aggregates are calculated only over nodes placed in the vicinity, and nodes communicate only with their immediate neighbors by using a wireless broadcast. We evaluate our approach by simulation on sparse, irregular graphs with low expansion for the simplified system model. Furthermore, we analytically assess the worst‐case convergence time of this protocol for sparse wireless networks and also for the simplified system model. The proposed protocol can be used in the monitoring and alarming applications in wireless networks. Copyright © 2012 John Wiley & Sons, Ltd.

On the minimum latency transmission scheduling in wireless networks with power control under SINR constraints

AbstractIn order to alleviate interference and contention in a wireless network, we may exploit the existence of multiple orthogonal channels or time slots, thus achieving a substantial improvement in performance. In this paper, we study a joint transmission scheduling and power control problem that arises in wireless networks. The goal is to assign channels (or time slots) and transmitting powers to communication links such that all communication requests are processed correctly, specified quality‐of‐service requirements are met, and the number of required time slots is minimised. First, we formulate the problem as a mixed‐integer linear programming. Then, we show that the problem considered is non‐deterministic polynomial‐time hard, and subsequently, we propose non‐trivial bounding techniques to solve it. Optimisation methods are also discussed, including a column generation approach, specifically designed to find bounds for the transmission scheduling problem. Moreover, we develop optimisation techniques in which the bounding techniques are integrated in order to derive the optimal solution to the problem faster. We close with an extensive computational study, which shows that despite the complexity of the problem, the proposed methodology scales to problems of non‐trivial size. Our algorithms can therefore be used for static wireless networks where propagation conditions are almost constant and a centralised agent is available (e.g. cellular networks where the base station can act as a centralised agent or wireless mesh networks), and they can also serve as a benchmark for the performance evaluation of heuristic, approximation or distributed algorithms that aim to find near‐optimal solutions without information about the whole network. Copyright © 2013 John Wiley & Sons, Ltd.

Wireless security: securing mobile UMTS communications from interoperation of GSM

ABSTRACTWireless communications have revolutionized the way the world communicates. An important process used to secure that communication is authentication. As flaws in the security of a wireless network are discovered, new protocols and algorithms are required to meet those security issues. When creating new algorithms and systems, it is possible that the existing equipment may not be able to implement the new protocols, which means that integration may be required to transition from an old security protocol to the new more secure protocol. Stationary wireless networks were created without a strong need to integrate protocols and have simply developed slightly more secure protocols to protect old equipment. New protocols in stationary wireless networks are implemented without integration as a requirement. Mobile wireless networks have the requirement of allowing old equipment to use the entire network as it is advantageous to allow new mobile equipment to connect to old networking equipment to increase coverage areas and for old equipment to connect to new towers for roaming and billing. This requirement for mobile networks means that integration is required. There are flaws in this integration of Global System for Mobile Communications (GSM) into Universal Mobile Telecommunications System (UMTS) networks. Those flaws are analyzed, and two practical solutions are proposed. Copyright © 2012 John Wiley & Sons, Ltd.

Evaluation of the rate of the data transfer between vehicles and base stations in wireless networks

This paper presents two mathematical models. The first is used to determine the number of mobile objects depending on the distance to the base station of a wireless transport network. On the basis of real experimental data, the second model was developed to determine the actual rate of the data transfer in a wireless transport network depending on the number N of mobile objects covered by the base station.

Depth-color based 3D image transmission over wireless networks with QoE provisions

The deployment of 3-D image techniques is one of the most promising fields among the development of new applications for natural image scenes. Driven by urgent demands from industry and users, 3-D image technology has received significant research attention in recent years. 3D image streaming gives users an extra dimension of visual sense that greatly improves the liveliness and joyfulness of user experience. However, they also raise new challenges (e.g., bandwidth and energy efficiency) especially in achieving satisfactory Quality of Experience (QoE) performances. QoE has become critical multimedia quality metrics determining whether a potential multimedia application or service is successful or not. In this paper, we propose a QoE-driven wireless 3D image transmission scheme with depth-color source coding adaptations according to the wireless network conditions. Specifically, our contribution includes: (1) developing a patch-pixel based source coding scheme for 3D image transmission; (2) proposing a 3D image quality model; (3) and developing a quality-driven 3D image transmission approach based on the quality model. Experimental results demonstrate that the proposed techniques can significantly improve the QoE of 3D image over wireless networks.

Utility-based bandwidth adaptation in mission-oriented wireless sensor networks

This article develops a utility-based optimization framework for resource sharing by multiple competing missions in a mission-oriented wireless sensor network (WSN) environment. Prior work on network utility maximization (NUM) based optimization has focused on unicast flows with sender-based utilities in either wireline or wireless networks. In this work, we develop a generalized NUM model to consider three key new features observed in mission-centric WSN environments: i) the definition of the utility of an individual mission (receiver) as a joint function of data from multiple sensor sources; ii) the consumption of each sender's (sensor) data by multiple missions; and iii) the multicast-tree-based dissemination of each sensor's data flow, using link-layer broadcasts to exploit the “wireless broadcast advantage” in data forwarding. We show how a price-based, distributed protocol (WSN-NUM) can ensure optimal and proportionally fair rate allocation across multiple missions, without requiring any coordination among missions or sensors. We also discuss techniques to improve the speed of convergence of the protocol, which is essential in an environment as dynamic as the WSN. Further, we analyze the impact of various network and protocol parameters on the bandwidth utilization of the network, using a discrete-event simulation of a stationary wireless network. Finally, we corroborate our simulation-based performance results of the WSN-NUM protocol with an implementation of an 802.11b network.

IMPLEMENTATION AND VALIDATION OF AN ADAPTIVE FECMECHANISM FOR VIDEO TRANSMISSION

This research focuses on investigating the FEC mechanism as an error recovery over a wireless network. The existing adaptive FEC mechanism faces a major drawback, which is the reduction of recovery performance by injecting too many excessive FEC packets into the network. Thus, this paper proposes the implementation of an enhanced adaptive FEC (EnAFEC) mechanism for video transmission together with its validation process. There are two propositions in the EnAFEC enhancement, which include block length adaptation and implementation, and suitable smoothing factor value determination. The EnAFEC adjusts the FEC packets based on the wireless network condition so that excessive FEC packets can be reduced. The proposed enhancement is implemented in a simulation environment using the NS-2 network simulation. The simulation results show that EnAFEC generates less FEC packets than the other types of adaptive FEC (EAFEC and Mend FEC). In addition, a validation phase is also conducted to verify that the proposed enhancement is functioning correctly, and represents a real network situation. In the validation phase, the results obtained from the simulation are compared to the outputs of the other adaptive FEC mechanisms. The validation results show that the mechanism is successfully implemented in NS2 since the number of packet loss falls under the overlapping confidence intervals.

Performance analysis for relay networks with hierarchical support vector machines

SUMMARYIn this paper, we consider a cooperative relay scheme for a mobile network with MIMO technology. The channel capacity for two well‐known relaying schemes are investigated: analogue relaying (amplify and forward) and digital relaying (decode and forward) from a mobile device to the base station through a relay node. In order to further increase the channel capacity, we propose an efficient hierarchical procedure based on support vector machine, namely hierarchical support vector machines (HSVM), to estimate the wireless networks condition approximately and design two ways (matched filter and minimum mean square error filter) of increasing the channel capacity according to the estimated wireless network condition. The proposed HSVM can estimate the wireless networks condition in much shorter time compared with the traditional minimum mean square error scheme without incurring much estimation error, which is spatial, useful for delay sensitive communication. For digital relaying, the effect of imperfect channel decode is also addressed. Our numerical results demonstrate the reduction of estimation complexity by adopting HSVM and the significant improvement of network capacity by applying the matched filter weight at relay nodes according to the network estimation. Copyright © 2011 John Wiley & Sons, Ltd.

A Novel Approach For Handoff Avoidance And Qos Improvement In Wlan

Maximizing network throughput while providing fairness is one of the key challenges in wireless LANs (WLANs). Dense deployments of WLANs suffer from increased interference and, as a result, reduced capacity and wireless network conditions in general are diverse owing to both traffic and wireless channel variations. Hence effective mechanisms are required to exploit the diversity across a multiple access points and to provide a uniform load distribution in order to improve the QoS of users and to improve the overall composite capacity. In this paper, we propose a handoff scheme considering the current active application in use rather than a single fixed threshold value and dynamically changing the threshold value depending upon the currently active applications. In addition to it, we also propose a pro-active Load Balancing scheme which completely avoids unnecessary overloading of access points by considering the load at the target access point before associating with it.