Wireless Community Research Articles

Design and Implementation of the Application Layer Communication Protocol based on Wireless Sensor Network

The user-defined communication protocol is the key step to develop application system based on Wireless Sensor Network. Through the analysis on the application of the wireless sensor network architecture and communication needs, a kind of simple and practical application layer communication protocol with detailed design of protocol data structure is proposed in this paper. Based on that, a communication protocol programming prototype is written in C# language. Through the test of wireless sensor network intelligent community monitoring system, it proves that the system data transmission based on this proposal is reliable and programming is simple and convenient. DOI: http://dx.doi.org/10.11591/telkomnika.v11i8.3141

Service Discovery Algorithm Based on Service Popularity in Wireless Community Network

In this paper, we propose an algorithm for cluster generating and service discovery based on service popularity in wireless community network,which makes full use of the imbalance of the service request in the network, leading to that the requests could be replied quickly in shorter time. At the same time, the algorithm could adapt well to the wireless environment and incur less update information when the topology is changed. According to the simulation in the OMNET++, our algorithm performs better than the flooding and CRP in several aspects.

Practical conflict graphs for dynamic spectrum distribution

Most spectrum distribution proposals today develop their allocation algorithms that use conflict graphs to capture interference relationships. The use of conflict graphs, however, is often questioned by the wireless community because of two issues. First, building conflict graphs requires significant overhead and hence generally does not scale to outdoor networks, and second, the resulting conflict graphs do not capture accumulative interference. In this paper, we use large-scale measurement data as ground truth to understand just how severe these issues are in practice, and whether they can be overcome. We build "practical" conflict graphs using measurement-calibrated propagation models, which remove the need for exhaustive signal measurements by interpolating signal strengths using calibrated models. These propagation models are imperfect, and we study the impact of their errors by tracing the impact on multiple steps in the process, from calibrating propagation models to predicting signal strength and building conflict graphs. At each step, we analyze the introduction, propagation and final impact of errors, by comparing each intermediate result to its ground truth counterpart generated from measurements. Our work produces several findings. Calibrated propagation models generate location-dependent prediction errors, ultimately producing conservative conflict graphs. While these "estimated conflict graphs" lose some spectrum utilization, their conservative nature improves reliability by reducing the impact of accumulative interference. Finally, we propose a graph augmentation technique that addresses any remaining accumulative interference, the last missing piece in a practical spectrum distribution system using measurement-calibrated conflict graphs.

Radio communications: components, systems, and networks [Series Editorial

Dear readers: As we continue this Series in 2013, we plan to bring you a variety of topics related not only to the leading trends in wireless communications, but also those investigating new applications of radio communication principles. The topics that continue to dominate the interests of the wireless community are Long Term Evolution (LTE) and related cellular networking techniques. In addition, we see a growing trend in different applications of wireless networks, with machine-to-machine (M2M) being at the forefront, opening new and exciting opportunities.

Mapping Cognitive Radio System Scenarios into the TVWS Context

Cognitive Radio has been one of the key research topics in the wireless community for about 10 years. The digital switch-over in the TV bands provides opportunities for Cognitive Radio Systems (CRS...

Ultra-wide band sensor networks in oil and gas explorations

Seismic exploration and monitoring for oil and gas reservoirs is a peculiar application that requires a large number (1000-2000 nodes/sqkm) of geophone sensors deployed outdoors over large areas (≥ 40 sqkm) to measure backscattered wave fields from artificial sources. A storage/processing unit or sink node collects the measurements from all the geophones to obtain an image of the sub-surface. The existing cabling system to connect sensors is known to cause inefficiencies, large logistic and weight costs, as well as insufficient flexibility in survey design. Oil companies are therefore expecting that wireless connectivity will provide the enabling technology for future seismic explorations. This application represents a new challenging research area for the wireless community. Early results suggest that current off-the-shelf radio solutions do not guarantee the minimum requirements in terms of system usability and energy consumption, not even for current deployment size. This article presents a tutorial view to introduce the basic principles of seismic acquisition systems that are necessary to define the wireless geophone network specifications. Strict sampling synchronization constraint over large geographic areas, high precision sensor localization, and high data rate are all requirements calling for a scalable network system where Ultra-Wide Band radio transmissions play a key role as the only viable technology.

Communication Systems and Image Processing Technology

The wireless communications research communities are continuously working towards the activities for the fourth generation (4G) of communication systems. The community has generated a number of promising solutions for significant improvements in system performance. Adaptive coding and modulation, iterative (turbo) decoding algorithms, space–time coding, multiple antennas and MIMO channels, multicarrier modulation, multiuser detection and ultra wideband radio are examples of enabling technologies for 4G. Antenna arrays and MIMO technology is useful in urban warfare, where traditional communication platforms are unable to operate. The wireless communications research communities are continuously working towards the activities for the fourth generation (4G) of communication systems. The community has generated a number of promising solutions for significant improvements in system performance. Adaptive coding and modulation, iterative (turbo) decoding algorithms, space–time coding, multiple antennas and MIMO channels, multicarrier modulation, multiuser detection and ultra wideband radio are examples of enabling technologies for 4G. Antenna arrays and MIMO technology is useful in urban warfare, where traditional communication platforms are unable to operate. Defence Science Journal, 2013, 63(1), pp.3 -5 , DOI:http://dx.doi.org/10.14429/dsj. 63.3757

Proportional fairness in MAC layer channel access of IEEE 802.11s EDCA based wireless mesh networks

Fairness provisioning in IEEE 802.11s EDCA based Wireless Mesh Networks (WMNs) is a very challenging task due to relayed traffic and traffic load variation among mesh routers. Because of bursty traffic in general purpose community wireless mesh networks, proportional fairness is more suited than max–min fairness, where mesh routers and clients should get channel access proportional to their traffic load. However, proportional fairness is hard to achieve by solving optimization function because of non-linearity and non-concave property of the objective function. In this paper, a probabilistic approach is proposed to provide proportional fairness without solving global non-linear and non-concave optimization. Every mesh node use a load estimation strategy to estimate total traffic load that it needs to forward. The required channel share of a mesh node should be proportional to its traffic load, whereas, the total normalized channel share for all the contending mesh nodes should be kept less than unity to satisfy the clique constraint. The network architecture and contention property in WMN are explored to deduce the required channel share of mesh nodes. A probabilistic approach is used to tune the contention window based on the difference between actual channel share and required channel share, so that the node with more traffic load gets more channel share. A discrete time Markov Chain based modeling is used to deduce the overall network throughput for the proposed scheme. Simulation result shows that the proposed scheme works better than the standard IEEE 802.11s based EDCA MAC in terms of fairness and throughput.

Load-balanced Multicast Tree Routing in Multi Channel Multi Radio Wireless Mesh Networks Using a New Cost Function

Wireless Mesh Network (WMN) is new emerging technology that offers low-cost high-bandwidth community wireless services. This type of network requires carefully assignment of resources and load balancing in order to provide the quality guarantees to traffic flows. Load balancing avoids the creation of bottleneck nodes, and increases the network efficiency. This paper addresses the problem of multicast load balancing in Multi-Channel Multi-Radio WMNs (MCMR-WMNs). In this regard, we introduce a novel load-aware dynamic cost function to weight the links of the network. Proposed cost function considers both the benefits of Wireless Broadcast Advantage (WBA) as well as the problem of load balancing. Also, we propose a Load-balanced Multicast Tree Routing (LMTR) algorithm which provides balanced multicast trees using the defined cost function. The proposed on-demand routing scheme not only minimizes the number of transmissions, but also tries to distribute the traffic among the nodes fairly and consequently decreases the interference in the network. We also demonstrate how proposed scheme can control the trade-off between load balancing and delay. Our extensive simulations in various networks with grid and random topologies show the efficiency of LMTR in load balancing. As you will see, LMTR significantly avoids the creation of bottleneck nodes and reduces the standard deviation of traffic load on mesh routers.

Valuable Interactive Interface for Wireless Lobby Community - Focused on University Lobby -

Valuable Interactive Interface for Wireless Lobby Community - Focused on University Lobby -

Ubiquitous Sensor Networking for Development (USN4D): An Application to Pollution Monitoring

This paper presents a new Ubiquitous Sensor Network (USN) Architecture to be used in developing countries and reveals its usefulness by highlighting some of its key features. In complement to a previous ITU proposal, our architecture referred to as “Ubiquitous Sensor Network for Development (USN4D)” integrates in its layers features such as opportunistic data dissemination, long distance deployment and localisation of information to meet the requirements of the developing world. Besides describing some of the most important requirements for the sensor equipment to be used in a USN4D setting, we present the main features and experiments conducted using the “WaspNet” as one of the wireless sensor deployment platforms that meets these requirements. Furthermore, building upon “WaspNet” platform, we present an application to Air pollution Monitoring in the city of Cape Town, in South Africa as one of the first steps towards building community wireless sensor networks (CSN) in the developing world using off-the-shelf sensor equipment.

Troubleshooting Assistance Services in Community Wireless Networks

We have identified new services intended for users and administrators of community wireless networks. Troubleshooting assistance services will assist the users during solution of communication problems, gathering data for expert analysis, informing the user about the state of the network (including outages), and so forth. Network administrators will be provided with a unique tool supporting the network analysis, operation, and development. We have mainly focused on the use cases and prerequirements—the problem of topology discovery.

Enabling location-aware quality-controlled access in wireless networks

Location-based services (LBSs), such as location-specific contents-providing services, presence services, and E-911 locating services, have recently been drawing much attention in wireless network community. Since LBSs rely on the location information in providing services and enhancing their service quality, we need to devise a framework of directly using the location information to provide a different level of service differentiation and/or fairness for them. In this paper, we investigate how to use location information for QoS provisioning in IEEE 802.11-based Hot Spot networks. Location-based service differentiation is different from existing QoS schemes in that it assigns different priority levels to different locations rather than flows or stations and schedules network resources to support the prioritized service levels. In order to realize such the location-based service differentiation, we introduce the concept of per-location target load to simply represent the desirable rate of traffic imposed to the network, which is dynamically changing due to the number of stations. The load consists of per-location load, which directly quantifies per-location usage of link capacity, and network-wide load, which indirectly calibrates the portion of per-location load contributed to the network-wide traffic. We then propose a feedback framework of provisioning service differentiation and/or fairness according to per-location target load. In the proposed framework, the load information is feedback to traffic senders and used to adjust their sending rate, so that per-location load does not deviate from a given per-location share of wireless link capacity and lays only tolerable traffic on the network in cooperation with other locations. We finally implemented the proposed framework in ns-2 simulator and conducted an extensive set of simulation study so as to evaluate its performance and effectiveness. The simulation results indicate that the proposed framework provides location-based service differentiation and/or fairness in IEEE 802.11 Hot Spot networks, regardless of the number of stations in a location, traffic types, or station mobility.

An Open-Source Archiving System

Establishment of a Web-based repository for wireless multipath channel measurement data would make it possible for the researchers to pool their datasets to yield more reliable or broadly applicable results or to extract additional value from data that may have been collected for other purposes. It would also allow the validity of models derived from certain data sets to be more easily tested against other data sets than at present. Moreover, ongoing developments in Web technologies will greatly add to the capabilities of such repositories in the coming years. While the wireless community would greatly benefit from the establishment of such a repository for channel measurement data, account must be taken of the significant differences between wireless channel-response data and data collected in other scientific fields. A particu ar challenge is to ensure that essential details concerning the measurement equipment used to collect the data, the manner in which the equipment was calibrated and verified, the data collection procedure, and details of the environment in which the data were collected are adequately documented and linked to the channel response data. Nevertheless, it seems likely that the return from such a wireless channel-response data repository would justify the effort required to set up and maintain it.

An introduction to millimeter-wave mobile broadband systems

Almost all mobile communication systems today use spectrum in the range of 300 MHz-3 GHz. In this article, we reason why the wireless community should start looking at the 3-300 GHz spectrum for mobile broadband applications. We discuss propagation and device technology challenges associated with this band as well as its unique advantages for mobile communication. We introduce a millimeter-wave mobile broadband (MMB) system as a candidate next generation mobile communication system. We demonstrate the feasibility for MMB to achieve gigabit-per-second data rates at a distance up to 1 km in an urban mobile environment. A few key concepts in MMB network architecture such as the MMB base station grid, MMB interBS backhaul link, and a hybrid MMB + 4G system are described. We also discuss beamforming techniques and the frame structure of the MMB air interface.

SWARM: The Power of Structure in Community Wireless Mesh Networks

Community wireless networks (CWNs) have been proposed to spread broadband network access to underprivileged, underprovisioned, and remote areas. Research has focused on optimizing network performance through intelligent routing and scheduling, borrowing solutions from mesh networks. Surprisingly, however, there has been no work on how to make efficient use of multiple channels in CWNs in the presence of multiple gateways and a single radio per device. In fact, today's deployments in underprivileged areas are primarily single-radio and do operate on a single channel. Frequency selection in such CWNs is very complex because it does not only determine the nodes' channel of operation, but also the gateway and the routing tree to the gateway-a rather computationally intensive task. In this paper, we propose, design, implement, and evaluate SWARM, a practical system that allows a CWN to make effective use of the available wireless channels in order to offer globally optimal performance. SWARM improves performance versus current single-channel protocols by up to 7.7 × in our experiments. Moreover, while we should be expecting performance gains due to channel diversity, we clearly demonstrate that up to 3.7 × improvement is attributed to the network organization into efficient traffic distribution structures.

Wireless community networks: an alternative approach for nomadic broadband network access

Low-cost wireless LAN equipment operating in unlicensed spectrum has revolutionized local area communications, introducing novel schemes for open wireless connectivity and even new business models. The ease of deployment of Wi-Fi has made it ubiquitous in densely populated urban areas, and it was just a matter of time before wireless communities emerged. Using inexpensive wireless technology to communicate, autonomous wireless internetworks have been built, offering a variety of broadband services. Based on our own experience participating in one of the largest wireless communities worldwide, the Athens Wireless Metropolitan Network, we attempt to explain their structure and mechanisms, study the reasons for their emergence and growth, and predict their future evolution. We expect that future wireless communities will be oriented toward providing broadband access to nomadic users. To this end, we have proposed that wireless network access be shared in a peer-to-peer, reciprocal manner. Thus, ubiquitous broadband Internet access can be achieved at a low cost, at least in metropolitan areas where there is abundant wireless coverage, providing an inexpensive alternative to broadband cellular services.

Banding together for bandwidth: An analysis of survey results from wireless community network participants

Using a resource mobilization framework, this study attempts to better understand the factors motivating people to join wireless community networks that enable members to share bandwidth. In addition, the research illuminates ties between this kind of peer-to-peer networking and civic engagement at a broader level. An in depth survey completed by 43 respondents from throughout Europe and North America found that participants in this movement felt a stronger sense of community, as well as were more likely to help elect local politicians and to work on local issue campaigns, after joining WiFi sharing initiatives. The study concludes with proposed policy recommendations—geared toward regulators, legislators and Internet service providers in the United States.

A security framework for wireless mesh networks

AbstractThe class of Wireless Mesh Networks (WMN) supports an ample set of applications including wireless community networks, radio access networks in rural or metropolitan areas, or wireless backbones for factory/process automation. Guaranteeing security is crucial for within these application scenarios. While contemporary wireless technologies, such as the IEEE 802.16 or the IEEE 802.11s standard, provide the basic protocol mechanisms for mesh networking, they lack in comprehensive security mechanisms. Additionally, novel security features of the above standards such as per‐link encryption break existing security solutions that rely on overhearing of the wireless channel. We close this gap by developing a holistic approach toward securing WMNs with particular focus on the network layer. We perform a threat analysis and then develop solutions (1) guaranteeing the integrity and authenticity of routing messages, (2) to locally and globally detect misbehavior of nodes in forwarding data or routing messages even for settings that do not allow for overhearing the channel, and (3) to dynamically manage reputation of nodes throughout the network. The combination of these building blocks enables to provide for secure, self‐organizing WMNs. As a proof‐of‐concept, we tailor and implement our solutions for the setting of a realistic IEEE 802.16 mesh network; we discuss the protection achieved and assess selected performance trade‐offs for the developed mechanisms. Copyright © 2010 John Wiley & Sons, Ltd.

Ammeter Interface Device and Monitoring System Based on Wireless Sensor Networks

A kind of wireless monitoring interface device based on wireless sensor networks for ammeters was proposed. Ammeters connected by UART or pulse interface to get ammeters’ real-time data. Then, an ammeter monitoring system based on wireless sensor networks (AMSBW) was designed. The system consist building-WSN and community wireless monitoring center. And user’s ammeters, ammeter wireless monitoring interface devices and building-sink nodes were included in the building-WSN; the center sink node and monitoring host were contained in community monitoring center. The functions of real-time monitoring, remote control and preventing electricity-stolen were designed in the AMSBW which had simple installation and configuration. Then a software system to test the AMSBW was exploited. At last, system’s tests results show that it could effectively achieve the goal of real-time monitoring and control ammeter.