Performance analysis of contention based bandwidth request mechanisms in WiMAX networks

This article is posted here with the permission of IEEE. The official version can be obtained from the DOI below - Copyright @ 2010 IEEEWiMAX networks have received wide attention as they support high data rate access and amazing ubiquitous connectivity with great quality-of-service (QoS) capabilities. In order to support QoS, bandwidth request (BW-REQ) mechanisms are suggested in the WiMAX standard for resource reservation, in which subscriber stations send BW-REQs to a base station which can grant or reject the requests according to the available radio resources. In this paper we propose a new analytical model for the performance analysis of various contention based bandwidth request mechanisms, including grouping and no-grouping schemes, as suggested in the WiMAX standard. Our analytical model covers both unsaturated and saturated traffic load conditions in both error-free and error-prone wireless channels. The accuracy of this model is verified by various simulation results. Our results show that the grouping mechanism outperforms the no-grouping mechanism when the system load is high, but it is not preferable when the system load is light. The channel noise degrades the performance of both throughput and delay.This work was supported by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/G070350/1 and by the Brunel University’s BRIEF Award

Simulation of Relay modes in IEEE 802.16j Mobile Multi-hop Relay (MMR) WIMAX Networks

Two different relay modes are defined in IEEE 802.16j WIMAX standard: transparent mode and non-transparent mode. The non transparent mode is used to extend the coverage area of base stations, where low cost relay station of equal capacity as that of base station is placed at suitable position. Time taken to accept mobile stations and Bandwidth allocation are main problems in non transparent mode. In this we have studied the IEEE 802.16j standard multi hop relay WIMAX networks. We have used relay stations to extend the coverage of base stations. We have also analyzed the throughput between mobile stations with in the coverage area and outside coverage area of base stations. We have simulated the IEEE 802.16j transparent and non transparent mode multi hop WIMAX relay networks using NCTUns Too

Relay Technologies in IEEE 802.16j Mobile Multi-hop Relay (MMR) Networks

IEEE 802.16 standard is created to compete with cable access networks. In the beginning end users are immobile and have a line of sight with base station, now it moved to mobile non line of sight (NLOS) with the new standard IEEE 802.16e and IEEE 802.16j. The new IEEE 802.16j standard which is an amendment to IEEE 802.16e is mobile multi hop relay (MMR) specification for wireless networks. This paper discusses relay modes, relay transmission schemes and relay pairing schemes of IEEE 802.16j. Relay technologies such as transparent relay modes, non transparent relay mode, relay pairing schemes such as centralized relay pairing schemes, distributed relay pairing scheme, characterises of relay based networks such as throughput enhancement, capacity increase, cost reduction , relay techniques such as time domain frequency domain relay techniques and relay placement are also discussed in this paper. The paper also discusses about integration of IEEE 802.16j with IEEE 802.11. Keywords: IEEE 802.16j, Relay pairing schemes, relay techniques, Relay modes, WIMAX, NCTUns, et

Adjusting WiMAX for a Dedicated Surveillance Network

WiMAX (Worldwide Interoperability for Microwave Access) devices have been used widely in the market. WiMAX-based video surveillance products have also been available. The acceptance of WiMAX in the market, as well as the availability of WiMAX products, contributes to the possibility of implementing it for dedicated video surveillance application. However, since WiMAX is designed to accommodate various applications with different quality of service (QoS) requirements, WiMAX–based dedicated surveillance network may not achieve optimum performance, as all SSs generate the same QoS requirements. The scheduler cannot implement traffic type priority; therefore, service classification does not work as expected. This paper proposes WiMAX adjustment to transform a multi-purpose WiMAX network into a network dedicated to video surveillance. NS-2 simulations show that the proposed adjustment is able to deliver low delay and high quality video surveillance.DOI:http://dx.doi.org/10.11591/ijece.v3i4.318

Wireless Technologies for IoT in Smart Cities

[EN] As cities continue to grow, numerous initiatives for Smart Cities are being conducted. The concept of Smart City encompasses several concepts being governance, economy, management, infrastructure, technology and people. This means that a Smart City can have different communication needs. Wireless technologies such as WiFi, ZigBee, Bluetooth, WiMax, 4G or LTE (Long Term Evolution) have presented themselves as solutions to the communication needs of Smart City initiatives. However, as most of them employ unlicensed bands, interference and coexistence problems are increasing. In this paper, the wireless technologies available nowadays for IoT (Internet of Things) in Smart Cities are presented. Our contribution is a review of wireless technologies, their comparison and the problems that difficult coexistence among them. In order to do so, the characteristics and adequacy of wireless technologies to each domain are considered. The problems derived of over-crowded unlicensed spectrum and coexistence difficulties among each technology are discussed as well. Finally, power consumption concerns are addressed.García-García, L.; Jimenez, JM.; Abdullah, MTA.; Lloret, J. (2018). Wireless Technologies for IoT in Smart Cities. Network Protocols and Algorithms. 10(1):23-64. doi:10.5296/npa.v10i1.12798S236410

Performance Analysis of Best-effort Service in Saturated IEEE 802.16 Networks

The IEEE 802.16 standard is a promising technology for the fourth-generation mobile networks and is being actively promoted by the WiMAX Forum, an industry-led consortium. Among the various service classes supported in the standard, best-effort service is expected to be the major service class subscribed by users due to its operation simplicity and lower charging rate compared with other service classes. In this paper, we investigate the throughput and packet access delay performance of the besteffort service using contention-based bandwidth request mechanism in a saturated 802.16 network. In particular, we develop a simple fixed point analysis to approximate the failure probability of a bandwidth request and derive analytical expressions for network throughput and packet access delay. Furthermore, the uniqueness of the fixed point is established. The accuracy of the analytical model is validated by comparing with simulation over a wide range of operating conditions. The implication of various different parameter configurations on the system performance is investigated using the analytical model. The utility of the model is further demonstrated by finding the maximum achievable throughput and obtaining its corresponding optimal initial contention window. Performance Analysis of Best-effort Service i

Design of Wireless Communication Networks for Cyber-Physical Systems with Application to Smart Grid

Cyber-Physical Systems (CPS) are the next generation of engineered systems in which computing, communication, and control technologies are tightly integrated. On one hand, CPS are generally large with components spatially distributed in physical world that has lots of dynamics; on the other hand, CPS are connected, and must be robust and responsive. Smart electric grid, smart transportation system are examples of emerging CPS that have significant and far-reaching impact on our daily life. In this dissertation, we design wireless communication system for CPS. To make CPS robust and responsive, it is critical to have a communication subsystem that is reliable, adaptive, and scalable. Our design uses a layered structure, which includes physical layer, multiple access layer, network layer, and application layer. Emphases are placed on multiple access and network layer. At multiple access layer, we have designed three approaches, namely compressed multiple access, sample-contention multiple access, and prioritized multiple access, for reliable and selective multiple access. At network layer, we focus on the problem of creating reliable route, with service interruption anticipated. We propose two methods: the first method is a centralized one that creates backup path around zones posing high interruption risk; the other method is a distributed one that utilizes Ant Colony Optimization (ACO) and positive feedback, and is able to update multipath dynamically. Applications are treated as subscribers to the data service provided by the communication system. Their data quality requirements and Quality of Service (QoS) feedback are incorporated into cross-layer optimization in our design. We have evaluated our design through both simulation and testbed. Our design demonstrates desired reliability, scalability and timeliness in data transmission. Performance gain is observed over conventional approaches as such random access

Études des systèmes de communications sans-fil dans un environnement rural difficile

Les systèmes de communication sans fil, ayant de nombreux avantages pour les zones rurales, peuvent aider la population à bien s'y établir au lieu de déménager vers les centres urbains, accentuant ainsi les problèmes d’embouteillage, de pollution et d’habitation. Pour une planification et un déploiement efficace de ces systèmes, l'atténuation du signal radio et la réussite des liens d’accès doivent être envisagées. Ce travail s’intéresse à la provision d’accès Internet sans fil dans le contexte rural canadien caractérisé par sa végétation dense et ses variations climatiques extrêmes vu que les solutions existantes sont plus concentrées sur les zones urbaines. Pour cela, nous étudions plusieurs cas d’environnements difficiles affectant les performances des systèmes de communication. Ensuite, nous comparons les systèmes de communication sans fil les plus connus. Le réseau sans fil fixe utilisant le Wi-Fi ayant l’option de longue portée est choisi pour fournir les communications aux zones rurales. De plus, nous évaluons l'atténuation du signal radio, car les modèles existants sont conçus, en majorité, pour les technologies mobiles en zones urbaines. Puis, nous concevons un nouveau modèle empirique pour les pertes de propagation. Des approches utilisant l’apprentissage automatique sont ensuite proposées, afin de prédire le succès des liens sans fil, d’optimiser le choix des points d'accès et d’établir les limites de validité des paramètres des liens sans fil fiables. Les solutions proposées font preuve de précision (jusqu’à 94 % et 8 dB RMSE) et de simplicité, tout en considérant une multitude de paramètres difficiles à prendre en compte tous ensemble avec les solutions classiques existantes. Les approches proposées requièrent des données fiables qui sont généralement difficiles à acquérir. Dans notre cas, les données de DIGICOM, un fournisseur Internet sans fil en zone rurale canadien, sont utilisées. Wireless communication systems have many advantages for rural areas, as they can help people settle comfortably and conveniently in these regions instead of relocating to urban centers causing various overcrowding, habitation, and pollution problems. For effective planning and deployment of these technologies, the attenuation of the radio signal and the success of radio links must be precisely predicted. This work examines the provision of wireless internet access in the Canadian rural context, characterized by its dense vegetation and its extreme climatic variations, since existing solutions are more focused on urban areas. Hence, we study several cases of difficult environments affecting the performances of communication systems. Then, we compare the best-known wireless communication systems. The fixed wireless network using Wi-Fi, having the long-range option, is chosen to provide wireless access to rural areas. Moreover, we evaluate the attenuation of the radio signal, since the existing path loss models are generally designed for mobile technologies in urban areas. Then, we design a new path loss empirical model. Several approaches are then proposed by using machine learning to predict the success of wireless links, optimize the choice of access points and establish the validity limits for the pertinent parameters of reliable wireless connections. The proposed solutions are characterized by their accuracy (up to 94% and 8 dB RMSE) and simplicity while considering a wide range of parameters that are difficult to consider all together with conventional solutions. These approaches require reliable data, which is generally difficult to acquire. In our case, the dataset from DIGICOM, a rural Canadian wireless internet service provider, is used

A Novel Approach for Implementing Worldwide Interoperability for Microwave Access for Video Surveillance

Video surveillance applications have experienced an increase in demand over the last decade. Surveillance systems can easily be found in places such as commercial offices, banks and traffic intersections, parks and recreational areas. Surveillance applications have the potential to be implemented on a WiMAX (Worldwide Interoperability for Microwave Access) network. Moreover, WiMAX devices have been used widely in the market and WiMAX-based video surveillance products have also been available. As a radio technology, WiMAX is a wireless broadband system that offers greater capacity than WiFi networks and wider coverage than cellular networks. The acceptance of WiMAX in the market, the availability of WiMAX products and its technology excellence, contribute to the possibility of implementing it for surveillance application. However, since WiMAX is designed to accommodate various applications with different quality of service (QoS) requirements, dedicated surveillance network implementation of WiMAX may not achieve optimum performance, as all Subscriber Stations (SSs) generate the same QoS requirements. In the medium access (MAC) layer, this thesis proposes a bandwidth allocation scheme that considers the QoS uniformity of the traffic sources. The proposed bandwidth allocation scheme comprises a simplified bandwidth allocation architecture, a packet-aware bandwidth request mechanism and packet-aware scheduling algorithms. The simplified architecture maximizes resources in the Base Station (BS), deactivates unnecessary services and minimizes the processing delay. The proposed bandwidth request mechanism reduces bandwidth grant and transmission delays. The proposed scheduling algorithms prioritize bandwidth granting access to a request that contains important packet(s). The proposed methods in the MAC layer are designed to be applied to existing devices in the market, without the necessity to change hardware. The transport protocol should be able to deliver video with sufficient quality while maintaining low delay connectivity. The proposed transport layer protocol is therefore designed to improve the existing user datagram protocol (UDP) performance by retransmitting packet loss selectively to increase the received video quality, and utilizing MAC support to achieve low delay connectivity. In order to overcome the limitations of the lower layers, this thesis employs a rateless code instead of transport layer redundancy in the application layer. Moreover, this thesis proposes post-decoding error concealment techniques as the last means to overcome packet loss. To evaluate the performances of the proposed methods, simulations are carried out using NS-2 simulator on Linux platform. The proposed methods are compared to existing works to measure their effectiveness. To facilitate the implementation of the transport layer protocols in practical scenarios, UDP packet modification is applied for each transport layer protocol.Indonesian Directorate General of Higher Education (DGHE/DIKTI

Assessing the sustainability performance of inter-urban intelligent transport

The implementation of ITS to increase the efficiency of saturated highways has become increasingly prevalent. It is a high level objective for many international governments and operators that highways should be managed in a way that is both sustainable i.e. environmental, social and economically sound and supportive of a Low-Carbon-Energy Future. Some clarity is therefore needed to understand how Intelligent Transport Systems perform within the constraints of that objective. This thesis describes the development of performance criteria that reflect the contributions of Information Communication Technology (ICT) emissions, vehicle emissions and the embedded carbon within the physical transport infrastructure that typically comprises three types of Intelligent Transport System. Active Traffic Management, Intelligent Speed Adaptation and the Automated Highway System are a collection of systems designed to transform the road network into a highly efficient and congestion free transport solution and all possess varying levels of uncertainty in terms of sustainability performance. The performance criteria form part of a new framework methodology ‘EnvFUSION’ (Environmental Fusion for ITS) outlined here. An attributional LCA and c-LCA (consequential lifecycle assessment) are both undertaken which forms part of a data fusion process using data from various sources. The models forecast improvements for the three ITS technologies in-line with social acceptability, economic profitability and major carbon reduction scenarios up to 2050 on one of the UK's most congested highways. Analytical Hierarchy Process and Dempster-Shafer theory are used to weight criteria which form part of an Intelligent Transport Sustainability Index. Overall performance is then synthesized. Results indicate that there will be a substantial increase in socio-economic and emissions benefits, provided that the policies are in place and targets are reached which would otherwise delay their realisation. To conclude, an integrated strategic performance management framework is proposed which performs socio-technical comparisons of four key performance areas between ITS schemes in order to identify energy and emission hotspots