Presence Of IEEE Research Articles

Co-existence Issue in IoT Deployment using Heterogeneous Wireless Network (HetNet): Interference Mitigation using Cognitive Radio

In today’s era of Machine-to-Machine (M2M) communication, where a tiny embedded device is having enough functionality and computational power to be network enabled for various applications aided with sensors, relays, and actuators to make Internet-of-Things (IoT) a reality. IoT is not a technology by itself rather a vision to interconnect every single piece of intelligent electronics using existing LAYER-I and II data communication standards and the internet based on OSI Layer Architecture. In the context of deployment of such IoT networks, it is imperative; a heterogeneous wireless network will be most viable for the need of different application-specific scenarios. The primary goal of this paper is to propose a Cognitive Radio (CR) Algorithm for mitigation of interference based on the analytical and empirical model of packet error rate (PER) for IEEE 802.15.4 network in the presence of IEEE 802.11 b/g/n network operating in the 2.4 GHz unlicensed industrial scientific medical (ISM) frequency band. The power spectral density (PSD) of three standards widely deployed IEEE 802.11 b/g/n are considered for determining the interference power of overlapping channels of IEEE 802.11 b/g/n. To create a test-bed for an Empirical Model Digi’s XBEE® 802.15.4 Zigbee modules is used for IEEE 802.15.4 and Intel/ Qualcomm (Atheros) WiFi Alliance adaptors are considered and IEEE 802.11 to validate the analytical model.

Co-Channel and Adjacent Channel Interference and Protection Issues for DVB-T2 and IEEE 802.22 WRAN Operation

This paper presents a study on the coexistence issue of digital terrestrial TV broadcasting and cognitive broadband access operation in the TV white spaces (TVWS). Extended measurements were performed to evaluate the protection of the existing Second generation of digital video broadcasting terrestrial standard (DVB-T2) services in the presence of IEEE 802.22 WRAN co-channel and adjacent channel interference. The absence of picture failure over 30 consecutive seconds on decoded DVB-T2 streams has been monitored to obtain the maximum tolerable level of IEEE 802.22 WRAN interference, which ensures the protection of the primary broadcast system. This paper considers practical DVB-T2 system configuration options by varying parameters of the standard, such as constellation and code rate, FFT size, pilot pattern and guard interval, and rotated constellations and compares them in terms of robustness with respect to the interference generated by IEEE 802.22 WRAN operation. The goal is to provide cognitive broadband operators in the TVWS with guidelines to optimize their network by choosing the parameters that best fit their needs in case of coexistence with DVB-T2 broadcasting services.

Avoiding collisions between IEEE 802.11 and IEEE 802.15.4 through coexistence aware clear channel assessment

More and more devices are becoming wirelessly connected. Many of these devices are operating in crowded unlicensed bands, where different wireless technologies compete for the same spectrum. A typical example is the unlicensed ISM band at 2.4 GHz, which is used by IEEE 802.11bgn, IEEE 802.15.4, and IEEE 802.15.1, among others. Each of these technologies implements appropriate Media Access Control (MAC) mechanisms to avoid packet collisions and optimize Quality of Service. Although different technologies use similar MAC mechanisms, they are not always compatible. For example, all CSMA/CA-based technologies use Clear Channel Assessment (CCA) to detect when the channel is free; however, in each case it is specifically designed to improve detection reliability of the specific technology. Unfortunately, this approach decreases the detection probability of other technologies, increasing the amount of cross-technology collisions. In this article, we introduce the concept of coexistence aware CCA (CACCA), which enables a node operating in one technology to backoff for other coexisting technologies as well. As a proof of concept, we analyze the Packet Error Rate(PER) incurred by an IEEE 802.15.4 network in the presence of IEEE 802.11bg interference, and assess the PER reduction that is achieved by using CACCA.

Performance of constrained blind adaptive DS-CDMA UWB multiuser detector in multipath channel with IEEE 802.11a interference

Ultra wideband wireless systems are supposed to coexist with other spectrally overlapping narrowband wireless systems especially IEEE 802.11a wireless LAN. Presence of narrowband interference degrades the performance of UWB. In this paper we study bit error probability performance of the constrained blind DS-CDMA UWB multi-user detection algorithms in the presence of IEEE 802.11a OFDM narrowband interference. The constrained blind adaptive algorithm is implemented using both least mean square and recursive least square algorithm and the bit error probability performance is compared with Rake matched filter receiver. The constrained blind receiver does not require spreading code knowledge of all users other than that of the user of interest. Simulation results show that the constrained blind detector cancels IEEE 802.11a interference significantly in comparison with that of the Rake matched filter in the UWB multipath channel.

Editors' opening address

Wireless Communications Systems are at the centre of a new and passionate era for telecommunications characterised, in industrial terms, by the convergence of systems and technologies, a transition towards all-IP networks, and the development of technologies with a user-centric focus. On the other hand, in terms of Research and Development, researchers are already considering other, more futuristic, aspects beyond those just mentioned, and these days hot topics include things like the Internet of the Future, and all the Post-IP perspectives that come with it. In both grounds, that is the more industrial related one and the one nearer an academic perspective, there is still a long way to go, before many of the ideas being discussed today can see the light of day as a commercial product. In this context, the International Symposium on Wireless Communication Systems (ISWCS) has positioned itself as a dynamic forum for researchers and technologists to present and discuss original ideas and contributions in all fields related to mobile and wireless communication systems. ISWSC'06, the 3rd edition, held in Valencia, Spain, on September 2006, brought together leading and enthusiastic researchers and technologists, willing to identify and discuss the future technical challenges and business opportunities arising in the path towards the realisation of ambient wireless communication networks. Besides this, it was a good forum for Ph.D. students to present their work, and exchange their ideas. The idea of setting up a special issue of a journal with the very best papers of the conference was brought up by the excellent quality of some papers presented at the conference. The objective of a special issue of this kind is always to put together, beyond the conference proceedings, the best papers in an enhanced and revised version, enabling the journal to publish good papers with timely updated information in a very short time. This special issue of Wireless Communications and Mobile Computing contains the very best papers presented at ISWCS'06. An invitation was sent to a restricted number of papers, and an additional review procedure was held, beyond the conference one. At the end, this set of six papers was accepted. The papers in this issue address some of the hot topics being investigated these days, ranging from localisation and frequency sharing to multi carrier-code division multiple access (MC-CDMA) and multiple input multiple output (MIMO). This shows that the physical layer still attracts a lot of attention, and that it still has a lot of topics to be explored. The first two papers address MIMO channels, in modelling or measurement perspectives. Matthias Pätzold and Bjørn Olav Hogstad present a model for a wideband MIMO channel based on the geometric elliptical scattering one, which can be used as a starting point for the derivation of a frequency-selective space–time channel simulator, being also useful for studying MIMO channel capacity under various propagation conditions. Michail Matthaiou et al. bring a paper on dual frequency MIMO measurements around the ISM 2.4 GHz band, in indoor environments, with initial results being promising enough, as the joint spectra seem to be remarkably similar, implying that the underlying propagation mechanisms at the considered bands are also similar. Farrukh Rashid and Athanassios Manikas present one of the papers dealing with MC-CDMA, namely on arrayed reception in space-time diffused multipath vector channels; results show that the use of a diffused channel modelling in arrayed receivers yields better bit error rate (BER) and signal to noise plus interference ratio (SNIR) performance than receivers that ignore the presence of spatial and/or temporal diffusion. The other paper on MC-CDMA, from Nguyen Tran Khoa et al., addresses frequency sharing in hotspot communications for cellular networks; it proposes an overlap in the uplink of an OFDM hotspot system to an MC-CDMA cellular one, in the same frequency band, beam-forming being applied to eliminate inter-system interference. The paper for Barbara Mavì Masini et al. also deals with the coexistence of different systems, in particular on the benefits of diversity schemes for Bluetooth coverage extension in the presence of IEEE 802.11g interference, analysing packet error and coverage probabilities, among other parameters. Finally, Joseph Shmuel Picard and Anthony Joseph Weiss present a paper addressing localisation of networks using various ranging bias models, presenting a set of iterative algorithms that cope successfully with the various bias models and provide Maximum Likelihood position estimates.

A traffic control system for IEEE 802.11 networks based on available bandwidth estimation

AbstractTo support Quality of service (QoS)‐sensitive applications like real‐time video streaming in IEEE 802.11 networks, a MAC layer extension for QoS, IEEE 802.11e, has been recently ratified as a standard. This MAC layer solution, however, addresses only the issue of prioritized access to the wireless medium and leaves such issues as QoS guarantee and admission control to the traffic control systems at the higher layers. This paper presents an IP‐layer traffic control system for IEEE 802.11 networks based on available bandwidth estimation. We build an analytical model for estimating the available bandwidth by extending an existing throughput computation model, and implement a traffic control system that provides QoS guarantees and admission control by utilizing the estimated available bandwidth information. We have conducted extensive performance evaluation of the proposed scheme via both simulations and measurements in the real test‐bed. The experiment results show that our estimation model and traffic control system work accurately and effectively in various network load conditions without IEEE 802.11e. The presence of IEEE 802.11e will allow even more efficient QoS provision, as the proposed scheme and the MAC layer QoS support will complement each other. Copyright © 2006 John Wiley & Sons, Ltd.

Improving Bluetooth performance in 802.11 interference environments

Bluetooth, with its short range and low power requirements, shows great promise in enabling the deployment of personal area networks. The ubiquity of other networking technologies such as IEEE 802.11 Local Area Networks means that wireless, short-range communication technologies such as Bluetooth will have to coexist with these 802.11 networks. We describe the design, implementation, and evaluation of a dynamic approach that improves Bluetooth performance in the presence of IEEE 802.11 traffic interference. Our approach improves Bluetooth performance in the presence of 802.11 interference traffic by almost 100% (for raw data throughput) and by 51–85% for real user applications such as file transfers.