http://jwcn.eurasipjournals.com The most accessed research articles published by EURASIP Journal on Wireless Communications and Networking 2012-05-08T00:00:00Z As the long term evolution (LTE) standard comes to an end, 3rd Generation Partnership Project is discussing further evolution of the LTE to meet the international mobile telecommunications advanced requirements, which is referred to as LTE-Advanced (LTE release 10 and beyond). This article first presents the network infrastructure of the LTE-Advanced, and then provides an in-depth overview of enabling technologies from the physical layer aspects, including carrier aggregation, advanced multiple-input multiple-output (MIMO) techniques, wireless relays, enhanced inter-cell interference coordination (eICIC), and coordinated multipoint (CoMP) transmission/reception. In particular, we describe concept and principle of each technology and elaborate important technical details. Moreover, we discuss promising study items of the LTE-Advanced for further enhancement. http://jwcn.eurasipjournals.com/content/2012/1/54 Thien-Toan Tran Yoan Shin Oh-Soon Shin EURASIP Journal on Wireless Communications and Networking 2012, null:54 2012-02-20T00:00:00Z doi:10.1186/1687-1499-2012-54 /content/figures/1687-1499-2012-54-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 54 2012-02-20T00:00:00Z XML Cognitive radio (CR) can successfully deal with the growing demand and scarcity of the wireless spectrum. To exploit limited spectrum efficiently, CR technology allows unlicensed users to access licensed spectrum bands. Since licensed users have priorities to use the bands, the unlicensed users need to continuously monitor the licensed users' activities to avoid interference and collisions. How to obtain reliable results of the licensed users' activities is the main task for spectrum sensing. Based on the sensing results, the unlicensed users should adapt their transmit powers and access strategies to protect the licensed communications. The requirement naturally presents challenges to the implementation of CR. In this article, we provide an overview of recent research achievements of including spectrum sensing, sharing techniques and the applications of CR systems. http://jwcn.eurasipjournals.com/content/2012/1/28 Lu Lu Xiangwei Zhou Uzoma Onunkwo Geoffrey Ye Li EURASIP Journal on Wireless Communications and Networking 2012, null:28 2012-01-31T00:00:00Z doi:10.1186/1687-1499-2012-28 /content/figures/1687-1499-2012-28-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 28 2012-01-31T00:00:00Z XML Multi-standard mobile devices are allowing users to enjoy higher data rates and ubiquitous connectivity. These advances are achieved on the expense of higher energy consumption requirements due to the continuous connectivity and the multiple active wireless interfaces. In this paper, we use one advantage of the multiple interfaces, namely short range communications. Mobile terminals use short range cooperative network to take advantage of the good channel quality of short range links to save energy in multi-standard mobile terminals. In this cooperative network, the combined energy of all MTs is treated as a pool of resources, which is used by all MTs in the network. Toward this end, we propose cooperation between mobile terminals using short-range technology to achieve energy savings. We conduct a quantitative numerical analysis to show the energy saving gains that can be achieved. We derive the energy gains in different use cases, considering different combinations of technologies (WiFi-WiMedia, WiMAX-WiFi and WiFi-WiFi) and different channel conditions. We show that up to 80% energy savings can be achieved when using a combination of WiMedia as short range and WiFi as long range technology, compared to using WiFi without cooperation. We also show that short range cooperation can be used to extend the lifetime of the whole network. In such scenario, terminals, which are running out of battery or low in energy, can still relay their data through other mobile terminals, even if this will result in a slight increase in the total consumption of all mobile terminals. This way, source mobile terminals with low battery level benefit from the good condition of the short range channel, extending the lifetime of their batteries. The increase in the energy consumption of the relays can hence be compensated by some kind of payment, which opens opportunities for new business models involving source mobile terminals, relays and network operators. http://jwcn.eurasipjournals.com/content/2012/1/159 Ayman Radwan Jonathan Rodriguez EURASIP Journal on Wireless Communications and Networking 2012, null:159 2012-05-02T00:00:00Z doi:10.1186/1687-1499-2012-159 /content/figures/1687-1499-2012-159-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 159 2012-05-02T00:00:00Z PDF Optimization of energy usage in Wireless Sensor Networks (WSN) has been an active research field for the last decades and various approaches have been explored. In fact, A well designed energy consumption model is the foundation for developing and evaluating a power management scheme in network of energy constrained devices such as: WSN. We are interested in developing optimal centralized power control policies for Energy Harvesting Wireless Multimedia Sensor Networks (WMSN) equipped with photovoltaic cells. We propose a new complete information Markov Decision Process (MDP) model to characterize sensor's battery discharge/recharge process and inspect the structural properties of optimal transmit policies. http://jwcn.eurasipjournals.com/content/2012/1/158 Mohammed Amine Koulali Abdellatif Kobbane Mohammed El koutbi Hamidou Tembine Jalel Ben-othman EURASIP Journal on Wireless Communications and Networking 2012, null:158 2012-05-01T00:00:00Z doi:10.1186/1687-1499-2012-158 /content/figures/1687-1499-2012-158-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 158 2012-05-01T00:00:00Z PDF Energy consumption of wireless networks is now a very important research topic and several research teams worldwide are proposing solutions for the so-called green wireless networks, i.e. energy efficient wireless networks. Although the increase of this research activity is rather recent, a great number of research papers and collaborative projects exist nowadays. We first summarise the metrics used in the related literature for performance evaluation. Then, we focus on describing the current approaches proposed by reviewing a good number of references from literature. The main research directions are presented: the component level research, where the efforts are mainly concentrated on the power amplifier section; the cell layout adaptation including the cell breathing technique and coverage extension methods like femtocells and relays; in addition, we also include the radio resource management (RRM) and the Cognitive radio (CR) into the studied approaches. These methods are analysed, compared, classified and then a framework of classification & integration is proposed. We finally describe some major collaborative projects dedicated to this topic. http://jwcn.eurasipjournals.com/content/2012/1/142 Luis Suarez Loutfi Nuaymi Jean-Marie Bonnin EURASIP Journal on Wireless Communications and Networking 2012, null:142 2012-04-13T00:00:00Z doi:10.1186/1687-1499-2012-142 /content/figures/1687-1499-2012-142-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 142 2012-04-13T00:00:00Z PDF In this article, we show that the non-ideal Radio-Frequency (RF) front-ends have to be corrected in order to contribute in a Green radio development. In fact, the effects of typical RF imperfections, like nonlinearities, carrier frequency offsets, and IQ imbalances, can be compensated for, when digital correction algorithms are applied. Such algorithms enable Green applications (e.g., Orthogonal Frequency Division Multiple Access for the uplink) despite a restrictive RF imperfection, or allow a less constrained hardware design, which reduces the chip area and the number of components (Green design) or facilitate the reduction of spectral pollution and of power consumption (Green transmission). So, we propose to implement these correction methods to compensate for the damaging effects of RF imperfections in mind of a Green issue. http://jwcn.eurasipjournals.com/content/2012/1/146 Myriam Ariaudo Inbar Fijalkow Jean-Luc Gautier Mathilde Brandon Babar Aziz Borislav Milevsky EURASIP Journal on Wireless Communications and Networking 2012, null:146 2012-04-18T00:00:00Z doi:10.1186/1687-1499-2012-146 /content/figures/1687-1499-2012-146-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 146 2012-04-18T00:00:00Z PDF Sequential decoding can achieve a very low computational complexity and short decoding delay when the signal-to-noise ratio (SNR) is relatively high. In this paper, a low-complexity high-throughput decoding architecture based on a sequential decoding algorithm is proposed for convolutional codes. Parallel Fano decoders are scheduled to the codewords in parallel input buffers according to buffer occupancy, so that the processing capabilities of the Fano decoders can be fully utilized, resulting in high decoding throughput. A discrete time Markov chain (DTMC) model is proposed to analyse the decoding architecture. The relationship between the input data rate, the clock speed of the decoder and the input buffer size can be easily established via the DTMC model. Different scheduling schemes and decoding modes are proposed and compared. The novel high-throughput decoding architecture is shown to incur 3%--10% of the computational complexity of Viterbi decoding at a relatively high SNR. http://jwcn.eurasipjournals.com/content/2012/1/151 Ran Xu Kevin Morris Graeme Woodward Taskin Kocak EURASIP Journal on Wireless Communications and Networking 2012, null:151 2012-04-23T00:00:00Z doi:10.1186/1687-1499-2012-151 /content/figures/1687-1499-2012-151-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 151 2012-04-23T00:00:00Z PDF In cellular communication systems with frequency reuse factor of one, user terminals(UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount of required feedback. However, it is difficult to achieve a corresponding reduction on the backhaul related to the precoding weights, when a linear zero forcing beamforming technique is used. In this work, particle swarm optimization is proposed as a tool to design the precoding weights under feedback and backhaul constraints related to PJP.The precoder obtained with the objective of weighted interference minimization allows some multiuser interference in the system, and it is shown to improve the sum rate by 66% compared to a conventional zero forcing approach, for those users experiencing low signal to interference plus noise ratio. http://jwcn.eurasipjournals.com/content/2012/1/163 Tilak Rajesh Lakshmana Carmen Botella Tommy Svensson EURASIP Journal on Wireless Communications and Networking 2012, null:163 2012-05-08T00:00:00Z doi:10.1186/1687-1499-2012-163 /content/figures/1687-1499-2012-163-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 163 2012-05-08T00:00:00Z PDF The explosions of Internet of Things industry have been bringing more and more smart device into business and people's daily life. This creates new opportunities to build applications that better integrate real-time state of the physical world and requires agility for the software to accommodate customers' requirements. Nevertheless, devices are usually provided by different manufacturers, and applications are independently constructed based on their own infrastructures with little interoperability. Web of Things concept have enabled the interoperability between devices by RESTful web service in a light-weight way, however, it make less efforts to discuss how to integrate device into complex business environment. Service Oriented Architecture and Business Process Management approach are becoming applicable to embedded real-world devices and provide flexible service composition. However, it is based on WS-* web service specification which is too heavy and complex for device and not compatible to RESTful style. In such situation, to integrate device into business application with simple and provide agility composition of service based on device are significant challenges. We propose a Web-based Two-layered Integration Framework that enables smart device to integrate with each other via light-weight interface and other back-end applications into agile business process. A real-life use case on elderly care is studied in detail based on the framework. http://jwcn.eurasipjournals.com/content/2012/1/150 Zhenyu Wu Timo Itala Tingan Tang Chunhong Zhang Yang Ji Matti Hamalainen Yunjie Liu EURASIP Journal on Wireless Communications and Networking 2012, null:150 2012-04-23T00:00:00Z doi:10.1186/1687-1499-2012-150 /content/figures/1687-1499-2012-150-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 150 2012-04-23T00:00:00Z PDF Multi-Radio Multi-Channel (MRMC) Wireless Mesh Networks (WMNs) achieve higher throughput using multiple simultaneous transmissions and receptions. However, due to limited number of non-overlapping channels, such networks suffer from co-channel interference, which degrades their performance. To mitigate co-channel interference, effective channel assignment algorithms (CAAs) are desired. In this paper, we propose a novel CAA, Topology-controlled Interference-aware Channel-assignment Algorithm (TICA), for MRMC WMNs. This algorithm uses topology control based on power control to assign channels to multi-radio mesh routers such that co-channel interference is minimized, network throughput is maximized, and network connectivity is guaranteed. We further propose to use two-way interference-range edge coloring, and call the improved algorithm Enhanced TICA (e-TICA), which improves the fairness among flows in the network. However, the presence of relatively long links in some topologies leads to conflicting channel assignments due to their high interference range. To address this issue, we propose to utilize minimum spanning tree rooted at the gateway to reduce conflicting channels, and in turn, improve medium access fairness among the mesh nodes. We call the improved algorithm e-TICA version 2 (e-TICA2). We evaluate the performance of the proposed CAAs using simulations in NS2. We show that TICA significantly outperforms the Common Channel Assignment scheme [1] in terms of network throughput, and e-TICA and e-TICA2 achieve better fairness among traffic flows as compared to TICA. It is also shown that e-TICA2 leads to improved network throughput, as compared to TICA and e-TICA. http://jwcn.eurasipjournals.com/content/2012/1/155 Aizaz Chaudhry Nazia Ahmad Roshdy Hafez EURASIP Journal on Wireless Communications and Networking 2012, null:155 2012-04-30T00:00:00Z doi:10.1186/1687-1499-2012-155 /content/figures/1687-1499-2012-155-toc.gif EURASIP Journal on Wireless Communications and Networking 1687-1499 ${item.volume} 155 2012-04-30T00:00:00Z PDF