Online ISSN
1751-8636
Print ISSN
1751-8628
IET Communications
Volume 5, Issue 8, 20 May 2011
Volumes & issues:
Volume 5, Issue 8
20 May 2011
-
- Author(s): H. Samimi
- Source: IET Communications, Volume 5, Issue 8, p. 1039 –1043
- DOI: 10.1049/iet-com.2010.0075
- Type: Article
- + Show details - Hide details
-
p.
1039
–1043
(5)
Transmit laser selection (TLS) diversity scheme has been proposed recently for free-space optical communication systems and its bit error rate (BER) performance has been investigated over K-distributed turbulence channels based on lengthy simulations. Moreover, for a limiting case of strong turbulence conditions that have been modelled by negative exponential distribution, a closed-form expression for the average BER has been presented in the open technical literature. In this study, first a novel approximate analytical expression is derived for the probability density function (PDF) of the resulting channel irradiance corresponding to a TLS diversity scheme over the K channel. The approximated PDF accurately estimates the statistics of the channel irradiance over a wide range of channel conditions. Then, based on the derived PDF, an analytical closed-form expression is presented for the average BER, which can be used to estimates the BER of the system very accurately over K-distributed turbulence channels without resorting to lengthy simulations. Additionally, based on the derived analytical results, the effect of using laser pulse shape with increased peak-to-average optical power ratio on the system performance is investigated. Numerical results are further demonstrated to confirm the analytical results. - Author(s): M. Dashevskiy and Z. Luo
- Source: IET Communications, Volume 5, Issue 8, p. 1044 –1051
- DOI: 10.1049/iet-com.2010.0121
- Type: Article
- + Show details - Hide details
-
p.
1044
–1051
(8)
Time series prediction has many important real applications such as network resource management and quality-of-service assurance. Many different techniques have been developed to deal with time series predictions, for example, the Box–Jenkins approach and machine learning. In this study, the authors focus on the problem of time series prediction with performance guarantees and describe two machine-learning techniques, namely prediction with expert advice and conformal predictors. The authors investigate the application of these techniques to network traffic demand and propose a novel way of combining these two techniques to provide performance guarantee on predictions. The method is generic and the authors demonstrate this approach by carrying out extensive experiments on both artificially generated data and publicly available network traffic demand datasets. Empirical results show that the proposed method can increase the performance of the prediction system. - Author(s): Q. Lu ; T. Peng ; C. Hu ; W. Wang
- Source: IET Communications, Volume 5, Issue 8, p. 1052 –1059
- DOI: 10.1049/iet-com.2010.0685
- Type: Article
- + Show details - Hide details
-
p.
1052
–1059
(8)
The convergence of non-cooperative distributed power control in Gaussian interference channel is analysed in this study. Firstly, the existing distributed power control schemes are categorised as two types: gradient projection type and non-linear type, according to the iterative steps. A unified mathematical formulation is then provided for each type. The objective is extended from rate maximisation, which has been studied a lot in iterative water-filling game, to more general form of utility maximisation. Based on it, a set of sufficient conditions are derived for each type of the schemes, guaranteeing the uniqueness of the fixed point and the global convergence in a totally asynchronous manner. These convergence requirements can be interpreted as different degree of separation, according to the concrete form of utility function. To get insight into the derived convergence conditions, some numerical results are presented in the end. - Author(s): W. Nie ; H. Wang ; N. Xiong
- Source: IET Communications, Volume 5, Issue 8, p. 1060 –1067
- DOI: 10.1049/iet-com.2010.0770
- Type: Article
- + Show details - Hide details
-
p.
1060
–1067
(8)
As WiMAX achieves increasing deployment, the large overhead in its uplink scheduling when providing real-time services has become a major challenge. In this study, the authors present effective, low-overhead scheduling algorithms for WiMAX uplink scheduling. The authors adaptively predict users' load and select a small set of active users to be served. This addresses the major source of overhead in WiMAX uplink scheduling: the Markovian arrival process information elements (IEs) and media access control layer (MAC) service data unit (SDUs) subheader overheads grow with the number of active users. The authors introduce additional novel techniques, including piggybacking, to reduce MAC overhead. The authors implement their algorithms and conduct extensive evaluations. The results show that their algorithms not only provide quality-of-service guarantees, but also substantially reduce the scheduling overhead compared with existing schemes. - Author(s): C. Shen and H. Yu
- Source: IET Communications, Volume 5, Issue 8, p. 1068 –1072
- DOI: 10.1049/iet-com.2010.0671
- Type: Article
- + Show details - Hide details
-
p.
1068
–1072
(5)
A simple algorithm that aligns signals of different arrival times on a randomly distributed sensor array is presented. For each sensor, the new algorithm makes use of the array combined output except for self-signal as reference, and the compensative delay value is determined with the reference to improve the performance of time-delay estimator. The theoretical convergence characteristics and the relative implementations in practice are also analysed. Furthermore, the study adopts time-delay estimator with cross-correlation plus Lagrange interpolation in common use to verify the validity and the performance of the proposed algorithm. Simulation results show that the algorithm achieves a substantial performance improvement over the conventional estimator with a single fixed reference owing to optimal usage of the mutual information between the sensors, especially at low signal-to-noise ratio (SNR) values. - Author(s): L. Zheng ; J. Liu ; C. Zhai ; H. Chen ; Y. Zhou
- Source: IET Communications, Volume 5, Issue 8, p. 1073 –1082
- DOI: 10.1049/iet-com.2010.0608
- Type: Article
- + Show details - Hide details
-
p.
1073
–1082
(10)
Based on the selection decode-and-forward cooperative protocol, a novel distributed quality of service (QoS) aware routing algorithm is proposed to minimise the total energy consumption of the wireless links from the cross-layer design perspective. For the non-cooperative and cooperative truncated automatic repeat request schemes, performance of packet error rate with M-PSK and M-QAM symbols over Nakagami-m fading channels is first analysed, and then system throughput is derived. Subsequently, transmission power is optimally allocated while satisfying the end-to-end throughput requirement. With polynomial complexity, using the traditional distributed shortest path algorithm, the route that includes a cascade of non-cooperative and cooperative building blocks and has the minimal total link cost (defined as the average total consumed power) is constructed to bear the information flow. In contrast to the previous non-cooperative routing schemes, this cooperative routing algorithm can significantly reduce the total energy consumption. - Author(s): N. Mokari and K. Navaie
- Source: IET Communications, Volume 5, Issue 8, p. 1083 –1089
- DOI: 10.1049/iet-com.2010.0319
- Type: Article
- + Show details - Hide details
-
p.
1083
–1089
(7)
In this study, the authors formulate the optimal radio resource allocation for OFDM-based relay networks with heterogeneous delay requirements. The authors consider streaming traffic that requires a maximum guaranteed average delay and elastic traffic with flexible rate requirements. The main objective is to maximise the total transmission rate of elastic users, while average delay constraint for streaming traffic is satisfied. In the proposed formulation we also consider transmit power constraint for the base station as well as each relay. The authors then propose an algorithm based on dual approach to find the optimum subcarrier, relay assignment and power allocation. Using simulations, the authors evaluate the impact of streaming traffic on the total rate of elastic users for different number of relays and various power constraints. - Author(s): G. Yang ; H. Hu ; L. Rong ; Y. Du
- Source: IET Communications, Volume 5, Issue 8, p. 1090 –1095
- DOI: 10.1049/iet-com.2010.0281
- Type: Article
- + Show details - Hide details
-
p.
1090
–1095
(6)
In this research, the authors study the impact of a controlling parameter on system performances of our previously proposed heuristic channel-aware scheduling algorithm. In addition, parameter optimisation for a combined performance measure is also discussed. The investigation is carried out through numerical simulations via ns-2. When compared with other algorithms, the proposed algorithm uniformly shows the best performance, with the performance gain being more evident for bad channel. The findings are useful for system designers. - Author(s): H.A. Ngo ; T.D. Nguyen ; L. Hanzo
- Source: IET Communications, Volume 5, Issue 8, p. 1096 –1106
- DOI: 10.1049/iet-com.2010.0128
- Type: Article
- + Show details - Hide details
-
p.
1096
–1106
(11)
Systematic Luby transform (SLT) codes constitute rateless codes, which are capable of adaptively adjusting their code rate depending on the channel quality without any explicit channel state information (CSI) at the transmitters. SLTs are also suitable for space time collaboration-aided relay networks. In this study, an iterative decoding-aided SLT scheme is combined with 16 quadrature amplitude modulation (QAM) transmission in a wireless relay-aided network. The bit error ratio (BER) results and extrinsic information transfer (EXIT) charts are provided to evaluate the performance of the proposed scheme. The simulation results show that the proposed scheme using amplify-and-forward (AF) relaying achieves a 2.5 dB gain at a BER of 10−5, while the attainable improvement is nearly 6 dB for decode-and-forward (DF) relaying, compared to the non-iterative detection scheme operating without the relay's assistance. Moreover, the AF relaying-aided SLT coded 16-QAM scheme is more beneficial, when the relay station is close to the source. By contrast, the DF relaying performs best near the mid-point between the source and the destination. Additionally, a modified Hybrid Automatic-Repeat-reQuest (HARQ) protocol using incremental redundancy is applied along with the SLT-coded 16-QAM scheme in order to enhance the achievable throughput and energy efficiency of cooperative networks. This arrangement reduces the total transmit power by about 5%, compared to the classic HARQ scheme. - Author(s): X. Liu
- Source: IET Communications, Volume 5, Issue 8, p. 1107 –1112
- DOI: 10.1049/iet-com.2010.0604
- Type: Article
- + Show details - Hide details
-
p.
1107
–1112
(6)
In the reported studies of optical inter-satellite communications, the transmitter sways in the azimuth and elevation axes are always assumed being uncorrelated. In the present work, the analysis is extended to the correlated case. Theoretically, this study shows that the instantaneous signal-to-noise ratio follows the log-square-Hoyt distribution. Based on this model, it is further shown that the outage probability can be minimised, subject to a specified transmitter power, by appropriately adjusting some system parameters such as the transmitter gain. - Author(s): M. Atamanesh and F. Farzaneh
- Source: IET Communications, Volume 5, Issue 8, p. 1113 –1122
- DOI: 10.1049/iet-com.2010.0393
- Type: Article
- + Show details - Hide details
-
p.
1113
–1122
(10)
The vertical plane launching ray tracing method has been applied for a real urban scenario and the delay characteristics of received signals in the overall coverage area have been extracted. Using these parameters, an equivalent channel impulse response (ECIR) has been introduced for the overall coverage area. For an orthogonal frequency division multiplexing system, the optimum guard interval, which maximises the number of points with symbol error rate less than a threshold, has been simulated. Using the defined ECIR, the optimum guard interval could be analytically extracted. - Author(s): R.K. Jeyachitra and R. Sukanesh
- Source: IET Communications, Volume 5, Issue 8, p. 1123 –1128
- DOI: 10.1049/iet-com.2010.0435
- Type: Article
- + Show details - Hide details
-
p.
1123
–1128
(6)
The authors propose a highly selective and tunable microwave photonic filter based on parallel Fabry–Pérot filters with fibre Bragg gratings for delay. The filter is suitable for noise and interference suppression in universal mobile telecommunications system (UMTS) base stations. Simulation results demonstrate the feasibility of these filters in UMTS applications, and also show flexibility in their frequency response. Tunability of the filter has been employed for UMTS channel selection and grating length has been tuned in order to achieve appropriate delay. The filter provides a very high selective performance (in the frequency range of 1937–1976 MHz and a very high-quality factor of 494) with very high sidelobe suppression (>36 dB) in the stop band with lesser number of components. Tunability and reconfigurability of the proposed filter was obtained by changing the grating length. In this way, easy implementation of simple, compact and cost-effective filter has been demonstrated. - Author(s): Y.S. Jeong ; Y.J. Chung ; J.H. Park
- Source: IET Communications, Volume 5, Issue 8, p. 1129 –1137
- DOI: 10.1049/iet-com.2010.0723
- Type: Article
- + Show details - Hide details
-
p.
1129
–1137
(9)
A wireless sensor network (WSN) consists of spatially distributed autonomous sensors that cooperatively monitor physical or environmental conditions such as temperature, sound, vibration, pressure, motion and pollutants. WSNs are currently utilised in various and different types of WSN simulators have been developed to visually depict the coverage, energy consumption status and expected lifetime of WSN sensors. In particular, owing to the importance of low energy movement design for efficient energy consumption, devices that can design and verify the efficiency of packets are being developed. Therefore, this study suggests a coverage visualisation technique for a sensor node; this technique is based on an existing binary model that uses the detection rate of nodes portrayed on a heat map. In addition to coverage visualisation, the visualisation technique can be used to predict the energy lifetime of a node. The simulator that can verify visualisation techniques for efficient coverage visualisation and energy lifetime prediction has been designed and implemented. This simulator, which the authors have named current reduction state observer on WSN device (CROWD), performs sensor network simulation using a virtual sensor network and multi-mobile objects. CROWD also shows the detection rate of sensors on a heat map. - Author(s): Y. Zhao ; J. Zhang ; H. Zhang ; W. Gu ; Y. Ji
- Source: IET Communications, Volume 5, Issue 8, p. 1138 –1146
- DOI: 10.1049/iet-com.2010.0618
- Type: Article
- + Show details - Hide details
-
p.
1138
–1146
(9)
With the emergence of various broadband services, a lot of bandwidth fragments will be generated during the operation of services being mapped into optical channels, which will waste too many bandwidth resources and decrease the transmission performance of optical networks. Traffic grooming strategy in dynamic optical networks can optimise the utilisation of bandwidth resources and reduce the blocking probability. However, in the distributed control plane of automated switched optical networks, all the traffic grooming strategies are implemented in each control node, and resource collision will still occur because the same link resource may be used by two path computation requests or traffic engineering information flooded by open shortest path first-traffic engineering protocol may be not synchronous at each control node or signalling delay time is too long. To reduce the collision of resource, a unified control plane is designed based on path computation element (PCE) for Internet protocol over wavelength division multiplexing networks, and a novel PCE-based traffic grooming strategy is proposed in the framework of unified control plane. Based on this strategy, four PCE-based traffic grooming algorithms are proposed and compared with the distributed traffic grooming strategy without PCE on a simulation platform implemented using disperse event simulation tool OMNET++. - Author(s): J.J.P.C. Rodrigues ; F.M.R. Sabino ; L. Zhou
- Source: IET Communications, Volume 5, Issue 8, p. 1147 –1154
- DOI: 10.1049/iet-com.2010.0409
- Type: Article
- + Show details - Hide details
-
p.
1147
–1154
(8)
The emergence of Web 2.0 has transformed the web into a more dynamic and interactive environment, offering a set of tools that enhance contact and collaboration between users. Several applications, such as online social networks, wikis and blogs, support such Web vision. This study elaborates on the tremendous potential of online social networks to enhance e-learning experience, creating an atmosphere of cooperation and easy interaction among users (teachers and students). A traditional learning content management system is rigid in nature, limiting the student learning process. As a result, the concepts of community, relationship and interaction among users are needed to overcome its limitations. This contribution addresses the evolution from the traditional content learning management systems to a new conceptual learning approach, using personal learning environments. Improving the learning experience using an e-learning platform is the main motivation for this work. Then, several online social networks-related modules were proposed for an e-learning platform, called personal learning environment box, creating a space for sharing and collaboration turning students more active in shaping their learning process. The proposal was evaluated through a utility survey to users, after four months term of system usage, and the results are extremely promising. - Author(s): N. Taşpınar ; D. Karaboǧa ; M. Yıldırım ; B. Akay
- Source: IET Communications, Volume 5, Issue 8, p. 1155 –1162
- DOI: 10.1049/iet-com.2010.0379
- Type: Article
- + Show details - Hide details
-
p.
1155
–1162
(8)
Multicarrier code division multiple access (MC-CDMA) is a very promising system for wireless communication. However, MC-CDMA signals have a high peak-to-average power ratio (PAPR), which causes signal distortion because of the use of a high-power amplifier (HPA) in the transmitter. Partial transmit sequences (PTSs) represent one of the most attractive PAPR reduction methods, but its high computational complexity in finding the optimal phase vector impedes practical implementation. In this paper, we propose a PTS based on an artificial bee colony (ABC) algorithm scheme (ABC-PTS) to reduce the computational complexity of the PTS in the MC-CDMA systems. Simulation results prove that the proposed ABC-PTS scheme shows a significant improvement in PAPR reduction performance, with a low computational complexity. In addition, the bit-error-rate performance of the MC-CDMA with the ABC-PTS and the conventional PTS is compared when the HPA and the linear amplifier are used. - Author(s): H. Yu ; S. Ruepp ; M.S. Berger
- Source: IET Communications, Volume 5, Issue 8, p. 1163 –1171
- DOI: 10.1049/iet-com.2010.0378
- Type: Article
- + Show details - Hide details
-
p.
1163
–1171
(9)
This study focuses on the multicast scheduling for M×N input-queued switches. An enhanced first-in-first-out -based round-robin multicast scheduling algorithm is proposed with a function of searching deeper into queues to reduce the head-of-line (HOL) blocking problem and thereby the multicast latency. Fan-out information of each input cell composes a traffic matrix and the scheduler executes a round-robin algorithm on each column independently. Scheduling decisions result in a decision matrix for the scheduler to release multicast cells accordingly. A matrix operation called sync is carried out on the decision matrix to reduce the number of transmission for each cell. To reduce the HOL blocking problem, a complement matrix is constructed based on the traffic matrix and the decision matrix, and a process of searching deeper into the queues is carried out to find cells that can be sent to the idle outputs. Simulation results show that the proposed function of searching deeper into the queues can alleviate the HOL blocking and as a result reduce the multicast latency significantly. Under both balanced and unbalanced multicast traffic, the proposed algorithm is able to maintain a stable throughput.
Performance analysis of free-space optical links with transmit laser selection diversity over strong turbulence channels
Time series prediction with performance guarantee
Convergence of utility-based power control in Gaussian interference channel
Low-overhead uplink scheduling through load prediction for WiMAX real-time services
Time-delay alignment technique for a randomly distributed sensor array
Energy-efficient cooperative routing algorithm with truncated automatic repeat request over Nakagami-m fading channels
Radio resource allocation in OFDM-based cooperative relaying networks for a mixture of elastic and streaming traffic
Performance of an efficient heuristic scheduling algorithm for MPEG-4 traffic in high data rate wireless personal area network
Amplify-forward and decode-forward cooperation relying on systematic Luby transform coded Hybrid Automatic-Repeat-reQuest
Optimisation of satellite optical transmission with correlated sways
Microwave wireless orthogonal frequency division multiplexing system optimum guard interval evaluation in an urban scenario around 5 GHz
Highly selective and tunable microwave photonic filter using parallel Fabry–Pérot filters for universal mobile telecommunications system noise and interference suppression
Visualisation of efficiency coverage and energy consumption of sensors in wireless sensor networks using heat map
Novel path computation element-based traffic grooming strategy in Internet protocol over wavelength division multiplexing networks
Enhancing e-learning experience with online social networks
Partial transmit sequences based on artificial bee colony algorithm for peak-to-average power ratio reduction in multicarrier code division multiple access systems
Enhanced first-in-first-out-based round-robin multicast scheduling algorithm for input-queued switches
Most viewed content for this Journal
Article
content/journals/iet-com
Journal
5
Most cited content for this Journal
-
A review on security threats, vulnerabilities, and counter measures of 5G enabled Internet‐of‐Medical‐Things
- Author(s): Mohammad Kamrul Hasan ; Taher M. Ghazal ; Rashid A. Saeed ; Bishwajeet Pandey ; Hardik Gohel ; Ala’ A. Eshmawi ; S. Abdel‐Khalek ; Hula Mahmoud Alkhassawneh
- Type: Article
-
Compressive sensing-based coprime array direction-of-arrival estimation
- Author(s): Chengwei Zhou ; Yujie Gu ; Yimin D. Zhang ; Zhiguo Shi ; Tao Jin ; Xidong Wu
- Type: Article
-
Massive MIMO: survey and future research topics
- Author(s): Daniel C. Araújo ; Taras Maksymyuk ; André L.F. de Almeida ; Tarcisio Maciel ; João C.M. Mota ; Minho Jo
- Type: Article
-
Performance analysis of non-orthogonal multiple access in downlink cooperative network
- Author(s): Jinjin Men and Jianhua Ge
- Type: Article
-
Non-orthogonal multiple access schemes with partial relay selection
- Author(s): Sunyoung Lee ; Daniel Benevides da Costa ; Quoc-Tuan Vien ; Trung Q. Duong ; Rafael Timóteo de Sousa Jr.
- Type: Article
