By Topic

Networks, IET

Issue 2 • Date June 2012

Filter Results

Displaying Results 1 - 6 of 6
  • Optimal and sub-optimal resource allocation in multi-hop cognitive radio networks with primary user outage constraint

    Page(s): 47 - 57
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (387 KB)  

    In this study, the authors propose a cross-layer optimisation framework for cognitive radio networks (CRNs) by jointly taking into account the physical layer and transport layer. In particular, they focus on joint rate and power control for a multi-hop CRN to maximise the network utility without affecting the performance of primary users (PUs). The formulation is shown to be a non-linear non-convex optimisation problem. To solve the problem, the authors first use a successive convex approximation method, which has been proved to converge to the global optimum. Then, the authors propose a novel heuristic method to develop a practical sub-optimal distributed algorithm without explicit message passing. The authors have proved that the proposed distributed algorithm is able to converge to the unique fixed point near the global optimum. Finally, the illustrative results indicate that the proposed sub-optimal algorithm outperforms the high-signal-to-interference-ratio-based algorithm and closely approaches the global optimum. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance analysis and optimisation of a cooperative frequency-modulated differential chaos shift keying ultra-wideband system under indoor environments

    Page(s): 58 - 65
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    A cooperative frequency-modulated differential chaos shift keying (FM-DCSK) ultra-wideband (UWB) systems, named cooperative FM-DCSK UWB system, is investigated under indoor environments of IEEE 802.15.4a in this article. The performance of the cooperative FM-DCSK UWB system is evaluated in such channel models (CMs), that is, CM1-CM4, by means of the moment generating function. Monte Carlo simulation results show that the bit-error-rate performance of the proposed system is much better than the conventional multi-access FM-DCSK UWB system, which is showed to be highly consistent with the theoretical results. The integration interval of the proposed cooperative UWB system is optimised to further improve the system performance through the binary search algorithm. Meanwhile, aiming to provide a good compromise between the system performance and implementation complexity, the number of received antenna at the destination (single-input multiple-output architecture) is also investigated and discussed. For the aforementioned advantages, the proposed system can be seen as a viable alternative to other multi-access FM-DCSK UWB schemes for the low-rate and low-power wireless personal area network and wireless sensor network applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Energy efficient network-flow-based algorithm for multiuser multicarrier systems

    Page(s): 66 - 73
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (377 KB)  

    The resource allocation problem of minimising transmission power with per user rate constraint is studied for energy efficiency of multiuser multicarrier systems. The authors introduce an algorithm that deploys a flow-based decomposition strategy, called the network-flow-based algorithm (NFBA), to circumvent the NP-hard complexity of the resource allocation problem. The authors prove global optimality of the algorithm for the case of a flat-fading channel. For the general frequency selective channel, the flow size is adjusted adaptively to minimise the transmission power. Also, a compact integer programming formulation is developed to provide tight lower and upper bounds of the minimum power. Numerical results show that the authors' proposed NFBA achieves near-optimal performance with polynomial complexity even for large-scale systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Balanced feature selection method for Internet traffic classification

    Page(s): 74 - 83
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (719 KB)  

    In Internet traffic classification, the class imbalance problem is mainly addressed by adjusting the class distribution. In the meanwhile, feature selection is also a key factor evoking this problem. Therefore a new filter feature selection method called balanced feature selection (BFS) is proposed. Every feature is measured both locally and globally and then an optimal feature subset is selected by our search model. A certainty coefficient is presented to measure the correlation between a feature and a certain class locally. The symmetric uncertainty is utilised to measure a feature and all classes globally. Through experiments on two real traffic traces using three classification algorithms, BFS is compared with five existing feature selection methods. Results show that it outperforms others by more than 15.29% g-mean improvement. Classification results are averaged over all datasets and classifiers here, 59.54% g-mean, 86.35% Mauc and 91.42% overall accuracy are achieved, respectively, when it is used. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed interference-aware relay selection for IEEE 802.11 based cooperative networks

    Page(s): 84 - 90
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    Cooperative communication has been recently proposed as a way to mitigate fading in wireless networks. Analytical results indicate that network performance improvement by cooperative communication heavily depends on selecting suitable relay nodes. Previous work on relay selection fails to consider the impact of inter-node interference among transmissions, which potentially results in a degradation of network performance. In this study, it is shown how the use of relay nodes may degrade rather than improve network performance (e.g. throughput) in scenarios where inter-node interference is not accounted for. In this approach, inter-node interference is embedded into our relay selection strategy through a newly proposed distributed interference-aware relay selection (DIRS) algorithm for IEEE 802.11-based wireless networks with multiple source-destination pairs. Under DIRS algorithm, each source-destination pair will select an optimal relay based on both the channel quality and the interference information, which can be obtained locally without the knowledge of topology information. The simulation results demonstrate the effectiveness of our proposal and show that inter-node interference can be mitigated by optimising relay selection. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modelling and analysing medium access delay for differentiated services in IEEE 802.11s wireless mesh networks

    Page(s): 91 - 99
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    Wireless mesh networks (WMNs) has been actively explored for a few years, and the IEEE 802.11 Task Group “s“ has recently approved the active 802.11s standard for Wireless local area network (WLAN) mesh networking. To provide differentiated channel access and quality of service (QoS) guarantees for multimedia flows, IEEE 802.11s standard employs enhanced distributed channel access (EDCA) as the basic medium access control (MAC) protocol. In this study, the authors focus on modelling and analysing the medium access delay differentiation of EDCA under saturation condition in multi-hop WMNs. The authors develop a three-dimensional Markov chain model to evaluate the medium access delay differentiation of EDCA. In this model, the authors fully consider the performance impact of Request to Send (RTS) frame collisions and data frame collisions and then put forward the pseudo states to distinguish the different back-off procedures induced by these collisions. Using this analytical model, the authors derive the average medium access delay for the flows with different priorities. Comparisons with the simulation results show that the analytical model is extremely accurate. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IET Networks covers the fundamental developments and advancing methodologies to achieve higher performance, optimized and dependable future networks.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Han-Chieh Chao
National Ilan University