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In this paper, a novel adaptive maximum ratio combining (MRC) rake receiver using genetic algorithm (GA) is proposed. The proposed adaptive GA Rake receiver uses GA to adaptively select the delays of Rake receiver fingers depending on the channel impulse response. It adaptively selects the delays that will allow the Rake receiver to capture most of the energy of the multipath components with less...
Spectrum sensing is being widely researched as the key tool used by the cognitive radios to gain awareness of their surrounding radio environment. Non-parametric spectrum sensing techniques such as energy detection and cyclostationary feature detection are preferred over the parametric techniques because any practical visualisation of cognitive radios would necessitate minimum assistance by the primary...
In this paper, we analyze the applicability of Constant Modulus Algorithm (CMA), one of the most widely used and tested blind equalization technique to blind image deconvolution. With a detailed mathematical analysis, we show that the strong correlation between the neighboring spatial locations found in natural images becomes a major constraint on the convergence of CMA. In order to overcome this...
One of the key challenges for routing protocols in wireless multi-hop networks is to deal with link failures, and to repair the routes in these situations. In the Ad-hoc On Demand Distance Vector (AODV) protocol, routes can either be repaired by re-establishing a new route from scratch starting from the source node (Source Repair), or they can be locally repaired by the node that detects the link...
Due to the mobility of nodes, servers and clients, the reliability of service delivery over MANETs is a major concern. Traditional route discovery based method is to predict and detect breakdown of connectivity and try to find an alternative path from the client to the same server (We call it traditional rerouting method). The introduction of service delivery platform over MANETs enables and facilitates...
In this paper we present main parameters of the ringing artefact and demonstrate their influence on image fidelity of lossy compressed images. We apply variations of these parameters to create a specific set of test images to highlight the ringing artefact and to be able to evaluate the behaviour of ringing along edges. Therefore we introduce a new ringing metric, that analyzes image profiles of compressed...
In decentralized Cognitive Radio (CR) networks timing errors between secondary users cause increased interference during sensing periods. This kind of intra-network interference inflicts significant performance degradation due to the growth of false alarm probabilities if energy-based incumbent detection is used, as shown in our previous study. Therefore, in this paper we propose a novel interference...
In this paper, a novel bipolar time-spread (TS) echo hiding based watermarking method is proposed for stereo audio signals, to overcome the low robustness problem in the traditional TS echo hiding method. At the embedding, echo signals with opposite polarities are added to both channels of the host audio signal. This improves the imperceptibility of the watermarking scheme, since added watermarks...
In time domain synchronous (TDS)-OFDM, the channel estimation is conventionally carried out based on the pseudo noise (PN) sequence. The PN sequence based channel estimation however suffers interference from adjacent OFDM data symbols. This paper proposes a new low-complexity data-aided channel estimation method with two-dimensional (2-D) estimate refinement and interpolation. Data-aided channel estimation...
In this paper we investigate the reduction in sensing time that can be gained by using a coarse-fine sensing scheme. Since the speed gains that can be obtained are dependent upon the SNR distribution across the bands, we generate an example SNR distribution based on the Irish DTV network for use in this paper. The coarse-fine sensing scheme in this system uses an energy detector first to order the...
The visual quality obtained in wireless transmission strongly depends on the characteristics of the wireless channel and on the error resilience of the source coding. The wireless extensions of the JPEG 2000 standard (JPWL) and H.264 are the latest international standards for still image and video compression, respectively. However, few results have been reported to compare the rate-distortion (R-D)...
Improvements in network infrastructures, storage capacity and computing power, along with advances in video coding technology, are enabling an increasing popularity of multimedia applications. Traffic modeling plays an important role in the performance evaluation of network architectures and protocols. In this paper, we describe a tool for video traffic modeling. A graphical user interface is presented...
The rapidly increasing contribution towards global warming from the information communication technology (ICT) sector is a clear indication of the need for energy efficient green communication networks. For instance, in the case of cellular networks, over 80% of the total energy is consumed at the access network. On the other hand, incorporating self-sustainability and autonomy in its operation, control,...
The method by which individual decisions are combined in cooperative cognitive radio networks is crucial to minimising the overall probabilities of false alarm and missed detection. In this paper, general expressions for these probabilities are derived for a double threshold energy detector-based network, and an analytical solution for the optimal value of voting rule is found so that the overall...
This paper presents a new interference avoidance method based on Genetic Algorithm (GA) to obtain an optimal set of transmission parameters for cognitive radio-based multicarrier systems operating in the same band as digital television (DTV). To this end, both interference analysis techniques and interference temperature model are employed to find out the maximum allowable transmit power for each...
This paper introduces a novel Trellis Coded Multiple Access (TCMA) technique which takes advantage of Trellis-Coded Modulation (TCM) and signalling set redundancy to differentiate transmissions from different users. The proposed TCMA scheme exploits modulation with memory principles to provide the flexibility of accommodating an increasing number of users within the fixed time-frequency resource....
Mobile swarms of autonomous underwater vehicles (AUV) have exciting potential for extending current AUV applications and adding new possibilities to the working environment of the oceans. For swarm operations to occur, fast reliable communication between all vehicles within the swarm is needed. The challenge for underwater communication is the very different and unique characteristics of the channel...
In this paper, we propose a new score function for subband decomposition ICA to improve the algorithm performance. Subband decomposition ICA is known to having better separation performance than frequency-domain ICA. However, it is basically time-domain ICA, with much shorter filters, performed on each subband. In this paper, discussion is focused on an information-maximization based approach which...
Error control techniques in wireless links such as Automatic Repeat Request (ARQ) and Forward Error Correction (FEC) are still quite effective approaches in the improving system throughput in particular in time-varying channel environments. In this paper, a dual-branch selection diversity receiver of combining Selective Repeat-ARQ scheme and BCH channel coding (hybrid ARQ) in mobile cellular networks...
In recent years, as the deployment of Wireless Local Area Networks (WLAN) in dense-urban areas is growing rapidly, it can be a perfect supplement for providing location information of users in indoor environments where other positioning techniques such as GPS, are not much effective. However, most systems only focus on the network deployment for positioning but overlook that the original purpose of...
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