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With a possible exhaustion of global IPv4 addresses, shifting to IPv6 is thought to be inevitable. However, when the shifting to IPv6 actually occurs, network topology could be inferred from addresses in the organization. Thus, as a means to conceal network topology, various methods, including the use of Mobile IPv6 and the setting-up of routers for host routes, are being proposed. However, redundant...
Cognitive radio (CR) is an exciting technology to improve spectrum utilization. However, spectrum availability can change very fast due to primary user's activity, which makes most of existing CR routing protocols fail to work because they are designed for cognitive radio networks (CRNs) with slow variation of spectrum availability. Opportunistic routing is a promising routing paradigm for CRNs with...
This paper proposes a new image authentication scheme, which is done in the wavelet domain. A magnitude of coefficient in selected sub-bands is determined in terms of bit plane data. An image feature is generated from this data and then signed to be a digital signature. The Signature can be embedded into host image or separately send. The feature is only 256 bytes. With the proposed scheme, image...
A novel robust least squares constant modulus algorithm (LSCMA) is proposed for blind adaptive beamforming, which is based on explicit modeling of uncertainty in the desired signal array. To improve robustness, the weight vector is optimized to involve minimization of cost function, while imposing the oblique projection constraint on the weight vector and maintaining a distortionless response for...
Multiple antenna solutions are likely to be adopted by the infrastructure-to-vehicle (I2V) communication systems to provide a cost effective coverage by the roadside access points (RAPs) along the motorways. In this paper, different antenna configurations at the RAP and at the vehicle are investigated in order to obtain the antenna design guidelines for the downlink of the I2V systems. At the RAP,...
The information and communication technolo-gies(ICT)industry has emerged as one of the main future consumers of the world energy and the radio access network, specially BS(base station) consumes over 80%. Thus this paper focuses on the BS energy efficiency issues of heterogeneous cellular networks. We analyze the energy saving potential of adaptively turning on and off some BSs to minimize the number...
Wireless sensor networks (WSN) is becoming large-scale. It's meaningful to gather sensor data quickly and efficiently. In this paper, we present a new approach to collect sensor data by distributed rateless coding. Rateless codes, such as Luby Transform (LT) codes have been proved possessing a very good property that receivers can decode all k original packets from arbitrary k(1+ε) encoded packets...
Orthogonal frequency division multiplexing (OFDM) system has the problem of high peak-to-average power ratio (PAPR) due to its multiple sub-carriers. In general, partial transmitted sequence (PTS) technique is applied to obtain optimal PAPR reduction performance, but its exhausted search for the optimal phase factors must be accomplished accordingly. As the number of sub-blocks and phase factors increase,...
In this paper a procedure for deconvolving signals in a Discrete Wavelet Transform (DWT) framework is applied to the estimation of impulse responses of fast-fading communications channels. Specifically, the effects of using several different wavelets on the performance of such wavelet-domain channel estimation is investigated. Monte Carlo simulations are performed using eight different wavelets. The...
An increasing demand for wireless access to packet-based services has, in turn, driven the need for call admission control strategies to make network roaming more seamless. This paper investigates the optimal call admission control (CAC) policy for heterogeneous wireless networks based on Markov Decision Process (MDP) and Value Iteration Algorithm (VIA). We concentrate on the optimization problems...
QoS routing protocol has become a hot research spot. However, it is difficult to offer guaranteed QoS, such as bandwidth, delay and delay jitter. To solve this problem, we proposed a Delay-Minimized Routing protocol based on Bandwidth Estimation (DMR-BE) that incorporates an admission control scheme and a route decision scheme to meet the QoS requirement of bandwidth and real-time applications. Bandwidth...
Multihop tactical network applications require that mission-critical data should be guaranteed to be delivered to their corresponding targets in time. However, end-to-end QoS (Quality of Service) assurance in multihop networks is a very challenging topic. Several schemes have been proposed to provide end-to-end delay assurance for multihop wireless network environment. However, these schemes do not...
In this paper, we investigate various greedy behavior scenarios that may appear in IEEE 802.11 wireless networks, and provide performances of the MAC layer using a two-dimensional Markov chain analytical model. We obtain the performance of greedy behaving nodes having different Poisson packet arriving rates for different wireless network topology structures and multiple greedy strategies. Besides...
Recommender systems have been widely used as an important response to information overload problem by providing users with more personalized information services. The most popular core technique of such systems is collaborative filtering, which utilizes users' known preference to generate predictions of the unknown preferences. A key challenge for collaborative filtering recommender systems is generating...
This paper studies network selection issues in cooperative cognitive radio networks (CRNs) where secondary users (SUs) have access to the combined spectrum pool of cooperating CRNs. Motivated by the service degradation of SUs caused by unnecessary network handover in cooperative CRNs, we formulate the network selection problem as a nonlinear optimization problem to minimize overall SU handover probability...
Spectrum sensing is one of the fundamental problems for cognitive radio. In cognitive radio networks, cognitive radios can cooperatively sense the spectrum to detect the presence of primary users with higher sensitivity. This paper proposes distributed consensus algorithms for decision fusion based cooperative spectrum sensing. Both theoretical analysis and simulations are performed to show the convergence...
This article puts forward a method for codebook design to support beamforming mechanism in a 60GHz millimeter-wave wireless communication environment. The codebook is designed with only phase shifting but not any amplitude adjustment to meet the low power consumption requirement. IEEE802.15.3c beam MRA (main response axis) directions are taken as the original version to make curve fitting, so that...
The IEEE 802.15.4 medium access control (MAC) protocol, which is widely used in current WSN deployments, does not provide any hidden node avoidance mechanisms. This leads to severe performance degradation in IEEE 802.15.4 MAC protocol in the presence of hidden nodes. In this paper, we apply a discrete-time Markov Chain model to analyse the throughput of IEEE 802.15.4 MAC protocol in the presence of...
We propose a noise-robust continuous speech recognition (CSR) method for recognition. In model building, we extract the novel feature vector by using running spectrum analysis (RSA) and dynamic range adjustment (DRA) methods. DRA adjusts the dynamic range on MFCC modulation spectrum domain (MSD). In recognition, the algorithm automatically divides the continuous speech into short sentences and blocks,...
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