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The following topics are dealt with: signal processing; cognitive radios and networks; communication systems; network protocols and performance; ad hoc sensor network; telecommunication security; and mobile computing systems and technologies.
For multi-source relay-based cooperative communications, it is widely believed that Complex Field Network Coding (CFNC) achieves better throughput performance than Physical-layer Network Coding (PNC). However, traditional CFNC schemes suffer a considerable loss on the performance of symbol to error ratio (SER) and peak-to-average power ratio (PAPR) as the number of source nodes increases. In this...
When the electromagnetic waves propagate over the sea surface, there exists reflection, scattering and diffraction. Impact of sea clutter to the communication link is an important issue to evaluate and demonstrate. In this paper, we simulate the communication transmitter and receiver and use the theory of random bridge to build a random multipath channel model of the sea surface. Combined with typical...
In this paper, we develop a novel codebook with low storage and complexity. The proposed codebook is constructed by cyclically shifting certain unit-norm vectors which satisfy the mutually unbiased condition. Moreover, an FFT-based algorithm, whose time complexity increases logarithmically with the number of transmit antennas, is proposed. Simulation results show that the proposed scheme is very suitable...
Concurrent multipath transfer (CMT) can improve data throughput, bandwidth resource utilization and system robustness. Whereas, CMT also leads to serious reordering problem, especially in heterogeneous wireless networks. Since more than one path are used, an efficient CMT scheduling algorithm is needed at the sender. For existing packet scheduling, packet's rate of entering the sender queue is usually...
A reconfigurable ultra-wideband (UWB) bandpass filter (BPF) with tunable notch band for UWB system is presented in this paper. The UWB BPF adopts the proposed stub-loaded multiple-mode resonator (MMR) structure and RF-MEMS switched capacitor network which is used for electronic tuning. The filter is printed on a Roger's RT/Duriod 6010 substrate with the dimensions of 10 mm × 10 mm × 1.2 mm and relative...
OvTDM is a new transmission scheme that can obtain high spectral efficiency with very low threshold signal noise ratio (SNR) by using the inter symbol interference (ISI). Fano algorithm (FA) is researched in this paper to implement fast ML decoding at high spectral efficiency for OvTDM. Numerical results show that the complexity of OvTDM with FA has no relationship with the number of state which is...
Network selection is a key problem when a user faces multiple available wireless networks. Especially, this problem becomes more complicated when multiple users share multiple wireless networks due to the interaction and competition among users. Most existing works on this multiple networks sharing problem assume that users have the same utility functions, which neglect the fact that users may have...
Cloud system peculiarities, such as dynamic virtualization management and multi-tenant shared mode, make authentication and access control more important than ever. This paper presents an advanced Access control model based on the TCG'IF-MAP standard and the OASIS XACML standard to regulate the access of Cloud resources. The main novelty of the architecture is the introduction of MAP server, providing...
Tag collision occurs when a reader attempts to identify a large number of tags simultaneously, which reduces the identification efficiency of RFID systems. The dynamic slots collision tracking tree algorithm (DSCTTA) can reduce the prefix overhead and iteration overhead by using time-divided responding scheme, however, this mechanism generates a lot of idle time slot. An improved dynamic slots collision...
The algorithm is developed for choosing the most appropriate route with the help of dynamic routing table. The research direction of network-on-chips (NoC) is essential. The aim is to control the congestion which would cause very serious consequences.After NoC's wide application in variety of systems, how to improve the speed of communication among chips, which means how to control congestions effectively,...
Vehicular ad hoc networks (VANETs) are a special type of mobile ad hoc networks (MANETs), where nodes are moving vehicles that communicate with one another wirelessly. The promising technology of VANETs will enable variety of applications from safety to driver assistance. Routing protocols that work efficiently in MANETs perform poorly in VANETs due to high-speed mobility of nodes, resulting in frequent...
To cope with challenging communication conditions in VANETs where connectivity is intermittent, and the quality of wireless channel is unstable and communication links are easily broken, we present an improved infrastructure assistant vehicle-to-passenger (V2P) protocol was proposed. The proposed protocol can reach very high query efficiency and matching accuracy with low delivery delay and communication...
In this paper, we analyze the effect of cooperation for spectrum sensing based on relay with equal gain combining in cognitive radio networks. The performance of energy detection in cognitive radio network over a number of cognitive radio users is evaluated. The probability of detection and probability of false alarm are calculated and simulated. We found that when the square of the sum of the gains...
In cognitive radio networks, the process of sensing the potential channels and choosing free ones to access in is called spectrum access. In this paper, three spectrum access schemes are compared. They are sensing-all before accessing scheme, Partially Observable Markov Decision Process (POMDP) based scheme and sequential channel sensing scheme. The efficacy of these schemes is studied by both theoretical...
In this paper, through jointly considering the interference caused to the primary user (PU) from one pair of secondary transceivers, the optimal power allocation is studied for the underlay cognitive two way network. Under the quality of service constraint of the PU transmission, two different objective functions are considered for the SUs to maximize the sum achievable rate or maximize the minimal...
In order to achieve better spectral efficiency, several prototypes have been suggested as physical layer candidates for cognitive radio systems as OFDM (Orthogonal Frequency Division Multiplexing), SRRC (Square Root Raised Cosine) and others. In such models, we are confronted to problems of interference between the cognitive users and licensed users which degrade the performances of using models....
In this paper, we propose a robust pre-coder design method for Cognitive Radio Multi-Input Multi-Output (CR-MIMO) system under the consumption that the channel state information (CSI) estimations are imperfect from secondary base station (SBS) to primary user (PU) and secondary user (SU). Due to the uncertainties of the channel estimation error, both the outage probability of the received SNR of SU...
Because of different characteristics, the performance of traditional mobile ad hoc networks (MANETs) routing protocols is demonstrated poor in vehicular ad hoc networks (VANETs). Therefore, many routing protocols have been designed for VANETs during past few years. Most of these protocols utilized vehicular traffic to find optimal routing paths in urban environments. Although choosing the road segments...
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