Current Issue : April - June Volume : 2015 Issue Number : 2 Articles : 6 Articles
A disturbed load sharing leads to performance degradation of the network. Due to this unbalancing nature, few nodes in the network are exceedingly overloaded with routing duties which causes the large queue size, high packet delay, high packet loss ratio and high power consumption. The performance investigation and simulation are carried out to evaluate network performance using network simulator NS-2 based on the quantitative basic parameters for node management techniques like throughput, delay and packet delivery ratio in term of number of nodes and different mobility rates. The performance analysis and simulation are carried out to evaluate network performance using network simulator. Network simulator tool based on the quantitative basic parameters like throughput, end to end delay in term of number of nodes and a variety of mobility rates. A research results was during the evaluation of existing protocol with proposed protocol the probability of route stability, link break and delay has been possibly decreases in proposed system....
Vehicle sensing system is an important research topic in the research field of Internet-of-Vehicles (IoV). Reliability and\nreal-time performance of vehicle sensing systems are greatly influenced when deadlock happens. When a deadlock is\ndetected, identifying the optimal deadlock solving strategy can ensure that the system goes back to normal state\nquickly. In order to address this issue, this paper proposes an efficient deadlock solving method. Firstly, the deadlock\nproblem in a vehicle sensing system is analyzed based on four deadlock occurring conditions (i.e., mutual exclusion,\nhold and wait, no preemption, and circular wait). Secondly, an optimization model is built to combine the quantity\nand cost of tasks in vehicle sensing systems. After that, a co-evolutionary genetic algorithm (CGA) is developed to\nsearch the optimal deadlock solving strategy. Finally, experiments by simulation are conducted and the experimental\nresults show the efficiency of the proposed deadlock solving method for vehicle sensing systems....
With the introduction of small cell into current macro cell structure, the ever-growing demand for mobile data\nservice has the opportunity to be fulfilled. But the correspondingly overlaid dense deployment situation caused by\nthe Heterogeneous Network (HetNet) also arouses the interference and mobility management problems. In order to\nsolve the above problems, we propose the Joint Voronoi diagram and game theory-based power control scheme\nfor the HetNet small cell networks with two-step approach. The first step focuses on the optimization of the small\ncell cluster deployment planning within the coverage of the macro cell. The intra-tier interferences are mitigated by\nthe min-max power allocation algorithm and the mobility management performance can also be improved by the\nVoronoi diagram-based scheme. Then, the second step addresses on the mitigation of cross-tier interferences while\nprotecting the guaranteed users and high-mobility users usually served by the macro cells. The game theory-based\ndynamic power control scheme is proposed via non-cooperative game model with the convex pricing function.\nThe existence and uniqueness of the Nash equilibrium for the proposed game model are verified, which provide\nthe feasible solution for the cross-tier power control in the heterogeneous network. From the observation of the\nsystem-level simulation results, the proposed scheme can bring a significant increase in the system throughput,\nreduce the outage probability, as well as enhance the energy efficiency over current works....
The use of multiple-input multiple-output (MIMO) communication systems has attracted considerable attention due\nto capacity and performance improvements without increasing the required bandwidth or transmission power.\nAlthough MIMO improves the transmission rate and provides reliable communication, these advantages come at a\nhigh cost, since multiple radio frequency (RF) chains have to be employed. Therefore, cost-effective implementation\nof MIMO systems remains as an important challenge. In this sense, antenna selection techniques (AST) can help\nreduce the high cost of MIMO systems, while retaining most of their benefits; and in order to improve channel\ncapacity, transmission power can be allocated efficiently according to the channel experienced by each antenna\nelement. In this paper, we show the channel capacity improvement of MIMO systems, by combining the use of AST\nand transmission power allocation through the water-pouring algorithm (WPA) for different antenna configurations.\nWe apply WPA and allocate more power to the channel with better conditions, when the MIMO channel is Rayleigh\ndistributed and noise is Gaussian. By employing these two techniques (AST and WPA), we show that channel capacity\nis significantly improved, with higher capacity values than those obtained using traditional systems which just spread\nequal power among all the transmit antennas. We also show that bounds on the capacity can be considered when\nthese improvements are used in a MIMO system....
With the rapidly increasing demand for high-speed data transmission and a growing number of terminals, massive\nmultiple-input multiple-output (MIMO) has been shown promising to meet the challenges owing to its high\nspectrum efficiency. Although massive MIMO can efficiently improve the system performance, usage of orthogonal\npilots and growing terminals causes large resource consumption especially when the coherence interval is short. This\npaper proposes a semi-orthogonal pilot design with simultaneous data and pilot transmission. In the proposed\ntechnique, we exploit the asymptotic channel orthogonality in massive MIMO systems, with which a successive\ninterference cancellation (SIC)-based channel estimation is applied to mitigate the mutual interference between data\nand pilot. We derived the theoretical expressions of the achievable rates in massive MIMO systems with our proposed\npilot design. Further discussion on performance verifies the superiority of our proposed pilot design for high or low\nsignal-to-noise-ratios (SNRs) with any coherence interval length. And simulation results show that the proposed pilot\ndesign can achieve a significant performance improvement with reduced pilot resource consumption compared with\nthe conventional orthogonal pilots....
The tremendous ongoing growth of wireless communications has increased spectrum shortfall and safety issues. A recent study on radio spectrum access suggests most of the licensed bands suffer from underutilization and less spectral occupancy of the spectrum. Cognitive radio (CR) technology is a new way to compensate the spectrum shortage problem of wireless environment. Spectrum sensing is a technique and important module in cognitive radio which sensed surrounding radio environment to determine the present or absence of the primary user (PU) in the licensed band. The main objective of this paper is a comprehensive study about the transmitter detection based spectrum sensing and the comparison among them. Finally, challenges associated with the spectrum sensing for CR are discussed in this paper....
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