IJCNIS Vol. 3, No. 5, Aug. 2011
Cover page and Table of Contents: PDF (size: 183KB)
This paper examines the information theoretic metric of outage probability for a decode-and-forward (DF) based asymmetric two-way relay transmission (i.e. the two source terminals have different target rates). We first characterize the achievable rate region of a conventional three-node network. After that the conventional three-node scenario is analyzed in terms of outage probability and the corresponding closed-from expressions are developed over Rayleigh fading channels. Moreover, in order to make a good use of the available diversity degrees of the channel, opportunistic relay selection are considered for multi-relay networks. Two significant relay selection strategies, i.e., the max-min and max-sum policies are studied and analyzed in terms of outage probability and diversity gain from the viewpoint of asymmetric traffics. Furthermore, a single-criterion based relay selection policy is proposed, which only uses the harmonic mean of the two-hop squared link strengths, thus in contrast to the hybrid scheme no additional overhead is required during the relay selection process. Numerical experiments are done and outage performance comparisons are conducted. Our results show that the proposed policy is an efficient and appropriate method to implement relay selection and can achieve significant performance gains in terms of outage probability regardless of the symmetry and asymmetry of the traffics and channels. Moreover, the simulation results also validate the accuracy of our derived expressions.[...] Read more.
With increasing social awareness on the issue of corporate social responsibility (CSR), the measurement of CSR has received considerable attention in both academic literature and managerial practice. Following a review of CSR theory development and the literature on measures of CSR, this paper proposes a systematic approach to measure CSR using fuzzy analytical hierarchy process (FAHP). In addition, a preliminary investigation is presented to explain how the approach can help in evaluating CSR in practice.[...] Read more.
In order to meet the high data rate, large capacity and low latency in LTE, advanced MIMO technology has been introduced in LTE system, which becomes one of the core technologies in physical layer. In a variety of MIMO detection algorithms, the ZF and MMSE linear detection algorithms are the most simple, but the performance is poor. MLD algorithm can achieve optimal detection performance, but it’s too complexity to be applied in practice. CLSD algorithm has similar detection performance and lower complexity with the MLD algorithm, but the uncertainty of complexity will bring hardware difficulties. FCLSD algorithm can maximize the advantages of CLSD algorithm and solve difficult problems in practice. Based on advanced FCLSD algorithm and combined with LTE / LTE-A practical system applications, this article designed two improved algorithms. The two improved algorithms can be flexibly and adaptively used in various antenna configurations and modulation scene in LTE / LTE-A spatial multiplexing MIMO system. The Simulation results show that the improved algorithm can achieve an approximate performance to the original FCLSD algorithm; in addition, it has a fixed complexity and could be carried out by parallel processing.[...] Read more.
The particle swarm optimization (PSO) algorithm is applied to the problem of blind parameter estimation of frequency hopping signals. For this target, one Time Frequency representation such as Smoothed Pseudo Wigner-Ville Distribution (SPWVD) is computed firstly. Then, the peaks on TF plane are searched using multi-species PSO. Each particle moves around two dimension time and frequency plane and will converge to different species, which seeds represent the centers of frequency hopping components. A numerical study is carried out for signals which are embedded in a very low SNR ratio noise. Results show that the new method is feasible and much more robust than some existing estimation algorithms.[...] Read more.
Over the past decade, researchers have been putting a lot of energy on co-channel interference suppression in the forthcoming fourth generation (4G) wireless networks. Existing approaches to interference suppression are mainly based on signal processing, cooperative communication or coordination techniques. Though good performance has been attained already, a more complex receiver is needed, and there is still room for improvement through other ways.
Considering spatial frequency reuse, which provides an easier way to cope with the co-channel interference, this paper proposed a bilayer beams and relay sharing based (BBRS) OFDMA cellular architecture and corresponding frequency planning scheme. The main features of the novel architecture are as follows. Firstly, the base station (BS) uses two beams, one composed of six wide beams providing coverage to mobile stations (MSs) that access to the BS, and the other composed of six narrow beams communicating with fixed relay stations (FRSs). Secondly, in the corresponding frequency planning scheme, soft frequency reuse is considered on all FRSs further. System-level simulation results demonstrate that better coverage performance is obtained and the mean data rate of MSs near the cell edge is improved significantly. The BBRS cellular architecture provides a practical method to interference suppression in 4G networks since a better tradeoff between performance and complexity is achieved.
We Study the performance of priority–based virtual channels scheduling algorithm in packet telemetry system. Probability of occupying physical channel by the virtual channel with the highest priority is considered, on condition that the packet arrival rate contribution is Poisson distribution. Packets losing rate of the virtual channel with the highest priority is also investigated, of which calculating formulas are given. An interesting conclusion is made by theoretical analysis and simulation experiments that when the running time of the scheduling module is long enough, both the probability of being scheduled and packets losing rate of the virtual channel with the highest priority converge on fixed values, which can offer reference to engineering design.[...] Read more.
The directed routing protocol ends in failure when it faces a situation of the destination node with a very low velocity in a sparse ad hoc network so that none of nodes exist in its forwarding zone. Illuminated by BFDREAM and ZONER, the paper firstly proposes a novelty routing protocol that is fairly immune to forwarding failure through projecting the present source node on the boundaries of baffle holes of underwater acoustic networks in deep sea. Compared with DREAM and BFDREAM, the experimental results show our protocol achieves a great improvement in decreasing the propagation delay and reducing quantities of the non-effect information. So the new protocol may have a bright application prospect in deep sea acoustic networks.[...] Read more.
Wireless Sensor Network usually is deployed open environment to collect some sensitive information and has special features of its own are different from traditional network, which is vulnerable to internal and external attacks. Whole network can be split up into many separate subnets which cannot communicate with each other because some vital sensor nodes are attacked. This paper proposed an effective countermeasure based on ARMA prediction model and frequency hopping to react against split-network attack. ARMA model is used to evaluate the behavior of sensor nodes. Frequency hopping makes the communication frequency of the network escape from attack frequency. Then wireless sensor network is integrated into single network from split-network. Simulation results show the proposed countermeasure significantly reduces the success rate of split-network attack and increases the lifetime of network.[...] Read more.