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781.
This paper studies clutter’s effect on MIMO radar performance through obtaining closed-form Cramer Rao lower bounds (CRLBs) for the range and velocity parameters versus the powers assigned to the transmit antennas which resulted in more calculation’ complexity. To verify extracted CRLBs, the maximum likelihood estimation’s error variance (MLEEV) of range and velocity were derived in attendance of clutter. Based on obtained closed-form CRLBs, four optimized power allocation (PA) strategies are proposed which consider measurement error statistics as the objective function or constraints to improve radar performance. So, the calculated closed-form CRLBs are simplified to the closed-forms versus assigned powers to the transmitters. Simulation results verify the proposed CRLBs’ accuracy, and improvements have been made by proposed power allocations. 相似文献
782.
The objective of this paper is to propose techniques for enhancing the physical layer security (PLS) performance of half-duplex cooperative non-orthogonal multiple access (HD-CNOMA) network in the presence of an external passive eavesdropper. We propose an artificial noise (AN)-aided framework and derive approximate analytical expressions for the secrecy outage probabilities (SOPs) of the downlink users. It is demonstrated that the proposed AN-aided framework significantly reduces the SOPs of the users and completely resolves the zero-diversity order problem, which is prevalent in HD-CNOMA network without AN. To further enhance the PLS performance, we determine optimal power allocation coefficients (OPACs) for the downlink users at the base station (BS) that minimizes the system SOP (SSOP) of the AN-aided HD-CNOMA network. With the help of extensive numerical and simulation investigations, it is shown that the proposed OPAC leads to significant reduction of the SSOP, while lowering the SOPs of the users, compared to random/equal setting of the PACs. 相似文献
783.
Artificial bee colony (ABC) algorithm builds on simulating the intelligent behavior of honey bees. It shows good performance in many applications. As standard ABC algorithm does not employ any crossover operator, the dispersal of good genetic information amongst the solutions is undermined. In this paper, the impact of crossover operators on the performance of ABC is studied. Eight crossover operators, representing all kinds of crossover operators, are used in this study. A trial and error method is used to detect the most proper crossover operator and crossover rate for incorporation into the ABC algorithm on mathematical functions as an initial attempt. The overall best configuration of ABC with crossover which has been identified is then applied to solve power allocation problem in cognitive multiple input and multiple output orthogonal frequency division multiplexing (MIMO-OFDM) cognitive system. Promising performances are obtained when compared with those from genetic algorithm, particle swarm optimization and differential evolution algorithm. 相似文献
784.
Recently, with the rapid growth of demands for wireless communications, dynamic spectrum allocation is one of the key technologies in cognitive radio networks to resolve the realistic problem of low utilization efficiency of spectrum. It mainly focuses on how the spectrum owner dynamically allocates idle spectrum to secondary users who have no licensed spectrum for communications. In this paper, a dynamic spectrum allocation model based on auction theory in a two-tier heterogeneous network is proposed, in which the primary users (PUs) are the sellers, the central processor (CP) auctioneer is the coordinator, and femtocell base station (FBS) as the buyer bids for the idle spectrum and act as a wireless access point that provides communication services for secondary users (SUs). Its basic process is as follows: the auctioneer gradually raises the spectrum price from the reserved price; each bidder decides whether participates in the purchase or not. It is characterized by distributed execution and low complexity which can reduce unnecessary information exchange between primary users or secondary users. Meanwhile it can enhance the utilization of spectrum and improve the efficiency of the auction by generate the incentive mechanism. 相似文献
785.
Exponential dispersion models are well used and studied in quantitative risk management and actuarial science. One of the main interests is the risk measurement analysis of such models when facing extreme loss events. In this paper, we propose two multivariate risk measures based on conditional expectation and derive the explicit formulae for exponential dispersion models. In particular, our multivariate risk measures could facilitate a systemic risk measure with explicit expressions for exponential dispersion models subject to any pre-specified “systemic event.” We provide two numerical examples based on practical data to show the advantages of our approach in the context of exponential dispersion models. 相似文献
786.
787.
在最短路修复合作博弈中,当灾后运输网络规模较大时,最优成本分摊问题难以直接求解。基于拉格朗日松弛理论,提出了一种最短路修复合作博弈成本分摊算法。该算法将最短路修复合作博弈分解为两个具有特殊结构的子博弈,进而利用两个子博弈的结构特性,可以{高效地}求解出二者的最优成本分摊,将这两个成本分摊相加,可以获得原博弈的一个近乎最优的稳定成本分摊。结果部分既包含运输网络的随机仿真,也包含玉树地震灾区的现实模拟,无论数据来源于仿真还是现实,该算法都能在短时间内为最短路修复合作博弈提供稳定的成本分摊方案。 相似文献
788.
群体单调分配方案(Population Monotonic Allocation Scheme, 后简称PMAS)是合作博弈的一类分配机制。在合作博弈中, PMAS为每一个子博弈提供一个满足群体单调性的核中的分配方案, 从而保证大联盟的动态稳定性。本文主要贡献为利用线性规划与对偶理论构造与求解一类基于最短路问题的合作博弈(最短路博弈)的PMAS。我们首先借助对偶理论, 利用组合方法为最短路博弈构造了一个基于平均分摊思想的PMAS。然后借鉴计算核仁的Maschler方案, 将PMAS的存在性问题转化为一个指数规模的线性规划的求解问题, 并通过巧妙的求解得到了与之前组合方法相同的最短路博弈的PMAS。 相似文献
789.
Poulami Dalapati Piyush Agarwal Animesh Dutta Swapan Bhattacharya 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2018,24(5):485-505
This paper addresses the issues concerning resource allocation and process scheduling in a dynamic environment, where resources are distributed and availability of them is uncertain. In this context, we introduce a new multi-agent-based resource allocation and process scheduling approach, where agents communicate and cooperate among themselves to produce an optimal schedule. A distributed constraint optimization problem-based model in accordance with Markov Decision Process is proposed in this regard. We overcome the hardship of existing centralized approach and our technique optimizes not only the process completion delay but also the number of resources being idle, which is much more beneficial. Apart from the theoretical approach, we take a case study in its practical application domain to validate our claim. Analysis and experimental results show that this proposed method outperforms the state-of-the-art methods and bridges the gap between theory and its applications. 相似文献
790.