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为优化蜂窝用户通信与设备直传(D2D)中继通信共存下的同频干扰问题,满足蜂窝用户容量要求,提出了一种基于能效的联合资源分配和功率控制的D2 D中继选择算法.该算法首先对等效D2 D中继链路进行资源分配,减小算法复杂度的同时使得D2 D链路对蜂窝链路产生的干扰最小;然后以资源分配结果和功率控制算法为依据进行中继选择.该方案不仅考虑了D2 D中继链路的能效问题,而且还同时考虑到了对蜂窝链路的干扰问题.通过仿真验证,所提算法不仅能有效提升D2 D中继链路的能效值,同时降低了对蜂窝用户的干扰. 相似文献
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In order to save energy and make more efficient use of wireless channel, this article puts forward an energy saving cooperative relaying scheme which actuates the cooperative transmission only when the feedback from the destination indicates failure of the direct transmission. The proposed scheme selects the optimal relay and its corresponding transmission power in each time slot based on channel condition and residual energy with the objective of minimizing energy consumption and extending network lifetime. In the study, the finitestate Markov channel model is used to characterize the correlation structure of channel fading in wireless networks, and the procedure of relay selection and transmission power decision is formulated as a Markov decision process. Numerical and simulation results show that the proposed scheme consumes less energy and prolongs the network lifetime. 相似文献
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终端直通通信技术(Device-to-Device communication,D2D)是指相距较近的用户设备(user equipment,UE)可不借助于基站而直接进行通信,它可以有效提高传输速率和频谱利用率.受限于电池的容量,基站调度上应尽可能使终端的续航时间更长.为此,本文旨在追求单位能量的传输比特率最大化,即能效最大化目标.本文在构建蜂窝用户与D2D用户资源复用场景下的能效模型基础上,将目标实现分为两个步骤:1)终端最优发射功率的设置,利用准凸函数的性质,通过最优化的方法迭代求解蜂窝和D2D用户各自的最优功率,使得复杂度大为降低;2)利用KM算法实施蜂窝用户与D2D对的配对.通过仿真验证,使用本文提出的算法相对于以最大功率发送的情况下可以获得约40％左右的增益. 相似文献
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In this paper, we propose a low‐complexity resource allocation algorithm for the orthogonal frequency division multiplexing cooperative cognitive radio networks, where multiple primary users (PUs) and multiple secondary users (SUs) coexist. Firstly, we introduce a new concept of ‘efficiency capacity’ to represent the channel conditions of SUs by considering both of the interference caused by the PUs and the channel gains of the SUs with the assist of the relays. Secondly, we allocate the relay, subcarrier and transmission power jointly under the constraint of limiting interference caused to the PUs. Simulation results show that the proposed algorithm can achieve a high data rate with a relative low power level. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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随着无线移动通信系统的飞速发展,无线通信网络能耗急剧增加,基于中继协作技术的绿色无线通信研究受到众多研究者的关注.针对基于认知的中继协作系统,提出了一种以最大主系统能效为目标的中继分配算法.该算法在不影响主系统性能基础上,对主系统请求次系统用户作为中继转发数据,且共享主用户频谱进行了简要介绍.算法中次系统通过最大权重匹配方法为主系统分配中继（次用户）,在满足主系统能效最大化的同时,实现了次系统与主系统的频谱共享.对算法进行仿真验证,提出的算法能获得较高的主系统能效,同时提高了整个系统的频谱利用率. 相似文献
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设备间通信(D2D通信)通过复用蜂窝通信的频带资源,可以使近距离的用户直接通信,而无需通过基站进行中继.它的引入可以提升用户的服务质量,降低终端能耗,拓展小区的覆盖范围.特别的,在CDN场景中,可通过移动中继向请求相同业务内容的用户进行D2D广播传输.但是,在上述场景中,需考虑到移动终端(MT)的能耗和与蜂窝用户之间的同频干扰问题.基于此,提出了一种基于粒子群优化(PSO)算法的联合中继节点选择和功率控制机制来最小化移动中继的总能耗并同时保证两类用户的服务质量(QoS)需求得到满足.通过仿真,此方案效果得到了验证. 相似文献
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本文研究两跳协作多中继正交频分复用(OFDM)系统的网络寿命优化问题.为使网络寿命最大化,基于对节点能量的定价提出一种穷举算法,即首先列举所有的子载波配对与中继选择联合决策;在每种决策下利用拉格朗日法求解最优功率分配,使得网络在满足一定吞吐量的前提下消耗能量总价值最小;然后选择损耗能量价值最小的联合决策.由于穷举算法受到计算复杂度的限制,进而基于子载波的单位信噪比(SNR)代价将中继选择与子载波配对分步优化,提出两种低复杂度算法.仿真结果表明,本文各算法的网络寿命性能比已有算法均有显著提高. 相似文献
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针对在蜂窝系统下引入设备到设备（D2D）通信导致的干扰和能量消耗问题,文章提出首先将D2D通信技术与全双工传输技术相结合,构造一个全双工D2D通信链路场景。然后,在满足用户最小速率要求和功率阈值的条件下,分别解决了功率控制和资源分配问题,以提高全双工D2D通信链路的能量效率。最后,利用序列二次规划算法解决功率控制问题;利用所提出的自适应禁忌搜索算法解决最优资源分配问题。仿真结果表明,与现有算法相比,文章所提算法具有有效的搜索算子和扰动机制,并能以较低的计算复杂度来解决全双工D2D通信链路能效优化问题。 相似文献
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针对蜂窝网中某一基站处于体眠状态时引起各用户的通信中断问题,提出利用中继协作通信实现跨小区多跳通信的迭代中继选择算法.该算法是在有多个中继节点可为目的节点提供协作中继时,将源节点到目的节点的数据传输分为3个连续时隙,选择满足目的节点信噪比最大化的中继,以协作效率为依据删除协作效率最小的中继节点,从而逐次优化中继选择结果.仿真结果表明,该算法在跨小区多跳的通信过程中,能选择出协作效率最高的中继节点,减少协作中继的数量,可以减少中继对能源不必要的消耗,改善小区内中继协作效率,在多跳的过程中节省源节点的发射功率,从而达到能效优化的目的. 相似文献
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Jun Peng Shuo Li Chaoliang Zhu Weirong Liu Zhengfa Zhu Kuo‐chi Lin 《Wireless Communications and Mobile Computing》2016,16(8):977-991
Introducing orthogonal frequency division multiplexing (OFDM) into cognitive radio (CR) can potentially increase the spectrum efficiency, but it also leads to further challenges for the resource allocation of CR networks. In OFDM‐based cognitive relay networks, two of the most significant research issues are subcarrier selection and power allocation. In this paper, a non‐cooperative game model is proposed to maximize the system throughput by jointly optimizing subcarrier selection and power allocation. First, taking the direct and relay links into consideration, an equivalent channel gain is presented to simplify the cooperative relay model into a non‐relay model. Then, a variational inequality method is utilized to prove the existence and uniqueness of the Nash equilibrium solution of the proposed non‐cooperative game. Moreover, to compute the solution of the game, a suboptimal algorithm based on the Lagrange function and distributed iterative water‐filling algorithm is proposed. The proposed algorithm can jointly optimize the process of subcarrier selection and power allocation. Finally, simulation results are shown to demonstrate the effectiveness of the proposed joint subcarrier selection and power allocation scheme. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Shang‐Juh Kao Sin‐Yu Luo Ming‐Tsung Kao Fu‐Min Chang 《International Journal of Communication Systems》2019,32(6)
Using full‐duplex relaying in device‐to‐device (D2D) communication, spectrum efficiency can be further improved as compared with traditional half‐duplex relaying. Due to the increasing demands for more system capacities and higher data rate, a throughput‐guaranteed and power‐aware relay selection mechanism is essential so that services can be successfully accomplished within tolerable power consumption. It is also imperative to prevent cellular users from interfering and preserve resources for more users at the same time. In current paper, we proposed an efficient relay selection scheme with subchannel reusing. Using the nonconflict group discovery algorithm, firstly, we divided D2D pairs into different groups based on the neighbor lists of all the devices. The D2D pairs in the same group were considered nonconflictive. By building a matrix that represents the power consumption of D2D transmission peers through relays, we proposed a group‐oriented relay selection scheme based on the Hungarian method allowing subchannel reuse over relay‐assisted D2D networks. Applying this mechanism, different D2D pairs are able to transmit messages at the same subchannel, whenever they are in the same group. Better throughput and spectrum usage than currently available relay selection schemes without subchannel reusing can be obtained. Particularly, more D2D pairs in high dense networks can be accommodated, and spectrum resources can be better preserved. The simulation results showed that our proposed mechanism can improve the total throughput by up to 35% as compared with an existing relay selection scheme without subchannel reusing, called as PRS‐D2D, when most D2D pairs are in a few groups. 相似文献
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Bin Han Mugen Peng Yuwei Jia Wenbo Wang 《Wireless Communications and Mobile Computing》2015,15(1):30-42
This paper studies optimal resource allocation for multiple network‐coded two‐way relay in orthogonal frequency division multiplexing systems. All the two‐way relay nodes adopt amplify‐and‐forward and operate with analog network coding protocol. A joint optimization problem considering power allocation, relay selection, and subcarrier pairing to maximize the sum capacity under individual power constraints at each transmitter or total network power constraint is first formulated. By applying dual method, we provide a unified optimization framework to solve this problem. With this framework, we further propose three low‐complexity suboptimal algorithms. The complexity of the proposed optimal resource allocation (ORA) algorithm and three suboptimal algorithms are analyzed, and it is shown that the complexity of ORA is only a polynomial function of the number of subcarriers and relay nodes under both individual and total power constraints. Simulation results demonstrate that the proposed ORA scheme yields substantial performance improvement over a baseline scheme, and suboptimal algorithms can achieve a trade‐off between performance and complexity. The results also indicate that with the same total network transmit power, the performance of ORA under total power constraint can outperform that under individual power constraints. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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In this article, the problem of joint relay assignment and energy‐efficiency maximization (J‐RA‐EE‐MAX) in energy‐harvesting downlink (DL) and uplink (UL) clustered nonorthogonal multiple‐access (NOMA) networks is considered. Specifically, the aim is to perform relay assignment to user clusters in the DL and UL directions, while simultaneously maximizing energy efficiency (EE) over each relay via multiobjective optimization, and satisfying users' quality‐of‐service (QoS) constraints. However, problem J‐RA‐EE‐MAX happens to be nonconvex in each link direction, and thus is computationally prohibitive. Alternatively, a low‐complexity solution procedure is devised to solve problem J‐RA‐EE‐MAX in each link direction by: (i) optimally solving the energy‐efficiency maximizing power allocation (EE‐MAX‐PA) for each (user cluster, relay) combination to construct the relays' preference profile, and (ii) performing relay assignment via Gale's top trading cycles (TTC) matching mechanism. In particular, the optimal solution of the EE‐MAX‐PA problem is obtained by transforming it into a concave maximization problem, while the TTC mechanism is executed in linear time‐complexity so as to obtain a stable relay assignment. Simulation results are presented to validate the proposed solution procedure, which is shown to yield comparable user cluster sum‐rate and relay EE to the J‐RA‐EE‐MAX scheme, and superior to other schemes in both link directions, however, at lower computational complexity, while satisfying users' QoS constraints. Finally, this work sheds light on the importance of decoupling relay assignment in the DL/UL directions, which significantly improves user cluster sum‐rate and relay EE in comparison to coupled relay assignment schemes, and thus serves the requirements of 5G networks and beyond. 相似文献
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The communication reliability and distance of the low‐voltage power line communication system are seriously affected by the channel interference and the time variant load impedance. Therefore, how to control the relay nodes to reduce the communication delay and improve the communication reliability is mainly considered in the design. A novel hybrid relay control mechanism (HRCM) that includes the static relay pre‐configuration and the dynamic relay selection is designed for the ribbon topology in the low‐voltage power line communication networks. In the ribbon topology, the initial configuration for the communication link is realized through the pre‐configure relay nodes, which guarantees that the concentrator can communicate with the furthest terminal node. During the normal operations, the dynamic relay node is selected according to the sequence number of the uplink or downlink data frame and the data discard strategy. With the relay node dynamical selected mechanism, the frame repeated transmission can be avoided and the communication delay is reduced. The actual test results show that the hybrid relay control mechanism can effectively extend the communication distance, improve the communication real‐time and the reliability of the low‐voltage power line communication. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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针对无线功率传输技术的能量收集效率有限造成信噪比下降进而引发通信中断率增加的问题,在能量收集多跳D2D(Device to Device)无线传感网络中,提出一种基于改进K-means聚类的中继选择方法。首先,推导得到能量收集下的信噪比因子,使其作为K-means聚类特征。然后,利用最小欧氏距离原则得到距离聚类中心最近的实际节点的位置。最后,根据距离重排序得到中继节点,形成从源节点到目的节点的通信链路。仿真实验结果表明,相比最短路径算法和随机中继协作方案,所提出的改进算法链路信噪比更大,能够减小通信中断率,具有更好的中继性能。 相似文献