NOMA增强型D2D通信的资源分配算法

传统蜂窝网络中,多址接入技术起着尤为关键的作用,与正交多址(Orthogonal Multiple Access,OMA)技术相比,非正交多址(Non-Orthogonal Multiple Access,NOMA)能够支持的用户数量远远超过可用正交资源的数量,可以达到更高的频谱效率和用户公平性.因此,为提高异构蜂窝网...     

Power Allocation for NOMA in D2D Relay Communications

Non-orthogonal multiple access(NOMA)is considered as one of the key technologies for the fifth generation(5G)wireless communications.The integration of NOMA and device-to-device(D2D)communications has recently attracted wide attention.In this paper,a relaying D2D communications assisted with cooperative relaying systems using NOMA(DRC-NOMA)is considered.We analyze the ergodic sum-rate for the proposed system and then derive the closed-form expressions.In addition,an optimal power allocation strategy maximizing the ergodic sum-rate is proposed based on these analysis results.Numerical results show the good agreement between the results of analysis and Monte Carlo method.The proposed DRC-NOMA has a great improvement of the ergodic sum-rate in the small regime of average channel gain of D2D pair.     

基于NOMA的D2D辅助中继系统性能分析与优化

本文针对两阶段NOMA(Non-Orthogonal Multiple Access)-D2D((Device-to-Device)辅助中继场景提出了一种功率优化算法，推导分析了各用户的中断概率。构建了以最大化系统各态历经容量为目标的优化问题，由于一、二两阶段通信用户的差异性，重点优化了对提升系统容量起决定作用的第一阶段功率分配因子，分析证明了原优化问题存在极值点，并利用凸函数性质获得了优化的功率分配因子，并且进一步推导分析了各个用户的中断概率。仿真结果表明，理论推导的中断概率值与仿真结果完全一致，证明了推导的正确性，本文提出的功率优化算法能显著提高系统容量，且降低了中断概率。例如当SNR为35dB时，本文算法可以提高约17.6%的系统容量，而作为辅助中继用户的中断概率大约降低了81.3%。      

Controlled Growth of Layered Silver Stéarate on 2D and 3D Surfaces

This investigation confirms that silver stearate consists of an infinite‐sheet, two‐dimensional, nonmolecular layered structure. Scanning electron microscopy, X‐ray diffraction, and infrared spectroscopy reveal the following: plate‐like morphology is identified from the SEM image, XRD peaks can be indexed to the (0k0) reflections of a layered structure, and infrared peaks show that alkyl chains are present in an all‐trans conformational state with little or no significant gauche population. Based on these structural characteristics, we demonstrate that silver stearate, a prototype of layered organic‐inorganic hybrid material, can be grown not only in a designed two‐dimensional pattern but also in three‐dimensionally ordered ways by using carboxyl‐group terminated nanoparticles as a template.     

Soft Decision Error Assisted Layered Multiuser Detectors for MIMO 2D Spread MC DS-CDMAs

In this paper, we present two layered multiuser detectors (MUDs) for MIMO frequency-time-domain (FT-domain) multi-carrier (MC) direct sequence code division multiple access (DS-CDMA) systems with an antenna array at the base station. We assume that multiple users are active and individually utilize multiple transmit antennas in the MC DS-CDMA system. The users are organized into groups, and each user is assigned a unique Time-domain (T-domain) signature code. Moreover, users in the same group share a unique F-domain signature code. As a result, they can exploit the T-domain and F-domain signature codes to spread their multiple symbols in parallel, and then transmit the FT-domain spread signals from the corresponding multiple antennas over the fading channels to the base station. However, because of the non-ideal channel effect and/or the use of non-orthogonal signature codes, the FT-domain spread MC DS-CDMA system is affected by multiple access interference (MAI) in the same way as CDMA-like systems. To mitigate the effects of MAI and improve the system’s performance, we propose two layered MUDs that exploit the layered soft decision errors. Specifically, in a trade-off between the performance and the computational complexity, only the soft decision errors of one user/one group are used in the proposed layered MUDs. The results of simulations and a complexity analysis demonstrate that the proposed layered MUDs outperform existing approaches and the computational complexity is modest.     

New NOMA power allocation strategy

Non-orthogonal multiple access(NOMA) has been widely used in the research of the fifth generation communication,due to the advantages of improving the spectrum efficiency and data rate.In order to guarantee the service of users,a new power allocation strategy was proposed to improve the fairness of users in the cell edge.According to the proportional fairness method,the goal was to maximize the proportionality fairness factor among the users with the least fairness in multiplexed users.The nonconvex objective function was transformed into convex function,and the optimal solution of problem was obtained by KKT optimal constraint condition.Simulation results show that the new NOMA-based power allocation strategy proposed outperforms the traditional orthogonal multiple access technology (OMA).     

Buffer-aided cooperative NOMA with partial relay selection

Telecommunication Systems - The Cooperative Non-orthogonal multiple access (C-NOMA) technique has been considered as a promising solution to improve the coverage extension and transmission...     

Ambient Backscatter Communications over NOMA Downlink Channels

In this paper,we investigate the performance of commensal ambient backscatter communications(AmBC)that ride on a non-ortho go nal multiple access(NOMA)downlink transmission,in which a backscatter device(BD)splits part of its received signals from the base station(BS)for energy harvesting,and backscatters the remaining received signals to transmit information to a cellular user.Specifically,under the power consumption constraint at BD and the peak transmit power constraint at BS,we derive the optimal reflection coefficient at BD,the optimal total transmit power at BS,and the optimal power allocation at BS for each transmission block to maximize the ergodic capacity of the ambient backscatter transmission on the premise of preserving the outage performance of the NOMA downlink transmission.Furthermore,we consider a scenario where the BS is restricted by a maximum allowed average transmit power and the reflection coefficient at BD is fixed due to BD’s low-complexity nature.An algorithm is developed to determine the optimal total transmit power and power allocation at BS for this scenario.Also,a low-complexity algorithm is proposed for this scenario to reduce the computational complexity and the signaling overheads.Finally,the performance of the derived solutions are studied and compared via numerical simulations.     

Theoretical Analysis of NOMA Within Massive MIMO Systems

Wireless Personal Communications - Non-orthogonal multiple access (NOMA) and massive multi-input multi-output (MIMO) have both been proposed for achieving spectrum efficiency and energy efficiency...     

BER Analysis of NOMA with Max-Min Relay Selection

In contrast with orthogonal multiple access(OMA) technologies,non-orthogonal multiple access(NOMA) technology can achieve higher spectral effi-ciency and suppor...     

面向用户体验的多小区混合非正交多址接入网络资源分配方法

该文研究了多小区混合非正交多址接入(MC-hybrid NOMA)网络的资源分配.为满足异构用户的服务体验,以最大化全网综合平均意见评分(MOS)累加和为目标,考虑基站选择、信道接入和功率资源分配的联合优化问题,该文提出一种用户、基站和信道3方的2阶段转移匹配算法,并根据用户MOS进行子信道功率优化.仿真结果表明所提多小区混合NOMA网络资源分配方案能有效提升全网用户服务体验和公平性.     

Outage Performance of Uplink (UL) NOMA Network

Wireless Personal Communications - This paper proposes and analyses the power allocation coefficient normalization for successive interference cancellation in power-domain non-orthogonal multiple...     

Outage Performance of Energy Harvesting DF Relaying NOMA Networks

In this paper, we investigate energy harvesting decode-and-forward relaying non-orthogonal multiple access (NOMA) networks. We study two cases of single relay and multiple relays with partial relay selection strategy. Specifically, one source node wishes to transmit two symbols to two respective destinations directly and via the help of one selected intermediate energy constraint relay node, and the NOMA technique is applied in the transmission of both hops (from source to relay and from relay to destinations). For performance evaluation, we derive the closed-form expressions for the outage probability (OP) at D ₁ and D ₂ with both cases of single and multiple relays. Our analysis is substantiated via Monte Carlo simulation. The effect of several parameters, such as power allocation factors in both transmissions in two hops, power splitting ratio, energy harvesting efficiency, and the location of relay nodes to the outage performances at the two destinations is investigated.     

智能窃听下协作NOMA网络的性能分析

针对下行双用户NOMA (Non-Orthogonal Multiple Access)系统模型中存在智能窃听者,该窃听者可以自适应地选择被动窃听或主动干扰工作模式,在不精确了解其干扰水平的情况下,部分NOMA用户很有可能遭遇传输质量下降乃至保密中断,这将对信息安全传输构成严重威胁。另外,由于信道衰落,用户的位置对系统整体性能有很大影响,难以保证距离源节点较远用户的传输质量。为解决上述问题,本文提出了一种新型的两阶段用户协作方案。第一阶段,远用户采用全双工(full-duplex,FD)干扰智能窃听者,第二阶段,近用户可作为一个中继协助源节点转发远用户信号信息,并在接收端采用串行干扰消除（Successive Interference Cancellation, SIC）技术进行解码。使用户间达成合作,提高通信链路安全性和用户服务质量。考虑到系统中不同用户的信息接收速率与通信需求不同之间的相关性,分别推导了遍历安全容量和遍历容量的解析表达式,同时分析了功率分配因子和用户间协作发射功率等因素对性能的影响,并通过Monte-Carlo仿真验证了其正确性。      

Full-Duplex Relaying Schemes for Cooperative NOMA Networks with SWIPT

Wireless Personal Communications - Existing security approaches for safeguarding data exchange among the sensor nodes are investigated in presence of apriori information of an adversary in...     

基于NOMA用户中继的卫星网络性能分析

为了满足大规模数据接入以及高通信质量的需求,文章研究了基于非正交多址接入(NOMA)用户中继协作的卫星网络,并分析了中继用户1和受助用户2的中断性能和系统吞吐量,同时也考虑了非理想信道状态信息(CSI)对系统中断性能和吞吐量的影响.最后,通过数值仿真验证了分析结果的正确性.与正交接入(OMA)策略相比,借助NOMA策略...     

Experimental Study of Constellation Rotation in NOMA Wi-Fi Networks

Journal of Communications Technology and Electronics - Non-orthogonal multiple access is promising way to increase the efficiency of Wi-Fi networks in the downlink. With this technology, an access...     

基于移动边缘计算的NOMA异构网络资源分配

以最大化缓存收益为目标,针对部署缓存的NOMA异构网络下的基站用户匹配及功率分配问题,结合消息传递及DC规划提出了NOMA联合优化算法.首先将约束条件合并到目标函数中,通过计算新的优化问题中函数节点与变量节点间消息传递的边缘得到用户协同结果;然后将原优化问题变形为2个凸函数差的形式,通过DC规划对功率资源进行分配;最后...     

Layered Sb2Te3 Nanoflakes as Chalcogenide Dielectrics

Dielectric nanoflakes of Sb₂Te₃ represent an important advance in science and technology due to their extraordinary properties. Polycrystalline layered Sb₂Te₃ nanoflakes have been successfully synthesized via a high-throughput chemical route at 60°C. The frequency and temperature dependence of the dielectric constant and dielectric loss of the layered Sb₂Te₃ nanoflakes have been measured in the frequency range from 30 Hz to 758,000 Hz and temperature range from 313 K to 373 K. As-synthesized Sb₂Te₃ nanoflakes are shown to be promising alternative dielectrics because of their high dielectric constant (ε′ ≈ 7.3 to 6022) and low dielectric loss (tan δ ≈ 0.2 to 9.2). These higher values of ε′ and lower values of tan δ of Sb₂Te₃ nanoflakes confirm that capacitors with capacity (C) of ～5.2 pF to 4336 pF may be fabricated for storing renewable energy. Raman spectroscopy confirms that the peak located at ～142 cm^?1 corresponds to one in-plane vibrational mode (E _g ² ) of layered Te–Sb–Te–Sb–Te lattice vibration.     

协作NOMA系统中的一种新型节能功率分配方案

在传统的协作非正交多址（CNOMA, Cooperative Non Orthogonal Multiple Access)系统中,通常需要向弱用户分配更多的功率,分配给强用户的功率不超过总功率的一半。同时,强用户还需在协作阶段承担中继通信的任务。上述功率分配方式必将给强用户带来一定的负担。为了在满足弱用户服务质量的情况下,进一步提高强用户的中断性能,本文提出一种基于中继和无线携能通信（SWIPT, Simultaneous Wireless Information and Power Transfer）的新型功率分配方案。该方案使用能量收集设备收集能量,通过最大化系统和速率寻求无线携能通信的最优功率分割因子,从而获得系统中断概率的闭式表达。考虑到优化问题的性质,本文提出了一种在功率分配固定的情况下,通过单调优化求解无线携能通信功率分割因子的算法。仿真结果表明,与CNOMA系统的传统功率分配方案相比,本文所提方案能够在不损失弱用户中断性能的前提下,有效提升强用户的中断概率,系统和速率总体提高了近 20%。