用于智能天线系统的多小区空时联合处理算法

TD-SCDMA系统同频组网时,邻区用户同样会产生多址接入干扰,而传统的联合检测无法消除.为了抑制邻区干扰,对上行链路接收端提出了一种将联合检测扩展到多个小区并与智能天线相结合的多小区空时联合处理算法.该算法根据对邻区用户信道估计的结果选择其中的强干扰用户,并将邻区强干扰用户和本小区用户的复合信道冲激响应同时纳入空时联合处理的系统矩阵.仿真结果表明,在室内-室外和高速车载信道模型下,采用多小区空时联合处理算法的接收机解调性能有3～4.8 dB的提升.此外,讨论了邻区相关信息的获取、邻区强干扰用户的选择和运算复杂度等具体实现时需考虑的问题.多小区空时联合处理算法可有效消除邻区强干扰用户的干扰,从而大幅提高了同频组网时系统的性能.     

基于资源调度和深度学习的5G多用户定位

由于5G通信网络具有结构异常庞大以及干扰情况异常复杂多变的特征,5G的空口资源调度面临着巨大挑战.基站准确获取用户位置不仅是许多应用场景的基本功能需求,还能指导基站在资源调度过程中有意识地规避或者抑制同频干扰,从而进一步提高系统容量.针对传统定位算法存在效率低、计算复杂度高等问题,提出利用介质访问控制(Media Ac...     

无线资源管理算法抑制TD—SCDMA同频干扰

TD—SCDMA的系统内干扰 TD—SCDMA系统的主要干扰包括公共信道干扰（TS0受干扰）、上行导频时隙干扰（UpPCH受干扰）和业务信道干扰（DPCH受干扰）。同频干扰的抑制方案如下。     

抑制LTE系统小区间干扰的软频率复用改进方案

为提高系统性能,LTE系统可通过频率复用因子（Frequency Reuse Factor,FRF）为 3的软频率复用（Soft Frequency Reuse,SFR）方案来有效抑制小区间的同频干扰,但在小 区峰值速率和系统容量方面仍有改善空间,由此介绍一种FRF为7的SFR方案,并结合与之相 适应的资源调度策略,可较大地提高小区边缘用户的峰值速率,使系统容量得以提升。     

一种适用于超密集网络下行链路的干扰抑制方案

在超密集网络（UDN）下行链路场景中,为了有效克服因节点间距减小、邻近节点传输损耗相差不大而产生多个强度相近的干扰源对用户性能的影响,提出了一种基于优先级以用户为中心的小区间干扰抑制方案。为了便于量化基站协作取得的带宽性能增益,采用了一种计算带宽盈亏率的定量分析指标。通过该指标,易于确定在特定UDN场景下干扰协调方案是否处于盈利状态,进而通过系统能够接受的最大损耗比优化参数配置。仿真结果表明,该干扰抑制方案能显著提升用户的信号干扰噪声比（SINR）性能,且能更好地保障用户公平性,有效地克服了用户SINR性能在基站数较多时受天线数限制的缺陷,为提升UDN网络用户性能和系统性能提供了一种解决方案。     

中国移动5G SA系统内同频干扰分场景优化策略研究

目前中国移动5G SA组网均采用同频组网方式,为此不可避免地会产生系统内的同频干扰,同频干扰会对网络性能、上网速率产生影响.本文介绍了当前室内外同频干扰和大气波导远距离同频干扰的优化措施和抑制方案,并进行现场验证测试,提升用户满意度.     

OFDM雷达通信一体化的同频干扰抑制技术

雷达通信一体化系统（Integrated Radar and Communication System, IRCS）可提升设备的可用性、可靠性和电磁兼容性,已成为雷达和通信交叉领域的研究热点。正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）具有高信息传输性能,且其模糊函数具有低旁瓣特性,在IRCS中得到广泛关注。在OFDM-IRCS中,组网时同频干扰严重影响雷达探测性能。针对这一问题,从信干比（Signal to Interference Ratio, SIR）分析了IRCS同频干扰特性,推导了回波信号SIR的表达式。然后,结合OFDM中交织多址（Interleave Division Multiple Access, IDMA）和干扰重构的思想,提出了基于OFDM-IDMA的IRCS同频干扰抑制算法。所提算法通过不同的交织方式区分不同IRCS节点的信号,同时利用基于干扰重构的干扰消除算法实现干扰抑制。仿真结果表明,所提算法有效地抑制了IRCS同频干扰,实现了同频干扰环境下雷达目标探测性能提升。      

一种适用于SF-OFDM系统的波束形成技术

在正交频分复用（OFDM）系统中使用空频传输分集是未来宽带无线通信中的重要技术。由于在各个终端采用多天线进行收发，导致使用空频-OFDM（SF-OFDM）传输分集的系统受到增强的共信道干扰（CCI）。本文提出了一种适用于SF-OFDM系统的波束形成方案，该方案能有效的抑制共信道干扰。在该方案中，基于盲转向的波束形成被应用于SF-OFDM系统中。分析和仿真结果表明，该方案具有良好的共信道干扰抑制能力。此外，该方案能够利用不同波达角（DOA）信号间的相对时延来增强系统性能。     

超密集Small Cell网络下TD-LTE同频干扰电源抑制方法研究

传统动态ICIC方法通过频率协调避免同一资源被调度,实现同频干扰的抑制,但是该方法在负载过高的环境下,不能完成有效抑制。针对描述的情况,融合同频干扰抑制以及数字同频干扰抑制,提出TD-LTE同时同频双工同频干扰电源抑制方法。其硬件包括数字模块、同频模块以及同频干扰重建模块,对各模块的组成结构进行设计。给出了该方法的软件流程过程。实验检测结果表明,所提方法具有较高的同频干扰抑制性能,可增加小区边缘用户的吞吐量,增强频带利用率。     

LTE-eV2X中无线电资源池共享技术研究

V2X是未来智能交通运输系统的关键技术。人们通过V2X技术获取车辆与外界之间的通信信息,提高驾驶的安全性。在业务需求不断增加的过程中,该技术也在不断演进。目前车联网网络依旧以LTE-V2X技术为主,LTE-eV2X技术是LTE-V2X发展的第二阶段,能满足更高级V2X业务的需求。其中无线电资源池共享技术可以提高资源利用率,因此受到广泛关注。本文针对不同版本、不同传输模式的用户设备,讨论了共享资源池的场景,并针对共享资源池出现的资源冲突问题,介绍了相应增强方案。     

基于SideLink的LTE-V2X联合切换方案设计

在LTE-V2X系统中,针对车载用户切换过程中蜂窝链路及SideLink(SL)链路质量不高以及SL辅助切换过程中SL链路易中断的问题,该文提出一种基于SL的联合切换方案,主要包含:联合切换流程设计、联合切换信令流程设计以及联合切换判决算法设计。首先,在联合切换流程中利用SL技术实现联合切换,并对执行联合切换的SL链路质量进行筛选,以保证联合切换的可靠性;其次,对联合切换信令流程进行了完善,以优化SL辅助切换过程中SL链路易中断问题;最后,在联合切换判决算法中将车载用户的移动方向纳入切换判决条件,从而减少不必要的切换。仿真结果显示,该文所提方案能有效提升切换成功率,与此同时还能有效减少执行LTE切换的次数。     

Interference-aware node access scheme in UAV-aided VANET

In vehicular Ad Hoc network (VANET),frequent link handovers and channel interference can lead to increased transmission delay and decreased network throughput.To address the issues,unmanned aerial vehicle (UAV) were introduced to cooperate with vehicles and construct UAV-assisted air-ground integrated VANET.An interference-aware node access scheme was proposed.The node access problem was formulated as a multi-objective optimization problem considering link transmission rate,link handovers and transmit power.Then the optimization problem was decomposed into two convex optimization sub-problems by dual decomposition method,the sub-problem jointly optimizes handovers and link transmission rate while the sub-problem optimizes the transmit power based on link reliability.Finally,simulation results show that the proposed mechanism can effectively improve data delivery ratio,average end-to-end delay and network throughput.     

An Adaptive Weighted Min-Mid-Max Value Based Filter for Eliminating High Density Impulsive Noise

In this study, non-orthogonal multiple access (NOMA) together with cognitive radio (CR) benefit to the vehicle-to-everything (V2X) as promising application with high spectrum efficiency. We have higher priority to evaluate system performance of the secondary network in such CR-NOMA system operating in the context of V2X. We first arrange vehicles belonging to serving group in this CR-NOMA assisted V2X, and it is beneficial to serve massive connections for vehicles. There are two scenarios studied in this paper, with and without the support of CR scheme. In our proposed system, two system metrics need be investigated to evaluate performance of vehicles that need higher quality of service (QoS). Our results indicate that the outage performance gap among two vehicles exists since different transmit power allocation factors were assigned to them. In particular, the outage probability is first derived in exact forms and then the bit error rate (BER) can be further achieved. In specific situations, the optimal outage probability can be obtained by numerical simulations. Simulation results are also provided to verify the correctness of the derived expressions and it exhibits advantages of the proposed CR-NOMA assisted V2X system in terms of two main metrics such as outage probability and BER.

     

Hybrid scheme for three-cell multi-user MIMO cellular networks

Orthogonal schemes are usually adopted for cell-edge users in a cellular network, where the spectrum is poorly utilized. A new interference alignment （IA） based space-division hybrid （IA-SDH） scheme is proposed by joint design transmit precoding matrices and beamforming matrices for a three-cell constant cellular network, where users at cell-center work with a conventional scheme while users at cell-edge utilize an IA scheme. Therefore, the cell-edge users suffer no interference and cell-center users are only affected by negligible inter-cell interference. Analysis simulation shows that more users can be served simultaneously than that of a conventional scheme in certain user distributions.     

室内密集型家庭基站网中自适应软频率复用技术

Femtocell networks have emerged as a key technology in residential, office building or hotspot deployments that can significantly fulfill high data demands in order to offload indoor traffic from outdoor macro cells. However, as one of the major challenges, inter-femtocell interference gets worse in 3D in-building scenarios because of the presence of numerous interfering sources and then needs to be considered in the early network planning phase. The indoor network planning and optimization tool suite, Ranplan Small- cell?, makes accurate prediction of indoor wireless RF signal propagation possible to guide actual indoor femtocell deployments. In this paper, a new adaptive soft frequency reuse scheme in the dense femtocell networks is proposed, where multiple dense femtocells are classified into a number of groups accord-ing to the dominant interference strength to others, then the minimum subchannels with different frequency reuse factors for these groups are determined and transmit powers of the grouping sub-channels are adaptively ad-justed based on the strength to mitigate the mutual interference. Simulation results show the proposed scheme yields great performance gains in terms of the spectrum efficiency relative to the legacy soft frequency reuse and universal frequency re-use.     

Parallelring: a token ring LAN with concurrent multipletransmissions and message destination removal

A token ring local area network, the parallelring, is introduced. The ability to concurrently support multiple communication paths on a single loop in an efficient and fair manner differentiates the parallelring from earlier ring architectures. This is accomplished by using a message destination removal scheme and, hence, allowing more than one station to transmit a variable-length frame at a time. Simulation studies show that the parallelring exhibits better performance in terms of throughput-delay characteristics than the other token rings. In addition, a priority scheme is used in the parallelring to provide messages of different time constraints with different media access priorities so that it can support media access fairness and real-time services. In the parallelring, error detection and recovery are completely decentralized     

Hierarchical constellation for multi-resolution data transmission over block fading channels

We propose a new technique for multi-resolution video/image data transmission over block fading channels. The proposed scheme uses an adaptive scheduling protocol employing a retransmission strategy in conjunction with a hierarchical signal constellation (known also as nonuniform, asymmetric, multi-resolution constellation) to give different transmission priorities to different resolution levels. Transmission priorities are given in terms of average packet loss rate as well as average throughput. Basically, according to the transmission scheduling and channel state (acknowledgment signal) of the previous transmission, it dynamically selects packets from different resolution levels to transmit for the current transmission. The bits from the selected packets are assigned to different hierarchies of a hierarchical 4/16-quadrature amplitude modulation to transmit them with different error protections. The selection of packets for transmission and the assignment of these selected packets to different hierarchies of the hierarchical constellation are referred to as the scheduling protocol in our proposed scheme. We model this protocol by a finite state first order Markov chain and obtain the packet loss rate and the packet transmission rate over Nakagami-m block fading channel in closed-form. Some selected numerical results show that the proposed scheme can control the relative packet loss rate and the packet transmission rate of different resolution levels by varying the priority parameter (or equivalently, the asymmetry) of the hierarchical constellation and the maximum number of allowed retransmissions.     

Dynamic queue length thresholds for multiple loss priorities

Buffer management schemes are needed in shared-memory packet switches to regulate the sharing of memory among different output port queues and among traffic classes with different loss priorities. Earlier, we proposed a single-priority scheme called dynamic threshold (DT), in which the maximum permissible queue length is proportional to the unused buffering in the switch. A queue whose length equals or exceeds the current threshold value may accept no new arrivals. We propose, analyze and simulate several ways of incorporating loss priorities into the DT scheme. The analysis models sources as deterministic fluids. We determine how each scheme allocates buffers among the competing ports and loss priority classes under overload conditions. We also note how this buffer allocation induces an allocation of bandwidth among the loss priority classes at each port. We find that minor variations in the DT control law can produce dramatically different resource allocations. Based on this study, we recommend the scheme we call OWA, which gives some buffers and bandwidth to every priority class at every port. Scheme OWA has tunable parameters, which we give rules of thumb for setting. Another scheme, called AWA, is also a good choice. It has an allocation philosophy more akin to strict priority and hence is not tunable     

Protocol design and data detection for two‐way relay networks with fractional asynchronous delays

In wireless two‐way relay systems, it is difficult to achieve perfect timing synchronization among different nodes. In this paper, we investigate relaying protocol design and data detect schemes for asynchronous two‐way relaying systems to combat the intersymbol interference caused by asynchronous transmission. We consider fractional asynchronous delays and two schemes are proposed based on cyclic prefixed single carrier block transmission, namely, the receiver frequency domain equalization scheme and relay synchronization and network coding (RSNC) scheme. In the receiver frequency domain equalization scheme, the relay simply amplifies the received signal and forwards to the two source nodes, and fractionally spaced frequency domain equalizer (FS‐FDE) is employed at the receiver to recover the transmit data. In the RSNC scheme, the asynchronous signals are resynchronized with an FS‐FDE at the relay node. The output signals of FS‐FDE are then demodulated and network coded before forwarding to the two source nodes. In this RSNC scheme, data detection at the source nodes is the same as that in synchronous networks because the asynchronous signals have already been synchronized at the relay node. Simulation results show that the performance of both schemes is almost the same as in the perfect synchronized two‐way relaying systems. Copyright © 2012 John Wiley & Sons, Ltd.