CR系统中基于微分博弈的功率控制算法

该文针对认知无线电系统动态性的特点,将微分博弈理论应用在认知无线电系统的功率控制中,建立了功率控制的非合作微分博弈模型,提出了一种基于微分博弈的分布式非合作功率控制算法。该算法在满足认知用户平均功率门限和QoS需求的基础上,实现了分布式动态功率控制,获得了反馈纳什均衡解析解。仿真结果表明,该算法可有效控制各认知用户的发射功率,增加系统吞吐量,提高系统性能。     

AMC-based resource allocation in adaptive frequency reused OFDMA-relay networks

In orthogonal frequency division multiple access (OFDMA) relay system, for supporting relay transmission, the base station (BS)-the relay station (RS) link must consume an extra part of resource, which may result in serious resource shortage. In oxder to improve resource utilization, this paper proposes a dynamic resource allocation scheme in adaptive frequency reused OFDMA-relay system based on adaptive modulation and coding (AMC) technology. In this scheme, relay nodes have two independent antennas and operate in decode-and-forward (DF) and full-duplex mode. Then the BS and RSs share the same subcarriers by spatial multiplexing by two independent antennas. The resource allocation problem is formulated for system downlink throughput maximization. Since the optimal solution couldn't be obtained easily, a sub-optimal algorithm is proposed.The adaptive frequency reused algorithm with two independent antennas RS improves the system throughput about 24.3 %compared with the orthogonal frequency allocation with single-antenna model, and increases the system throughput 10.4%compared with adaptive frequency reused algorithms with single-antenna RS. It is proved that both of the RS with two-antenna model and adaptive frequency reused scheme can improve the system throughput significantly.     

Cross-layer combining of power control and adaptive modulation with truncated ARQ for cognitive radios

To maximize throughput and to satisfy users＇ requirements in cognitive radios, a cross-layer optimization problem combining adaptive modulation and power control at the physical layer and truncated automatic repeat request at the medium access control layer is proposed. Simulation results show the combination of power control, adaptive modulation, and truncated automatic repeat request can regulate transmitter powers and increase the total throughput effectively.     

Channel-adaptive sectored multicarrier packet based systems

Multicarrier packet based multiuser systems with adaptive subcarrier-user allocation and per-user adaptive transmit-power and modulation are considered. The impact of interleaved-multicarrier cell sectoring and channel estimation errors on the performance of such a system is evaluated using computer simulation.     

基于感知无线电非合作博弈功率控制算法的研究

本文基于Goodman提出的非合作博弈功率控制模型改进了代价函数。针对感知无线电系统（CR）中各用户的通信需求,采用多载波码分多址（MC-CDMA）感知无线电系统,解决感知用户对主用户干扰和通信中断等问题,为实现感知频谱资源的有效分配,提出了一种新的感知无线电系统功率控制博弈算法。通过仿真表明,该算法同几种经典算法相比,既满足不同种类用户SIR要求,又提高了系统吞吐量,实现了对不同用户发射功率的有效控制,且系统性能明显提高。     

基于非正交多址接入系统的多用户分组优化算法

用户分组算法作为非正交多址接入(NOMA)的关键部分,对系统吞吐量和用户公平性具有重要影响。当用户数量和可用的资源增加时,用户分组的最佳调度将变得不可行,该文提出一种子带间多用户分组优化算法。该算法首先根据用户信道增益差异和子带复用用户数限制条件进行多用户初始分组处理,减小用户搜索空间,然后逐步完成初始分组用户间的优化组合,以几何平均用户吞吐量最大为用户分组准则,进一步提升小区边缘用户的吞吐量。仿真结果表明,所提算法与传统的用户分组算法相比,系统总吞吐量和几何平均用户吞吐量性能提升均超过3%。     

Adaptive Spatial Filtering for an FH/SSMA Packet Radio Network with Packet Combining

In this paper, packet throughput is analyzed and simulated for a show FH/SSMA packet radio network with adaptive antenna array and packet combining in a Rayleigh fading channel with shadowing. The packet throughput is defined as the average number of captured packets per slot. To enhance the throughput performance, an adaptive spatial filtering through adaptive antenna array and a packet combining scheme are employed. As a random access protocol, slotted ALOHA is considered, and synchronous memoryless hopping patterns are assumed. A packet consists of codewords from an (n, k) RS (Reed-Solomon) code. The tap weights of an adaptive processor is updated by RLS (recursive-least-square) algorithm. From the simulation results, it is shown that a pre-processing by adaptive antenna array and a post-processing by packet combining are very effective to improve reception performance of an FH/SSMA network.     

Throughput-Optimal Multi-Mode Precoding MIMO System with Per-Substream AMC

In this paper, we study a multi-mode quantized precoding multiple-input multiple-output (MIMO) system with per-substream adaptive modulation and coding under a maximal throughput target. An analytical throughput expression is firstly presented by recurring to Gaussian mixed approximation for block error rate of Turbo codes. An optimal mode-MCS (modulation and coding scheme) selection algorithm is then developed to achieve maximal throughput performance based on throughput criterion. Further, a complexity-reducing selection algorithm with negligible performance loss is proposed by making full use of the information provided by singular value decomposition of the instantaneous channel matrix at the receiver side. Simulation results show that both selection algorithms can achieve good throughput performance in the above mentioned MIMO system.     

Adaptive Counting Rule for Cooperative Spectrum Sensing Under Correlated Environments

We propose in this paper a dual-antenna-array (with transmitter antenna array and receiver antenna array) architecture, where the antenna elements are divided into several antenna element sets and each traffic channel is transmitted over an antenna element set, to realize the multiple traffic channels set up by a user. A SINR feedback based algorithm, which can regulate the transmission rate by iteratively adjusting the power on each traffic channel, is proposed to execute the rate control for the proposed dual-antenna-array architecture under cochannel interference. It is shown that the proposed algorithm can make the throughput meet the throughput requirement or achieve the weighted bandwidth sharing for certain fairness. In addition, we further propose a traffic channel configuration algorithm to help the SINR feedback based algorithm find the optimal traffic channel configuration that can meet the throughput requirement for each traffic channel or results in the maximal total throughput for each user.     

Analysis of an adaptive rate convolutionally coded multicarrierDS/CDMA system

The analysis of an adaptive rate convolutionally coded multicarrier direct sequence code division multiple-access (DS/CDMA) system is considered. In order to accommodate a number of coding rates easily and make the encoder and decoder structure simple, we use the rate-compatible punctured convolutional (RCPC) code. We obtain data throughputs at several coding rates, and choose the coding rate that has the highest data throughput in the signal-to-interference and noise ratio (SINR) sense. To achieve maximum data throughput, a rate adaptive system is proposed based on the channel state information (the SINR estimate). The SINR estimate is obtained by the soft decision Viterbi decoding metric. We show that the proposed rate adaptive convolutionally coded multicarrier DS/CDMA system can enhance the spectral efficiency and provide frequency diversity     

自适应遗传算法下的NOMA用户动态分簇

NOMA(Non-orthogonal Multiple Access,NOMA)系统中的用户分簇策略对系统性能有着极大的影响。该文主要研究NOMA下行链路的用户动态分簇问题,其目的是最大化系统总吞吐量。与大多数文章不同,该研究对簇中用户数以及簇个数都没有限制。遗传算法可用于优化NOMA网络中的用户动态分簇,但标准遗传算法存在收敛速度慢且容易陷入局部最优的问题。基于此,该文将自适应调节参数的改进遗传算法用于用户的动态分簇,来改善上述问题。仿真结果表明,该算法相比于穷举搜索能够有效降低求解复杂度,且系统性能明显优于固定簇分配算法及自适应配对策略下的系统性能。      

改进型自适应多叉树防碰撞算法研究

 文章在自适应多叉树防碰撞算法的基础上,通过优化阅读器所发送前缀的方法,提出了一种改进型自适应多叉树(IAMS)防碰撞算法.该算法通过计算碰撞因子来动态地选择搜索树的叉数,并对四叉树的查询前缀进行优化,从而避免了大量的空闲时隙.文章通过数学分析,准确地描述了IAMS算法识别标签所需的时隙数.仿真结果表明,改进型自适应多叉树防碰撞算法具有更快的识别速度和更高的系统吞吐率.     

一种新的MIMO无线通信系统链路自适应算法

提出并分析了一种适用于MIMO系统的新的链路自适应算法。通过接收端估计信噪比,并利用各种编码调制方式的特性,该算法在接收端采用递归的方法确定了每一个发射端子信道所采用的编码调制方式,使反向链路仅传输少量的控制信息,实现了链路的自适应。仿真结果表明,文章所提出的算法大大提高了MIMO系统的吞吐量,且可靠性也显著增加。     

认知无线电系统中一种改进的功率控制博弈算法

分布式功率控制是认知无线电(CR)系统中的关键技术之一,它直接影响到无线系统的性能。本文采用了博弈论的方法来实现对CR用户的分布式功率控制,在David Goodman的非协作博弈算法的基础上,给出了一种改进的效用函数,它使各用户在满足要求信干比条件下发送功率最小,同时使整个系统内由各种干扰引起的失真最小。本文通过理论推导证明了新的效用函数存在纳什均衡,并且均衡点唯一,同时仿真验证了该算法的收敛性,仿真结果表明这种兼顾用户自身利益以及用户间公平性的效用函数能降低发送功率,并且有效提高CR系统的性能。     

Novel Power Control Game via Pricing algorithm for cognitive radios

To compensate the service providers who have paid billions of dollars to use spectrum and to satisfy secondary users＇ requirements in cognitive radios, a Non-cooperative Power Control Game and Pricing algorithm （NPGP） is proposed. Simulation results show that the proposed algorithm can regulate the secondary users＇ transmitter powers, optimally allocate radio resource and increase the total throughput effectively.     

MIMO-OFDM系统的自适应多用户分集及性能分析

 本文建立基于随机波束成形和自适应调制的MIMO-OFDM系统的自适应多用户分集系统模型,提出随机波束成形QR接收机的自适应多用户分集资源分配算法及其简化算法,推导在最大化系统吞吐量条件下系统的误码性能.仿真结果表明该算法在用户数很小时使系统性能收敛到特征波束成形系统的性能;当用户数增多时,采用天线分配算法的多用户分集系统能获得比特征波束成形系统更好的性能;将自适应编码调制技术运用到多用户分集系统来提高系统的实际吞吐量和误码性能.     

提高卫星通信系统吞吐量的复数域网络编码算法

针对传统卫星通信系统吞吐量不高的问题,本文提出了一种基于复数域网络编码（CFNC）的卫星通信系统方案。该方案在发送前对信号进行符号级的CFNC编码,在不增加终端发射功率的情况下提供比传统卫星通信系统更高的吞吐量,并适用于多用户网络。该方案同时适用于基于处理转发器和透明转发器的卫星平台。特别是在双向卫星通信系统中,与基于伽罗瓦域网络编码（GFNC）的系统相比,本文提出的方案不仅具有更高的吞吐量而且更具有普适性。      

无线网络中基于DSDV的最大化吞吐量的协作路由算法

为最大化无线自组织网络的吞吐量,提出一种自适应的协作路由算法。在算法中,协作分集技术与路由选择相结合,通过在路由的每一跳选择最佳的中继节点协作发送节点传输信息来改善网络吞吐量。首先通过目的序列距离矢量路由协议（DSDV）初步建立最短路由路径,在每条链路的发送节点和接收节点根据邻节点表选出公共邻居节点,建立候选中继集合;进一步,每一跳根据链路吞吐量,在候选中继集合中自适应选择最多两个中继来协助发送节点进行传输,并根据选出的中继节点数动态分配节点发射功率。在保证系统发射功率一定的情况下,最大化网络吞吐量。仿真结果表明,在相同的发射功率下,相对于非协作路由DSDV算法,采用固定数量中继的协作路由算法提高了整个网络的吞吐量,而自适应的协作路由算法可进一步提高吞吐量;同时仿真了网络吞吐量与网络规模和节点最大移动速度的变化关系。      

OFDM系统中基于自适应调制和ARQ的PHY-MAC跨层设计

设计了一种适用于正交频分复用（OFDM）的跨层自适应算法。此算法结合自适应调制（AM）和有限自动重传请求（ARQ）技术，能够根据不同的信道状态在物理层和数据链路层联合进行性能优化，可以在保证上层吞吐量一定的条件下提供更小的丢包率。仿真结果表明，通过跨层结构设计的系统和传统的分层结构设计的系统相比有一定的性能增益，在进行高速传输时此增益更为显著。     

基于MIMO信道估计误差模型的功率分配与自适应调制算法

该文分析了瑞利平坦衰落信道下,信道估计误差对采用迫零接收的MIMO系统性能的影响,提出了一种以系统有效吞吐量最大化为目标的功率分配与自适应调制算法。为了减少信道估计误差对实际系统性能的影响,该算法对发送端估计的信噪比进行修正,并以此作为功率分配和自适应调制的依据。在系统总功率受限的条件下,对发端多天线的功率分配结合了空域注水定理和比特分配,并尽量保证调制阶数高的数据符号所在天线的功率。仿真结果表明,该算法实现较简单,获得的系统有效吞吐量接近于最优值,适用于实际系统。