全双工窃听者主动干扰的协作NOMA网络性能分析

研究了瑞利衰落信道下协作非正交多址系统的安全性能。通信过程由一个时隙构成,源节点向中继广播叠加信号,全双工中继使用串行干扰消除技术解码信号协助用户通信。假设存在潜在全双工主动窃听者,窃听者能够从中继处截获信息并同时向用户发送人工噪声进行干扰。基于上述假设,在高信噪比条件下,推导了安全中断概率的近似表达式,分析了各节点传输信噪比与功率分配因子对系统中断概率的影响,分析结果与蒙特卡洛仿真结果吻合。     

Secrecy Outage Performance Analysis of DF Cognitive Relay Network With Co-channel Interference

Wireless Personal Communications - In this paper, we investigate the secrecy outage performance of the decode-and-forward cognitive relay network with the existence of the co-channel interference,...     

空时Rake MMSE合并结构的窄带干扰抑制性能分析

对多径衰落信道条件下空时rakeMMSE合并结构的窄带干扰抑制性能进行了分析,结果表明相比其它空时rake合并结构,MMSE合并结构具有最优的抑制窄带干扰和对抗信道多径衰落的性能,它受干扰功率的影响较小,而且该种合并结构仅需较少的接收天线即能获得较好的性能。     

Analysis of the Narrowband Interference Effect on OFDM Timing Synchronization

In OFDM systems, the symbol timing synchronization is needed to find an estimate of where the symbol starts. The most popular of the pilot-aided timing estimators is the one proposed by Schmidl and Cox (S&C) ["Robust Frequency and Timing Synchronization for OFDM," IEEE Transactions on Communications, vol. 45, no. 12, pp. 1613-1621, Dec. 1997]. Generally, the proper action of the timing estimator may be strongly affected by the presence of disturbances, like narrowband interference (NBI) signals. This paper investigates the effect of NBI signals, which may arise in the OFDM band as the spectrum becomes more crowded, on the timing synchronization for OFDM systems. The performance of the S&C symbol timing synchronizer is evaluated in an analytical way in the presence of narrowband interferers. Also, the probabilities of both missing and false detection of a training sequence are addressed. Further, simulations have been carried out to verify the validity of the approximations in the analysis.     

不同频率位置的窄带干扰对DSSS通信性能的影响分析

衡量窄带干扰抑制算法性能高低的一个主要标准是评估干扰处于最恶劣频率位置时的干扰输出平均功率的大小。在扩频序列周期很长且严格平衡的理想条件下,最恶劣干扰的频率位置为DSSS信号载波频率。基于典型的m序列DSSS系统,分析了处在不同频率位置的窄带干扰对DSSS系统的影响,所得结果与理想条件有所不同,这对于扩频系统的设计与应用具有指导意义。     

多用户调度在中继网路中的安全性能分析

无线通信系统中,多用户调度能够有效提高系统频谱的利用效率和吞吐量,从无线通信的物理层安全角度出发,分析了多用户调度在无线通信网络中安全性能,考虑了一种最坏通信场景,即窃听者不但从普通用户而且也从中继节点来窃听被传送的信息,在此基础上提出了一种有效的用户调度算法并得到理论表达式,最后通过仿真实验来分析安全中断概率和信息传输速度以及传输能量的关系,仿真结果表明:该理论表达式的正确性即理论表达式与蒙特卡罗仿真一致;改进的调度方法相对传统的多用户轮询调度方式有显著的优点,降低了通信系统的安全中断概率,有效提高了系统的通信安全。     

Performance Analysis on Two-Way Relay System with Co-Channel Interference

In this paper, we investigate the performance of two-way relay system with co-channel interference in a Rayleigh fading environment. Due to the mathematical intractability of original expression of signal-to-interference and noise ratio (SINR) induced by the bi-directional forwarding, a couple of effective bounds are derived for important performance metrics such as outage probability and average bit error rate of modulation, with application of diverse physical layer network coding (PNC) schemes of two time slot (2TS) and three time slot (3TS). Some asymptotic solutions are also proposed to intuitively exhibit the trends of performance in high SINR regime. We demonstrate that the performance bounds have practical meaning corresponding to different forwarding capability of the relay. Numeric simulations validate our analysis by showing that the theoretic bounds match well with simulation results. Additionally, the effect of distance between relay and sources is discussed in our interference scenario, as well as the impact of relay’s power allocation factor in 3TS PNC scheme.     

基于自能量回收的全双工用户协作NOMA系统性能分析

自干扰的存在是全双工(Full Duplex,FD)用户协作中继系统中的不利因素,本文研究了基于自能量回收(Self-Energy Recycling,SER)的FD用户协作非正交多址(Non-Orthogonal Multiple Access,NOMA)中继系统,在FD用户中继处考虑了不同的转发协议以及同时的信息和...     

Performance of an Ultra-Wideband Communication System in the Presence of Narrowband BPSK- and QPSK-Modulated OFDM Interference

An analysis is derived for calculating the bit-error probability of an ultra-wideband (UWB) communication system operating with binary phase-shift keying and quaternary phase-shift keying narrowband interference in additive white Gaussian noise. The analytical expressions are valid when phase transitions of the interfering symbols can be ignored. The accuracy of the Gaussian approximation is assessed, and several modulation schemes proposed for UWB communication are evaluated in terms of capability of interference suppression.     

Transmit Antenna Selection with Optimum Combining for Aggregate Interference in Cognitive Underlay Radio Network

Transmit antenna selection (TAS) is most popular technique in underlay cognitive radio (CR) networks as they increase the capacity of secondary users with less hardware requirements. In this paper, a new scenario of CR ad-hoc network topology is proposed in which apart from primary users, there are multiple number of secondary users which are assumed to be distributed as homogeneous spatial Poisson point process (PPP) and are trying to use the primary spectrum in underlay mode. These multiple secondary transmitters generate the aggregate interference and can degrade the performance of secondary receiver. Here this aggregate interference is estimated and its impact on performance of secondary receiver under unconstrained mode of operation is presented. Further, to enhance the performance of secondary receivers in this scenario, single TAS technique based on maximizing the received signal to interference noise ratio by using optimum combining (OC) method is proposed. Furthermore, in this work the design of end to end Simulink based environment for secondary trans–receiver system with advancements in channel design and estimation is proposed. The bit error rate (BER) analysis is presented and verified for image data for single TAS-OC technique for unconstrained mode in underlay CR network in Rician fading channel. The BER performance is also presented for different number of secondary interference sources which are located at fixed distance in one case and they are assumed to be distributed as PPP in another case.     

基于NOMA的协作中继网络安全性能分析

由于非正交多址接入(Non-orthogonal Multiple Access,NOMA)能够显著提升系统的频谱资源利用率,在下一代移动通信中得到广泛应用.对NOMA环境下多中继协作网络的最优中继选择方案和系统安全性能进行了分析和讨论,其中包含窃听者仅窃听中继和窃听者同时窃听中继及源节点这2种情况下的系统安全性能表现...     

Improving Efficiency of Resource Usage in Two-Hop Full Duplex Relay Systems based on Resource Sharing and Interference Cancellation

This letter presents a new full duplex relay (FDR) system that features more efficient use of time resource and antennas. The proposed FDR system is constructed based on timeand antenna-sharing and elimination of underlying interference. The underlying interference caused by time- and antenna-sharing is eliminated using precoding. We propose a design for the precoder and decoder, and investigate the achievable rate of the proposed FDR system when the precoder and decoder are applied. Simulation results show improved achievable rate and BER performances with the proposed FDR system compared to half duplex and conventional full duplex relay systems.     

Performance Analysis of Narrowband Interference Suppression in Orthogonal Code ModulationSpread Spectrum System

1IntroductionInaspreadspectrumsystem,theuser'ssignalisspreadtoawidebandsignalfortransmission,thenthereceivedsignalswillbedecorrelatedbacktotheoriginalone.Theprocessinggainresultedfromthisprocessprovidestheadvantagesofperformanceimprovementtocombatint...     

Amplify-and-Forward Cooperative OFDM with Multiple-Relays: Performance Analysis and Relay Selection Methods

In this paper, we investigate a cooperative system with multiple relays and amplify-and-forward relaying over frequency-selective channels. To extract the available multipath diversity, we employ orthogonal frequency division multiplexing (OFDM) with precoding. Through the derivation of pairwise error probability (PEP), we demonstrate that PEP is not a simple exponential function of the signal-to-noise ratio (SNR), but it includes a term that involves some power of logarithm of the SNR. If that term is ignored, the diversity order is given by the summation of the channel length in the direct link and the minimum of channel lengths in each relaying link confirmed by simulation results. Based on the PEP expression, we also propose two relay selection strategies; one is on a per-subcarrier basis and the other is on an all-subcarrier basis. Our simulation results indicate that both strategies result in performance improvements although the per-subcarrier method performs better.     

Performance Analysis of Soft-Bit Maximal Ratio Combining in Cooperative Relay Networks

In digital cooperative relaying, signals from the source-destination and relay-destination links are combined at the destination to achieve spatial diversity. These signals may not necessarily belong to the same modulation scheme due to the varying channel qualities of the two links. Recently, we have proposed the "soft-bit maximum ratio combiner" (SBMRC) as a low complexity diversity combining scheme for signals with different modulation levels. SBMRC exhibits BER performance that is very close to the optimal maximum likelihood detector (MLD), but with much reduced complexity. In this paper, we revisit SBMRC and provide tight lower bound for the BER performance. Since SBMRC has BER performance slightly inferior to MLD, the derived lower bound can also be used as a good approximation for the BER performance of MLD.     

OFDM系统中载波间干扰消除方法性能分析

OFDM系统面临的一个主要问题是对频率偏移的敏感性,频率偏移将导致载波闻干扰(ICI)的产生,从而大大 降低系统性能。对由频率偏移而导致的ICI进行了理论分析,并对抑止ICI的三种方法:自消除方法(SC)、最大似然估计方法 (MLE)及扩展Kalman滤波方法(EKF)进行了仿真和性能比较。     

基于OFDM技术的低压电力线通信的性能分析

OFDM技术在高速电力线通信（PLC）中的应用正成为研究热点，他成功地解决了电力线通信技术中的大部分难点。首先论述了目前高速电力线通信技术所面临的种种问题，然后介绍了电力线通信中所采用的关键技术OFDM（正交频分复用）调制技术的工作原理，并详细分析了OFDM对电力线通信系统性能的改善，最后指出OFDM是一种非常适于电力线通信的调制解调技术。     

Performance Analysis of Relay Selection with Enhanced Dynamic Decode-and-Forward and Network Coding in Two-Way Relay Channels

Wireless Personal Communications - Relay selection (RS), enhanced dynamic decode-and-forward (EDDF), and network coding (NC) have been proven to effectively improve the performance of cooperative...     

SIMO系统分集合并技术的性能分析

由于无线传输环境的复杂性,使得接收端必须采用抗信道衰落的技术,分集技术就是抗信道衰落的最有效措施之一。本文介绍了SIMO系统3种常见分集合并方式的基本原理及合并准则,分析了分集接收天线数与系统性能及系统复杂度之间的关系,并在瑞利衰落信道中采用16-QAM调制的情况下,对3种分集技术的误码率性能进行了仿真。结果表明MRC性能最好,EGC性能稍差,SC性能较差。但3种合并技术的算法复杂度正好相反,在实际应用中可根据需要进行折衷。