移动卫星通信系统中干扰抵消技术的研究

本文在对传统的并行干扰抵消ＰＩＣ算法和逐次干扰抵消ＳＩＣ算法进行了深入研究的基础上，提出了基于分组干扰抵消的ＭＩＣ算法和ＳＭＩＣ算法。其中ＳＭＩＣ算法具有计算量不大、计算时延小、硬件比较容易实现等优点。仿真结果表明，在相同传输环境下，采用ＳＭＩＣ算法的系统的误码率远低于ＳＩＣ和ＰＩＣ算法。当分组数较大时，采用ＭＩＣ算法的系统的误比特率优于ＳＭＩＣ算法，但其计算量较大。     

TD-SCDMA系统中的干扰抵消算法性能分析

分析了干扰抵消技术应用于TD—SCDMA系统的性能。建立了系统信号模型,描述了SIC、PIC、PIC-partial和ZF—PIC四种干扰抵消算法模型,并且在渐进有效性、抗远近效应和实现负责度等方面进行了性能分析比较,通过仿真分析表明PIC-partial算法比其他三种算法性能优越。     

CDMA系统中的多用户检测技术

传统的直接序列扩频－码分多址（ＤＳ－ＣＤＭＡ）通信系统中,多址干扰（ＭＡＩ）的存在制约了系统的性能和容量。一个较好的解决办法是多用户检测。集中讨论了次佳多用户检测（包括各种线性方案和非线性方案）,给出了它们的结构,分析和比较了它们的性能。最后带提出了一种结合最小均方误差（ＭＭＳＥ）检测的连续干扰扰抵消（ＳＩＣ）方案,其性能好于单一的ＳＩＣ和ＭＭＳＥ检测器。     

DS／CDMA系统中同信道干扰取消技术

在码分多址系统中，多址干扰和远近效应是影响系统性能、限制系统容量的主要因素。本文介绍了ＤＳ／ＣＤＭＡ系统中目前采用的时域和空间域数字滤波技术，然后对这两种数字滤波技术提出了自己的一些看法。     

混合干扰抵消技术在导航接收机中的应用

在扩频体制的无线电导航系统中,接收机同时会收到多个导航台发射的地波和天波信号,这样接收点同时存在天波干扰和远近效应问题。提出基于天地波识别的远近效应判定算法和混合干扰抵消方法,在捕获结果都为地波的前提下,判断是否存在远近效应,利用串行干扰抵消跟踪获得较准确的初始数据估计,在此基础上用并行干扰抵消使信息数据更加精确。分析了干扰的因素,建立了实现原理框图,从而得出系统性能。仿真结果表明,利用改进的干扰抵消技术不仅可以提高系统的识别能力,还可以提高对于导航电文的接收性能。     

W—CCMA系统中的抗远近效应技术

传统的ＣＤＭＡ接收机对多址干扰的处理不理想，因而对远近效应十分敏感。在现有的系统中采用严格的功率控制技术来克服远近效应，但由于移动通信信道的快速变化，使功率控制的方法有局限性。本文在分析了传统接收机的固有缺陷的基础上，系统阐述一些目前国内外正在研究的用于抗远近效应的多址干扰抑制技术，对其各种方案进行一定的阐述和分析。     

OFDMA系统中的干扰抵消技术研究

针对上行0FDMA系统中由于载波频率偏移所引起的子载波间干扰．提出了基于MMSE检测的串行干扰抵消技术。并对该方案与MMSE检测的误符号率性能以及抗远近效应的性能进行了比较。     

CDMA系统下行链路的干扰抵消

CDMA蜂窝移动通信系统是一种采用多址技术的通信系统，即采用不同的地址码来区分用户、基站和信道。然而由于其在多径衰落信道中的自相关和互相关特性的不理想造成了多址干扰。在扩频通信系统的下行链路中，有效地抵消多址干扰是进一步改善系统性能和提高系统容量的重要途径。本文提出一种应用于CDMA下行链路的干扰抵消算法，分析了下行链路接收机的实现原理及过程，并对其中的关键算法进行了详细地分析，仿真结果表明，所选取的下行接收算法能改善系统的性能。     

自适应部分干扰抵消多用户接收机

在DS/CDMA系统中,采用多用户检测技术可以有效地克服多址干扰(MAI,MultipleaccessInterference)及远近效应。本文提出了一种自适应部分干扰抵消(APPIC,AdaptivePartialParallelInterferencecancellation)算法,根据匹配滤波器输出的判决统计对多址干扰进行选通抵消,以提高系统性能。同时本文给出了自适应部分干扰抵消接收机的非相干实现方案,并给出了仿真结果。     

数字音频信号压缩编解码算法研究与解码软件实现

ＭＵＳＩＣＡＭ算法是当今数字音频信号压缩算法中佼佼者，本文在详述ＭＵＳＩＣＡＭ算法的基础 ，着重阐述了其第Ⅱ层算法的编解码及解码算法的具体软件实现，该软件能解所有以ＭＵＳＩＣＡＭ算法记录的音频数据，为ＭＵＳＩＣＡＭ算法在数字音频领域的应用奠定了基础。     

Analysis of a pipelined successive interference cancellation schemefor a DS/CDMA system

The bit error rate (BER) expression for a proposed pipelined successive interference cancellation (PSIC) scheme in a direct sequence/code division multiple access (DS/CDMA) system is derived analytically. The proposed PSIC scheme is a pipelined modification of a successive interference cancellation (SIC) scheme. The numerical results show that the proposed PSIC scheme outperforms the SIC scheme in viewpoints of the BER and the decoding delay performances     

同时同频全双工LTE射频自干扰抑制能力分析及实验验证

同时同频全双工本地发射信号会对本地接收信号产生强自干扰,为了使信号能够通过射频接收通道及模数转换器件,需要在射频前端进行自干扰抑制。在自干扰为直射路径的条件下,该文采用直接射频耦合法,对长期演进(LTE)同时同频全双工自干扰抑制进行实验测试;分析推导了自干扰功率、带宽及线缆、幅度、相位调整误差对射频自干扰抑制能力的影响;得到了射频自干扰抑制能力的闭合表达式。分析表明对于20 MHz带宽,-10 dBm接收功率的LTE射频自干扰信号,理论上能抑制54 dB的射频自干扰,而实验测试结果表明能抑制51.2 dB。     

SAR内定标技术和内定标精度分析

分析了SAR内定标技术与内定标精度分析.讨论了SAR集中收发式的内定标技术,推导内定标状态下系统总功率和总功率变化量的表达式、系统增益和系统增益变化量的表达式;SAR内定标信号的处理;SAR内定标精度分析;最后完成对某地区SAR图像数据的灰度校正.     

Projected block-wise SIC detection for communication systems with non-negativity constraints

Photonic Network Communications - Recently, a number of projected successive interference cancellation (PSIC) and projected parallel interference cancellation (PPIC) structures, which make use of...     

采用串行干扰消除技术的多速率单小区CDMA系统性能分析

串行干扰消除(SIC)技术可以有效抑制多址干扰(MAI),显著提高DS-CDMA系统容量。该文针对单小区DS-CDMA移动通信系统的上行链路,推导出在加性高斯白噪声信道条件下,采用匹配滤波器的传统单用户接收机双速率系统、线性SIC双速率系统以及理想SIC双速率系统的容量极限,并给出了数值结果。研究结果表明,在任何条件下,相对于传统的单用户接收机系统,采用线性SIC技术能显著提高系统容量。另外,随着系统中用户数目的增多,理想SIC和线性SIC的接收功率之间的差异越来越大,因此,对实际的多速率SIC系统进行功率分配时,不能简单地用理想SIC模型来替代实际的线性SIC系统,以免系统性能严重恶化。     

基于有界成分分析的带内全双工数字自干扰抵消

凭借能够提升频谱利用率的优势,带内全双工(In-Band Full Duplex, IBFD)技术有望成为现代无线通信系统的潜在方案。然而,在应用过程中却面临自干扰抵消(Self-Interference Cancellation, SIC)的巨大挑战。SIC可以从空域、模拟域和数字域3个方面来单独或组合实现。该文重点研究了IBFD数字SIC。针对传统数字SIC性能受到收发链路器件非理想因素限制的问题,该文建立了一种射频辅助链路的IBFD系统,利用有用信号和自干扰信号的有界性,设计了一种基于有界成分分析的数字SIC方法。在视距(Line Of Sight, LOS)和非视距(Non-Line Of Sight, NLOS)两种信道场景下,利用仿真和实测数据进行了验证分析。结果表明,相比较于最小二乘方法和独立成分分析方法,所提有界成分分析方法改善了SIC效果,并提高了系统误码率性能。     

Successive interference cancellation in multicarrier DS/CDMA

In this paper, we present a successive interference cancellation (SIC) scheme for a multicarrier (MC) direct-sequence code-division multiple-access (CDMA) system, using band-limited spreading waveforms to prevent self-interference. In every subband, the SIC receiver successively detects the interferers' signals and substracts them from the user-of-interest. A comparison is made among SIC, a minimum mean-squared error (MMSE) receiver, and matched filter (MF) detection with maximal-ratio combining (MRC). We also consider suboptimal combining using pilot symbol-assisted modulation (PSAM) to make the system more realistic. Analytic bit-error probabilities for SIC, MMSE, and MF in correlated Rayleigh fading channels are derived. The theoretical results for SIC, MMSE, and MF are shown to agree well with simulations. In particular, SIC and MMSE are shown to achieve better performance than MF with MRC; when the number of users is small, SIC provides better performance than does MMSE. Further, the correlation among different subcarriers is studied, and only large subcarrier correlation coefficients result in an obvious worsening of performance. Finally, we derive results for the performance degradation that an SIC scheme experiences in MC CDMA due to phase and timing tracking errors. It is shown that SIC can still retain a performance advantage over MF-MRC, although the advantage of SIC decreases with increasing tracking errors, especially when subcarrier correlation coefficients are small     

Ku波段宽带高增益基片集成腔圆极化阵列天线北大核心CSCD

提出了一款应用于Ku波段的宽带高增益基片集成腔(Substrate Integrated Cavity,SIC)圆极化阵列天线。通过引入沿SIC口径面对角线放置的一对半月形寄生贴片和SIC底部馈电纵缝,使SIC中的TM_(211)和TM_(121)谐振模式幅值相等、相位相差90°,产生高增益圆极化辐射。同时,双寄生贴片还引入了一种背腔缝隙耦合振子圆极化辐射模式,扩宽了天线高增益圆极化辐射带宽。在此基础上,设计了一款2×2单元顺序旋转馈电的SIC圆极化阵列天线。阵列天线采用双层基片集成波导顺序相移馈电网络进行馈电,进一步增大了天线的圆极化带宽。综合考虑天线的-10 dB反射系数带宽、3 dB轴比带宽和3 dB增益带宽,测试结果表明,圆极化阵列天线的有效带宽为10.74-13.30 GHz(21.3%),在通带范围内最大增益为14.50 dBi。     

On the integration of SIC and MIMO DoF for interference cancellation in wireless networks

Recent advances in MIMO degree-of-freedom (DoF) models allowed MIMO research to penetrate the networking community. Independent from MIMO, successive interference cancellation (SIC) is a powerful physical layer technique used in multi-user detection. Based on the understanding of the strengths and weaknesses of MIMO DoF and SIC, we propose to have DoF-based interference cancellation (IC) and SIC help each other so that (i) precious DoF resources can be conserved through the use of SIC and (ii) the stringent SINR threshold criteria can be met through the use of DoF-based IC. In this paper, we develop the necessary mathematical models to realize the two ideas in a multi-hop wireless network. Together with scheduling and routing constraints, we develop a cross-layer optimization framework with joint DoF IC and SIC. By applying the framework on a throughput maximization problem, we find that SIC and DoF IC can indeed work in harmony and achieve the two ideas that we propose.     

Throughput analysis of a CSMA based WLAN with successive interference cancellation under Rayleigh fading and shadowing

In this paper, we consider a carrier sense multiple access based wireless local area network (WLAN) with a successive interference cancellation (SIC) technique. We develop an analytical model to compute the average throughput of a user in a WLAN with the SIC technique in presence of path loss, Rayleigh fading and log-normal shadowing. We then validate the model via simulation. By means of the developed analytical model, we compute the average throughput of a user in WLAN systems without and with the SIC technique and evaluate the throughput gain provided by the SIC technique. We find that the throughput gain provided by the SIC technique is significant. However, the throughput gain varies significantly depending on the parameters of network and wireless channel. We find that the throughput gain provided by the SIC technique increases with increasing the number of users in WLAN, medium access rate of the users and the variance in shadowing and it decreases with increasing the data transmission rate. We also investigate the effect of the decoding capability of the SIC technique on the throughput performance. We find that throughputs obtained with decoding capability of 2 and 3 packets are very close.