简介:InCDMAmobilecommunicationsystems,multipleaccessinterferencecanbecanceledbymultiuserdetectiontechnique.TheDegradationbychannelfadingcanbereducedbydiversityreception.Thispaperinvestigatesafamilyofmultiuserreceiversthatcombineddecor-relatingdetection,antennadiversityandRAKEmultipathdiversity.Theperformanceofthemultiuserreceiversisanalyzed.Theresultsdemonstrateasignificantincreaseintheperformanceofthereceiversbyusingmultiuserdetectionanddiversityreception.
简介:介绍了当前3G成熟的CDMA技术和未来4G的核心技术OFDM的基本原理和各自优缺点,分析了CDMA和OFDM两种不同技术的应用侧重,同时指出了两种技术融合的前景及前沿拓展。
简介:AnopticalPPM-CDMAcommunicationsystemwithanopticalhard-limiterinfrontofthecorrelatorofareceiverisproposedinordertoreducemulti-userinterference.Theperformanceofthesystemisevaluatedwhentheeffectsofbothmulti-userinterferenceandphotodetectorshotnoiseareconsidered.Anupperboundonthebiterrorrateisderived.ThecomparisonoftheperformanceoftheabovereceiverwiththatoftheopticalPPM-CDMAsystemwithoutanopticalhard-limiterismade.Simulationresultsshowthattheperformanceofthesystemwithanopticalhard-limiterissuperiortothatoftheconventionalone.
简介:摘要: 为了保证语音通话不被偷听,单独依赖一个网元的和协议的去保护做不到,整网面对的安全威胁也复杂和多变。因此,如何去端到端的方案。
简介:本文介绍了下一代移动通信系统中关键技术——正交频分复用(OFDM),它具有良好的抗多径干扰性能和高频谱利用率。然后给出多载波调制和CDMA结合的MC-CDMA系统,此系统可以支持高数据传输率和高用户容量。接着简述了可以充分利用空间资源,提高无线信道容量和信道可靠性的MIMO技术,并给出结合MIMO和MC-CDMA即MIMO-MC—CDMA系统模型,最后简要介绍了此系统中所涉及的同步及信道估计技术。