本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入...本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入链路采用OFDMA接入技术.对于BBU池到RRH,采用无线前传链路,并且部署多个IRS以增强链路传输能力.在BBU池和每个RRH发射功率约束下,本文提出通过联合优化前传链路和接入链路资源配置使下行用户和速率最大化.由于该资源配置问题是非凸的,首先采用连续凸逼近(SCA)对目标以及约束条件进行转换.其次,将转换后的问题拆分成三个子问题来交替性求解.最后,计算机仿真结果显示了所提出的联合资源分配方法与其他基准方案相比具有显著的传输性能增益.展开更多
To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal...To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access(OFDMA)and non-orthogonal multiple access(NOMA).The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units(RUs),and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency.Based on the protocol designed in this paper,in the case of imperfect successive interference cancellation(SIC),the probability of successful competition subchannels and the outage probability are derived for two scenarios:Users occupy the subchannel individually and users share the subchannel.Moreover,when two users share the channel,the decoding order of the users and the corresponding probabilities are considered.Then,the system throughput is obtained.To achieve better outage performance in the system,the optimal power allocation algorithm is proposed in this paper,which enables the optimal power allocation strategy to be obtained.Numerical results show that the larger the imperfect SIC coefficient,the worse the outage performance of weak users.Compared with pure OFDMA and NOMA,OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value.展开更多
为了提升下一代无线局域网(wireless local area network,WLAN)高密集场景下的区域吞吐量,正交频分多址接入(orthogonal frequency division multiple access,OFDMA)作为关键技术之一已被下一代WLAN通信标准采纳。然而,现有研究所提出的...为了提升下一代无线局域网(wireless local area network,WLAN)高密集场景下的区域吞吐量,正交频分多址接入(orthogonal frequency division multiple access,OFDMA)作为关键技术之一已被下一代WLAN通信标准采纳。然而,现有研究所提出的OFDMA多址接入技术均存在传输干扰扩散问题,即多个并行接入的节点位于位置分散的区域,从而对周边的传输干扰面积加大。提出一种空间聚集群组的OFDMA多址接入协议,空间位置接近的节点构成空间聚集群组,该协议使得空间聚集群组内的节点采用OFDMA的方式并行接入和传输,从而降低多个节点同时传输时的干扰范围,进而提升区域吞吐量。此外,根据网络仿真软件得出的结果,进行理论推导,理论分析与仿真结果相吻合。仿真结果表明,当小区节点数为100时,所提出协议的区域吞吐量比已有OFDMA协议和分布式协调功能协议分别提升15.98%和31.26%。为设计下一代WLAN媒体接入控制协议提供参考。展开更多
正交频分多址接入(OFDMA,Orthogonal Frequency Division Multiple Access)已经成为3G演进策略(LTE,Long Term Evolution)及4G技术的主要多址接入方式.本文研究了现有的OFDMA的切换算法,分析了其存在的不足之处.本文针对OFDMA多址技术特...正交频分多址接入(OFDMA,Orthogonal Frequency Division Multiple Access)已经成为3G演进策略(LTE,Long Term Evolution)及4G技术的主要多址接入方式.本文研究了现有的OFDMA的切换算法,分析了其存在的不足之处.本文针对OFDMA多址技术特点,提出新型的OFDMA切换算法(SBA,Sub-carriers Bidirectional Arrayed handover).并通过仿真验证新型切换算法的性能.仿真结果表明,新型OFDMA切换算法保证了用户在切换过程中的信道质量(CIR,Carrier-Interference Ratio),减少了切换信道的数目,从而提高了OFDMA系统性能.展开更多
文摘本文研究了智能反射面(IRS)辅助OFDMA(Orthogonal Frequency Division Multiple Access,正交频分多址接入)云无线接入网(C-RAN)的下行链路传输系统,其中基带处理单元(BBU)池通过多个远端射频头(RRH)与多个用户进行通信.RRH到用户的接入链路采用OFDMA接入技术.对于BBU池到RRH,采用无线前传链路,并且部署多个IRS以增强链路传输能力.在BBU池和每个RRH发射功率约束下,本文提出通过联合优化前传链路和接入链路资源配置使下行用户和速率最大化.由于该资源配置问题是非凸的,首先采用连续凸逼近(SCA)对目标以及约束条件进行转换.其次,将转换后的问题拆分成三个子问题来交替性求解.最后,计算机仿真结果显示了所提出的联合资源分配方法与其他基准方案相比具有显著的传输性能增益.
基金funded in part by the National Natural Science Foundation of China under Grant 61663024in part by the Hongliu First Class Discipline Development Project of Lanzhou University of Technology(25-225305).
文摘To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios,this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access(OFDMA)and non-orthogonal multiple access(NOMA).The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units(RUs),and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency.Based on the protocol designed in this paper,in the case of imperfect successive interference cancellation(SIC),the probability of successful competition subchannels and the outage probability are derived for two scenarios:Users occupy the subchannel individually and users share the subchannel.Moreover,when two users share the channel,the decoding order of the users and the corresponding probabilities are considered.Then,the system throughput is obtained.To achieve better outage performance in the system,the optimal power allocation algorithm is proposed in this paper,which enables the optimal power allocation strategy to be obtained.Numerical results show that the larger the imperfect SIC coefficient,the worse the outage performance of weak users.Compared with pure OFDMA and NOMA,OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value.
文摘为了提升下一代无线局域网(wireless local area network,WLAN)高密集场景下的区域吞吐量,正交频分多址接入(orthogonal frequency division multiple access,OFDMA)作为关键技术之一已被下一代WLAN通信标准采纳。然而,现有研究所提出的OFDMA多址接入技术均存在传输干扰扩散问题,即多个并行接入的节点位于位置分散的区域,从而对周边的传输干扰面积加大。提出一种空间聚集群组的OFDMA多址接入协议,空间位置接近的节点构成空间聚集群组,该协议使得空间聚集群组内的节点采用OFDMA的方式并行接入和传输,从而降低多个节点同时传输时的干扰范围,进而提升区域吞吐量。此外,根据网络仿真软件得出的结果,进行理论推导,理论分析与仿真结果相吻合。仿真结果表明,当小区节点数为100时,所提出协议的区域吞吐量比已有OFDMA协议和分布式协调功能协议分别提升15.98%和31.26%。为设计下一代WLAN媒体接入控制协议提供参考。
