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
大规模M2M(Machine to Machine,M2M)设备短时间内接入基站的现象越来越普遍。由于可用于接入的前导码(Preamble,PA)资源有限,所以大部分M2M设备在PA选择时容易发生冲突,导致随机接入失败。当冲突发生得越来越频繁时,容易造成网络拥塞。...大规模M2M(Machine to Machine,M2M)设备短时间内接入基站的现象越来越普遍。由于可用于接入的前导码(Preamble,PA)资源有限,所以大部分M2M设备在PA选择时容易发生冲突,导致随机接入失败。当冲突发生得越来越频繁时,容易造成网络拥塞。为了解决大规模M2M设备接入成功率较低的问题,提出分层接入的方法。首先确定使接入成功率最大的分组数量,使用k均值聚类方法将小区内M2M设备分为不同组,每个分组中根据最佳通信距离选择合适簇头,然后组员通过簇头接入基站。将一个接入时隙内请求接入的M2M设备在空间上分到不同分组中,可以保证在一个接入时隙中以较低的冲突概率同时完成多个接入过程。仿真结果表明,相较于非层次接入方法,使用分层接入的方法可以提高PA的传输成功率和资源利用率,从而提高大规模M2M设备的接入成功率。展开更多
机器类型通信(Machine Type Communication,MTC)在5G场景中的应用比例大幅增长。这一类型通信的主要目的是在尽可能减少人工干预的情况下,实现机器类型设备(Machine Type Device,MTD)之间的自主通信。在大规模机器类型通信(massive Mach...机器类型通信(Machine Type Communication,MTC)在5G场景中的应用比例大幅增长。这一类型通信的主要目的是在尽可能减少人工干预的情况下,实现机器类型设备(Machine Type Device,MTD)之间的自主通信。在大规模机器类型通信(massive Machine Type Communication,m MTC)场景中,随机接入(Random Access,RA)冲突是导致网络性能较差的关键因素。为了减轻RA阶段的MTD冲突,提出一种基于双队列分析模型的分布式接入控制方法。相较于中心式控制方法,分布式方法可以明显降低信令开销。此外,仿真表明,提出的方法在系统中设备数量较为稳定时具有更高的吞吐量。展开更多
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.
文摘大规模M2M(Machine to Machine,M2M)设备短时间内接入基站的现象越来越普遍。由于可用于接入的前导码(Preamble,PA)资源有限,所以大部分M2M设备在PA选择时容易发生冲突,导致随机接入失败。当冲突发生得越来越频繁时,容易造成网络拥塞。为了解决大规模M2M设备接入成功率较低的问题,提出分层接入的方法。首先确定使接入成功率最大的分组数量,使用k均值聚类方法将小区内M2M设备分为不同组,每个分组中根据最佳通信距离选择合适簇头,然后组员通过簇头接入基站。将一个接入时隙内请求接入的M2M设备在空间上分到不同分组中,可以保证在一个接入时隙中以较低的冲突概率同时完成多个接入过程。仿真结果表明,相较于非层次接入方法,使用分层接入的方法可以提高PA的传输成功率和资源利用率,从而提高大规模M2M设备的接入成功率。
文摘机器类型通信(Machine Type Communication,MTC)在5G场景中的应用比例大幅增长。这一类型通信的主要目的是在尽可能减少人工干预的情况下,实现机器类型设备(Machine Type Device,MTD)之间的自主通信。在大规模机器类型通信(massive Machine Type Communication,m MTC)场景中,随机接入(Random Access,RA)冲突是导致网络性能较差的关键因素。为了减轻RA阶段的MTD冲突,提出一种基于双队列分析模型的分布式接入控制方法。相较于中心式控制方法,分布式方法可以明显降低信令开销。此外,仿真表明,提出的方法在系统中设备数量较为稳定时具有更高的吞吐量。
