缓冲辅助的中继系统链路选择技术研究

发布时间：2018-07-02 07:09

本文选题：缓冲辅助中继 + 中继选择　；参考：《电子科技大学》2014年硕士论文

【摘要】：中继技术已经成为当前以及未来移动通信系统中的一项重要技术。传统的半双工中继传输技术都是基于中继处前一个时隙收后一个时隙发这样交替进行的模式。但传统中继传输模式受信道状况的影响较大,即当中继收、发两条链路其中任意一条链路的信道状况比较差时,中继处这样的固定传输模式都将使得系统难以取得较为理想的性能。缓冲辅助的中继传输技术,即给予中继一定的存储与缓冲空间,使得中继可以不用再遵循一收一发的固定传输模式,而是让中继在收、发信息的同时拥有了更多的自由。系统可以根据同一时隙不同链路信道状况的好坏,以及一定的选择算法自适应地选择链路传输信息。缓冲辅助中继技术的提出,打破了原有固化的中继传输机制,为中继传输技术方面的研究开辟了新的领域。本文主要研究了缓冲辅助的中继传输技术,缓冲辅助的中继传输技术根据中继节点数量的不同主要有两种应用,即针对多中继节点模型下的中继选择技术,与单中继节点模型下的链路选择技术。首先,针对多中继系统,本文给出了缓冲辅助的中继选择技术,即被选择用来接收信息的中继可以将信息存储在缓冲中直到它下次被选中用来发送信息时再转发出去,可以使得系统总是可以在前一个时隙选择最优的信源-中继链路传输信息,在后一个时隙选择最优的中继-终端链路转发信息。针对无限的缓冲空间,给出了最佳最佳中继选择(Max-Max Relay Selection,MMRS)算法,针对有限的缓冲空间,给出了混合中继选择(Hybrid Relay Selection)算法。通过推导中断概率,得到了虽然两种算法与传统最佳中继选择(Best Relay Selection,BRS)算法分集增益相同但是可以取得最高为3dB的信噪比增益的结论,并进行了仿真验证。其次,针对单中继系统,本文提出了缓冲辅助的多用户中继链路选择技术。因为实际情况中,一个中继一般需要服务多个用户,这使得针对多用户中继传输技术的研究显得格外有意义。缓冲辅助的多用户中继系统可以根据信道状况的好坏自适应地选择当前时隙是中继接收信息还是中继转发信息,如果是中继接收信息,中继选择哪一条链路来接收信息。具体地在缓冲空间无限大的情况下以中继处缓冲收发数据平衡为限制条件,以系统和速率最大化为目标,运用KKT条件求得基于和速率的最优链路选择算法,并提出了形式与之类似的次优链路选择算法。在缓冲空间有限大的情况下,也提出了对应的链路选择算法。最后通过仿真分析了不同链路选择算法的吞吐量以及缓冲空间为有限大的情况下的系统时延。接着,在已提出的缓冲辅助的多用户中继系统链路选择技术的基础上,通过对次优链路选择技术的中断事件的分析,推导了中断概率上界的表达式,以及固定速率下满足缓冲收发平衡的门限值计算公式。证明了缓冲辅助的多用户中继系统相比于传统的多用户中继系统取得了明显的分集增益,并通过仿真验证了上述结论。
[Abstract]:Relay technology has become an important technology in the current and future mobile communication systems. The traditional semi duplex relay transmission technology is based on the alternating current mode in the previous slot of the relay, but the traditional relay transmission mode is greatly affected by the channel condition, that is, it is followed by two links. When the channel condition of any link is poor, the fixed transmission mode in the relay will make the system difficult to achieve more ideal performance. The buffer assisted relay transmission technology, that is, gives the relay a certain storage and buffer space, so that the relay can not follow a fixed transmission mode, but let relay the relay. It has more freedom while receiving and sending information. The system can adaptively select link transmission information according to the condition of different link channels in the same time slot and a certain selection algorithm. Buffer auxiliary relay technology is proposed, which breaks the original curing relay transmission mechanism and opens up the research of relay transmission technology. This paper mainly studies the buffer assisted relay transmission technology. The buffer assisted relay transmission technology has two main applications based on the number of relay nodes, that is, the relay selection technique under the multi relay node model and the chain path selection technique under the single relay node model. A relay selection technique for buffer assistance is given, that is, a relay selected to receive information can store information in a buffer until the next time it is selected for sending information. It can make the system always select the best source to relay link to transmit information at the previous time slot and choose the best in the latter time slot. The optimal relay selection (Max-Max Relay Selection, MMRS) algorithm for infinite buffer space is given. A hybrid relay selection (Hybrid Relay Selection) algorithm is given for the limited buffer space. The two algorithms and the traditional optimal relay selection are obtained by deducing the broken probability. The Best Relay Selection (BRS) algorithm has the same diversity gain but can obtain the maximum signal to noise ratio gain of 3dB, and the simulation verification is carried out. Secondly, this paper proposes a buffer assisted multi user relay link selection technique for the single relay system. In the actual situation, a relay usually needs to serve multiple users, It makes it very meaningful to study the multi user relay transmission technology. The buffer assisted multi user relay system can adaptively select the current slot as the relay receiving information or relay forwarding information according to the channel condition. If the relay receives information, the relay selects which link to receive information. Under the condition that the buffer space is infinitely large, the optimal link selection algorithm based on and rate is obtained by using KKT conditions to maximize the system and rate, and a suboptimal link selection algorithm, which is similar to it, is proposed. In the end, the throughput of the different link selection algorithms and the system delay in the case of limited buffer space are analyzed by simulation. Then, on the basis of the proposed buffer assisted multi user relay system link selection technology, the analysis of the interruption events of the suboptimal chain route selection technique is derived. The expression of the upper bound of the interruption probability and the threshold value calculation formula which satisfies the buffer balance at the fixed rate prove that the buffer auxiliary multiuser relay system has obtained a distinct diversity gain compared to the traditional multiuser relay system, and the above conclusion is verified by simulation.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

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