基于移动中继的端到端传输技术与性能研究

发布时间：2019-06-14 03:41

【摘要】：随着5G时代的到来,对高速移动互联网数据业务的需求越来越高。在营4G系统中提高小区吞吐量的方法在现有小区架构下已经达到性能极限,需要大力发展新型无线传输技术和网络架构。面向蜂窝移动通信系统的D2D通信技术应运而生,其通过复用蜂窝通信链路的时频资源以增加小区容量、提高资源利用率、降低能量消耗并获得高传输速率,近年来引起极大关注。在传统蜂窝网络中,中继技术可以增加功率利用率获得空间分集增益以对抗多径衰落。本论文将中继技术与D2D技术相结合,研究其中断概率以及遍历可达速率等系统性能。首先,研究了基于AF中继D2D通信系统的中断概率以及可达速率。考虑每个用户均受到干扰与噪声,分析推导了中断概率以及可达速率的闭合表达式。针对D2D链路的中断概率,讨论三种特殊场景包括：高SNR场景,D2D链路远离基站场景以及D2D链路远离蜂窝链路场景并推导了近似闭合表达式。在D2D链路总功率恒定的条件下,提出了D2D用户和中继用户间的功率分配方案以降低中断概率,得到了功率分配方案的解析表达式。对于系统可达速率,联合考虑了蜂窝链路与D2D链路的可达速率,在用户发射功率受限的前提下,提出蜂窝链路与D2D链路联合优化方案以最大化系统的可达速率,大大降低了算法复杂度。其次,在同时考虑节点所受干扰与噪声的场景下,提出了基于双向AF中继D2D传输模式,分析了D2D链路干扰模型,分别推导了强蜂窝用户干扰与弱蜂窝用户干扰两种场景下系统中断概率精确解表达式,并在此结果上进一步求出高SNR场景下的近似解。仿真结果验证推导的正确性并表明基于双向AF中继D2D通信系统的中断概率在不引入额外功率的前提下可以大幅提高系统的中断性能。随后,在同时考虑干扰及噪声的基于双向DF中继的D2D通信系统中,研究了D2D链路的中断概率以及遍历可达速率。根据基于双向DF中继系统的中断概率以及遍历可达速率的定义,讨论推导了在对称与非对称两种情况(中继用户从两D2D用户接收到的功率是否相等)下中断概率以及遍历可达速率的精确解析表达式。在精确表达式的基础上,得出了高SNR场景下的近似表达式。针对中断概率以及遍历可达速率两种系统性能,分别提出功率优化方案以最优化系统性能。接着,针对处于同一小区以及不同小区的两用户的传输模式,提出了模式切换策略以最大化可达速率。考虑两用户间的三种传输模式包括：传统蜂窝传输模式、D2D传输模式以及基于双向DF中继的D2D传输模式,提出了三种传输模式间的切换策略。结果显示当两用户距离很近时采用D2D传输模式而当两者距离很远时则采用传统蜂窝传输模式,当用户间距离介于中间值时采用基于双向DF中继的D2D传输模式性能最优。最后,研究了配置多天线的基站采用BF和IC预编码策略时D2D通信系统的遍历可达速率。推导了有限反馈MIMO系统以及基站可以获取理想CSI两种场景下,采用BF和IC策略时D2D系统的遍历可达速率的精确表达式以及上下界的表达式。基于这些结论,讨论了三种特殊场景包括高SNR场景、弱干扰场景以及大规模天线场景,分别推导了三种特殊场景下上下界的近似解。研究结果显示高信噪比场景以及弱干扰场景下系统的遍历可达速率存在稳定值,有限反馈MIMO系统中随着天线数增加系统的遍历可达速率同样存在一个稳定值,而对于理想CSI的场景系统的遍历可达速率随着天线数呈对数增长。
[Abstract]:With the arrival of the 5G time, the demand for high-speed mobile Internet data service is getting higher and higher. The method of improving the cell throughput in the 4G system of the camp has reached the performance limit under the existing cell architecture, and the new type of wireless transmission technology and the network architecture need to be vigorously developed. The D2D communication technology facing the cellular mobile communication system comes into being, which has caused great concern in recent years by multiplexing the time-frequency resources of the cellular communication link to increase the cell capacity, improve the resource utilization rate, reduce the energy consumption and obtain the high transmission rate. In a conventional cellular network, a relay technique can increase power utilization to obtain a spatial diversity gain to combat multi-path fading. In this paper, the relay technology and the D2D technology are combined to study the system performance such as the break probability and the traverse rate. First, the interrupt probability and the reachable rate of a D2D communication system based on the AF relay are studied. Considering that each user is subject to interference and noise, a closed expression of the interrupt probability and the reachable rate is derived. In view of the outage probability of the D2D link, the three special scenarios are discussed: the high SNR scene, the D2D link remote from the base station scene and the D2D link away from the cellular link scene and the approximate closed expression is derived. Under the condition that the total power of the D2D link is constant, the power distribution scheme between the D2D user and the relay user is proposed to reduce the interrupt probability and the analytic expression of the power distribution scheme is obtained. The reachable rate of the cellular link and the D2D link is considered in combination with the system reachable rate, and the joint optimization scheme of the cellular link and the D2D link is proposed under the premise of the limited user transmission power, so that the reachable rate of the system is maximized, and the algorithm complexity is greatly reduced. Secondly, under the scene of simultaneous consideration of the interference and noise of the node, a two-way AF relay D2D transmission mode is proposed, the D2D link interference model is analyzed, and the exact solution expression of the system interrupt probability under the two scenarios of strong cellular user interference and weak cellular user interference is derived respectively, And the approximate solution in the high SNR scene is further obtained on the result. The simulation result verifies the correctness of the derivation and indicates that the interruption probability based on the two-way AF relay D2D communication system can greatly improve the interrupt performance of the system without introducing additional power. Then, in the two-way DF-relay-based D2D communication system considering both the interference and the noise, the interrupt probability and the traverse rate of the D2D link are studied. Based on the interrupt probability of the two-way DF relay system and the definition of the traversal rate, the exact analytical expression of the interrupt probability and the traversal rate of the two cases (whether the relay user receives the power from the two D2D users) under the symmetric and asymmetric conditions (whether the power received from the two D2D users is equal) is discussed. On the basis of the exact expression, the approximate expression in the high SNR scene is obtained. In ord to optimize that performance of the system, a power optimization scheme is proposed to optimize the performance of the system. Then, for the transmission mode of two users in the same cell and different cells, a mode switching strategy is proposed to maximize the achievable rate. The three transmission modes between two users are considered: the traditional cellular transmission mode, the D2D transmission mode and the D2D transmission mode based on the two-way DF relay, and the switching strategy among the three transmission modes is proposed. The results show that when the distance between the two users is very close, the traditional cellular transmission mode is adopted, and when the distance between the users is between the intermediate value, the performance of the D2D transmission mode based on the two-way DF relay is optimal. Finally, the rate of traversal of the D2D communication system when the base station with multiple antennas is configured with the BF and the IC pre-coding strategy is studied. In this paper, a finite feedback MIMO system and a base station can be used to obtain the exact expression of the reachable rate of the D2D system and the expression of the upper and lower bounds when using the BF and the IC policy. Based on these conclusions, three special scenarios, including high SNR scene, weak interference scene and large-scale antenna scene, are discussed. The research results show that the high signal-to-noise ratio scene and the ergodic reach rate of the system under the low-interference scene are stable, and a stable value is also present in the limited feedback MIMO system with the increase of the number of antennas. While the traversal rate of the scene system for the ideal csi increases exponentially with the number of antennas.
【学位授予单位】：南京邮电大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN929.5

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