高能效协作组播中资源分配方法的研究

发布时间：2018-07-05 02:15

本文选题：无线组播 + 双时隙　；参考：《电子科技大学》2014年硕士论文

【摘要】：无线组播技术可以在同一频段向不同用户同时发送相同数据,从而大大提高频谱效率并增加系统容量。近年来,对于无线组播及其相关技术的研究越发热门。尤其是在状态控制、时钟同步以及诸如IPTV、视频会议这些新兴业务中,无线组播的高效可靠为它们提供了强大的技术支持。由于传统组播时通常采用信道状态信息(Channel State Information,CSI)最差用户的可达速率进行数据传输,这虽然可以保证组播成功率,但是传输速率较低,尤其是随着用户数量的增加,组播速率可能趋于极低值,组播系统的容量也相应急剧降低;而另一种方法则是采用预设的固定速率进行传输,但可能导致中断概率较高,不能满足系统的成功率要求,导致整个组播无法获得预期的容量增益。采用协作通信的双时隙组播技术利用重传转发可以很好地克服上述缺点。该方法利用协作通信与数据重传技术,通过空间分集与时间分集获得复用增益,在提高系统容量的同时兼顾了用户公平性。然而,已有的双时隙协作组播大部分都是建立在时隙长度固定或者发射功率固定的基础上,随着绿色通信的日渐普及,以及无线组播系统对续航能力的要求的提高,提高无线组播通信的能量效率的相关研究也越发重要,中继功率可变与时隙可变的组播方案研究在这方面有着重要意义。本文从协作组播模型出发,针对基于终端到终端(Device-to-Device,D2D)技术的双时隙组播模型下的资源分配问题,展开了以下研究工作:首先,分析了协作组播技术中的双时隙重传组播系统模型,总结归纳了典型的双时隙协作组播方法,并给出了简单的性能分析与比较。其次,在中继功率动态可变的基础上,提出了一种基于信道增益的功率分配方案。首先在双时隙组播的基础上构建了功率可变的中继模型,然后通过半定松弛进行约束放缩,转化为凸优化问题,进而求解得到了相应的功率分配方案。最后,从降低接收复杂度的角度,对用户接收信号的合并方式进行了简化改进,并研究了合并路数对性能的影响。再次,从时隙可变的角度出发,研究了双时隙组播模型下的时隙因素对于无线组播能效的影响。将时隙因素与功率控制结合起来,研究了不同时隙分配方案下组播系统的能量效率,针对集中式系统与分布式场景下的组播系统分别进行了分析与仿真,结果显示与传统固定时隙方案相比获得了显著的性能提升。
[Abstract]:Wireless multicast technology can simultaneously transmit the same data to different users in the same frequency band, thus greatly improving the spectral efficiency and increasing the system capacity. In recent years, the research on wireless multicast and its related technologies has become more and more popular. Especially in state control, clock synchronization and emerging services such as IPTV and video conferencing, the high efficiency and reliability of wireless multicast provide powerful technical support for them. In traditional multicast, the data transmission rate of the worst users of Channel State Information (CSI) is usually used for data transmission, which can guarantee the success rate of multicast, but the transmission rate is low, especially with the increase of the number of users. The multicast rate may tend to be extremely low and the capacity of the multicast system will decrease rapidly. Another method is to adopt a fixed rate of transmission, but it may lead to a high probability of interruption, which can not meet the requirements of the system's success rate. As a result, the entire multicast can not achieve the desired capacity gain. The double time slot multicast technology for cooperative communication can overcome these shortcomings well by retransmission and forwarding. The method uses cooperative communication and data retransmission techniques to gain multiplexing gains through spatial diversity and time diversity, which improves system capacity and takes account of user fairness. However, most of the existing double time slot cooperative broadcasts are based on fixed slot length or transmission power. With the increasing popularity of green communication and the improvement of the requirement of the wireless multicast system, The research on improving the energy efficiency of wireless multicast communication is becoming more and more important. The research of multicast schemes with variable relay power and time slot is of great significance in this respect. Based on the cooperative group broadcasting model, this paper focuses on the resource allocation in the dual-slot multicast model based on the Device-to-device D2D technology. The following research works are carried out: firstly, the model of the dual-slot retransmission multicast system in the cooperative group broadcasting technology is analyzed. In this paper, the typical double time slot cooperative broadcasting methods are summarized, and simple performance analysis and comparison are given. Secondly, a power allocation scheme based on channel gain is proposed based on the dynamic variation of relay power. Firstly, a relay model with variable power is constructed on the basis of double time slot multicast, then the constraint scaling is done through semidefinite relaxation, which is transformed into a convex optimization problem, and the corresponding power allocation scheme is obtained. Finally, from the point of view of reducing the reception complexity, the merging mode of the received signals is simplified and improved, and the effect of the number of the merging paths on the performance is studied. Thirdly, from the point of view of time-slot variable, the effects of slot factors on wireless multicast energy efficiency under the dual-slot multicast model are studied. Combining slot factor with power control, the energy efficiency of multicast system under different slot allocation schemes is studied. The analysis and simulation of multicast system under centralized system and distributed scenario are carried out. The results show that compared with the traditional fixed time slot scheme, the performance is improved significantly.
【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】：TN92

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