无线多跳中继网络资源分配与调度策略研究

发布时间：2018-05-19 07:32

本文选题：无线资源管理 + 正交频分复用　；参考：《西南交通大学》2014年博士论文

【摘要】：正交频分复用(OFDM)/正交频分复用多址(OFDMA)和中继(Relay)技术相结合的多跳中继网络由于具有高频谱效率、增强覆盖、组网灵活,布网成本低等众多优点,已成为业界公认的下一代无线网络的主流架构。与传统蜂窝网络相比,基于OFDM/OFDMA技术的中继网络面对的环境更加复杂,使得无线资源管理问题变得更具挑战性：一方面,资源分配的维度由传统的时域、频域或空域向多维空间联合分配的方向发展,传统的资源分配策略无法直接应用到中继网络,且造成资源分配的算法复杂度和系统的信令开销增大；另一方面,无线数据业务的快速增长和大量低功率中继站点的引入使得系统功率消耗大大增加,基站能耗占所有设备能耗的一半以上,然而,过去大部分研究都是关注如何提高系统的吞吐率。随着近年“绿色通信”的提出,如何在保证用户服务质量(QoS)前提下,提高系统的能效,进而达到节能的目的,业已成为当前无线通信技术发展新的趋势。为此,本文以基于OFDM/OFDMA技术的无线多跳中继网络为研究对象,以系统节能为主要目标,研究路径选择、分组调度和资源分配等无线资源管理关键技术。首先,针对放大转发(AF)和解码转发(DF)的OFDM中继系统,分别提出一种能效最大化路径选择策略。针对三节点中继OFDM网络,在分析电路功率消耗、用户速率需求、带宽等因素在路径选择时对系统能效的影响基础上,通过将中继链路衰落值和直传链路衰落值转化为等效路径损耗值,分别提出一种基于等效路径损耗指数的能效最优路径选择准则。分析结果表明,能效最优传输路径取决于用户速率需求、链路信道条件以及系统带宽等因素,并满足本文所提出的能效最优路径判决准则。在此基础上,将三节点DF中继传输场景扩展到多用户多中继OFDMA蜂窝网下行传输系统,考虑电路功率消耗和固定用户速率需求的条件下,以能效最大化为目标,提出-种联合路径选择、子载波和功率分配的低复杂度次优算法。分析结果表明,与传统路径选择策略相比,所提路径选择方案能够显著提升系统能效。其次,针对三节点DF模式中继OFDM传输链路,提出一种系统总发射功率和用户最小速率需求受约束条件下子载波配对和功率分配的能效最优联合优化方案。该方案考虑了电路功率消耗对系统能效的影响,由于该问题属于非凸优化问题,直接求解复杂度高且难以实现,为此,提出一种分情况讨论求解策略,将非凸优化问题转化为凸优化问题求解,并证明了系统能效最优解的唯一性,再利用拉格朗日乘子法和KKT条件,通过注水算法获得系统能效最优解和功率分配结果。分析结果表明,与固定子载波配对能效最优功率分配策略相比,所提方案可以进一步提升链路可达速率和能效性能；与传统的速率最大化和功率最小化注水最优算法相比,所提方案可以根据系统总发射功率和用户速率需求约束条件自适应分配资源,以较低复杂度得到全局最优解,保证链路传输的可靠性。再次,考虑更为实际的源节点和中继节点发射功率各自约束条件,提出一种子载波配对和功率分配的联合优化方案。该方案针对三节点DF模式中继OFDM传输系统,同时考虑电路功率消耗和用户最小速率需求,以能效最大化为目标,建立联合子载波配对和功率分配的优化模型,采用分步求解策略,将非凸优化问题转化为凸优化问题,利用注水策略获得能效最优解。分析结果表明,所提方案能够在满足各项约束条件情况下自适应分配资源,达到系统能效最优,同时还可以保证链路传输可靠性,降低链路的中断概率和算法实现复杂度。接着,针对两跳中继OFDMA蜂窝网下行传输系统,提出一种自适应关联节能分组调度方案。该方案考虑不同类型业务QoS需求的差异性,用户分组队列状态,以及链路能效等综合因素设计调度优先级因子,在此基础上,基于透明中继传输场景,提出一种可以平衡接入域和透明域资源占用的比例的自适应分组调度策略,减少由于接入域和透明域的剩余资源比例失调而导致的中继用户分组数据无法及时调度的问题,进而提高系统时隙资源的利用率。分析结果表明,该方案能满足不同类型业务QoS需求,保证用户间的公平性；在保证系统吞吐量性能基础上,进一步降低系统能耗。最后,针对两跳中继OFDMA蜂窝网下行传输系统,提出一种半分布式自适应分组调度方案。该方案能够区分实时(RT)和非实时(NRT)业务的QoS需求。为了保证实时业务的QoS需求和非实时业务获得一定的受调度机会,该方案给出一种能区分业务类型的改进的比例公平分组调度优先级因子设计方案；为了降低中继传输系统的信令开销,设计了一种自适应时隙重分配触发机制,将BS和RS端定义的满意度因子与给定的满意度阈值进行比较,以决定是否触发时隙重分配过程。一旦触发时隙重分配,BS端调度器将根据BS端和各个RS端请求时隙数自适应调整BS和各个RS间的带宽分配比例。分析结果表明,所提半分布式分组调度策略一方面可以提高系统吞吐量,满足用户的QoS需求,保证用户间公平性,另一方面可以降低系统的信令开销,有效降低中继用户切换丢包率。
[Abstract]:Orthogonal frequency division multiplexing (OFDM) / orthogonal frequency division multiplexing (OFDMA) and relay (Relay) multi hop relay networks have many advantages, such as high frequency spectrum efficiency, enhanced coverage, flexible networking and low network cost, which have become the mainstream architecture of the next generation of wireless networks recognized by the industry. Compared with traditional cellular networks, OFDM/OFDMA The environment of the relay network is more complex, which makes the problem of wireless resource management more challenging: on the one hand, the dimension of resource allocation is developed from the traditional time domain, frequency domain or space to multi-dimensional space. The traditional resource allocation strategy can not be directly applied to the relay network, and the allocation of resources is calculated. On the other hand, the rapid growth of wireless data services and the introduction of a large number of low power relay stations make the power consumption of the system greatly increased, and the energy consumption of the base station accounts for more than half of the energy consumption of all devices. However, most of the past studies are concerned about how to improve the throughput of the system. "Green communication" puts forward how to improve the energy efficiency of the system and achieve energy saving on the premise of guaranteeing the quality of user service (QoS), and it has become a new trend in the development of current wireless communication technology. Therefore, this paper takes the wireless multi hop relay network based on OFDM/OFDMA Technology as the research object, and studies the system energy saving as the main goal. The key technologies of wireless resource management are path selection, packet scheduling and resource allocation. Firstly, a path selection strategy for maximum energy efficiency is proposed for the OFDM relay system of amplified and forward (AF) and decode and forward (DF). For the three node relay OFDM network, the power consumption, user rate demand, bandwidth and other factors are analyzed in the path. On the basis of the influence of the selection on the energy efficiency of the system, the optimal path selection criterion based on the equivalent path loss index is proposed by converting the fading value of the relay link and the direct link fading value into the equivalent path loss value. The results show that the optimal transmission path of the energy efficiency depends on the user rate demand and link channel condition. On this basis, the three node DF relay transmission scene is extended to a multiuser and multi relay OFDMA cellular network downlink transmission system. Considering the power consumption of the circuit and the fixed user rate requirement, the energy efficiency maximization is taken as the goal, and the proposed approach is proposed. The analysis results show that the proposed path selection scheme can significantly improve the system energy efficiency compared with the traditional path selection strategy. Secondly, a constraint on the total transmission power and the minimum user rate requirement is proposed for the three node DF mode relay OFDM transmission link. This scheme considers the effect of power consumption on the energy efficiency of the system, which considers the effect of power consumption on the energy efficiency of the system. Because this problem belongs to the non convex optimization problem, it is difficult to solve the problem directly and it is difficult to realize. Therefore, a method of solving the problem is proposed and the non convex optimization problem is transformed into a convex optimization problem. The problem is solved, and the uniqueness of the system energy efficiency optimal solution is proved. By using the Lagrange multiplier method and the KKT condition, the system energy efficiency optimal solution and power allocation result are obtained by water injection algorithm. The analysis results show that the proposed scheme can further improve the link accessibility compared with the fixed sub carrier pairing energy efficiency optimal power allocation strategy. Rate and energy efficiency performance; compared with the traditional optimal rate maximization and power minimization injection optimization algorithm, the proposed scheme can allocate resources adaptively according to the system total transmission power and user rate requirements constraints, obtain the global optimal solution with lower complexity and ensure the reliability of link transmission. Again, consider more practical source nodes. A joint optimization scheme for seed carrier pairing and power allocation is proposed in this scheme. The scheme aims at the three node DF mode relay OFDM transmission system, taking into account the power consumption of the circuit and the minimum user rate requirement, aiming at maximizing the energy efficiency, and establishing the joint subcarrier pairing and power allocation. The optimization model, using the step solving strategy, transforms the non convex optimization problem into a convex optimization problem, and uses the water injection strategy to obtain the energy efficiency optimal solution. The analysis results show that the proposed scheme can allocate resources adaptively to meet the constraints of various conditions and achieve the optimal energy efficiency of the system. At the same time, the link transmission reliability can be guaranteed and the link can be reduced. The probability of interruption and the complexity of the algorithm are realized. Then, an adaptive association energy saving packet scheduling scheme is proposed for the downlink transmission system of two hop relay OFDMA cellular networks. This scheme takes into account the difference of QoS requirements of different types of services, the state of the packet queues, and the link energy efficiency to design the scheduling priority factors. Based on the transparent relay transmission scene, an adaptive packet scheduling strategy is proposed to balance the proportion of the resource occupancy of the access domain and the transparent domain, which reduces the delay of the packet data of the relay users due to the imbalance of the remaining resources in the access domain and the transparent domain, and thus improves the profit of the system time slot resources. The analysis results show that the scheme can meet the QoS requirements of different types of services and ensure fairness among users. On the basis of guaranteeing system throughput performance, the system energy consumption is further reduced. Finally, a semi distributed adaptive packet scheduling scheme is proposed for the downlink transmission system of two hop relay OFDMA cellular networks. QoS requirements for real-time (RT) and non real time (NRT) services. In order to ensure that the QoS requirements and non real time services of real time services are given a certain number of scheduling opportunities, the proposed scheme provides an improved proportional fair packet scheduling priority factor design scheme that distinguishes the service types from the traffic type, and designs the signaling overhead for reducing the relay transmission system. An adaptive time slot redistribution trigger is used to compare the satisfaction factor defined by the BS and the RS side with a given satisfaction threshold to determine whether to trigger the time slot redistribution process. Once the time slot redistribution is triggered, the BS end scheduler adaptively adjusts the bandwidth allocation ratio between the BS and each RS based on the BS end and each RS end request time slot number. The analysis results show that the proposed semi distributed packet scheduling strategy can improve the system throughput, meet the user's QoS requirements and ensure fairness among users. On the other hand, it can reduce the signaling overhead of the system and effectively reduce the packet loss rate of the relay users.
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN929.5

【参考文献】