【作者】 李立英；

【导师】 徐红兵；

【作者基本信息】 电子科技大学 ， 检测技术与自动化装置， 2011， 博士

【摘要】 随着现在通信技术和社会科技的飞速发展,人们对于通信质量的要求越来越高。通信质量通常是由通信带宽、发射功率、编码调制方式、信道质量和通信环境决定的。在一个通信系统中如何给用户分配这些资源,包括带宽、发射功率、编码调制方式等,使得系统的数据传送率最大、服务质量最好成为现在通信研究的热门和关键部分。另一方面,通信电池设备的发展缓慢和现在生态环境的需求,如何在保证通信质量的情况,降低通信能量的消耗,达到能量有效的绿色通信,也是现在通信的关键问题。本文将从能量有效和频谱有效的角度去研究不同网络系统的资源分配和功率控制。认知无线电技术的提出为了解决频谱资源使用不合理,从而提高频谱资源的利用率。它可以让认知用户在授权用户不使用频谱的时候,接入并使用频谱资源。本文将研究认知用户如何感知信道并且决定最优的传送时间和功率分配。在做优化时,本文考虑了能量有效性、吞吐量(传送速率)、和对授权用户的干扰。本文证明了在使用多个信道进行数据传送时,存在一个最优闭式解,并且给出了在每个信道上的最优功率分配方案。协作网络技术是通过中继节点帮助源节点的通信来增加数据传送率,将协作网络技术应用于认知网络可以有效的提高认知用户系统的传送速率。本文在考虑频谱有效性的资源分配的同时,提出了一种在协作认知网络中中继节点选择和功率分配的最优方案,并且进一步提出一种简化的节点选择的次优方案。从仿真结果可以看出次优方案具有与最优方案相近的性能。在蜂窝通信系统中,小区间的干扰是影响系统性能的主要因素,特别是小区频率复用因子为1的系统。LTE作为下一代高速无线宽带网络技术,对通信资源、调制编码方式、和功率分配等给出了一系列的限制条件。本文将研究在LTE通信系统中的资源分配,针对LTE上行系统的频谱资源和功率分配,提出了一种当小区频率复用因子为1时基于小区之间信息交互的资源分配方式来降低小区之间的干扰,从而提高小区边缘用户的频谱效率和小区用户的平均频谱效率。同时,本论文对LTE下行系统进行频谱有效和能量有效的资源分配进行了研究,研究表明采用能量有效的资源分配不仅能够保证系统的数据传送率,而且也降低了小区之间的干扰。更多还原

【Abstract】 With the quick development of wireless communication technology and sharp increase in its applications, Quality-of-Service (QoS) in wireless systems is becoming very important. QoS of each user in a multiple access network depends on bandwidth, transmission power, coding and modulation, channel quality, etc. How to assign these resources to each user to optimize the throughput or QoS of the whole network is a critical issue for future wireless networks. On the other hand, the battery technology is unable to catch up with the sharply increasing capacity requirement in mobile devices. Consequently, energy-efficient wireless networks, also known as Green Radio, is becoming a more and more popular and critical research area, as evidenced by many workshops in international conferences, special issues of journals, and research groups in the world. Reducing energy consumption in wireless communications is also beneficial to environments and good for sustaining development. Therefore, this paper will focus on resource allocation for energy-efficient and spectral-efficient wireless networks in this dissertation.To effectively improve spectral efficiency of wireless networks, cognitive radio (CR) has been proposed to use the licensed spectrum when the licensed users are not active spatially or temporally. In this dissertation, how a CR user senses available spectrum bands, selects the most appropriate one, and then optimizes transmission parameters will be studied. When determining transmission period and power, this dissertation also takes spectral efficiency, throughput, and interference limit to the licensed users into consideration. The dissertation proves that there is a closed-form solution for the duration of data transmission. A power allocation method for all the used channels is also proposed in the dissertation.Cooperative relay technique can improve throughput and mitigate interference in wireless networks, which is an ideal technique for CR. This dissertation will apply this technique in CR networks to increase throughput of cognitive users and avoid interference to the licensed users. Since both relay node selection and power allocation relate to the spectral efficiency of CR networks, this dissertation first develops a joint relay selection and power allocation approach that maximizes the throughput of a CR network with cooperative relay. The dissertation then proposes a simplified approach that significantly reduces the complexity with only minor performance degradation. The simplified approach performs almost as well as the optimal method, which can be seen from the simulation results.In cellular networks, inter-cell interference (ICI) significantly degrades performance, especially for a network with a unit frequency reuse factor. Long term evolution (LTE) is a standard for future cellular networks. In the LTE standard, many practical constraints are posted on frequency resource, coding and modulation, power allocation, etc. In the dissertation, a resource allocation and power assignment scheme for uplink transmission under the above practical constraints is developed. The dissertation also studies energy-efficient resource and power allocation for downlink transmission in LTE. Our research indicates that the energy-efficient design not only maintains reasonable high throughput but also effectively mitigates ICI by reducing transmission power.更多还原