OFDMA Downlink Resource Allocation in User-Deployed Femtocells

移动的运营商以成本有效的方式改善覆盖并提供高数据速率服务的一个选项是新兴的毫微微蜂窝网络，其中，低功率毫微微蜂窝接入点（FAP）覆盖在宏/微蜂窝网络上，每个接入点都能够向短距离内的用户提供高数据速率无线连接。毫微微小区的室内部署可以解决建筑物内的弱宏小区信号的问题，并且从宏小区卸载大量的业务，从而导致利用单个无线电接入技术（诸如正交频分多址（OFDMA），其已经被下一代无线网络的主要候选技术在下行链路中考虑）的无处不在的室内/室外覆盖的有前景的解决方案。OFDMA与毫微微蜂窝基站的结合被广泛期望为无线网络的覆盖和容量提供巨大的改进。小区间干扰管理是运营商在广泛部署毫微微蜂窝基站之前必须面对的最紧迫的挑战之一。作为即插即用设备，大多数FAP将由最终用户部署，并且可以随时移动或打开/关闭。运营商根本不知道活跃的FAP的数量和位置。因此，毫微微小区中的小区间干扰不能使用传统的网络规划方法来管理。FAP必须能够以最小的干扰将其自身集成到蜂窝网络中。关于毫微微小区部署中的干扰避免的大多数现有工作是针对宽带码分多址（WCDMA）网络的，而对于基于OFDMA的毫微微小区几乎没有进行工作，其中可以从跨不同小区的OFDMA无线电资源的时间和频谱重用的角度来实现干扰避免。本项目的目的是开发解决方案，通过OFDMA下行链路资源分配在一个网络中的毫微微蜂窝覆盖在宏蜂窝小区间干扰避免。我们的工作将集中在以下两个任务上：a）开发基于毫微微小区之间的OFDMA无线电资源的部分时间和频谱重用的低复杂度干扰避免解决方案，以及B）开发用于OFDMA下行链路的动态时间-频率资源分配算法，以提供小区间干扰避免并实现跨网络的宏小区和毫微微小区的频率重用因子1。这些前沿话题涵盖了未来无线网络的一些关键方面，并可能为实现无处不在的室内/室外覆盖奠定基础。

One option for mobile operators to improve coverage and provide high-data-rate services in a cost-effective way is the emerging femtocell network, where low-power femtocell access points (FAPs), each being able to provide high-data-rate wireless connections to users within a short range, are overlaid on macro/micro cellular networks. Indoor deployments of femtocells can solve the problem of weak macrocell signal inside a building and offload a large amount of traffic from macrocells, leading to a promising solution for ubiquitous indoor/outdoor coverage with a single radio-access technology, such as the orthogonal frequency division multiple access (OFDMA) that has been considered in the downlink by major candidate technologies for next generation wireless networks. OFDMA combined with femtocells is widely expected to deliver massive improvements of coverage and capacity for wireless networks. Inter-cell interference management is among the most urgent challenges that operators must face before femtocells can be widely deployed. As plug-and-play devices, most FAPs will be deployed by end users and could be moved or switched on/off at any time. The number and locations of active FAPs are by no means known to operators. Therefore, inter-cell interference in femtocells cannot be managed using conventional network planning methods. An FAP has to be able to integrate itself into the cellular network with least interference caused. Most existing work on interference avoidance in femtocell deployments is for wideband code division multiple access (WCDMA) networks, while little work has been done for OFDMA-based femtocells, where interference avoidance can be implemented from a perspective of temporal and spectral reuse of OFDMA radio resources across different cells. This project aims to develop solutions for inter-cell interference avoidance through OFDMA downlink resource allocation in a network that has femtocells overlaid on macrocells. We will focus our work on the following two tasks: a) the development of a low-complexity interference-avoidance solution based on partial temporal and spectral reuse of OFDMA radio resources between femtocells, and b) the development of a dynamic time-frequency resource allocation algorithm for the OFDMA downlink to provide inter-cell interference avoidance and achieve a frequency reuse factor of 1 across macro and femto cells of the network. These cutting-edge topics cover some of the key aspects of future wireless networks and may lay the foundation to attain ubiquitous indoor/outdoor coverage.