OFDMA Downlink Resource Allocation in User-Deployed Femtocells

移动运营商以经济高效的方式改善覆盖和提供高数据速率服务的一种选择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，每个接入点都能够为短距离内的用户提供高数据速率无线连接。在室内部署毫微微蜂窝可以解决建筑物内宏蜂窝信号微弱的问题，并从宏蜂窝中分流大量流量，从而通过单一的无线电接入技术为无处不在的室内/室外覆盖提供了一种有前途的解决方案，例如下一代无线网络的主要候选技术已经考虑在下行链路中使用的正交频分多址(OFDMA)。人们普遍预计，OFDMA与毫微微蜂窝的结合将极大地改善无线网络的覆盖范围和容量。小区间干扰管理是运营商在广泛部署毫微微小区之前必须面临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，并可以随时移动或打开/关闭。运营商决不知道现役FAP的数量和位置。因此，不能使用传统的网络规划方法来管理毫微微小区中的小区间干扰。FAP必须能够以最小的干扰将自己整合到蜂窝网络中。大多数现有的关于毫微微小区部署中的干扰避免的工作是针对宽带码分多址(WCDMA)网络的，而对于基于OFDMA的毫微微小区的工作很少，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。该项目旨在通过OFDMA下行链路资源分配在覆盖在宏小区上的毫微微小区的网络中开发小区间干扰避免的解决方案。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OFDMA无线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下行链路的动态时频资源分配算法，以提供小区间干扰避免，并在网络的宏小区和毫微微小区之间实现1的频率重用因子。这些前沿主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.