The intense demands for higher data rates and ubiquitous network coverage have raised the stakes on developing new network topology and architecture to meet these ever-increasing demands in a cost-effective manner. The telecommunication industry and international standardization bodies have placed considerable attention to the deployment of extremely dense networks, referred to as DenseNets, which creates a bundle of opportunities for high spatial reuse and energy efficiency by reducing the distance between Access Points (APs) and clients. Industrial practices of DenseNets include small-scale femtocells in LTE/LTE-A based cellular systems and WiFi hotspots in public places in IEEE 802.11 based High Efficiency WLAN (HEW). Both empirical experiences and theoretical analyses sugges...[ Read more ]

The intense demands for higher data rates and ubiquitous network coverage have raised the stakes on developing new network topology and architecture to meet these ever-increasing demands in a cost-effective manner. The telecommunication industry and international standardization bodies have placed considerable attention to the deployment of extremely dense networks, referred to as DenseNets, which creates a bundle of opportunities for high spatial reuse and energy efficiency by reducing the distance between Access Points (APs) and clients. Industrial practices of DenseNets include small-scale femtocells in LTE/LTE-A based cellular systems and WiFi hotspots in public places in IEEE 802.11 based High Efficiency WLAN (HEW). Both empirical experiences and theoretical analyses suggest that DenseNets will encompass significant technical challenges related to reliable and efficient access and management. On the one hand, DenseNets contain a significant number of densely-deployed APs with highly overlapped regions, making network maintenance a complicated and challenging task. On the other hand, there are normally a crowd of clients in DenseNets, and thus efficient access control is expected to meet the high per-user-throughput demands with a limited amount of bandwidth.

We have two proposals for DenseNets, where each aims to address one challenge as mentioned above. First, we propose an automatic fault management framework for dense femtocell networks. Under this framework, we propose three system designs for outage detection, fault diagnosis, and self-healing functions. As the first step of our automatic management framework, the proposed outage detection design exploits signal correlations among multiple femtocells to improve detection accuracy for small-size densely-deployed femtocell networks. The outage detection system triggers fault diagnostic system. In our diagnostic system design, we develop a transfer learning based approach to overcome the data scarcity issue in small-size femtocells. After identifying the specific fault, outage is compensated by a self-healing scheme. We study the interference outage case, and propose a local cooperative grouping architecture to iteratively recover the network outage. Second, we propose an efficient access framework for WiFi networks with large audience environments. We analyze the poor performance of WiFi for large audience environments, and propose a PHY/MAC design to improve efficiency in public WLANs. The proposed design aggregates multi-user’s transmissions into one transmission so as to reduce contention overhead. The above studies demonstrate that with appropriate system designs, reliable and efficient DenseNets can be achieved to meet high data rate and ubiquitous connection demands.