Future 5G cellular networks are facing the challenging task on increasing their capacity dramatically. Despite some cutting-edge capacity-approaching techniques, the limited licensed spectrum is still a major bottleneck for capacity improvement. To tackle this issue, a new standard has been developed within 3GPP for LTE systems, currently on the licensed bands, to operate on the unlicensed bands, which is called LTE on unlicensed bands (LTE-U). LTE has many advanced techniques, which can be exploited in the unlicensed bands to achieve a high spectral efficiency. However, the unlicensed bands are currently occupied by the widely-deployed WiFi networks. The major challenge on LTE-U is how to design fair and efficient coexistence mechanisms between LTE and WiFi networks. In this talk, we will first discuss traditional traffic offloading, resource sharing, and hybrid of the both for LTE users to optimally exploit unlicensed bands while guaranteeing of the QoS of the existing WiFi users. To improve both the LTE and WiFi users simultaneously and achieve a win-win situation, we then provide a novel traffic offloading strategy, which is just opposite to the traditional one and offloads some WiFi users to the LTE networks and at the same time relinquishes some unlicensed bands to LTE-U. Since the unlicensed bands are usually operated less energyefficiently than the licensed ones due to the higher carrier frequency of the unlicensed bands and larger path loss, we also present a framework for energy-efficiency (EE) optimization in LTE-U. We establish a criterion to determine whether the EE of the LTE system can be improved with the help of the unlicensed bands. Based on the criterion, we then develop a joint licensed and unlicensed resource allocation algorithm to maximize the EE of each LTE small cell base station.

Location:
Room: ICR 1304
Bldg: Davis Centre
University of Waterloo
200 University Avenue West
Waterloo, Ontario
N2L 3G1