Energy Efficient Scheduling for Delay-Constrained Spectrum Aggregation: A Differentiated Water-Filling Approach

Spectrum aggregation (SA) enables wireless devices to utilize heterogeneous resources, which can potentially fulfill the requirement of broadband services. In this paper, we study the delay-constrained SA, where the characteristics of SA bring various technical challenges. Specifically, the SA capability limitation induces a complicated coupling among the data rate, power and channel allocation, and the total power consumption varies according to the channel aggregation due to the SA circuit structure. Moreover, with these practical considerations, the water-filling power allocation cannot be adopted over all the channels. To overcome these challenges, we design the efficient scheduling for delay-constrained SA (ESSA) scheduling scheme in two steps. First, given the sum data rate and the channel allocation, we minimize the total power consumption for SA, including both the transmit power and the circuit power. Due to the properties of delay-constrained SA, we divide the scheduled users into conforming and nonconforming user sets, and design their water-filling power allocation strategies differentially. Second, based on the differentiated water-filling power control, we optimize the channel allocation and rate control iteratively via Lyapunov optimization to minimize the power consumption under average delay constraint. The proposed ESSA scheme is finally evaluated by simulation.