  LTE/WiFi Aggregation (LWA) provides a promising approach to relieve data
traffic congestion in licensed bands by leveraging unlicensed bands. Critical
challenges arise from provisioning quality-of-service (QoS) through
heterogenous interfaces of licensed and unlicensed bands. In this paper, we
minimize the required licensed spectrum without degrading the QoS in the
presence of multiple users. Specifically, the aggregated effective capacity of
LWA is firstly derived by developing a new semi-Markov model. Multi-band
resource allocation with the QoS guarantee between the licensed and unlicensed
bands is formulated to minimize the licensed bandwidth, convexified by
exploiting Block Coordinate Descent (BCD) and difference of two convex
functions (DC) programming, and solved efficiently with a new iterative
algorithm. Simulation results demonstrate significant performance gain of the
proposed approach over heuristic alternatives.
