Delay-Aware LTE WLAN Aggregation in Heterogeneous Wireless Network

The scarcity of spectrum turns the next generation wireless network increasingly heterogeneous. Recently, much attention has been focused on exploiting the unlicensed spectrum to leverage traffic burden from the cellular network. Specified in 3GPP Release 13, long term evolution (LTE) wireless local area networks (WLAN) aggregation (LWA) promises an effective approach for the LTE WLAN interworking and unlicensed spectrum utilization. The LWA could improve the data rate by the licensed and unlicensed carriers aggregation. In contrast to the previous studies, where the LWA is always chosen to boost the peak data rate without considering the user payment, we jointly consider the LWA with Wi-Fi offloading in this paper, aiming to strike the balance between user payment and quality of service (QoS) requirement. We formulate the multi-slot modes selection as a finite-horizon Markov decision problem and propose a Delay-Aware LTE WLAN Aggregation (DLWA) algorithm to obtain the optimal transmission modes strategy. Due to the computational complexity of sequential decision problem, we exhibit the threshold structure of LTE usage and develop a low complexity algorithm based on this structure. Moreover, imperfection in LWA backhaul is considered and analyzed in this paper. Simulation results show the DLWA algorithm and threshold-based DLWA algorithm could guarantee the QoS requirement with lower user payment compared with current LTE WLAN interworking schemes.