Hidden Node Aware Resource Allocation in Licensed-Assisted Access Systems

Licensed-assisted access (LAA) adds great value to cellular networks by extending access to the unlicensed bands, which leads to increased capacity and spectrum efficiency. To fully take advantage of LAA systems and achieve fair coexistence with Wi-Fi networks, channel access mechanisms, such as the listen before talk (LBT), are required. However, due to the LBT mechanism, LAA systems may suffer from the interference of WiFi hidden nodes. In this paper, a hidden node aware joint licensed and unlicensed resource allocation algorithm for LAA systems is proposed. By utilizing measurable medium access control (MAC) layer statistics, an adaptive unlicensed band weight factor is introduced to reflect the impact of Wi-Fi hidden nodes. A resource allocation optimization problem is formulated to maximize the throughput of LAA with quality of service (QoS) guarantee, then an iteration-based solution is obtained by optimizing subcarriers and power allocation in the licensed band and fraction of time allocation in the unlicensed band with fixed power. Extensive simulation results are given to evaluate the performance and validate the effectiveness of the proposed algorithm.