Cooperative channels allocation in unlicensed spectrum for D2D assisted 5G cellular network

LTE-Unlicensed (LTE-U), has shown a great potential to boost the capacity of cellular networks. However, in most countries, implementation of LTE-U requires additional listen before talk (LBT) techniques to avoid interference between LTE-U and legacy Wi-Fi networks. Similar to conventional 802.11 protocol, LTE-U/LBT protocols perform quite well for the small number of users, whereas for the high number of users the bandwidth utilization decreases that has a negative impact on the spectral and energy efficiency. In this work, we develop a new approach for cooperative LTE-U/LBT for the case of D2D assisted cellular networks. The main idea is to reduce the number of total LBT attempts for each user by their cooperation within the D2D cluster. Each cluster is formed by two or more devices in the vicinity of each other, which sense the carrier occupancy alternately and share the obtained information with other cluster members. Thus, the number of sensing attempts is decreased proportionally to the number of users in a single cluster. To further improve the bandwidth utilization, cluster members configure the size of contention window to minimize the idle time between their access to the unlicensed channel. Simulation results show that proposed approach improves the energy efficiency and increases the overall capacity of LTE-U cellular network.