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Seminar Announcement 9:00 a.m. ~ 12:00 a.m., January 19, 2017, Room: 107, GREAT Title: High Energy-Efficient Cooperative Channels Allocation in Unlicensed Spectrum for D2D Assisted Cellular Networks Dr. Taras Maksymyuk and Prof. Minho Jo Abstract Recent interesting activities in spectrum analysis have suggested an additional band 5 GHz unlicensed spectrum for LTE networks. 5 GHz unlicensed spectrum has been used for Wi-Fi. The new paradigm, known as LTE-Unlicensed (LTE-U: LAA and LWA), has shown a great potential to boost the capacity of 5G 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, which gives negative impact on the spectral and energy efficiency. In this work, we have developed a new approach for cooperative LTE-U/LBT for the case of D2D (Device to Device) 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. The cluster devices sense the carrier occupancy alternately and share the obtained information with other cluster members. Thus, the number of sensing attempts will decrease 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 accesses to the unlicensed channel. It means that if one cluster member wins the contention for the channel, other members will be the next winners for this channel according to the queue and without additional contest. Our proposed scheme allows to improve the energy efficiency as well as to increa