A MAC solution for distributed coordination of 5G LAA operator networks and fair coexistence with WLAN in unlicensed spectrum

Acquiring more spectral resources is a key enabler for the envisioned high data rates of next generation mobile networks. Licensed-assisted access (LAA) to the vast and free-of-charge unlicensed spectrum has been therefore receiving tremendous interest, especially with the advancements in small cells and carrier aggregation. We propose a novel 5G MAC solution for fair and efficient coexistence with WLAN and other 5G operator networks in unlicensed spectrum (5G-U). A UE-centric joint association and channel selection algorithm maximizes the achievable long-term rates. Neighboring LPNs of the same 5G-U network opportunistically form per-channel disjoint radio access clusters (RACs). During an active sensing phase, RACs discover their potential interferers and `contend-to-coordinate' their self-allocation of the unlicensed channel. A self-allocated RAC dynamically optimizes its coexistence frames with WLAN to achieve the estimated soft airtime share over the coordination frame. We generalize the simple sequential inhibition model, which has been shown to accurately model the carrier sense multiple access, to capture the impact of longer LAA bursts as well as the priority access mode in the downlink simulations. Results with single-LPN RACs show substantial coexistence throughput gains compared to two different models of LTE-LAA. Additional gains are realized with multi-LPN RACs in dense deployment and high channel occupancy scenarios.