Cognitive Co-Existence of Unlicensed Wireless Networks through Beamforming

Wireless fidelity (Wi-Fi) has become a key access technology, which offloads significant percentage of mobile Internet traffic. Nevertheless, QoS provisioning over dense WiFi faces many challenges due to the nature of its contention-based protocol and poor inter-network coordination. In light of this, long-term evolution (LTE) technology, which benefits from centralized coordination, has been proposed to exploit unlicensed spectrum through LTE-U for data offloading. However, the prosperity of deploying LTE in very crowded unlicensed band relies on the effective coexistence among LTE-U and increasingly dense Wi-Fi networks. In this paper, we propose to use the space dimension and beamforming to facilitate the effective coexistence and inter-network coordination. Two distinct approaches to evaluate the proposed coexistence mechanism, namely, Wi-Fi received power minimization and LTE user signal to noise ratio (SNR) maximization, have been investigated. The two proposed algorithms are simulated to show the potential and effective feasibility of coexistence between Wi-Fi and LTE in unlicensed spectrum.