Laser Radio: Backhaul Solution for 5G Networks

Free space laser communications provides wide bandwidth and high security capabilities to cellular backhaul network in order to successfully accomplish data communication between cell sites and NOC (Network Operation Center). For this application, an optical receiver is a critical component and needs to be designed to operate in sunlight and other ambient noise environments while providing reliable data transmission. In this paper, a method of Free Space Laser Communication along with a differential optical receiver is presented for the backhaul solution of 5G networks that provides high capacity, reliability, less deployment cost, and long distance reach. At the receiver, two photo diodes are cross coupled. The effect is that the net output power is close to zero. The laser signal is then transmitted only into one of the receivers. With all other signals being cancelled out, the laser signal is an overwhelmingly dominant signal. In the proposed configuration, two signals generating photo-receptors are arranged such that when they are opposed to one another, the effect is a cancellation, if and only if the both photo-receptors receive the same amount of input.