D2D broadcast communications for 4G PMR networks

As professional mobile radio (PMR) networks evolve to a new generation based on Long Term Evolution (LTE), a new direct communication mode needs to be developed. Not only in PMR networks, but the increase of proximity services due to the explosion of the internet of things bring us to a new communication paradigm. The PMR users have very specific requirements and one of those is the ability to communicate in a direct way with all the group members, even in out-of-coverage scenarios. In the current PMR standards, communication degradations due to collisions can occur when there is no infrastructure available, especially in dense scenarios. In this article, we propose a mechanism that allows device-to-device (D2D) broadcast communications, even in out-of-coverage scenarios. The mechanism presented hereafter improves the data rate compared to the current PMR mechanism, by reducing the number of collisions using the LTE physical resource block (RB) structure.