SRS-based D2D neighbor discovery scheme for LTE cellular networks

Device-to-Device (D2D) communication is one of the key technologies in Long Term Evolution-Advanced (LTE-A) systems to improve network capacity and resource utilization. In this paper, we address the problem of neighbor discovery as an enabler of D2D communications that overlay the LTE-A network and share its resources. The proposed scheme allows distributed neighbor discovery for synchronized D2D users by simply listening to peer UpLink (UL) signals. In particular, the Sounding Reference Signals (SRS) are here exploited as beacons to detect potential users willing to initiate direct communication. This signal, which is built from Zadoff-Chu (ZC) sequences, not only possesses robust detection properties, but also has minimal overhead as no additional signals are required to identify the whole set of users and to achieve the discovery procedure. Moreover, for complexity reduction, we suggest a recursive implementation of the proposed discovery metric to adapt it for practical D2D communication scenarios.