Collision-aware resource access in LTE-based device-to-device communication systems

In the Long Term Evolution (LTE) based device-to-device (D2D) communication systems, there are two resource access modes, i.e., eNB scheduled and random access. The eNB scheduled resource access gives flexibility to eNB with additional signalling overhead. The random access scheme is simple without the eNB control but has the drawback of data collision. In this paper, we propose a collision-aware random access scheme for the D2D communications. The proposed scheme utilizes the feature that there are many unused resources in the data transmission period and all user equipments (UEs) have full information about the resource usage. Before data transmission, the UEs send the resource reservation messages in the unused resource to inform others about the selected resources to be used in the next period. By this means, the D2D UEs can detect the resource reservation messages from each other, and hence can try to select different resources to avoid collision. The performance of the proposed scheme is analyzed and evaluated by simulations. Our results shown that the proposed scheme outperforms the random access scheme by a wide margin in terms of data collision probability.