Evaluation of 5G Relay-Empowered and Device-to-Device Communications for Rescue Mission

In public safety scenarios, communication between responders is crucial to ensure better cooperation during rescue missions. Several Mission critical services have been proposed by 3GPP, enabling the exchange of data, voice, and multimedia content over the latest generation of cellular networks. Despite the great popularity of cellular technologies, there are limitations when users exchange large amounts of data traffic at the edge of the antenna. By taking advantage of the proximity between users, deploying Device-to-Device (D2D) communication should offer better bandwidth, lower delays, and optimized device energy consumption. To overcome the range limitations of Direct D2D communication, a multi-hop cooperative relay based on CQI (Channel Quality Indicator) can route the message to the final destination. Two communication modes are thus proposed: (1) the D2D Loosely Coupled mode, which relies exclusively on user-type relays, and (2) the Hybrid mode, which allows the cellular antenna to be used as a relay when routing packets. This paper proposes modeling and evaluation of these solutions in the context of rescue operations, using an extension of the Simu5G library under the OMNeT++ simulator. Several configurations, including different application bitrates, showcase the coverage capabilities and related end-to-end delays when using a multi-relays solution compared to Direct D2D communication. The D2D Loosely coupled and Hybrid modes are evaluated and compared to the Infrastructure mode, particularly when traffic moves to the edge of the cell. Hybrid mode performance has been highlighted through a series of mobility scenarios.