D2D Communications - What Part Will It Play in 5G?

Device-to-Device (D2D) communication refers to a radio technology that enables devices to communicate directly with each other, that is without routing the data paths through a network infrastructure. Potential application scenarios include, among others, proximity-based services where devices detect their proximity and subsequently trigger different services (such as social applications triggered by user proximity, advertisements, local exchange of information, smart communication between vehicles, etc.). Other applications include public safety support, where devices provide at least local connectivity even in case of damage to the radio infrastructure.

Figure 1: Example application scenarios for Device to Device

With D2D the end users will be able to benefit from a number of services otherwise not possible, such as public safety communication in case of infrastructure damage as well as proximity awareness. In the future D2D may even allow users to experience benefits in terms of smaller communication latency, increased data rate and reduced energy consumption.

In order to develop efficient and scalable D2D technology, Ericsson Research has identified and evaluated the potential gains and technical solutions of network controlled D2D, where the cellular infrastructure controls and assists the efficient operation of D2D links coexisting with cellular communications within the same shared cellular spectrum. The potential gains include:

• Capacity gain: due to the possibility of sharing spectrum resources between cellular and D2D users.
• User data rate gain: due to the close proximity and potentially favorable propagation conditions high peak rates may be achieved.
• Latency gain: when devices communicate over a direct link, the end-to-end latency may be reduced.

However, D2D communication implies new challenges for devices design, interference management, security, mobility management and other aspects. In addition, the success of this technology largely depends on the scenarios in which users in the proximity of each other communicate and the applications that will be developed in the coming years.

Figure 2: Device to Device and Cellular communications share the same radio resources. The network controls and optimizes the use of the resources for both Cellular communication and D2D, resulting in enhanced performance and quality of service.

D2D is currently being specified by 3GPP in LTE Rel-12, focusing on Public Safety applications and proximity-based services (device discovery). Ericsson Research is a main contributor to standardization of Device-to-Device in LTE.

D2D communication is also recognized as one of the technology components of the evolving 5G architecture by the European Union project METIS. METIS stands for Mobile and wireless communications Enablers for the Twenty-twenty Information Society. The main objective of the project is to lay the foundation of 5G, the next generation mobile and wireless communications system. The METIS project is currently evaluating the role that D2D technology can play in various scenarios such as vehicle-to-vehicle communication; national security and public safety, cellular network offloading or service advertisement.

Ericsson Research is actively contributing to METIS in the exciting area of D2D and has summarized its recent findings in use cases, design approaches and performance aspects in a book chapter in “Smart Device to Smart Device Communication” published by Springer.

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