With the evolution of mobile services, various types of service models for using smartphones have recently appeared. As an example, a service provided based on a user's proximity uses a cellular network; however, using a cellular network may cause data congestion as the number of users increases.
In order to resolve the problem, device-to-device (D2D) communication technology using proximity of communication devices has been attracting attention in recent years.
In cellular networks configured to support D2D communication, devices may perform D2D communication, i.e., communication via a direct path, in order to use efficient wireless resources, and this may increase the overall throughput of networks. However, when communication devices are relatively far apart from each other, the performance of a wireless channel is lowered and D2D communication may not be efficient. In this case, it is effective to communicate via a default path of a cellular network.
When devices communicate with the same eNB via the default path, transmission of data packets through a cellular network may increase unnecessary traffic in the network. In order to resolve the problem, there may be a need for communication via a local path on which an eNB serves as a relay for D2D communication without passing through a network.
Therefore, there is a need to adaptively switch a device-to-device communication path to either a direct communication path or a local communication path between devices.