CLUSTER HEAD ASSISTED METHOD FOR CONVERTING USER TERMINAL FROM D2D COMMUNICATION TO CELLULAR COMMUNICATION

摘要

The present invention discloses a cluster head assisted method for converting a user terminal from device-to-device (D2D) communication to cellular communication. When quality of a D2D link between a user terminal and a cluster head is lower than a predetermined threshold, if the user terminal has to leave the cluster but still expects to continue an original the service, the user terminal performs cell search and random access, and establishes a radio resource control (RRC) connection with a target base station of a cellular network. Switching from D2D communication to cellular communication is implemented with the assistance of the cluster head, and a communication manner after the switching is provided. The present invention implements mobile switching from D2D communication in distributed cluster communication to cellular communication, which can reduce route search delay and save wireless resources.

主权项

1. A cluster head assisted method for converting a user terminal from device-to-device (D2D) communication to cellular communication, comprising following steps:
Step 1: if the quality of a D2D link between a user terminal and a cluster head is lower than a predetermined threshold, the user terminal performing cell search and a random access process to access a cellular network; and Step 2: the user terminal sending a switching request to the cluster head through a D2D link, wherein the switching request comprises an ID of a target base station to which the user terminal is going to access; and the cluster head sending the switching request to a serving base station through a cellular link, wherein the ID of the target base station to which the user terminal is going to access is the same as an ID of the serving base station where the cluster head belongs, indicating that the target base station to which the user terminal is going to access and the serving base station where the cluster head belongs are the same base station, the user terminal accesses the serving base station where the cluster head belongs, and establishes a radio resource control (RRC) connection with the serving base station; the serving base station replies a switching response message to the cluster head through the cellular link; and the cluster head sends switching response information to the user terminal through the D2D link; and if the ID of the target base station to which the user terminal is going to access is different from an ID of the serving base station where the cluster head belongs, the user terminal accesses the target base station, and establishes an RRC connection with the target base station; the serving base station forwards the switching request of the user terminal to the target base station, and the target base station replies a switching response message to the serving base station.