Long-term evolution device-to-device discovery using control channel
Device-to-device (D2D) communications between user equipment (UE) allows two UEs in a long-term evolution (LTE) network to communicate directly with each other without the need to first send their communications to a network (such as via an evolved node B). In order to communicate in a D2D mode, the UEs first need to discover each other. One method of allowing the UEs to discover each other involves the use of a physical uplink control channel (PUCCH). After a network determines that certain UEs would benefit from D2D communication, the UEs can be set up to send and receive discovery signals using the PUCCH.
1. A method for facilitating the establishment of a device-to-device (D2D) connection in a long term evolution (LTE) network comprising:
detecting, by an evolved NodeB (eNB) a possibility to offload communications to D2D communications between a first user equipment (UE) and a second UE based at least in part on a proximity of the first UE to the second UE being within a threshold range;
scheduling, by the eNB, the first UE to transmit a D2D discovery signal via a physical uplink control channel (PUCCH) during a D2D grant from the eNB;
informing a second UE of the D2D discovery signal, wherein the informing comprises configuring a measurement period of the PUCCH;
determining if the second UE is able to detect the D2D discovery signal; and
if the second UE is able to detect the D2D discovery signal, then establishing a D2D connection between the first UE and the second UE.
2. The method of claim 1 wherein the D2D discovery signal is transmitted using PUCCH format 1.
3. The method of claim 1 wherein determining if the second UE is able to detect the D2D discovery signal comprises receiving a report from the second UE, the report comprising information regarding the ability of the second UE to detect the D2D discovery signal.
4. The method of claim 3 wherein the report further comprises channel quality information between the first UE and the second UE.
5. The method of claim 4 wherein determining if the second UE is able to detect the D2D discovery signal further comprises comparing the channel quality information to a predetermined threshold.
6. The method of claim 1 wherein the second UE is a member of a group of UEs.
7. The method of claim 6 further comprising:
determining if there are other UEs in the group of UEs that are able to detect the D2D discovery signal sent via PUCCH; and
establishing a D2D connection between the first UE and any UE of the group of UEs that is able to detect the D2D discovery signal.
8. The method of claim 1 wherein informing a second UE of the D2D discovery signal further comprises
providing information regarding which signal is to be used in the PUCCH; wherein the signal to be used is chosen from scheduling request (SR) resource, SR configuration index, cell radio network temporary identifier (C-RNTI), and D2D radio network temporary identifier (D-RNTI).
9. The method of claim 1 wherein scheduling a first user equipment (UE) to transmit a D2D discovery signal using a physical uplink control channel (PUCCH) comprises scheduling the first UE to transmit the D2D discovery signal at every potential scheduling request (SR) subframe at a predetermined SR resource and SR configuration index.
10. An evolved node B (eNB) arranged to facilitate the establishment of a device-to-device (D2D) connection in a long term evolution (LTE) network comprising:
a processor;
an antenna assembly; and
a transceiver coupled to the processor, wherein the transceiver is arranged to transmit and receive signals via the antenna assembly;
wherein the processor is arranged to:
detect a possibility to offload communications to D2D communications between a first user equipment (UE) and a second UE based at least in part on a proximity of the first UE to the second UE being within a threshold range;
schedule the first UE to transmit a D2D discovery signal via a physical uplink control channel (PUCCH) during a D2D grant from the eNB, wherein scheduling the first UE is accomplished by transmitting a signal to the first UE via the transceiver;
inform a second UE of the D2D discovery signal sent via the PUCCH, wherein informing the second UE is accomplished by transmitting a signal to the second UE via the transceiver, and wherein the informing comprises configuring a measurement period of the PUCCH;
determine if the second UE is able to detect the D2D discovery signal;
if the second UE is able to detect the D2D discovery signal, then establish a D2D connection between the first UE and the second UE; and
if the second UE is not able to detect the D2D discovery signal, serving the first UE and the second UE via LTE couplings from the eNB to the first UE and to the second UE.
11. The eNB of claim 10 wherein determining if the second UE is able to detect the D2D discovery signal comprises receiving a report from the second UE, the report comprising information regarding the ability of the second UE to detect the D2D discovery signal.
12. The eNB of claim 11 wherein the report further comprises channel quality information between the first UE and the second UE.
13. The eNB of claim 12 wherein determining if the second UE is able to detect the D2D discovery signal further comprises comparing the channel quality information to a predetermined threshold.
14. The eNB of claim 10 wherein the second UE is a member of a group of UEs.
15. The eNB of claim 14 wherein the processor is further arranged to:
determine if there are other UEs in the group of UEs that are able to detect the D2D discovery signal on the PUCCH, and
establish a D2D connection between the first UE and any UE of the group of UEs that is able to detect the D2D discovery signal.
16. The eNB of claim 10 wherein informing a second UE of the D2D discovery signal via PUCCH further comprises
providing information regarding which signal is to be used in the PUCCH, wherein the signal to be used is chosen from scheduling request (SR) resource, SR configuration index, cell radio network temporary identifier (C-RINTI), and D2D radio network temporary identifier (D-RNTI).
17. The eNB of claim 10 wherein scheduling a first user equipment (UE) to transmit a D2D discovery signal via a physical uplink control channel (PUCCH) comprises scheduling the first UE to transmit the D2D discovery signal at every potential scheduling request (SR) subframe at a predetermined SR resource and SR configuration index.
18. The eNB of claim 10 wherein the D2D discovery signal is scheduled to be sent via PUCCH using
PUCCH format 1.
19. A method performed by a user equipment (UE) for facilitating the establishment of a device-to-device (D2D) connection in a long term evolution (LTE) network comprising:
providing positioning information to a network;
responsive to providing the positioning information, receiving instructions from the network to transmit a D2D discovery signal;
transmitting a D2D discovery signal via a physical uplink control channel (PUCCH) during a D2D grant from the network; and
if a second UE is able to detect the D2D discovery signal, establishing a D2D connection with the second UE, wherein the second UE is informed, by an evolved node B (eNB), of the D2D discovery signal sent via the PUCCH, and wherein the informing comprises configuring a measurement period of the PUCCH.
20. The method of claim 19 wherein the instructions comprise:
a predetermined scheduling request (SR) resource and SR configuration index.
21. The method of claim 20 wherein transmitting a D2D discovery signal comprises:
transmitting the D2D discovery signal at every potential SR subframe at the predetermined SR resource and SR configuration index.
22. The method of claim 19 wherein the D2D discovery signal is chosen from a scheduling request (SR) resource, SR configuration index, cell radio network temporary identifier (C-RNTI), and D2D radio network temporary identifier (D-RNTI).
23. The method of claim 19 wherein the D2D discovery signal sent via PUCCH is sent using PUCCH format 1.