Switching between network based and relay based operation for mission critical voice call
A device, serving cell and method of switching between modes of operation for the device in a cellular network comprises receiving a service via a connection with the serving cell. A condition indicative of deterioration in network service and an absence of a suitable neighbor cell are detected. In response, discovery of relay nodes is initiated. When a suitable relay node is discovered, a mechanism to switch to receiving the service via the suitable relay node is initiated. The service may be a mission critical push-to-talk over Long Term Evolution service. The relay node may be user equipment acting as a user equipment-to-network relay node. When the device is in an RCC_CONNECTED state, the mechanism to switch includes sending a relay mode preference indication to the serving cell, receiving a connection release message from the serving cell, releasing the serving cell connection, and establishing a sidelink connection with the relay.
1. A method of switching between modes of operation for a device in a cellular network implemented by a first node in the cellular network, comprising:
providing a service to the device;
determining, while providing the service to the device, that the device is approaching an edge of coverage;
responsive to determining that the device is approaching the edge of coverage, the first node sending a relay discovery command to the device;
receiving a measurement report from the device indicating discovered nodes capable of acting as relay nodes;
the first node selecting a suitable node to act as a relay node; and
the first node instructing initiation of a mechanism to switch to accessing the service via the relay node.
2. The method of claim 1 , further comprising:
upon selecting a suitable node to act as a relay node, configuring the node as a relay node prior to instructing initiation of the mechanism to switch to accessing the service via the relay node.
3. The method of claim 1 , wherein the service is a mission critical push-to-talk over Long Term Evolution service.
4. The method of claim 3 , wherein the mechanism to switch to accessing the service via the suitable relay comprises:
sending a relay mode proceed indication to the device; and
sending a connection release message to the device.
5. The method of claim 1 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
6. The method of claim 1 , wherein the measurement report comprises, for each discovered node, at least one of the following parameters:
received signal power;
quality measurements;
an L2 source address;
a battery level; or
an available processing power.
7. The method of claim 1 , wherein the mechanism to switch to accessing the service via the relay node comprises:
sending a relay mode proceed indication to the device;
receiving a relay mode entered indication from the device;
determining that a radio resource control connection between the device and a serving cell does not need to be maintained; and
sending a connection release message to the device.
8. A computer program product for enabling switching between modes of operation for a device in a cellular network, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code comprising instructions for execution by a first node in the cellular network for:
providing a service to the device;
determining, while providing the service to the device, that the device is approaching an edge of coverage;
responsive to determining that the device is approaching the edge of coverage, the first node sending a relay discovery command to the device;
receiving a measurement report from the device indicating discovered nodes capable of acting as relay nodes;
the first node selecting a suitable node to act as a relay node; and
the first node instructing initiation of a mechanism to switch to accessing the service via the relay node.
9. The computer program product of claim 8 , further comprising instructions for, upon selecting a suitable node to act as a relay node, configuring the node as a relay node prior to instructing initiation of the mechanism to switch to accessing the service via the relay node.
10. The computer program product of claim 8 , wherein the service is a mission critical push-to-talk over Long Term Evolution service.
11. The computer program product of claim 10 , wherein the mechanism to switch to accessing the service via the suitable relay comprises:
sending a relay mode proceed indication to the device; and
sending a connection release message to the device.
12. The computer program product of claim 8 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
13. The computer program product of claim 8 , wherein the measurement report comprises, for each discovered node, at least one of the following parameters:
received signal power;
quality measurements;
an L2 source address;
a battery level; or
an available processing power.
14. The computer program product of claim 8 , wherein the mechanism to switch to accessing the service via the suitable relay comprises:
sending a relay mode proceed indication to the device;
receiving a relay mode entered indication from the device;
determining that a radio resource control connection between the device and a serving cell does not need to be maintained; and
sending a connection release message to the device.
15. A serving cell, comprising:
a processor;
a communication subsystem communicatively coupled with the processor, the processor configured to:
provide a service to the device;
determine, while providing the service to the device, that the device is approaching an edge of coverage;
responsive to determining that the device is approaching the edge of coverage, send a relay discovery command to the device;
receive a measurement report from the device indicating discovered nodes capable of acting as relay nodes;
select a suitable node to act as a relay node; and
instruct initiation of a mechanism to switch to accessing the service via the relay node.
16. The serving cell of claim 15 , wherein the processor is further configured to:
upon selecting a suitable node to act as a relay node, configure the node as a relay node prior to instructing initiation of the mechanism to switch to accessing the service via the relay node.
17. The serving cell of claim 15 , wherein the service is a mission critical push-to-talk over Long Term Evolution service.
18. The serving cell of claim 17 , wherein the mechanism to switch to accessing the service via the suitable relay comprises:
sending a relay mode proceed indication to the device; and
sending a connection release message to the device.
19. The serving cell of claim 15 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
20. The serving cell of claim 15 , wherein the measurement report comprises, for each discovered node, at least one of the following parameters:
received signal power;
quality measurements;
an L2 source address;
a battery level; or
an available processing power.
21. The serving cell of claim 15 , wherein the mechanism to switch to accessing the service via the relay node comprises:
sending a relay mode proceed indication to the device;
receiving a relay mode entered indication from the device;
determining that a radio resource control connection between the device and a serving cell does not need to be maintained; and
sending a connection release message to the device.