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, the method comprising:
accessing a service at the device;
after a determination that the device is approaching an edge of coverage while the device is accessing the service,
the device receiving, from a first node in the cellular network, a relay discovery command;
the device sending a measurement report to the first node indicating discovered nodes capable of acting as relay nodes;
the device receiving, from the first node, a selection of a suitable node to act as a relay node; and
the device receiving, from the first node, an instruction to initiate a mechanism to switch to accessing the service via the relay node,
wherein the mechanism to switch to accessing the service via the relay node comprises:
the device receiving a relay mode proceed indication from the first node; and
the device receiving a connection release message from the first node.
2. The method of claim 1 , wherein the selected suitable node is configured as a relay node prior to receipt of the instruction to initiate 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 1 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
5. 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.
6. The method of claim 1 , wherein the mechanism to switch to accessing the service via the relay node further comprises:
after receiving the relay mode proceed indication from the first node, the device sending a relay mode entered indication to the first node; and wherein
the device receiving a connection release message from the first node occurs upon a determination that a radio resource control connection between the device and a serving cell does not need to be maintained.
7. 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 the device for:
accessing a service at the device;
after a determination that the device is approaching an edge of coverage while the device is accessing the service,
the device receiving, from a first node in the cellular network, a relay discovery command;
the device sending a measurement report to the first node indicating discovered nodes capable of acting as relay nodes;
the device receiving, from the first node, a selection of a suitable node to act as a relay node; and
the device receiving, from the first node, an instruction to initiate a mechanism to switch to accessing the service via the relay node,
wherein the mechanism to switch to accessing the service via the relay node comprises:
the device receiving a relay mode proceed indication from the first node; and
the device receiving a connection release message from the first node.
8. The computer program product of claim 7 , wherein the service is a mission critical push-to-talk over Long Term Evolution service.
9. The computer program product of claim 7 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
10. The computer program product of claim 7 , 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.
11. The computer program product of claim 7 , wherein the mechanism to switch to accessing the service via the relay node comprises:
the device receiving a relay mode proceed indication from the first node;
the device sending a relay mode entered indication to the first node; and
the device receiving a connection release message from the first node upon a determination that a radio resource control connection between the device and a serving cell does not need to be maintained.
12. The computer program product of claim 7 , wherein the mechanism to switch to accessing the service via the relay node further comprises:
after receiving the relay mode proceed indication from the first node, the device sending a relay mode entered indication to the first node; and wherein
the device receiving a connection release message from the first node occurs upon a determination that a radio resource control connection between the device and a serving cell does not need to be maintained.
13. A mobile device, comprising:
a processor;
a communication subsystem communicatively coupled with the processor, the processor configured to:
access a service;
after a determination that the device is approaching an edge of coverage while the device is accessing the service,
receive, from a first node in a cellular network, a relay discovery command;
send a measurement report to the first node indicating discovered nodes capable of acting as relay nodes;
receive, from the first node, a selection of a suitable node to act as a relay node; and
receive, from the first node, an instruction to initiate a mechanism to switch to accessing the service via the relay node,
wherein the mechanism to switch to accessing the service via the relay node comprises:
the device receiving a relay mode proceed indication from the first node; and
the device receiving a connection release message from the first node.
14. The mobile device of claim 13 , wherein the service is a mission critical push-to-talk over Long Term Evolution service.
15. The mobile device of claim 13 , wherein the relay node is a user equipment acting as a user equipment-to-network relay node.
16. The mobile device of claim 13 , 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.
17. The mobile device of claim 13 , wherein the mechanism to switch to accessing the service via the relay node comprises:
the device receiving a relay mode proceed indication from the first node;
the device sending a relay mode entered indication to the first node; and
the device receiving a connection release message from the first node upon a determination that a radio resource control connection between the device and a serving cell does not need to be maintained.
18. The mobile device of claim 13 , wherein the mechanism to switch to accessing the service via the suitable relay further comprises:
after receiving the relay mode proceed indication from the first node, the device receiving a connection release message from the first node; and wherein
the device receiving a connection release message from the first node occurs upon a determination that a radio resource control connection between the device and a serving cell does not need to be maintained.