Terminal device, infrastructure equipment and methods for resource selection and updating of access class information
A terminal device for use with a wireless telecommunications network includes a transceiver configured to receive information indicative of one or more access classes of terminal devices which are permitted to exchange signals with the wireless telecommunications network, and a controller configured to update, the received information to modify the one or more access classes of terminal devices which are permitted to exchange signals with the mobile telecommunications network, the received information being updated by the controller according to a predetermined function of time.
1. A terminal device for use with a wireless telecommunications network, the terminal device comprising:
a transceiver configured to exchange signals with the wireless telecommunications network using one of a plurality of predetermined radio frequency resources; and
a controller configured to determine a subset of the plurality of predetermined radio frequency resources on the basis of a network characteristic indicative of a network preference for biasing access to each predetermined radio frequency resource and an operational characteristic associated with the terminal device, and to select the one of the plurality of predetermined radio frequency resources from the determined subset.
2. The terminal device according to claim 1 , wherein each of the plurality of predetermined radio frequency resources is a Narrowband Internet of Things (NB-IoT) carrier.
3. The terminal device according to claim 1 , wherein:
the network characteristic indicative of the network preference for biasing access to each predetermined radio frequency resource is a number of access classes of terminal devices which are permitted to exchange signals with the wireless telecommunications network using that predetermined radio frequency resource;
the operational characteristic associated with the terminal device is an access class of the terminal device; and
the controller is configured to include each predetermined radio frequency resource via which terminal devices with the access class of the terminal device are permitted to exchange signals with the wireless telecommunications network in the subset of the plurality of predetermined radio frequency resources.
4. The terminal device according to claim 3 , wherein the controller is configured to select, from the predetermined radio frequency resources of the subset, the predetermined radio frequency resource associated with the largest number of access classes of terminal devices which are permitted to exchange signals with the wireless telecommunications network using that predetermined radio frequency resource as the one of the plurality of predetermined radio frequency resources.
5. The terminal device according to claim 1 , wherein:
the network characteristic indicative of the network preference for biasing access to each predetermined radio frequency resource is a signal quality offset value associated with that predetermined radio frequency resource;
the operational characteristic associated with the terminal device is a signal quality measurement associated with each predetermined radio frequency resource; and
the controller is configured to include, in the subset of the plurality of predetermined radio frequency resources, each predetermined radio frequency resource associated with a modified signal quality measurement which exceeds a predetermined threshold, the modified signal quality measurement associated with each predetermined radio frequency resource being given by the signal quality measurement associated with that predetermined frequency resource added to the signal quality offset value associated with that predetermined radio frequency resource.
6. The terminal device according to claim 1 , wherein:
the network characteristic indicative of the network preference for biasing access to each predetermined radio frequency resource is a signal quality offset value associated with that predetermined radio frequency resource;
the operational characteristic associated with the terminal device is a signal quality measurement associated with each predetermined radio frequency resource; and
the controller is configured to include, in the subset of the plurality of predetermined radio frequency resources, a predetermined radio frequency resource associated with a highest modified signal quality measurement, the modified signal quality measurement associated with each predetermined radio frequency resource being given by the signal quality measurement associated with that predetermined frequency resource added to the signal quality offset value associated with that predetermined radio frequency resource.
7. The terminal device according to claim 5 , wherein the calculation of the signal quality offset value associated with each predetermined radio frequency resource takes into account the effect of a signal quality boosting value associated with that predetermined radio frequency resource.
8. The terminal device according to claim 5 , wherein, for each predetermined radio frequency resource, the signal quality measurement is a Reference Signal Received Power (RSRP) measurement, the signal quality offset value is an RSRP offset value and the modified signal quality measurement is a modified RSRP measurement, wherein the RSRP offset value serves to reduce the modified RSRP measurement relative to the RSRP measurement for a predetermined radio frequency resource with a lower level of network preference for biasing access to that predetermined radio frequency resource and to increase the modified RSRP measurement relative to the RSRP measurement for a predetermined radio frequency resource with a higher level of network preference for biasing access to that predetermined radio frequency resource.
9. The terminal device according claim 1 , wherein:
the network characteristic indicative of the network preference for biasing access to each predetermined radio frequency resource is an access class factor associated with that predetermined radio frequency resource, the access class factor being a value within a predetermined range and being correlated with the level of network preference for biasing access to that predetermined radio frequency resource;
the operational characteristic associated with the terminal device is a randomly generated value within the predetermined range; and
the controller is configured to include, in the subset of the plurality of predetermined radio frequency resources, each predetermined radio frequency resource which either:
in the case that the access class factor of each predetermined radio frequency resource is positively correlated with the level of network preference for biasing access to that radio frequency resource, has an access class factor greater than the randomly generated value of the terminal device; or
in the case that the access class factor of each predetermined radio frequency resource is negatively correlated with the level of network preference for biasing access to that radio frequency resource, has an access class factor less than the randomly generated value of the terminal device.
10. The terminal device according to claim 9 , wherein the predetermined range is from 0 to 1 , and the access class factor is positively correlated with the level of the network preference for biasing access to each predetermined radio frequency resource.
11. The terminal device according to claim 9 , wherein the controller is configured to select, from the predetermined radio frequency resources of the subset, the predetermined radio frequency resource associated with the access class factor which is closest to the randomly generated value of the terminal device.
12. The terminal device according to claim 1 , wherein the controller is configured to select, from the predetermined radio frequency resources of the subset, the predetermined radio frequency resource associated with the highest signal strength or signal quality as the one of the plurality of predetermined radio frequency resources.
13. The terminal device according to claim 1 , wherein the controller is configured to randomly select, from the predetermined radio frequency resources of the subset, the one of the plurality of predetermined radio frequency resources.
14. The terminal device according to claim 1 , wherein the controller is configured to select, from the predetermined radio frequency resources of the subset, the one of the plurality of predetermined radio frequency resources based on an identifier, UE_ID, of the terminal device.
15. The terminal device according to claim 14 , wherein there are n predetermined radio frequency resources in the subset and each predetermined radio frequency resource in the subset is associated with one of a respective integer identifier from 0 to n−1, and the controller is configured to select as the one of the plurality of predetermined radio frequency resources the predetermined radio frequency resource with an identifier which is equal to UE-ID mod n.
16. The terminal device according to claim 14 , wherein each predetermined radio frequency resource in the subset is associated with a respective one or more of predetermined offset values and the controller is configured to select as the one of the plurality of predetermined radio frequency resources a predetermined radio frequency resource associated with an offset value k i which satisfies:
(UE_ID+ k i )mod M=C
wherein M and C are predetermined values.
17. The terminal device according to claim 14 , wherein each predetermined radio frequency resource in the subset is associated with a respective predetermined value M and a respective predetermined value C, and the controller is configured to select as the one of the plurality of predetermined radio frequency resources a predetermined radio frequency resource with respective predetermined values M and C which satisfy:
UE_ID mod M<C.
18. Infrastructure equipment for use with a wireless telecommunications network, the infrastructure equipment comprising:
a controller configured to generate a network characteristic indicative of a network preference for biasing access to each of a plurality of predetermined radio frequency resources by a terminal device of the wireless telecommunications network, the network characteristic determined for each predetermined radio frequency resource being for use by the terminal device in selecting one of the plurality of predetermined radio frequency resources; and
a transceiver configured to:
transmit, to the terminal device, the generated network characteristic indicative of the network preference for biasing access to each of the plurality of predetermined radio frequency resources by the terminal device; and
exchange signals with the terminal device using the one of a plurality of predetermined radio frequency resources.
19. A method of operating a terminal device for use with a wireless telecommunications network, the method comprising:
determining a subset of a plurality of predetermined radio frequency resources on the basis of a network characteristic indicative of a network preference for biasing access to each predetermined radio frequency resource and an operational characteristic associated with the terminal device;
selecting one of the plurality of predetermined radio frequency resources from the determined subset; and
controlling a transceiver of the terminal device to exchange signals with the wireless telecommunications network using the selected one of the plurality of predetermined radio frequency resources.