Telecommunications apparatus and methods
A wireless telecommunications system in which downlink communications are made using a radio interface that spans a system frequency bandwidth (host carrier) and supports at least some communications from a base station to least some terminal devices within a plurality of restricted frequency bands (virtual carriers) which are narrower than and within the system frequency bandwidth. A terminal device conveys an indication of its identity, e.g. an IMSI, to the base station during an initial connection procedure as the terminal device seeks to access the radio interface. The terminal device and the base station both determine a selected restricted frequency band from among the plurality of restricted frequency bands based on the identity of the terminal device in the same way. Thus the terminal device and the base station select the same restricted frequency band and can accordingly configure their respective transceivers to allow for downlink communications between them within the selected restricted frequency band.
1. Circuitry for infrastructure equipment in a wireless telecommunications system in which downlink communications are made by the infrastructure equipment using a radio interface that spans a system frequency bandwidth and supports at least some communications with at least some terminal devices within a plurality of narrowband channels bands which are narrower than and within the system frequency bandwidth, the circuitry configured to:
select a narrowband channel to be used for downlink communications for a terminal device from among the plurality of narrowband channels based on an identifier for the terminal device; and
transmit downlink communications to the terminal device within the selected narrowband channel.
2. The circuitry of claim 1 , wherein the identifier for the terminal device comprises an International Mobile Subscriber Identity, IMSI, associated with the terminal device.
3. The circuitry of claim 1 , wherein the selected narrowband channel is determined from a remainder value obtained when dividing a number associated with the identifier for the terminal device by the number of the plurality of narrowband channels supported by the infrastructure equipment base station.
4. The circuitry of claim 1 , wherein the circuitry is configured to convey configuration information relating to the plurality of narrowband channels supported by the infrastructure equipment to the terminal device in system information transmitted by the infrastructure equipment.
5. The circuitry of claim 4 , wherein the configuration information comprises an indication of the number of the plurality of narrowband channels supported by the infrastructure equipment and/or an indication of frequencies for the narrowband channels.
6. The circuitry of claim 1 , wherein the circuitry is configured to convey configuration information relating to the plurality of narrowband channels supported by the infrastructure equipment to the terminal device before or during an initial connection procedure for the terminal device on the radio interface.
7. The circuitry of claim 6 , wherein the configuration information comprises an indication of the number of the plurality of narrowband channels supported by the infrastructure equipment and/or an indication of frequencies for the narrowband channels.
8. The circuitry of claim 1 , wherein configuration information relating to the plurality of narrowband channels supported by the infrastructure equipment is predefined for the wireless telecommunications system.
9. The circuitry of claim 8 , wherein the configuration information comprises an indication of the number of the plurality of narrowband channels supported by the infrastructure equipment and/or an indication of frequencies for the narrowband channels.
10. The circuitry of claim 1 , wherein downlink communications transmitted to the terminal device within the selected narrowband channel comprise user-plane data and control-plane data, and wherein the control-plane data comprise an indication of resources within the selected narrowband channel to be used for communicating the user-plane data.
11. The circuitry of claim 1 , wherein the downlink communications transmitted to the terminal device within the selected narrowband channel comprise user-plane data, and wherein the circuitry is configured to transmit control-plane data to the terminal device on frequency resources from across the system frequency bandwidth, wherein the control-plane data comprise an indication of resources within the selected narrowband channel to be used for communicating the user-plane data.
12. The circuitry of claim 1 , wherein the circuitry is configured to receive an indication of the identifier for the terminal device from the terminal device.
13. The circuitry of claim 12 , wherein the indication of the identifier for the terminal device is received from the terminal device before or during an initial connection procedure for the terminal device on the radio interface.
14. The circuitry of claim 12 , wherein the indication of the identifier for the terminal device is received from the terminal device in association with radio resource control, RRC, connection request signalling.
15. A method of operating an infrastructure equipment in a wireless telecommunications system in which downlink communications are made by the infrastructure equipment using a radio interface that spans a system frequency bandwidth and supports at least some communications with at least some terminal devices within a plurality of narrowband channels which are narrower than and within the system frequency bandwidth, the method comprising:
selecting a narrowband channel to be used for downlink communications for a terminal device from among the plurality of narrowband channels based on an identifier for the terminal device; and
transmitting downlink communications to the terminal device within the selected narrowband channel.
16. Infrastructure equipment for a wireless telecommunications system in which downlink communications are made by the infrastructure equipment using a radio interface that spans a system frequency bandwidth and supports at least some communications with at least some terminal devices within a plurality of narrowband channels which are narrower than and within the system frequency bandwidth, the infrastructure equipment comprising:
circuitry configured to
select a narrowband channel to be used for downlink communications for a terminal device from among the plurality of narrowband channels based on an identifier for the terminal device; and
transmit downlink communications to the terminal device within the selected narrowband channel.
17. The infrastructure equipment of claim 16 , wherein the circuitry is configured to convey configuration information relating to the plurality of narrowband channels supported by the infrastructure equipment to the terminal device in system information transmitted by the infrastructure equipment.
18. The infrastructure equipment of claim 17 , wherein the configuration information comprises an indication of the number of the plurality of narrowband channels supported by the infrastructure equipment and/or an indication of frequencies for the narrowband channels.
19. The infrastructure equipment of claim 16 , wherein the circuitry is configured to convey configuration information relating to the plurality of narrowband channels supported by the infrastructure equipment to the terminal device before or during an initial connection procedure for the terminal device on the radio interface.
20. The infrastructure equipment of claim 16 , wherein the configuration information comprises an indication of the number of the plurality of narrowband channels supported by the infrastructure equipment and/or an indication of frequencies for the narrowband channels.