Control channel communications in a cellular communications network
A communications device in the form of a base station or communications node such as an eNodeB communications node selects one of a plurality of modulation and coding schemes for a control channel for a user communications device on the basis of the range which is specified by the location or channel condition within a cell of the user communications device. The selected modulation and coding scheme are identified to the user communications device separately from the control channel. In one example, the selected modulation and coding scheme is identified to the user communications device by way of a 2-bit code which may be provided within a MAC control block or appended to a MAC Data PDU.
1. A method of control channel communication within a cellular communications network, the method comprising:
determining, within a cell of the cellular communications network, data which relates to a range of a user communications device and which is determined by a distance from a base station;
selecting at least one of a plurality of modulation and coding schemes for a control channel for that communications device on a basis of the determined range data, the selected modulation and coding scheme being dependent on the distance between the user communications and the base station;
separately identifying the selected modulation and coding scheme to the user communications device;
providing a control channel for that user communications device using the selected modulation and coding scheme, by making the control channel correspond to an aggregation of control channel elements (CCEs) concerned with the selected modulation and coding scheme; and
transmitting the aggregation of the CCEs to the user communications device.
2. A method according to claim 1 , wherein the plurality of modulation and coding schemes each have a different coding rate,
wherein the control channel is provided as the aggregation of the CCEs, each of the CCEs comprising a number of resource elements, and
wherein a number of the CCEs in the control channel depending upon the selected modulation and coding scheme.
3. A communications device comprising:
a determiner to determine data which relates to a range of a user communications device within a cell of a cellular network;
a selector to select at least one of a plurality of modulation and coding schemes for a control channel for that user communications device on a basis of the determined range;
an identifier to separately identify the selected modulation and coding scheme to the user communications device;
a provider to provide a control channel for that user communications device using the selected modulation and coding scheme, by making the control channel correspond to an aggregation of control channel elements (CCEs) concerned with the selected modulation and coding scheme; and
a transmitter to transmit the aggregation of the CCEs to the user communications device through the control channel.
4. A communications device according to claim 3 , wherein the identifier is operable to identify the selected modulation and coding scheme to the user communications device using a higher communications protocol layer.
5. A communications device according to claim 3 , wherein the plurality of modulation and coding schemes each have a different coding rate.
6. A communications device according to claim 3 , wherein the provider is operable to provide the control channel as the aggregation of the CCEs, each of the CCEs comprising a number of resource elements, and
wherein a number of the CCEs in the control channel depending upon the selected modulation and coding scheme.
7. A communications device according to claim 3 , wherein the plurality of modulation and coding schemes each use a same modulation scheme.
8. A communications device according to claim 3 , further comprising a receiver to receive an acknowledgement message indicating a receipt of the identity of the selected modulation and coding scheme by the user communications device.
9. A communications device according to claim 3 , wherein the determiner is operable to determine data relating to the range of a user communications device within the cell of the communications device by determining which of a number of communications regions successively further from the communications device the user communications device is in.
10. A communications device according to claim 9 , wherein each communications region is associated with a respective different one of the modulation and coding schemes.
11. A method of communicating in a cellular communications network, the method comprising a user communications device:
receiving from a communications node identification data identifying which one of a plurality of modulation and coding schemes is selected for a control channel for the user communications device; and
identifying the control channel using the received identification data identifying the one of the plurality of modulation and coding schemes selected for the control channel, by detecting an aggregation of control channel elements (CCEs) that is concerned with the selected modulation and coding scheme.
12. A method according to claim 11 , which further comprises using the identification data to determine an aggregate number of the CCEs forming the control channel.
13. A user communications device for use in a cellular communications network, the user communications device comprising:
a receiver to receive from a communications node identification data identifying one of a plurality of modulation and coding schemes selected for a control channel for the user communications device; and
an identifier to identify the control channel using the received identification data identifying the one of the plurality of modulation and coding schemes selected for the control channel, by detecting an aggregation of control channel elements (CCEs) that is concerned with the selected modulation and coding scheme.
14. A user communications device according to claim 13 , wherein the identifier is operable to use the identification data to determine an aggregate number of the CCEs forming the control channel.
15. A user communications device according to claim 13 , further comprising an acknowledger to send an acknowledgement message upon receipt of the identification data.
16. A communications device according to claim 3 , wherein the determiner is operable to determine the range of a user communications device on a basis of at least one of:
an actual distance of the user communications device from the communications device;
an average SNR (signal to noise ratio); and
a channel quality indicator (CQI).
17. A non-transitory computer implementable instructions product comprising computer implementable instructions for programming a programmable computer device to carry out a method in accordance with claim 1 .
18. A non-transitory computer implementable instructions product comprising computer implementable instructions for programming a programmable computer device to carry out a method in accordance with claim 11 .
19. A user communications device according to claim 14 , wherein the identifier is operable to monitor subsets of the CCEs on a basis of the aggregated number of CCEs determined from the received identification data in order to identify the control channel.
20. A user communications device according to claim 13 , wherein the receiver is operable to receive respective identification data for uplink and downlink control channels.