DL control channel structure enhancement

1. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor and in response to execution of the computer program code, cause the apparatus to perform at least the following:

receiving signaling indicating whether the apparatus is to access one or both of a first downlink control region in a downlink subframe and an enhanced downlink control region in the downlink subframe, wherein the downlink subframe has a downlink transmission bandwidth and a time duration;

accessing in the first downlink control region a common downlink control channel message;

in response to the received signaling indicating the apparatus is to access the first downlink control region, accessing in the first downlink control region a downlink control channel message corresponding to the apparatus and comprising quadruplets of contiguous subcarriers spread over a plurality of physical resource blocks spread over the whole downlink transmission bandwidth for the first downlink control region, each quadruplet occupying a portion but not all of a physical resource block, and depending on the downlink control channel message accessing or not accessing a portion specific to the apparatus of a first physical downlink shared channel in the downlink subframe; and

in response to the received signaling indicating the apparatus is to access the enhanced downlink control region, accessing in the enhanced downlink control region a downlink control channel message corresponding to the apparatus and comprising a plurality of subcarriers occupying one or more physical resource blocks contiguous in one or both of time and frequency, and depending on the determined downlink control channel message, accessing or not accessing a portion specific to the apparatus of a second physical downlink shared channel in the downlink subframe.

2. The apparatus of claim 1 , wherein the downlink control channel message occupies at least two physical resource blocks contiguous in frequency.

3. The apparatus of claim 1 , wherein the enhanced downlink control region occurs in time after the first downlink control region occurs in time in the downlink subframe.

4. The apparatus of claim 1 , wherein the enhanced downlink control region does not occupy all of the downlink transmission bandwidth.

5. The apparatus of claim 1 , wherein accessing in the enhanced downlink control region a downlink control channel message corresponding to the apparatus further comprises searching an apparatus specific search space in the enhanced downlink control region and decoding the downlink control channel message corresponding to the apparatus.

6. The apparatus of claim 1 , wherein the received signaling indicates that the apparatus is to access both the first downlink control region and the enhanced control region.

7. The apparatus of claim 5 , wherein decoding the downlink control channel corresponding to the apparatus further comprises using information regarding a precoding method used in an encoding process of the downlink control channel message corresponding to the apparatus in order to decode the downlink control channel message.

8. The apparatus of claim 7 , wherein decoding the downlink control channel message corresponding to the apparatus further comprises utilizing one or more reference signals in the downlink control channel which are specific to the apparatus when decoding the downlink control channel message corresponding to the apparatus.

9. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor and in response to execution of the computer program code, cause the apparatus to perform at least the following:

signaling a user equipment to indicate whether the user equipment is to access one or both of a first downlink control region in a downlink subframe and an enhanced downlink control region in the downlink subframe, wherein the downlink subframe has a downlink transmission bandwidth and a time duration;

placing in the first downlink control region a common downlink control channel message corresponding to at least the user equipment;

in response to signaling indicating the user equipment is to access the first downlink control region, placing in the first downlink control region a downlink control channel message corresponding to the user equipment and comprising quadruplets of contiguous subcarriers spread over a plurality of physical resource blocks spread over the whole downlink transmission bandwidth for the first downlink control region, each quadruplet occupying a portion but not all of a physical resource block, and depending on the downlink control channel message placing or not placing a portion specific to the user equipment of a first physical downlink shared channel in the downlink subframe;

in response to signaling indicating the user equipment is to access the enhanced downlink control region, placing in the enhanced downlink control region a downlink control channel message corresponding to the user equipment and comprising a plurality of subcarriers occupying one or more physical resource blocks contiguous in one or both of time and frequency, and depending on the determined downlink control channel message, placing or not placing a portion specific to the user equipment of a second physical downlink shared channel in the downlink subframe; and

transmitting the subframe.

10. The apparatus of claim 9 , wherein the enhanced downlink control region occurs in time after the first downlink control region occurs in time in the downlink subframe.

11. The apparatus of claim 9 , wherein the enhanced downlink control region does not occupy all of the downlink transmission bandwidth.

12. The apparatus of claim 9 , where a size of the bandwidth used for the enhanced downlink control region is configured specific to a cell in which the apparatus exists.

13. The apparatus of claim 9 , wherein placing in the enhanced downlink control region a downlink control channel message corresponding to the user equipment further comprises:

determining a precoding method and related precoding weights to apply to information in the downlink control channel message corresponding to the user equipment;

applying the determined precoding weights to the information to create precoded information; and

placing the precoded information in the downlink control channel message corresponding to the user equipment.

14. The apparatus of claim 9 , wherein the signaling indicates that the user equipment is to access both the first downlink control region and the enhanced control region.

15. The apparatus of claim 13 , wherein placing in the enhanced downlink control region a downlink control channel message corresponding to the user equipment further comprises:

placing one or more reference signals specific to the user equipment in the downlink control channel message corresponding to the user equipment, where a same precoding method and precoding weights applied to the information are applied to the reference signals specific to the user equipment.