Mapping of control information to control channel elements
The invention relates to a new structure of a control channel region within a sub-frame of a 3GPP-based based communication system using OFDM in the downlink. This new structure of a control channel region is inter alia particularly suitable for conveying physical downlink control channel information from a donor eNodeB to a relay node. The control channel region is divided in CCEs that have equal size irrespective of the presence of further cell-specific and/or UE-specific reference signals within the control channel region. This is achieved by dividing the control channel region in plural sub-CCEs that are combined to CCEs all having equal size (in terms of resource elements that can be used for the signaling of control information). The control channel region is divided in the frequency domain and/or time domain in a FDM respectively TDM fashion in order to obtain the sub-CCEs.
1. A transmission apparatus comprising:
a configuring circuitry, which in operation, configures a plurality of control channel elements (CCEs) in an extended-physical downlink control channel (extended PDCCH) defined in a physical downlink shared channel (PDSCH) region of a subframe, each of the plurality of CCEs including two sub-CCEs that have different numbers of resource elements (REs), excluding REs configured to map reference signals, in both of a localized mapping scheme where the two sub-CCEs belong to a single resource block pair (RB pair) and a distributed mapping scheme where the two sub-CCEs belong to two different RB pairs;
a mapping circuitry, which in operation, maps downlink control information to at least one of the plurality of CCEs configured in the extended PDCCH; and
a transmitter, which, in operation, transmits the mapped downlink control information.
2. The transmission apparatus according to claim 1 , wherein the two sub-CCEs are selected from a plurality of sub-CCEs that are generated by dividing each of a plurality of RB pairs by frequency and time division.
3. The transmission apparatus according to claim 1 , wherein a number of sub-CCEs that constitute one CCE is common among the plurality of CCEs.
4. The transmission apparatus according to claim 1 , wherein the two sub-CCEs belong to a single RB pair.
5. The transmission apparatus according to claim 1 , wherein the two sub-CCEs belong to more than one RB pairs.
6. The transmission apparatus according to claim 1 , wherein
the subframe comprises a first slot and a second slot in a time domain, and
the digital signal processing circuitry generates each of the plurality of CCEs by combining at least one sub-CCE belonging to the first slot and at least one sub-CCE belonging to the second slot.
7. The transmission apparatus according to claim 1 , wherein the digital signal processing circuitry maps the downlink control information to one CCE or an aggregated several CCEs among the plurality of CCEs configured in the extended-PDCCH.
8. A transmission method comprising:
configuring a plurality of control channel elements (CCEs) in an extended-physical downlink control channel (extended PDCCH) defined in a physical downlink shared channel (PDSCH) region of a subframe, each of the plurality of CCEs including two sub-CCEs that have different numbers of resource elements (REs), excluding REs configured to map reference signals;
mapping downlink control information to at least one of the plurality of CCEs configured in the extended PDCCH, in both of a localized mapping scheme where the two sub-CCEs belong to a single resource block pair (RB pair) and a distributed mapping scheme where the two sub-CCE belongs to two different RB pairs; and
transmitting the mapped downlink control information.
9. The transmission method according to claim 8 , wherein the two sub-CCEs are selected from a plurality of sub-CCEs that are generated by dividing each of a plurality of RB pairs by frequency and time division.
10. The transmission method according to claim 8 , wherein a number of sub-CCEs that constitute one CCE is common among the plurality of CCEs.
11. The transmission method according to claim 8 , wherein the two sub-CCEs belong to a single RB pair.
12. The transmission method according to claim 8 , wherein the two sub-CCEs belong to more than one RB pairs.
13. The transmission method according to claim 8 , wherein
the subframe comprises a first slot and a second slot in a time domain, and
each of the plurality of CCEs is generated by combining at least one sub-CCE belonging to the first slot and at least one sub-CCE belonging to the second slot.
14. The transmission method according to claim 8 , wherein the downlink control information is mapped to one CCE or an aggregated several CCEs among the plurality of CCEs configured in the extended-PDCCH.