DL backhaul control channel design for relays
Methods and apparatus are described for providing compatible mapping for backhaul control channels, frequency first mapping of control channel elements (CCEs) to avoid relay-physical control format indicator channel (R-PCFICH) and a tree based relay resource allocation to minimize the resource allocation map bits. Methods and apparatus (e.g., relay node (RN)/evolved Node-B (eNB)) for mapping of the Un downlink (DL) control signals, Un DL positive acknowledgement (ACK)/negative acknowledgement (NACK) and/or relay-physical downlink control channel (R-PDCCH) (or similar) in the eNB to RN (Un interface) DL direction are described. This includes time/frequency mapping of above-mentioned control signals into resource blocks (RBs) of multimedia broadcast multicast services (MBMS) single frequency network (MBSFN)-reserved sub-frames in the RN cell and encoding procedures for these. Also described are methods and apparatus for optimizing signaling overheads by avoiding R-PCFICH and minimizing bits needs for resource allocation.
1. A method implemented in a relay node (RN) for receiving a relay physical downlink control channel (R-PDCCH), the method comprising:
receiving an R-PDCCH transmission from an evolved Node B (eNB) in subframe configured by the RN as a multimedia broadcast multicast services (MBMS) single frequency network (MBSFN) subframe; and
decoding R-PDCCH bits, wherein the R-PDCCH bits are mapped first in a frequency domain of an orthogonal frequency division multiplexing (OFDM) symbol and second in a time domain across one or more OFDM symbols.
2. The method of claim 1 , wherein the decoded R-PDCCH bits are mapped to a predetermined number of resource blocks (RBs) and the predetermined number of RBs is indicated in a radio resource control (RRC) message.
3. The method of claim 1 , wherein the R-PDCCH transmission indicates a downlink resource assignment is also included in the subframe containing the R-PDCCH transmission.
4. The method of claim 1 , wherein the R-PDCCH transmission begins at a starting OFDM symbol and is received on a subset of the OFDM symbols included in the subframe containing the R-PDCCH transmission.
5. The method of claim 4 , wherein the starting OFDM symbol is not the first OFDM symbol of the subframe including the R-PDCCH transmission.
6. The method of claim 1 , wherein resource block (RB) allocations of the R-PDCCH are at least one of a resource allocation type 0, a resource allocation type 1, or a resource allocation type 2.
7. The method of claim 6 , wherein the RB allocation of the R-PDCCH is a resource allocation of type 2 and comprises an allocation of distributed virtual resource blocks (VRBs).
8. A relay node (RN) for receiving a relay physical downlink control channel (R-PDCCH), the RN comprising:
a receiver configured to receive an R-PDCCH transmission from an evolved Node B (eNB) in subframe configured by the RN as a multimedia broadcast multicast services (MBMS) single frequency network (MBSFN) subframe; and
a processor configured to:
demodulate the R-PDCCH, and
decode R-PDCCH bits, wherein the decoded R-PDCCH bits are mapped first in a frequency domain of an orthogonal frequency division multiplexing (OFDM) symbol and second in a time domain across one or more OFDM symbols.
9. The RN of claim 8 , wherein resource block (RB) allocations of the R-PDCCH are at least one of a resource allocation type 0, a resource allocation type 1, or a resource allocation type 2.
10. The RN of claim 9 , wherein the RB allocation for the R-PDCCH is a resource allocation of type 2 and comprises an allocation of distributed virtual resource blocks (VRBs).
11. The RN of claim 8 , wherein the decoded R-PDCCH bits are mapped to a predetermined number of resource blocks (RBs) and the receiver is further configured to receive a radio resource control (RRC) message indicating the predetermined number of RBs.
12. The RN of claim 8 , wherein the R-PDCCH transmission begins at a starting OFDM symbol and is to be received on a subset of the OFDM symbols included in the subframe containing the R-PDCCH transmission.
13. The RN of claim 12 , wherein the starting OFDM symbol is not the first OFDM symbol of the subframe including the R-PDCCH transmission.
14. An evolved Node B (eNB) for transmitting a relay physical downlink control channel (R-PDCCH), the eNB comprising:
a processor configured to:
code a plurality of R-PDCCH bits, wherein the plurality of R-PDCCH bits are mapped first in a frequency domain of an orthogonal frequency division multiplexing (OFDM) symbol and second in a time domain across one or more OFDM symbols, and modulate the plurality of R-PDCCH bits to form modulated R-PDCCH bits; and
a transmitter configured to transmit an R-PDCCH transmission to a relay nodes (RN) in subframe configured by the RN as a multimedia broadcast multicast services (MBMS) single frequency network (MBSFN) subframe.