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 abovementioned 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 wireless transmit/receive unit (WTRU), the method comprising:
receiving a transmission associated with a physical downlink control channel (PDCCH) from a base station, wherein the transmission associated with the PDCCH is received in a set of control channel elements (CCEs), wherein the transmission associated with the PDCCH is received on a set of orthogonal frequency division multiplexing (OFDM) symbols, wherein the set of CCEs is mapped first along a frequency domain of an OFDM symbol and mapped second in a time domain across the set of OFDM symbols;
demodulating the transmission associated with the PDCCH to determine demodulated PDCCH bits; and
decoding the demodulated PDCCH bits.
2. The method as in claim 1 , wherein the demodulated PDCCH bits are mapped to a number of resource blocks (RBs) and an indication of the number of RBs is received via a radio resource control (RRC) message.
3. The method as in claim 1 , wherein the transmission associated with the PDCCH begins at a starting OFDM symbol that is not the first OFDM symbol of a time period.
4. The method of claim 1 , wherein the demodulated PDCCH bits are decoded immediately after receiving resource blocks (RBs) associated with a symbol.
5. The method of claim 1 , wherein the PDCCH occupies resource elements (REs) that otherwise would be used for a physical downlink shared channel (PDSCH).
6. The method of claim 1 , wherein the PDCCH carries an uplink (UL) grant.
7. A wireless transmit/receive unit (WTRU) comprising:
a processor configured to:
receive a transmission associated with a physical downlink control channel (PDCCH) from a base station, wherein the transmission associated with the PDCCH is received in a set of control channel elements (CCEs), wherein the transmission associated with the PDCCH is received on a set of orthogonal frequency division multiplexing (OFDM) symbols, wherein the set of CCEs is mapped first along a frequency domain of an OFDM symbol and mapped second in a time domain across the set of OFDM symbols;
demodulate the transmission associated with the PDCCH to determine demodulated PDCCH bits; and
decode the demodulated PDCCH bits.
8. The WTRU of claim 7 , wherein the demodulated PDCCH bits are mapped to a number of resource blocks (RBs) and an indication of the number of RBs is received via a radio resource control (RRC) message.
9. The WTRU of claim 7 , wherein the transmission associated with the PDCCH begins at a starting OFDM symbol that is not the first OFDM symbol of a time period.
10. The WTRU of claim 7 , wherein the demodulated PDCCH bits are decoded immediately after receiving resource blocks (RBs) associated with a symbol.
11. The WTRU of claim 7 , wherein PDCCH occupies resource elements (REs) that otherwise would be used for a physical downlink shared channel (PDSCH).
12. The WTRU of claim 7 , wherein the PDCCH carries an uplink (UL) grant.
13. A base station comprising:
a processor configured to:
encode a plurality of physical downlink control channel (PDCCH) bits to generate a plurality of encoded PDCCH bits;
modulate the plurality of encoded PDCCH bits into a plurality of modulated PDCCH bits;
map the modulated PDCCH bits to a set of control channel elements (CCEs), wherein the CCEs are mapped first along a frequency domain of an orthogonal frequency division multiplexing (OFDM) symbol and mapped second in a time domain across one or more OFDM symbols; and
a transmitter configured to transmit the modulated PDCCH bits in a transmission associated with the PDCCH to a wireless transmit/receive unit (WTRU).
14. The base station of claim 13 , wherein the modulated PDCCH bits are mapped to a number of resource blocks (RBs) and the number of RBs are indicated to the WTRU via a radio resource control (RRC) message.
15. The base station of claim 13 , wherein the transmission associated with the PDCCH begins at a starting OFDM symbol that is not the first OFDM symbol of a time period.
16. The base station of claim 13 , wherein the PDCCH occupies resource elements (REs) that otherwise would be used for a physical downlink shared channel (PDSCH).
17. The base station of claim 13 , wherein the PDCCH carries an uplink (UL) grant.