DL Backhaul Control Channel Design For Relays

• US 20110103292A1
• Filed: 08/12/2010
• Published: 05/05/2011
• Est. Priority Date: 08/14/2009
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Shin, Sung-Hyuk H., Beluri, Mihaela C., Pasad, Kalpendu R., Rudolf, Marian, Haim, John W., Adjakple, Pascal M.
• Granted Patent: US 8,976,806 B2
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 84/047 using dedicated repeater stations
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

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)) formapping 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.

Claims

1. A method for determining relay node. (RN) control channel data comprising:

receiving an orthogonal frequency division multiplexing (OFDM) symbol comprising relay physical downlink control channel (R-PDCCH) data modulated in a time-frequency grid, wherein the R-PDCCH data is first modulated along the frequency domain across the OFDM control symbol;

demodulating the OFDM symbol; and

transmitting R-PDCCH data to a control channel processing unit.

2. The method of claim 1, wherein demodulating the OFDM symbol comprises:

demodulating the OFDM symbol into demodulated bits.

3. The method of claim 2, further comprising:

constructing n vectors of the demodulated bits, wherein n is the number of OFDM symbols;

demarcating an ith vector at a control channel element (CCE) boundary where bits beyond the integer number of the control channel element are considered a part of the following OFDM symbol, wherein the ith vector is equal to the number of bits in the ith OFDM symbol, wherein i is greater than or equal to 1 and less than or equal to n.

4. The method of claim 3, further comprising:

blind decoding over the CCE on a per OFDM symbol basis.

5. The method of claim 2, further comprising:

constructing n vectors of the demodulated bits, wherein n is the number of OFDM symbols;

demarcating an7th vector at a control channel element (CCE) boundary where null bits beyond the integer number of CCEs are discarded, wherein the ith vector is equal to the number of bits in the ith OFDM symbol, wherein i is greater than or equal to 1 and less than or equal to n.

6. The method of claim 5, further comprising:

blind decoding over the CCE on a per OFDM symbol basis.

7. The method of claim 6, further comprising:

performing interleaving and CCE randomization over the span of the OFDM symbol

8. The method of claim 6, wherein blind decoding further comprises:

using a hashing function identical to a device algorithm, for each aggregation level; and

the relay determining a candidate CCE over which to perform the decoding.

9. The method of claim 6, further comprising:

determining that in the /th OFDM symbol a R-PDCCH is not addressed to the RN and continuing to decode over a symbol i+1.

10. A device comprising:

a processor configured to;

receive, from an eNodeB, consecutive first and second OFDM symbolsthat represent a plurality of relay physical downlink control channels (R-PDCCH) that comprises a first R-PDCCH and a second R-PDCCH; and

decode the first R-PDCCH from the first OFDM symbol which is received before the second OFDM symbol.

11. The device of claim 10, wherein the first and second OFDM symbols encode control channel elements that encode the plurality of R-PDCCHs.

12. The device of claim 10, wherein the processor is further configured to ignore the second OFDM symbol if all the monitored R-PDCCHs intended for the device are detected in the first OFDM symbol.

13. The device of claim 10, wherein the first OFDM symbol comprises one or more whole control channel elements and padding.

14. The device of claim 10, wherein the first OFDM symbol comprises one or more whole control channel elements and one partial control channel element.

15. A method comprising:

selecting at least one backhaul control channel, each backhaul control channel having associated a relay;

node specific control information over a plurality of resource blocks (RBs), each RB comprising a known number of sub-carriers in frequency domain, and a known number of Orthogonal Frequency Division Multiplexing (OFDM) symbols in time domain; and

mapping, uniformly, of RBs across the frequency domain.

16. The method of claim 15, further comprising:

selecting the RBs for the backhaul control channel according to;

R_l(i)=└

i.N_l,RB^DL/N<sub>l,MAX—

REL—

RB</sub>┘

+k, where

R_l(i)=RB index for l^th Control OFDM symbol,

i=0,1,2 . . . N<sub>l,MAX—

REL—

RB</sub>−

1

N<sub>l,MAX—

REL—

RB</sub> is the number of RBs reserved for backhaul control channel in the l^th OFDM smybol

N_l,RB^DL=Maximum number of RBs in the l^th OFDM control symbol

k=integer derived from donor evolved Node-B (eNB) cell identity (ID)

where additions are modulo N_l,RB^DL.

17. The method of claim 16, Wherein mapping is performed according to:

using a subsequent OFDM symbol allocated for the backhaul control and continue the mapping;

wrapping around in the same OFDM symbol and populate all available RBs and once all RBs are utilized, continue mapping over the next OFDM symbol from the next RB location given by the R_l(i).

18. The method of claim 16, wherein mapping is performed according to:

using a subsequent OFDM symbol allocated for the backhaul control and continue the mapping;

wrapping around in the same symbol and populate all available RBs and once all RBs are utilized, continue mapping over the next OFDM symbol from RB location given by setting i=0 in the R_l(i).

19. The method of claim 15, further comprising:

determining a backhaul control channel mapping option supported by the network in at least one of a system information broadcast message and radio resource control signaling.

20. The method of claim 15, wherein uniform mapping comprises:

relay-physical control format indicator channel (R-PGFICH) and relay-physical hybrid automatic repeat request (HARQ) indicator channel (R-PHICH) are mapped in only part of the RB.