Allocating a control channel for carrier aggregation

• US 8,843,168 B2
• Filed: 10/18/2011
• Issued: 09/23/2014
• Est. Priority Date: 05/03/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Wang, Ping
• Primary Examiner(s): Safaipour, Bobbak
• Application Number:
  US13/275,608
• Publication Number:
  US 20120034945A1
• Time in Patent Office: 1,071 Days
• Field of Search: 455/522, 455/422, 455/434, 455/507, 370/328, 370/329, 370/252, 370/241
• US Class Current: 455/509
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0016 Time-frequency-code
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 28/12 using signalling between network elements
• CPC Class Codes: H04W 36/22 for handling the traffic
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/52 : based on load
• CPC Class Codes: H04W 76/27 : Transitions between radio resource control [RRC] states
• CPC Class Codes: H04W 8/04 : Registration at HLR or HSS [Home Subscriber Server]
• CPC Class Codes: Y02D 30/00 : Reducing energy consumption in communication networks
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

Methods for allocating a physical downlink control channel (PDCCH) to reduce a number of PDCCH candidates in a search space for carrier aggregation on a user equipment (UE) are disclosed. The method comprises the step of selecting a control channel element (CCE) aggregation level for a PDCCH allocation for each of a plurality of user equipments (UEs) at an evolved NodeB (eNB). The operation of identifying a transmission mode for each of a plurality of component carriers (CCs) associated with the PDCCH at the eNB follows. The next operation of the method is assigning each CC'"'"'s downlink control information (DCI) into CCEs in a PDCCH search space in the PDCCH starting at a CCE location based on the CC'"'"'s transmission mode and the CCE aggregation level for the UE receiving the CC.

Claims

1. A method for allocating a control channel to reduce a number of control channel candidates in a search space for carrier aggregation in a mobile communication system, comprising:

selecting a control channel element (CCE) aggregation level for a control information allocation for a user equipment (UE) at an evolved NodeB (eNB);

identifying a value selected from at least one of a transmission mode of each of a plurality of component carriers (CCs), a carrier index (CI) in a downlink control information (DCI) format for of each of the plurality of CCs, and a DCI size of each of the plurality of CC'"'"'s control information determined by the transmission mode, wherein each CC is associated with a physical downlink control channel (PDCCH); and

assigning, at the eNB, each CC'"'"'s control information into CCEs in a search space in the control channel starting at a CCE location based on a value identified for a CC and the CCE aggregation level for the UE receiving the CC.

2. The method of claim 1, wherein the value is received from Radio Resource Control (RRC) signaling related to each CC.

3. The method of claim 1, further comprising:

receiving the control channel at the UE;

searching for a selected CC'"'"'s control information in a search space by identifying the starting CCE location based on the value identified for the CC;

decoding each control channel candidate in the search space beginning at the starting CCE location until a validly decoded control channel candidate is decoded; and

obtaining the selected CC'"'"'s control information from the validly decoded control channel candidate.

4. A method for allocating a physical downlink control channel (PDCCH) to reduce a number of PDCCH candidates in a search space for carrier aggregation on a user equipment (UE), comprising:

selecting a control channel element (CCE) aggregation level for a PDCCH allocation for each of a plurality of user equipments (UEs) at an evolved NodeB (eNB);

identifying a transmission mode for each of a plurality of component carriers (CCs) associated with the PDCCH at the eNB; and

assigning each CC'"'"'s downlink control information (DCI) into CCEs in a PDCCH search space in the PDCCH at a CCE starting location that is selected based on the CC'"'"'s transmission mode and the CCE aggregation level for the UE receiving the CC.

5. The method of claim 4, further comprising:

receiving the PDCCH at the UE;

searching for a selected CC'"'"'s DCI in the PDCCH search space by identifying the starting CCE location based on the selected CC'"'"'s transmission mode and the CCE aggregation level for the UE receiving the selected CC;

decoding each PDCCH candidate in the PDCCH search space beginning at the CCE starting location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.

6. The method of claim 5, wherein decoding each PDCCH candidate in the PDCCH search space further comprises:

incrementing to a next PDCCH candidate by a number of CCEs determined by the CCE aggregation level.

7. The method of claim 5, further comprising:

receiving the selected CC at the UE, wherein the selected CC'"'"'s DCI is included on another CC'"'"'s PDCCH.

8. The method of claim 5, further comprising determining the selected CC'"'"'s transmission mode via radio resource control (RRC) signaling prior to receiving the PDCCH at the UE.

9. The method of claim 5, further comprising recursively searching the PDCCH search space at a different CCE aggregation level until a validly decoded PDCCH candidate is decoded.

10. The method of claim 4, wherein assigning each CC'"'"'s DCI into CCEs further comprises:

assigning the CCEs of the CCs with a first transmission mode into a first transmission mode search space with a first transmission mode starting CCE location; and

assigning the CCEs of the CCs with a second transmission mode into a second transmission mode search space with a second transmission mode starting CCE location that differs from the first transmission mode starting CCE location.

11. The method of claim 4, wherein assigning each CC'"'"'s DCI into CCEs further comprises:

assigning the CCEs of CCs having a same transmission mode as a PDCCH CC into a same search space with a same starting CCE location; and

assigning the CCEs of CCs having a different transmission mode as the PDCCH CC into a plurality of different search spaces corresponding to the different transmission mode CC'"'"'s transmission mode, wherein the PDCCH CC is the CC transmitting the PDCCH.

12. The method of claim 4, further comprising:

identifying a carrier index (CI) in a DCI format for each of the plurality of CCs associated with the PDCCH at the eNB;

determining a starting CCE location for each assignment in the PDCCH search space based on the CC'"'"'s CI.

13. The method of claim 12, wherein assigning each CC'"'"'s DCI into CCEs further comprises:

assigning the CCEs of the CCs with a first transmission mode and a first CI into a first combined transmission mode and CI search space with a first combined transmission mode and CI starting CCE location; and

assigning the CCEs of the CCs with a second transmission mode and a second CI into a second combined transmission mode and CI search space with a second combined transmission mode and CI starting CCE location that differs from the first combined transmission mode and CI starting CCE location, wherein either the first transmission mode differs from the second transmission mode or the first CI differs from the second CI.

14. The method of claim 12, further comprising:

identifying a DCI size of the CC'"'"'s control information determined by the transmission mode for each of the plurality of CCs associated with the PDCCH at the eNB; and

determining a starting CCE location for each assignment in the PDCCH search space based on the CC'"'"'s DCI size.

15. The method of claim 14, wherein assigning each CC'"'"'s DCI into CCEs further comprises:

assigning the CCEs of the CCs with a first transmission mode, a first CI, and a first DCI size into a first combined transmission mode, CI, and DCI size search space with a first combined transmission mode, CI, and DCI size starting CCE location; and

assigning the CCEs of the CCs with a second transmission mode, a second CI, and a second DCI size into a second combined transmission mode, CI, and DCI size search space with a second combined transmission mode, CI, and DCI size starting CCE location that differs from the first combined transmission mode, CI, and DCI size starting CCE location, wherein the first transmission mode differs from the second transmission mode, the first CI differs from the second CI, or the first DCI size differs from the second DCI size.

16. The method of claim 4, wherein identifying the transmission mode for each of the plurality of CCs further comprises:

receiving via radio resource control (RRC) signaling a transmission mode for each of the plurality of CCs associated with the PDCCH.

17. The method of claim 4, further comprising:

identifying a cell radio network temporary identifier (C-RNTI) for each UE associated with the PDCCH at the eNB; and

determining a starting CCE location for each assignment in the PDCCH search space using the C-RNTI.

18. The method of claim 4, further comprising scheduling the PDCCH downlink resource assignments, uplink resource grants, or uplink power control commands for a CC.

19. A computer program product, comprising a non-transitory computer usable medium having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement a method for allocating a physical downlink control channel (PDCCH) to reduce a number of PDCCH candidates in a search space for carrier aggregation on an evolved NodeB (eNB) comprising:

selecting a control channel element (CCE) aggregation level for a PDCCH allocation for a user equipment (UE);

identifying a transmission mode for each of a plurality of component carriers (CCs) associated with the PDCCH; and

assigning each CC'"'"'s downlink control information (DCI) into CCEs in the PDCCH at a CCE starting location based on each CC'"'"'s transmission mode and the CCE aggregation level for the UE receiving the CC.

20. A computer program product, comprising a non-transitory computer usable medium having a computer readable program code embodied therein, the computer readable program code adapted to be executed to implement a method for searching a reduced number of physical downlink control channel (PDCCH) candidates in a search space for carrier aggregation on a user equipment (UE) comprising:

receiving a PDCCH at the UE;

searching for a selected component carrier'"'"'s (CC'"'"'s) downlink control information (DCI) in a PDCCH search space by identifying a starting control channel element (CCE) location based on the selected CC'"'"'s transmission mode and a CCE aggregation level for the UE receiving the selected CC;

decoding each PDCCH candidate in the PDCCH search space beginning at a CCE starting location until a validly decoded PDCCH candidate is decoded; and

obtaining the selected CC'"'"'s DCI from the validly decoded PDCCH candidate.