WO2013134951A1

WO2013134951A1 - Methods and apparatus for control signaling resource management

Info

Publication number: WO2013134951A1
Application number: PCT/CN2012/072436
Authority: WO
Inventors: Wei Bai; Jing HAN; Erlin Zeng; Haiming Wang; Chunyan Gao; Shuang TAN; Wei Hong
Original assignee: Renesas Mobile Corporation
Priority date: 2012-03-16
Filing date: 2012-03-16
Publication date: 2013-09-19

Abstract

Systems and techniques for management of uplink control resources. An indicator is sent to a user equipment, indicating whether offloading of uplink control is enabled for the base station. If uplink control is enabled, the user equipment selects resources from among a set of resources including resources associated with at least one secondary cell.

Description

METHODS AND APPARATUS FOR CONTROL

SIGNALING RESOURCE MANAGEMENT

TECHNICAL FIELD:

[0001 ] The present invention relates generally to control signaling in wireless communication networks. More particularly, the invention relates to the use of resources associated with secondary cells for control signaling in cells using carrier aggregation. BACKGROUND:

[0002] Various abbreviations that may be found in the specification and drawing figures are defined as follows:

ACK ACKnowledgement

ARI ACK/NACK Resource Indicator

CA Carrier Aggregation

CC Component Carrier

CSI Channel State Information

DCI DL Control Information

DL Downlink

LTE Long Term Evolution

NACK Negative ACKnowledgement

Pcell Primary Cell

PDCCH Physical Downlink Control Channel

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

RRH Remote Radio Head

Scell Secondary Cell

UE User Equipment

UL Uplink

[0004] The profusion of wireless devices and the demand for services by users of those devices has led to numerous efforts to expand the effective bandwidth available to users. One notable effort along these lines has been carrier aggregation, using the aggregation of primary and secondary component carriers. In a commonly used carrier aggregation scenario, a primary cell (Pcell) is served by a macro eNodeB (eNB) using a first frequency Fl and each of a number of secondary cells (Scells) is served by a remote radio head (RRH) using a second frequency F2. In one scenario, the macro eNB uses Fl to provide wide coverage, while the Scells provide data traffic.

[0005] User devices, also known as user equipments (UEs) must perform significant control signaling, and in many prior-art applications, even UEs that are being served by a Pcell.

SUMMARY:

[0006] According to one embodiment of the invention, an apparatus for controlling a user device comprises at least one processor and memory storing computer program code. The computer program code is arranged to, with the memory and the at least one processor, cause the apparatus to perform actions comprising at least determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device and, if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

[0007] According to another embodiment of the invention, an apparatus for controlling a base station comprises at least one processor and memory storing computer program code. The computer program code is arranged to, with the memory and the at least one processor, cause the apparatus to perform actions comprising at least compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling is enabled for a user device. Compiling the downlink message comprises configuring the downlink message to be sent as part of a control signal.

[0008] According to another embodiment of the invention, a method for controlling a user device comprises arranging at least one processor to cause an apparatus to perform actions comprising at least determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device and, if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

[0009] According to another embodiment of the invention, a method for controlling a user device comprises arranging at least one processor to cause an apparatus to perform actions comprising at least compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling is enabled for a user device. Compiling the downlink message comprises configuring the downlink message to be sent as part of a control signal.

[0010] According to another embodiment of the invention, a computer readable medium for controlling a user device stores a program of instructions. Execution of the program of instructions by a processor arranges the user device to perform actions comprising at least determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device and, if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell. [001 1 ] According to another embodiment of the invention, a computer readable medium for controlling a base station stores a program of instructions. Execution of the program of instructions by a processor arranges the apparatus to perform actions comprising at least compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling is enabled for a user device. Compiling the downlink message comprises configuring the downlink message to be sent as part of a control signal.

[0012] According to another embodiment of the invention, an apparatus for controlling a user device comprises means for determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device and means for, if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

[001 3] According to another embodiment of the invention, an apparatus for controlling a base station comprises means for compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling to a secondary cell is enabled for a user device. Compiling the downlink message comprises configuring the downlink message to be sent as part of a control signal. BRIEF DESCRIPTION OF THE DRAWINGS :

[00 4] Fig. 1 illustrates a wireless network according to an embodiment of the present invention;

[001 5] Fig. 2 illustrates a process according to an embodiment of the present invention; and

[0016] Figs. 3 -5 illustrate details of elements of a wireless network according to one or more embodiments of the present invention.

DETAILED DESCRIPTION:

[001 7] Embodiments of the present invention recognize that control signaling to a Pcell in a carrier aggregation scenario represents a substantial load on the macro eNB serving the Pcell. A macro eNB must serve non-carrier aggregation legacy UEs, as well as UEs with relatively high mobility. Such UEs are not suitable for connection to a remote radio head, and must transmit uplink acknowledgement/negative acknowledgement (ACK/NACK) or channel state information (CSI) to a serving Pcell. In addition, in 3GPP release 10, in a UE configured with a physical uplink control channel and a physical uplink shared channel (PUCCH+PUSCH) uplink ACK/NACK is always transmitted on Pcell PUCCH. Even in cases in which a UE is not configured with PUCCH+PUSCH, PUSCH must be available on an Scell for uplink (UL) ACK/NACK piggyback on PUSCH. But if Pcell PUSCH exists, UL ACK/NACK is to piggyback to Pcell PUSCH, leading to a high Pcell load. In addition, different component carriers for Pcell and Scell communication may be configured with different time division duplex (UL/DL) configurations, and Scells do not provide a PUCCH. HARQ timing is therefore more complex than in the case in which an ACK is allowed to be offloaded to an Scell, even when the downlink is also in a Pcell.

[0018] Therefore, embodiments of the present invention provide mechanisms for offloading uplink control to a Scell. Such mechanisms include signaling to a UE that uplink control offloading is enabled, and further include various mechanisms for determining uplink control resource allocation in instances in which offloading to an Scell is enabled. [0019] Fig. 1 illustrates a wireless network 100 comprising a primary cell, or

Pcell 102, served by a macro eNB 104, and a plurality of secondary cells 106A-106E served by remote radio heads 108A-108C, respectively. The macro eNB 104 may be connected to the remote radio heads (RRHs) 108A-108C by optical fiber connections 1 1 OA- HOC. The wireless network 100 serves a UE 112, which may at different times have a connection to the macro eNB 104 or one of the RRHs 108A-108C.

[0020] The UE 1 12 is able to use resources of the macro eNB 104 or one of the RRHs 108A-108C for uplink control signaling. The UE 1 12 may suitably receive information indicating whether or not offloading UL control signaling to an Scell, that is, using resources associated with an Scell for uplink control signaling, is allowed. If the information indicates that offloading is not allowed, UL resources associated with the Pcell are used. If the information indicates that offloading is allowed, UL resources are chosen according to one or more embodiments of the present invention, with the choice being taken from among a set comprising the Scells, or from among a set comprising the Pcell and the Scells, with the specific choice being made according to specific criteria and prevailing conditions.

[0021] In one or more embodiments of the invention, the UE 1 12 receives an indicator that indicates whether offloading of UL control signaling to Scells is enabled. The indicator may be, in one or more embodiments, an information element in the form of a flag, suitably designated an S Jlag, in UE specific radio resource control signaling. In one or more other embodiments, the S Jlag information element may be include in a downlink control information format. The S Jlag information element may be a single bit,

[0022] If the S Jlag information element indicates that offloading is not enabled, the UE may follow a predefined Pcell PUCCH resource allocation mechanism. For example, one mechanism that may be used is a conventional mechanism defined in 3GPP Release 10, which defines random access (RA) for PUCCH format 3. Four PUCCH resources are assigned through radio resource control (RRC) signaling, and the specific resources to be used are indicated using ARI bits in the PDCCH.

[0023] If the S Jlag information element indicates that offloading is enabled, the UE 112 performs uplink resource allocation according to a mechanism that allows for the use of Scell resources, with the determination of resources to be used being based on specified criteria and conditions. The determination may, for example, include a selection of a specific cell, whose resources are to be used. The selection may alternatively include selection from a set that includes one or more Scells and the Pcell.

[0024] In one or more embodiments of the invention, the ACK/NAC resource indicator (ARI) may be interpreted as a transmit power control command, with the UE 112 selecting a UL control signaling resource based on the following criteria. If at least one PUSCH is scheduled from at least one Scell, UL control signaling is transmitted in the PUSCH resource on the Scell with the smallest cell index or, alternatively, in the PUSCH resource on the Scell with a predefined highest priority. The priority may be predefined using higher layer signaling.

[0025] If no PUSCH is scheduled on any Scell, the UE may interpret the lack of PUSCH scheduling as indicating an inconsistent PDCCH. In one or more alternative embodiments of the invention, UL control signaling may be transmitted in a predefined PUSCH resource, which may designate the Scell with the smallest cell index, or the highest predefined priority. [0026] In one or more embodiments of the invention, the UE may be configured to recognize one or more PUSCH and PUCCH resources as predefined on the Pcell or one or more Scells, and may interpret the ARI as a dynamic indication of one of the predefined resources. The UE 1 12 then selects the resource to be used based on the value of the ARI. As the value of the ARI changes, the UE may change the UL resources being used based on the changing ARI value.

[0027] Fig, 2 illustrates a process 200 of uplink resource selection for a UE according to an embodiment of the present invention. At step 202, an indicator is sent to the UE to indicate whether offloading of UL control resources from a Pcell to an Scell is enabled. The UE may be a UE operating in a carrier aggregation scenario, in which a Pcell communicates using a first frequency and one or more Scells communicate using a second frequency. The indicator may be in the form of a flag included in UE specific radio resource control signaling. Alternatively, the indicator may be in the form of a flag included in the PDCCH DCI format.

[0028] If the indicator indicates that UL control offloading is not enabled, the process proceeds to step 204 and the UE may suitably select one resource from among predefined PUCCH Format 3 resources, based on the value of the ARI, or may perform selection using other mechanisms that do not allow selection of resources associated with an Scell, or dynamic changes of resources.

[0029] If the indicator indicates that UL control offloading is enabled, the process proceeds to step 206 and the UE may suitably perform resource selection using mechanisms that allow for selection of Scell resources. Such mechanisms may include, for example, interpreting the ARI as a transmit power control command and selecting resources for uplink signaling from resources associated with the Scells. Selection may be based in part on whether at least one PUSCH is scheduled from at least one Scell. If at least one PUSCH is scheduled, selection may include selecting an Scell with the smallest cell index or the highest predefined priority. If no PUSCH is scheduled, the UE may interpret the scheduling as representing an inconsistent PDCCH, and may select to perform uplink control signaling using a predefined PUSCH resource on an Scell with the smallest cell index or the highest predefined priority.

[0030] In an alternative configuration according to one or more embodiments of the invention, the one or more PUSCH or PUCCH resources predefined on Pcells or Scells, and the UE may store or otherwise have access to information identifying the resources so predefined. The ARI may be used as an index to the resource to be used, and the UE may change its selection of the resource as the ARI changes.

[0031] The process steps shown in Fig. 2 may also be considered as blocks of a logic flow comprising plurality of coupled logic circuit elements constructed to carry out the associated function(s), or specific result of strings of computer program code stored in a memory.

[0032] Such blocks and the functions they represent are non-limiting examples, and may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

[0033] Such circuit/circuitry embodiments include any of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of circuits and software (and/or firmware), such as: (i) a combination of processor(s) or (ii) portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as an access point, station, mobile phone/UE_; or other suitably configured apparatus, to perform the various functions summarized at Fig. 2 and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" also covers, for example, a baseband integrated circuit or applications processor integrated circuit for a mobile phone/UE, wireless network access point, wireless network station, or a similar integrated circuit in a server, a cellular network device, or other network device.

[0034] Figs. 3, 4, and 5 illustrate further details of the macro eNB 104, the remote radio head (RRH) 108 A, and the UE 1 12 according to one or more embodiments of the present invention. For simplicity, only the remote radio head 108A is illustrated here, but it will be recognized that the remote radio heads 108B and 108C may be similarly configured. The macro eNB 104 may comprise a transmitter 302, receiver 304, radiocontroller 306, and antenna 308. The macro eNB 104 may further comprise a processor 310, memory 312, and storage 314, communicating with one another and with the radiocontroller 306 over a bus 316. The macro eNB 104 may further comprise data 318 and programs 320, suitably residing in storage 314 and transferred to memory 312 as needed for use by the processor 310.

[0035] The RRH 108A may comprise a transmitter 402, receiver 404, radiocontroller 406, and antenna 408. The RRH 108A may further comprise a processor 410, memory 412, and storage 414, communicating with one another and with the radiocontroller 406 over a bus 41 . The RRH 108A may further comprise data 418 and programs 420, suitably residing in storage 414 and transferred to memory 412 as needed for use by the processor 410.

[0036] The UE 500 may comprise a transmitter 802, receiver 504, radiocontroller 8506, and antennas 508. The UE 500 may further comprise a processor 510, memory 512, and storage 514, communicating with one another and with the radiocontroller over a bus 516. The UE 500 may further comprise data 518 and programs 520, suitably residing in storage 514 and transferred to memory 512 as needed for use by the processor 510.

[0037] At least one of the programs 320 in storage 314 of the macro eNB 104 includes a set of program instructions that, when executed by the processor 310, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. The RRH 108A also has software 420 stored in its storage 414 to implement aspects of these teachings as detailed above, and the UE 1 12 similarly has software 520 stored in its storage 514, In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored in storage 314 or memory 312 which is executable by the processor 310 of the macro eNB 102, or by computer software stored in storage 414 or memory 412 executable by the processor 410 of the RRH 108A, or by computer software stored in storage 514 or memory 512 executable by the processor 510 of the UE 112, or by hardware, or by a combination of tangibly stored software and hardware (and tangibly stored firmware). Electronic devices implementing these aspects of the invention need not be the entire devices as depicted at Figs. 3-5, or may be one or more components of same such as the above described tangibly stored software, hardware, firmware and DP, or a system on a chip SOC or an application specific integrated circuit ASIC.

[0038] In general, the various embodiments of the UE 112 can include, but are not limited to personal portable digital devices having wireless communication capabilities, including but not limited to cellular telephones, navigation devices, laptop/palmtop/tablet computers, digital cameras and music devices, and Internet appliances, as well as the machine-to-machine type devices mentioned above.

[0039] Various embodiments of the computer readable memories 312, 412, and 512, and storage 314, 414, and 514 include any data storage technology type which is suitable to the local technical environment, including but not limited to semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, disc memory, flash memory, DRAM, SRAM, EEPROM and the like. Various embodiments of the processors 310, 410, and 510 include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

[0040] While various exemplary embodiments have been described above it should be appreciated that the practice of the invention is not limited to the exemplary embodiments shown and discussed here. Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description.

[0041] Further, some of the various features of the above non-limiting embodiments may be used to advantage without the corresponding use of other described features.

[0042] The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

What is claimed is:

1. An apparatus for controlling a user device comprising:

at least one processor;

memory storing computer program code;

wherein the computer program code is arranged to, with the memory and the at least one processor, cause the apparatus to perform actions comprising at least: determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device; and if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

2. The apparatus of claim 1, where the indicator received by the user device is a flag received in a control signal.

3. The apparatus of claim 1 or 2, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell.

4. The apparatus of any of claims 1-3, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a smallest cell index.

5. The apparatus of any of claims 1-3, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a highest predefined priority.

6. The apparatus of claim 1 or 2, wherein controlling the user device to select resources for use as uplink control comprises selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator.

7. The apparatus of claim 6, wherein selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator comprises selecting one of a physical uplink shared channel and a physical uplink control channel from a set of predefined resources,

8. The apparatus of claim 2, wherein the flag is received by the user device in radio resource control signaling.

9. The apparatus of claim 2, wherein the flag is received by the user device as part of a physical downlink control channel information format.

10. An apparatus for controlling a base station comprising:

at least one processor;

memory storing computer program code;

wherein the computer program code is arranged to, with the memory and the at least one processor, cause the apparatus to perform actions comprising at least: compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling to a secondary cell is enabled for a user device; and

wherein compiling the downlink message comprises configuring the downlink message to be sent as part of a control signal.

11. The apparatus of claim 10, wherein the actions further comprise performing control functions to cause transmission of the indicator to the user device.

12. The apparatus of claim 10 or 1 , wherein the indicator is configured as part of radio resource control signaling.

13. The apparatus of claim 10 or 1 1, wherein the indicator is configured as part of a physical downlink control channel information format.

14. A method for controlling a user device, comprising:

arranging at least one processor to cause an apparatus to perform actions comprising at least:

determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device; and if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

15. The method of claim 14, where the indicator received by the user device is a flag received in a control signal.

16. The method of claim 14 or 15, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell.

17. The method of any of claims 14-16, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a smallest cell index,

18. The method of any of claims 14-16, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a highest predefined priority.

19. The method of claim 14 or 15, wherein controlling the user device to select resources for use as uplink control comprises selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator.

20. The method of claim 19, wherein selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator comprises selecting one of a physical uplink shared channel and a physical uplink control channel from a set of predefined resources.

21. The method of claim 15, wherein the flag is received by the user device in radio resource control signaling.

22. The method of claim 15, wherein the flag is received by the user device as part of a physical downlink control channel information format.

23. A method for controlling a base station comprising:

compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling to a secondary cell is enabled for a user device; and

24. The method of claim 23, wherein the actions further comprises performing control functions to cause transmission of the indicator to the user device.

25. The method of claim 23 or 24, wherein the indicator is configured as part of radio resource control signaling.

26. The method of claim 23 or 24, wherein the indicator is configured as part of a physical downlink control channel information format.

27. A computer readable medium for controlling a user device, storing a program of instructions, execution of which by a processor arranges an apparatus of the user device to perform actions comprising at least:

28. The computer readable medium of claim 27, where the indicator received by the user device is a flag received in a control signal.

29. The computer readable medium of claim 27 or 28, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell.

30. The computer readable medium of claim any of claims 27-29, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a smallest cell index,

31. The computer readable medium of claim any of claims 27-29, wherein controlling the user device to select resources for use as uplink control comprises selecting a physical uplink shared channel associated with a secondary cell having a highest predefined priority.

32. The computer readable medium of claim 27 or 28, wherein controlling the user device to select resources for use as uplink control comprises selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator.

33. The computer readable medium of claim 32, wherein selecting one of a physical uplink shared channel and a physical uplink control channel based on an acknowledgement/negative acknowledgement resource indicator comprises selecting one of a physical uplink shared channel and a physical uplink control channel from a set of predefined resources.

34. The computer readable medium of claim 28, wherein the flag is received by the user device in radio resource control signaling.

35. The computer readable medium of claim 28, wherein the flag is received by the user device as part of a physical downlink control channel information format.

36. A computer readable medium for controlling a base station, storing a program of instructions, execution of which by a processor arranges an apparatus of the user device to perform actions comprising at least:

37. The computer readable medium of claim 36, wherein the actions further comprise performing control functions to cause transmission of the indicator to the user device.

38. The computer readable medium of claim 36, wherein the indicator is configured as part of radio resource control signaling.

39. The computer readable medium of claim 36, wherein the indicator is configured as part of a physical downlink control channel information format.

40. An apparatus for controlling a user device comprising:

means for determining from an indicator received by the user device whether offloading of uplink control information to a secondary cell is enabled for the user device; and

means for, if offloading of uplink control information to a secondary cell is enabled for the user device, controlling the user device to select resources for use as uplink control, wherein at least a portion of the resources considered for selection are associated with a secondary cell.

41 . An apparatus for controlling a base station comprising:

means for compiling a downlink message comprising an indicator to indicate whether offloading of uplink control signaling to a secondary cell is enabled for a user device; and