SCHEDULING

TECHNICAL FIELD:

[0001 ] The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs, and more specifically relate to signaling multiple resource assignments or schedules into a single downlink control information message. BACKGROUND:

[0002] Abbreviations used in this description and/or in the referenced drawings are defined below following the Detailed Description section.

[0003] Relevant to carrier aggregation in the LTE radio access technology, the future release 11 is expected to support inter-band carrier aggregation for at least TDD downlink, to include the case where the different bands have different UL/DL configurations. For more specifics see documents RP-091440 by Nokia entitled CARRIER AGGREGATION FOR LTE [3 GPP TSG RAN#46; Sanya, P.R. China; 1-4 December 2009] and RP-110451 by Nokia and Nokia Siemens Networks entitled LTE CARRIER AGGREGATION ENHANCEMENTS [3 GPP TSG RAN#51; Kansas City, USA; 15-18 March 2011], In general the non-limiting examples below assume the primary component carrier or PCell is scheduling the secondary component carrier or SCell. The UL/DL configuration tells whether a given subframe is DL or UL as shown by example at Figures 1 A-B.

[0004] It is also agreed in the 3 GPP that cross carrier scheduling will be used for inter-band TDD carrier aggregation where the different bands/carriers are using different TDD DL/UL configurations. But the different UL/DL configurations mean that there will be some DL subframes in a scheduled cell (SCell in the examples) that could not be scheduled since the scheduling cell (PCell in these examples) is an UL subframe. [0005] Figure 1A illustrates the above issue. The PCell on which the DCI (PDCCH which schedules radio resources) is operating with UL/DL configuration #0 while the SCell on which the radio resources are scheduled is operating with UL/DL configuration #4. As shown at Figure 1 A subframe #4, #7, #8, #9 cannot be scheduled in the SCell using cross carrier scheduling from the PCell since those subframes for the PCell configuration #0 are all UL subframes. The switching subframes denoted as "S" in Figures 1A-B are downlink.

[0006] Time domain bundling scheduling provides a promising way to avoid wasting radio resources due to inefficient scheduling which is inherent in the Figure 1A example. In this technique multiple DL subframes may be scheduled by one PDCCH.

Time domain bundling being actively considered for reducing the PDCCH overhead; see for example document Rl-112427 by NTT and Docomo entitled VIEWS ON

CARRIER AGGREGATION ENHANCEMENT FOR REL- 1 1 [3 GPP TSG RAN WG#66; Athens, Greece; 22-26 August 2011].

[0007] Figure 1 A illustrates one example of how scheduling bundling can work for the Figure 1A example so that subframe #4, #7, #8 and #9 in the SCell can be scheduled from the PCell. Specifically, a PDCCH in subframe #1 on the PDCCH can schedule subframe #1 and #4 in the SCell, while a PDCCH in subframe #6 of the PCell could schedule subframe #6, #7, #8, #9 in the SCell. In this manner all the DL subframes in the scheduled SCell could be scheduled by the PCell in which the scheduling information is sent, even though the TDD configurations on these two cells are different.

[0008] Additionally, for the future Release 1 1 of the LTE system there is a need to limit the PDCCH overhead since that load is already increasing due to support for multi-user MIMO. Time domain bundling scheduling could also aid with this goal since multiple DL subframes are scheduled by only one PDCCH.

[0009] What is needed in the art is a way to implement time domain scheduling bundling for the cross-carrier scheduling environment. There are some proposals in 3 GPP on this general topic; see for example documents Rl-112427 noted above; Rl-113038 by New Postcomm entitled PDCCH BUNDLING ANALYSIS FOR DOWNLINK

CONTROL SIGNALING ENHANCEMENT; and Rl-113381 by Qualcomm ENTITLED

SUPPORT OF CROSS-CARRIER CONTROL FOR CARRIER AGGREGATION OF DIFFERENT TDD UL-DL CONFIGURATIONS ON DIFFERENT BANDS [both from 3 GPP TSG RAN WGl#66bis; Zhuhai, China; 10-14 October 2011]. These all lack details for how to implement signaling to enable scheduling bundling to resolve the problem noted by example at Figure 1 A.

SUMMARY:

[0010] In a first exemplary embodiment of the invention there is a method comprising: indicating in a downlink control information message which N radio resources on a second component carrier are being scheduled, where N is an integer greater than one; and sending the downlink control information message on a first com onent carrier to schedule the plurality of radio resources.

[0011] In a second exemplary embodiment of the invention there is an apparatus comprising at least one processor and at least one memory storing a computer program. In this embodiment the at least one memory with the computer program is configured with the at least one processor to cause the apparatus to at least: indicate in a downlink control information message which N radio resources on a second component carrier are being scheduled, where N is an integer greater than one; and send the downlink control information message on a first component carrier to schedule the plurality of radio resources.

[0012] In a third exemplary embodiment of the invention there is a computer readable memory tangibly storing a computer program executable by at least one processor for causing an apparatus to: indicate in a downlink control information message which N radio resources on a second component carrier are being scheduled, where N is an integer greater than one; and send the downlink control information message on a first component carrier to schedule the plurality of radio resources. [0013] In a fourth exemplary embodiment of these teachings there is an apparatus comprising: scheduling means for indicating in a downlink control information message which N radio resources on a second component carrier are being scheduled, where N is an integer greater than one; and sending means for sending the downlink control information message on a first component carrier to schedule the plurality of radio resources.

[0014] These and other embodiments and aspects are detailed below with particularity. BRIEF DESCRIPTION OF THE DRAWINGS:

[0015] Figure 1A is a schematic timing diagram showing scheduling inefficiencies when a PCell on which scheduling allocations are sent is using a different DL UL configuration than a SCell on which the scheduled resources lie, and is an exemplary environment in which these teachings can be practiced to advantage,

[0016] Figure I B is similar to Figure 1 A but showing scheduling bundling to resolve the inefficiencies shown at Figure I B.

[0017] Figure 2A is a table illustrating bit values and exemplary meanings for signaling associated with scheduling bundling according to an example for one embodiment of these teachings.

[0018] Figure 2B is a table similar to Figure 2 A but according to an example for a different embodiment of these teachings.

[0019] Figure 3 is a timing diagram similar to Figure 1 B but further showing results of different offset values signaled to different user equipments according to an exemplary embodiment of these teachings. [0020] Figure 4 is a timing diagram similar to Figure IB but illustrating how the value N for the maximum number of downlink subframes that are bundled may be implicitly signaled according to an exemplary embodiment of these teachings. [0021] Figure 5 is a logic flow diagram that illustrates from the perspective of the network/eNB the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with an exemplary embodiment of this invention.

[0022] Figure 6 is a simplified block diagram of a UE and an eNB which are exemplary electronic devices suitable for use in practicing the exemplary embodiments of the invention.

DETAILED DESCRIPTION:

[0023] The following examples are in the specific context of the LTE/LTE-Advanced systems (for example, Release 1 1 and later) but these teachings are more broadly applicable to any wireless radio system which employs cross carrier scheduling from one frequency band to another frequency band, even if there is no mis-alignment of DL subframes. These examples consider only a single UE but it will be understood the description applies for all such UEs being scheduled for radio resources according to the teachings described for one UE.

[0024] These teachings provide embodiments for signaling bundling scheduling in the time domain for the case at least in which the PCell on which the scheduling is sent is using a different UL/DL subframe configuration than the SCell on which the radio resources are scheduled.

[0025] First some assumptions and terminology. One assumption is that a single PDCCH could schedule multiple DL subframes. We define a time domain bundling window by the integer variable N, meaning N continuous DL subframes are scheduled by one PDCCH signaling. Another assumption is that for inter-band TDD carrier aggregation there are two different UL DL subframe configurations in use in the two relevant cells PCell and SCell. But note the scheduling bundling signaling used herein can also be used when the UL/DL subframe configurations are the same. For convenience in this description, the term consistent subframe is defined as a subframe for which the TDD configurations on both carriers have the same transmission direction DL or UL. The term overlapped subframe is defined as a subframe for which the TDD configurations on the two different carriers have different transmission direction, For example, in Figure IB subframe #4, #6, #7, #8 and #9 are overlapped subframes while all the others are consistent subframes,

[0026] Now are described different aspects of the signaling design of the DCI, or more particularly the PDCCH in these examples, to implement schedule bundling according to these teachings. As noted above the size of the bundling window is N. According to a first aspect of these teachings there are a number ceil (log2(N) ) of bits that are added to the PDCCH. In an alternative embodiment the number of added bits is N. In either embodiment the eNB scheduler may have flexibility to change the size N of the bundling window, or the size of the bundling window may be fixed (for example, by a published technical standard for the wireless system). These added bits indicate which DL subframe is scheduled.

[0027] Consider for these two embodiments the case where N~4, meaning a single PDCCH signaling on the PCell can schedule up to four DL subframes on the SCell. In the first alternative above then two bits are added to the PDCCH to indicate which DL subframe is scheduled [Ceil (Log2(4))=2], The table at Figure 2A illustrates one set of meanings for different values of these two bits for indicting any of the four DL subframes in the SCell. In this alternative each value of the bit pair indicates whether one, two, three or four subframes are being scheduled.

[0028] The table at Figure 2B illustrates an example of four of the different bit values and their meaning for the case where N bits are added to the PDCCH to indicate which DL subframe(s) are being scheduled. The larger number of bits in this alternative gives a bit greater flexibility than the alternative of Figure 2A. For example the bit value 0101 for the Figure 2B embodiment can indicate two DL subframes which are being scheduled, the subframe of the PDCCH and the second subframe after then PDCCH, which the Figure 2A embodiment cannot do unless also the first subframe after the PDCCH is also scheduled.

[0029] A second aspect of these teachings is signaling to indicate for each subframe being scheduled whether it is for a new transmission or for a retransmission. In conventional LTE there is a single bit termed an NDI which indicates whether the resource being allocated is for a new transmission or for a re-transmission (for example, in response to a negative acknowledgement of the original/new transmission). According to this aspect of the invention the NDI of the PDCCH is also extended to N bits total. This may be considered as a size N bitmap to indicate for each of the subframes in the bundling window whether the scheduled subframe is to carry a new transmission or a re-transmission.

[0030] This extension of the NDI is to enable independent re-transmission of different DL subframes. For example if N=4, then there will be a four-bit bitmap for NDI so that each DL subframe will have one NDI bit to indicate whether the transmission in that scheduled subframe is an initial transmission or a re-transmission. For the case in which the system does not allow bundling of new and re-transmissions, this expansion of the NDI is not necessary. [0031] The following three aspects of the invention concern higher layer signaling for how to configure the cell for bundled scheduling. In a third aspect of these teachings the time domain scheduling bundling is explicitly configured by higher layer signaling, or alternatively is implicitly determined by pre-defined rules. Explicit signaling needs no further explanation; the UE can be signaled via RRC signaling such as when attaching to the cell, or when the SCell is activated for it, or the UE can learn TD scheduling bundling is in use from system information or the master information block.

[0032] For the alternative of this aspect in which the bundled scheduling is implicitly configured by a pre-defined rule, such a relevant wireless standard might state that for inter-band TDD carrier aggregation with different TDD configurations between the PCell and the SCell, for those consistent DL subframes that are followed by an overlapped subframe, time domain bundling scheduling is enabled. By example, subframes #1 and #6 in Figure IB are the only such a consistent DL subframes in that figure.

[0033] There is a possibility that the PDCCH load would become unbalanced. Using Figure IB as an example, in a congested radio environment there would quite a lot of traffic scheduled by the PDCCHs in subframe #1 and #6 as compared to the non-bundle scheduling done by the PDCCHs in subframes #0 and #5. The fourth aspect of these teachings is to mitigate such an imbalance. [0034] In this fourth aspect there is configured by network higher layers, such as via RRC layer signaling, a starting point offset for different UEs as is shown by example at Figure 3. In this aspect the network configures the different UE's with a specific offset which the network and the UE will use to determine which DL subframe in which to send a PDCCH to that UE. By example the network will signal a number of bits ceil (Log2 N)) bits, with different values to the different UEs, to indicate the per-UE offset. So for example if N=4, then two bits would be used to indicate that a given UE's offset is 0, 1, 2, or 3.

[0035] Consider an example implementation of this fourth aspect. Assume the offset is scheduling _off set in the equation below, and so for a specific FDD UE identified as i, the location for the PDCCH of the time domain bundling scheduling could be determined as:

Mod (CURRENT_TTI, N) = scheduling_offset, where

CURRENT_TTI=SFN*10+subframe

[0036] Then the network will configure different offset value for the different UEs, enabling the network to better distribute the PDCCH load in the time domain. Consider Figure 3 as an example of this. As with previous examples N=4, and in this case there are four UEs with offsets as follows: UE1 is given offset=0, UE2 is given offset=l , UE3 is given offset-2 and UE4 is given offset=3. The location of the PDCCH for each of these four UEs is shown at Figure 3. The PDCCH for each of the four UEs is in a different subframe: UE1 gets its PDCCH in subframe #0; UE2 gets its PDCCH in subframe #1 ; UE3 gets its PDCCH in subframe #2; and UE4 gets its PDCCH in subframe #3. Since the bundling window is N=4 subframes then in this case there is also a better distribution in the time domain of the subframes being scheduled as compared to if all UEs had their PDCCH in the same PCell subframe. A greater offset difference among the different UEs would distribute those scheduled resources a bit more in the time domain.

[0037] The fifth aspect of these teachings concern the value for N; it is also either explicitly configured by higher layers or in another embodiment is implicitly determined by a predefined rule such as may be stipulated in a wireless standard. The value of N is the size of the bundling window, the maximum number of DL subframes that could be scheduled by one PDCCH. For example, the value of N is in one embodiment predefined in the specification; in another embodiment it is explicitly configured by higher layer signaling such as RRC signaling; and in still another embodiment the value of N is implicitly configured depending on TDD configuration on the scheduling cell PCell in combination with the TDD configuration on the other cell/SCell.

[0038] As one example for how the value for N may be implicitly determined from the TDD configuration on the scheduling cell/PCell in combination with the TDD configurations on the other cell/SCell, the rule may set the value for N as equal to the DL subframe number from the current scheduling subframe to the next consistent DL subframe. Figure 4 gives a more specific example of this. TDD configuration #0 (on the PCell) is carrier aggregated with TDD configuration #4 (on the SCell), and the SCell is configured to be scheduled by that PCell. The N value for a PDCCH in subframe #1 is N=2, since in total there are two DL subframes on the SCell from the current scheduling subframe to the next consistent DL subframe. Similarly, the N value for subframe #6 is N=4. [0039] Embodiments of the invention detailed above provide certain technical effects such as for example it is a design with reasonable signaling bits for time domain bundling scheduling. Additionally these teachings enable independent re-transmission for different DL subframes for time domain bundling scheduling, and also provide functionality for PDCCH load balancing for time domain bundling scheduling.

[0040] Now are detailed with reference to Figure 5 further particular exemplary embodiments from the perspective of the network/eNB, Figure 5 may be performed by the whole eNB, or by one or several components thereof such as a modem. At block 502 the network indicates in a downlink control information DCI message which N radio resources on a second component carrier are being scheduled, where N is an integer greater than one. Then at block 504 the network sends the downlink control information message on a first component carrier to schedule the plurality of radio resources. In the above examples the first component carrier is the PCell and the second component carrier is the SCell.

[0041] Further portions of Figure 5 represent several of the specific but non-limiting embodiments detailed above. Block 506 provides that the N radio resources are indicated in the DCI message by a total of either N bits or ceil(log2(N)) bits. Block 508 provides the 3. The method according to claim 1 , in which the downlink control information message further comprises an indication for each of the N radio resources whether data in the respective radio resource is new data or re-transmitted data.

[0042] Block 510 summarizes the embodiment above in which the first and second component carriers have different uplink/downlink subframe configurations. Block 512 provides that the DCI message is sent in a subframe indicated by a user-equipment specific offset which is specific for a user equipment to which the which N radio resources are allocated by the downlink control information message. In the examples above it was also detailed sending to user equipment in RRC signaling an indication of the offset.

[0043] And finally at block 514 the value for N is in one embodiment explicitly configured via radio resource control signaling or alternatively is implicit based on TDD configurations for the first and the second component carriers. [0044] The logic flow diagram of Figure 5 may be considered to illustrate the operation of a method, and a result of execution of a computer program stored in a computer readable memory, and a specific manner in which components of an electronic device are configured to cause that electronic device to operate. The various blocks shown in Figure 5 may also be considered as a 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.

[0045] 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.

[0046] Reference is now made to Figure 8 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 8 an eNB 22 is adapted for communication over a wireless link 21 with an apparatus, such as a mobile terminal or UE 20. The eNB 22 may be any access node (including frequency selective repeaters) of any wireless network such as LTE, LTE-A, GSM, GERAN, WCDMA, and the like. The operator network of which the eNB 22 is a part may also include a network control element such as a mobility management entity MME and/or serving gateway SGW 24 or radio network controller RNC which provides connectivity with further networks (e.g., a publicly switched telephone network and/or a data communications network/Internet) . [0047] The UE 20 includes processing means such as at least one data processor (DP) 20A, storing means such as at least one computer-readable memory (MEM) 20B which tangibly stores at least one computer program (PROG) 20C or other set of executable instructions, communicating means such as a transmitter TX 20D and a receiver RX 20E for bidirectional wireless communications with the eNB 22 via one or more antennas 20F. Also stored in the MEM 20B at reference number 20G are the rules for how to recognize and interpret the signaling related to the schedule bundling as detailed further in the non-limiting examples presented above.

[0048] The eNB 22 also includes processing means such as at least one data processor (DP) 22A, storing means such as at least one computer-readable memory (MEM) 22B that tangibly stores at least one computer program (PROG) 22C or other set of executable instructions, and communicating means such as a transmitter TX 22D and a receiver RX 22E for bidirectional wireless communications with the UE 20 via one or more antennas 22F. The eNB 22 stores at block 22G similar rules for how to configure, and how to construct and send the signaling related to the schedule bundling as detailed in the above non-limiting examples.

[0049] While not particularly illustrated for the UE 20 or eNB 22, those devices are also assumed to include as part of their wireless communicating means a modem and/or a chipset which may or may not be inbuilt onto an RF front end chip within those devices 20, 22 and which also operates utilizing the schedule bundling signaling according to these teachings.

[0050] At least one of the PROGs 20C in the UE 20 is assumed to include a set of program instructions that, when executed by the associated DP 20 A, enable the device to operate in accordance with the exemplary embodiments of this invention, as detailed above. The eNB 22 also has software stored in its MEM 22B to implement certain aspects of these teachings as detailed above for Figure 3. In these regards the exemplary embodiments of this invention may be implemented at least in part by computer software stored on the MEM 20B, 22B which is executable by the DP 20A of the UE 20 and/or by the DP 22A of the eNB 22, 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 Figure 4 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.

[0051 ] In general, the various embodiments of the UE 20 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. [0052] Various embodiments of the computer readable MEMs 20B, 22B 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 DPs 20A, 22A include but are not limited to general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and multi-core processors.

[0053] 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. While the exemplary embodiments have been described above in the context of the LTE and LTE-A system, as noted above the exemplary embodiments of this invention may be used with various other CA-type wireless communication systems.

[0054] 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. 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. [0055] The following abbreviations used in the above description and/or in the drawing figures are defined as follows:

3 GPP third generation partnership project

DCI downlink control information

DL downlink

eNB node B base station in an E-UTRAN system

E-UTRAN evolved UTRAN (LTE)

FDD frequency division duplex

LTE long term evolution (of UTRAN)

IMO multiple-input multiple-output

MU multi user

NDI new data indicator

PDCCH physical downlink control channel

PDSCH physical downlink shared channel

RRC radio resource control

SFN system frame number

TDD time division duplex

UE user equipment

UL uplink

UTRAN universal terrestrial radio access network