Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/20—Control channels or signalling for resource management
  • H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
  • H04W72/044—Wireless resource allocation based on the type of the allocated resource
  • H04W72/0446—Resources in time domain, e.g. slots or frames

Definitions

• LTE long term evolution
• LTE-A long term evolution
• 3GPP third generation partnership project
• LTE-A long term evolution
• TDD time division duplex
• UL uplink
• DL downlink
• LTE TDD allows for asymmetric UL-DL allocations by providing seven different semi-statically configured TDD UL-DL configurations shown in Figure 1. These allocations can provide between 40% and 90% DL subframes.
• the current mechanism for adapting UL-DL allocation is based on the system information change procedure with a 640ms period.
• the concrete TDD UL DL configuration is semi-statically informed by system information block, type 1 (SIB-1) signaling.
• SIB-1 system information block
• the various UL-DL allocations can have either 5 ms or 10 ms switching point periodicity.
• the allocations can include allocations for downlink, D, uplink U, and special S.
• the special subframes can be, for example, a guard period.
• TDD UL DL configuration indication in LTE is currently based on the system information change procedure with a 640 ms period.
• the concrete TDD UL/DL configuration is semi-statically informed by SIB-1 signaling.
• TDD UL/DL reconfiguration there is another mode for dynamic TDD UL/DL reconfiguration called transparent mode.
• UE does not need to know the actual TDD UL/DL configuration and the transmission or receiving on the flexible subframe, for example subframe 3, 4, 7, 8 or 9, is completely dependent on eNB scheduling. In this case, UE will have no behavior unless eNB sends scheduling signaling. However, the UE may not know which subframe can be used for ACK/NAC feedback due to not being aware of a concrete TDD UL/DL configuration.
• TDD reconfiguration period it may be valuable to set a TDD reconfiguration period to be 10ms, as opposed to a longer period such as 200 ms or 640 ms.
• the current semi-static mechanism for TDD UL/DL configuration indication namely via SIB-1 signaling in a period of 640 ms, cannot adapt to fast TDD UL/DL reconfiguration, no matter what TDD reconfiguration switching scale is used: 10ms, 30ms, 200ms or any other scale less than 640ms.
• a method includes mforming a user equipment about a cell-specific flexible time division duplex radio network temporary identifier at cell access stage.
• the method also includes providing a downlink control channel having a cyclic redundancy check scrambled by the identifier.
• the method further includes providing a configuration indicator.
• a method includes determining that a cell supports flexible time division duplex configuration based on a cell-specific flexible time division duplex radio network temporary identifier at a cell access stage. The method also includes decoding downlink control channel with cyclic redundancy check scrambled by the flexible time division duplex radio network temporary identifier.
• An apparatus includes at least one processor and at least one memory including computer program code.
• the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to inform a user equipment about a cell-specific flexible time division duplex radio network temporary identifier at cell access.
• the at least one memory and the computer program code are also configured to, with the at least one processor, cause the apparatus at least to provide a downlink control channel having a cyclic redundancy check scrambled by the identifier.
• the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to provide a configuration indicator.
• An apparatus in certain embodiments, includes at least one processor and at least one memory including computer program code.
• the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to detennine that a cell supports flexible time division duplex configuration based on a cell-specific flexible time division duplex radio network temporary identifier at a cell access stage.
• the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to decode downlink control channel with cyclic redundancy check scrambled by the flexible time division duplex radio network temporary identifier.
• an apparatus includes mforming means for mforming a user equipment about a cell-specific flexible time division duplex radio network temporary identifier at cell access.
• the apparatus also includes control means for providing a downlink control channel having a cyclic redundancy check scrambled by the identifier.
• the apparatus further includes sharing means for providing a configuration indicator.
• an apparatus includes detenriining means for detennining that a cell supports flexible time division duplex configuration based on a cell-specific flexible time division duplex radio network temporary identifier at a cell access stage.
• the apparatus also includes decoding means for decoding downlink control channel with cyclic redundancy check scrambled by the flexible time division duplex radio network temporary identifier.
• a non-transitory computer-readable medium is, according to certain embodiments, encoded with instructions that, when executed in hardware, perform a process.
• the process includes mforming a user equipment about a cell-specific flexible time division duplex radio network temporary identifier at ceil access.
• the process also includes providing a downlink control channel having a cyclic redundancy check scrambled by the identifier.
• the process further includes providing a configuration indicator.
• a non-transitory computer-readable medium is, in certain embodiments, encoded with instructions that, when executed in hardware, perform a process.
• the process includes determining that a cell supports flexible time division duplex configuration based on a cell-specific flexible time division duplex radio network temporary identifier at a cell access stage.
• the process also includes decoding downlink control channel with cyclic redundancy check scrambled by the flexible time division duplex radio network temporary identifier.
• Figure 1 illustrates seven current kinds of TDD UL DL configurations.
• Figure 2 illustrates a method according to certain embodiments.
• Figure 3 illustrates another method according to certain embodiments.
• Figure 4 illustrates a system according to certain embodiments.
• Certain embodiments enhance current time division duplex (TDD) configuration indication mechanisms for fast TDD uplink (UL)/ downlink (DL) reconfiguration and provide new TDD UL/DL configuration indication mechanisms. Moreover, certain embodiments provide for fast and reliable TDD UL/DL configuration indication. For example, certain embodiments provide a fast TDD UL/DL configuration indication mechanism for dynamic TDD UL/DL configuration, which can facilitate quick TDD reconfiguration switching, for example, on a scale of 10 ms ⁇ 30 ms, 200 ms, or any other scale less than 640 ms. In certain embodiments, this is obtained through the use of L2 control.
• the base station, access point or eNode B can inform a dynamic TDD-capable user equipment (UE) of the cell-specific flexible TDD radio network temporary identifier (FlexTDD-RNTI) at the cell access stage.
• UE dynamic TDD-capable user equipment
• FlexTDD-RNTI cell-specific flexible TDD radio network temporary identifier
• Medium access control (MAC) signaling can be used to indicate the cell-specific TDD UL/DL configuration after the TDD UL/DL configuration is determined by e B.
• One physical downlink control channel (PDCCH) with cyclic redundancy check (CRC) scrambled by FlexTDD-R TI can be decoded by all the capable UEs.
• the corresponding physical downlink shared channel (PDSCH) can carry the MAC signaling to indicate the current TDD UL/DL configuration or the TDD UL DL configuration to be used for next radio frame, which may be dependent on eNB configuration.
• the PDCCH with CRC scrambled by FlexTDD-RNTI can be transmitted in DL subframes with a fixed subframe index and with the period configured by eNB.
• a dynamic TDD-capable UE can be configured by higher layers to decode PDCCH with CRC scrambled by FlexTDD-RNTI in DL subframes with fixed subframe index with the period configured by eNB.
• the UE After detecting this radio network temporary identifier (RNTI), the UE can decode the PDCCH and the corresponding PDSCH in the same DL subframe and feed back an acknowledgment (AC )/ negative acknowledgment (NACK) to the eNB for confirmation.
• RNTI radio network temporary identifier
• the UE can feed back ACK to eNB. If UE does not correctly decode this PDSCH then the UE can feed back NACK to eNB. If the UE does not detect this RNTI, the UE can avoid feeding back to the eNB at all.
• physical layer signaling can also be used to indicate the cell-specific TDD UL/DL configuration after the TDD UL/DL configuration is determined by the eNB.
• One physical downlink control channel (PDCCH) with cyclic redundancy check (CRC) scrambled by FlexTDD-RNTI can be decoded by all the capable UEs.
• the PDCCH can contain several bits to indicate the current TDD UL/DL configuration or the TDD UL/DL configuration to be used for next radio frame, which may be dependent on the eNB configuration.
• the PDCCH with CRC scrambled by FlexTDD-RNTI can be transmitted in DL subframes with a fixed subframe index and with a period configured by the eNB.
• a dynamic TDD-capable UE can be configured by higher layers to decode PDCCH with C C scrambled by FlexTDD-RNTI in DL subframes with a fixed subframe index with the period configured by the eNB.
• the UE After detecting this radio network temporary identifier (RNTI), the UE can decode the PDCCH and feed back an acknowledgment (ACK) to the eNB for confirmation.
• ACK acknowledgment
• the eNB After receiving the ACK corresponding to the PDCCH carrying TDD UL/DL configuration indication, the eNB can know the UE has correctly obtained the knowledge of the current TDD UL DL configuration and can schedule the UE in the flexible subframes.
• Certain embodiments therefore, can avoid false alarm issues.
• benefits of dynamic TDD reconfiguration can be achieved.
• a fast and reliable TDD UL/DL configuration indication mechanism can be used for dynamic TDD UL/DL configuration, which can avoid false alarm issues and guarantee the reliability of TDD UL/DL configuration indication.
• a user equipment can initially report its capability of supporting dynamic TDD UL/DL reconfiguration to an eNB.
• the UE can be configured by higher layer signaling to decode PDCCH with CRC scrambled by FlexTDD-RNTI in, for example, DL subframe 0 with eNB configured periodicity, such as 10 ms, 30 ms, or the like.
• the eNB can select the most appropriate TDD UL/DL configuration according to traffic fluctuation in UL and DL. Moreover, the eNB can send MAC signaling to the UE supporting the feature of dynamic TDD UL DL reconfiguration, to indicate the current TDD UL/DL configuration.
• One PDCCH with CRC scrambled by FlexTDD-RNTI can be decoded by all the capable UEs.
• a capable UE After detecting FlexTDD-RNTI, a capable UE can decode the PDCCH and the corresponding PDSCH carrying MAC signaling and feed back ACK/NACK to eNB for corifirmation. For example, as mentioned above, if the UE correctly decodes this PDSCH then UE can feed back ACK to eNB, but if the UE does not correctly decode this PDSCH then the UE can feed back NACK to eNB. On the other hand, the UE does not need to provide any feedback if the UE is not able to detect the RNTI. The UEs that lack the capabilities described herein can simply ignore the PDCCH with CRC scrambled by FlexTDD-RNTI.
• the eNB After receiving the ACK NACK corresponding to the TDD UL/DL configuration indication, the eNB can know the UE has correctly obtained the knowledge of the current TDD UL DL configuration and can schedule the UE in the flexible subframes.
• the TDD UL DL configuration can be indicated by 3 bits indexed from 0 to 6 corresponding to current TDD UL DL configurations 0 to 6. Then these 3 bits can be added in a MAC packet data unit (PDU), together with the MAC header. After that, this MAC packet can be sent to physical layer and transmitted on the PDSCH.
• PDU MAC packet data unit
• the TDD UL/DL configuration can be indicated by 2 bits indexed from 0 to 3 corresponding to TDD UL/DL configuration 0, 1, 2 and 6 or indexed from 0 to 2 corresponding to TDD UL/DL configuration 3, 4 and 5. Then the 2 bits can be added in a MAC packet data unit together with the MAC header and transmitted on PDSCH.
• the PDCCH with downlink control information (DCI) format 1C can be transmitted in common search space and used for very compact scheduling of one PDSCH codeword.
• DCI format 1C in common search space is used to schedule the PDSCH carrying TDD UL/DL configuration in MAC layer.
• DCI format 1C can be transmitted with CRC scrambled by FlexTDD-RNTI. This RNTI can have the same length as the CRC. For example, it can be a pseudo-random sequence of 16 bits length.
• the UE After detecting this DCI with CRC scrambled by FlexTDD-RNTI, the UE can decode the PDCCH and the corresponding PDSCH and feed back ACK/NACK to eNB for confirmation.
• TDD UL/DL configuration indication can be specified in one or more fixed DL subframes, such as subframe 0, 1, 5 or 6.
• the UE can detect this DCI with CRC scrambled by FlexTDD-RNTI in the specified subframe, which may decrease the number of blind detections.
• the UE is assumed to read PDCCH with CRC scrambled by FlexTDD-RNTI in every subframe 0, in order to enable timely change for TDD UL DL configuration.
• the UE does not need to feed back ACK/NACK in order to enable timely changes in this same subframe and reduce the signaling overhead.
• the ACK/NACK feedback may take several ms in a frame. Since the configuration can be informed every 10ms, and can repeatedly contain similar information if the configuration does not change rapidly, it may be acceptable for the UE to miss one detection or for a DRX UE to miss the change information.
• SIB-1 signaling can also be used for TDD UL/DL configuration indication.
• TDD UL/DL configuration 5 can be indicated to legacy UE and eNB can avoid scheduling a legacy UE's uplink transmission in subframe 3, 4, 7, 8 or 9. In this way, backward compatibility can be guaranteed with a predictable amount of UL throughput loss.
• RSRP measurement on flexible subframes can be prohibited.
• the eNB can indicate to the legacy UE that the flexible subframes are configured as almost blank subframe (ABSF).
• Certain embodiments of a flexible TDD UL/DL configuration indication procedure for dynamic TDD can have various components.
• the components can includes PDCCH with CRC scrambled by "FlexTDD-RNTI”; MAC signaling of a UL DL configuration; ACK/NACK feedback for the configuration, which acknowledgment process can be disabled by a base station (BS); and RRC signaling on capable UE access procedure to let capable UE override the TDD UL/DL configuration indicated by the SIB-1 signaling and get knowledge of the "FlexTDD-RNTI" and change period, and the like features described herein.
• BS base station
• certain embodiments involve a combination of features.
• the RRC signaling and MAC signaling may only be visible for a capable UE, and a legacy UE can still follow the SIB1 information.
• a MAC signaling can indicate the cell-specific TDD UL/DL configuration for a capable UE to override the current UL DL configuration indicated from SIB-1.
• the configurations can be directly indicated by different R TIs, or a single RNTI can be used for all configurations.
• the legacy UE cannot read the MAC signaling, and consequently will still follow SIB-1.
• the TDD UL/DL configuration 5, or another DL heavy configuration can be indicated to the legacy UE before the eNB decides to use frequently dynamic UL/DL configuration change.
• the eNB can avoid scheduling a legacy UE's uplink transmission in subframe 3, 4, 7, 8 or 9. In this way, backward compatibility can be accomplished while sacrificing a predetermined amount of uplink throughput.
• FlexTDD-RNTI can be used to indicate to compatible UEs whether a current subframe contains the TDD UL/DL configuration indication signaling.
• the PDCCH with CRC scrambled by FlexTDD-RNTI can be transmitted in DL subframes with fixed subframe index with a period configured by the eNB.
• a flexible ACK/NACK procedure for TDD UL/DL configuration can be used.
• the ACK NACK procedure can be used for TDD configuration indication without inducing significant delay, and the dynamic UL/DL configuration changes can be assumed only for small cell, which will not attach too many UEs, thus creating no blocking due to these feedbacks.
• a simple procedure can be used to avoid the delay of ACK NACK confirmation.
• the FlexTDD-RNTI can be cell-specific.
• one PDCCH with CRC scrambled by FlexTDD-RNTI can be decoded by all the capable UEs.
• a corresponding PDSCH can carry the UL/DL configuration indication, which can also be cell specific.
• a higher layer configuration for capable UE can allow capable UE to decode PDCCH with CRC scrambled by "FlexTDD-RNTI" in DL subframes with fixed subframe index with the period configured by eNB to get the new UL/DL configuration in relevant PDSCH, and then override the DL UL configuration information from SIB-1 signaling.
• the capable UE can get the FlexTDD-RNTI of this cell, and know the fixed subframe and period.
• the fixed subframe can be subframe (SF) #0 and the period can be 10ms.
• the UE may or may not need to feed back the AC /NACK. This procedure can occur in an attach procedure.
• a legacy UE does not need to know the FlexTDD-RNTI, and SIB-1 signaling can still be used for TDD UL/DL configuration indication.
• the eNB can indicate TDD UL/DL configuration 5, or another DL heavy configuration, to the legacy UE before the eNB decides to use frequently dynamic UL DL configuration changes.
• the eNB in such cases, can avoid scheduling a legacy UE's uplink transmission in subframe 3, 4, 7, 8 or 9. As mentioned above, this may provide a balance between backward compatibility and throughput.
• the UL/DL configuration changes may be used, for example, in a small cell that may not attach very many UEs. Thus, no significant blocking due to feedback for the feedback procedure may occur. However, in another implementation the UEs do not need to feed back ACK/NACK.
• Certain embodiments may provide benefit from dynamic TDD UL/DL reconfiguration. Moreover, certain embodiments may provide this benefit without requiring a special PDCCH format. Certain embodiments also permit an explicit TDD UL DL configuration indication for UE. Furthermore, certain embodiments can guarantee the reliability of the TDD UL/DL configuration indication. Moreover, certain embodiments can avoid false alarm due to dynamic TDD UL/DL reconfiguration.
• Figure 2 illustrates a method according to certain embodiments.
• the method of Figure 2 can be performed by, for example, a base station such as an eNode B.
• a method can include, at 210, informing a user equipment about a cell-specific flexible time division duplex radio network temporary identifier at cell access.
• the mforming can include medium access control or higher layer signaling, which also contains the fixed subframe index for configuration indication, period and/or require acknowledgment or not.
• the method can also include, at 220, providing a downlink control channel having a cyclic redundancy check scrambled by the identifier.
• the downlink control channel can be transmitted in downlink subframes with a fixed subframe index and with the period configured by a base station.
• the method can also include, at 225, providing a configuration indicator.
• the method can further, at 230, include providing a downlink shared channel corresponding to the downlink control channel.
• the method can also include, at 235, scheduling the user equipment in flexible subframes in which the transmission direction may change according to the time division duplex uplink-downlink configuration, upon receiving an acknowledgment in response to a configuration provided on the physical downlink shared channel if the cell requires acknowledgement, or directly if the cell does not require acknowledgment.
• a configuration indicator provided by the downlink control channel or its corresponding downlink shared channel can indicate a current time division duplex uplink-downlink configuration, a time division duplex uplink-downlink configuration to be used for a next radio frame, or both.
• the configuration indicator on the downlink control channel can be provided via a new PDCCH format.
• the configuration indicator on the downlink shared channel can be provided by, for example, MAC signaling or punctured bits on fixed position.
• the method can further include, at 240, providing a default configuration using system information block signaling.
• the method additionally include, at 250, avoiding scheduling a device with uplink transmission in subframe 3, 4, 7, 8, or 9 which are used for flexible subframes and thus conflict with the default configuration, when the device does not support flexible time division duplex configuration, for example a legacy device.
• the method can also include, at 260, selecting time division duplex uplink-downlink configuration 5 for a device when the device does not support flexible time division duplex configuration, such as a legacy device.
• the method can further include, at 270, prohibiting reference signal received power measurement on flexible subframes.
• Figure 3 illustrates another method according to certain embodiments.
• the method of Figure 3 may be performed by, for example, a user equipment.
• the method can include, at 305, reporting capability of supporting flexible time division duplex configuration to a base station. In other words, the device can report that it is capable of handling the very dynamic TDD UL/DL configuration approach described above.
• the method can also include, at 310, detennining that a cell supports flexible time division duplex configuration based on a cell-specific flexible time division duplex radio network temporary identifier at a cell access stage.
• the method can further include, at 320, decoding physical downlink control channel with cyclic redundancy check scrambled by the flexible time division duplex radio network temporary identifier.
• the decoding can include decoding the physical downlink control channel in downlink subframes with fixed subframe index with the period configured by a base station.
• the method can additionally include, at 330, decoding a physical downlink shared channel corresponding to the physical downlink control channel.
• the downlink shared channel can indicate a current time division duplex uplirik-downlink configuration or a time division duplex uplirik-downlink configuration to be used for a next radio frame.
• the method can also include, at 340, feeding back an acknowledgment or negative acknowledgment to a base station regarding decoding of the physical downlink control channel.
• the method can additionally, include at 350, feeding back ACK when ACK/NACK. feedback required, or decoding the downlink control channel without acknowledgment, when the cell does not require acknowledgment.
• FIG. 4 illustrates a system according to certain embodiments of the invention.
• a system may include two devices, such as, for example, UE 410 and eNB 420.
• Each of these devices may include at least one processor, respectively indicated as 414 and 424.
• At least one memory is provided in each device, and indicated as 415 and 425, respectively.
• the memory may include computer program instructions or computer code contained therein.
• Transceivers 416 and 426 are provided, and each device may also include an antenna, respectively illustrated as 417 and 427. Other configurations of these devices, for example, may be provided.
• UE 410 and eNB 420 may be configured for wired communication, rather than wireless communication, and in such a case antennas 417 and 427 would illustrate any form of communication hardware, without requiring a conventional antenna.
• Transceivers 416 and 426 can each, independently, be a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that is configured both for transmission and reception.
• Processors 414 and 424 can be embodied by any computational or data processing device, such as a central processing unit (CPU), application specific integrated circuit (ASIC), or comparable device.
• the processors can be implemented as a single controller, or a plurality of controllers or processors.
• Memories 41 and 425 can independently be any suitable storage device, such as a non-transitory computer-readable medium.
• a hard disk drive (HDD), random access memory (RAM), flash memory, or other suitable memory can be used.
• the memories can be combined on a single integrated circuit as the processor, or may be separate therefrom.
• the computer program instructions stored in the memory and which may be processed by the processors can be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language.
• the memory and the computer program instructions can be configured, with the processor for the particular device, to cause a hardware apparatus such as UE 410 and eNB 420, to perform any of the processes described above (see, for example. Figures 2 and 3). Therefore, in certain embodiments, a non-transitory computer-readable medium can be encoded with computer instructions that, when executed in hardware, perform a process such as one of the processes described herein. Alternatively, certain embodiments of the invention can be performed entirely in hardware.
• Figure 4 illustrates a system including a UE and an eNB
• embodiments of the invention may be applicable to other configurations, and configurations involving additional elements, as discussed herein.
• the system can include both users that are capable of flexible TDD reconfiguration and also legacy UEs.
• ABSF Almost blank subframe

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Cited By (13)

Citations (2)

• 2012
  • 2012-05-14 WO PCT/CN2012/075466 patent/WO2013170426A1/fr not_active Ceased

Patent Citations (2)

Non-Patent Citations (2)

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