WO2014019161A1

WO2014019161A1 - Buffer status reporting for time division duplex long term evolution

Info

Publication number: WO2014019161A1
Application number: PCT/CN2012/079484
Authority: WO
Inventors: Haipeng Lei; Yuantao Zhang; Zhi Zhang; Jianchi Zhu
Original assignee: Nokia Corporation
Priority date: 2012-08-01
Filing date: 2012-08-01
Publication date: 2014-02-06

Abstract

Communication systems may benefit from fast buffer status reporting. For example, fast buffer status reporting may be relevant to third generation partnership project (3GPP) long term evolution advanced (LTE-Advanced) technology beyond release 11 (Rel-11). More specifically, fast buffer status reporting may be application to LTE time division duplex (TDD) and may provide further enhancement for traffic adaptation and uplink-downlink (UL-DL) interference management. A method may include detennining an uplink control channel resource to use for signaling a buffer status report. The method may also include signaling the buffer status report on a physical uplink control channel.

Description

BUFFER STATUS REPORTING FOR TIME DIVISION DUPLEX LONG TERM EVOLUTION

BACKGROUND:

Field:

[0001] Communication systems may benefit from fast buffer status reporting. For example, fast buffer status reporting may be relevant to third generation partnership project (3 GPP) long term evolution advanced (LTE- Advanced) technology beyond release 11 (Rel-11). More specifically, fast buffer status reporting may be application to LTE time division duplex (TDD) and may provide further enhancement for traffic adaptation and uplink-downlink (UL-DL) interference management.

Description of the Related Art:

[0002] Currently, 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 may provide between 40% and 90% DL subframes. Current mechanism for adapting UL-DL allocation is based on the system information change procedure with 640ms period. The concrete TDD UL/DL configuration is semi-statically informed by SIB-1 signaling.

[0003] Dynamic TDD UL/DL reconfiguration is a feature for various communication systems, which permit dynamic TDD UL/DL reconfiguration in a TDD system to match uplink and downlink traffic variation.

[0004] There may be high performance gain in term of cell average packet tliroughput when TDD reconfiguration period is set to 10ms compared to fixed TDD UL/DL configurations. For example, faster TDD UL/DL reconfiguration may provide better performance, especially in case of low or medium cell traffic load. To be specific, dynamic TDD UL/DL configuration with a 10ms switching scale may outperform configurations with 200ms or 640ms switching scales.

[0005] Regarding the TDD uplmk-downlink reconfiguration scheme with 10ms switching scale, TDD UL/DL configuration is switched every 10ms. In detail, at the start of each switching period, the eNB selects the most appropriate DL-UL subframe ratio based on the relative instantaneous amount of total downlink and uplink traffic waiting for the scheduling in the eNB. In the simulation, eNB is usually assumed to always ideally know this instantaneous traffic amount of DL and UL available in the cell without any delay and error.

[0006] However, in fact, eNB may only ideally know the traffic amount of DL waiting for scheduling, since the DL buffer is terminated at eNB side. Regarding the UL traffic, since it is generated at UE side, the UE may report this UL amount available to eNB in order to request enough resources to transmit this UL traffic. In LTE, this UE behavior is called buffer status reporting. Throughout this description, buffer status reporting is used as one example of this behavior, although other types of related behavior are not excluded.

[0007] The buffer status report (BSR) conventionally may be a control element of medium access control (MAC) layer, which is used to report the amount of data available in a UE logic buffer for eNB UL scheduling. The BSR may conventionally be transmitted only on PUSCH and may be terminated at MAC layer, specifically in the node where PUSCH is received. The BSR may be transinitted either periodically or given conditions at the UE being fulfilled. Since BSR is transmitted on PUSCH, an UL grant is conventionally always needed to schedule a PUSCH for BSR transmission.

[0008] Figure 2 illustrates current LTE uplink scheduling procedures. In detail, when a UE has uplink data available in a UE logic buffer, it may need to request uplink resources for data transmission. The UE may send the scheduling request (SR) by PUCCH format 1 or physical random access channel (PRACH) for the contention-based uplink resource request, if certain conditions for the SR are fulfilled. According to scheduling policy, the eNB may allocate some PUSCH resources for sending BSR by means of a UL grant to the UE. Then, the UE may transmit the amount of data available in a logic buffer on a scheduled PUSCH to the eNB for UL resources requesting, together with a very limited amount of UL traffic. After receiving this BSR, the eNB may allocate corresponding UL resources by means of an UL grant to the UE for data transmission, taking the uplink radio condition between the UE and the eNB into account. After that, the UE may transmit uplink data and may receive the corresponding ACK/NACK feedback in a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH) or UL grant contained in PDCCH.

[0009] However, if this feature of dynamic TDD UL/DL reconfiguration is directly implemented conventionally in Pico cell, Femto cell, LTE-Hi cell even in Macro cell, it may bring a TDD timing problem, such as DL/UL HARQ timing, PUSCH transmission timing, as well as UL-DL interference between the different transmission directions on some subframes. From the point of BSR transmission's view, this TDD timing problem may impact BSR reporting, leading to further delay due to PUSCH timing change, lower reliability due to UL-DL interference, and so on.

[0010] Figure 3 illustrates a PUSCH tiniing problem in the case of dynamic TDD UL/DL reconfiguration. One example is shown in Figure 3, in the case of TDD UL/DL configuration 1. If UE receives a UL grant for BSR transmission in DL subframe 9, it may transmit BSR on corresponding PUSCH in UL subframe 3 in the next radio frame according to currently specified LTE PUSCH transmission timing rules. However, if the current TDD UL/DL configuration is switched to TDD UL/DL configuration 2, to adapt to the traffic fluctuation, then subframe 3 in the next radio frame will be a DL subframe. Thus, the UE cannot transmit BSR in subframe 3 and may need to find another uplink subframe. Hence, further delay may be introduced for BSR reporting.

[0011] Therefore, considering at least 4ms delay for each UL grant, the whole UL scheduling procedure may be complicated and lengthy, especially in DL-heavy TDD UL/DL configurations. The UE may not timely transmit this BSR information to the eNB, especially in case of DL-heavy TDD UL/DL configuration or UL-heavy traffic flows. Thus, the current BSR reporting mechanism may not adapt to the fast TDD UL/DL reconfiguration with 10ms switching scale. Furthermore, in dynamic TDD UL/DL reconfiguration, the change of TDD PUSCH timing may introduce further delay to BSR transmission. This may degrade the system performance and limit benefits from dynamic TDD UL/DL reconfiguration for traffic adaptation.

SUMMARY:

[0012] A method, according to certain embodiments, includes detennining an uplink control channel resource to use for signaling a buffer status report. The method also includes signaling the buffer status report on a physical uplink control channel.

[0013] A method, in certain embodiments, includes signaling a downlink transmission. The method also includes detennining a position of a buffer status report responsive to the downlink transmission.

[0014] According to certain embodiments, 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 deteraiine an uplink control channel resource to use for signaling a buffer status report. 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 signal the buffer status report on a physical uplink control channel.

[0015] In certain embodiments, 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 signal a downlink transmission. 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 detennine a position of a buffer status report responsive to the downlink transmission.

[0016] An apparatus, according to certain embodiments, includes detennining means for detenriining an uplink control channel resource to use for signaling a buffer status report. The apparatus also includes signaling means for signaling the buffer status report on a physical uplink control channel.

[0017] An apparatus, in certain embodiments, includes signaling means for signaling a downlink transmission. The apparatus also includes deterrnining means for determining a position of a buffer status report responsive to the downlink transmission.

[0018] A non-transitory computer-readable medium is, in certain embodiments, encoded with instructions that, when executed in hardware, perform a process.

[0019] A non-transitory computer-readable medium is, according to certain embodiments, encoded with instructions that, when executed in hardware, perform a process.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0020] For proper understanding of the invention, reference should be made to the accompanying drawings, wherein:

[0021] Figure 1 illustrates a current set of seven kinds of TDD UL/DL configurations.

[0022] Figure 2 illustrates current LTE uplink scheduling procedures.

[0023] Figure 3 illustrates a PUSCH timing problem in the case of dynamic

TDD UL/DL reconfiguration.

[0024] Figure 4 illustrates a buffer status report transmitted in UpPTS in case of ACK/NACK on UL subframe 2.

[0025] Figure 5 illustrates a buffer status report transmitted in UpPTS in the case of a single OFDM symbol, according to certain embodiments. [0026] Figure 6 illustrates a buffer status report transmitted in UpPTS in the case of a pair of OFDM symbols, according to certain embodiments.

[0027] Figure 7 illustrates a method according to certain embodiments.

[0028] Figure 8 illustrates another method according to certain embodiments.

[0029] Figure 9 illustrates a system according to certain embodiments.

DETAILED DESCRIPTION:

[0030] Certain embodiments provide a fast buffer status report (BSR) transmission scheme in case of a dynamic time division duplex (TDD) uplink/downlink (UL/DL) reconfiguration mode. For example, a buffer status report may be directly carried on a physical uplink control channel (PUCCH), for example in a physical uplink control channel format 3. The particular PUCCH resource of a four high layer signaled resource to be used for this buffer status report may be configured by radio resource control (RRC) signaling or may be predefined with a fixed resource index.

[0031] The PUCCH format 3 may include several information bits to indicate the amount of uplink (UL) data available in a user equipment (UE) logic buffer. In this discussion, although a user equipment (UE) is provided as an example, other communication devices, such as relay nodes, are also applicable. The particular number of information bits in an implementation may depend on the requirements of granularity. For example, more bits may be used to provide a higher level of granularity, or a smaller number of bits may be used to provide coarser granularity.

[0032] When acknowledgment/negative acknowledgment (ACK/NACK) bits corresponding to a physical downlink shared channel (PDSCH) or a physical downlink control channel (PDCCH) indicating a downlink (DL) semi persistent scheduling (SPS) release are transmitted with the BSR in the same subframe, BSR reporting may be moved to an uplink pilot time slot (UpPTS) in a nearest special subframe. [0033] The number of orthogonal frequency division multiplexing (OFDM) symbols of UpPTS may be 1 or 2. Thus, there may be at least two cases for the BSR in UpPTS.

[0034] In a first case, the number of OFDM symbols of UpPTS is 1. There may be no room for DM-RS, due to the direct inserting of DM-RS in time domain based on the modulation structure of single carrier frequency division multiple access (SC-FDMA) in uplink. In this case, BSR may be carried in the same PRB index with the PRB carrying ACK/NACK bits in another subframe. Thus, the demodulation reference signal (DM-RS) of the PUCCH carrying ACK/NACK bits may also be used for eNB to demodulate the modulated BSR symbols. On the other hand, considering the feature of intra- subframe frequency hopping of PUCCH, BSR may be transmitted in two PRBs with the following PRB index: where m depends on the format of

aforementioned PUCCH carrying ACK/NACK bits. The modulated BSR symbols may be divided into two parts and respectively transmitted in the two

PRBs or repeated in two PRBs for frequency diversity gain.

[0035] In a second case, the number of OFDM symbols of UpPTS is 2. In this case, the BSR may be transmitted with one DM-RS for eNode B (eNB) demodulation. This DM-RS may be directly inserted in the time domain with the same PRB index with the BSR symbols. Alternatively, if no DM-RS is introduced, the BSR may be transmitted with the same structure as in the first case.

[0036] At the eNB side, after PDSCH or PDCCH indicating DL SPS release is transmitted, the eNB may determine which UL subframe and which PUCCH resource are to be used to feedback ACK/NACK. The determination may be based on predefined DL HARQ timing. If the subframe is used for ACK/NACK feedback, then there may be no BSR reporting in this subframe. The BSR may be transmitted in the UpPTS of the nearest special subframe with the same PRB index, with the PUCCH carrying ACK/NACK. Thus, misunderstanding regarding the positions of BSR and ACK/NACK between eNB and UE may be avoided.

[0037] According to certain embodiments, therefore, the UL traffic amount information may be quickly reported to the eNB for TDD UL/DL configuration determination. Thus, the data in UE buffer may be transmitted more timely and efficiently. Furthermore, a scheduling request (SR) with PUCCH format 1 may be removed or omitted when dynamic TDD UL/DL reconfiguration with fast BSR reporting is used.

[0038] As discussed above, TDD UL/DL configuration may be dynamically changed within a variety of configurations, for example, to match the instantaneous traffic variation in uplink and downlink as well as possible. Therefore, according to the seven configurations approach described above, only subframes 0, 1, 5, 6 are definitely used for downlink transmission and subframe 2 is definitely used for uplink transmission. The other subframes, 3, 4, 7, 8 and 9, are flexible subframes which maybe used for downlink or uplink. The actual transmission direction may be dependent on the TDD UL/DL configuration selected by eNB.

[0039] As also described above, if there are data available in a UE buffer, conventionally the UE may send a scheduling request first and then wait for the UL grant. The UE cannot send a buffer status report until it receives the UL grant for buffer status report transmission. Given that conventionally there is at least 4ms of delay between the eNB and the UE, the whole BSR transmission procedure may require a minimum of 8ms after SR transmission. If the delay of SR transmission is considered, the whole procedure may be lengthy, especially in DL-heavy TDD UL/DL configurations due to very limited opportunity for UL transmission. Therefore, the current BSR reporting mechanism may not adapt to the fast TDD UL/DL reconfiguration with 10ms switching scale. Furthermore, in dynamic TDD UL/DL reconfiguration, the change of TDD PUSCH timing may introduce further delay to BSR transmission. This may degrade system performance and limit benefits from dynamic TDD UL/DL reconfiguration for traffic adaptation.

[0040] In order to, for example, speed up the BSR reporting for UE working in dynamic TDD UL/DL reconfiguration mode, the UE may transmit BSR on

PUCCH format 3, if no ACK/NACK is feedback in the same subframe, or otherwise on UpPTS. Such an approach may improve the system performance.

[0041] The following is an example of a procedure that illustrates certain embodiments. First, if there are data available in the UE's buffer, the UE may transmit the BSR to indicate the amount of UL data waiting for scheduling in the buffer. The number of infomiation bits of BSR may be, for example, 6 or 8 which depends on the requirements of granularity.

[0042] Next, if there is no ACK/NACK feedback in the current subframe, the UE may directly transmit BSR information on PUCCH format 3. Since no ACK/NACK resource mdicator (ARI) is indicated, the used PUCCH resource may be predefined with a fixed ARI. For example, PUCCH resource with ARI=0 may be used for BSR transmission.

[0043] When ACK/NACK bits corresponding to PDSCH or PDCCH indicating DL SPS release are transmitted in the current subframe, BSR reporting may be moved to the UpPTS in the nearest special subframe to maintain the property of single-carrier in uplink.

[0044] For example, in case of TDD UL/DL configuration 5, the UE may want to transmit BSR in uplink subframe 2 and may find out the UE also needs to transmit ACK/NACK feedback corresponding to scheduled DL subframe from 9 to 8 in uplink subframe 2. If the UE moves the BSR transmission to subframe 2 in the next radio frame, the BSR reports would be delayed 10ms. Moreover, if there are also ACK/NACK feedback in this subframe, UE may have to further delay BSR transmission. [0045] BSR transmission is moved to the UpPTS in special subframe 1, as shown in Figure 4 as an example. This approach may help to maintain single-carrier property in uplink and speed up BSR reporting. Thus, Figure 4 illustrates a buffer status report transmitted in UpPTS in case of ACK/NACK on UL subframe 2.

[0046] When the number of OFDM symbols of UpPTS is one, the BSR may be earned in the same PRB index, with the PRB carrying ACK/NACK bits in another subframe, in order to reuse the DM-RS of the PUCCH carrying ACK/NACK bits for eNB to demodulate the BSR symbols. This approach may be used because there is no room for DM-RS due to the direct inserting of DM-RS in time domain based on the modulation structure of SC-FDMA in uplink. Figure 5, therefore, illustrates a buffer status report transmitted in UpPTS in the case of a single OFDM symbol, according to certain embodiments.

[0047] Considering the feature of intra-subframe frequency hopping of PUCCH, the BSR may be transmitted in two PRBs with the following PRB index: where m depends on the format of

aforementioned PUCCH carrying ACK/NACK bits.

[0048] Regarding the modulation of BSR information bits, one example is to use 8 bits for indicating the amount of data in UE buffer. These 8 bits may be modulated to 4 symbols by QPSK, d0, dl, d2 and d3, and then divided into two parts. In order to, for example, obtain frequency diversity gain, dO dl may be carried on the PRB with index of «_{PRB 0} and d2 d3 on the PRB with index of "PRB, I · Allowing for the case that several UEs' PUCCH may be configured in one PRB, BSR transmission in UpPTS may employ multiplexing among different UEs. For PUCCH format 3, the channel may be configured to support up to five UEs on one PRB by orthogonal cover code (OCC). The typical user number multiplexing on one PRB may be tliree, in order to lower the mutual interference. Therefore, a PRB carrying a BSR may support up to three users' BSR transmissions. These UEs maybe multiplexing in frequency division multiplexing (FDM), for example a comb structure, or in code division multiplexing (CDM).

[0049] Alternatively, all four symbols may be carried on one PRB. Thus, different UEs' BSR transmissions may be assigned to different PRBs in order to simplify the multiplexing issue.

[0050] When the number of OFDM symbols of UpPTS is two, the BSR may be transmitted with one DM-RS for eNB demodulation. This DM-RS may be directly inserted in time domain with the same PRB index with the BSR symbols. Figure 6 illustrates a buffer status report transmitted in UpPTS in the case of a pair of OFDM symbols, according to certain embodiments.

[0051] Alternatively, if no DM-RS is introduced, the BSR may be transmitted with the same structure as shown in Figure 5.

[0052] Additionally, since UpPTS may always be used for uplink transmission, the BSR may always be transmitted only in UpPTS. In this case, the number of OFDM symbols of UpPTS may be required to be two, so that one DM-RS may be inserted, as shown in Figure 6.

[0053] At the eNB side, after PDSCH or PDCCH indicating DL SPS release is transmitted, according to predefined DL HARQ timing, eNB may know which UL subframe and which PUCCH resource are to be used to feedback ACK/NACK. If the subframe is used for ACK/NACK feedback, then there is no BSR reporting in this subframe. Thus the BSR may be transmitted in the UpPTS of the nearest special subframe with the same PRB index with the PUCCH carrying ACK/NACK. Accordingly, there may be no misunderstanding on the positions of BSR and ACK/NACK between eNB and UE.

[0054] Regarding the short random access channel (RACH) in UpPTS, since BSR in UpPTS is only in the region of PUCCH, collisions may be avoided between BSR and short RACH. Moreover, SRS in UpPTS is configurable and consequently collision between SRS and BSR may also be avoided.

[0055] Furthermore, if the UpPTS for BSR transmission is not immediately followed by or following the subframe for ACK/NACK transmission, due to very strong channel correlation in time domain due to low mobility, DM-RS of PUCCH format may also be used for demodulating BSR.

[0056] Certain embodiments, therefore, may benefit from dynamic TDD UL/DL reconfiguration. Moreover, certain embodiments may provide for fast BSR reporting for eNB to determine TDD UL/DL configuration, and may provide further improved system performance.

[0057] Figure 7 illustrates a method according to certain embodiments. The method of Figure 7 maybe performed by, for example, a user equipment. The method may include, at 710, detennining an uplink control channel resource to use for signaling a buffer status report. The method may also include, at 720, signaling the buffer status report on a physical uplink control channel, for example in a PUCCH format 3.

[0058] The detennining may include at least one of, at 712, receiving radio resource control signaling or, at 714, referring to a predefined fixed resource index.

[0059] When acknowledgment or negative acknowledgment bits are to be transmitted in a same subframe as the buffer status report, the method may include, at 730, reporting the buffer status report in an uplink pilot time slot of a nearest special subframe. The acknowledgment or negative acknowledgment bits may correspond to a physical downlink shared channel or correspond to a physical downlink control channel indicating downlink semi persistent scheduling release.

[0060] When the number of orthogonal frequency division multiplexed symbols of the uplink pilot time slot is one, modulated buffer status report symbols may be divided, at 740, into two physical resource blocks or may be repeated, at 745, into two physical resource blocks.

[0061] When the number of orthogonal frequency division multiplexed symbols of the uplink pilot time slot is two, the buffer status report may be signaled, at 750, with one demodulation reference signal.

[0062] Figure 8 illustrates another method according to certain embodiments. The method of Figure 8 may be performed by, for example, a base station or eNode B. The method may include, at 810, signaling a downlink transmission. The downlink transmission may be a physical downlink shared channel or a physical downlink control channel indicating downlink semi persistent scheduling release. The method may also include, at 820, determining a position of a buffer status report responsive to the downlink transmission. The determining may be based on a predefined downlink hybrid automatic repeat request timing.

[0063] Figure 9 illustrates a system according to certain embodiments of the invention. In one embodiment, a system may include several devices, such as, for example, access point 910, which may be an eNode B, and UE 920. The system may include more than one UE 920 and more than one access point 910, although only one of each is shown for the purposes of illustration. The system may also involve only at least two UEs 920 or only at least two access points 910. Each of these devices may include at least one processor, respectively indicated as 914 and 924. At least one memory may be provided in each device, and indicated as 915 and 925, respectively. The memory may include computer program instructions or computer code contained therein. One or more transceiver 916 and 926 may be provided, and each device may also include an antenna, respectively illustrated as 917 and 927. Although only one antenna each is shown, many antennas and multiple antenna elements may be provided to each of the devices. Other configurations of these devices, for example, may be provided. For example, access point 910 and UE 920 may be additionally configured for wired communication, in addition to wireless communication, and in such a case antennas 917 and 927 may illustrate any form of communication hardware, without being limited to merely an antenna.

[0064] Transceivers 916 and 926 may each, independently, be a transmitter, a receiver, or both a transmitter and a receiver, or a unit or device that may be configured both for transmission and reception.

[0065] Processors 914 and 924 may 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 may be implemented as a single controller, or a plurality of controllers or processors.

[0066] Memories 915 and 925 may 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 maybe used. The memories may be combined on a single integrated circuit as the processor, or may be separate therefrom. Furthermore, the computer program instructions may be stored in the memory and which may be processed by the processors may be any suitable form of computer program code, for example, a compiled or interpreted computer program written in any suitable programming language.

[0067] The memory and the computer program instructions may be configured, with the processor for the particular device, to cause a hardware apparatus such as access point 910 and UE 920, to perform any of the processes described above (see, for example, Figures 4-8). Therefore, in certain embodiments, a non-transitory computer-readable medium may be encoded with computer instructions that, when executed in hardware, may perform a process such as one of the processes described herein. Alternatively, certain embodiments of the invention may be perfonned entirely in hardware.

[0068] Furthermore, although Figure 9 illustrates a system including an access point 910 and a UE 920, embodiments of the invention may be applicable to other configurations, and configurations involving additional elements, as illustrated and discussed herein. For example, multiple user equipment devices and multiple access points may be present as shown in Figure 1, or other nodes providing similar functionality, such as relays which may receive data from an access point and forward the data to a UE and may implement both functionality of the UE and functionality of the access point.

[0069] One having ordinary skill in the art will readily understand that the invention as discussed above may be practiced with steps in a different order, and/or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the invention has been described based upon these preferred embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention. In order to determine the metes and bounds of the invention, therefore, reference should be made to the appended claims.

[0070] Glossary

[0071] LTE Long term evolution

[0072] LAN Local area network

[0073] AP Access point

[0074] DAI Downlink assignment index

[0075] DCI Downlink control information

[0076] ARI ACK/NACK resource indicator

[0077] ABSF Absolute blank subframe

[0078]DL Downlink

[0079] eNB evolved Node B

[0080]PDCCH Physical downlink control chamiel

[0081]PDSCH Physical downlink shared channel

[0082] PUCCH Physical uplink control channel [0083]PUSCH Physical uplink shared channel

[0084] RRC Radio resource control

[0085] UE User equipment

[0086]UL Uplink

Claims

What is claimed is:

1. A method, comprising:

determining an uplink control channel resource to use for signaling a buffer status report; and

signaling the buffer status report on a physical uplink control channel.

2. The method of claim 1, wherein the determining comprises at least one of receiving radio resource control signaling or referring to a predefined fixed resource index.

3. The method of claim 1, further comprising:

in case acknowledgment or negative acknowledgment bits are to be transmitted in a same subframe as the buffer status report, reporting the buffer status report in an uplink pilot time slot of a nearest special subframe.

4. The method of claim 3, wherein the acknowledgment or negative acknowledgment bits correspond to a physical downlink shared channel or corresponds to a physical downlink control channel indicating downlink semi persistent scheduling release.

5. The method of claim 3, wherein, when a number of orthogonal frequency division multiplexing symbols of the uplink pilot time slot is one, the buffer status report is to be transmitted in same physical resource block index with the physical resource block carrying the acknowledgement or negative acknowledgement bits.

6. The method of claim 5, wherein modulated buffer status report symbols are divided into two parts and transmitted in two physical resource blocks or repeated into the two physical resource blocks, wherein the two physical resource blocks are with the physical resource block indexes: where m depends on the format of the

physical uplink control channel carrying the acknowledgement or negative acknowledgement bits.

7. The method of claim 3, wherein, when a number of orthogonal frequency division multiplexing symbols of the uplink pilot time slot is two, the buffer status report is signaled with one demodulation reference signal.

8. A method, comprising:

signaling a downlink transmission; and

determining a position of a buffer status report responsive to the downlink transmission.

9. The method of claim 8, wherein the determining is based on a predefined downlink hybrid automatic repeat request timing.

10. The method of claim 8, wherein the downlink transmission comprises a physical downlink shared channel or a physical downlink control channel indicating downlink semi persistent scheduling release.

11. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein 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 determine an uplink control channel resource to use for signaling a buffer status report; and

signal the buffer status report on a physical uplink control channel.

12. The apparatus of claim 11, wherein 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 the resource by at least one of receiving radio resource control signaling or referring to a predefined fixed resource index.

13. The apparatus of claim 11, wherein 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, in case acknowledgment or negative acknowledgment bits are to be transmitted in a same subframe as the buffer status report, report the buffer status report in an uplink pilot time slot of a nearest special subframe.

14. The apparatus of claim 13, wherein the acknowledgment or negative acknowledgment bits correspond to a physical downlink shared channel or corresponds to a physical downlink control channel indicating downlink semi persistent scheduling release.

15. The apparatus of claim 13, wherein 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, when a number of orthogonal frequency division multiplexing symbols of the uplink pilot time slot is one, transmit the buffer status report in same physical resource block index with the physical resource block carrying the acknowledgement or negative acknowledgement.

16. The apparatus of claim 15, wherein modulated buffer status report symbols are divided into two parts and transmitted in two physical resource blocks or repeated into the two physical resource blocks, wherein the two physical resource blocks are with the physical resource block indexes: where m depends on the format of the

17. The apparatus of claim 13, wherein 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, when a number of orthogonal frequency division multiplexed symbols of the uplink pilot time slot is two, signal the buffer status report with one demodulation reference signal.

18. The apparatus of claim 1 1, wherein the buffer status report is signaled in a physical uplink control channel format 3.

19. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein 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 signal a downlink transmission; and

determine a position of a buffer status report responsive to the downlink transmission.

20. The apparatus of claim 19, wherein 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 detemiine the position based on a predefined downlink hybrid automatic repeat request timing.

21. The apparatus of claim 19, wherein the downlink transmission comprises a physical downlink shared channel or a physical downlink control channel indicating downlink semi persistent scheduling release.

22, An apparatus, comprising:

determining means for determining an uplink control channel resource to use for signaling a buffer status report; and

signaling means for signaling the buffer status report on a physical uplink control channel.

23. The apparatus of claim 22, further comprising:

reporting means for, in case acknowledgment or negative acknowledgment bits are to be transmitted in a same subframe as the buffer status report, reporting the buffer status report in a uplink pilot time slot of a nearest special subframe.

24. An apparatus, comprising:

signaling means for signaling a downlink transmission; and

determining means for detennining a position of a buffer status report responsive to the downlink transmission.

25. The apparatus of claim 24, wherein the detennining is based on a predefined downlink hybrid automatic repeat request tmiing.

26. A non-transitory computer-readable medium encoded with instructions that, when executed in hardware, perform a process, the process comprising the method of any of claims 1-10.