Power headroom indication for small data transmission

Abstract

An apparatus configured to: receive, from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting; determine the apparatus's PH; select a PRACH resource for a random access preamble, Msg1, transmission based on the received PRACH resource selection configuration; and transmit the Msg1 indicating a PH report to the network node.

Description

POWER HEADROOM INDICATION FOR SMALL DATA TRANSMISSIONTECHNICAL FIELD

[0001] The example and non-limiting embodiments relate generally to wireless communications and, more particularly, methods, apparatuses and computer program products to allow an IoT (Internet of Things) user equipment to indicate its power headroom to the network for SDT (small data transmission).BACKGROUND

[0002] It is known that PH (power headroom) reports are used to support power-aware uplink scheduling which allows the network to efficiently allocate uplink transmission resources. PH denotes the difference between the UE maximum transmit power and the estimated power for uplink transmission.SUMMARY

[0003] The following summary is merely intended to be illustrative. The summary is not intended to limit the scope of the claims.

[0004] In accordance with one aspect, an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to: receive, from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting; determine the apparatus’s PH; select a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; and transmit the Msgl indicating a PH report to the network node.

[0005] In accordance with one aspect, a method comprising: receiving, with a user equipment from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting; determining the user equipment’s PH; selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; and transmitting the Msgl indicating a PH report to the network node.

[0006] In accordance with one aspect, an apparatus comprising: means for receiving, from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting; means for determining the apparatus’s PH; means for selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; and means for transmitting the Msgl indicating a PH report to the network node.

[0007] In accordance with one aspect, a non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing receiving, with a user equipment from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting; causing determining the user equipment’s PH; causing selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; and causing transmitting the Msgl indicating a PH report to the network node.

[0008] In accordance with one aspect, an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to: transmit a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment; receive a random access preamble, Msgl, indicating PH report from the user equipment, determine an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; and transmit a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

[0009] In accordance with one aspect, a method comprising: transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment; receiving a random access preamble, Msgl, indicating PH report from the user equipment; determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; and transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

[0010] In accordance with one aspect, an apparatus comprising: means for transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment; means for receiving a random access preamble, Msgl, indicating PH report from the user equipment; means for determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; and means for transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

[0011] In accordance with one aspect, a non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment; causing receiving a random access preamble, Msgl, indicating PH report from the user equipment; causing determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; and causing transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

[0012] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0014] FIG. 1 is a diagram illustrating SDT procedure to support data transmission in RRC_INACTIVE state as described herein;

[0015] FIG. 2 is a diagram illustrating power headroom reporting in Msgl via RA-SDT as described herein;

[0016] FIG. 3 is a diagram illustrating Msgl power control incorporating power headroom as described herein;DETAILED DESCRIPTION OF EMBODIMENTS

[0017] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:5GC 5G core5 QI 5G QoS IdentifierBSR Buffer Status ReportBWP Bandwidth PartCE Control ElementCE Coverage EnhancementDL DownlinkDMRS Demodulation Reference SignalDTX Discontinuous TransmissionEDT Early Data TransmissionEIRP Effective Isotropic Radiated PowereMBB Enhanced Mobile BroadbandFR1 Frequency Range 1FR2 Frequency Range 2gNB Next generation Node-BIoT Internet of thingsLCG Logical Channel GroupLPWA Low Power Wide AreaLTE-M Long-Term Evolution Machine Type Communication MAC Medium Access ControlMCS Modulation and Coding SchemeMIB Master Information BlockNB-IoT Narrowband Internet of ThingsNR New RadioNW NetworkPBCH Physical Broadcast ChannelPDCCH Physical Downlink Control ChannelPDSCH Physical Downlink Data ChannelPH Power HeadroomPHR Power Headroom ReportPRACH Physical Random Access ChannelQoS Quality of ServiceRACH Random Access ChannelRAR Random Access ResponseRE Resource ElementRedCap Reduced CapabilityRO RACH OccasionRSRP Reference Signal Received PowerRSRP Reference Signal Received QualityRSSI Received Signal Strength IndicatorSDT Small Data TransmissionSFN System Frame NumberSIB System Information BlockSRS Sounding Reference SignalSSB Synchronization Signal BlockTBS Transport Block SizeTTI Transmission Time IntervalUE User EquipmentUL Uplink

[0018] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0019] Some embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the disclosure are shown. Indeed, various embodiments of the disclosure may be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein; rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. As used herein, the terms “data,” “content,” “information,” and similar terms may be used interchangeably to refer to data capable of being transmitted, received and / or stored in accordance with some embodiments of the present disclosure. Thus, use of any such terms should not be taken to limit the spirit and scope of example embodiments of the present disclosure.

[0020] Internet of things (IoT) traffic (e.g. sensor measurement reports, usage reports, location reports, etc.) are generally delay-tolerant. For infrequent data transmission of small packet, Small Data Transmission (SDT) procedure has been defined in 5G New Radio (NR) to support data transmission in RRC_INACTIVE state without having to transition to RRC_CONNECTED state. This can save significant Radio Resource Control (RRC) overhead as well as reduce data transmission latency. In addition, power consumption at the user equipment (UE) is reduced. An example flow diagram of the SDT procedure is shown in FIG. 1.

[0021] For 6G, it is expected that SDT or a similar procedure will be supported. This procedure can be the basis for IoT traffic transmission.

[0022] In NR, power headroom (PH) reports are used to support power- aware Uplink (UL) scheduling. This allows the network to efficiently allocate UL transmission resources. Powerheadroom denotes the difference between the UE maximum transmit power and the estimated power for uplink transmission. In TS 38.133, the power headroom reporting mapping is provided as shown in Table 1. Power headroom reporting can be configured periodically or can be trigger-based (e.g. if the pathloss has changed more than the configured threshold).Table 1. Power headroom report mapping (TS 38.133, Table 10.1.17.1-1)

[0023] Typical IoT data packet size is small, and it is expected that SDT will be the main procedure for UE to send its reports. For instance, in TR 38.913, a 20 byte application packet (corresponding to 105 bytes at the physical layer with uncompressed IP header) was used as a reference for evaluation purpose. If Robust Header Compression (RoHC) header is used, the physical layer packet size can be significantly small (e.g. TCP / IP overhead is 20 bytes for IPv4, 40 bytes for IPv6, but 1-4 bytes for ROHC). As a result, it is expected that IoT data packet can be sent in a single uplink transmission (i.e. Msg3 in SDT procedure).

[0024] However, for the network to efficiently allocate UL resources for Msg3, it needs to know the UE’s uplink channel quality and the UE’s power headroom (i.e. the difference between the UE’s maximum transmit power and the uplink transmit power). The network can estimate the uplinkchannel quality from Msgl (random access preamble). However, it doesn’t know the power headroom. Thus, the network may assign conservative Modulation and Coding Scheme (MCS) value for Msg3 when it could select a more aggressive MCS value if the power headroom is known. Selecting a more conservative MCS value means the UE will consume more uplink resources, thus reducing the network capacity. Therefore, a method is needed to allow IoT UE to indicate its power headroom to the network in Msgl.

[0025] Two schemes are proposed here. Scheme- 1 - UE indicates power headroom (PH) or power headroom range to the network in Msgl. Several options are available: preamble partitioning, PRACH time resource partitioning, and PRACH preamble repetition. Scheme-2 - Msgl transmission power includes PH. Msgl transmission power can be adjusted based on PH, i.e. UE with larger power headroom will transmit with higher power. We will discuss both schemes in detail below.

[0026] Referring now to FIG. 2, this figure shows a block diagram of one possible and nonlimiting example solution (Scheme- 1) in which the examples may be practiced. In Scheme- 1, The network configures PRACH resource selection (210) for PH reporting. After UE determines its PH and selects the appropriate PRACH resource for Msgl transmission (220), UE indicates power headroom (PH) or power headroom range to the network in Msgl (230). Several example embodiments for configuring PRACH are available.

[0027] In a first example embodiment, network partitions the preambles into one or more groups, where each group indicates a range of PH values available at the UE. The PH can be determined at the UE based on Msgl transmission power (i.e. difference between the maximum UE power and the transmission power used on Msgl). UE then selects the preamble group corresponding to its available PH.

[0028] For example, the preambles for SDT can be divided into 3 groups with the following PH indication: Group 1: PH < 10 dB, Group 2: 10 < PH < 20 dB, Group 3: 20 dB < PH. Each group corresponds to a range of measured or determined PH values (in dB) at the UE. The number of preambles within each group is configurable such that the preambles can be partitioned either uniformly or non-uniformly across the different groups.

[0029] In another example, different grouping may be provided for different UE power classes. This can be used e.g. to minimize interference or near-far issue between UE with different maximum transmission power.

[0030] In a further example, the preambles are partitioned into one or more groups, where each group is mapped to a scheduling configuration e.g. Config 1 = (P01, MCS1, NumberOfPRB 1, etc.), Config2 = (P02, MCS2, NumberOfPRB2, etc.), Config3 = (P03, MCS3, NumberOfPRB3, etc.). The UE may then indicate its scheduling preference by transmission of a preamble from the corresponding group.

[0031] In yet another example, a group of preambles may be reserved to indicate that the UE will send the PH report in Msg3 (without SDT transmission). This can be used e.g. by UE with small power headroom.

[0032] In a second example embodiment, network partitions the PRACH time occasions into one or more groups, where each group indicates a range of PH values available at the UE. The PH can be determined at the UE based on Msgl transmission power (i.e. difference between the maximum UE power and the transmission power used on Msgl). UE then selects the preamble group corresponding to its available PH.

[0033] For example, if a PRACH occasion is configured every 10ms at subframe #0, it can be divided into 3 groups with the following PH indication: Group 1 - select PRACH occasion where modulo(SFN,3) = 0 if PH < 10 dB, Group 2 - select PRACH occasion where modulo(SFN,3) = 1 if 10 < PH < 20 dB, Group 3 - select PRACH occasion where modulo(SFN,3) = 2 if 20 < PH.

[0034] In another example, a timing mask may be used to indicate the grouping e.g. {1,2, 3, 1,2, 3,...} can be used to indicate the grouping for each PRACH occasion starting from a reference point (e.g. SFN = 0). This can allow unequal allocation of the groups e.g. { 1,2, 2, 2, 3, 1,2, 2,2,3,... }. This example will increase random access latency for the UE, but loT traffic is delay tolerant so it should not be an issue. If latency is a concern, a group of preambles for SDT without PH indication can be reserved at every PRACH occasion.

[0035] In a third example embodiment, network configures different numbers of PRACH repetitions for different levels of power headroom. For example, the smaller the power headroom, the more the number of repetitions. UE would transmit Msgl with the appropriate number of repetitions to indicate power headroom.

[0036] The network then counts the number of PRACH repetitions a UE used for its preamble transmissions to interpret the PH range for that UE, which requires the network to detect the number of PRACH repetitions.

[0037] In another example, P PRACH_target can be adjusted with the repetitions. UE may adjust PRACH transmission power according to the number of repetitions so that the total PRACH power after repetitions reach the desired target power.

[0038] In a further example, the preamble time-frequency resources used may overlap. gNB then blindly detects the number of repetitions (by trying out different hypotheses of repetitions) in PRACH detection process and get the PHR at Msgl.

[0039] In yet another example, the number of repetitions corresponding to different levels of power headroom are configured to achieve a low probability of incorrect detection. This may require maintaining a significant difference in the number of repetitions corresponding to the adjacent levels. For example: Group 1 - use 4 repetitions if PH < 10 dB, Group 2 - use 8 repetitions if 10 < PH < 20 dB, Group 3 - use 16 repetitions if 20 < PH.

[0040] In a fourth example embodiment, a combination of the example embodiments discussed above, e.g., a combination of preamble partitioning and PRACH time occasion partitioning, may be used.

[0041] For all example embodiments above, the initial partitioning could be a uniform partition (equal PH ranges). Alternatively, historical data (stored by the network) could be used to determine non-uniform initial partitions. For example, clustering is performed on the data points to define the partition thresholds. This would enable fine partitions where more UEs have indicated their PHs andcoarser partitions where fewer UEs have indicated their PHs. Both the number of partitions as well as the thresholds are decided by the network.

[0042] The network may also adjust the preamble partitioning based on the received responses from the UEs.

[0043] The network may initially configure uniform or equal partitions of the PRACH preambles or PRACH occasions. The network may, however, adjust the preamble partitioning or PRACH occasion partitioning based on the received responses from the UEs. For example, if the network detected more PRACH collisions at one group relative to the others, the network may decide to dedicate more preambles / resources to that group and fewer preambles / resources to the other groups. Alternatively, if no or a few preamble transmissions are detected at one group, the network may re-assign some of the preambles / resources of that group to other groups.

[0044] In a fifth example embodiment, a combination of preamble partitioning and PRACH additional frequency (or subcarrier) offset associated to PH may be used. For example, the UE applies subcarrier offsets 0, 12 and 24 respectively for CE levels 0, 1 and 2, and it applies an additional subcarrier offset of PH_SC_Offsetl for PH < 10 dB, PH_SC_Offset2 for 10 < PH < 20 dB, and PH_SC_Offset3 for 20 < PH. The values may be configured by the network.

[0045] In a sixth example embodiment, the partitioning of PRACH resources is carried out in combination with the size of the message the UE anticipates to transmit in Msg3. For example, the group partitioning of the preambles is based on the product of the UE PH and the size of the (L2 / L3) message it intends to send in Msg3. For instance, Group 1: PH*Msg3_size < 200 bytes* lOdB, Group 2: 200 bytes* lOdB < PH*Msg3_size < 400 bytes*20dB, Group 3: 400 bytes*20dB < PH*Msg3_size.

[0046] In a seventh example embodiment, the network may also configure SDT PRACH resource where PH is not indicated. Additionally, the network may configure criteria for UE to select between PH and non-PH PRACH resource e.g. based on size of data packet, priority of data, etc.

[0047] In an eighth example embodiment, the PH resource partitioning is only configured for SDT in normal mode and not in coverage enhancement. UE in coverage enhancement is transmittingat maximum power and therefore has no available power headroom. The PRACH configuration is provided to the UE via System Information Block (SIB).

[0048] Referring back to FIG. 2, network configures the UE with an initial assumption based on which the UE should calculate the PH. Based on this, UE determines its PH and selects the appropriate PRACH resource (220) for Msgl transmission (230).

[0049] In an example embodiment, the PH can be calculated based on Msgl transmission power.

[0050] For example, in NR, Msgl transmission power is given byThe PH is the remaining power headroom (i.e. difference between UE’s maximum transmission power and Msgl transmission power).

[0051] In another example, the PH can be calculated based on transmission power of a reference PUSCH allocation, e.g. based on target PUSCH power, MCS and Physical Resource Block (PRB) allocation (e.g. configured PO_PUSCH, MCS = QPSK, R=l / 2, PRB allocation of 4 PRBs). The UE may then assume the same measured pathloss as that of the Random Access (RA). In yet another example, the previous SDT configuration can be considered for PH calculation.

[0052] In another example embodiment, UE with priority data (e.g. alarm report) may select preamble without PH indication (if configured by the network) if PH indication delay is excessive (i.e. UE has to wait a while before the appropriate PRACH occasion is available).

[0053] In FIG. 2 at 240 and 250, network determines UE’s PH based on PRACH resources that the UE selected for Msgl transmission, determines UL grant for Msg3 based on UE’s PH (240), and transmits the Random Access Response to the UE (250).

[0054] In an example embodiment, network initially estimates the Signal to Interference plus Noise Ratio (SINR), Signal to Noise Ratio (SNR), or signal quality from Msgl and selects the baseline MCS for Msg3 transmission. Network then applies the PH information to baseline MCS to determinea final MCS value, PRB value, and power control step size. Alternatively, network directly adjusts the estimated SINR based on the PH information to obtain a final SINR estimate. Based on the final SINR estimate, network determines the final MCS value, PRB value, and power control step size.

[0055] For example, network can adjust the final MCS value based on historical HARQ information for Msg3 transmission.

[0056] For another example, network can also adjust the final MCS value considering potential estimation errors.

[0057] For yet another example, network can also adjust other PHY / MAC parameters for further UE transmission based on the PH information of the UE, such as frequency hopping, HARQ configuration, number of repetitions of Msg3 transmission, Rank, MIMO configuration (e.g. precoding and layers if MIMO is supported), supplementary uplink (SUL). E.g. If PH is determined to be low the network can enable SUL or allocate a higher number of repetitions for Msg3 to increase robustness.

[0058] In FIG. 2 at 260, UE includes Power Headroom Report (PHR) MAC CE in Msg3 transmission if it has additional data to send (260). PH is calculated based on Msg3 transmission power and included as part of Msg3 transmission. The network will then receive accurate PH information together with the Buffer Status Report (BSR).

[0059] Referring now to FIG. 3, this figure shows a block diagram of one possible and nonlimiting example solution (Scheme-2) in which the examples may be practiced. In Scheme-2, Msgl transmission power includes power headroom.

[0060] Msgl transmission power can be adjusted based on PH, i.e. UE with larger power headroom will transmit with higher power. For example, in NR the PRACH transmission power control formula is given b PpRA

[0061] The network can configure different PPRACH, target for different PH ranges with UE with larger PH having a larger PPRACH, target value. Alternately, the UE can increase its transmission power based on either one PH range among multiple PH ranges within which the actual PH falls or directly on the actual PH itself by introducing a power control or adjustment step indexed to the PH value.

[0062] With this approach, the network doesn’t receive explicit indication of PH in Msgl, but Msgl transmission of the UE with higher PH will be received with higher power and hence higher SINR at the network. As a result, the network can select a more aggressive MCS for that UE. With power headroom included in the PRACH preamble transmission power formula, the received PRACH preamble SINR can be used to determine Msg3 MCS and transmission power. Detailed description is given as follows.

[0063] In a first example embodiment, different PPRACH, target values may be configured via SIB for different PH ranges (310) with UE with larger PH having a larger PPRACH, target value. The UE selects one of the configured PPRACH, target values, or determines a PPRACH, target value if PPRACH, target values are not configured (330), based on the PH determined or computed by the UE (320). For instance,where the PH is computed using a reference PRACH target value PPRACH, target, f,c,o- For example:

[0064] In this first example embodiment, the network may determine the UE’s PH range by determining the PPRACH, target value that is closest to the received Msgl power.

[0065] In a further example, P_PRACH_target_O=P_PRACH_target_l. In this case, P_PRACH_target_O is implicitly indicated to the UE by indicating P_PRACH_target_l.

[0066] In a second example embodiment, PPRACH, target is obtained by directly adjusting the reference PRACH target value P_(PRACH, target, f,c,0) based on the computed PH. For example:pRACH, target, f,where A_m is a parameter that may either be configured by the network or up to UE implementation. For example, the parameter may be used to account for implementation margins. In an embodiment, A_m=0. As a result, PPRACH, target is always adjusted such that the transmission power is maximum, and the extent of the received Msgl power above PPRACH, target is directly indicative of the PH.

[0067] In a third example embodiment, a power difference Delta may be defined for different PH,

[0068] In this third example embodiment, the network may determine the PH range based on the extent of the difference between the received Msgl power and the PPRACH, target value according to the table above.

[0069] In a fourth example embodiment, the same PPRACH, target parameter is used by all UEs but a Delta term is added to the power control formula as shown below:pRACH,b, / ,c(0= min{ cMAX, / ,c(0< pRACH, target, / ,c + P^b,f,c + ^PIl} [dBm]where, for example,

[0070] In this fourth example embodiment, the network may determine the PH range based on the Delta value in the table that is closest to the difference between the received Msgl power and the PpRACH, target Value.

[0071] In a fifth example embodiment, a power difference Delta may be defined for different PH and associated to a PRACH repetition (or a secondary transmission). The UE can be configured, for instance, to add Delta on the transmit power of the last repetition of a PRACH transmission. The network can find out the power headroom based on the power difference between the last repetition and a previous one.

[0072] In a sixth example embodiment, the network can configure whether the UE must use PH information in determining Msgl transmission power. This configuration can be via SIB.

[0073] Referring back to FIG. 3, UE selects PRACH resource for SDT and determines Msgl transmission power according to the above steps (320, 330). UE then transmits Msgl (340). Network determines UL grant for Msg3 based on the received PRACH signal strength or signal quality and transmits the Random Access Response to the UE (350).

[0074] Network initially estimates the SINR from Msgl and selects the MCS for Msg3 transmission. For example, network can adjust the final MCS value based on historical HARQ information for Msg3 transmission. For another example, network can also adjust the final MCS value taking into account potential estimation errors.

[0075] In FIG. 3 at 360, UE includes PHR MAC CE in Msg3 transmission if it has additional data to send. PH is calculated based on Msg3 transmission power and included as part of Msg3 transmission. The network will then receive accurate PH information together with the BSR.

[0076] In a further embodiment, both Scheme- 1 and Scheme-2 can be combined as Scheme-3. This may be relevant in cases where there are only fewer set of PRACH resources available to indicate PH status (less partitioning of PRACH resources) and / or finer granularity of PH info is desired (even when PH info is partly implicit). In Scheme-3, the network may configure the UE to:

[0077] Step- 1: first select the Msg 1 transmission power as per the Scheme-2.

[0078] Step-2: given the Msgl transmission power determined in Step-1, the UE is made to perform Msgl PRACH resource selection as per the Scheme- 1. In case of only single partitioning of PRACH resources (i.e., only two sets of PRACH resources), PRACH resource sets can indicate whether or not the UE has PH above a certain PH threshold after determining Msgl transmission power in Step-1. In case of multiple PRACH resource sets are available, different PRACH resource sets can be mapped to different PH range as described under Scheme- 1. Here, the PH range can have finer granularity. Because, the Msgl transmission power has already been adapted in Step-1 based on coarse PH range and hence there may not be high PH availability at the UE.

[0079] As described above (under Scheme-2), the Msgl transmission power impacts the PRACH SINR at the network. Given the PRACH SINR and based on the PRACH resource used by the UE, network can then determine whether (and how much) the UE has the potential to provide higher PRACH SINR. Accordingly, network can determine the UL grant for Msg3.

[0080] The subject matter described herein may be embodied in systems, apparatus, methods, and / or articles depending on the desired configuration. For example, the base stations and user equipment (or one or more components therein) and / or the processes described herein can be implemented using one or more of the following: a processor executing program code, an applicationspecific integrated circuit (ASIC), a digital signal processor (DSP), an embedded processor, a field programmable gate array (FPGA), and / or combinations thereof. These various implementations may include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. These computerprograms (also known as programs, software, software applications, applications, components, program code, or code) include machine instructions for a programmable processor, and may be implemented in a high-level procedural and / or object-oriented programming language, and / or in assembly / machine language. As used herein, the term “computer-readable medium” refers to any computer program product, machine-readable medium, computer-readable storage medium, apparatus and / or device (for example, magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions. Similarly, systems are also described herein that may include a processor and a memory coupled to the processor. The memory may include one or more programs that cause the processor to perform one or more of the operations described herein.

[0081] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

[0082] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0083] It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims. Other embodiments may be within the scope of the following claims. The term “based on” includes “based at least in part on”. The use of the phase “such as” means “such as for example” unless otherwise indicated.

Claims

CLAIMSWhat is claimed is:

1. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to:receive, from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting;determine the apparatus’s PH;select a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; andtransmit the Msgl indicating a PH report to the network node.

2. The apparatus of claim 1, wherein the PRACH resource selection configuration comprises preambles partitioned into one or more groups with each of the one or more groups indicates a range of PH values available at the apparatus.

3. The apparatus of claim 2, wherein number of preambles within each group is configurable such that the preambles are partitioned uniformly or non-uniformly across the one or more groups.

4. The apparatus of claim 2, wherein each preamble group of the one or more groups is mapped to a scheduling configuration so that the apparatus can indicate its scheduling preference by transmitting a preamble of the corresponding preamble group.

5. The apparatus of claim 2, wherein a group of preambles is reserved to indicate that the apparatus will send the PH report in an initial uplink resource allocation, Msg3, without small data transmission, SDT.

6. The apparatus of claim 1, wherein the PRACH resource selection configuration comprises PRACH occasions partitioned into one or more groups wherein each of the one or more groups indicates a range of PH values available at the apparatus.

7. The apparatus of claim 6, wherein a timing mask is used to indicate the grouping for each PRACH occasion starting from a reference point.

8. The apparatus of claim 1, wherein the PRACH resource selection configuration comprises different numbers of PRACH repetitions for different levels of the PH.

9. The apparatus of claim 8, wherein PRACH target power, PPRACH, target, can be adjusted with the number of PRACH repetitions.

10. The apparatus of claim 1, wherein the PRACH resource selection configuration comprises a combination of the preamble partitioning and the PRACH occasion partitioning.

11. The apparatus of claim 1, wherein the PRACH resource selection configuration comprises one or more partitions for SDT.

12. The apparatus of claim 1, wherein the PH is determined based on a Msgl transmission power or a reference physical uplink shared channel, PUSCH, transmission power.

13. The apparatus of claim 1, wherein the apparatus selects a preamble without a PH indication when the apparatus is transmitting a priority data.

14. The apparatus of claim 1, wherein the instructions, when executed with the at least one processor, cause the apparatus to:transmit a Msg3 to the network node, comprising a PH report medium access control control element, MAC CE, when the apparatus has additional data to send.

15. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed with the at least one processor, cause the apparatus at least to:transmit a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment;receive a random access preamble, Msgl, indicating PH report from the user equipment.determine an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; andtransmit a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

16. The apparatus of claim 15, wherein the PRACH resource selection configuration comprises preambles partitioned into one or more groups with each of the one or more groups indicates a range of PH values available at the user equipment.

17. The apparatus of claim 16, wherein number of preambles within each group is configurable such that the preambles are partitioned uniformly or non-uniformly across the one or more groups.

18. The apparatus of claim 16, wherein different groupings are configured for different user equipment power classes.

19. The apparatus of claim 16, wherein each preamble group of the one or more groups is mapped to a scheduling configuration so that the user equipment can indicate its scheduling preference by transmitting a preamble of the corresponding preamble group.

20. The apparatus of claim 16, wherein a group of preambles is reserved to indicate that the user equipment will send the PH report in the Msg3 without the SDT.

21. The apparatus of claim 15, wherein the PRACH resource selection configuration comprises PRACH occasions partitioned into one or more groups with each of the one or more groups indicates a range of PH values available at the user equipment.

22. The apparatus of claim 21, wherein a timing mask is used to indicate the grouping for each PRACH occasion starting from a reference point.

23. The apparatus of claim 15, wherein the PRACH resource selection configuration comprises different number of PRACH repetitions configured for different levels of the PH.

24. The apparatus of claim 23, wherein transmitting the PRACH resource selection configuration for PH reporting comprises the instructions, when executed with the at least one processor, cause the apparatus to:detect blindly the number of PRACH repetitions in a PRACH detection process to get the PH report from the Msgl.

25. The apparatus of claim 15, wherein transmitting the PRACH resource selection configuration for PH reporting comprises the instructions, when executed with the at least one processor, cause the apparatus to:adjust the preamble partitioning or the PRACH occasion partitioning based on received responses from the user equipment wherein the PRACH resources were initially partitioned uniformly or equally of the PRACH preambles or the PRACH occasions.

26. The apparatus of claim 15, wherein the PRACH resource selection configuration comprises a combination of the preamble partitioning and the PRACH occasion partitioning.

27. The apparatus of claim 15, wherein the PRACH resource selection configuration comprises a combination of the preamble partitioning and PRACH subcarrier offsets associated to the PH.

28. The apparatus of claim 15, wherein partitioning of the PRACH resources is configured based in part on size of a message the user equipment intends to transmit in the Msg3.

29. The apparatus of claim 15, wherein one or more partitioned PRACH resources are configured to indicate non-PH and criteria for selecting between PH and non-PH PRACH resource comprising size of data packet or priority of data.

30. The apparatus of claim 15, wherein the instructions, when executed with the at least one processor, cause the apparatus to:receive the Msg3 from the user equipment comprising a PH report medium access control control element, MAC CE, when the user equipment has additional data to send.

31. The apparatus of claim 15, wherein determining an initial uplink resource allocation for the Msg3 comprises the instructions, when executed with the at least one processor, cause the apparatus to:estimate the signal to interference plus noise ratio, SINR, from the Msgl;select a baseline modulation and coding scheme, MCS, for the Msg3 transmission; andapply the PH information to the baseline MCS to determine a final MCS value, Physical Resource Block, PRB, value, and power control step size.

32. The apparatus of claim 15, wherein determining an initial uplink resource allocation for the Msg3 comprises the instructions, when executed with the at least one processor, cause the apparatus to:adjust the estimated SINR based on the PH information to obtain a final SINR estimate; anddetermine a final MCS value, PRB value, and power control step size based on the final SINR estimate.

33. The apparatus of claim 31 or 32, wherein the final MCS value is adjusted based on a historical hybrid automatic repeat request, HARQ, information for the Msg3 transmission.

34. The apparatus of claim 31 or 32, wherein the final MCS value is adjusted based in part on potential estimation errors.

35. The apparatus of claim 31 or 32, wherein one or more physical / medium access control, PHY / MAC, parameters are adjusted for further user equipment transmission based on the PH information of the user equipment.

36. The apparatus of claim 35, wherein the PHY / MAC parameters comprise frequency hopping, HARQ configuration, number of repetitions of the Msg3 transmission, rank, multiple-input multiple-output, MIMO, configuration, and supplementary uplink, SUL.

37. A method comprising:receiving, with a user equipment from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting;determining the user equipment’s PH;selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; andtransmitting the Msgl indicating a PH report to the network node.

38. A method comprising:transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment;receiving a random access preamble, Msgl, indicating PH report from the user equipment;determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; andtransmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

39. An apparatus comprising:means for receiving, from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting;means for determining the apparatus’s PH;means for selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; andmeans for transmitting the Msgl indicating a PH report to the network node.

40. An apparatus comprising:means for transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment;means for receiving a random access preamble, Msgl, indicating PH report from the user equipment;means for determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; andmeans for transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

41. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following:causing receiving, with a user equipment from a network node, a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting;causing determining the user equipment’s PH;causing selecting a PRACH resource for a random access preamble, Msgl, transmission based on the received PRACH resource selection configuration; andcausing transmitting the Msg1 indicating a PH report to the network node.

42. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following:causing transmitting a physical random access channel, PRACH, resource selection configuration for power headroom, PH, reporting to a user equipment;causing receiving a random access preamble, Msgl, indicating PH report from the user equipment;causing determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on the received user equipment’s PH; andcausing transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

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