Apparatus and method for power headroom indication for small data transmission

Abstract

An apparatus configured to: determine a physical random access channel, PRACH, target power, P PRACH,target, value based on a power headroom, PH, determined or computed; determine a transmission power for a random access preamble, Msg1, according to the determined P PRACH,target value; and transmit the Msg1.

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 loT (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: determine a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; determine a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and transmit the Msgl.

[0005] In accordance with one aspect, a method comprising: determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH,determined or computed; determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and transmitting the Msgl.

[0006] In accordance with one aspect, an apparatus comprising: means for determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; means for determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and means for transmitting the Msgl.

[0007] In accordance with one aspect, a non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; causing determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and causing transmitting the Msgl.

[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: configure different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; determine an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; 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: configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; 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 configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; means for determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; 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 configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; causing determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; 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 Power eMBB Enhanced Mobile BroadbandFR1 Frequency Range 1FR2 Frequency Range 2 gNB Next generation Node-B loT Internet of thingsLCG Logical Channel GroupLPWA Low Power Wide AreaLTE-M Long-Term Evolution Machine Type CommunicationMAC 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, embodimentsof 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 (loT) 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 loT 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. Power headroom 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 loT 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 loT 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 uplink channel 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, thusreducing the network capacity. Therefore, a method is needed to allow loT 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, PPRACH, 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 and coarser 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 transmitting at 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 appropriatePRACH 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 determine a 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 bPpRA

[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. Withpower 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:target, f,c,0 + PLb.f.c)

[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_0 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,c=^PRACH, target, fwhere 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

[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: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 indicatewhether 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 computer programs (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 memorymay 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

What is claimed is:

1. 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: determine a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; determine a transmission power for a random access preamble, Msg 1 , according to the determined PPRACH, target value; and transmit the Msg 1.

2. The apparatus of claim 1, wherein the instructions, when executed with the at least one processor, cause the apparatus to: receive a configuration of different PRACH target power, PPRACH, target, values for different PH ranges from a network node; and determine the PPRACH, target value by selecting one of the configured PPRACH, target values.

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

4. The apparatus of claim 3, wherein the PH is calculated based on a Msg3 transmission power and included as part of the Msg3 transmission.

5. The apparatus of claim 1, wherein the Msgl is transmitted on a selected PRACH resource which is configured for small data transmission, SDT.

6. 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: configure different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; determine an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; and transmit a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

7. The apparatus of claim 6, wherein configuring a PRACH target power, PPRACH, target, value for each PH comprises the instructions, when executed with the at least one processor, cause the apparatus to: configure different PPRACH, target values via system information block, SIB, for different PH ranges of the user equipment with larger PH having a larger PPRACH, target value.

8. The apparatus of claim 6, wherein configuring different PRACH target power, PPRACH, target, values for different PH ranges comprises the instructions, when executed with the at least one processor, cause the apparatus to: obtain each of the different PPRACH, target values by adjusting a reference PRACH target value with a respective computed PH.

9. The apparatus of claim 6, wherein a power difference delta is defined for different PH.

10. The apparatus of claim 9, wherein the power difference delta is further associated to a PRACH repetition.

11. The apparatus of claim 6, wherein a delta term is added to a PRACH power control formula.

12. The apparatus of claim 6, wherein determining the initial uplink grant for the Msg3 based on the received PRACH signal strength or signal quality comprises the instructions, when executed with the at least one processor, cause the apparatus to: adjust a final modulation and coding scheme, MCS, value based on a historical hybrid automatic repeat request, HARQ, information for the Msg3 transmission; or adjust the final MCS value based in part on potential estimation errors.

13. The apparatus of claim 6, 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.

14. 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, configuration comprising a configuration of PRACH resource selection and a configuration of different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges;select one of the configured PPRACH, target values based on a PH determined or computed; determine a random access preamble, Msgl, transmission power according to the selected PPRACH, target value; select a PRACH resource for the Msgl transmission; transmit the Msgl indicating a PH information to the network node; and receive, from the network node, an initial uplink resource allocation for a scheduled transmission, Msg3.

15. 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, configuration comprising a configuration of PRACH resource selection and a configuration of different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; receive a random access preamble, Msgl, indicating a PH information from a PRACH resource; determine if the user equipment can provide higher PRACH signal to interference plus noise ratio, SINR, and by how much based on an estimated PRACH SINR and the PRACH resource used by the user equipment; anddetermine an initial uplink resource allocation for a scheduled transmission, Msg3, based on the if the user equipment can provide higher PRACH SINR and by how much determination.

16. The apparatus of claim 15, wherein only two sets of PRACH resources configured, the PRACH resource sets indicates whether or not the user equipment has a PH above a certain PH threshold after determining the Msgl transmission power.

17. A method comprising: determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH , target value; and transmitting the Msgl.

18. A method comprising: configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; and transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

19. An apparatus comprising: means for determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed;means for determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and means for transmitting the Msgl.

20. An apparatus comprising: means for configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; means for determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; and means for transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

21. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following: causing determining a physical random access channel, PRACH, target power, PPRACH, target, value based on a power headroom, PH, determined or computed; causing determining a transmission power for a random access preamble, Msgl, according to the determined PPRACH, target value; and causing transmitting the Msg 1.

22. A non-transitory computer-readable medium comprising program instructions stored thereon for performing at least the following:causing configuring different physical random access channel, PRACH, target power, PPRACH, target, values for different power headroom, PH, ranges to a user equipment; causing determining an initial uplink resource allocation for a scheduled transmission, Msg3, based on a received PRACH signal strength or signal quality; and causing transmitting a random access response, Msg2, comprising the initial uplink resource allocation to the user equipment.

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