Enhanced random access in cellular communication networks

Abstract

According to one example aspect of the present disclosure, an apparatus is provided. The apparatus comprises means for transmitting a random access preamble with repetitions to a wireless network node using a number of repetitions, means for selecting a waveform for transmission of a connection request based on the number of repetitions and one of at least one repetition threshold, and means for sending a connection request to the wireless network node using the selected waveform.

Description

Technical Field

[0001] Various example embodiments relate generally to cellular communication systems, and more particularly to random access in such systems. Background Art

[0002] Random access can be used to access a wireless communication network, for example, to request a dedicated connection to be arranged for a wireless terminal requesting access. Random access can be used for various cellular communication networks, such as cellular communication networks operating according to 5G radio access technology. 5G radio access technology may also be referred to as new radio NR access technology, and the third generation partnership project 3GPP sets standards for 5G / NR. Generally, it is necessary to provide enhanced methods, devices, and computer programs related to random access in a cellular communication network. This enhancement may also be beneficial to other wireless communication networks, such as future 6G networks. Summary of the invention

[0003] According to some aspects, the subject matter of the independent claims is provided. Some example embodiments are defined in the dependent claims.

[0004] The independent claims define the scope of protection of various exemplary embodiments of the present disclosure. Exemplary embodiments and features described in this specification that do not belong to the scope of the independent claims (if any) are to be construed as examples that help understand the various exemplary embodiments of the present disclosure.

[0005] According to a first aspect of the present disclosure, there is provided an apparatus, the apparatus comprising: a component for sending a random access preamble with repetitions to a radio network node using a certain number of repetitions, a component for selecting a waveform for transmission of a connection request based on the number of repetitions and one of at least one repetition threshold, and a component for sending the connection request to the radio network node using the selected waveform. The apparatus of the first aspect may be a user equipment or a control device configured to control its functions (possibly when installed therein).

[0006] Example embodiments of the first aspect may include at least one feature from the following bulleted list or any combination of the following features:

[0007] wherein the random access preamble is sent in the first message of a 4-step random access procedure and the connection request is sent in the third message of the 4-step random access procedure;

[0008] wherein the means for selecting a waveform further comprises: means for comparing the number of repetitions with the one of the at least one repetition thresholds, and means for selecting a waveform for transmission of a connection request based on the comparison

[0009] Components;

[0010] The component for selecting a waveform further comprises: a component for selecting a first waveform or

[0011] The second waveform is a component of a waveform used for transmission of a connection request;

[0012] wherein the first waveform is more robust than the second waveform;

[0013] The first waveform is discrete Fourier transform spread spectrum orthogonal frequency division DFT-s-OFDM,

[0014] And the second waveform is cyclic prefix orthogonal frequency division CP-OFDM;

[0015] wherein the one of the at least one repetition threshold and the number of repetitions is a beam number, and the apparatus further comprises: means for selecting a first waveform when the number of repetitions is less than or equal to the one of the at least one repetition threshold, and means for selecting a second waveform when the number of repetitions is greater than the one of the at least one repetition threshold;

[0017] wherein the one of the at least one repetition threshold and the number of repetitions are a number of repetitions, and the apparatus further comprises: means for selecting a second waveform when the number of repetitions is less than or equal to the one of the at least one repetition threshold, and means for selecting a first waveform when the number of repetitions is greater than the one of the at least one repetition threshold;

[0018] The apparatus further comprises: receiving a configuration for random access from a wireless network node

[0019] means for configuring at least one repetition threshold for transmission of a preamble;

[0020] The device further comprises: after receiving the configuration, ignoring the

[0021] means for transforming precoder parameters of the requested transmission;

[0022] · wherein the repeat number is the Msg1 repeat number.

[0023] According to a second aspect of the present disclosure, there is provided an apparatus, comprising: a component for receiving a random access preamble with repetitions from a user equipment using a certain number of repetitions, a component for selecting a waveform for receiving a connection request based on the number of repetitions and one of at least one repetition threshold, and a component for receiving a connection request from the user equipment using the selected waveform. The apparatus of the second aspect may be a radio network node or a control device configured to control its functions (possibly when installed therein).

[0024] According to a third aspect, there is provided a first method, the first method comprising: sending, by an apparatus, a random access preamble with repetitions to a radio network node using a certain number of repetitions, selecting, by the apparatus, a waveform for transmission of a connection request based on the number of repetitions and one of at least one repetition threshold, and sending, by the apparatus, the connection request to the radio network node using the selected waveform. The first method may be performed by a user equipment or a control device configured to control its functions (possibly when installed therein).

[0025] According to a fourth aspect, a second method is provided, the second method comprising: receiving, by an apparatus, a random access preamble with repetitions from a user equipment using a certain number of repetitions, selecting, by the apparatus, a waveform for receiving a connection request based on the number of repetitions and one of at least one repetition threshold, and receiving, by the apparatus, a connection request from the user equipment using the selected waveform. The second method may be performed by a radio network node or a control device configured to control its functions (possibly when installed therein).

[0026] According to a fifth aspect of the present disclosure, a device is provided, the device comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processing core, enable the device to at least: send a random access preamble with repetitions to a wireless network node using a certain number of repetitions, select a waveform for transmission of a connection request based on the number of repetitions and one of at least one repetition thresholds by the device, and send a connection request to the wireless network node using the selected waveform by the device. The device of the fifth aspect may be a user device or a control device configured to control its functions (possibly when installed therein).

[0027] According to a sixth aspect of the present disclosure, there is provided an apparatus, the apparatus comprising at least one processing core, at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processing core, enable the apparatus to at least: receive a random access preamble with repetitions from a user equipment using a certain number of repetitions, select a waveform for receiving a connection request based on the number of repetitions and one of at least one repetition thresholds by the apparatus, and receive a connection request from the user equipment using the selected waveform by the apparatus. The apparatus of the second aspect may be a wireless network node or a control device configured to control its functions (possibly when installed therein).

[0028] According to a seventh aspect of the present disclosure, a non-transitory computer-readable medium is provided, on which a computer-readable instruction set is stored, and when the instruction set is executed by at least one processor, the device at least performs a first method. According to an eighth aspect of the present disclosure, a non-transitory computer-readable medium is provided, on which a computer-readable instruction set is stored, and when the instruction set is executed by at least one processor, the device at least performs a second method.

[0029] According to a ninth aspect of the present disclosure, there is provided a computer program, the computer program comprising instructions, when the program is executed by a device, the instructions cause the device to perform a first method. According to a tenth aspect of the present disclosure, there is provided a computer program, the computer program comprising instructions, when the program is executed by a device, the instructions cause the device to perform a second method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 illustrates examples of network scenarios according to at least some example embodiments;

[0031] Figure 2 illustrates a 4-step RACH procedure according to at least some example embodiments;

[0032] Figure 3 An example association between PRACH repetition number and SS-RSRP is illustrated;

[0033] Figure 4 illustrates a signaling diagram according to at least some example embodiments;

[0034] Figure 5 illustrates example apparatus capable of supporting at least some example embodiments;

[0035] Figure 6 A flow chart of a first method according to at least some example embodiments is illustrated. DETAILED DESCRIPTION

[0036] Random access may be enhanced by the process described herein. More specifically, random access in a cellular communication network may be enhanced by enabling a user equipment UE to select a waveform for sending a connection request, such as the third message (Msg3) of a 4-step random access procedure. The UE may select a waveform based on the number of repetitions of a random access preamble, such as the first message (Msg1) of a 4-step random access procedure. The number of repetitions may refer to the number of beams or the number of repetitions used to send a random access preamble with repetitions, and therefore, the number of repetitions may at least implicitly represent the link budget that the UE is expected to experience during the transmission of the random access preamble and the connection request. Therefore, the UE may select a waveform for the transmission of a connection request by considering its expected link budget.

[0037] Figure 1 Examples of network scenarios are illustrated in accordance with at least some example embodiments. Figure 1 In an example scenario, there may be a beam-based wireless communication system including: UE 110, radio network node 120, and core network element 130. UE 110 may connect to radio network node 120 via an air interface using beam 112 or 114. In some example embodiments, UE 110 may sweep a transmit beam from beam 112 to beam 114 during a random access procedure.

[0038] For example, UE 110 may include a smartphone, a cellular phone, a machine-to-machine (M2M) node, a machine-type communication (MTC) node, an Internet of Things (IoT) node, an automobile telemetry unit, a laptop, a tablet computer, or virtually any type of suitable wireless terminal. Figure 1 In the example system of , UE 110 may wirelessly communicate with radio network node 120, for example, via beam 112 or beam 114. Radio network node 120 may be considered a serving node for UE 110, and one cell of radio network node 120 may be a serving cell for UE 110.

[0039] The air interface between the UE 110 and the radio network node 120 may be configured according to a radio access technology RAT, both of which are configured to support the RAT. Examples of cellular RATs include Long Term Evolution LTE, New Radio NR (also known as fifth generation 5G radio access technology), and MulteFire.

[0040] For example, in the context of LTE, the radio network node 120 may be referred to as an eNB, while in the context of NR, the radio network node 120 may be referred to as a gNB. In some example embodiments, the radio network node 120 may be referred to as a transmission reception point (TRP), or may control multiple TRPs, which may be collocated or non-collocated. In any case, the example embodiments of the present disclosure are not limited to any particular wireless technology. Rather, the example embodiments may be utilized in any wireless communication system in which random access with repetition is used.

[0041] The radio network node 120 may be connected to the core network 130 via an interface 125 directly or via at least one intermediate node. The core network 130 may also be connected to another network ( Figure 1 The radio network node 120 may be coupled to the core network 130 or another core network directly or via at least one intermediate node, through which connection to other networks may be obtained, for example, via a global interconnected network.

[0042] At least some example embodiments of the present disclosure relate to dynamic switching between at least two waveforms used to send a connection request in a random access procedure. For example, example embodiments of the present disclosure may be applied in a cellular communication network to enable dynamic waveform switching between discrete Fourier transform spread spectrum orthogonal frequency division multiplexing DFT-s-OFDM and cyclic prefix CP-OFDM. The dynamic switching may be applied to, for example, the physical uplink shared channel PUSCH transmission of the third message (Msg3) in a 4-step random access channel RACH procedure. In some example embodiments, the dynamic switching may depend on the transmission of the first message (Msg1) with a repeated 4-step RACH procedure.

[0043] In general, even if DFT-s-OFDM and CP-OFDM are used as examples, the example embodiments of the present disclosure may be applied to select between any at least two waveforms, some of which are more robust than other waveforms in terms of link budget. For example, if there are two waveforms, the waveform for transmission of a connection request may be selected between a first waveform (such as DFT-s-OFDM) and a second waveform (such as CP-OFDM), one of which is more robust than the other. In some example embodiments, DFT-s-OFDM may be more robust than CP-OFDM, but note that DFT-s-OFDM may not always be more robust than CP-OFDM.

[0044] For example, NR supports both waveforms in uplink UL DFT-s-OFDM and CP-OFDM. DFT-s-OFDM supports single-layer transmission, while CP-OFDM supports multi-layer UL transmission. However, a network node such as a radio network node 120 may semi-statically configure a single waveform for UL transmission. For example, the radio network node 120 may configure only one waveform. Therefore, even if the UE 110 will support multiple transmit antennas, if it is configured with a DFT-s-OFDM waveform, it can be expected that it will use one layer for transmission, such as using only a single layer. To this end, the network node may configure a CP-OFDM waveform for UL transmission to utilize multiple-input multiple-output MIMO transmission in the UL. On the other hand, compared to CP-OFDM, DFT-s-OFDM provides a lower peak-to-average power ratio (PAPR) and therefore provides greater deliverable power at the power amplifier of the UE 110. Therefore, when UE 110 is at the cell edge, the DFT-s-OFDM waveform provides better coverage compared to CP-OFDM due to power efficiency, which is achieved through lower PAPR.

[0045] The radio network node 120 (such as a gNB) may configure the UL waveform in a semi-static manner via radio resource control RRC signaling, for example in the current NR Rel-15 / Rel-16 / Rel-17 specifications (3GPP TR 38.214 Section 6.1.3). However, it would be beneficial to support dynamic switching of waveforms in UL transmissions in order to exploit the benefits of both UL MIMO transmission of CP-OFDM and the power efficiency of DFT-s-OFDM. That is, the rationale for dynamic waveform switching can also be explained by considering that the DFT-S-OFDM waveform has a lower PAPR compared to the CP-OFDM waveform and is therefore beneficial for UL coverage limited scenarios. However, if the UL waveform were to be configured via RRC, such a limitation would in practice set a large obstacle for cell edge UEs to switch to the DFT-S-OFDM waveform.

[0046] Figure 2 The 4-step RACH process according to at least some example embodiments is illustrated. Figure 1 UE 110 and radio network node 120. Time passes from top to bottom.

[0047] At step 210, the UE 110 may send a random access preamble to the radio network node 120 (such as a gNB) in the first message of a 4-step RACH procedure (Msg1, also referred to as physical RACH, PRACH). The UE 110 may, for example, send a specific preamble to the radio network node 120 via PRACH using specific resources (such as RACH opportunities). At step 220, the radio network node 120 may send a random access response message in response to receiving the random access preamble, which may include a detected preamble identity, a timing advance command, a temporary cell radio network temporary identifier, and an UL grant for transmission of a connection request (e.g., Msg3 on PUSCH). The random access response message may be the second message (Msg2) of the 4-step RACH procedure.

[0048] At step 230, UE 110 may respond to the random access response message by sending a connection request. The connection request may be an RRC request. The connection request may be sent in the third message (Msg3) of the 4-step RACH procedure.

[0049] For example, the connection request may be sent on a PUSCH scheduled in an UL grant, possibly with an identifier for contention resolution. At step 240, the radio network node 120 may send a contention resolution message as a fourth message (Msg4) of the 4-step RACH procedure in response to receiving the connection request. The contention resolution message may be a setup message, such as an RRC setup message. For example, the radio network node 120 may send a contention resolution message with an identifier for contention resolution.

[0050] Upon or after receiving the contention resolution message, if the contention resolution identifier of UE 110 is carried in the contention resolution information, UE 110 may send an acknowledgement on the physical uplink control channel PUCCH, thereby completing the 4-step RACH procedure.

[0051] In some example embodiments, there may also be a preliminary step of sending and receiving synchronization signal blocks SSBs before step 210. That is, downlink beam scanning may be performed before step 210, which may not be a formal part of the RACH process. As a result of this preliminary step, the UE 110 may select an index of a preferred SSB beam and decode the associated physical broadcast channel PBCH of the master information block MIB, system information block SIB, etc. The index may also be used by the UE 110 to identify a suitable RACH opportunity for transmission of a random access preamble (such as Msg1) based on the SSB to RACH opportunity mapping conveyed by SIB1. The radio network node 120 may then use the SSB beam index selected by the UE 110 to transmit a random access response message, such as Msg2.

[0052] Multiple transmissions of the random access preamble may be introduced to extend the coverage of the UE 110 during random access. For example, multiple PRACH transmissions may be introduced to extend the coverage of the PRACH channel. Thus, the UE 110 may send the PRACH multiple times (i.e., PRACH repetitions) before receiving a random access response from the radio network node 120 to improve detection performance. In order to decide how many repetitions the UE 110 needs to perform for a certain PRACH transmission, one metric to consider may be the synchronization signal reference signal received power SS-RSRP of the associated SSB. Different SS-RSRP thresholds may be defined, and each threshold may be associated with a number of repetitions.

[0053] Figure 3 An example association between the number of PRACH repetitions and SS-RSRP is shown. Figure 3 As shown in , UE 110 may measure SS-RSRP of about -82dBm associated with 2 PRACH repetitions. Radio network node 120 may then be able to infer the channel condition of UE 110 by the number of repetitions of the random access preamble sent by UE 110 (e.g., Msg1). In some example embodiments of the present disclosure, such implicit information may ultimately be used to determine the waveform of a subsequent connection request, such as Msg3.

[0054] Alternatively or additionally, multiple transmissions of a random access preamble (e.g., Msg1) with beam sweeping may be utilized. In some example embodiments, UE 110 may know the correct panel by listening to the SSBs and sweep a limited number of transmission beams (e.g., 4) on the same panel. The selection of the limited transmit beams may be determined by UE 110 based on the SSBs received from radio network node 120, but the number of beams is typically unknown to radio network node 120 and depends on the implementation of UE 110.

[0055] The number of beams used by the UE 110 for transmission of the random access preamble by frequency sweeping (which may be lower than or equal to the number of repetitions of the random access preamble, e.g., the number of PRACH repetitions) may also be used as an indicator of the link budget of the UE 110. Thus, the number of beams may indicate whether the connection request should be sent using a first waveform (e.g., DFT-s-OFDM) or a second waveform (e.g., CP-OFDM). For example, the larger the number of beams per panel of the UE 110, the narrower such beams are expected to be, the greater the peak gain, and ultimately the better UL link budget will result. In the case of beam sweeping, the radio network node 120 may infer that a large number of beams may be associated with a less robust waveform, such as CP-OFDM, while a small number of beams may be associated with a more robust waveform, such as DFT-s-OFDM. However, DFT-s-OFDM may not always be more robust than CP-OFDM, and in such a case, a large number of beams may be associated with DFT-s-OFDM, and a small number of beams may be associated with CP-OFDM.

[0056] The repetition of the random access preamble transmission may allow UE 110 to repeat the transmission on multiple different RACH occasions before receiving a random access response message. In some example embodiments, UE 110 may be a coverage enhancement CE UE and initiate the repetition when RSRP is very low, in which case the transmission of the corresponding connection request may suffer from poor performance due to the distance between UE 110 and radio network node 120.

[0057] The number of repetitions of the random access preamble may need to be UE-specific. Therefore, if there is no rule or configuration for selecting a robust waveform for transmission of a corresponding connection request, even if the connection request will be sent repeatedly, the UE 110 may experience insufficient coverage for the transmission of the connection request due to the lack of selection of an appropriate waveform. Furthermore, it is reasonable to assume that if the UE 110 evaluates that the coverage of the random access preamble transmission is poor, all available tools should be used to improve the coverage of the connection request, such as in NR.

[0058] Therefore, in addition to considering semi-static configurations provided by higher layers and the radio network node 120, improvements need to be provided to allow UE 110 (e.g., CE UE) to select a waveform for its connection request transmission taking into account the link budget that the UE 110 is expected to experience during the repetition of the random access preamble transmission. Another problem may be that the transform precoder parameters of the connection request, such as msg3-transformPrecoder, may be configured before the transmission of the random access preamble. In this case, the transform precoder parameters will be configured without taking into account the actual channel conditions of the specific UE (e.g., UE 110).

[0059] Thus, example embodiments of the present disclosure enable UE 110 (such as a CE UE) to select a waveform, such as Msg3, for transmission of a connection request in a 4-step random access procedure. UE 110 may select a waveform, such as Msg1 repetition, for example, during repetitions of transmission of a random access preamble, regardless of the waveform configured by radio network node 120 for transmission of a connection request, such as using parameter msg3-transformPrecoder. In some example embodiments, a set of conditions is also provided on which UE 110 may perform waveform selection for transmission of a connection request. Radio network node 120 may select a waveform for reception of a connection request in the same manner as UE 110.

[0060] A repetition threshold associated with a beam, such as Msg1_beams_repetitions_thr, may be defined as a threshold for distinguishing whether a random access preamble with repetitions is transmitted using a lower number of beams (e.g., 2 beams) or a higher number of beams (e.g., 8 beams), such as in Msg1. In some example embodiments, instead of or in addition to applying multiple beams, a repetition threshold associated with the number of repetitions, such as Msg1_number_of_repetitions_thr, may be applied as a threshold for distinguishing whether a random access preamble is transmitted using a lower number of repetitions (e.g., 2 repetitions) or a higher number of repetitions (e.g., 8 beams). In general, the number of repetitions may refer to the number of beams or the number of repetitions used for transmission of a random access preamble.

[0061] The radio network node 120 (e.g., gNB) may configure at least one repetition threshold (Msg1_beams_repetitions_thr and / or Msg1_number_of_repetitions_thr) for the UE 110, and the UE 110 may be allowed to select the most appropriate waveform for subsequent transmissions of the connection request, such as Msg3, based on a comparison between the configured threshold(s) and the decision made by the UE 110 itself regarding the transmission of the random access preamble.

[0062] In some example embodiments, if a repetition threshold (parameter Msg1_beams_repetitions_thr or parameter Msg1_number_of_repetitions_thr) is received by UE 110 that is capable of interpreting and utilizing them, UE 110 may ignore the transform precoder parameters, such as the content of the higher layer parameter msg3-transformPrecoder.

[0063] In some example embodiments, if these two repetition thresholds (parameter Msg1_beams_repetitions_thr and parameter Msg1_number_of_repetitions_thr) are received by UE 110 that is capable of interpreting and utilizing them, then in consideration of the limited beamforming capability of UE 110, when repetitions of the random access preamble are transmitted using different transmit beams, UE 110 may use the threshold associated with the beam (Msg1_beams_repetitions_thr). When repetitions of the random access preamble are transmitted using the same transmit beam or different transmit beams, UE 110 may use the threshold associated with the number of repetitions (Msg1_number_of_repetitions_thr).

[0064] In some example embodiments, UE 110 may send a random access preamble with repetitions based on RSRP measurements performed by UE 110, depending on the number of beams available at UE 110 through implementation or depending on the measured RSRP.

[0065] If the repetition threshold configured by the radio network node 120 is the number of beams (Msg1_beams_repetitions_thr), the number of repetitions may also refer to the number of beams. In this case, if the UE 110 uses different transmit beams to send the connection request, the UE 110 may ignore the transform precoder parameters configured by the radio network node 120. For example, the UE 110 may ignore the content of the higher layer parameter msg3-transformPrecoder. The UE 110 may then select a waveform for transmission of the connection request, such as a UL waveform for subsequent Msg3 transmissions, as shown below:

[0066] UE 110 may compare the number of beams used for transmission with repeated random access preambles with a repetition threshold, and if the number of beams used for transmission with repeated random access preambles is greater than the repetition threshold, UE 110 may select a second waveform (such as CP-OFDM) for transmission of the connection request. For example, if the number of beams for Msg1 repetitions > Msg1_beams_repetitions_thr, the link budget may be considered good enough. Therefore, CP-OFDM may be used as the UL waveform for Msg3 transmission;

[0068] If the number of beams used for transmission with repeated random access preambles is less than or equal to the repetition threshold, UE 110 may select the first waveform (e.g., DFT-s-OFDM) for transmission of the connection request. For example, if the number of beams for Msg1 repetitions ≤ Msg1_beams_repetitions_thr, the link budget may be considered not good enough. Therefore, DFT-s-OFDM may be used as the UL waveform for Msg3 transmission.

[0069] In this case, it may be assumed that UE 110 is limited by its capabilities and cannot generate more than a number of beams for transmitting the random access preamble at a certain beamforming gain. Therefore, UE 110 may send a number of repetitions of the random access preamble equal to the number of beams that UE 110 is capable of generating, during transmission of the connection request, with more beams being associated with higher gains and, thus, better link budgets.

[0070] If the repetition threshold configured by the radio network node 120 is the number of repetitions (Msg1_number_of_repetitions_thr), the number of repetitions may also refer to the number of repetitions. In this case, if the UE 110 uses a different transmit beam to transmit the connection request, the UE 110 may ignore the transform precoder configured by the radio network node 120 for the transmission of the connection request. For example, the UE 110 may ignore the content of the higher layer parameter msg3-transformPrecoder. The UE 110 may then select a waveform for the transmission of the connection request, such as a UL waveform for subsequent Msg3 transmissions, as shown below:

[0071] UE 110 may compare the number of repetitions for transmission with repeated random access preambles with a repetition threshold, and if the number of repetitions for transmission with repeated random access preambles is greater than the repetition threshold, UE 110 may select a first waveform (such as DFT-s-OFDM) for transmission of the connection request. For example, if the number of Msg1 repetitions > Msg1_number_of_repetitions_thr, it may be considered that the link budget is not good enough. Therefore, DFT-s-OFDM may be used as the UL waveform for Msg3 transmission;

[0072] If the number of repetitions for transmissions with repeated random access preambles is less than or equal to the repetition threshold, UE 110 may select a second waveform (e.g., CP-OFDM) for transmission of the connection request.

[0073] ≤Msg1_number_of_repetitions_thr, the link budget can be considered good enough.

[0074] Therefore, CP-OFDM can be used as the UL waveform for Msg3 transmission.

[0075] In this case, it can be assumed that UE 110 is not limited by its capabilities and is able to generate multiple beams with a certain beamforming gain, for example based on the measured SS-RSRP. This means that the larger the number of repetitions and the greater the number of beams, the worse the channel conditions experienced by UE 110.

[0076] If the repetition threshold configured by the radio network node 120 is the number of repetitions (Msg1_number_of_repetitions_thr), the number of repetitions may also refer to the number of repetitions. In this case, if the UE 110 transmits the connection request using a single (e.g., only one) transmit beam, the UE 110 may select a waveform for transmission of the connection request, such as a UL waveform for subsequent Msg3 transmission, as shown below:

[0077] UE 110 may compare the number of repetitions for transmission with repeated random access preambles with a repetition threshold, and if the number of repetitions for transmission with repeated random access preambles is greater than the repetition threshold, UE 110 may select a first waveform (such as DFT-s-OFDM) for transmission of the connection request. For example, if the number of Msg1 repetitions > Msg1_number_of_repetitions_thr, it may be considered that the link budget is not good enough. Therefore, DFT-s-OFDM may be used as the UL waveform for Msg3 transmission;

[0078] If the number of repetitions for transmissions with repeated random access preambles is less than or equal to the repetition threshold, UE 110 may select a second waveform (e.g., CP-OFDM) for transmission of the connection request.

[0079] ≤Msg1_number_of_repetitions_thr, the link budget can be considered good enough.

[0080] Therefore, CP-OFDM can be used as the UL waveform for Msg3 transmission.

[0081] Figure 4 FIG. 1 illustrates a signaling diagram according to at least some example embodiments. Figure 1 UE 110 and radio network node 120. Time passes from top to bottom.

[0082] At step 410, the radio network node 120 may send a configuration to configure at least one repetition threshold to the UE 110, such threshold being associated with a beam and / or a number of repetitions (e.g., Msg1_beams_repetitions_thr and / or Msg1_number_of_repetitions_thr). For example, the radio network node 120 may send SSBs with different indices and configure the UE 110, for example, via SIB1 or a higher layer configuration (e.g., RRC).

[0083] At step 420, UE 110 may select a waveform for transmission of a connection request, such as Msg3 of a 4-step random access procedure. The waveform may be selected by UE 110 based on the number of repetitions (such as the number of beams or the number of repetitions) for transmissions with repeated random access preambles.

[0084] UE 110 may, for example, measure the RSRP of the received SSB and determine the best SSB beam. UE 110 may then determine the number of repetitions for sending the random access preamble, for example, in Msg1 of a 4-step random access procedure. In some example embodiments, UE 110 may determine the number of times Msg1 is repeated based at least on its beam capability and / or the measured RSRP. Thereafter, UE 110 may select a waveform for transmission of a connection request based on the determined number of repetitions for sending the random access preamble. The selection may also be based on one of the at least one repetition thresholds.

[0085] As another example, if the repetition threshold (e.g., Msg1_beams_repetitions_thr) associated with the beam is 4 and the number of beams for transmission with repeated random access preambles (e.g., Msg1 repetitions) is 2, the link budget may not be good enough, and therefore, UE 110 (such as a CE UE) may select a first waveform (e.g., DFT-s-OFDM) for transmission of a connection request, such as Msg1. In this case, UE 110 will be limited by its capabilities and cannot generate more than 2 beams with limited beamforming gain. However, if the number of beams for transmission with repeated random access preambles is equal to 8, it can be assumed that the link budget is good enough, and therefore, UE 110 may select a second waveform (e.g., CP-OFDM) for transmission of a connection request. In some example embodiments, UE 110 may ignore transform precoder parameters, such as the higher layer parameter msg3-transformPrecoder, after receiving the configuration in step 410.

[0086] As another example, if the repetition threshold (Msg1_number_of_repetitions_thr) associated with the number of repetitions is 4, and the UE 110 transmits the connection request with different transmit beams in 2 repetitions, the link budget may be good enough, and therefore the UE 110 may select the second waveform for the transmission of the connection request. In this case, the UE 110 may not be limited by its beamforming capabilities, and the UE 110 may be able to select multiple beams (and thus the antenna beamforming gain) based on the measured SS-RSRP. Therefore, if the number of selected beams is low (2 in this case), it means that not much gain is needed to meet the UL link budget. Therefore, the UE 110 does not need to use a more robust waveform (such as the first waveform, such as DFT-s-OFDM) for the transmission of the connection request. However, if the number of repetitions of the transmission of the random access preamble is equal to 8, it may be assumed that the link budget is not good enough, and therefore, the UE 110 may select the second waveform (such as CP-OFDM) for the transmission of the connection request.

[0087] Alternatively, if the repetition threshold associated with the beam (e.g., Msg1_beams_repetitions_thr) is 4 and the number of beams used for transmission with repeated random access preambles (e.g., Msg1 repetitions) is 8, the link budget may be good enough and, therefore, UE 110 may select a second waveform (e.g., CP-OFDM) for transmission of the connection request. In some example embodiments, UE 110 may ignore transform precoder parameters, such as the higher layer parameter msg3-transformPrecoder, after receiving the configuration at step 410.

[0088] As another example, if the repetition threshold (Msg1_number_of_repetitions_thr) associated with the number of repetitions is 4, and UE 110 uses a single (e.g., only one) transmit beam in 2 repetitions to transmit a connection request, the link budget may be good enough, and therefore, UE 110 may select the second waveform for transmission of the connection request. However, if the number of transmission repetitions of the random access preamble is equal to 8, it may be assumed that the link budget is not good enough, and therefore, UE 110 may select the first waveform for transmission of the connection request.

[0089] At step 430, UE 110 may send a random access preamble with repetitions to radio network node 120. For example, UE 110 may send multiple repetitions of the random access preamble, such as repetitions of Msg1, using (multiple) the same or different transmit beam configurations. That is, UE 110 may send Msg1 (PRACH) repetitions with or without beam sweeping. Radio network node 120 may schedule the transmission of a connection request after receiving the random access preamble repetitions. Radio network node 120 may, for example, decode Msg1 and schedule the transmission of Msg3.

[0090] At step 440, the radio network node 120 may send scheduling information for transmission of the connection request to the UE 110. The connection request may be repeatedly scheduled or non-repeatedly scheduled. The scheduling information may be sent via an uplink grant and carried by a random access response (such as Msg2 of a 4-step random access procedure). At step 450, the UE 110 may send the connection request using the selected waveform according to the scheduling information.

[0091] Thus, embodiments of the present invention enable switching of an uplink waveform to a first waveform, such as DFT-s-OFDM, based on at least one repetition threshold, wherein the at least one repetition threshold may include a number of repetitions and / or a number of beams for transmission of a random access preamble, such as a repetition of a Msg1 transmission. Thus, implicit uplink waveform switching for transmission of a connection request is enabled without additional dynamic signaling overhead. Furthermore, it is ensured that a robust waveform for transmission of a connection request may be selected when needed, for example based on a link budget that the UE 110 is expected to experience during transmissions with repeated random access preambles. In some example embodiments, a CE UE Msg1 transmission characteristic may be used as an indicator for UL waveform determination for Msg3 transmissions.

[0092] Figure 5An example apparatus capable of supporting at least some example embodiments is illustrated. Illustrated is a device 500, which may include, for example, a UE 110 or a wireless network node 120, or a control device configured to control its functions (possibly when installed therein). A processor 510 is included in the device 500, which may include, for example, a single-core or multi-core processor, wherein a single-core processor includes one processing core and a multi-core processor includes more than one processing core. The processor 510 may generally include a control device. The processor 510 may include more than one processor. The processor 510 may be a control device. For example, the processing core may include a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. The processor 510 may include at least one Qualcomm Snapdragon and / or Intel Atom processor. The processor 510 may include at least one application-specific integrated circuit ASIC. The processor 510 may include at least one field programmable gate array FPGA. The processor 510 may be a component for performing method steps in the device 500. The processor 510 may be configured at least in part by computer instructions to perform actions.

[0093] The processor may include, or be constructed as, a circuit system, which is configured to perform the various stages of the method according to the example embodiments described herein. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a pure hardware circuit implementation, such as an implementation in analog and / or digital circuitry only, and (b) a combination of hardware circuits and software, such as, where applicable: (i) a combination of (multiple) analog and / or digital hardware circuits with software / firmware, and (ii) any portion of (multiple) hardware processors with software (including (multiple) digital signal processors), software and (multiple) memories, which work together to enable a device such as a mobile phone or server to perform various functions), and (c) (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or portions of (multiple) microprocessors, which require software (e.g., firmware) to operate, but when software is not required for operation, the software may not be present.

[0094] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0095] Device 500 may include memory 520. Memory 520 may include random access memory and / or permanent memory. Memory 520 may include at least one RAM chip. Memory 520 may include, for example, solid-state, magnetic, optical and / or holographic memory. Memory 520 may be at least partially accessible by processor 510. Memory 520 may be at least partially included in processor 510. Memory 520 may be a component for storing information. Memory 520 may include computer instructions that processor 510 is configured to execute. When computer instructions configured to cause processor 510 to perform certain actions are stored in memory 520, and device 500 as a whole is configured to run under the guidance of processor 510 using computer instructions from memory 520, processor 510 and / or at least one of its processing cores may be considered to be configured to perform the certain actions. Memory 520 may be at least partially included in processor 510. Memory 520 may be at least partially located outside device 500, but device 500 may access the memory.

[0096] The device 500 may include a transmitter 530. The device 500 may include a receiver 540. The transmitter 530 and the receiver 540 may be configured to transmit and receive information, respectively, according to at least one cellular or non-cellular standard. The transmitter 530 may include more than one transmitter. The receiver 540 may include more than one receiver. The transmitter 530 and / or the receiver 540 may be configured to operate according to, for example, the Global System for Mobile Communications GSM, Wideband Code Division Multiple Access WCDMA, Long Term Evolution, LTE, and / or 5G / NR standards.

[0097] The device 500 may include a near field communication NFC transceiver 550. The NFC transceiver 550 may support at least one NFC technology, such as Bluetooth, Wibree, or similar technology.

[0098] Device 500 may include a user interface UI 560. UI 560 may include at least one of a display, a keyboard, a touch screen, a vibrator arranged to signal a user by vibrating device 500, a speaker, and a microphone. The user may be able to operate device 500 via UI 560, such as accepting an incoming call, making a phone call or a video call, browsing the Internet, managing digital files stored in memory 520 or on a cloud accessible via transmitter 530 and receiver 540 or via NFC transceiver 550, and / or playing games.

[0099] The device 500 may include or be arranged to accept a user identification module 570. The user identification module 570 may include, for example, a subscriber identification module SIM card that may be installed in the device 500. The user identification module 570 may include information identifying a subscription of a user of the device 500. The user identification module 570 may include cryptographic information that may be used to verify the identity of the user of the device 500 and / or facilitate encryption of communication information and billing of communications by the user of the device 500 via the device 500.

[0100] The processor 510 may be equipped with a transmitter that is arranged to output information from the processor 510 to other devices included in the device 500 via electrical conductors inside the device 500. Such a transmitter may include a serial bus transmitter that is arranged to output information to the memory 520 for storage therein, for example, via at least one electrical conductor. As an alternative to the serial bus, the transmitter may include a parallel bus transmitter. Similarly, the processor 510 may include a receiver that is arranged to receive information in the processor 510 from other devices included in the device 500 via electrical conductors inside the device 500. Such a receiver may include a serial bus receiver that is arranged to receive information from the receiver 540, for example, via at least one electrical conductor, for processing in the processor 510. As an alternative to the serial bus, the receiver may include a parallel bus receiver.

[0101] The device 500 may include Figure 5 Other devices not shown in the figure. For example, where the device 500 includes a smartphone, it may include at least one digital camera. Some devices 500 may include a rear camera and a front camera, wherein the rear camera may be used for digital photography and the front camera is used for video calls. The device 500 may include a fingerprint sensor that is arranged to at least partially authenticate a user of the device 500. In some example embodiments, the device 500 lacks at least one of the above devices. For example, some devices 500 may lack an NFC transceiver 550 and / or a user identification module 570.

[0102] Processor 510, memory 520, transmitter 530, receiver 540, NFC transceiver 550, UI 560 and / or user identification module 570 may be interconnected in a variety of different ways via electrical conductors within device 500. For example, each of the above devices may be individually connected to a main bus within device 500 to allow the devices to exchange information. However, those skilled in the art will appreciate that this is just an example, and that various ways of interconnecting at least two of the above devices may be selected according to example embodiments without departing from the scope of example embodiments.

[0103] Figure 6 1 is a flow chart of a first method according to at least some example embodiments. The apparatus of the first method may be UE 110 or a control device configured to control its functions (possibly when installed therein). That is, the steps of the first method may be performed by UE 110 or a control device configured to control its functions (possibly when installed therein).

[0104] The first method may include: at step 610, the device sends a random access preamble with repetitions to the wireless network node using a certain number of repetitions. The first method may also include: at step 620, the device selects a waveform for transmission of the connection request based on the number of repetitions and one of at least one repetition threshold. Finally, the first method may include: at step 630, the device sends the connection request to the wireless network node using the selected waveform.

[0105] It should be understood that the disclosed example embodiments are not limited to the specific structures, process steps or materials disclosed herein, but can be extended to equivalents that will be recognized by those skilled in the relevant art. It should also be understood that the terminology used herein is only used to describe specific example embodiments and is not intended to be limiting.

[0106] References throughout this specification to an exemplary embodiment or exemplary embodiments indicate that a particular feature, structure, or characteristic described in conjunction with the exemplary embodiment is included in at least one exemplary embodiment. Thus, the phrases "in an exemplary embodiment" or "in an exemplary embodiment" appearing in various places in this specification do not necessarily all refer to the same exemplary embodiment. When terms such as approximately or substantially are used to reference values, the exact value is also disclosed.

[0107] As used herein, for convenience, multiple items, structural elements, constituent elements and / or materials may be presented in a common list. However, these lists should be interpreted as each member in the list being individually identified as a separate and unique member. Therefore, any individual member in such a list should not be interpreted as the de facto equivalent of any other member in the same list simply based on its presentation in a common group (without an opposite indication). In addition, various example embodiments and examples and alternatives to its various components may be referenced herein. It should be understood that such example embodiments, examples and alternatives should not be interpreted as de facto equivalents to each other, but should be considered as separate and autonomous representations.

[0108] In an example embodiment, an apparatus such as UE 110 or radio network node 120 may include means for performing the above-described example embodiments and any combination thereof.

[0109] In an example embodiment, the computer program may be configured to produce a method according to the above example embodiments and any combination thereof. In an example embodiment, a computer program product embodied on a non-transitory computer readable medium may be configured to control a processor to perform a process including the above example embodiments and any combination thereof.

[0110] In an example embodiment, an apparatus such as UE 110 or radio network node 120 may include 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, together with the at least one processor, cause the apparatus to perform at least the above-described example embodiments and any combination thereof.

[0111] In addition, the described features, structures or characteristics can be combined in any suitable manner in one or more example embodiments. In the foregoing description, many specific details are provided, such as examples of length, width, shape, etc., to provide a thorough understanding of the example embodiments of the present disclosure. However, those skilled in the relevant art will recognize that the present disclosure can be practiced without one or more specific details, or practiced using other methods, components, materials, etc. In other cases, in order to avoid blurring aspects of the present disclosure, known structures, materials, or operations are not shown or described in detail.

[0112] Although the above examples illustrate the principles of the exemplary embodiments in one or more specific applications, it will be apparent to those skilled in the art that many modifications may be made to the form, usage and details of implementation without departing from the principles and concepts of the present disclosure without exercising creative ability. Therefore, the present disclosure is limited only by the following claims.

[0113] In this document, the verbs "to comprise" and "to include" are used as open limitations, neither excluding nor requiring the presence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of "a" or "an" (i.e., the singular) in this document does not exclude a plurality.

[0114] Industrial Applicability

[0115] At least some example embodiments find industrial application in cellular communication networks, such as in 3GPP networks.

[0116] List of abbreviations

[0117] 3GPP: Third Generation Partnership Project

[0118] CE: Coverage Enhancement

[0119] CP-OFDM: Cyclic Prefix Orthogonal Frequency Division

[0120] DCI: Downlink Control Information

[0121] DFT-S-OFDM: Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing

[0122] FDD: Frequency Division Duplex

[0123] GSM: Global System for Mobile Communications

[0124] IAB: Integrated Access and Backhaul

[0125] IoT: Internet of Things

[0126] LTE: Long Term Evolution

[0127] M2M: Machine to Machine

[0128] NFC: Near Field Communication

[0129] OFDM: Orthogonal Frequency Division Multiplexing

[0130] MIB: Master Information Block

[0131] MIMO: Multiple Input Multiple Output

[0132] PAPR: Peak to Average Power Ratio

[0133] PBCH: Physical Broadcast Channel

[0134] PRACH: Physical RACH

[0135] PUCCH: Physical Uplink Control Channel

[0136] PUSCH: Physical Uplink Shared Channel

[0137] RACH: Random Access Channel

[0138] RAT: Radio Access Technology

[0139] RRC: Radio Resource Control

[0140] RSRP: Reference Signal Received Power

[0141] SIB: System Information Block

[0142] SRS: Sounding Reference Signal

[0143] SS: Synchronous signal

[0144] SSB: Synchronization Signal Block

[0145] TRP: Transmission Reception Point

[0146] UE: User Equipment

[0147] UL: Uplink

[0148] UI: User Interface

[0149] WCDMA: Wideband Code Division Multiple Access

[0150] WiMAX: Worldwide Interoperability for Microwave Access

[0151] WLAN: Wireless Local Area Network

[0152] Reference numerals list

[0153] 110 UE 112、114 Beam 120 Wireless network node 125、135 Wired interface 130 Core Network 210-240 Figure 2 Steps in 410-450 Figure 4 Steps in 500-570 Figure 5 The structure of the device 610-630 Figure 6 The stages of the first method

Claims

1. A device comprising: - means for sending a random access preamble with repetitions to a radio network node using a certain number of repetitions; - means for selecting a waveform for transmission of a connection request based on said number of repetitions and one of at least one repetition threshold; as well as - means for sending said connection request to said wireless network node using said selected waveform.

2. The apparatus of claim 1, wherein the random access preamble is sent in a first message of a 4-step random access procedure, and the connection request is sent in a third message of the 4-step random access procedure.

3. The apparatus of any preceding claim, wherein the means for selecting the waveform further comprises: - means for comparing said number of repetitions with said one of said at least one repetition threshold; as well as - means for selecting said waveform for transmission of said connection request based on said comparison.

4. The apparatus of any preceding claim, wherein the means for selecting the waveform further comprises: - means for selecting a first waveform or a second waveform as said waveform for transmission of said connection request. The apparatus of claim 4 , wherein the first waveform is more robust than the second waveform.

6. The apparatus of claim 4 or 5, wherein the first waveform is discrete Fourier transform spread orthogonal frequency division DFT-s-OFDM, and the second waveform is cyclic prefix orthogonal frequency division CP-OFDM.

7. The apparatus according to any one of claims 4 to 6, wherein the one of the at least one repetition threshold and the number of repetitions is a beam number, and the apparatus further comprises: - means for selecting said first waveform when said number of repetitions is less than or equal to said one of said at least one repetition threshold; as well as - means for selecting said second waveform when said number of repetitions is greater than said one of said at least one repetition threshold.

8. The apparatus according to any one of claims 4 to 6, wherein the one repetition threshold of the at least one repetition threshold and the number of repetitions are the number of repetitions, and the apparatus further comprises: - means for selecting said second waveform when said number of repetitions is less than or equal to said one of said at least one repetition threshold; as well as - means for selecting said first waveform when said number of repetitions is greater than said one of said at least one repetition threshold.

9. The device according to any one of the preceding claims, further comprising: - means for receiving, from said radio network node, a configuration of said at least one repetition threshold configured for transmission of said random access preamble.

10. The apparatus according to claim 9, further comprising: - means for ignoring transformed precoder parameters for transmission of said connection request after receiving said configuration.

11. The device according to any of the preceding claims, wherein the repeat number is the Msg1 repeat number.

12. An apparatus comprising: - means for receiving a random access preamble with repetitions from a user equipment using a certain number of repetitions; - means for selecting a waveform for receipt of a connection request based on said number of repetitions and one of at least one repetition threshold; as well as - means for receiving said connection request from said user equipment using said selected waveform.

13. A method comprising: -sending, by the device, a random access preamble with repetitions to a wireless network node using a certain number of repetitions; - selecting, by the device, a waveform for transmission of a connection request based on the number of repetitions and one of at least one repetition threshold; as well as - sending, by the device, the connection request to the wireless network node using the selected waveform.

14. A method comprising: - receiving, by the device, a random access preamble with repetitions from a user equipment using a certain number of repetitions; - selecting, by the device, a waveform for receipt of a connection request based on the number of repetitions and one of at least one repetition threshold; as well as - receiving, by the apparatus, the connection request from the user equipment using the selected waveform.

15. A computer program comprising instructions which, when executed by an apparatus, cause the apparatus to perform the method according to claim 13 or 14.

Images