Random Access Procedure

Abstract

In an example embodiment of the present disclosure, an apparatus is provided comprising: means for obtaining one or more cell-specific indicators, the cell-specific indicators including configurations for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including a repetition setting for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; determining and selecting a sequence of ROs from the candidate sequences of ROs for transmission of the first message with repetition using the repetition setting RC; and using the selected sequence of ROs for transmission of the first message with repetition.

Description

[Technical Field]

[0001] Various exemplary embodiments relate to random access procedures for mobile networks. [Background technology]

[0002] This section is not an admission that any technology described herein represents the state of the art, but rather provides useful background information.

[0003] In mobile networks, random access procedures are used to initiate data transfers.

[0004] The present disclosure relates to the development of random access procedures, and more particularly to random access messages with repetition.

[0005] The scope of protection sought for various embodiments of the present disclosure is defined by the independent claims. To the extent that there are exemplary embodiments and features herein that do not fall within the scope of the independent claims, they are to be construed as examples useful for understanding various exemplary embodiments.

[0006] According to a first example aspect of the present disclosure, obtaining a cell-specific indicator, the cell-specific indicator including a configuration for an aspect of a random access procedure including transmission of a first message with repetition, the cell-specific indicator including a repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; determining and selecting, using the repetition setting, a sequence of the RO from among the candidate sequences of the RO for transmitting the first message with repetition; performing transmitting a first message with repetitions using the selected sequence of ROs; An apparatus is provided that includes means for performing the steps of:

[0007] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, determining and selecting a sequence of ROs is performed by using a repetition setting to determine candidate sequences of ROs for transmission of the first message with repetition, and selecting one of the determined candidate sequences of ROs.

[0008] In some exemplary embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, determining and selecting a sequence of ROs is performed by using an iterative setting to determine one or more candidates for a first RO in the sequence and selecting one of the candidates as the first RO in the sequence, and iteratively determining one or more subsequent candidates for a subsequent RO in the sequence based on a previously selected RO in the sequence and selecting one of the subsequent candidates as the subsequent RO in the sequence until the required number of ROs have been selected.

[0009] In some exemplary embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, when there are multiple ROs or sequences of ROs to select from, the selection is performed in a round-robin fashion.

[0010] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, selecting the sequence of ROs is performed entirely before the first transmission of the first message with repetitions.

[0011] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, selecting a sequence of ROs occurs simultaneously with the transmission of a first message with repetitions, and the repetitions of the first message are transmitted after selecting the ROs on which the repetitions are transmitted and before selecting the ROs for transmission of subsequent repetitions of the first message, if any.

[0012] In some example embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, the ROs in a selected sequence of ROs occupy different time resources.

[0013] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, one or more cell-specific indicators are received from the network.

[0014] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the apparatus of the first aspect is or is included in a user equipment.

[0015] According to a second exemplary embodiment of the present disclosure, defining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; providing the defined one or more cell-specific indicators to a user equipment (UE), and the UE determining and selecting a sequence of ROs from among the candidate sequences of ROs for transmission of the first message with repetition; An apparatus is provided that includes means for performing the steps of:

[0016] In some exemplary embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, the apparatus of the second aspect is a network element or is included in a network element. The network element may be, for example, a gNB. The network element may be a physical device or a virtual network function including, for example, one or more virtual machines (VMs) running on a virtualization platform including one or more virtual servers.

[0017] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the recurrence configuration groups multiple ROs at different frequency / time instances to form a candidate sequence of one or more ROs.

[0018] In some example embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, the iteration configuration comprises density parameters for generating one or more random sparse matrices for determining connections from one RO to a subsequent RO in a candidate sequence of ROs.

[0019] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the iteration configuration includes one or more sparse matrices that provide information about whether an RO is part of a candidate sequence of ROs.

[0020] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the recurrence configuration includes one or more combination indicators that provide a ranking of one or more combinations of ROs among all possible combinations of ROs, with one combination indicating a candidate sequence of one RO.

[0021] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the recurrence configuration includes a first binary sequence indicating a first RO of a candidate sequence of ROs and a second binary sequence indicating a group of ROs into which the remaining ROs of the candidate sequence of ROs are placed.

[0022] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the recurrence configuration includes N*M bits for each configured candidate sequence of ROs, where N is the number of ROs in the candidate sequence of ROs, and each group of M bits indicates one RO in each group of consecutive ROs.

[0023] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the candidate sequences of ROs have at least one of a first RO or a last RO in common, and the repeat configuration includes a single representation(s) of the common RO and sequence-specific representations of the other ROs in the candidate sequence of ROs.

[0024] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the one or more cell-specific indicators include a preamble configuration of multiple preambles for the transmission of the first message with repetition, from which the UE selects a preamble for the transmission of the first message with repetition.

[0025] In some example embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the one or more cell-specific indicators include a maximum time setting for the UE to determine a maximum time for transmission of the first message with repetition.

[0026] In some exemplary embodiments alone or in combination with other embodiments of different aspects of the present disclosure, the random access procedure is contention based random access (CBRA).

[0027] In some exemplary embodiments, alone or in combination with other embodiments of different aspects of the present disclosure, the means of the apparatus of the first aspect and / or the second aspect comprises at least one processor and at least one memory containing executable instructions that, when executed by the at least one processor, perform the operations of the apparatus.

[0028] According to a third exemplary aspect of the present disclosure, obtaining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; determining and selecting, using the repetition setting, a sequence of the RO from among the candidate sequences of the RO for transmitting the first message with repetition; transmitting a first message with repetitions using a selected sequence of ROs; A method is provided which includes:

[0029] According to a fourth exemplary aspect of the present disclosure, defining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; providing one or more defined cell-specific indicators to a user equipment (UE), for the UE to determine and select a sequence of ROs from among candidate sequences of ROs for transmission of a first message with repetition; A method is provided which includes:

[0030] According to a fifth exemplary aspect of the present disclosure, obtaining a cell-specific indicator, the cell-specific indicator including a configuration for an aspect of a random access procedure including transmission of a first message with repetition, the cell-specific indicator including a repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; determining and selecting, using the repetition setting, a sequence of the RO from among the candidate sequences of the RO for transmitting the first message with repetition; transmitting a first message with repetitions using a selected sequence of ROs; computer-executable program instructions are provided that are configured to cause at least the following to be performed:

[0031] According to a sixth exemplary aspect of the present disclosure, defining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; providing one or more defined cell-specific indicators to a user equipment (UE), for the UE to determine and select a sequence of ROs from among candidate sequences of ROs for transmission of a first message with repetition; computer-executable program instructions are provided that are configured to cause at least the following to be performed:

[0032] The computer program of the fifth and / or sixth aspects may be stored on a non-transitory computer-readable memory medium.

[0033] Any of the above-mentioned memory media may include digital data storage devices such as data disks or diskettes, optical storage devices, magnetic storage devices, holographic storage devices, magneto-optical storage devices, phase change memory, resistive random access memory, magnetic random access memory, solid electrolyte memory, ferroelectric random access memory, organic memory, or polymer memory. The memory media may be formed into a device that has no substantial function other than storing memory, or may be formed as part of a device that has other functions, including, but not limited to, a computer memory, a chipset, or a subassembly of an electronic device.

[0034] According to an aspect of a seventh embodiment of the present invention, there is provided a method for detecting a plurality of stimuli, the method comprising: obtaining a cell-specific indicator, the cell-specific indicator including a configuration for an aspect of a random access procedure including transmission of a first message with repetition, the cell-specific indicator including a repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; determining and selecting, using the repetition setting, a sequence of the RO from among the candidate sequences of the RO for transmitting the first message with repetition; transmitting a first message with repetitions using a selected sequence of ROs; and at least one memory storing instructions to cause the device to execute the

[0035] According to an aspect of an eighth embodiment of the present disclosure, there is provided at least one processor, and an apparatus, when executed by the processor, comprising: defining one or more cell-specific indicators, the cell-specific indicators including configurations for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configurations for determining one or more candidate sequences of random access channel (RACH) opportunities (ROs) for transmission of the first message with repetition; providing the UE with one or more defined cell-specific indicators, for the UE to determine and select a sequence of ROs from among candidate sequences of ROs for transmission of the first message with repetition; and at least one memory storing instructions to cause the device to execute the

[0036] Different non-binding exemplary aspects and embodiments of the present invention have been illustrated above. The above-described embodiments are merely used to describe selected aspects or steps that may be utilized in implementing the embodiments of the present disclosure. Some embodiments may be presented with reference to only certain exemplary aspects. It should be understood that corresponding embodiments may also be applied to other exemplary aspects. [Brief explanation of the drawings]

[0037] For a more complete understanding of exemplary embodiments of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [Figure 1] Figure 1 is a signaling diagram of the 5G NR four-step RACH procedure. [Figure 2] FIG. 2 shows an example of time domain resource determination for a RACH opportunity. [Figure 3] Figure 3 shows an example of SSB to RO mapping. [Figure 4] FIG. 4 shows a process flow chart of some example embodiments. [Figure 5] FIG. 5 shows a process flow chart of some example embodiments. [Figure 6]FIG. 6 shows a process flow chart of some example embodiments. [Figure 7] FIG. 7 lists some example embodiment alternatives. [Figure 8] FIG. 8 shows a graph of some examples of RO sequences. [Figure 9] FIG. 9 illustrates a random sparse matrix of an exemplary embodiment. [Figure 10A] FIG. 10A shows details of an exemplary embodiment. [Figure 10B] FIG. 10B shows details of an exemplary embodiment. [Figure 11] FIG. 11 is a block diagram of an exemplary embodiment of the device. DETAILED DESCRIPTION OF THE INVENTION

[0038] Exemplary embodiments of the present disclosure and their potential advantages are understood by reference to Figures 1-11 of the drawings, where like reference numbers refer to like parts or steps.

[0039] In the following, various exemplary embodiments of the present disclosure are described in detail in the context of 5G NR technology. However, it should be noted that various exemplary embodiments of the present disclosure may be applied to other mobile network and wireless communication technologies in addition to 5G NR as well (e.g., 6G technology or future technologies such as technologies subsequently developed).

[0040] 5G NR supports two contention-based random access (CBRA) procedures: a four-step random access channel (RACH) (Rel-15) and a two-step RACH (Rel-16). For purposes of illustration and simplicity, this disclosure focuses on a four-step RACH, although various exemplary embodiments of this disclosure are equally applicable to a two-step RACH.

[0041] Figure 1 is a signaling diagram of a 5G NR four-step RACH procedure, which shows a user equipment (UE) 101 and an NR Node B (gNB) 102. The messages of the four-step RACH procedure shown in Figure 1 can be summarized as follows: First message Msg1 (also known as PRACH): The UE 101 transmits a specific preamble to the gNB 102 via a physical random access channel (PRACH) using a specific resource called a RACH opportunity (RO). Second message Msg2 (aka RAR): The gNB102 replies with a Random Access Response (RAR) message containing the detected preamble ID, a time advance command, a temporary cell RNTI, a radio network temporary identifier (TC-RNTI), and an UL grant for the transmission of a third message Msg3 on the physical uplink shared channel (PUSCH). Third message Msg3 (RC request): The UE 101 responds to Msg2 on the scheduled PUSCH with an ID for contention resolution. Fourth message Msg4 (aka RRC setup): gNB102 sends a contention resolution message with a contention resolution ID.

[0042] Upon receiving Msg4, UE 101 sends an ACK on the PUCCH if Msg4 carries a contention resolution ID, completing the four-step RACH. It is worth noting that Msg1 is preceded by a preliminary step: transmission and reception of synchronization signal blocks (SSBs), i.e., DL beam sweeping, which is not formally part of the RACH procedure. As a result of this preliminary step, UE 101 selects the index of the preferred SSB beam and decodes the physical broadcast channel (PBCH) associated with the master information block (MIB), system information block (SIB), etc. This index is also used by the UE to identify the appropriate RO for preamble transmission (i.e., Msg1) according to the SSB-to-RO mapping implicitly conveyed by SIB1.

[0043] The two-step RACH is similar to the four-step RACH of FIG. 1, except that Msg1 and Msg3 are combined into MsgA and transmitted without waiting for intervening feedback from the network (i.e., Msg2 in FIG. 1). Similarly, the gNB combines Msg2 and Msg4 into MsgB. Various embodiments of the present disclosure may be similarly applied to Msg1 of FIG. 1, or the preamble / Msg1 portion of MsgA of the two-step RACH.

[0044] In the following, the configuration of RACH opportunities (ROs) will be described to facilitate understanding of various embodiments of the present disclosure.

[0045] The time domain resources for RACH are configured by higher layer signaling via prach-ConfigurationIndex (rach-ConfigGeneric), which serves as an indicator of a table row defined in 3GPP® specification TS38.211 V17.3.0 (item 6.3.3.2). The UE uses the parameters indicated by prach-ConfigurationIndex to determine the PRACH preamble format for locating the RO in the time domain as defined in the 3GPP® specification.

[0046] 2 shows an example of determining time domain resources for a RACH opportunity. In this embodiment, the prach-ConfigurationIndex is 251. With this index indicated, the UE determines: Preamble format C2 should be used. RO is n SFN System frame number (n) that satisfies mod 1=0 (i.e., all SFN numbers are valid) SFN ) Within each determined SFN, ROs are assigned to subframe numbers 2 and 7. Within each determined subframe, the remaining parameters in the considered row indicate that RO starts at symbol numbers 0, 6, 14, and 20. The symbol numbers are counted consecutively regardless of the number of slots in the subframe, which depends on the subcarrier spacing configured for the PRACH. The duration of the RO is 6 symbols (although the actual duration of the preamble format may be less).

[0047] Finally, the validity of the determined RO must be checked: if the RO is within a UL symbol or within a flexible symbol, and there is a sufficient gap after the last SSB / DL symbol, the RO is determined to be valid.

[0048] In the frequency domain, the parameters msg1-FrequencyStart and msg1-FDM configured in RACH-ConfigGeneric indicate the offset of the lowest RO in the frequency domain of a group of back-to-back OFDM symbols and the number of ROs multiplexed in the frequency domain, respectively. The number of occupied resource blocks (RBs) per RO, expressed as the number of RBs in PUSCH, is specified in the 3GPP® specifications depending on the configured preamble length and subcarrier spacing of PRACH and PUSCH.

[0049] The mapping of SSB indices to the determined ROs is necessary for the UE to understand which ROs are associated with the SSB indices selected in the preliminary phase before the RACH procedure begins. Since different SSB indices are beamformed in different directions within a cell, selecting an incorrect SSB index may cause the RACH procedure to fail.

[0050] For this purpose, the parameter ssb-perRACH-OccasionAndCB-PreamblesPerSSB is set in RACH-ConfigCommon. This parameter indicates (i) the number of SSB indices per RO and (ii) the number of contention-based preambles per SSB index. Once this information is provided to the UE, the UE maps the SSB index to the time-frequency grid of the RO (determined as described above) in the following order: frequency resource index, time resource index of the RO within the PRACH slot, and PRACH slot.

[0051] Figure 3 is a diagram showing an example of SSB-to-RO mapping. Figure 3 is a diagram showing an example of valid ROs in one frame determined as shown in Figure 2. As an additional configuration, assume a DDSUU slot structure, Msg1-FDM=2, and ssb-perRACH-OccasionAndCB-PreamblesPerSSB=1 / 2. Based on this configuration, two ROs are multiplexed in the frequency domain (Msg1-FDM=2), and any two FDM-multiplexed ROs are mapped to the same SSB index (ssb-perRACH-OccasionAndCB-PreamblesPerSSB=1 / 2).

[0052] The 4G LTE specification includes an Msg1 repetition (repeat) feature that ensures Msg1 transmission to achieve improved coverage. The inventors of the present disclosure have determined that the 4G LTE Msg1 repetition feature cannot be directly applied to 5G NR due to differences between LTE and NR systems with respect to the radio air interface. 5G NR is based on a beam-based architecture that relies heavily on analog and / or digital beamforming. This is not the case in LTE, where beam management is more rudimentary.

[0053] In the context of 5G NR, there are several challenges related to the Msg1 repetition feature. Considering a 5G NR scenario in which a gNB uses a fixed number of analog / digital beams to serve UEs and there is no specific limit on Msg1 repetition, Msg1 collisions may occur. In such a scenario, a CE UE consumes more time and energy to transmit multiple (e.g., four or eight) Msg1 repetitions compared to a single Msg1 transmission, resulting in a collision on the gNB side and the need to retransmit Msg1 only at the end. This time horizon becomes even longer when considering that UL slots are not always contiguous (e.g., in TDD systems) and multiple SSB indices (up to 64 in FR2) may be used in the network. Therefore, collisions in Msg1 repetitions can cause significant delays in initial access and should be avoided, especially for low-SNR CE UEs that perform Msg1 repetitions at the cell edge. Furthermore, it is not always possible to allocate completely independent resources (such as preambles and ROs) to multiple UEs that perform repetition of Msg1.

[0054] Furthermore, it should be noted that a temporary ID is assigned to a UE whose Msg1 transmission is detected only upon reception of Msg1 itself. Therefore, even if dedicated resources are configured for Msg1 repetition, the gNB has no effective means of distinguishing between two UEs repeating Msg1, since there are only cell-specific resources. This may prevent the gNB from coherently combining multiple Msg1s when multiple UEs attempt repeated access. This may degrade the performance of Msg1 transmissions and reduce the practicality of Msg1 repetition.

[0055] In the following, various embodiments of the present disclosure that provide an Msg1 repetition function suitable for 5G NR are described in detail. The solution is for the network to define one or more candidate sequences of ROs for the transmission of Msg1 with repetition. The UE can then select an RO sequence from the candidate sequences.

[0056] For simplicity and for the detailed disclosure of some exemplary embodiments, a group of back-to-back FDM symbols is defined as a time instance, ie, the duration of one RO in a slot.

[0057] Figure 4 shows a flowchart of a process of an example embodiment. This process can be implemented, for example, in a UE, such as the UE 101 of Figure 1, or in the device 1100 of Figure 11. The process includes the following steps:

[0058] Step 401: One or more cell-specific indicators are obtained. The cell-specific indicators include configurations for aspects of the RACH procedure including transmission of a first message with repetition. Furthermore, the cell-specific indicators include repetition configurations for determining one or more candidate sequences of ROs for transmission of the first message with repetition (Msg1). That is, the repetition configurations define one or more candidate sequences of ROs that a UE of each cell can select from.

[0059] Generally, the recurrence configuration groups multiple ROs from different frequency / time instances to form a candidate sequence for one or more ROs. The grouping is provided as a relationship between the configured ROs via the higher layer parameters prach-ConfigurationIndex and ssb-perRACH-OccasionAndCB-PreamblesPerSSB.

[0060] According to an exemplary embodiment, the candidate sequences of RO have the following properties: ROs that share the same time resource cannot belong to the same sequence. The ROs in the sequence are ordered by index (according to the specification), e.g., first by increasing frequency resource index, second by increasing time resource index, and third by increasing PRACH slot index. Sequences may overlap, i.e., the same RO may appear in multiple sequences. An RO that appears in multiple sequence candidates corresponds to a node in a graph with multiple incoming and outgoing edges. This feature provides a low collision probability with a minimal number of resources.

[0061] In an exemplary embodiment, the one or more cell-specific indicators may further include a preamble configuration of a plurality of preambles for transmission of the first message with repetition. The preamble configuration may be used by the UE to select a preamble for transmission of the first message with repetition. In an exemplary embodiment, the preamble for transmission of the first message with repetition may be part of a reserved set, i.e., not selected by UEs that do not perform transmission of the first message with repetition.

[0062] In an example embodiment, the one or more cell-specific indicators may further include a maximum time setting, which may be used by the UE to determine a maximum time for transmission of the first message with repetition. Details of an example implementation of the maximum time setting are provided later in this disclosure.

[0063] The cell-specific indicator can be provided to the UE by the network (e.g., gNB) by, for example, broadcasting or signaling this information within the respective cell. Such broadcasting or signaling can be performed prior to the proper RACH procedure, e.g., during transmission and reception of synchronization signal blocks (SSBs). The repetition configuration can be used by the UE together with the higher layer parameters prach-ConfigurationIndex and ssb-perRACH-OccasionAndCB-PreamblesPerSSB defined for the RACH procedure.

[0064] Step 402: The repetition setting is used to determine and select a sequence of ROs for transmitting the first message with repetition.

[0065] Step 402 can be performed by first determining candidate sequences for all ROs according to an iterative setting and then selecting one of the determined candidate sequences. Alternatively, an iterative process can be performed without completely determining all possible candidate sequences. In such an iterative process, one or more candidates for the first RO in the sequence are determined according to the iterative setting, and one of the candidates is selected. Next, subsequent ROs are repeatedly determined and selected until the required number of ROs has been selected. One or more subsequent candidates for the subsequent ROs in the sequence are determined based on the previously selected ROs, and one of the determined subsequent candidates is selected. In this way, the sequence of the selected RO is completely determined, while the other candidate sequences are not necessarily determined because they are not necessarily required. If there are multiple ROs or sequences of ROs to select, they can be selected in a round-robin manner.

[0066] Step 402 includes using the recurrence configuration in combination with the parameters prach-ConfigurationIndex and ssb-perRACH-OccasionAndCB-PreamblesPerSSB.

[0067] In an exemplary embodiment, multiple ROs in the selected sequence of ROs occupy different time resources.

[0068] Step 403: The selected sequence of ROs is used to transmit a first message involving a repetition of the RACH procedure.

[0069] It should be noted that the selection of the sequence of ROs may be performed entirely before the transmission of the first Msg1 repetition, i.e., the entire sequence of ROs to be used for the transmission of N Msg1 repetitions is determined and selected by the UE before the start of the Msg1 transmission with repetitions. Alternatively, the selection of the sequence of ROs may be performed simultaneously with the transmission of N Msg1 repetitions, i.e., the first Msg1 repetition may be transmitted immediately after the first RO of the sequence is selected (or before selecting the RO for the next Msg1 repetition, if there are more repetitions to transmit, or at least before selecting the entire sequence of ROs).

[0070] Figure 5 shows a flowchart of a process of an exemplary embodiment. This process can be implemented, for example, in a network element such as the gNB of Figure 1 or the device 1100 of Figure 11. The process includes the following steps:

[0071] Step 501: One or more cell-specific indicators are defined. The cell-specific indicators include configurations for aspects of a RACH procedure including transmission of a first message with repetition. Furthermore, the cell-specific indicators include repetition configurations for determining one or more candidate sequences of ROs for transmission of the first message with repetition. That is, defining the one or more cell-specific indicators includes defining one or more candidate sequences of ROs for selection by UEs of the respective cells.

[0072] In an exemplary embodiment, the one or more cell-specific indicators may further include a preamble configuration of multiple preambles for transmitting the first message with repetition, from which the UE selects a preamble for transmitting the first message with repetition.

[0073] In an exemplary embodiment, the one or more cell-specific indicators may further include a maximum time setting for the UE to determine a maximum time for transmission of the first message with repetition.

[0074] The maximum time configuration may be expressed as a function of the number of subframes, the number of system radio frames, the number of ROs, the number of OFDM symbols, and / or the PRACH configuration or association period.

[0075] In an exemplary embodiment, the repetition configuration is defined in combination with the parameters prach-ConfigurationIndex and ssb-perRACH-OccasionAndCB-PreamblesPerSSB defined for the RACH procedure.

[0076] There may be multiple repetition configurations within a cell. This is useful, for example, if multiple Msg1 repetition numbers (e.g., N=2 and N=4 repetitions) are supported within the cell, or to provide additional diversity when only one value of N is supported within the cell. The choice is up to the network, which may define one or more cell-specific parameters to cover all possible supported repetition numbers or to allow for high diversity in RO selection at the UE.

[0077] Step 502: One or more defined cell-specific indicators are provided to be used by UEs by broadcasting the one or more cell-specific indicators in the cell. UEs in the cell can then determine and select a sequence of ROs for transmitting a first message involving a repetition of the RACH procedure.

[0078] Figure 6 shows a flowchart of a process of an example embodiment. This process can be implemented, for example, in a UE, such as the UE 101 of Figure 1, or in the device 1100 of Figure 11. The process includes the following steps:

[0079] Step 601: One or more cell-specific indicators are obtained. The cell-specific indicators include settings for aspects of the RACH procedure including transmission of a first message with repetition. Furthermore, the cell-specific indicators include repetition settings for determining one or more candidate sequences of ROs for transmission of the first message with repetition. The cell-specific indicators may further include preamble settings and maximum time settings, as described in connection with step 401 of FIG. 4 and step 501 of FIG. 5.

[0080] Step 602: one or more cell-specific indicators are used to configure RACH resources for the transmission of a first message Msg1 with repetition; A candidate sequence of ROs that transmit Msg1 with N repetitions within a set maximum time; A preamble for transmitting Msg1 with N repetitions; Determine.

[0081] Step 603: It is checked whether there is one or more determined candidate sequences.

[0082] Step 604: If it is determined that there is one determined candidate sequence, the determined candidate sequence is selected, and N ROs of the selected sequence are used to transmit Msg1 by N repetitions.

[0083] Step 605: If it is concluded that there are multiple determined candidate sequences, it is checked whether all determined candidate sequences share the same first (or last) RO.

[0084] Step 606: If it is concluded that all the determined candidate sequences share the same first RO, the first RO common to all the determined sequences is selected.

[0085] Step 607: If it is concluded that all the determined candidate sequences do not share the same first RO, one of the determined ROs is selected as the first RO of the sequence. This selection can be performed in a round-robin manner. The selection mechanism can be defined in a cell-specific indicator or hard-coded in the specification. If the first RO is not selected in a round-robin manner, different UEs can be separated in the network, for example, by a transmission preamble.

[0086] Step 608: One of the next ROs that may follow the selected first RO is selected. The selection may be performed in a round-robin manner. The selection mechanism may be defined in a cell-specific indicator or hard-coded in the specification.

[0087] Step 609: It is checked whether N ROs have been selected. If it is determined that N ROs have not been selected yet, the process returns to step 608 to select the next RO.

[0088] Step 610: If it is determined that N ROs have been selected, N repetitions of transmitting Msg1 are performed using the sequence of the selected N ROs.

[0089] Figure 7 shows a graphical representation of some example candidate sequences of ROs. Each RO sequence is represented by a set of nodes connected by directed edges. The nodes are arranged in a matrix, with nodes in the same row sharing the same frequency resource and nodes in the same column sharing the same time resource. The index of the frequency resource occupied by a node increases from bottom to top, and the index of the time resource increases from left to right.

[0090] Three candidate sequences for RO are shown in Figure 7. 1. [RO#1 RO#6 RO#11 RO#13] 2. [RO#1 RO#6 RO#8 RO#13] 3. [RO#1 RO#4 RO#8 RO#13]

[0091] In the first embodiment, the UE receives a cell-specific indicator including the repetition configuration of candidate sequences in Fig. 7. Based on the repetition configuration, the UE completely determines the candidate sequences 1-3 for the three ROs, and selects one of the determined sequences, for example, 1.[RO#1 RO#6 RO#11 RO#13].

[0092] In a second embodiment, the UE receives a cell-specific indicator including the repetition configuration of candidate sequences in Figure 7. Here, instead of completely determining three sequences, the UE determines at least one complete sequence, which is the final selected sequence, as follows: The UE determines and selects RO#1. The UE determines between RO#4 and RO#6 and selects RO#6. The UE determines RO#8 and RO#11 and selects RO#11. The UE determines and selects RO#13, thereby selecting sequence 1. [RO#1 RO#6 RO#11 RO#13]

[0093] Figure 8 shows alternatives to the exemplary embodiment. Different alternatives are listed that can be used to communicate the recurrence configuration to the UE. Some of the listed options may be combined or used in parallel.

[0094] Alternative 801: The iteration configuration includes density parameters for generating one or more random sparse matrices for determining connections from one RO to a subsequent RO in a candidate sequence of ROs.

[0095] In this embodiment, the UE generates, based on the density parameter, one or more random sparse matrices or vectors from one RO that are associated with the same SSB index and provide connectivity to subsequent configured ROs within a configured maximum time for transmission of the first message with repetition.

[0096] A sparse matrix / vector is a matrix / vector of ones and zeros, where the density of ones (the number of ones out of the total number of entries) is equal to the configured density. To randomize the number of next ROs in the sequence (e.g., edges in Figure 7) for each RO in the sequence (or node in Figure 7), the sparse matrix / vector must be randomly generated with a seed that depends at least on the time and frequency resources occupied by the RO(s) in question. Furthermore, the seed may depend on the SSB index with which the RO is associated. To allow the network to more precisely control which ROs are included in which sequence, the network may also configure one or more cell-specific sets of seeds.

[0097] Figure 9 shows a random sparse matrix of an exemplary embodiment. The illustrated matrix is ​​16x16 in size, and the configuration density associated with 16 configured ROs (which may or may not be aligned in time and frequency as in Figure 7) that may be part of a sequence of ROs, as in Figure 7 (connected nodes are part of the same sequence), is equal to 6% (14 results across the 16x16 entries).

[0098] In the example of Figure 9, the bit corresponding to row 6 and column 11 is set to 1, indicating that RO#11 and RO#6 are currently connected. The same is true for the other ROs. Symmetrically, the bit corresponding to row 11, column 6 is also set to 1. Therefore, determining the RO in each sequence does not require displaying the entire matrix, but only the portion below or above its main diagonal 910.

[0099] Alternatively, instead of a sparse matrix, multiple sparse vectors can be generated to represent the next RO(s) in one or more sequences containing the considered RO at the next time instance, one for each RO in each sequence. In particular, for each considered RO in a sequence, the number of next ROs at the next time instance is equal to the minimum number of sequences containing the considered RO. In the example of FIG. 7, for each RO at a given time instance, there are four possible next RO candidates in the sequence, so a random sparse vector of length 4 and set density needs to be created for each RO in the sequence of ROs. In the example of FIG. 7, RO#1 is set with a density of 0.5 (two next ROs at the next time instance, i.e., RO#1 is included in at least two sequences), while RO#4 is set with a density of 0.25 (one next RO at the next time instance, i.e., RO#4 is included in at least one sequence).

[0100] In the embodiment, only one density value is set to generate a sparse matrix or vector. The density value varies depending on the total number of sequences the network wants to set and the number of overlaps between them (i.e., the same RO belongs to two or more sequences). Fewer or more bits are required when the maximum number of sequences containing the target RO is small or large. For example, in the case of a sparse matrix, if the matrix density is quantized in 10% steps (e.g., [10%, 20%, ... 100%]), 10 states need to be represented by density values, and a total of 4 bits are required to set them.

[0101] Alternative 802: The iteration configuration includes one or more sparse matrices that provide information on whether an RO is part of a candidate sequence of multiple ROs.

[0102] In this embodiment, the repetition configuration is provided in the form of a sparse matrix or vector that provides information on whether the RO is part of a sequence. This information is provided, if applicable, for each configured RO associated with the same SSB index and within the configured maximum time for transmission of the first message with repetition, regardless of whether the RO is actually part of a sequence or not. The interpretation of the configuration is the same as in alternative 801.

[0103] Considering that only half of the matrix is ​​needed to represent all configured sequences, for 16 configured ROs associated with the same SSB index, a total of 128 bits are needed within the configured maximum time (16*16 / 2) for transmitting the first message with repetitions.

[0104] This approach requires more bits than the 801 alternative, but has the advantage of potentially allowing full control over connections between multiple ROs through recursive configuration.

[0105] Alternative 803: The recurrence configuration includes one or more combination indicators providing a ranking of one or more combinations of ROs among all possible RO combinations of a candidate sequence of ROs, one combination of ROs indicating one candidate sequence of ROs.

[0106] In this embodiment, among K consecutive ROs associated with the same SSB beam, each sequence of N ROs (for transmitting the first message in N repetitions) is ordered according to its index (determined according to the specification). A combination indicator provides the ranking of one combination for transmitting the first message in N repetitions among all possible combinations of N ROs among K ROs. One combination indicator is

number

number

[0107] In the example of Figure 7, three sequences of four nodes / ROs out of 16 are represented (and therefore configured in the UE), which requires only 33 bits.

[0108] Alternative 804: The recurrence configuration includes a first binary sequence indicating a first RO of a candidate sequence of ROs and a second binary sequence indicating a group of ROs into which the remaining ROs of the candidate sequence of ROs are placed.

[0109] In this embodiment, K consecutive ROs associated with the same SSB beam are ordered according to their index (determined according to the specification) and consist of up to F consecutive ROs.

number

number

[0110] 10A-10B show details of an alternative exemplary embodiment of 804. FIG.

[0111] Example of Figure 10A: The number of ROs in a group of consecutive ROs is 4 (i.e., F=4). That is, to represent each RO in each group of F=4 consecutive ROs,

number

[0112] Example of FIG. 10B: The number of ROs in a group of consecutive ROs is 4 (i.e., F=4), i.e., to represent each RO in each group of F=4 consecutive ROs,

number

number

number

[0113] Alternative 805: The repetition configuration includes N*M bits for each configured candidate sequence of ROs, where N is the number of ROs in the candidate sequence of ROs, and each group of M bits indicates one RO in each group of consecutive ROs.

[0114] In this embodiment, the network uses N*M bits to represent each sequence of N ROs;

number

[0115] An alternative example of 805 is described below. In the scenario of FIG. 7, N=4,

number

number

[0116] Alternative 805 is particularly useful when the number of ROs in the same time instance is greater than one.

[0117] Alternative 806: The candidate sequence of ROs have a first and / or last RO in common, and the repeat configuration includes a single representation of the common RO and sequence-specific representations of the other ROs in the candidate sequence of ROs.

[0118] In this embodiment, all sequences of N ROs share the same first and / or last RO, and such ROs are displayed only once, and only ROs other than such common ROs are displayed via indicators in each sequence.

[0119] An alternative example of 805 is described below. In Figure 7, all sequences of ROs share the same first and last ROs, both associated with the binary sequence 10. The network requires 4 bits to indicate the two common ROs and 4 bits to indicate the remaining ROs in each sequence of ROs. Thus, the network need only indicate the following sequences (which may be in a different order):

[10] ,

[10] , 0100, 0111, 1111 to indicate the two common ROs, totaling 16 bits for the remaining ROs in all sequences.

[0120] Other examples of alternative 805 are described below. In Figure 10A, all sequences of ROs share the same first RO associated with the binary sequence 10. The network requires two bits to indicate the common RO and six bits to indicate the remaining ROs for each sequence of ROs. Thus, the network only requires the following sequences (which may be in a different order) to indicate the first common RO:

[10] , [00 01 00], [00 10 00], [00 01 11], [00 10 11], [11 01 00], [11 01 11], [11 10 00], [11 10 11], to indicate the remaining ROs for all sequences, for a total of 50 bits.

[0121] 11 is a block diagram of an apparatus 1100 according to an example embodiment. The apparatus 1100 can operate as a network element, such as the gNB 102 of FIG. 1, or as a UE, such as the UE 101 of FIG. 1. The apparatus 1100 generally comprises a memory 1140 including computer program code 1150. The apparatus 1100 further comprises a processor 1120 for controlling operation of the apparatus 1100 using the computer program code 1150, and a communication unit 1110 for communicating with other nodes. Furthermore, the apparatus 1100 can comprise a user interface unit 1130.

[0122] The communication unit 1110 may include, for example, one or more of a local area network (LAN) port, a wireless local area network (WLAN) unit, a Bluetooth unit, a cellular data communication unit, or a satellite data communication unit. The communication interface 1110 may support one or more different communication technologies. The communication interface 1110 may support Ethernet communication and / or IP-based communication. The device 1100 may also include one or more communication interfaces 1110. The processor 1120 may include, for example, one or more of a master control unit (MCU), a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array, and a microcontroller. The user interface unit 1130 may include circuitry for receiving input from a user of the device 1100, for example, via a keyboard, a graphical user interface on a display, a voice recognition circuit, or an attached device such as a headset, and circuitry for providing output to the user, for example, via a graphical user interface or a speaker. Memory and storage may be expanded for capacity and / or redundancy purposes. Similarly, processing and / or communications may be implemented using multiple parallel or multiple components for capacity and / or redundancy purposes.

[0123] The computer program code 1150 can control the apparatus 1100 to perform one or more example embodiments of the present disclosure, such as the steps of Figures 4-6 and further details described in connection with Figures 7-9 and Figures 10A-10B.

[0124] As used herein, the term "circuit" means (a) hardware-only circuit implementations (e.g., analog and / or digital-only implementations); (b) a combination of hardware circuitry and software (if applicable); (i) any combination of analog and / or digital hardware circuitry and software / firmware; (ii) software (including digital signal processors), hardware processor portions with software and memory that cooperate to cause a device, such as a mobile phone or server, to perform various functions; (c) A hardware circuit or processor, such as a microprocessor or part of a microprocessor, that requires software (e.g., firmware) to operate, but the software may be absent when not required for operation; It may refer to one or more, or all, of the following:

[0125] This definition of circuit applies to all uses of the term in this application, including any claims. As a further example, as used herein, the term circuit also covers simply a hardware circuit or processor (or processors) or part of a hardware circuit or processor and its (or their) accompanying software and / or firmware implementation. The term circuit also covers, for example, a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network equipment, or other computing device or network equipment, if applicable to particular claim elements.

[0126] Without limiting the scope, interpretation, or application of the claims that follow, one or more technical effects of the example embodiments disclosed herein are an improved random access procedure. Another technical effect of the example embodiments disclosed herein is to provide details of a random access procedure suitable for 5G NR. More specifically, various embodiments provide for the configuration and determination of RACH resources for Msg1 repetition in a manner suitable for 5G NR.

[0127] Yet another technical effect of one or more exemplary embodiments disclosed herein is that the probability of collisions between UEs in poor coverage areas that perform Msg1 repetition may be reduced. Yet another technical effect of one or more exemplary embodiments disclosed herein is that the detection complexity at the receiver (to distinguish between UEs) may be reduced, for example, compared to a system in which there is no structured approach to RO determination and selection and the UE can randomly select an RO. Various exemplary embodiments provide that the number of blind decoding instances may be fewer than in some other approaches. Yet another technical effect of one or more exemplary embodiments in this example is that the practical usability of the Msg1 repetition function may be improved. Yet another technical effect of one or more exemplary embodiments disclosed herein is that the amount of resources required for Msg1 repetition is not excessively increased.

[0128] Embodiments of the present disclosure may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside, for example, on the gNB 102 or the UE 101. In exemplary embodiments, the application logic, software, or instruction set is maintained on any one of various conventional computer-readable media. A "computer-readable medium" in this example may be any non-transitory medium or means capable of storing, storing, communicating, propagating, or transporting instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, an example of which is illustrated and depicted in FIG. 11. A computer-readable medium may constitute a computer-readable storage medium, which may be any medium or means capable of storing or storing instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0129] If desired, different functions described herein may be performed in different orders and / or concurrently with one another. Furthermore, if desired, one or more of the functions described above may be optional or combined.

[0130] Various aspects of the disclosure are set out in the independent claims, but other aspects include other combinations of features of the described embodiments and / or dependent claims with features of the independent claims, and not just the combinations explicitly set out in the claims.

[0131] It should also be noted that while exemplary embodiments have been described hereinabove, these descriptions should not be construed in a limiting sense. Rather, there are several variations and modifications that can be made without departing from the scope of the present disclosure, as defined in the appended claims.

[0132] List of Abbreviations UE User Equipment gNB NR Node B Msg1 Message 1 PRACH Physical Random Access Channel RACH Random Access Channel RO RACH Opportunity FDM Frequency Domain Multiplexing SS / PBCH Synchronization Signal / Physical Broadcast Channel SSB sync signal block FR1 Frequency Range 1 FR2 Frequency Range 2 SIB1 System Information Block 1 TDD Time Division Duplex FDD Frequency Division Duplex OFDM Orthogonal Frequency Division Multiplexing Enhanced CE coverage

Claims

1. obtaining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; using the repetition configuration to determine and select a sequence of ROs from among the candidate sequences of ROs for transmitting the first message with repetition; using the selected sequence of ROs for transmitting the first message with repetition; An apparatus comprising: means for performing

2. Determining and selecting the sequence of ROs includes: determining a candidate sequence of the ROs for transmission of the first message with the repetition using the repetition configuration; selecting one of the determined candidate sequences of RO; The apparatus of claim 1 , wherein the apparatus is executed by:

3. Determining and selecting the sequence of ROs includes: determining one or more candidates for a first RO of the sequence using the iteration configuration, and selecting one of the candidates as the first RO of the sequence; iteratively determining one or more candidates for a subsequent RO of the sequence based on a previously selected RO of the sequence, and selecting one of the subsequent candidates as the subsequent RO of the sequence until a required number of ROs have been selected; The apparatus of claim 1 , wherein the apparatus is executed by:

4. 4. The apparatus of claim 1, wherein if there are multiple ROs or sequences of ROs to select from, the selection is performed in a round-robin fashion.

5. 5. The device according to claim 1, wherein the selection of the sequence of ROs is performed entirely before the first transmission of the first message with repetitions.

6. 5. The apparatus of claim 1, wherein selecting the sequence of ROs is performed simultaneously with the transmission of a first message with the repetitions, and wherein a repetition of the first message is transmitted after selecting the ROs on which that repetition is transmitted and before selecting the ROs for the transmission of subsequent repetitions, if any, of the first message.

7. The apparatus of claim 1 , wherein the ROs of the selected sequence of ROs occupy different time resources.

8. The apparatus of claim 1 , wherein the one or more cell-specific indicators are received from a network.

9. The device according to any one of claims 1 to 8, wherein the device is or is included in a user equipment.

10. defining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; providing the one or more defined cell-specific indicators to a user equipment (UE), wherein the UE determines and selects a sequence of ROs from among the candidate sequences of ROs for transmitting the first message with repetition; An apparatus comprising: means for performing

11. The apparatus of claim 10 , wherein the apparatus is or is contained within a network element.

12. The apparatus of claim 1 , wherein the repetition configuration groups multiple ROs of different frequency / time instances to form a candidate sequence of the one or more ROs.

13. 13. The apparatus of claim 1, wherein the iteration configuration includes a density parameter for generating one or more random sparse matrices for determining connections from one RO to a subsequent RO in the candidate sequence of ROs.

14. The apparatus of claim 1 , wherein the iteration configuration comprises one or more sparse matrices that provide information about whether an RO is part of a candidate sequence of ROs.

15. 13. The apparatus of claim 1, wherein the repetition configuration comprises one or more combination indicators providing a ranking of one or more combinations of ROs among all possible combinations of ROs, one combination indicating one candidate sequence of ROs.

16. 13. The apparatus of claim 1, wherein the repetition configuration comprises a first binary sequence indicating the first RO of the candidate sequence of ROs and a second binary sequence indicating a group of ROs in which the remaining ROs of the candidate sequence of ROs are located.

17. 13. The apparatus of claim 1, wherein the repetition configuration comprises N*M bits for each candidate sequence of configured ROs, where N is the number of ROs in the candidate sequence of ROs, and each group of M bits indicates one RO in each group of consecutive ROs.

18. 13. The apparatus of claim 1, wherein a plurality of the candidate sequences of ROs have at least one of the first RO or the last RO in common, and the repetition configuration includes a single representation of the common RO and sequence-specific representations of other ROs in the candidate sequences of ROs.

19. 19. The apparatus of claim 1, wherein the one or more cell-specific indicators include a preamble configuration of a plurality of preambles for the transmission of the first message with repetition, and wherein a UE selects a preamble for the transmission of the first message with repetition.

20. 20. The apparatus according to claim 1, wherein the one or more cell-specific indicators comprise a maximum time setting for a UE to determine a maximum time for transmission of the first message with repetition.

21. 21. The apparatus of claim 1, wherein the random access procedure is a contention-based random access (CBRA).

22. 22. Apparatus according to any preceding claim, wherein said means comprises at least one processor and at least one memory containing executable instructions that, when executed by said at least one processor, perform operations of said apparatus.

23. obtaining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; using the repetition configuration to determine and select a sequence of ROs from among the candidate sequences of ROs for transmitting the first message with repetition; transmitting a first message with repetitions using the selected sequence of ROs; A method comprising:

24. obtaining one or more cell-specific indicators, the cell-specific indicators including configuration for aspects of a random access procedure including transmission of a first message with repetition, the cell-specific indicators including repetition configuration for determining one or more candidate sequences of Random Access Channel (RACH) Opportunities (ROs) for transmission of the first message with repetition; using the repetition configuration to determine and select a sequence of ROs from among the candidate sequences of ROs for transmitting the first message with repetition; transmitting a first message with repetitions using the selected sequence of ROs; A computer program that stores instructions for executing at least the following:

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