UE assisted learning for prach receiver optimization

Abstract

An apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine at least one metric related to a first message of a random access procedure; transmit, to a network entity, the first message of the random access procedure; determine that a complying second message of the random access procedure was not received from the network entity; and transmit, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

Description

UE Assisted Learning For PRACH Receiver OptimizationRELATED APPLICATION

[0001] This application claims priority to IN Provisional Application No. 202441021077 filed March 20, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The examples and non-limiting example embodiments relate generally to communications and, more particularly, to UE assisted learning for PRACH receiver optimization.BACKGROUND

[0003] It is known for a communication device to gain access to a communication network via an access network node.SUMMARY

[0004] In accordance with an aspect, an apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine at least one metric related to a first message of a random access procedure; transmit, to a network entity, the first message of the random access procedure; determine that a complying second message of the random access procedure was not received from the network entity; and transmit, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

[0005] In accordance with an aspect, an apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a user equipment, information related to the apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complyingsecond message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

[0006] In accordance with an aspect, a method includes determining at least one metric related to a first message of a random access procedure; transmitting, to a network entity, the first message of the random access procedure; determining that a complying second message of the random access procedure was not received from the network entity; and transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

[0007] In accordance with an aspect, a method includes receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings.

[0009] FIG. 1 is a block diagram of one possible and non-limiting system in which the example embodiments may be practiced.

[0010] FIG. 2 illustrates a sequence of operations according to a first method described herein.

[0011] FIG. 3 illustrates a sequence of operations according to a second method described herein.

[0012] FIG. 4 illustrates a sequence of operations according to a third method described herein.

[0013] FIG. 5 is an example apparatus configured to implement the examples described herein.

[0014] FIG. 6 shows a representation of an example of non-volatile memory media used to store instructions that implement the examples described herein.

[0015] FIG. 7 is an example method, based on the examples described herein.

[0016] FIG. 8 is an example method, based on the examples described herein.

[0017] FIG. 9 is an example method, based on the examples described herein.

[0018] FIG. 10 is an example method, based on the examples described herein.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0019] Turning to FIG. 1, this figure shows a block diagram of one possible and nonlimiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of FIG. 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and / or 140- 2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0020] The RAN node 170 in this example is a base station that provides access for wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface (such as connection 131) to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface (such as connection 131) to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU 195 may include or be coupled to and control a radio unit (RU). The gNB-CU 196 is a logical node hosting radio resource control (RRC), SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that control the operation of one or more gNB-DUs. The gNB-CU 196 terminates the Fl interface connected with the gNB-DU 195. The Fl interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB- DU 195. The gNB-DU 195 is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU 196. One gNB-CU 196 supports one or multiple cells. One cell may be supported with one gNB-DU 195, or one cell may be supported / shared with multiple DUs under RAN sharing. The gNB-DU 195 terminates the Fl interface 198 connected with the gNB-CU 196. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

[0021] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 areconnected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, one or more memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and processor(s), and / or other hardware, but these are not shown.

[0022] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and / or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 150 may be implemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0023] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0024] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH / DU 195, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU 196) of the RAN node 170 to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0025] A RAN node / gNB can comprise one or more TRPs to which the methods describedherein may be applied. FIG. 1 shows that the RAN node 170 comprises TRP 51 and TRP 52, in addition to the TRP represented by transceiver 160. Similar to transceiver 160, TRP 51 and TRP 52 may each include a transmitter and a receiver. The RAN node 170 may host or comprise other TRPs not shown in FIG. 1.

[0026] A relay node in NR is called an integrated access and backhaul node. A mobile termination part of the IAB node facilitates the backhaul (parent link) connection. In other words, the mobile termination part comprises the functionality which carries UE functionalities. The distributed unit part of the IAB node facilitates the so called access link (child link) connections (i.e. for access link UEs, and backhaul for other IAB nodes, in the case of multi-hop IAB). In other words, the distributed unit part is responsible for certain base station functionalities. The IAB scenario may follow the so called split architecture, where the central unit hosts the higher layer protocols to the UE and terminates the control plane and user plane interfaces to the 5G core network.

[0027] It is noted that the description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell may perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0028] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and / or a data communications network (e.g., the Internet). Such core network functionality for 5G may include location management functions (LMF(s)) and / or access and mobility management function(s) (AMF(S)) and / or user plane functions (UPF(s)) and / or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (mobility management entity) / SGW (serving gateway) functionality. Such core network functionality may include SON (self- organizing / optimizing network) functionality. These are merely example functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to the network element 190. Thelink 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / W I / F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. Computer program code 173 may include SON and / or MRO functionality 172.

[0029] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, or a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0030] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transitory memory, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as nonlimiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, network element(s) 190, and other functions as described herein.

[0031] In general, the various example embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communicationcapabilities, music storage and playback devices having wireless communication capabilities, internet appliances including those permitting wireless internet access and browsing, tablets with wireless communication capabilities, head mounted displays such as those that implement virtual / augmented / mixed reality, as well as portable units or terminals that incorporate combinations of such functions. The UE 110 can also be a vehicle such as a car, or a UE mounted in a vehicle, a UAV such as e.g. a drone, or a UE mounted in a UAV. The user equipment 110 may be terminal device, such as mobile phone, mobile device, sensor device etc., the terminal device being a device used by the user or not used by the user.

[0032] UE 110, RAN node 170, and / or network element(s) 190, (and associated memories, computer program code and modules) may be configured to implement (e.g. in part) the methods described herein. Thus, computer program code 123, module 140-1, module 140-2, and other elements / features shown in FIG. 1 of UE 110 may implement user equipment related aspects of the examples described herein. Similarly, computer program code 153, module 150-1, module 150-2, and other elements / features shown in FIG. 1 of RAN node 170 may implement gNB / TRP related aspects of the examples described herein. Computer program code 173 and other elements / features shown in FIG. 1 of network element(s) 190 may be configured to implement network element related aspects of the examples described herein.

[0033] Having thus introduced a suitable but non-limiting technical context for the practice of the example embodiments, the example embodiments are now described with greater specificity.

[0034] The PRACH sequence design as standardized in 3GPP naturally evokes a correlation-based receiver design as it offers a balance between complexity and performance that is difficult to attain otherwise. In gNB, the PRACH detector calculates correlation energies for the samples defined by each cyclic shift window. The detection threshold is calculated from the predefined coefficient and the estimated noise (samples that are inferior to the predefined threshold are considered as noise samples). A preamble is detected when the correlation energy exceeds the detection threshold. The tighter (higher) predefined threshold can provide better ghost filtering capability, but it increases the missed detection rate (it limits the coverage). Moreover, a fixed predefined threshold does not work for all network conditions.

[0035] PRACH Success Rate (SR) is a major network KPI monitored closely by customers and is expected to be close to 100 percent. SR refers to the ratio of the total number of successful Msg3 to the detected Msg Is. Poor SR can lead to unnecessary radio resource allocations (PDCCH, Msg2 and PUSCH for Msg3) and introduce interference to the network. In addition, Msg3 HW / SW resources are allocated for each detected Msgls.

[0036] The main contributor to poor SR is often the ghost preambles (also known as false alarms) which are obtained as a by-product of the Msgl detection algorithms used by the gNB. Where a ghost preamble is referred to as an invalid preamble that a UE does not transmit. The higher number of invalid preambles causes a reduction in the SR.

[0037] A Mean Absolute Deviation (MAD) based detector may be defined by upper and lower bound thresholds (say T1 and TN). The thresholds defining the boundaries are precalculated for a given PRACH configuration. The detector calculates the detection threshold using the slot-level measurements of noise, interference, mean absolute deviation value, and the predefined thresholds defining the boundaries. The calculated detection threshold is bound below by T1 and bound above by TN. Theoretically and analytically, the robustness of the MAD algorithm as a statistical measure of deviation is predicated on a number of assumptions relating to the distribution characteristics of the underlying physical phenomena. If any typical assumption is violated, the MAD performance may degrade and become problematic. Furthermore, factors such as limited sample size, sampling error and estimation bias inherently constrain the reliability of statistical methods including and beyond the MAD algorithm. On the practical side, the current MAD implementation with manual tuning generalizes very poorly across different networks and inevitably introduces coupling across operators thus making tuning a highly complex and intricate process. In order to guide the current manual tuning process, all relevant information, e.g., link level measurements from gNB and UE logs, KPI reports, is exploited to infer a direction of tuning.

[0038] The nondeterministic nature of the radio environment necessitates a receiver design which adapts and evolves overtime in a guided manner. Thus, as a next evolution, the goal is to automate the process with possible enhancements. Related to this goal is to estimate the characteristics of the initial BWP (noise, interference, etc.) using UL measurements performed over some observation period. The detector is not adapted instantaneously (every PRACH slot) using the slot level measurements. To help the automation process (e.g. to confirm if our adaptation goes in the desired direction) additional input from the network KPIis also used, and SR is chosen for this purpose, e.g. a positive trend in SR KPI indicates that progress is being made in the desired direction.

[0039] An additional metric of interest is the so called missed RAPID (preamble ID) rate at the UE, which measures how often the UE does not receive a RAR carrying the RAPID associated to the preamble used by UE for the Msgl transmission, following the Msgl transmission itself. This metric refers to the ratio of (i-ii): i) The number of DO receptions through a PDCCH whose CRC is scrambled with the RA-RNTI corresponding to the RO over which the UE transmitted the PRACH preamble and the RAR payload carried by the PDSCH scheduled by such DO carries a RAPID that does not correspond to the preamble used by UE for the PRACH transmission, plus ii) the number of times in which the UE does not detect any PDCCH carrying a DO whose CRC is scrambled with the RA-RNTI corresponding to the RO over which the UE transmitted the PRACH preamble, where i) and ii) are over the total number of transmitted PRACH preambles. In other words, it is calculated as 1 — PT, where P1=probability for the UE to receive a DO through PDCCH whose CRC is scrambled with the RA-RNTI corresponding to the RO over which the UE transmitted the PRACH preamble, and the RAR payload carried by the PDSCH scheduled by such DO carries a RAPID corresponding to the preamble used by UE for the PRACH transmission.

[0040] The UEInformationResponse message is sent by the UE in the context of SON. This message includes the number of preambles sent by MAC for the last successfully completed random access procedure and whether contention is detected by MAC for at least one of the transmitted preambles for the last successfully completed random access procedure. This message cannot provide sufficient information to improve the performance of the automatic detector adaptation.

[0041] Unfortunately, the SR alone is not enough to supervise the learning. For example, an increase in SR can tell that the ratio of successful Msg3 to Msgl is increased but it cannot tell if the change occurs only because of filtering the Msgl ghosts without blocking any genuine preambles (i.e., missed detection at gNB). If the genuine preambles are blocked by these adaptation steps, then the process must be stopped or redirected. Currently, there are no possibilities to know the PRACH failure reasons.

[0042] Described herein are three methods to obtain the information related to misdetection of preamble at RACH receiver and additional information available at UE that can be usedfor PRACH receiver optimization. This can help balancing receiver performance between success-rate for Msg3 at BS and missed RAPID rate at the UE. It is worth noting that Method 1 and 2 convey the same additional elements to the gNB, while using different messages / signaling to this end. Such elements are (the order in which they are included in the corresponding payload does not matter) (1-3):

[0043] 1) Number of retransmissions due to missed RAPID at the UE (Number of retransmissions due to non-reception of RAR or reception of RAR not carrying the RAPID corresponding to the PRACH preamble transmitted by the UE).

[0044] 2) Initial PRACH TX power applied for first RACH attempt.

[0045] 3) According to some embodiments of the examples described herein, at least one of the following is also included (i-iv): i) The list of RSRP and RSRQ measured by the UE before the failed PRACH transmissions, ii) RSRP and RSRQ measured by the UE before the first failed PRACH transmission, iii) RSRP and RSRQ measured by the UE before the last failed PRACH transmission, iv) Average RSRP and RSRQ measured by UE before all the failed PRACH transmissions in this RACH attempt.

[0046] The metrics or information transmitted from the UE 110 to the gNB 170 (number of retransmissions, initial transmission power, RSRP or RSRQ measurements) may be determined by the UE 110 before or after the UE 110 transmits a first message of a random access procedure to the gNB 170, such as before or after message 202, message 302, or message 402.

[0047] Method 1: Including one or more of the elements above in the UEInformationResponse message the UE sends in response to the UEInformationRequest message. According to an embodiment of this method, suitable additional fields for requesting the above information can be added to the UEInformationRequest message.

[0048] Method 2: Including one or more of the elements above in the Msg3 payload. According to an embodiment of this method, suitable additional bit(s) / field(s) for requesting UE to include such elements in Msg3 payload can be added to RAR / Msg2 / UL grant payload.

[0049] Method 3 : Enhanced Msgl transmission to differentiate RACH failures due to missing RAR reception from other RACH failures, including Option 1 and Option 2:

[0050] Option 1. The preambles used for initial and re-transmissions follow pattern that helps BS to identify whether received preamble is retransmission or not. According to one embodiment this is achieved by having the UE choose the RO for the retransmission according to a hopping pattern associated to the RAR missing event. The hopping pattern can be hardcoded in the specification. The hopping pattern can be configured per cell via higher layer signaling, e.g., SIB1. According to another embodiment this is achieved by having the UE picking a different preamble for the transmission according to a hopping pattern associated to the RAR missing event. UE uses this method when RAR is not received. In other failure scenarios, it randomly selects preamble / RO for retransmission.

[0051] Option 2. Preamble retransmission uses different timing-offset (from second range). The preamble transmission at BS can have Guard period. The UE may send its retransmission with fixed timing offset (beyond the maximum timing offset for the cell). When BS detects the time of arrival is above offset, it can identify the retransmission.

[0052] The sequence of operations according to the first method is provided in FIG. 2. At 202, the UE 110 transmits a PRACH preamble to the gNB 170. At 204, in response to preamble misdetection by the gNB 170, either no random access response (RAR) is transmitted by the gNB 170, or the RAPID (preamble ID) included in the RAR payload by the gNB 170 is not the RAPID associated to the preamble transmission by the UE 110. The PRACH preamble transmission transmitted by the UE 110 at 202 may not be received by gNB 170, which may be the reason or cause for the preamble not being detected by the gNB 170 at 204. At 206, either the RAR is not received by the UE 110, or the RAR does not include the RAPID (preamble ID) associated to the preamble transmitted by the UE 110.

[0053] At 208, the UE 110 updates the missed RAPID rate as the number of preamble transmissions failed due to not having received RAR for the preamble (RAPID). At 210, the UE 110 performs a PRACH preamble retransmission, and action / monitoring is performed by the gNB 170 and UE 110, per operations 202, 204, 206, and 208, until a RAR including the RAPID associated to the preamble transmitted by the UE 110 is received by the UE 110. At 212, the gNB 170 transmits a next successful RAR to the UE 110. At 214, next steps of the RACH procedure are performed until there is a successful outcome.

[0054] At 216, the UE 110 transmits to the gNB 170 a UEInformationResponse message that includes one or more of (as indicated at 218): i) a number of retransmissions due to missedRAPID at the UE 110 (number of retransmissions due to non-reception of RAR or reception of RAR not carrying the RAPID corresponding to the PRACH preamble transmitted by the UE 110), ii) initial PRACH TX power applied for the first RACH attempt, iii) the list of RSRP and RSRQ measured by the UE 110 before the failed PRACH transmissions, iv) RSRP and RSRQ measured by the UE 110 before the first failed PRACH transmission, v) RSRP and RSRQ measured by the UE 110 before the last failed PRACH transmission, vi) average RSRP and RSRQ measured by the UE 110 before all the failed PRACH transmissions in this RACH attempt.

[0055] At 220, the gNB 170 can optimize the mean absolute deviation (MAD) algorithm to increase the success rate (SR) metric. At 222, the gNB 170 can adjust the PRACH receiver parameter tuning algorithm (e.g. based on the UEInformationResponse message received at 216).

[0056] The sequence of operations according to the second method is provided in FIG. 3. At 302, the UE 110 transmits a PRACH preamble to the gNB 170. At 304, in response to preamble misdetection by the gNB 170, either no random access response (RAR) is transmitted by the gNB 170, or the RAPID (preamble ID) included in the RAR payload by the gNB 170 is not the RAPID associated to the preamble transmission by the UE 110. The PRACH preamble transmission transmitted by the UE 110 at 302 may not be received by gNB 170, which may be the reason or cause for the preamble not being detected by the gNB 170 at 304. At 306, either the RAR is not received by the UE 110, or the RAR does not include the RAPID (preamble ID) associated to the preamble transmitted by the UE 110.

[0057] At 308, the UE 110 updates the missed RAPID rate as the number of preamble transmissions failed due to not having received RAR for the preamble (RAPID). At 310, the UE 110 performs a PRACH preamble retransmission, and action / monitoring is performed by the gNB 170 and UE 110, per operations 302, 304, 306, and 308, until a RAR including the RAPID associated to the preamble transmitted by the UE 110 is received by the UE 110. At 312, the gNB 170 transmits a next successful RAR to the UE 110.

[0058] At 314, the UE 110 transmits a Msg3 to the gNB 170, where the MAC control element of the Msg3 payload includes at least one or more of (as indicated at 316): i) a number of retransmissions due to missed RAPID at the UE 110 (number of retransmissions due to non-reception of RAR or reception of RAR not carrying the RAPID corresponding to thePRACH preamble transmitted by the UE 110), ii) initial PRACH TX power applied for the first RACH attempt, iii) the list of RSRP and RSRQ measured by the UE 110 before the failed PRACH transmissions, iv) RSRP and RSRQ measured by the UE 110 before the first failed PRACH transmission, v) RSRP and RSRQ measured by the UE 110 before the last failed PRACH transmission, vi) average RSRP and RSRQ measured by the UE 110 before all the failed PRACH transmissions in this RACH attempt.

[0059] At 318, the gNB 170 can optimize the mean absolute deviation (MAD) algorithm to increase the success rate (SR) metric. At 320, the gNB 170 can adjust the PRACH receiver parameter tuning algorithm (e.g. based on the Msg3 received at 314).

[0060] Concerning the 3rdmethod, and as stated above, its rationale is based on adapting the way the PRACH preamble, also known as Msgl, is transmitted. For the sake of clarity, the sequence of operations according to the 2ndoption of the third method is shown in FIG. 4 (the 1stoption can be derived straightforwardly).

[0061] Referring to FIG. 4, at 402, the UE 110 transmits a PRACH preamble to the gNB 170. At 404, in response to preamble misdetection by the gNB 170, either no random access response (RAR) is transmitted by the gNB 170, or the RAPID (preamble ID) included in the RAR payload by the gNB 170 is not the RAPID associated to the preamble transmission by the UE 110. The PRACH preamble transmission transmitted by the UE 110 at 402 may not be received by gNB 170, which may be the reason or cause for the preamble not being detected by the gNB 170 at 404. At 406, either the RAR is not received by the UE 110, or the RAR does not include the RAPID (preamble ID) associated to the preamble transmitted by the UE 110.

[0062] At 408, the UE 110 updates the missed RAPID rate as the number of preamble transmissions failed due to not having received RAR for the preamble (RAPID). At 410, the UE 110 performs optimized PRACH preamble retransmission, where the preamble is transmitted with a fixed time offset, for example, beyond the maximum timing offset for the cell.

[0063] At 412, the gNB 170 detects that the preamble time of arrival is above the expected offset, for example, the preamble time of arrival is beyond the maximum timing offset for the cell, and identifies that this is the result of a preamble retransmission and can optimize the mean absolute deviation (MAD) algorithm to increase a success rate (SR) metric. At 414, thegNB 170 adjust the PRACH receiver parameter tuning algorithm. At 416, the next steps of the RACH procedure are performed by the UE 110 and gNB 170 until the RACH procedure yields a successful outcome. The successful outcome is for example the RAR being received by the UE 110, or the RAR received by the UE 110 including the RAPID (preamble ID) being associated to the preamble transmitted by the UE 110 (or the RAPID transmitted by the UE matching the RAPID transmitted in the RAR).

[0064] The examples described herein may form a technology component within the first release of 6G.

[0065] FIG. 5 is an example apparatus 500, which may be implemented in hardware, configured to implement the examples described herein. The apparatus 500 comprises at least one processor 502 (e.g. an FPGA and / or CPU), one or more memories 504 including computer program code 505, the computer program code 505 having instructions to carry out the methods described herein, wherein the at least one memory 504 and the computer program code 505 are configured to, with the at least one processor 502, cause the apparatus 500 to implement circuitry, a process, component, module, or function (implemented with control module 506) to implement the examples described herein. The one or more memories 504 may include a non-transitory memory, a transitory memory, a volatile memory (e.g. RAM), or a non-volatile memory (e.g. ROM).

[0066] Optionally included preamble transmission 530 may implement transmission of a PRACH preamble as described herein, optionally included preamble detection 540 may implement preamble detection as described herein, and optionally included receiver optimization 550 may implement the examples described herein related to receiver optimization.

[0067] The apparatus 500 includes a display and / or RO interface 508, which includes user interface (UI) circuitry and elements, that may be used to display aspects or a status of the methods described herein (e.g., as one of the methods is being performed or at a subsequent time), or to receive input from a user such as with using a keypad, camera, touchscreen, touch area, microphone, biometric recognition, one or more sensors, etc. The apparatus 500 includes one or more communication e.g. network (N / W) interfaces (I / F(s)) 510. The communication I / F(s) 510 may be wired and / or wireless and communicate over the Internet / other network(s) via any communication technique including via one or more links524. The link(s) 524 may be the link(s) 131 and / or 176 from FIG. 1. The link(s) 131 and / or 176 from FIG. 1 may also be implemented using transceiver(s) 516 and corresponding wireless link(s) 526. The communication I / F(s) 510 may comprise one or more transmitters or one or more receivers.

[0068] The transceiver 516 comprises one or more transmitters 518 and one or more receivers 520. The transceiver 516 and / or communication FF(s) 510 may comprise standard well-known components such as an amplifier, filter, frequency-converter, (de)modulator, and encoder / decoder circuitries and one or more antennas, such as antennas 514 used for communication over wireless link 526.

[0069] The control module 506 of the apparatus 500 comprises one of or both parts 506-1 and / or 506-2, which may be implemented in a number of ways. The control module 506 may be implemented in hardware as control module 506-1, such as being implemented as part of the one or more processors 502. The control module 506-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module 506 may be implemented as control module 506-2, which is implemented as computer program code (having corresponding instructions) 505 and is executed by the one or more processors 502. For instance, the one or more memories 504 store instructions that, when executed by the one or more processors 502, cause the apparatus 500 to perform one or more of the operations as described herein. Furthermore, the one or more processors 502, the one or more memories 504, and example algorithms (e.g., as flowcharts and / or signaling diagrams), encoded as instructions, programs, or code, are means for causing performance of the operations described herein.

[0070] The apparatus 500 to implement the functionality of control 506 may be UE 110, RAN node 170 (e.g. gNB), or network element(s) 190 (e.g. LMF 190). Thus, processor 502 may correspond to processor(s) 120, processor(s) 152 and / or processor(s) 175, memory 504 may correspond to one or more memories 125, one or more memories 155 and / or one or more memories 171, computer program code 505 may correspond to computer program code 123, computer program code 153, and / or computer program code 173, control module 506 may correspond to module 140-1, module 140-2, module 150-1, and / or module 150-2, and communication I / F(s) 510 and / or transceiver 516 may correspond to transceiver 130, antenna(s) 128, transceiver 160, antenna(s) 158, N / W I / F(s) 161, and / or N / W I / F(s) 180. Alternatively, apparatus 500 and its elements may not correspond to either of UE 110, RANnode 170, or network element(s) 190 and their respective elements, as apparatus 500 may be part of a self-organizing / optimizing network (SON) node or other node, such as a node in a cloud.

[0071] The apparatus 500 may also be distributed throughout the network (e.g. 100) including within and between apparatus 500 and any network element (such as a network control element (NCE) 190 and / or the RAN node 170 and / or UE 110).

[0072] Interface 512 enables data communication and signaling between the various items of apparatus 500, as shown in FIG. 5. For example, the interface 512 may be one or more buses such as address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. Computer program code (e.g. instructions) 505, including control 506 may comprise object-oriented software configured to pass data or messages between objects within computer program code 505, or computer program code (e.g. instructions) 505, including control 506 may include functional, scripting, or procedural code. The apparatus 500 need not comprise each of the features mentioned, or may comprise other features as well. The various components of apparatus 500 may at least partially reside in a common housing 528, or a subset of the various components of apparatus 500 may at least partially be located in different housings, which different housings may include housing 528.

[0073] FIG. 6 shows a schematic representation of non-volatile memory media 600a (e.g. computer / compact disc (CD) or digital versatile disc (DVD)) and 600b (e.g. universal serial bus (USB) memory stick) and 600c (e.g. cloud storage for downloading instructions and / or parameters 602 or receiving emailed instructions and / or parameters 602) storing instructions and / or parameters 602 which when executed by a processor allows the processor to perform one or more of the steps of the methods described herein. Instructions and / or parameters 602 may represent a non-transitory computer readable medium.

[0074] FIG. 7 is an example method 700 based on the examples described herein. At 710, the method includes determining at least one metric related to a first message of a random access procedure. At 720, the method includes transmitting, to a network entity, the first message of the random access procedure. At 730, the method includes determining that a complying second message of the random access procedure was not received from thenetwork entity. At 740, the method includes transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity. At 750, the method includes wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure. Method 700 may be performed with UE 110 or apparatus 500.

[0075] FIG. 8 is an example method 800 based on the examples described herein. At 810, the method includes receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment. At 820, the method includes wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure. Method 800 may be performed with RAN node 170 or apparatus 500.

[0076] FIG. 9 is an example method 900 based on the examples described herein. At 910, the method includes transmitting a first message of a random access procedure to a network entity. At 920, the method includes in response to an event of not receiving an complying second message of the random access procedure from the network entity, transmitting, to the network entity, an enhanced first message of the random access procedure that informs the network entity that the at least one complying second message of the random access procedure was not received with an apparatus. Method 900 may be performed with UE 110 or apparatus 500.

[0077] FIG. 10 is an example method 1000 based on the examples described herein. At 1010, the method includes in response to an event of not detecting a preamble of a first message of a random access procedure or not transmitting a complying second message of the random access procedure to a user equipment, receiving, from the user equipment, an enhanced first message of the random access procedure that informs an apparatus that the preamble of the first message was not detected with the apparatus or that the apparatus did not transmit the complying second message of the random access procedure to the user equipment. At 1020, the method includes determining that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the enhanced first message of the random accessprocedure. Method 1000 may be performed with RAN node 170 or apparatus 500.

[0078] The following examples are provided and described herein.

[0079] Example 1. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine at least one metric related to a first message of a random access procedure; transmit, to a network entity, the first message of the random access procedure; determine that a complying second message of the random access procedure was not received from the network entity; and transmit, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

[0080] Example 2. The apparatus of example 1 , wherein not receiving the complying second message of the random access procedure from the network entity is based on: not receiving a random access response to the first message of the random access procedure from the network entity, or receiving, from the network entity, a random access response to the first message of the random access procedure with a preamble having a second random access preamble identifier that does not match a first random access preamble identifier of a preamble transmitted with the first message of the random access procedure, or the apparatus not receiving a random access response to the first message of the random access procedure from the network entity within a time period after transmitting the first message of the random access procedure, or the network entity not transmitting a random access response to the first message of the random access procedure to the apparatus within a time period after receiving the first message of the random access procedure, or the network entity not detecting or receiving the first message.

[0081] Example 3. The apparatus of any of examples 1 to 2, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity, an indication to provide the information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity is transmitted to the network entity in response toreceiving, from the network entity, the indication to provide the information related to not receiving the complying second message of the random access procedure from the network entity.

[0082] Example 4. The apparatus of any of examples 1 to 3, wherein the information related to not receiving the complying second message of the random access procedure from the network entity is transmitted to the network entity within a medium access control control element of the payload of a third message of the random access procedure or within a UEInformationResponse message after successful completion of the random access procedure.

[0083] Example 5. The apparatus of example 4, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity, an indication to include the information related to not receiving the complying second message of the random access procedure from the network entity within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformationResponse message after successful completion of the random access procedure; wherein the indication to include the information related to not receiving the complying second message of the random access procedure from the network entity within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformation Response message after successful completion of the random access procedure is included within a random access response to the first message of the random access procedure received from the network entity, a second message of the random access procedure received from the network entity, or an uplink grant received from the network entity.

[0084] Example 6. The apparatus of any of examples 1 to 5, wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises at least one of: a number of retransmissions of the first message of the random access procedure due to not receiving the complying second message of the random access procedure from the network entity, or a transmission power applied to the transmission of the first message of the random access procedure.

[0085] Example 7. The apparatus of example 6, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to receive from the network entity anindication to include within the information related to not receiving the complying second message of the random access procedure from the network entity at least one of: the number of retransmissions of the first message of the random access procedure due to not receiving the complying second message of the random access procedure from the network entity, or the transmission power applied to the transmission of the first message of the random access procedure.

[0086] Example 8. The apparatus of any of examples 1 to 7, wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises at least one of: a list of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or a reference signal received power measurement and a reference signal received quality measurement measured with the apparatus before a first failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or a reference signal received power measurement and a reference signal received quality measurement measured with the apparatus before a last failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or an average of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before all failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity.

[0087] Example 9. The apparatus of example 8, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to receive from the network entity an indication to include at least one of the following within the information related to not receiving the complying second message of the random access procedure from the network entity: the list of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the reference signal receivedpower measurement and the reference signal received quality measurement measured with the apparatus before the first failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the reference signal received power measurement and the reference signal received quality measurement measured with the apparatus before the last failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the average of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before all failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity.

[0088] Example 10. The apparatus of any of examples 1 to 9, wherein the information related to not receiving the complying second message of the random access procedure from the network entity is configured to be used with the network entity to adjust at least one parameter of a mean absolute deviation algorithm.

[0089] Example 11. The apparatus of any of examples 1 to 10, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: accumulate a number of failed first message transmissions of the random access procedure based on the complying second message not being received.

[0090] Example 12. An apparatus of any of examples 1 to 11, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: in response to not having received the at least one complying second message of the random access procedure from the network entity after the transmission of the first message of the random access procedure to the network entity: transmitting one or more information elements in a radio resource control message to the network entity, wherein additional fields for requesting the one or more information elements are included into another radio resource control message received with the user equipment from the network entity; wherein the one or more information elements in the radio resource control message transmitted to the network entity comprises the information related to not receiving the complying second message of the random access procedure from the network entity.

[0091] Example 13. An apparatus including: at least one processor; and at least one memorystoring instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a user equipment, information related to the apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

[0092] Example 14. The apparatus of example 13, wherein the apparatus not transmitting the complying second message of the random access procedure is based on: not transmitting a random access response to the first message of the random access procedure to the user equipment, or transmitting, to the user equipment, a random access response to the first message of the random access procedure with a preamble having a second random access preamble identifier that does not match a first random access preamble identifier of a preamble of the first message of the random access procedure, or the user equipment not receiving a random access response to the first message of the random access procedure from the apparatus within a time period after transmission of the first message of the random access procedure, or the apparatus not transmitting a random access response to the first message of the random access procedure to the user equipment within a time period after receiving the first message of the random access procedure from the user equipment, or the apparatus not detecting or receiving the first message.

[0093] Example 15. The apparatus of any of examples 13 to 14, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to provide the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment is received from the user equipment in response to transmitting, to the user equipment, the indication to provide the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

[0094] Example 16. The apparatus of any of examples 13 to 15, wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment is received from the user equipment within a medium access control control element of a payload of a third message of the random access procedure orwithin a UEInformationResponse message after successful completion of the random access procedure.

[0095] Example 17. The apparatus of example 16, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to include the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformationResponse message after successful completion of the random access procedure; wherein the indication to include the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformation Response message after successful completion of the random access procedure is included within a random access response to the first message of the random access procedure transmitted to the user equipment, a second message of the random access procedure transmitted to the user equipment, or an uplink grant transmitted to the user equipment.

[0096] Example 18. The apparatus of any of examples 13 to 17, wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one of: a number of retransmissions of the first message of the random access procedure due to the apparatus not transmitting the complying second message of the random access procedure to the user equipment, or a transmission power applied to a transmission of the first message of the random access procedure.

[0097] Example 19. The apparatus of example 18, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to transmit to the user equipment an indication to include within the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment at least one of: the number of retransmissions of the first message of the random access procedure due to the apparatus not transmitting the complying second message of the random access procedure to the user equipment, or the transmission power applied to the transmission of the first message of the random access procedure.

[0098] Example 20. The apparatus of any of examples 13 to 19, wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one of: a list of reference signal received power measurements and reference signal received quality measurements measured before failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or a reference signal received power measurement and a reference signal received quality measurement measured before a first failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or a reference signal received power measurement and a reference signal received quality measurement measured before a last failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or an average of reference signal received power measurements and reference signal received quality measurements measured before all failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment.

[0099] Example 21. The apparatus of example 20, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to transmit to the user equipment an indication to include at least one of the following within the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment: the list of reference signal received power measurements and reference signal received quality measurements measured before failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the reference signal received power measurement and the reference signal received quality measurement measured before the first failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the reference signal received power measurement and the reference signal received quality measurement measured before the last failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the average of reference signal received power measurements and referencesignal received quality measurements measured before all failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment.

[0100] Example 22. The apparatus of any of examples 13 to 21, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: adjust at least one parameter of a mean absolute deviation algorithm, based on the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

[0101] Example 23. The apparatus of any of examples 13 to 22, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to accumulate a number of failed transmissions of the first message of the random access procedure based on the apparatus not detecting a preamble of the first message or the apparatus not transmitting the complying second message to the user equipment.

[0102] Example 24. The apparatus of any of examples 13 to 23, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: in response to not having transmitted the complying second message of the random access procedure to the user equipment: receiving one or more information elements in a radio resource control message from the user equipment, wherein additional fields for requesting the one or more information elements are included into another radio resource control message transmitted from the apparatus to the user equipment; wherein the one or more information elements in the radio resource control message received from the user equipment comprises the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

[0103] Example 25. A method including: determining at least one metric related to a first message of a random access procedure; transmitting, to a network entity, the first message of the random access procedure; determining that a complying second message of the random access procedure was not received from the network entity; and transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entitycomprises the at least one metric related to the first message of the random access procedure.

[0104] Example 26. A method including: receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

[0105] Example 27. An apparatus including: means for determining at least one metric related to a first message of a random access procedure; means for transmitting, to a network entity, the first message of the random access procedure; means for determining that a complying second message of the random access procedure was not received from the network entity; and means for transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

[0106] Example 28. An apparatus including: means for receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

[0107] Example 29. A computer readable medium including instructions stored thereon for performing at least the following: determining at least one metric related to a first message of a random access procedure; transmitting, to a network entity, the first message of the random access procedure; determining that a complying second message of the random access procedure was not received from the network entity; and transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

[0108] Example 30. A computer readable medium including instructions stored thereon for performing at least the following: receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

[0109] Example 31. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: transmit a first message of a random access procedure to a network entity; and in response to an event of not receiving an complying second message of the random access procedure from the network entity, transmit, to the network entity, an enhanced first message of the random access procedure that informs the network entity that the at least one complying second message of the random access procedure was not received with the apparatus.

[0110] Example 32. The apparatus of example 31, wherein transmitting the enhanced first message of the random access procedure to the network entity comprises choosing a random access occasion for transmitting the enhanced first message based on a sequence of random access occasions associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure.

[0111] Example 33. The apparatus of example 32, wherein the sequence of random access occasions comprises a hopping pattern.

[0112] Example 34. The apparatus of any of examples 32 to 33, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: determine the sequence of random access occasions associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure based on a specification.

[0113] Example 35. The apparatus of any of examples 32 to 34, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity via higher layer signaling, a configuration; and determine the sequence of random access occasions associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message ofthe random access procedure based on the configuration received from the network entity via higher layer signaling.

[0114] Example 36. The apparatus of any of examples 31 to 35, wherein transmitting the enhanced first message of the random access procedure to the network entity comprises choosing a preamble for transmitting the enhanced first message based on a sequence of preambles associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure, and wherein the preamble is part of the sequence and different from a preamble chosen with the apparatus for the transmission of the first message of the random access procedure.

[0115] Example 37. The apparatus of example 36, wherein the sequence of preambles comprises a hopping pattern.

[0116] Example 38. The apparatus of any of examples 36 to 37, wherein the preamble is chosen based on a specification or based on higher layer signaling received from the network entity.

[0117] Example 39. The apparatus of any of examples 31 to 38, wherein transmitting the enhanced first message of the random access procedure to the network entity comprises performing transmission of a preamble for the enhanced first message using a timing offset associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure, wherein the timing offset is different from a timing offset used for the transmission of the first message of the random access procedure.

[0118] Example 40. The apparatus of example 39, wherein the timing offset associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure is chosen from a second range of timing offsets different from a first range of timing offsets used for the transmission of the first message of the random access procedure.

[0119] Example 41. The apparatus of any of examples 39 to 40, wherein the timing offset associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure isfixed and larger than a maximum timing offset for a cell accessed with the apparatus.

[0120] Example 42. The apparatus of examples 39 or 40, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: determine the timing offset or the second range of timing offsets associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the same random access procedure based on a specification.

[0121] Example 43. The apparatus of examples 39 or 40, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity via higher layer signaling, a configuration; and determine the timing offset or the second range of timing offsets associated to the event of not receiving the complying second message of the random access procedure following the transmission of the first message of the random access procedure based on the configuration received from the network entity via higher layer signaling.

[0122] Example 44. The apparatus of example 43, wherein the network entity attempts to detect the first message within the first range of timing offsets and the second range of timing offsets, when the apparatus configures the user equipment with the second range of timing offsets for the enhanced first message.

[0123] Example 45. The apparatus of examples 39 or 40, wherein a time of arrival of the enhanced first message being above an expected offset informs the network entity that the complying second message of the random access procedure was not received with the apparatus.

[0124] Example 46. The apparatus of any of examples 31 to 45, wherein the first message comprises a transmission on a physical random access channel, and the enhanced first message comprises: a retransmission on the physical random access channel, or a retransmission on the physical random access channel of multiple retransmissions on the physical random access channel.

[0125] Example 47. The apparatus of any of examples 31 to 46, wherein not receiving the complying second message of the random access procedure from the network entity is based on: not receiving a random access response to the first message of the random access procedure from the network entity, or receiving, from the network entity, a random accessresponse to the first message of the random access procedure with a second random access preamble identifier that does not match a first random access preamble identifier transmitted with the first message of the random access procedure, or the apparatus not receiving a random access response to the first message of the random access procedure within a time period after transmitting the first message of the random access procedure, or the network entity not transmitting a random access response to the first message of the random access procedure within a time period after receiving the first message of the random access procedure, or the network entity not detecting or receiving the first message.

[0126] Example 48. The apparatus of any of examples 31 to 47, wherein the enhanced first message of the random access procedure is configured to be used with the network entity to adjust a parameter of a physical random access channel receiver of the network entity.

[0127] Example 49. The apparatus of any of examples 31 to 48, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: determine a physical random access channel preamble for the first message of the random access procedure based on random selection, or determine a configuration for the first message based on a random process; and determine a physical random access channel preamble for the enhanced first message of the random access procedure based on deterministic selection, or determine a configuration for the enhanced first message based on a deterministic process.

[0128] Example 50. The apparatus of any of examples 31 to 49, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit multiple enhanced first messages of the random access procedure that informs the network entity that for multiple successive failed attempts to transmit the first message of the random access procedure, that the at least one complying second message of the random access procedure was not received with the apparatus; and receive an indication that for the multiple successive failed attempts, the at least one complying second message of the random access procedure was not received with the apparatus.

[0129] Example 51. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: in response to an event of not detecting a preamble of a first message of a random access procedure or not transmitting a complying second message of the random access procedure to a user equipment, receive, from the user equipment, an enhanced first messageof the random access procedure that informs the apparatus that the preamble of the first message was not detected with the apparatus or that the apparatus did not transmit the complying second message of the random access procedure to the user equipment; and determine that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the enhanced first message of the random access procedure.

[0130] Example 52. The apparatus of example 51, wherein the enhanced first message of the random access procedure is based on a random access occasion for the enhanced first message, wherein the random access occasion is based on a sequence of random access occasions associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure.

[0131] Example 53. The apparatus of example 52, wherein the sequence of random access occasions comprises a hopping pattern.

[0132] Example 54. The apparatus of any of examples 52 to 53, wherein the sequence of random access occasions associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is based on a specification.

[0133] Example 55. The apparatus of any of examples 52 to 54, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment via higher layer signaling, a configuration; wherein the sequence of random access occasions associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is based on the configuration transmitted to the user equipment via higher layer signaling.

[0134] Example 56. The apparatus of any of examples 51 to 55, wherein the enhanced first message of the random access procedure is received from the user equipment with a preamble based on a sequence of preambles associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure, and wherein the preamble is part of the sequenceand different from a preamble used for the first message of the random access procedure.

[0135] Example 57. The apparatus of example 56, wherein the sequence of preambles comprises a hopping pattern.

[0136] Example 58. The apparatus of any of examples 56 to 57, wherein the preamble is determined based on a specification or based on higher layer signaling transmitted from the apparatus to the user equipment.

[0137] Example 59. The apparatus of any of examples 51 to 58, wherein the enhanced first message of the random access procedure is received with a preamble using a timing offset associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure, wherein the timing offset is different from a timing offset used for the first message of the random access procedure.

[0138] Example 60. The apparatus of example 59, wherein the timing offset associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is from a second range of timing offsets different from a first range of timing offsets used for the first message of the random access procedure.

[0139] Example 61. The apparatus of any of examples 59 to 60, wherein the timing offset associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is fixed and larger than a maximum timing offset for a cell to which the apparatus provides access.

[0140] Example 62. The apparatus of examples 59 or 60, wherein the timing offset or the second range of timing offsets associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is based on a specification.

[0141] Example 63. The apparatus of examples 59 or 60, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment via higher layer signaling, a configuration; wherein the timing offset or the secondrange of timing offsets associated to the event of not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure is based on the configuration transmitted to the user equipment via higher layer signaling.

[0142] Example 64. The apparatus of example 63, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: determine to attempt to detect the first message within the first range of timing offsets and the second range of timing offsets, when the apparatus configures the user equipment with the second range of timing offsets for the enhanced first message.

[0143] Example 65. The apparatus of examples 59 or 60, wherein a time of arrival of the enhanced first message being above an expected offset informs the apparatus that the apparatus did not detect the preamble of the first message of the random access procedure or that the apparatus did not transmit the complying second message of the random access procedure.

[0144] Example 66. The apparatus of any of examples 51 to 65, wherein the first message of the random access procedure comprises a transmission on a physical random access channel, and the enhanced first message comprises: a retransmission on the physical random access channel, or a retransmission on the physical random access channel of multiple retransmissions on the physical random access channel.

[0145] Example 67. The apparatus of any of examples 51 to 66, wherein not detecting the preamble of the first message of the random access procedure or not transmitting the complying second message of the random access procedure to the user equipment is based on: not transmitting a random access response to the first message of the random access procedure to the user equipment, or transmitting, to the user equipment, a random access response to the first message of the random access procedure with a second random access preamble identifier that does not match a first random access preamble identifier used with the first message of the random access procedure, or the user equipment not receiving a random access response to the first message of the random access procedure within a time period after transmission of the first message of the random access procedure, or the apparatus not transmitting a random access response to the first message of the random access procedure within a time period after receiving the first message of the random access procedure, or theapparatus not detecting or receiving the first message.

[0146] Example 68. The apparatus of any of examples 51 to 67, wherein the instructions, when executed by the at least one processor, causes the apparatus at least to: adjust a parameter of a physical random access channel receiver of the apparatus, based on the enhanced first message of the random access procedure received from the user equipment.

[0147] Example 69. The apparatus of any of examples 51 to 68, wherein: the preamble for the first message of the random access procedure is based on random selection, a configuration for the first message is based on a random process; and a preamble for the enhanced first message of the random access procedure is based on deterministic selection, or a configuration for the enhanced first message is based on a deterministic process.

[0148] Example 70. The apparatus of any of examples 51 to 69, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive multiple enhanced first messages of the random access procedure that informs the apparatus that for multiple successive failed attempts to transmit the first message of the random access procedure, the preamble of the first message was not detected with the apparatus or the apparatus did not transmit the complying second message of the random access procedure to the user equipment; determine, for the multiple successive failed attempts, that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the multiple enhanced first messages of the random access procedure; and transmit an indication that for the multiple successive failed attempts, the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure.

[0149] Example 71. A method including: transmitting a first message of a random access procedure to a network entity; and in response to an event of not receiving an complying second message of the random access procedure from the network entity, transmitting, to the network entity, an enhanced first message of the random access procedure that informs the network entity that the at least one complying second message of the random access procedure was not received with an apparatus.

[0150] Example 72. A method including: in response to an event of not detecting a preambleof a first message of a random access procedure or not transmitting a complying second message of the random access procedure to a user equipment, receiving, from the user equipment, an enhanced first message of the random access procedure that informs an apparatus that the preamble of the first message was not detected with the apparatus or that the apparatus did not transmit the complying second message of the random access procedure to the user equipment; and determining that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the enhanced first message of the random access procedure.

[0151] Example 73. An apparatus including: means for transmitting a first message of a random access procedure to a network entity; and means for, in response to an event of not receiving an complying second message of the random access procedure from the network entity, transmitting, to the network entity, an enhanced first message of the random access procedure that informs the network entity that the at least one complying second message of the random access procedure was not received with the apparatus.

[0152] Example 74. An apparatus including: means for, in response to an event of not detecting a preamble of a first message of a random access procedure or not transmitting a complying second message of the random access procedure to a user equipment, receiving, from the user equipment, an enhanced first message of the random access procedure that informs the apparatus that the preamble of the first message was not detected with the apparatus or that the apparatus did not transmit the complying second message of the random access procedure to the user equipment; and means for determining that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the enhanced first message of the random access procedure.

[0153] Example 75. A computer readable medium including instructions stored thereon for performing at least the following: transmitting a first message of a random access procedure to a network entity; and in response to an event of not receiving an complying second message of the random access procedure from the network entity, transmitting, to the network entity, an enhanced first message of the random access procedure that informs the network entity that the at least one complying second message of the random access procedure was notreceived with an apparatus.

[0154] Example 76. A computer readable medium including instructions stored thereon for performing at least the following: in response to an event of not detecting a preamble of a first message of a random access procedure or not transmitting a complying second message of the random access procedure to a user equipment, receiving, from the user equipment, an enhanced first message of the random access procedure that informs an apparatus that the preamble of the first message was not detected with the apparatus or that the apparatus did not transmit the complying second message of the random access procedure to the user equipment; and determining that the preamble of the first message of the random access procedure was not detected with the apparatus, or that the apparatus did not transmit the complying second message of the random access procedure, based on receiving, from the user equipment, the enhanced first message of the random access procedure.

[0155] References to a ‘computer’, ‘processor’, etc. should be understood to encompass not only computers having different architectures such as single / multi-processor architectures and sequential or parallel architectures but also specialized circuits such as field- programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

[0156] The memories as described herein may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transitory memory, fixed memory and removable memory. The memories may comprise a database for storing data.

[0157] As used herein, the term ‘circuitry’ may refer to the following: (a) hardware circuit implementations, such as implementations in analog and / or digital circuitry, and (b) combinations of circuits and software (and / or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s) / software including digital signal processor(s), software, and memories that work together to cause an apparatus to performvarious functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. As a further example, as used herein, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

[0158] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications may be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different example embodiments described above could be selectively combined into a new example embodiment. Accordingly, this description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

[0159] The following acronyms and abbreviations that may be found in the specification and / or the drawing figures are given as follows (the abbreviations and acronyms may be appended / combined with each other or with other characters using e.g. a dash, hyphen, slash, letter, or number, and may be case insensitive):3GPP third generation partnership project4G fourth generation5G fifth generation5GC 5G core network6G sixth generationAMF access and mobility management functionASIC application- specific integrated circuitBS base stationBWP bandwidth partCD compact / computer discCPU central processing unitCRC cyclic redundancy checkCU central unit or centralized unitDCI downlink control informationDSP digital signal processorDU distributed unitDVD digital versatile disc eNB evolved Node B (e.g., an LTE base station)EN-DC E-UTRAN new radio - dual connectivity en-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as a secondary node in EN- DCE-UTRA evolved UMTS terrestrial radio access, i.e., the LTE radio access technologyE-UTRAN E-UTRA networkFl interface between the CU and the DUFPGA field-programmable gate array gNB generalized node B, base station for 5G / NR, i.e., a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GCGP guard periodHW hardwareIAB integrated access and backhaulID identifierPF interfaceRO input / outputKPI key performance indicatorLMF location management functionLTE long term evolution (4G)MAC medium access controlMAD mean absolute deviationMME mobility management entityMRO mobility robustness optimizationMsgl message 1 of a random access procedure (e.g. a four step RACH procedure)Msg2 message 2 of a random access procedure (e.g. a four step RACH procedure)Msg3 message 3 of a random access procedure (e.g. a four step RACH procedure)NCE network control element ng or NG new generation ng-eNB new generation eNB NG-RAN new generation radio access network NR new radio N / W network PDA personal digital assistant PDCCH physical downlink control channel PDCP packet data convergence protocol PDSCH physical downlink shared channel PHY physical layer PRACH physical random access channel PUSCH physical uplink shared channel RACH random access channel RAM random access memory RAN radio access network RAPID random access preamble ID RAR random access response RA-RNTI random access radio network temporary identifier RLC radio link control RO RACH occasion ROM read-only memory RRC radio resource control RSRP reference signal received power RSRQ reference signal received quality RU radio unit Rx receive, or receiver, or reception SDAP service data adaptation protocol SGW serving gateway SIB system information block (e.g. SIB1) SMF session management function SON self-organizing / optimizing networkSR success rateSW softwareT1 upper or lower bound thresholdTN upper or lower bound thresholdTRP transmission reception pointTx transmit, or transmitter, or transmissionUAV unmanned aerial vehicleUE user equipment (e.g., a wireless, typically mobile device)UI user interfaceUL uplinkUMTS Universal Mobile Telecommunications SystemUPF user plane functionUSB universal serial busX2 network interface between RAN nodes and between RAN and the core networkXn network interface between NG-RAN nodes

Claims

CLAIMSWhat is claimed is:

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: determine at least one metric related to a first message of a random access procedure; transmit, to a network entity, the first message of the random access procedure; determine that a complying second message of the random access procedure was not received from the network entity; and transmit, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

2. The apparatus of claim 1, wherein not receiving the complying second message of the random access procedure from the network entity is based on: not receiving a random access response to the first message of the random access procedure from the network entity, or receiving, from the network entity, a random access response to the first message of the random access procedure with a preamble having a second random access preamble identifier that does not match a first random access preamble identifier of a preamble transmitted with the first message of the random access procedure, or the apparatus not receiving a random access response to the first message of therandom access procedure from the network entity within a time period after transmitting the first message of the random access procedure, or the network entity not transmitting a random access response to the first message of the random access procedure to the apparatus within a time period after receiving the first message of the random access procedure, or the network entity not detecting or receiving the first message.

3. The apparatus of any of claims 1 to 2, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity, an indication to provide the information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity is transmitted to the network entity in response to receiving, from the network entity, the indication to provide the information related to not receiving the complying second message of the random access procedure from the network entity.

4. The apparatus of any of claims 1 to 3, wherein the information related to not receiving the complying second message of the random access procedure from the network entity is transmitted to the network entity within a medium access control control element of the payload of a third message of the random access procedure or within a UEInformationResponse message after successful completion of the random access procedure.

5. The apparatus of claim 4, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: receive, from the network entity, an indication to include the information related to not receiving the complying second message of the random access procedure from the network entity within the medium access control control element of the payload of the third message of the random access procedure or within theUEInformationResponse message after successful completion of the random access procedure; wherein the indication to include the information related to not receiving the complying second message of the random access procedure from the network entity within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformation Response message after successful completion of the random access procedure is included within a random access response to the first message of the random access procedure received from the network entity, a second message of the random access procedure received from the network entity, or an uplink grant received from the network entity.

6. The apparatus of any of claims 1 to 5, wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises at least one of: a number of retransmissions of the first message of the random access procedure due to not receiving the complying second message of the random access procedure from the network entity, or a transmission power applied to the transmission of the first message of the random access procedure.

7. The apparatus of claim 6, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to receive from the network entity an indication to include within the information related to not receiving the complying second message of the random access procedure from the network entity at least one of: the number of retransmissions of the first message of the random access procedure due to not receiving the complying second message of the random access procedure from the network entity, or the transmission power applied to the transmission of the first message of the random access procedure.

8. The apparatus of any of claims 1 to 7, wherein the information related to not receivingthe complying second message of the random access procedure from the network entity comprises at least one of: a list of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or a reference signal received power measurement and a reference signal received quality measurement measured with the apparatus before a first failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or a reference signal received power measurement and a reference signal received quality measurement measured with the apparatus before a last failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or an average of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before all failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity.

9. The apparatus of claim 8, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to receive from the network entity an indication to include at least one of the following within the information related to not receiving the complying second message of the random access procedure from the network entity: the list of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the reference signal received power measurement and the reference signalreceived quality measurement measured with the apparatus before the first failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the reference signal received power measurement and the reference signal received quality measurement measured with the apparatus before the last failed transmission of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity, or the average of reference signal received power measurements and reference signal received quality measurements measured with the apparatus before all failed transmissions of the first message of the random access procedure where the complying second message of the random access procedure was not received from the network entity.

10. The apparatus of any of claims 1 to 9, wherein the information related to not receiving the complying second message of the random access procedure from the network entity is configured to be used with the network entity to adjust at least one parameter of a mean absolute deviation algorithm.

11. The apparatus of any of claims 1 to 10, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: accumulate a number of failed first message transmissions of the random access procedure based on the complying second message not being received.

12. An apparatus of any of claims 1 to 11, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: in response to not having received the at least one complying second message of the random access procedure from the network entity after the transmission of the first message of the random access procedure to the network entity: transmitting one or more information elements in a radio resource control message to the network entity,wherein additional fields for requesting the one or more information elements are included into another radio resource control message received with the user equipment from the network entity; wherein the one or more information elements in the radio resource control message transmitted to the network entity comprises the information related to not receiving the complying second message of the random access procedure from the network entity.

13. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a user equipment, information related to the apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

14. The apparatus of claim 13, wherein the apparatus not transmitting the complying second message of the random access procedure is based on: not transmitting a random access response to the first message of the random access procedure to the user equipment, or transmitting, to the user equipment, a random access response to the first message of the random access procedure with a preamble having a second random access preamble identifier that does not match a first random access preamble identifier of a preamble of the first message of the random access procedure, or the user equipment not receiving a random access response to the first message of the random access procedure from the apparatus within a time period aftertransmission of the first message of the random access procedure, or the apparatus not transmitting a random access response to the first message of the random access procedure to the user equipment within a time period after receiving the first message of the random access procedure from the user equipment, or the apparatus not detecting or receiving the first message.

15. The apparatus of any of claims 13 to 14, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to provide the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment is received from the user equipment in response to transmitting, to the user equipment, the indication to provide the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

16. The apparatus of any of claims 13 to 15, wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment is received from the user equipment within a medium access control control element of a payload of a third message of the random access procedure or within a UEInformationResponse message after successful completion of the random access procedure.

17. The apparatus of claim 16, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to include the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformationResponse message after successful completion of the random accessprocedure; wherein the indication to include the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment within the medium access control control element of the payload of the third message of the random access procedure or within the UEInformation Response message after successful completion of the random access procedure is included within a random access response to the first message of the random access procedure transmitted to the user equipment, a second message of the random access procedure transmitted to the user equipment, or an uplink grant transmitted to the user equipment.

18. The apparatus of any of claims 13 to 17, wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one of: a number of retransmissions of the first message of the random access procedure due to the apparatus not transmitting the complying second message of the random access procedure to the user equipment, or a transmission power applied to a transmission of the first message of the random access procedure.

19. The apparatus of claim 18, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to transmit to the user equipment an indication to include within the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment at least one of: the number of retransmissions of the first message of the random access procedure due to the apparatus not transmitting the complying second message of the random access procedure to the user equipment, or the transmission power applied to the transmission of the first message of the random access procedure.

20. The apparatus of any of claims 13 to 19, wherein the information related to theapparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one of: a list of reference signal received power measurements and reference signal received quality measurements measured before failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or a reference signal received power measurement and a reference signal received quality measurement measured before a first failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or a reference signal received power measurement and a reference signal received quality measurement measured before a last failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or an average of reference signal received power measurements and reference signal received quality measurements measured before all failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment.

21. The apparatus of claim 20, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to transmit to the user equipment an indication to include at least one of the following within the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment: the list of reference signal received power measurements and reference signal received quality measurements measured before failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the reference signal received power measurement and the reference signalreceived quality measurement measured before the first failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the reference signal received power measurement and the reference signal received quality measurement measured before the last failed transmission of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment, or the average of reference signal received power measurements and reference signal received quality measurements measured before all failed transmissions of the first message of the random access procedure where the apparatus did not transmit the complying second message of the random access procedure to the user equipment.

22. The apparatus of any of claims 13 to 21, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: adjust at least one parameter of a mean absolute deviation algorithm, based on the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

23. The apparatus of any of claims 13 to 22, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: transmit, to the user equipment, an indication to accumulate a number of failed transmissions of the first message of the random access procedure based on the apparatus not detecting a preamble of the first message or the apparatus not transmitting the complying second message to the user equipment.

24. The apparatus of any of claims 13 to 23, wherein the instructions, when executed by the at least one processor, cause the apparatus at least to: in response to not having transmitted the complying second message of the random access procedure to the user equipment: receiving one or more information elements in a radio resource control message from the user equipment, wherein additional fields for requesting the one or more information elements are included intoanother radio resource control message transmitted from the apparatus to the user equipment; wherein the one or more information elements in the radio resource control message received from the user equipment comprises the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment.

25. A method comprising: determining at least one metric related to a first message of a random access procedure; transmitting, to a network entity, the first message of the random access procedure; determining that a complying second message of the random access procedure was not received from the network entity; and transmitting, to the network entity, information related to not receiving the complying second message of the random access procedure from the network entity; wherein the information related to not receiving the complying second message of the random access procedure from the network entity comprises the at least one metric related to the first message of the random access procedure.

26. A method comprising: receiving, from a user equipment, information related to an apparatus not transmitting a complying second message of a random access procedure to the user equipment; wherein the information related to the apparatus not transmitting the complying second message of the random access procedure to the user equipment comprises at least one metric related to a first message of the random access procedure.

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