US-12621872-B2 - Random access

US12621872B2US 12621872 B2US12621872 B2US 12621872B2US-12621872-B2

Abstract

There is provided a method, comprising: obtaining signal quality information on a plurality of downlink (DL) signals of a cell; receiving, from a network node of the cell, condition information indicative of reception conditions at the network node; based on the signal quality information and the condition information, determining at least one parameter for performing a random access to the cell; performing, based on the determined at least one parameter, the random access to the cell on a set of uplink (UL) resources.

Inventors

Alessio MARCONE
Marco MASO
Nhat-Quang Nhan
Diomidis Michalopoulos
Ali Karimidehkordi
Daniel Medina
Amir Mehdi Ahmadian Tehrani
Prajwal KESHAVAMURTHY

Assignees

NOKIA TECHNOLOGIES OY

Dates

Publication Date: 20260505
Application Date: 20231011
Priority Date: 20221115

Claims (20)

1 . An apparatus comprising: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the apparatus to operate as a 5G new radio (NR) user equipment (UE) to perform the following operations: obtain signal quality information comprising layer-1 reference signal received power (L1-RSRP) measurements for a plurality of synchronization signal blocks (SSBs) detected in a beam-sweeping burst of a cell; receive, from a gNB of the cell, system information comprising a time-varying, SSB-indexed table that (i) is broadcast in a system information block (SIB) and (ii) for each SSB includes 2-bit quantized values of: (a) interference or noise power at the gNB on uplink resources corresponding to the SSB, (b) random-access (RA) collision probability, and (c) an average observed latency from preamble transmission to RA completion, together with (iii) a per-SSB RSRP-threshold offset and (iv) threshold values and an update periodicity applicable to the quantized values; based on both the L1-RSRP measurements and the received table, determine a particular SSB index with which to associate a contention-based four-step random access (CBRA) procedure and a maximum number of physical random access channel (PRACH) repetitions, wherein the determining comprises: adjusting an RSRP threshold by the per-SSB offset and, responsive to an interference value for a highest-RSRP SSB exceeding the interference threshold, selecting instead a different SSB having next-highest RSRP whose interference value does not exceed the interference threshold; responsive to a collision-probability value for the selected SSB exceeding a collision threshold and the UE determining that RA repetition occasions are shared among UEs, reducing the maximum number of PRACH repetitions relative to a number derived from the adjusted RSRP threshold, but responsive to the collision-probability value exceeding the collision threshold and the UE determining that repetition occasions are pseudo-randomly selected, increasing the maximum number of PRACH repetitions; responsive to an average-latency value for the selected SSB exceeding a latency threshold: decreasing the maximum number of PRACH repetitions or re-selecting the SSB; and applying a priority in which interference information takes precedence over latency information when indications conflict; and perform the random access based on the determined SSB index and maximum number of PRACH repetitions by transmitting Msg1 preambles on PRACH uplink resources mapped from the determined SSB index according to an SSB-to-random-access-occasion mapping signaled in SIB1, with the number of Msg1 transmissions capped by the maximum number of PRACH repetitions and terminated early upon receipt of a random access response (Msg2).
2 . The apparatus of claim 1 , wherein the condition information is received in a system information block (SIB) broadcast by the gNB, the SIB including an SSB-indexed table having quantized values of interference, collision probability, latency, and offset, each encoded in 2 bits.
3 . The apparatus of claim 2 , wherein determining the at least one parameter comprises applying a per-SSB offset to an RSRP threshold configured by the gNB to adjust the number of PRACH repetitions.
4 . The apparatus of claim 3 , wherein the at least one parameter comprises a maximum number of PRACH repetitions, and the apparatus terminates Msg1 transmissions early when a random access response (Msg2) is received prior to completing all repetitions.
5 . The apparatus of claim 4 , wherein determining the at least one parameter further comprises reducing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and random access occasions are shared among UEs in the cell.
6 . The apparatus of claim 4 , wherein determining the at least one parameter further comprises increasing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and the random access occasions are pseudo-randomly selected among UEs in the cell.
7 . The apparatus of claim 6 , wherein the condition information includes an update periodicity, and the apparatus applies the condition information only during a validity duration indicated by the gNB.
8 . A system comprising: an apparatus: at least one processor; and at least one non-transitory memory storing instructions that, when executed by the at least one processor, cause the apparatus to operate as a 5G new radio (NR) user equipment (UE) to perform the following operations: obtain signal quality information comprising layer-1 reference signal received power (L1-RSRP) measurements for a plurality of synchronization signal blocks (SSBs) detected in a beam-sweeping burst of a cell; receive, from a gNB of the cell, system information comprising a time-varying, SSB-indexed table that (i) is broadcast in a system information block (SIB) and (ii) for each SSB includes 2-bit quantized values of: (a) interference or noise power at the gNB on uplink resources corresponding to the SSB, (b) random-access (RA) collision probability, and (c) an average observed latency from preamble transmission to RA completion, together with (iii) a per-SSB RSRP-threshold offset and (iv) threshold values and an update periodicity applicable to the quantized values; based on both the L1-RSRP measurements and the received table, determine a particular SSB index with which to associate a contention-based four-step random access (CBRA) procedure and a maximum number of physical random access channel (PRACH) repetitions, wherein the determining comprises: adjusting an RSRP threshold by the per-SSB offset and, responsive to an interference value for a highest-RSRP SSB exceeding the interference threshold, selecting instead a different SSB having next-highest RSRP whose interference value does not exceed the interference threshold; responsive to a collision-probability value for the selected SSB exceeding a collision threshold and the UE determining that RA repetition occasions are shared among UEs, reducing the maximum number of PRACH repetitions relative to a number derived from the adjusted RSRP threshold, but responsive to the collision-probability value exceeding the collision threshold and the UE determining that repetition occasions are pseudo-randomly selected, increasing the maximum number of PRACH repetitions; responsive to an average-latency value for the selected SSB exceeding a latency threshold: decreasing the maximum number of PRACH repetitions or re-selecting the SSB; and applying a priority in which interference information takes precedence over latency information when indications conflict; and perform the random access based on the determined SSB index and maximum number of PRACH repetitions by transmitting Msg1 preambles on PRACH uplink resources mapped from the determined SSB index according to an SSB-to-random-access-occasion mapping signaled in SIB1, with the number of Msg1 transmissions capped by the maximum number of PRACH repetitions and terminated early upon receipt of a random access response (Msg2).
9 . The apparatus of claim 8 , wherein the condition information is received in a system information block (SIB) broadcast by the gNB, the SIB including an SSB-indexed table having quantized values of interference, collision probability, latency, and offset, each encoded in 2 bits.
10 . The apparatus of claim 9 , wherein determining the at least one parameter comprises applying a per-SSB offset to an RSRP threshold configured by the gNB to adjust the number of PRACH repetitions.
11 . The apparatus of claim 10 , wherein the at least one parameter comprises a maximum number of PRACH repetitions, and the apparatus terminates Msg1 transmissions early when a random access response (Msg2) is received prior to completing all repetitions.
12 . The apparatus of claim 11 , wherein determining the at least one parameter further comprises reducing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and random access occasions are shared among UEs in the cell.
13 . The apparatus of claim 11 , wherein determining the at least one parameter further comprises increasing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and the random access occasions are pseudo-randomly selected among UEs in the cell.
14 . The apparatus of claim 12 , wherein the condition information includes an update periodicity, and the apparatus applies the condition information only during a validity duration indicated by the gNB.
15 . A method performed by a 5G new radio (NR) user equipment (UE), the method comprising: obtaining signal quality information comprising layer-1 reference signal received power (L1-RSRP) measurements for a plurality of synchronization signal blocks (SSBs) detected in a beam-sweeping burst of a cell; receiving, from a gNB of the cell, system information comprising a time-varying, SSB-indexed table that (i) is broadcast in a system information block (SIB) and (ii) for each SSB includes 2-bit quantized values of: (a) interference or noise power at the gNB on uplink resources corresponding to the SSB, (b) random-access (RA) collision probability, and (c) an average observed latency from preamble transmission to RA completion, together with (iii) a per-SSB RSRP-threshold offset and (iv) threshold values and an update periodicity applicable to the quantized values; based on both the L1-RSRP measurements and the received table, determining a particular SSB index with which to associate a contention-based four-step random access (CBRA) procedure and a maximum number of physical random access channel (PRACH) repetitions, wherein the determining comprises: adjusting an RSRP threshold by the per-SSB offset and, responsive to an interference value for a highest-RSRP SSB exceeding the interference threshold, selecting instead a different SSB having next-highest RSRP whose interference value does not exceed the interference threshold; responsive to a collision-probability value for the selected SSB exceeding a collision threshold and the UE determining that RA repetition occasions are shared among UEs, reducing the maximum number of PRACH repetitions relative to a number derived from the adjusted RSRP threshold, but responsive to the collision-probability value exceeding the collision threshold and the UE determining that repetition occasions are pseudo-randomly selected, increasing the maximum number of PRACH repetitions; responsive to an average-latency value for the selected SSB exceeding a latency threshold: decreasing the maximum number of PRACH repetitions or re-selecting the SSB; and applying a priority in which interference information takes precedence over latency information when indications conflict; and performing the random access based on the determined SSB index and maximum number of PRACH repetitions by transmitting Msg1 preambles on PRACH uplink resources mapped from the determined SSB index according to an SSB-to-random-access-occasion mapping signaled in SIB1, with the number of Msg1 transmissions capped by the maximum number of PRACH repetitions and terminated early upon receipt of a random access response (Msg2).
16 . The method of claim 15 , wherein the condition information is received in a system information block (SIB) broadcast by the gNB, the SIB including an SSB-indexed table having quantized values of interference, collision probability, latency, and offset, each encoded in 2 bits.
17 . The method of claim 16 , wherein determining the at least one parameter comprises applying a per-SSB offset to an RSRP threshold configured by the gNB to adjust the number of PRACH repetitions.
18 . The method of claim 17 , wherein the at least one parameter comprises a maximum number of PRACH repetitions, and the apparatus terminates Msg1 transmissions early when a random access response (Msg2) is received prior to completing all repetitions.
19 . The method of claim 18 , wherein determining the at least one parameter further comprises reducing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and random access occasions are shared among UEs in the cell, wherein the condition information includes an update periodicity, and the apparatus applies the condition information only during a validity duration indicated by the gNB.
20 . The method of claim 18 , wherein determining the at least one parameter further comprises increasing the number of PRACH repetitions when the received collision probability for a selected SSB index exceeds a collision threshold and the random access occasions are pseudo-randomly selected among UEs in the cell, wherein the condition information includes an update periodicity, and the apparatus applies the condition information only during a validity duration indicated by the gNB.

Description

RELATED APPLICATION This application was originally filed as a Finnish patent application no. 20226026, on 15 Nov. 2022, which is hereby incorporated in its entirety. TECHNICAL FIELD Various example embodiments relate generally to random access. BACKGROUND Random access is a procedure used by terminal devices to acquire connection to a network. It is important provide a reliable random access procedure with a high success rate. BRIEF DESCRIPTION According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. LIST OF THE DRAWINGS In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which FIG. 1 presents a network, according to an embodiment; FIG. 2 shows an example of initial access procedure, according to an embodiment; FIG. 3A shows transmission of SSBs, according to an embodiment; FIG. 3B shows a selection of SSB, according to some embodiments; FIGS. 4 and 5 illustrate methods, according to some embodiments; FIG. 6 shows different types of condition information and how they may be used, according to some embodiments; FIG. 7 illustrates an example table of condition information, according to an embodiment; FIG. 8 depicts a signaling flow diagram between user equipment and network node, according to some embodiments; FIG. 9 shows a method, according to an embodiment; and FIGS. 10 and 11 illustrate apparatuses, according to some embodiments. DESCRIPTION OF EMBODIMENTS The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrases “A or B” and “A and/or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. Embodiments described may be implemented in a radio system, such as one comprising at least one of the following radio access technologies (RATs): Worldwide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE). Term ‘eLTE’ here denotes the LTE evolution that connects to a 5G core. LTE is also known as evolved UMTS terrestrial radio access (EUTRA) or as evolved UMTS terrestrial radio access network (EUTRAN). A term “resource” may refer to radio resources, such as a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term “transmission” and/or “reception” may refer to wirelessly transmitting and/or receiving via a wireless propagation channel on radio resources The embodiments are not, however, restricted to the systems/RATs given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties. One example of a suitable communications system is the 5G system. The 3GPP solution to 5G is referred to as New Radio (NR). 5G has been envisaged to use multiple-input-multiple-output (MIMO) multi-antenna transmission techniques, more base stations or nodes than the current network deployments of LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller local area access nodes and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates. 5G will likely be comprised of more than one radio access technology/radio access network (RAT/RAN), each optimized for certain use cases and/or spectrum. 5G mobile communications may have a wider range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications, including vehicular safety