Random access technique

Abstract

A Random Access Technique is described. A first aspect of the technique relates to a method (300) performed by a radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs. The method (300) comprises determining (302) a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs. The method (300) further comprises transmitting (304), to the network node (200), a RA preamble, RAP, using the RO; and receiving (306), from the network node (200), a RA response, RAR, using the RA identifier.

Description

[0001] Telefonaktiebolaget LM Ericsson (publ) - 1 - 301-0298WO P112956WO01

[0002] Random Access Technique

[0003] Technical Field

[0004] The present disclosure relates to a technique for random access resource identification in a radio access network. More specifically, and without limitation, a method performed by a radio device and a method performed by a network node as well as corresponding radio device and network node are provided.

[0005] Background

[0006] Mobile communication standards such as those developed by the Third Generation Partnership Project (3GPP) and the O-RAN Alliance guide the evolution of radio access networks to meet ever-increasing demands for capacity, efficiency, and robustness.

[0007] In particular, network deployments are constantly optimized for improved performance, including faster connections, and more efficient resource usage. This is crucial for reliable performance, enhancing user experiences, supporting services, and facilitating the integration of diverse use cases into mobile networks.

[0008] However, existing radio access techniques can face difficulties in allocating and identifying random access resources, especially in scenarios with additional resource configurations or where different sets of resources must coexist without creating interference or ambiguity for connected devices.

[0009] Summary

[0010] Accordingly, there is a need for a random access resource identification technique that provides unambiguous and efficient handling of different sets of random access opportunities within a radio access network.

[0011] According to a first method aspect, a method performed by a radio device capable of performing random access to a network node of a radio access network using a first set of random access occasions and a second set of random access occasions is provided. The method includes determining a random access identifier for a random access occasion. The random access identifier is dependent on whether the random access occasion is in the first set or the second set of random access occasions. The method includes transmitting, to the network node, a random access preamble using the random access occasion. The method further includesTelefonaktiebolaget LM Ericsson (publ) -2 - 301-0298WO P112956WO01

[0012] receiving, from the network node, a random access response using the random access identifier.

[0013] The random access response may be received in response to the random access preamble.

[0014] By ensuring that the random access identifier depends on whether the random access occasion is drawn from the first set or the second set of random access occasions, embodiments of the radio device can reliably distinguish between different resource allocations. This distinction prevents collisions and confusion in identifying responses from the network node. As a result, embodiments of the method can perform the overall random access procedure faster, more robust and / or avoid unwanted contention.

[0015] The first method aspect may be implemented alone or in combination with any one of the second aspect.

[0016] According to a second method aspect, a method performed by a network node in a radio access network is provided. The method includes configuring a first set of random access occasions and a second set of random access occasions for random access by at least one radio device. The method includes receiving, from the radio device, a random access preamble on one of the random access occasions. The method includes determining, based on whether the received random access occasion is in the first set or the second set, a random access identifier for the received random access occasion. The method further includes transmitting, to the radio device, a random access response (e.g., addressed) using the determined random access identifier.

[0017] By configuring two distinct sets of random access occasions and assigning a specific identifier space based on whether the radio device uses the first or the second set, embodiments of the network node prevent ambiguity in its random access response. This delineation of RA identifier usage may resolve a temporal overlap in RO usage and thus can enable a reliable and collision-free RA procedure with the radio device.

[0018] The second method aspect may be implemented alone or in combination with any one of the embodiments disclosed herein. The second method aspect may further comprise any feature and / or any step disclosed in the context of the first method aspect, or a feature and / or step corresponding thereto, e.g., a receiver counterpart to a transmitter feature or step.Telefonaktiebolaget LM Ericsson (publ) -3 - 301-0298WO P112956WO01

[0019] As to a first method aspect, a method performed by a radio device capable of performing random access (RA) to a network node of a radio access network (RAN) using a first set of random-access occasions (ROs) and a second set of ROs is provided. The method comprises determining a random access identifier for a random-access occasion, wherein the random access identifier is dependent on whether the random-access occasion is in the first set or the second set of ROs. The method further comprises transmitting, to the network node, a random-access preamble (RAP) using the random-access occasion. The method further comprises receiving, from the network node, a random-access response (RAR) using the random access identifier.

[0020] The random-access response (RAR) may be received in response to the randomaccess preamble (RAP).

[0021] The random-access occasions (ROs) may also be referred to as random-access opportunities.

[0022] The determined random access identifier may be different for different randomaccess occasions. For example, different random access identifiers may be determined for random-access occasions that overlap in the time domain and / or that do not overlap in the frequency domain.

[0023] Herein, time domain or frequency domain may refer to temporal and frequency radio resources, respectively, of the radio access network (RAN) or used by the network node of the radio access network (RAN).

[0024] The random-access preamble (RAP) may be referred to as a first message, e.g., of a random access procedure. The random-access response (RAR) may be referred to as a second message, e.g., of a random access procedure. The random access procedure may comprise 2 steps or 4 steps.

[0025] The radio device may use the random access identifier to search for downlink control information ( DCI), e.g. on a physical downlink control channel (PDCCH) in a second message from the network node and / or in response to the random-access preamble (RAP).

[0026] Alternatively or additionally, the radio device may use the random access identifier to receive the random-access response (RAR), wherein a cyclic redundancy checkTelefonaktiebolaget LM Ericsson (publ) -4- 301-0298WO P112956WO01

[0027] (CRC) for the random-access response (RAR), for example for the downlink control information (DCI) scheduling the random-access response (RAR), is scrambled with the random access identifier.

[0028] Any random-access occasion (RO) may also be referred to as a random access channel (RACH) occasion, a random access channel (RACH) resource, or randomaccess resources (RA resources).

[0029] The first set of random-access occasions (ROs) may be different from the second set of random-access occasions (ROs). For example, the first set of random-access occasions (ROs) may be disjoint from the second set of random-access occasions (ROs).

[0030] The random-access occasions (ROs) may be radio resources in a combination of time (or temporal resources) and frequency (or frequency resources) of the network node, for example in a time-frequency grid of the network node.

[0031] Different random access identifiers may be determined for random-access occasions (ROs) that are equal or overlap in the time domain. Alternatively or additionally, the determined random access identifier may be dependent on a frequency domain of the random-access occasion. Alternatively or additionally, different random access identifiers may be determined for random-access occasions that are different in the frequency domain. For example, the randomaccess occasions may be offset in the frequency domain. Alternatively or additionally, a random access identifier determined for a random-access occasion from the first set may be different from a random access identifier determined for a random-access occasion from the second set.

[0032] The receiving of the random-access response (RAR) may comprise searching within a random-access response (RAR) window using the random access identifier.

[0033] The random-access response (RAR) window may be defined according to 3GPP TS 38.213, version 18.5.0 or later, for example Release 19, clause 8.2.

[0034] The first set of random-access occasions (ROs) may be semi-statically configured by the network node. For example, the first set of random-access occasions (ROs) may be semi-statically configured using a system information block 1 (SI Bl) for random access (RA). Alternatively or additionally, the second set of random-accessTelefonaktiebolaget LM Ericsson (publ) -5 - 301-0298WO P112956WO01

[0035] occasions (ROs) may comprise random-access occasions associated with network energy saving (NES) operations of the network node or the radio access network (RAN).

[0036] By distinguishing between legacy random-access occasions (ROs) and those intended for network energy saving (NES) operations, the two sets of randomaccess occasions (ROs) may enable the radio device to correctly derive and use the appropriate random access identifier for either set of random-access occasions, for example avoiding contention and ambiguity when both sets of occasions exist simultaneously.

[0037] The first set of random-access occasions (ROs) may be referred to as a legacy set, or the random-access occasions (ROs) in the first set may be referred to as legacy random-access occasions.

[0038] Alternatively or additionally, the second set of random-access occasions (ROs) may be referred to as a network energy saving (NES) set, or the random-access occasions (ROs) in the second set may be referred to as network energy saving (NES) random-access occasions.

[0039] The radio device may be referred to as an enhanced or capable radio device, for example a network energy saving (NES)-capable radio device, for example because the radio device is capable of performing random access (RA) using one or more random-access occasions of the second set.

[0040] By ensuring that the network energy saving (NES)-capable radio device can utilize two sets of random-access occasions with distinct random access identifiers, the radio device may avoid collisions or ambiguity in the random-access response (RAR) or in receiving the random-access response (RAR).

[0041] Alternatively or additionally, the random-access response (RAR) may be uniquely associated with the radio device, for example even if another radio device performs random access (RA) on a random-access occasion that overlaps in the time domain with the random-access occasion used by the radio device.

[0042] This may enable more flexible random-access adaptation while preventing ambiguity of the random access identifier between network energy saving (NES) random-access occasions or between a network energy saving (NES) random-Telefonaktiebolaget LM Ericsson (publ) -6 - 301-0298WO P112956WO01

[0043] access occasion and a legacy random-access occasion, and may thereby improve random-access efficiency.

[0044] The random-access occasion used for the transmission of the random-access preamble (RAP) may be from the second set of random-access occasions (ROs).

[0045] Alternatively or additionally, the random-access occasion used for the transmission of the random-access preamble (RAP) may be a network energy saving (NES) random-access occasion for network energy saving (NES) operation of the network node.

[0046] The random access identifier may be a random access radio network temporary identifier (RA-RNTI). Any random access identifier may be a random access radio network temporary identifier (RA-RNTI).

[0047] Herein, the words "index", "identifier", and "id" may be interpreted as synonymous. For example, the expressions may be interchanged or combined.

[0048] For example, the random access radio network temporary identifier (RA-RNTI) may be referred to as an identifier. The random access radio network temporary identifier (RA-RNTI) may be a function of multiple indices. The indices may be abbreviated by "id" or other names including "id".

[0049] The method may further comprise acquiring, from the network node, the first set of random-access occasions (ROs) and / or the second set of random-access occasions (ROs).

[0050] The acquiring may comprise receiving one or more configuration messages indicative of the first set of random-access occasions (ROs) and / or the second set of random-access occasions (ROs).

[0051] The radio device may determine the random access identifier that is dependent on the first set and the second set, for example that is different for the first set and the second set, only if the random-access occasion is from the second set of random-access occasions and overlaps in the time domain with one or more random-access occasions from the first set of random-access occasions.Telefonaktiebolaget LM Ericsson (publ) -7 - 301-0298WO P112956WO01

[0052] Restricting the identifier distinction to periods of time overlap can avoid unnecessary reconfiguration of the random access identifier space during nonoverlapping operation, minimizing complexity and conserving resources while still preventing random access identifier ambiguity or collisions during overlapping resources.

[0053] Hereinbelow, the numerical values are given as concrete examples, and not for limiting the invention. For example, any one of the numerical values range_s_id = 14, range_t_id = 80, range_f_id = 8, and range_ul_carrier_id = 2 for range sizes of indices can be changed by the skilled person as needed.

[0054] At least some variants of the embodiments may ensure that the value of the random access identifier may be unique, i.e., the set of values for the random access identifier for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0055] In a variant of any embodiment, the second set of random-access occasions (ROs) may be the set of network energy saving (NES) random-access occasions for network energy saving (NES).

[0056] The random access identifier may be distinguished for the first set of randomaccess occasions (ROs) and the second set of random-access occasions (ROs) by an offset of one index in a joint index for the random access identifier.

[0057] The one index in the joint index may be a sub-significant index. For example, the one index may be an index other than the most significant index. Moreover, the one index may not be the least significant index.

[0058] The one index may be an index for the frequency domain of the random-access occasion. For example, the one index may be an index indicative of a location in the frequency domain for the random-access occasion.

[0059] The random access identifier may be determined as

[0060] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_first_set_id

[0061] + range_f_id x ul_carrier_id)]

[0062] for the first set of random-access occasions, and asTelefonaktiebolaget LM Ericsson (publ) -8 - 301-0298WO P112956WO01

[0063] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_second_set_id+f_number_in_first_set + range_f_id x ul_carrier_id)]

[0064] for the second set of random-access occasions.

[0065] Herein, the index f_id for the frequency domain for a random-access occasion in the first set of ROs (e.g., the non-NES ROs) may be referred to as f_first_set_id. Alternatively or additionally, the index f_id for the frequency domain for a random-access occasion in the second set of ROs (e.g., the NES ROs) may be referred to as f_second_set_id.

[0066] The one index for the frequency domain may be limited. For example, a range of the one frequency domain index within the joint index for the random access identifier may be disjoint for the first set and the second set of random-access occasions.

[0067] It may hold that

[0068] 0 <= f_first_set_id < f_number_in_first_set

[0069] and that

[0070] 0 <= f_second_set_id+f_number_in_first_set < range_f_id.

[0071] This option of the embodiment can ensure that the value of the random access identifier is unique, i.e., the set of values for the random access identifier for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0072] The random access identifier may be determined as

[0073] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_id

[0074] + range_f_id x ul_carrier_id)]

[0075] f first_offset, for the first set of ROs

[0076] (second_offset, for the second set of ROs

[0077] optionally wherein first_offset = 0 and second_offset = range_s_id x range_t_id x f_number_in_first_set.

[0078] By way of example, f_number_in_first_set = f_Nnon-NES, that is the maximum number of locations in the frequency domain for the non-network energy saving (non-NES) random-access occasions.Telefonaktiebolaget LM Ericsson (publ) -9 - 301-0298WO P112956WO01

[0079] For example: For f_ id = f_second_set_id (e.g., for a RO in the second set of ROs): RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_second_set_id

[0080] + range_f_id x ul_carrier_id)]

[0081] + range_s_id x range_t_id x f_number_in_first_set

[0082] or

[0083] RA identifier = s_id + range_s_id x [t_id + range_t_id x (f_set_id

[0084] + range_f_id x ul_carrier_id)]

[0085] + constant

[0086] wherein constant = l+range_s_id x range_t_id x f_number_in_first_set.

[0087] An index f_id for determining the random access identifier according to the second set may be based on an index of the random-access occasion in the frequency domain according to the second set and a parameter related to the number of random-access occasions in the frequency domain based on the first set.

[0088] The determined random access identifier may be a joint index of indices that define the random-access occasion.

[0089] The joint index may be a function RA identifier = RA identifier(id 1, ...) that is represented, representable, or approximated by

[0090] RA identifier = id i + rangejdi x (

[0091] id? + rangejdz x (

[0092] ids + rangejds x (

[0093] id4 + optionally further indices

[0094] )

[0095] )

[0096] )

[0097] + constant.

[0098] The joint index may be a function of indices idn(for n = 1, ...), which are also referred to as the indices within the joint index. The indices

[0099] idn(for n = 1, ...)

[0100] within the joint index may be variables of the joint index. The range sizes range_idn(for n = 1, ...)Telefonaktiebolaget LM Ericsson (publ) - 10- 301-0298WO P112956WO01

[0101] may be parameters of the joint index.

[0102] Alternatively or additionally, the joint index may be recursively defined, for example by applying the replacement at least once:

[0103] RA identifier = id i + constant

[0104] Replacement: "

[0105]

[0106] " " "

[0107] The random access may be a joint index of at least one of an index s_id of a first OFDM symbol of the random-access occasion, an index t_id of a time domain of the random-access occasion, an index f_id of a frequency domain of the randomaccess occasion, and an index ul_carrier_id of an uplink carrier of the randomaccess occasion.

[0108] - The index t_id may optionally be an index of a temporal radio resource of the random-access occasion, a slot of the random-access occasion, a subframe of the random-access occasion, or a radio frame of the randomaccess occasion.

[0109] - The index f_id may optionally be an index of a subcarrier of the randomaccess occasion or a radio block of the random-access occasion.

[0110] - The index ul_carrier_id may optionally be an index of a non- supplementary uplink (NUL) carrier or a supplementary uplink (SUL) carrier.

[0111] One or each index idnof the indices within the random access identifier may be cyclic within its range 0 < idn< range_idnfor n = 1, ... .

[0112] Alternatively or additionally, the random access identifier may be a function RA identifier^.., idn, ...) = RA identifier^.., idnmod range_idn, ...) with a modulo operation applied to one or each index idnwithin the random access identifier.

[0113] The first-mentioned index within the joint index may be referred to as the least significant index. The last-mentioned index within the joint index may be referred to as the most significant index. Within the joint index, any index that is not the most significant index may be referred to as a sub-significant index.

[0114] One or each index idnof the indices within the random access identifier may be limited to its range 0 < idn< range_idnfor n = 1, ... .Telefonaktiebolaget LM Ericsson (publ) - 11 - 301-0298WO P112956WO01

[0115] Alternatively or additionally, an index within the joint index for the random access identifier may be limited to a first frequency range and a second frequency range for the first set of random-access occasions and the second set of random-access occasions, respectively. For example, the first frequency range and the second frequency range may be subsets within a full frequency range 0 < f_id < range_f_id of the index f_id for the frequency domain.

[0116] In a variant of any embodiment, one index within the random access identifier may be offset and / or a modulo operator may be applied to the index within the random access identifier. This can reduce the probability of a collision without limiting the index within the random access identifier.

[0117] An index, optionally f_id, within the random access identifier as a joint index may be offset for the second set of random-access occasions relative to the same index within the random access identifier used for the first set of random-access occasions.

[0118] For example, the random access identifier may be determined as

[0119] RA identifier (s_id, t_id, f_id, ul_carrier_id)

[0120] for the first set of random-access occasions, and

[0121] RA identifier = RA identifier (s_id, t_id, f_id + f_offset, ul_carrier_id) for the second set of random-access occasions.

[0122] The f_offset may be equal to the number of locations in the frequency domain for random-access occasions in the first set of random-access occasions, namely f_number_in_first_set.

[0123] Alternatively or additionally, for the second set of random-access occasions, the random access identifier may be determined as

[0124] = 1 + s_id + range_s_id x [t_id + range_t_id x (modulo (f_id+f_number_in_first_set, range_f_id) + range_f_id x ul_carrier_id)].

[0125] Optionally, f_id may be an index of the frequency domain for the second set of random-access occasions. For example, f_id may be f_second_set_id for the frequency domain for the second set of random-access occasions.

[0126] For example, for a network energy saving (NES) set of random-access occasions, the random access identifier may be determined asTelefonaktiebolaget LM Ericsson (publ) - 12- 301-0298WO P112956WO01

[0127] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (modulo (f_idNES+Nnon-NES, range_f_id) + range_f_id x ul_carrier_id)L

[0128] wherein Nnon-NEs 'sthe maximum number of locations in the frequency domain for non-network energy saving (non-NES) random-access occasions.

[0129] The receiving may comprise the radio device monitoring for the random-access response (RAR) only in a search space indicated by the determined random access identifier distinct for the second set, responsive to transmitting the random-access preamble (RAP) using the random-access occasion in the second set of randomaccess occasions.

[0130] Confining the radio device's random-access response (RAR) monitoring to the random access identifier derived specifically for the second set ensures embodiments of the radio device can decode the correct random-access response (RAR) when multiple responses may be present, for example legacy and network energy saving (NES), and prevents false detections or missed random-access responses.

[0131] The radio device may ignore any random-access response (RAR) scrambled with a random access identifier corresponding to the first set of random-access occasions when the radio device has used the random-access occasion of the second set for transmitting the random-access preamble (RAP).

[0132] By disregarding responses not addressed to the network energy saving (NES)-capable second set, the radio device avoids reacting to irrelevant random-access responses intended for other radio devices or legacy procedures, thus improving reliability and preserving correct protocol operation under concurrent resource usage.

[0133] Embodiments of the method may unify random-access procedures under an extended identifier space. Alternatively or additionally, by consistently applying the extended identifier scheme regardless of time overlap, the radio device simplifies internal handling of random-access transmissions, prevents potential confusion from switching repeatedly between schemes, and / or ensures futureproofing if additional resource adaptations are introduced.

[0134] The radio device may selectively transmit on the second set of random-access occasions only if indicated by the network node, and the radio device may revertTelefonaktiebolaget LM Ericsson (publ) - 13- 301-0298WO P112956WO01

[0135] to the first set of random-access occasions in the absence of the indication by the network node.

[0136] By allowing the network node to (e.g., dynamically) activate or deactivate the second set of random-access resources, embodiments of the method can dynamically match changing traffic or energy-saving needs, and / or efficiently balancing network load and sleep intervals without compromising an ability of the radio device to perform random access.

[0137] As to a second method aspect, a method performed by a network node in a radio access network (RAN) is provided. The method comprises configuring a first set of random-access occasions (ROs) and a second set of random-access occasions for random access (RA) by at least one radio device. The method further comprises receiving, from the radio device, a random-access preamble (RAP) on one of the random-access occasions. The method further comprises determining, based on whether the received random-access occasion is in the first set or the second set, a random access identifier for the received random-access occasion. The method further comprises transmitting, to the radio device, a random-access response (RAR) addressed using the determined random access identifier.

[0138] By determining and using a random access identifier that is dependent on whether the radio device used the first or second set of random-access occasions, embodiments of the network node can ensure that random-access responses are unambiguously addressed. This can avoid collisions or contention that might otherwise arise when random-access occasions coexist in the time domain, thus improving reliability and efficiency of random access.

[0139] Configuring the first set and the second set may comprise sending, for example broadcasting, one or more configuration messages to the at least one radio device.

[0140] The random access identifier may be distinguished for the first set of randomaccess occasions and the second set of random-access occasions by an offset of one index in a joint index for the random access identifier.

[0141] The one index may be an index for the frequency domain of the random-access occasion. For example, the one index may be an index indicative of a location in the frequency domain for the random-access occasion.Telefonaktiebolaget LM Ericsson (publ) - 14- 301-0298WO P112956WO01

[0142] The method may further comprise changing the random access identifier to be different for two random-access occasions that overlap in the time domain.

[0143] Optional ly, the two random-access occasions that overlap in the time domain may differ in the frequency domain.

[0144] Thereby, embodiments can prevent reuse of the same random access identifier for temporally overlapping random-access occasions.

[0145] By ensuring distinct random access identifiers for overlapping resources, embodiments of the network node can eliminate an ambiguity in addressing random-access responses (RARs) when multiple random-access occasions intersect in time, thus improving the efficiency of random access signaling and reducing collision rates.

[0146] The method may further comprise indicating the second set of random-access occasions via a configuration message sent to the radio device.

[0147] Alternatively or additionally, the method may further comprise activating or deactivating the second set of random-access occasions for the radio device, optionally based on a trigger, and the network node may revert to only the first set of random-access occasions if the trigger is absent.

[0148] Dynamically activating or deactivating the second set of random-access occasions allows embodiments of the network node to flexibly control random-access resources in response to changing traffic or operational requirements (as examples of the trigger), supporting efficient resource utilization while maintaining reliable connectivity.

[0149] Any aspect may enhance the RA identifier (e.g., RA-RNTI) for additional RACH resource, i.e., the ROs of the second set of ROs.

[0150] The second set of ROs may be related to network energy savings (NES) or any other additional random-access resources.

[0151] Any aspect of the technique may be applied in the context of 3GPP New Radio (NR) or beyond 5G.Telefonaktiebolaget LM Ericsson (publ) - 15- 301-0298WO P112956WO01

[0152] The technique may be implemented in accordance with a 3GPP specification, e.g., for 3GPP Release 18 or future Release 19, e.g. based on or by modifying 3GPP TS 38.321, version 18.4.0 (e.g., clause 5.1.3) and / or 3GPP TS 38.213, version 18.5.0. Alternatively or in addition, embodiments of the technique may address shortcomings of, or provide an alternative solution to, proposals in the 3GPP document Rl-2410273 (on Adaptation of common signal channel transmissions) for 3GPP RANI #119, Orlando, Nov 2024.

[0153] Any radio device may be a user equipment (UE), e.g., according to a 3GPP specification. The radio device and the RAN may be wirelessly connected in an uplink (UL) and / or a downlink (DL) through a Uu interface. Alternatively or in addition, the any radio link may be relayed between proximal radio devices, e.g., a remote radio device and the relay radio device, optionally using a PC5 interface. Services provided using the SL or the PC5 interface may be referred to as proximity services (ProSe).

[0154] The radio device and / or the network node and / or the RAN may form, or may be part of, a radio network, e.g., according to the Third Generation Partnership Project (3GPP) or according to the standard family IEEE 802.11 (Wi-Fi). The first method aspect and the second method aspect may be performed by one or more embodiments of the radio device and the RAN (e.g., the network node, such as a base station) or the relay radio device, respectively.

[0155] The RAN may comprise one or more network node (e.g., base stations), e.g., performing the second method aspect. Alternatively or in addition, the radio network may be a vehicular, ad hoc and / or mesh network comprising two or more radio devices, e.g., acting as the remote radio device and / or the relay radio device.

[0156] Any of the radio devices may be a 3GPP user equipment (UE) or a Wi-Fi station (STA). The radio device may be a mobile or portable station, a device for machinetype communication (MTC), a device for narrowband Internet of Things (NB-loT) or a combination thereof. Examples for the UE and the mobile station include a mobile phone, a tablet computer and a self-driving vehicle. Examples for the portable station include a laptop computer and a television set. Examples for the MTC device or the NB-loT device include robots, sensors and / or actuators, e.g., in manufacturing, automotive communication and home automation. The MTC device or the NB-loT device may be implemented in a manufacturing plant, household appliances and consumer electronics.Telefonaktiebolaget LM Ericsson (publ) - 16- 301-0298WO P112956WO01

[0157] Whenever referring to the RAN, the RAN may be implemented by one or more embodiments of the network node (e.g., base stations). The radio device may be wirelessly connected or connectable (e.g., according to a radio resource control, RRC, state or active mode) with at least one network node of the RAN.

[0158] The network node (e.g., a base station) may encompass any station that is configured to provide radio access to any of the radio devices. The base station may be a cell, a transmission and reception point (TRP), a central unit (CU), a distributed unit (DU), a radio access node or an access point (AP). The base station and / or the relay radio device may provide a data link to a host computer providing user data to the (e.g., remote) radio device or gathering user data from the (e.g., remote) radio device. Examples for the base stations may include a 3G base station or Node B (NB), 4G base station or eNodeB (eNB), a 5G base station or gNodeB (gNB), a Wi-Fi AP and a network controller (e.g., according to Bluetooth, ZigBee or Z-Wave).

[0159] The RAN may be implemented according to the Global System for Mobile Communications (GSM), the Universal Mobile Telecommunications System (UMTS), 3GPP Long Term Evolution (LTE) and / or 3GPP New Radio (NR).

[0160] Any aspect of the technique may be implemented on a Physical Layer (PHY), a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, a packet data convergence protocol (PDCP) layer, and / or a Radio Resource Control (RRC) layer of a protocol stack for the radio communication.

[0161] Herein, referring to a protocol of a layer may also refer to the corresponding layer in the protocol stack. Vice versa, referring to a layer of the protocol stack may also refer to the corresponding protocol of the layer. Any protocol may be implemented by a corresponding method.

[0162] As to another aspect, a computer program product is provided. The computer program product comprises program code portions for performing any one of the steps of the first and / or second method aspect disclosed herein when the computer program product is executed by one or more computing devices. The computer program product may be stored on a computer-readable recording medium. The computer program product may also be provided for download, e.g., via the radio network, the RAN, the Internet and / or the host computer.Telefonaktiebolaget LM Ericsson (publ) - 17- 301-0298WO P112956WO01

[0163] Alternatively, or in addition, the method may be encoded in a Field-Programmable Gate Array (FPGA) and / or an Application-Specific Integrated Circuit (ASIC), or the functionality may be provided for download by means of a hardware description language.

[0164] As to a first device aspect, a radio device capable of performing random access (RA) to a network node of a radio access network (RAN) using a first set of randomaccess occasions (ROs) and a second set of random-access occasions is provided. The radio device comprises memory operable to store instructions and processing circuitry operable to execute the instructions. The radio device is operable to determine a random access identifier for a random-access occasion, wherein the random access identifier is dependent on whether the random-access occasion is in the first set or the second set of random-access occasions. The radio device is further operable to transmit, to the network node, a random-access preamble (RAP) using the random-access occasion. The radio device is further operable to receive, from the network node, a random-access response (RAR) using the random access identifier.

[0165] As to another first device aspect, a radio device capable of performing random access (RA) to a network node of a radio access network (RAN) using a first set of random-access occasions (ROs) and a second set of random-access occasions is provided. The radio device is configured to determine a random access identifier for a random-access occasion, wherein the random access identifier is dependent on whether the random-access occasion is in the first set or the second set of random-access occasions. The radio device is further configured to transmit, to the network node, a random-access preamble (RAP) using the random-access occasion. The radio device is further configured to receive, from the network node, a random-access response (RAR) using the random access identifier.

[0166] As to a second device aspect, a network node is provided. The network node comprises memory operable to store instructions and processing circuitry operable to execute the instructions. The network node is operable to configure a first set of random-access occasions (ROs) and a second set of random-access occasions for random access (RA) by at least one radio device. The network node is further operable to receive, from the radio device, a random-access preamble (RAP) on one of the random-access occasions. The network node is further operable to determine, based on whether the received random-access occasion is in the first set or the second set, a random access identifier for the received random-accessTelefonaktiebolaget LM Ericsson (publ) - 18- 301-0298WO P112956WO01

[0167] occasion. The network node is further operable to transmit, to the radio device, a random-access response addressed using the determined random access identifier.

[0168] As to another second device aspect, a network node of a radio access network (RAN) is provided. The network node is configured to configure a first set of random-access occasions (ROs) and a second set of random-access occasions for random access (RA) by at least one radio device. The network node is further configured to receive, from the radio device, a random-access preamble (RAP) on one of the random-access occasions. The network node is further configured to determine, based on whether the received random-access occasion is in the first set or the second set, a random access identifier for the received random-access occasion. The network node is further configured to transmit, to the radio device, a random-access response addressed using the determined random access identifier.

[0169] As to a still further aspect a communication system, e.g. including a host computer, is provided. The host computer comprises a processing circuitry configured to provide user data. The host computer further comprises a communication interface configured to forward the user data to a cellular network (e.g., the RAN and / or the network node) for transmission to the radio device (e.g., a UE). A processing circuitry of the cellular network is configured to execute any one of the steps of the second method aspect. Alternatively or in addition, the radio device comprises a radio interface and processing circuitry, which is configured to execute any one of the steps of the first method aspect.

[0170] The communication system may further include the UE. Alternatively, or in addition, the cellular network may further include one or more base stations configured for radio communication with the UE and / or to provide a data link between the UE and the host computer using the first and / or second method aspects.

[0171] The processing circuitry of the host computer may be configured to execute a host application, thereby providing the user data and / or any host computer functionality described herein. Alternatively, or in addition, the processing circuitry of the UE may be configured to execute a client application associated with the host application.Telefonaktiebolaget LM Ericsson (publ) - 19 - 301-0298WO P112956WO01

[0172] Any one of the devices, the radio device, the UE, the network node, the base station, the communication system or any node or station for embodying the technique may further include any feature disclosed in the context of the method aspect, and vice versa. Particularly, anyone of the units and modules disclosed herein may be configured to perform or initiate one or more of the steps of the method aspect.

[0173] Brief Description of the Drawings

[0174] Further details of embodiments of the technique are described with reference to the enclosed drawings, wherein:

[0175] Fig. 1 shows a schematic block diagram of an embodiment of a device for performing random access to a radio access network;

[0176] Fig. 2 shows a schematic block diagram of an embodiment of a device for providing random access at a radio access network;

[0177] Fig. 3 shows a flowchart for a method of performing random access, which method may be implementable by the device of Fig. 1;

[0178] Fig. 4 shows a flowchart for a method of providing random access, which method may be implementable by the device of Fig. 2;

[0179] Fig. 5 schematically illustrates an example of a radio network comprising embodiments of the devices of Figs. 1 and 2 for performing the methods of Figs. 3 and 4, respectively;

[0180] Fig. 6 schematically illustrates a signaling diagram resulting from embodiments of the devices of Figs. 1 and 2 performing embodiments of the methods of Figs. 3 and 4, respectively;

[0181] Fig. 7 schematically illustrates a radio resources of a radio access network in the time domain comprising random access occasions (ROs);

[0182] Fig. 8 schematically illustrates an example of a first set of ROs and a second set of ROs for the radio communication of embodiments of the devices of Figs. 1 and 2 performing the methods of Figs. 3 and 4, respectively;Telefonaktiebolaget LM Ericsson (publ) -20- 301-0298WO P112956WO01

[0183] Fig. 9 schematically illustrates a ROs of the first set and the second set in a timefrequency domain;

[0184] Fig. 10 shows a schematic block diagram of a radio device embodying the device of Fig. 1;

[0185] Fig. 11 shows a schematic block diagram of a radio access network, e.g., network node, embodying the device of Fig. 2; and

[0186] Fig. 12 schematically illustrates an example telecommunication network connected via an intermediate network to a host computer.

[0187] Detailed Description

[0188] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as a specific network environment in order to provide a thorough understanding of the technique disclosed herein. It will be apparent to one skilled in the art that the technique may be practiced in other embodiments that depart from these specific details. Moreover, while the following embodiments are primarily described for a New Radio (NR) or 5G implementation, it is readily apparent that the technique described herein may also be implemented for any other radio communication technique, including a Wireless Local Area Network (WLAN) implementation according to the standard family IEEE 802.11, 3GPP LTE (e.g., LTE-Advanced or a related radio access technique such as MulteFire), for Bluetooth according to the Bluetooth Special Interest Group (SIG), particularly Bluetooth Low Energy, Bluetooth Mesh Networking and Bluetooth broadcasting, for Z-Wave according to the Z-Wave Alliance or for ZigBee based on IEEE 802.15.4.

[0189] Moreover, those skilled in the art will appreciate that the functions, steps, units and modules explained herein may be implemented using software functioning in conjunction with a programmed microprocessor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP) or a general purpose computer, e.g., including an Advanced RISC Machine (ARM). It will also be appreciated that, while the following embodiments are primarily described in context with methods and devices, the invention may also be embodied in a computer program product as well as in a system comprising atTelefonaktiebolaget LM Ericsson (publ) -21- 301-0298WO P112956WO01

[0190] least one computer processor and memory coupled to the at least one processor, wherein the memory is encoded with one or more programs that may perform the functions and steps or implement the units and modules disclosed herein.

[0191] Fig. 1 schematically illustrates a block diagram of an embodiment of a device for performing random access. The device is generically referred to by reference sign 100.

[0192] The device 100 comprises the modules indicated in Fig. 1, e.g. for performing corresponding steps of the first method aspect and / or for implementing the first device aspect.

[0193] Any of the modules of the device 100 may be implemented by units configured to provide the corresponding functionality.

[0194] For example, the device 100 comprises a RA identifier determination module 102 that determines a RA identifier for a RA occasion when the RA occasion is in a first set of RA occasions or a second set of RA occasions. The device 100 comprises a RAP transmission module 104 that transmits a RA preamble to a network node. The device 100 comprises a RAR reception module 106 that receives a RA response using the RA identifier.

[0195] The device 100 may also be referred to as, or may be embodied by, the radio device (or briefly: UE). The radio device 100 and the network node may be in direct radio communication, e.g., at least for the transmission of the RAP and the reception of the RAR. The network node may be embodied by the following device 200. The radio device 100 and the network node 200 may be in direct radio communication, for example, at least for transmitting the RA preamble from the radio device 100 to the network node 200, and for receiving the RA response from the network node 200 at the radio device 100. The network node 200 may be embodied by the below-mentioned device 200.

[0196] Fig. 2 schematically illustrates a block diagram of an embodiment of a device for providing or supporting random access. The device is generically referred to by reference sign 200.Telefonaktiebolaget LM Ericsson (publ) -22- 301-0298WO P112956WO01

[0197] The device 200 comprises the modules indicated in Fig. 2, e.g. for performing corresponding steps of the second method aspect and / or for implementing the second device aspect.

[0198] For example, the device 200 comprises a RO set configuration module 201 that configures a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device. The device 200 comprises a RAP reception module 204 that receives, from the at least one radio device, a randomaccess preamble, RAP, on one of the ROs. The device 200 comprises an RA identifier determination module 205 that determines, based on whether the received RO is in the first set or the second set, an RA identifier for the received RO. The device 200 further comprises an RAR transmission module 206 that transmits, to the radio device, a random-access response addressed using the determined RA identifier.

[0199] Any of the modules of the device 200 may be implemented by units configured to provide the corresponding functionality.

[0200] The device 200 may also be referred to as, or may be embodied by, the network node (or briefly: gNB). The radio device and the network node 200 may be in direct radio communication, e.g., at least for the reception of the RAP and the transmission of the RAR. The network node may be embodied by the above device 100. For example, the radio device 100 may be embodied by the device discussed in Fig. 1.

[0201] Fig. 3 shows an example flowchart for a method 300 according to the first aspect.

[0202] The method comprises the steps indicated in Fig. 3.

[0203] The method 300 may be performed by the device 100. For example, the modules 102, 104 and 106 may perform the steps 302, 304 and 306, respectively.

[0204] Fig. 4 shows an example flowchart for a method 400 according to the second aspect.

[0205] The method comprises the steps indicated in Fig. 4.Telefonaktiebolaget LM Ericsson (publ) -23- 301-0298WO P112956WO01

[0206] The method 400 may be performed by the device 200. For example, the modules 201, 204, 205, and 206 may perform the steps 401, 404, 405, and 406, respectively.

[0207] In any aspect, the technique may be applied to uplink (UL), downlink (DL) or direct communications between radio devices, e.g., device-to-device (D2D) communications or sidelink (SL) communications.

[0208] Each of the random-accessing station 100 and random-accessed station 200 may be a radio device or a base station. Herein, any radio device may be a mobile or portable station and / or any radio device wirelessly connectable to a base station or RAN, or to another radio device. For example, the radio device may be a user equipment (UE), a device for machine-type communication (MTC) or a device for (e.g., narrowband) Internet of Things (loT). Two or more radio devices may be configured to wirelessly connect to each other, e.g., in an ad hoc radio network or via a 3GPP SL connection. Furthermore, any base station may be a station providing radio access, may be part of a radio access network (RAN) and / or may be a node connected to the RAN for controlling the radio access. For example, the base station may be an access point, for example a Wi-Fi access point.

[0209] The radio spectrum shared by multiple RATs may be an unlicensed spectrum.

[0210] Herein, a list of the form A, B, and / or C (also written as A, B and / or C) may correspond to at least one or each of A, B, and C, i.e., A and / or B and / or C.

[0211] An example of a radio access network 500 is shown in Fig. 5, providing a communication environment in which a network node 200 and a radio device 100 interact. The radio access network 500 forms a logical and / or physical infrastructure that enables uplink and downlink communications between the network node 200 and the radio device 100.

[0212] A coverage area 201 (e.g., a cell) envelops the network node 200, signifying the geographic region or beam in which the network node 200 is capable of serving the radio device 100. This coverage area 201 extends to wherever the network node 200 can reliably transmit and receive radio signals so that the radio device 100 may access network services.Telefonaktiebolaget LM Ericsson (publ) -24- 301-0298WO P112956WO01

[0213] A radio device 100 resides within the coverage area 201 and can initiate random access procedures to establish or maintain connectivity. The radio device 100 transmits a random-access preamble RAP to notify the network node 200 of an imminent access attempt. Due to the positioning of the radio device 100 within the coverage area 201, an optimized link budget enables reliable exchange of radio signals for initial access or ongoing service.

[0214] A network node 200, depicted in the center of the coverage area 201, detects 404 the random-access preamble RAP and responds 406 to the radio device 100 using a random-access response RAR. By transmitting 406 the random-access response RAR, the network node 200 allocates resources and provides scheduling instructions, e.g. improving a collision-free, synchronized communication flow with the radio device 100.

[0215] Any embodiment of any aspect may relate to energy consumption of the RAN 500 (also abbreviated by NW). For example, the second set of ROs may be dedicated to improve energy consumption.

[0216] NW power consumption in NR has increased significantly compared to LTE, partly due to higher bandwidth (BW) and massive number of antennas. This is still evident even if there are no UEs present in a cell. Although there is no UL or DL transmission between a specific UE and a gNB in idle mode, the gNB still needs to periodically transmit signals, such as SSB and broadcast system information, e.g., SI Bl. For example, SSBs can be configured with 20 ms periodicity, and SIB1 can be configured with 160 ms periodicity. In addition, the gNB also needs to periodically monitor the preambles from a UE to support random access, which implies that the receiver components of the gNB need to be turned on periodically, e.g., every 10 ms or less. Hence, although increasing the sleep time of a gNB can reduce the NW energy consumption, the sleep time of the gNB is constrained by the periodicity of transmit and receive.

[0217] A signaling diagram 600 of Fig. 6 illustrates a random-access procedure carried out between a radio device 100 on the left side and a network node 200 on the right side, wherein the radio device 100 is labeled "UE," and the network node 200 is labeled "eNB" without limitation.

[0218] A system information block SIB2 is shown at the top of the signaling diagram 600. The system information block SIB2 provides initial parameters that the radioTelefonaktiebolaget LM Ericsson (publ) -25- 301-0298WO P112956WO01

[0219] device 100 uses to prepare for a random-access preamble. This broadcast transmission benefits the radio device 100 by letting it acquire consistent network parameters beforehand.

[0220] A random-access preamble PRACH preamble (RAP or Msgl) is next in the flow of the signaling diagram 600. The radio device 100 sends this random-access preamble to the network node 200 in order to initiate synchronization and resource allocation. The preamble triggers the subsequent response from the network node 200.

[0221] A random-access response RAR (or Msg2) follows after the random-access preamble in Fig. 6. The network node 200 transmits 406 this random-access response, providing timing adjustments and an uplink grant for a subsequent message. The random-access response appears within a specified RAR window visible on the diagram 600, ensuring that the radio device 100 listens for the response during the correct time interval.

[0222] A radio resource control connection request RRC Connection Request (Msg3) operates just after the random-access response RAR (Msg2). This connection request allows the radio device 100 to indicate a need for further signaling and channel resources. The network node 200 then processes the request and prepares to respond with more detailed configuration.

[0223] A hybrid automatic repeat request feedback HARQ ACK for Msg3 is also shown on the signaling diagram 600. This HARQ acknowledgment confirms the proper reception of the RRC Connection Request by the network node 200. The feedback supports reliability since the radio device 100 can retry if the acknowledgment is not received.

[0224] A contention resolution timer appears between the connection request and a message labeled CR + RRC Connection Setup (Msg4). During this timer, the radio device 100 awaits instructions or further messages from the network node 200. This timing mechanism resolves collisions, maintaining orderly access when multiple devices attempt random access simultaneously.

[0225] A radio resource control connection setup CR + RRC Connection Setup (Msg4) follows immediately afterward. The network node 200 provides explicit configuration for the radio device 100, including bandwidth allocation andTelefonaktiebolaget LM Ericsson (publ) -26- 301-0298WO P112956WO01

[0226] scheduling details needed to proceed. This step finalizes the initial access and prepares the radio device 100 for communication.

[0227] Another hybrid automatic repeat request feedback HARQ ACK for Msg4 appears in the signaling diagram 600. This second HARQ acknowledgment confirms that the radio device 100 has successfully received the connection setup, promoting higher reliability throughout the setup process.

[0228] A further message labeled DCI 0 (UL Grant) is indicated in the diagram 600 after the RRC Connection Setup. The network node 200 uses this scheduling grant to inform the radio device 100 of uplink resources for transmitting a final confirmation of the connection or carrying user data. This improves efficiency, as the radio device 100 is promptly allocated sufficient resources.

[0229] An RRC Connection Setup Complete message concludes the illustrated procedure in Fig. 6. By sending this final acknowledgment, the radio device 100 confirms successful establishment of the RRC connection, ensuring the system can now handle user data or additional signaling at the requested quality of service level.

[0230] Fig. 7 schematically illustrates a RA channel (RACH) configuration (i.e., a configuration of the ROs) in the time domain.

[0231] The RACH in 5G is a fundamental uplink channel used by UE to establish communication with the gNB. It is part of the Random-Access Procedure, which enables initial access, connection re-establishment, handovers, and other scenarios where the UE needs to synchronize with the network or request resources. RACH resources are configured via higher layers (e.g. system information) and typical RACH resources may occur periodically as shown in Fig. 7, where each cell corresponds to a slot or a subframe. After sending a RACH, UE monitors for a RACH response in a search space (e.g. ra-searchSpace, that is configured by higher layers), and if it does not receive a response within a predetermined amount of time, the UE tries to send RACH again.

[0232] In Fig. 7 uplink resources (i.e., ROs) for random access are illustrated. E.g., one RACH occasion (i.e., RO) is in subframe #4 of each radio frame.Telefonaktiebolaget LM Ericsson (publ) - T1 - 301-0298WO P112956WO01

[0233] Any embodiment of any aspect, e.g., in the determining steps 302 and 405 may determine a Random Access (RA) Radio Network Temporary Identifier (RA-RNTI) as an example of the RA identifier.

[0234] In an embodiment, for the first set of ROs, and / or as a baseline RA of the RA identifier, may be determined as specified in TS 38.213 or as described below.

[0235] The RA-RNTI, associated with the PRACH occasion (i.e., RO) in which the Random Access Preamble (RAP) is transmitted 304 or the RA-RNTI associated with the last valid PRACH occasion in the set of PRACH occasions (as specified in TS 38.213) for Msgl repetition, is computed as:

[0236] RA — RNTI = 1 + s_id + 14 x t_id + 14 x 80 x f_id

[0237] + 14 x 80 x 8 x ul_carrier_id

[0238] wherein s_id is the index of the first OFDM symbol of the PRACH occasion (0 < s_id < 14), t_id is the index of the first slot of the PRACH occasion in a system frame (0 < t_id < 80), where the subcarrier spacing to determine t_id is based on the value of p specified in clause 5.3.2 in TS 38.211 [8] for p = {0, 1, 2, 3}, and for p = {5, 6}, t_id is the index of the 120 kHz slot in a system frame that contains the PRACH occasion (0 < t_id < 80), f_id is the index of the PRACH occasion in the frequency domain (0 < f_id < 8), and ul_carrier_id is the UL carrier used for Random Access Preamble transmission (0 for NUL carrier, and 1 for SUL carrier). The range of all RNTI can be found in TS38.321, version 18.1.0 - 7.1, as follows

[0239] Table 7.1-1: RNTI values

[0240]

[0241] The baseline RA identifiers may be associated to legacy RACH occasions (i.e., RO of the first set). Up until Release 18, versions of the 3GPP specification (see 38.331 version 18.0.0), PRACH resources semi-statically configured in SIB1 may be updated in by the NW via the System Information Update procedure. If theTelefonaktiebolaget LM Ericsson (publ) -28- 301-0298WO P112956WO01

[0242] RACH configuration info in the SIB1 changes, an SI update will be signalled via the paging DCI short message mechanism, in all POs for the current cell during a SI modification period to ensure the info is received by all UEs camping on the cell. The actual change takes place after the SI modification period.

[0243] In any embodiment, the ROs in the second set may be additional RACH occasions (ROs), e.g. for Network Energy Saving (NES).

[0244] In 3GPP Release 19 Network Energy Saving (NES) is expected to introduce dynamic adaptation of RACH occasions (ROs). As such, additional ROs (i.e., the second set) will be provided beyond a baseline RO configuration. This is exemplified in the Fig. 8, wherein a baseline configuration is provided in SIB1 according to legacy means (Fig. 8, top subfigure). Additional ROs are also configured in SIB1 (Fig. 8, mid subfigure) but only intended to be used when indicated by the NW. Bottom subfigure shows the sum of available ROs for the UE where the additional ROs are also activated.

[0245] Fig. 8 schematically illustrates a configuration of legacy (top) first set and additional (middle) second set of random access opportunities (ROs).

[0246] In 3GPP RANI meetings #117 and #119, the following agreements have been made corresponding to PRACH adaptation:

[0247] For adaptation of PRACH in time-domain, support at least the following case(s) - Case 1: no time-domain overlap between the additional PRACH resources for NES-capable UEs and the PRACH resources for legacy UEs

[0248] - Case 2: time-domain overlap but no overlap in frequency domain between the additional PRACH resources for NES-capable UEs and the PRACH resources for legacy UEs

[0249] - Case 3: additional PRACH resources for NES-capable UEs and legacy PRACH resources overlap neither in time nor frequency domains

[0250] - FFS: whether additional conditions are needed to support the above cases - FFS: Additional case whether f u I l / partial overlap in both time and frequency is allowed

[0251] - Above does not preclude discussion for the case where the configuration for additional PRACH resources contains legacy PRACH resourcesTelefonaktiebolaget LM Ericsson (publ) -29- 301-0298WO P112956WO01

[0252] Furthermore, at least msgl-FrequencyStart can be configured separately for the additional PRACH resources at least for 4-step RACH (e.g. as described above for Fig. 6).

[0253] Fig. 9 shows a time-frequency grid of an example configuration, e.g. depicting some problematic situations identified in prior art.

[0254] If there is overlapping between the additional PRACH resources for NES-capable UEs and the PRACH resources for legacy UEs in time domain but no overlap in frequency domain as shown in Fig. 9 above, there could be RA-RNTI ambiguity issue if a legacy UE utilizes legacy RO 0 and NES-capable UE utilizes additional RO 0. This is because when the UE calculates RA-RNTI using the equation in the previous chapter, all parameters for that equation between the legacy UE and NES-capable UE could be same. Then there is contention between legacy UE and NES-capable UE, which may impact the RACH latency of legacy UE since the RACH configuration for said legacy UE may be sparse.

[0255] Independent of, or in extension of, the embodiments disclosed herein, to solve the RA-RNTI ambiguity between the legacy UE and NES-capable UE, the methods 300 and 400 may modify a RA-RNTI equation to discern the RA-RNTI between the legacy UE and NES-capable UE. The methods can have minor impact to different types of RNTI considering the sharing of RNTI values. Some embodiments only apply the modification to a NES-capable UE 100 when the NES-capable UE 100 is performing RACH events.

[0256] For example, the technique may be applied if ("Case 2"):

[0257] - time-domain overlap and

[0258] - no overlap in frequency domain

[0259] between the additional PRACH resources (for NES-capable UEs) and the PRACH resources (for legacy UEs).

[0260] Independent of, or in extension of, the embodiments disclosed herein, the NW 500 (e.g., the network node 200) provides a configuration regarding a first set of RACH resources to the first type of UEs, which are not NES-capable UEs, and a configuration regarding a second set of RACH resources to the second type of UE 100. The second type of UE 100 are NES-capable UE 100. The RA-RNTI equation is modified by adding additional parameters when second type of UE 100 is preparing 302 and 304 for RACH using the second set of RACH resources.Telefonaktiebolaget LM Ericsson (publ) -30- 301-0298WO P112956WO01

[0261] The second type of UEs 100 use the unmodified RA-RNTI equation when using the first set of RACH resources. The second type of UE 100 may still use the unmodified RA-RNTI equation when using the second set of RACH resources and there is no overlapping in frequency domain between the first set of RACH resources and the second set of RACH resources.

[0262] Any embodiment in any aspect may further benefit from including at least one of the features and steps of the following first detailed embodiment.

[0263] Due to current specifications, if there are 2 ROs overlapped in time domain, the RA-RNTI corresponding to these 2 ROs are the same. When UEs search for RAR after having transmitted a PRACH preambles, it is possible that a NES-capable UE decodes a RA-RNTI scrambled PDCCH in Type 1 CSS set successfully although the PDCCH is intended for another UE such as legacy UE, and vice versa. This may confuse UEs, e.g., a UE may detect multiple PDCCH corresponding to its RA-RNTI in the RAR window. In one case, the UE may not find the RAPID, matching its preamble in the wrong RAR resource and recognise a failure in current RACH attempt. However, its own PDCCH schedules a matching RAPID. In another case, the UE finds a matching RAPID addressed by a wrong PDCCH and continues to proceed RAR steps although its RACH attempt has failed already at the first contention of preambles with other UEs.

[0264] To solve the issues above, this IvD proposes modifications to the RA-RNTI determination equation so that legacy UE and NES-capable UE can monitor for appropriate RAR message without confusion.

[0265] We add a parameter to RA-RNTI equation as shown below:

[0266] RA-RNTI= 1 + s_id + 14 x t_id + 14 x 80 x f_id + 14 x 80 x 8 x u l_ca rrierjd + additional parameter

[0267] In one embodiment, when NES-capable UE is preparingfor RACH and calculating RA-RNTI, we add a parameter to the RA-RNTI equation which indicates the provision on additional RACH source. For example, we add the PRACH flag to the equation, where RACH flag = 0 if the RO is a legacy RO, or PRACH flag = 1 if the RO is an additional RACH resource. By this, the RA-RNTI ranges for legacy UEs and NES-capable UEs have no overlap anymore as shown below, no matter their RO are overlapped or not.

[0268] By using flag = 0 for the first set, the equation is not modified for legacy UEs.Telefonaktiebolaget LM Ericsson (publ) - 31 - 301-0298WO P112956WO01

[0269] Below are some examples for the RA-RNTI determination for the first type of UEs which are not NES-capable UEs :

[0270] Minimum value for the first type of UEs

[0271] sjd = 0 , tjd = 0, fjd = 0 , u l_carrier_id=O, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 + 14 x 80 x 8 x 2 x 0 = 1

[0272] Max value for the first type of UEs

[0273] sjd = 13 , tjd = 79, fjd = 7 , ul_carrier_id=l, RA-RNTI= 1 +13 +14 x79 + 14 x80 x7 +14 x 80 x 8 x 1 = 17920

[0274] Alternatively or in addition, any embodiment in any aspect may further benefit from including at least one of the features and steps of the following detailed embodiments.

[0275] Below are some examples for the RA-RNTI determination for monitoring RAR based on additional RACH resources:

[0276] Min value for NES-capable UE

[0277] sjd = 0 , tjd = 0, fjd = 0 , ul_carrierJd=0, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 + 14 x 80 x 8 x 2 x 1 = 17921

[0278] Max value for NES-capable UE

[0279] sjd = 13 , tjd = 79, fjd = 7 , ul_carrierjd=l, RA-RNTI= 1 +13 +14 x79 + 14 x80 x7 +14 x 80 x 8 x 1 + 14 x 80 x 8 x 2 x 1 = 35840

[0280] A UE acquires a configuration regarding a first set of RACH resources, and a configuration regarding a second set of RACH resources. The UE determines that it can transmit PRACH based on a RACH resource that can be selected from the first set of RACH resources and / or the second set of RACH resources. Upon RACH transmission the UE monitors for RAR in a PDCCH search space based on an RA-RNTI. In an embodiment, the UE is a NES-capable UE that can transmit RACH according to first set and / or second set of RACH resources.

[0281] In an embodiment, the RA-RNTI for monitoring RAR based on a first set of RACH resources is determined based on a first set of parameters and a first fixed value. The first set of RACH resources may be legacy RACH resources.

[0282] The first set of parameters may include one or more of

[0283] • the index of the first OFDM symbol of the PRACH occasion

[0284] • the index of the first slot of the PRACH occasion in a system frame

[0285] • the index of the PRACH occasion in the frequency domainTelefonaktiebolaget LM Ericsson (publ) -32- 301-0298WO P112956WO01

[0286] • the UL carrier used for Random Access Preamble transmission (0 for NUL carrier, and 1 for SUL carrier)

[0287] The first fixed value may be 1.

[0288] In an embodiment, the RA-RNTI for monitoring RAR based on additional RACH resources is determined based on the first set of parameters and a second value. In an embodiment, the second value is a second fixed value, and the second fixed value is distinct from the first fixed value.

[0289] In an embodiment, the second fixed value is the sum of the first fixed value and a second constant value.

[0290] In an embodiment, the second constant value may be given by the maximum value of the RA-RNTI allowed for monitoring RAR based on the first set of RACH resources. The second set of RACH resources may be additional RACH resources.

[0291] In above examples, the range of RNTI values used for monitoring RAR according to RACH in first set of RACH resources may be distinct from the range of RNTI values used for monitoring RAR according to RACH based on the second set of RACH resources.

[0292] In an embodiment, the second value is indicated via higher layer signaling. The second value may be distinct from the PRACH configuration index of the second set of RACH resources.

[0293] In an embodiment, a reference index of the PRACH occasion in the frequency domain used to determine RA-RNTI for PRACH according to RACH based on the second set of RACH resources is based on the index of the PRACH occasion in the frequency domain according to the second set of RACH resource and a parameter related to the number of PRACH occasions in the frequency domain based on the first set of RACH resources.

[0294] In another embodiment, the reference index of the PRACH occasion in the frequency domain used to determine RA-RNTI for PRACH according to RACH based on the second set of RACH resources is based on a) the index of the PRACH occasion in the frequency domain according to the second set of RACH resource and b) a parameter related to the number of PRACH occasions in the frequency domain based on the first set of RACH resources and at least a modulo operator.

[0295] In another embodiment, the reference index of the PRACH occasion in the frequency domain used to determine RA-RNTI for PRACH according to RACH based on the second set of RACH resources is based on a sum of a) the index of the PRACH occasion in the frequency domain according to the second set of RACH resource and b) a parameter related to the number of PRACH occasions in the frequency domain based on the first set of RACH resources and a modulo operation. The modulo operation may be an operation that is used to map the resulting sum into theTelefonaktiebolaget LM Ericsson (publ) -33- 301-0298WO P112956WO01

[0296] existing range of "index of the PRACH occasion in the frequency domain used to determine RA-RNTI".

[0297] For example,

[0298] • The fjd for determining RA-RNTI for RACH according to the second set of RACH resources (fjd-second-set) may be based on

[0299] o the index of the PRACH occasion in the frequency domain according to the second set of RACH resource (b0) and o a parameter related to the number of PRACH occasions in the frequency domain based on the first set of RACH resources (a0).

[0300] • In a sub-example,

[0301] o the parameter related to the number of PRACH occasions in the frequency domain based on the first set of RACH resources (a0) may be the maximum value of the index of the PRACH occasion in the frequency domain according to the first set of RACH resource (i.e. maximum value of fjd used for determining RA-RNTI for RACH based on the first set).

[0302] • In a sub-example,

[0303] o fjd-second-set = modulo(b0+a0, N), where N may a reference number, where modulo function denotes. In an example, N = 8. Using the above examples, in case of overlapping ROs between first and second set of RACH resources, the ambiguity in RA-RNTI is resolved by using a reference RO-index that is utilized for determining the RA-RNTI for RACH according to second set of RACH resources. In an example, a modulo function is used to wrap around the reference RO-index into the existing range of RO-index values for RA-RNTI determination. This ensures that the RNTI space is utilized efficiently without having to budget more RNTIs for RA-RNTI when second set of RACH resources are introduced in the system.

[0304] In anotherembodiment, we add a parameter which indicates the expanded RA-RNTI value (positive or negative values). For example, the value could be a fix positive or negative value for all conditions. By this, the RA-RNTI ranges for legacy U Esand NES-capable UEs are different as shown below, when their ROs are overlapped in time domain.

[0305] RA-RNTI for legacy UE

[0306] sjd = 0 , tjd = 0, fjd = 0 , ul_carrierJd=O, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 = 1

[0307] RA-RNTI for NES-capable UETelefonaktiebolaget LM Ericsson (publ) -34- 301-0298WO P112956WO01

[0308] sjd = 0 , tjd = 0, fjd = 0 , ul_carrier_id=O, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 +10= 11

[0309] In yet another embodiment, we add a parameter which is a variant. For example, a negative value if the RA-RNTI after modification exceeds the range for original RA-RNTI, otherwise keep the additional parameters positive, as shown below.

[0310] RA-RNTI for the first type of UEs sjd = 13 , tjd = 79, fjd = 7 , ul_carrier_id=l, RA-RNTI= 1 +13 +14 X79 + 14 x80 x7 +14 x 80 x 8 x 1 = 17920

[0311] RA-RNTI for NES-capable UE

[0312] sjd = 13 , tjd = 79, fjd = 7 , ul_carrier_id=l, RA-RNTI= 1 +13 +14 x79 + 14 x80 x7 +14 x 80 x 8 x 1 - 1= 17919

[0313] or

[0314] RA-RNTI for the first type of UEs

[0315] sjd = 0 , tjd = 0, fjd = 0 , ul_carrierJd=0, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 = 1

[0316] RA-RNTI for NES-capable UE

[0317] sjd = 0 , tjd = 0, fjd = 0 , ul_carrierJd=0, RA-RNTI= 1 + 0 + 14 x 0 + 14 x 80 x 0 + 14 x 80 x 8 x 0 +1= 2

[0318] Regarding when to apply this modification:

[0319] In one embodiment, NES-capable UEs applies this only when the NES-capable UE is using the second set of RACH resource to transmit a PRACH and monitors for RAR. Because if NES-capable UE use modified equation to the first set of RO, NW confuses that which RA-RNTI it should use to scramble PDCCH for RAR. So, this modification is only applied when additional RO is used for NES-capable UEs.

[0320] In another embodiment, the modified equation is applied when there is overlapping between the first set and the second set of RACH resource in time domain.

[0321] In yet another embodiment, the modified equation is applied regardless if there is overlapping between the first set and the second set RACH resource in time domain.

[0322] Herein, RA-RNTI may refer to Random Access Radio Network Temporary Identifier or any other RA identifier. Random Access Response is abbreviated by RAR.

[0323] The abbreviations RACH for Random Access Channel and PRACH for Physical Random-Access Channel may be interchanged. The UE for User Equipment is an example of the radio device. The second set of ROs may relate to any aspect ofTelefonaktiebolaget LM Ericsson (publ) -35- 301-0298WO P112956WO01

[0324] NES, i.e. Network Energy Saving. The abbreviation RO used equally for RA occasion and RACH occasion.

[0325] Alternatively or in addition to the listed embodiments and the above detailed embodiments, any aspect may further apply any one of the following steps, features, and definitions.

[0326] Herein, the words "index", "identifier", and "id" may be interpreted as synonymous. For example, the expressions may be interchanged or combined. For example, the RA-RNTI may be referred to as an identifier. The RA-RNTI may be a function of multiple indices. The indices may be abbreviated by "id".

[0327] Hereinbelow, the numerical values are given as concrete examples, and not for limiting the invention. For example, any one of the numerical values 14, 80, 8, and 2 for range sizes of indices can be changed by the skilled person as needed.

[0328] First embodiment

[0329] The RA-RNTI may be distinguished for the first set of random-access occasions (ROs) and the second set of ROs by an offset, e.g. an offset of the least significant index in a joint index for the RA-RNTI.

[0330] Alternatively or in addition,

[0331] RA-RNTI = 1 + sjd + 14 x tjd + 14 x 80 x f_id + 14 x 80 x 8 x u l_carrier_id

[0332] + additional parameter

[0333] or

[0334] RA-RNTI = s_id + 14 x [t_id + 80 x (f_id + 8 x ul_carrier_id)] + constant

[0335] wherein the constant equals additional parameter+1.

[0336] For example, the additional parameter may be zero for the first set of randomaccess occasions (ROs). The additional parameter may be a non-zero offset for the second set of ROs.

[0337] At least some variants of the first embodiments may ensure that the value of the RA-RNTI is unique, i.e. the set of values for the RA-RNTI for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.Telefonaktiebolaget LM Ericsson (publ) -36 - 301-0298WO P112956WO01

[0338] Furthermore, by setting the additional parameter to zero for the first set of ROs, the technique may be backward compatible to radio device capable of perform random access only in ROs the first set of ROs (e.g., non-NES ROs).

[0339] In a variant of any embodiment, the second set of ROs may be the set of NES ROs for network energy saving (NES).

[0340] Second embodiment

[0341] The RA-RNTI may comprise a further index (e.g., a flag) that is indicative of whether or not the RO is in the first set of ROs or in the second set of ROs.

[0342] By way of example:

[0343] RA-RNTI = 1 + sjd + 14 x [t_id + 80 x (f_id + 8 x (ul_carrier_id + 2 x flag))] e.g., wherein the flag is zero for the first set of ROs and one for the second set of ROs.

[0344] Alternatively or in addition, the flag may be indicative of whether or not (e.g., 0 for false, 1 for true) the RO is a NES RO. The flag may be referred to as NESJlag.

[0345] Since the flag is the most significant index in the joint index defining the RA-RNTI, at least some variants of the second embodiments may ensure that the value of the RA-RNTI is unique, i.e. the set of values for the RA-RNTI for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0346] Second embodiment as an example of the first embodiment

[0347] RA-RNTI = 1 + sjd + 14 x [tjd + 80 x (f_id + 8 x ul_carrier_id)]

[0348] f 0, for NESJlag = 0 or non-NES RO

[0349] +lNnon-NES, for NESJlag = 1 or NES RO

[0350] or

[0351] RA-RNTI = sjd + 14 x [tjd + 80 x (f_id + 8 x ul_carrierjd)]

[0352] f 1, for NESJlag = 0 or non-NES RO

[0353] +lNnon-NES+ 1, for NESJlag = 1 or NES RO

[0354] wherein the constant equals Nnon-NES+ 1 = 14 x 80 x 8 x 2 + 1 = 17921.

[0355] Third embodiment

[0356] The RA-RNTI for the first set of ROs may differ from the RA-RNTI for the second set of ROs by an offset, e.g. an offset of one index in a joint index for the RA-RNTI.Telefonaktiebolaget LM Ericsson (publ) -37 - 301-0298WO P112956WO01

[0357] The one index in the joint index may be a sub-significant index (e.g., an index other than the most significant index. Moreover, the one index may or may not be the least significant index. Alternatively or in addition, the one index may be an index for the frequency domain of the RO, e.g., an index indicative of a location in the frequency domain for the RO. Therefore, the RA identifier for the first set of ROs may differ from the RA identifier for the second set of ROs by a difference in the index of the frequency domain of the ROs. The index of the frequency domain of the second set of ROs may include an offset compared to the index of the frequency domain of the first set of ROs.

[0358] By way of example,

[0359] RA-RNTI = 1 + sjd + 14 x [tjd + 80 x (f_first_set_id + 8 x ul_carrier_id)]

[0360] for the first set of ROs

[0361] and

[0362] RA-RNTI = 1 + s_id + 14 x [t_id + 80 x (f_second_set_id+f_number_in_first_set + 8 x ul_carrier_id)]

[0363] for the second set of ROs.

[0364] Herein, the index f_id for the frequency domain for a RO in the first set of ROs (e.g., the non-NES ROs) may be referred to as f_first_set_id. Alternatively or in addition, the index f_id for the frequency domain for a RO in the second set of ROs (e.g., the NES ROs) may be referred to as f_second_set_id.

[0365] The one index for the frequency domain may be limited. For example, a range of the one frequency domain index within the joint index for the RA-RNTI may be disjoint for the first set and the second set of ROs.

[0366] Optionally,

[0367] 0 <= f_first_set_id < f_number_in_first_set

[0368] and

[0369] 0 <= f_second_set_id+f_number_in_first_set < 8.

[0370] This option of the third embodiment can ensure that the value of the RA-RNTI is unique, i.e. the set of values for the RA-RNTI for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.Telefonaktiebolaget LM Ericsson (publ) -38- 301-0298WO P112956WO01

[0371] Third embodiment as an example of the first embodiment

[0372] The RA-RNTI may be distinguished for the first set of ROs and the second set of ROs by an offset, e.g. an offset of the least significant index in a joint index for the RA-RNTI.

[0373] For example,

[0374] RA-RNTI = 1 + sjd + 14 x [tjd + 80 x (f_id + 8 x ul_carrier_id)]

[0375] first_offset, for the first set of ROs

[0376]

[0377] second_offset, for the second set of ROs

[0378] e.g., wherein first_offset = 0 and second_offset = 14 x 80 x f_number_in_first_set.

[0379] By way of example, f_number_in_first_set = f_Nnon-NES, that is the (e.g., maximum) number of locations in the frequency domain for the non-NES ROs.

[0380] For f_ id = f_second_set_id (e.g., for a RO in the second set of ROs):

[0381] RA-RNTI = 1 + s_id + 14 x [t_id + 80 x (f_second_set_id + 8 x ul_carrier_id)] + 14 x 80 x f_number_in_first_set

[0382] or

[0383] RA-RNTI = s_id + 14 x [t_id + 80 x (f_set_id + 8 x ul_carrier_id)]

[0384] + constant

[0385] wherein constant = 1+14 x 80 x f_number_in_first_set.

[0386] In any embodiment, the RA-RNTI may be a joint index of indices that define a RO.Telefonaktiebolaget LM Ericsson (publ) -39- 301-0298WO P112956WO01

[0387] Definition: Joint index

[0388] A function RA-RNTI = RA-RNTI(idi, ...) is referred to as "joint index", if the function may be represented or approximated by

[0389] RA-RNTI = idi + rangejdi x (

[0390] id? + rangejdz x (

[0391] ids + rangejds x (

[0392] id4 + optionally further indices

[0393] )

[0394] )

[0395] )

[0396] + constant

[0397] The joint index is a function of the indices idn(for n = 1,

[0398]

[0399] which are also referred to as the indices "within the joint index". The indices

[0400] idn(for n = 1, ...)

[0401] within the joint index may be variables of the joint index. The range sizes range_idn(for n = 1, ...)

[0402] may be parameters of the joint index.

[0403] Equivalently, the joint index may be recursively defined, e.g. by applying the replacement at least once:

[0404] RA-RNTI = idi + constant

[0405] Replacement: "

[0406]

[0407] " " "

[0408] The RA-RNTI may be a joint index of at least one of:

[0409] - an index s_id of a first OFDM symbol of the RO;

[0410] - an index t_id of a time domain of the RO, optionally an index of a temporal radio resource of the RO, a slot of the RO, a subframe of the RO, or a radio frame of the RO;

[0411] - an index f_id of a frequency domain of the RO, optionally of a subcarrier of the RO or a radio block of the RO; and

[0412] - an index u l_ca rrierjd of an uplink carrier of the RO.Telefonaktiebolaget LM Ericsson (publ) -40- 301-0298WO P112956WO01

[0413] Definition: Cyclic index

[0414] Any (e.g., one or each) index idnof the indices within the joint index may be cyclic within its range 0 < idn< range_idn(e.g., for each n = 1, That is, the joint index may be the function RA-RNTI = RA-RNTI(idi mod rangejdi, ...) with the modulo operation applied to any (e.g., one or each) index idnwithin the joint index.

[0415] Definition: Most significant index, sub-significant index

[0416] The first-mentioned index within the joint index is referred to as the least significant index. The last-mentioned index within the joint index is referred to as the most significant index. Within the joint index, any index that is not the most significant index is referred to as sub-significant index.

[0417] Definition: Limited index

[0418] Any index idnof the indices within the joint index may be limited to its range 0 < idn< range_idn(e.g., for each n = 1, ...).

[0419] Alternatively or in addition, an index within the joint index for the RA-RNTI may be limited to a first frequency range and a second frequency range for the first set of ROs and the second set of ROs, respectively. E.g., the first frequency range and the second frequency range may be subsets within a full frequency range

[0420] 0 <f_id < range_f_id of the index f_id for the frequency domain.

[0421] In a variant of any embodiment, one index within the RA-RNTI may be offset and / or a modulo operator may be applied to the index within the RA-RNTI. This can reduce the probability of a collision less without limiting the index within the RA-RNTI.

[0422] An index (e.g., f_id) within the RA-RNTI as a joint index may be offset for the second set of ROs relative to the same index within the RA-RNTI used for the first set of ROs. For example:

[0423] RA-RNTI = RA-RNTI (sjd, tjd, fjd, ul_carrier_id)

[0424] for the first set of ROs

[0425] and

[0426] RA-RNTI = RA-RNTI (s_id, t_id, f_id + f_offset, ul_carrier_id)

[0427] for the second set of ROs.Telefonaktiebolaget LM Ericsson (publ) -41- 301-0298WO P112956WO01

[0428] The f_offset may be equal to the number of locations in the frequency domain for ROs in the first set of ROs (f_number_in_first_set).

[0429] Alternatively or in addition, for the second set of ROs:

[0430] RA-RNTI = 1 + s_id + 14 x [t_id + 80 x (modulo (f_id+f_number_in_first_set, 8) + 8 x ul_carrier_id)]

[0431] Optionally, f_id is an index of the frequency domain for the second set of ROs (e.g., f_id = f_second_set_id for the frequency domain for the second set of ROs).

[0432] For example, for a NES-set of ROs, i.e., for the second set of NES ROs:

[0433] RA-RNTI = 1 + sjd + 14 x [tjd + 80 x (modulo (f_idNES+Nnon-NES, 8)

[0434] + 8 x ul_carrier_id)]

[0435] wherein Nnon-NESis the (e.g., maximum) number of locations in the frequency domain for non-NES ROs.

[0436] Fig. 10 shows a schematic block diagram for an embodiment of the device 100. The device 100 comprises processing circuitry, e.g., one or more processors 1004 for performing the method 300 and memory 1006 coupled to the processors 1004. For example, the memory 1006 may be encoded with instructions that implement at least one of the modules 102, 104, and 106.

[0437] The one or more processors 1004 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and / or encoded logic operable to provide, either alone or in conjunction with other components of the device 100, such as the memory 1006, radio access or radio device functionality. For example, the one or more processors 1004 may execute instructions stored in the memory 1006. Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein. The expression "the device being operative to perform an action" may denote the device 100 being configured to perform the action.

[0438] As schematically illustrated in Fig. 10, the device 100 may be embodied by a radio device 1000, e.g., functioning as a UE. The radio device 1000 comprises a radioTelefonaktiebolaget LM Ericsson (publ) -42- 301-0298WO P112956WO01

[0439] interface 1002 coupled to the device 100 for radio communication with one or more network nodes, e.g., functioning as a RAP receiving base station or gNB.

[0440] Fig. 11 shows a schematic block diagram for an embodiment of the device 200. The device 200 comprises processing circuitry, e.g., one or more processors 1104 for performing the method 400 and memory 1106 coupled to the processors 1104. For example, the memory 1106 may be encoded with instructions that implement at least one of the modules 201, 204, 205, and 206.

[0441] The one or more processors 1104 may be a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, microcode and / or encoded logic operable to provide, either alone or in conjunction with other components of the device 200, such as the memory 1106, random access receiver or network node functionality. For example, the one or more processors 1104 may execute instructions stored in the memory 1106. Such functionality may include providing various features and steps discussed herein, including any of the benefits disclosed herein. The expression "the device being operative to perform an action" may denote the device 200 being configured to perform the action.

[0442] As schematically illustrated in Fig. 11, the device 200 may be embodied by a network node 1100, e.g., functioning as a gNB. The network node 1100 comprises a radio interface 1102 coupled to the device 200 for radio communication with one or more radio devices, e.g., functioning as a UEs.

[0443] With reference to Fig. 12, in accordance with an embodiment, a communication system 1200 includes a telecommunication network 1210, such as a 3GPP-type cellular network, which comprises an access network 1211, such as a radio access network, and a core network 1214. The access network 1211 comprises a plurality of base stations 1212a, 1212b, 1212c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 1213a, 1213b, 1213c. Each base station 1212a, 1212b, 1212c is connectable to the core network 1214 over a wired or wireless connection 1215. A first user equipment (UE) 1291 located in coverage area 1213c is configured to wirelessly connect to, or be paged by, the corresponding base station 1212c. A second UE 1292 in coverage area 1213a is wirelessly connectable to the corresponding base station 1212a. While aTelefonaktiebolaget LM Ericsson (publ) -43- 301-0298WO P112956WO01

[0444] plurality of UEs 1291, 1292 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 1212.

[0445] Any of the base stations 1212 may embody the network node 200, 1100; and the UEs 1291, 1292 may embody the radio device 100, 1000.

[0446] The telecommunication network 1210 is itself connected to a host computer 1230, which may be embodied in the hardware and / or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 1230 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 1221, 1222 between the telecommunication network 1210 and the host computer 1230 may extend directly from the core network 1214 to the host computer 1230 or may go via an optional intermediate network 1220. The intermediate network 1220 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 1220, if any, may be a backbone network or the Internet; in particular, the intermediate network 1220 may comprise two or more sub-networks (not shown).

[0447] The communication system 1200 of Fig. 12 as a whole enables connectivity between one of the connected UEs 1291, 1292 and the host computer 1230. The connectivity may be described as an over-the-top (OTT) connection 1250. The host computer 1230 and the connected UEs 1291, 1292 are configured to communicate data and / or signaling via the OTT connection 1250, using the access network 1211, the core network 1214, any intermediate network 1220 and possible further infrastructure (not shown) as intermediaries. The OTT connection 1250 may be transparent in the sense that the participating communication devices through which the OTT connection 1250 passes are unaware of routing of uplink and downlink communications. For example, a base station 1212 need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 1230 to be forwarded (e.g., handed over) to a connected UE 1291. Similarly, the base station 1212 need not be aware of the future routing of an outgoing uplink communication originating from the UE 1291 towards the host computer 1230.Telefonaktiebolaget LM Ericsson (publ) -44- 301-0298WO P112956WO01

[0448] By virtue of the method 300 being performed by any one of the UEs 1291 or 1292 and / or the method 400 by any one of the base stations 1212, the performance or range of the OTT connection 1250 can be improved, e.g., in terms of increased throughput and / or reduced latency. More specifically, the host computer 1230 may indicate to the RAN 500 or the network node 200 or the radio device 100 (e.g., on an application layer) the need to perform the random access.

[0449] As has become apparent from above description, at least some embodiments of the technique avoid the RA-RNTI ambiguity issue between the first type of UEs and NES-capable UEs when there is overlapping between the first set of RACH resources and the second set of RACH resources. This ensures the impact to RACH latency of the first type of UEs is minimized when RACH adaptation is applied, because it alleviates the contention between UEs in CBRA.

[0450] The technique may, alternatively in addition to any aspect, comprise the following embodiments.

[0451] Embodiment 1. A method (300) performed by a radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the method (300) comprising:

[0452] determining (302) a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;

[0453] transmitting (304), to the network node (200), a RA preamble, RAP, using the RO; and

[0454] receiving (306), from the network node (200), a RA response, RAR, using the RA identifier.

[0455] The RAR may be received in response to the RAP.

[0456] The RA occasions (ROs) may also be referred to as random-access opportunities.

[0457] The determined RA identifier may be different for different ROs. E.g., different RA identifiers may be determined for ROs that overlap in the time domain and / or that do not overlap in the frequency domain.Telefonaktiebolaget LM Ericsson (publ) - 45 - 301-0298WO P112956WO01

[0458] Herein, time domain or frequency domain may refer to temporal and frequency radio resources, respectively, of the RAN or used by the network node of the RAN.

[0459] The RAP may be referred to as a first message, e.g., of a random access procedure. The RAR may may be referred to as a second message, e.g., of a random access procedure. The random access procedure may comprise 2 steps or 4 steps.

[0460] The radio device may use the RA identifier to search for downlink control information (DCI, e.g. on a physical downlink control channel, PDCCH) in a second message (from the network node and / or in response to the RAP). Alternatively or in addition, the radio device may use the RA identifier to receiver the RAR, wherein a cyclic redundancy check (CRC) for the RAR (e.g., for the DCI scheduling the RAR) is scrambled with the RA identifier.

[0461] Any RO may also be referred to as random access channel (RACH) occasion or RACH resource or random-access resources (RA resources).

[0462] The first set of ROs may be different, e.g. disjoint, from the second set of ROs. The ROs may be radio resources in a combination of time (or temporal resources) and frequency (or frequency resources) of the network node, e.g. in a time-frequency grid of the network node.

[0463] Embodiment 2. The method (300) of embodiment 1, wherein different RA identifiers are determined (302) for ROs that are equal or overlap in the time domain; and / or

[0464] wherein the determined (302) RA identifier is dependent on a frequency domain of the RO; and / or

[0465] wherein different RA identifiers are determined (302) for ROs that are different, optionally offset, in the frequency domain; and / or

[0466] wherein a RA identifier determined (302) for a RO from the first set is different from a RA identifier determined (302) for a RO from the second set.

[0467] Embodiment 3. The method (300) of embodiment 1 or 2, wherein receiving (306) the RAR comprises searching within a RAR window using the RA identifier.

[0468] The RAR window may be defined according to 3GPP TS 38.213, version 18.5.0 or later (e.g., Release 19), clause 8.2.Telefonaktiebolaget LM Ericsson (publ) -46- 301-0298WO P112956WO01

[0469] Embodiment 4. The method (300) of any one of embodiments 1 to 3, wherein the first set of ROs are semi-statically configured by the network node (200), optionally using a system information block 1, SI Bl, for RA; and / or

[0470] wherein the second set of ROs comprises ROs associated with network energy saving, NES, operations of the network node (200) or the RAN (500).

[0471] By distinguishing between legacy ROs and those intended for NES operations, the two sets of ROs enable the radio device to correctly derive and use the appropriate RA identifier for either set of ROs, e.g. avoiding contention and ambiguity when both sets of occasions exist simultaneously.

[0472] The first set of ROs may be referred to as legacy set or the ROs in the first set may be referred to as legacy ROs. Alternatively or in addition, the second set of ROs may be referred to as NES set or the ROs in the second set may be referred to as NES ROs.

[0473] The radio device may be referred to as enhanced or capable (e.g., NES-capable) radio device, e.g. because the radio device is capable of performing RA using one or more ROs (e.g., NES ROs) of the second set (e.g., NES set).

[0474] By ensuring that the NES-capable radio device can utilize two sets of RO — e.g., one for legacy or baseline operation and one for NES-based operation (or adaptation) —with distinct RA identifiers (e.g., radio network temporary identifiers), the radio device avoids collisions or ambiguity in the RAR or in receiving the RAR. Alternatively or in addition, the RAR may be uniquely associated with the radio device, e.g. even if another radio device performs RA on a RO that overlaps in the time domain with the RO used by the radio device. This enables more flexible random-access adaptation while preventing ambiguity of the RA identifier between NES ROs or between a NES RO and a legacy RO, and thereby improves random-access efficiency.

[0475] Embodiment 5. The method (300) of any one of embodiments 1 to 4, wherein the RO used for the transmission (304) of the RAP is from the second set of ROs; and / or

[0476] wherein the RO used for the transmission (304) of the RAP is a NES RO for NES operation of the network node (200).

[0477] Embodiment 6. The method (300) of any one of embodiments 1 to 5, wherein the RA identifier is a RA radio network temporary identifier, RA-RNTI.Telefonaktiebolaget LM Ericsson (publ) -47 - 301-0298WO P112956WO01

[0478] Any RA identifier may be a RA-RNTI.

[0479] Herein, the words "index", "identifier", and "id" may be interpreted as synonymous. For example, the expressions may be interchanged or combined. For example, the RA-RNTI may be referred to as an identifier. The RA-RNTI may be a function of multiple indices. The indices may be abbreviated by "id" or other names including "id".

[0480] Embodiment 7. The method (300) of any one of embodiments 1 to 6, further comprising:

[0481] Acquiring (301), from the network node (200), the first set of ROs and / or the second set of ROs.

[0482] The acquiring may comprise receiving one or more configuration messages indicative of the first set of ROs and / or the second set of ROs.

[0483] Embodiment 8. The method (300) of any one of embodiments 1 to 7, wherein the radio device (100) determines (302) the RA identifier being dependent on the first set and the second set, optionally being different for the first set and the second set, only if the RO is from the second set of ROs and overlaps in the time domain with a ROs from the first set of ROs.

[0484] Restricting the identifier distinction to periods of time overlap can avoid unnecessary reconfiguration of the RA identifier space during non-overlapping operation, minimizing complexity and conserving resources while still preventing RA identifier ambiguity or collisions during overlapping resources.

[0485] Embodiment 9. The method of any one of embodiments 1 to 8, wherein the determining (302) comprises adding a non-zero additional parameter to a baseline RA identifier if the RO is from the second set of ROs, optionally wherein the baseline RA identifier is determined (302) as the RA identifier if the RO is from the first set of ROs and / or wherein the baseline RA identifier is independent of whether the RO is in the first set or in the second set of ROs.

[0486] By adding the additional parameter (e.g., an offset or a NES-flag multiplied by a factor) to the baseline RA identifier (e.g., to a formula for computing the baseline RA identifier), e.g. only for ROs in the second set (e.g., the NES set of ROs), an embodiment of the method can ensure that the determined RA identifier for the (or for any) RO in the second set does not overlap with the baseline RA identifier determined for a simultaneous RO in the first set orTelefonaktiebolaget LM Ericsson (publ) -48- 301-0298WO P112956WO01

[0487] for any RO in the first set. Same or further embodiments can eliminate an ambiguity in searching for random-access responses (RARs) based on the RA identifier.

[0488] Embodiment 10. The method of any one of embodiments 1 to 9, wherein the additional parameter is a fixed offset, optionally configured by the network node (200) and / or to determine (302) an expanded range of RA identifiers for the second set.

[0489] The additional parameter may be a fixed offset signaled in advance by the network node.

[0490] Using a fixed offset (e.g., signaled by the network node) can permit a consistent shift of the RA identifier space for the second set relative to ROs determined for the first set. This can reduce signaling overhead per RA event and optimizes radio resource usage by maintaining clarity and unambiguity of the RAR.

[0491] Hereinbelow, the numerical values are given as concrete examples, and not for limiting the invention. For example, any one of the numerical values range_s_id = 14, range_t_id = 80, range_f_id = 8, and range_ul_carrier_id = 2 for range sizes of indices can be changed by the skilled person as needed.

[0492] Embodiment 11. The method of any one of embodiments 1 to 10, wherein the determined (302) RA identifier is distinguished for the first set of ROs and the second set of ROs by an offset, optionally an offset of the least significant index in a joint index for the RA identifier.

[0493] Embodiment 12. The method of any one of embodiments 1 to 11, wherein RA identifier = 1 + s_id + range_s_id x t_id + range_s_id x range_t_id x f_id +

[0494] range_s_id x range_t_id x range_f_id x ul_carrier_id

[0495] + additional parameter.

[0496] Alternatively or in addition,

[0497] RA identifier = s_id + range_s_id x [t_id + range_t_id x (f_id + range_f_id x

[0498] u l_carrier_id)] + constant

[0499] wherein the constant equals additional parameter+1.Telefonaktiebolaget LM Ericsson (publ) -49 - 301-0298WO P112956WO01

[0500] 13. The method of any one of embodiments 1 to 12, wherein the additional parameter is zero for the first set of ROs; and / or

[0501] wherein the additional parameter is a non-zero offset for the second set of ROs.

[0502] At least some variants of the first embodiments may ensure that the value of the RA identifier may be unique, i.e. the set of values for the RA identifier for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0503] Furthermore, by setting the additional parameter to zero for the first set of ROs, the technique may be backward compatible to radio device capable of perform random access only in ROs the first set of ROs (e.g., non-NES ROs).

[0504] In a variant of any embodiment, the second set of ROs may be the set of NES ROs for network energy saving (NES).

[0505] Embodiment 14. The method of any one of embodiments 1 to 13, wherein the RA identifier comprises an index, optionally a flag, that is indicative of whether or not the RO is in the first set of ROs or in the second set of ROs.

[0506] Embodiment 15. The method of any one of embodiments 1 to 14, wherein RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_id + range_f_id x (ul_carrier_id + range_ul_carrier_id x flag))]

[0507] optionally wherein the flag is zero for the first set of ROs and one for the second set of ROs.

[0508] Alternatively or in addition, the flag may be indicative of whether or not (e.g., 0 for false, 1 for true) the RO is a NES RO. The flag may be referred to as NESJlag.

[0509] Since the flag is the most significant index in the joint index defining the RA identifier, at least some variants of the embodiments may ensure that the value of the RA identifier is unique, i.e. the set of values for the RA identifier for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0510] Embodiment 16. The method of any one of embodiments 1 to 15, wherein RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_id + range_f_id x , . . f 0, for the first set

[0511] ul carrier id + hT f, .

[0512] - ~ (Nnon-NES, for the second set

[0513] orTelefonaktiebolaget LM Ericsson (publ) -50- 301-0298WO P112956WO01

[0514] RA identifier = s_id + range_s_id x [t_id + range_t_id x (f_id + range_f_id x

[0515] , . . f 1, for the first set

[0516] ul carrier id)] +KT.4 f, .

[0517] - ~ (Nnon-NES+ 1, for the second set

[0518] optionally wherein the constant equals Nnon-NES+ 1 = range_s_id x range_t_id x range_f_id x range_ul_carrier_id + 1 or 17921.

[0519] Embodiment 17. The method of any one of embodiments 1 to 16, wherein RA identifier is distinguished for the first set of ROs and the second set of ROs by an offset of one index in a joint index for the RA identifier.

[0520] The one index in the joint index may be a sub-significant index (e.g., an index other than the most significant index. Moreover, the one index may or may not be the least significant index. Alternatively or in addition, the one index may be an index for the frequency domain of the RO, e.g., an index indicative of a location in the frequency domain for the RO.

[0521] Embodiment 18. The method of any one of embodiments 1 to 17, wherein RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_first_set_id

[0522] + range_f_id x ul_carrier_id)]

[0523] for the first set of ROs

[0524] and

[0525] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_second_set_id+f_number_in_first_set + range_f_id x ul_carrier_id)] for the second set of ROs.

[0526] Herein, the index f_id for the frequency domain for a RO in the first set of ROs (e.g., the non-NES ROs) may be referred to as f_first_set_id. Alternatively or in addition, the index f_id for the frequency domain for a RO in the second set of ROs (e.g., the NES ROs) may be referred to as f_second_set_id.

[0527] The one index for the frequency domain may be limited. For example, a range of the one frequency domain index within the joint index for the RA identifier may be disjoint for the first set and the second set of ROs.

[0528] Embodiment 19. The method of embodiment 18, wherein

[0529] 0 <= f_first_set_id < f_number_in_first_set

[0530] andTelefonaktiebolaget LM Ericsson (publ) -51- 301-0298WO P112956WO01

[0531] 0 <= f_second_set_id+f_number_in_first_set < range_f_id.

[0532] This option of the embodiment can ensure that the value of the RA identifier is unique, i.e. the set of values for the RA identifier for the first set of ROs (e.g., the non-NES ROs) and for the second set of ROs (e.g., the NES ROs) is disjoint.

[0533] Embodiment 20. The method of any one of embodiments 1 to 19, wherein the RA identifier may be distinguished for the first set of ROs and the second set of ROs by an offset of the least significant index in a joint index for the RA identifier.

[0534] Embodiment 21. The method of any one of embodiments 1 to 20, wherein RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_id

[0535] + range_f_id x ul_carrier_id)]

[0536] f first_offset, for the first set of ROs

[0537] (second_offset, for the second set of ROs

[0538] optionally wherein first_offset = 0 and second_offset = range_s_id x range_t_id x f_number_in_first_set.

[0539] By way of example, f_number_in_first_set = f_Nnon-NES, that is the (e.g., maximum) number of locations in the frequency domain for the non-NES ROs.

[0540] For f_ id = f_second_set_id (e.g., for a RO in the second set of ROs):

[0541] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_second_set_id

[0542] + range_f_id x ul_carrier_id)]

[0543] + range_s_id x range_t_id x f_number_in_first_set

[0544] or

[0545] RA identifier = s_id + range_s_id x [t_id + range_t_id x (f_set_id

[0546] + range_f_id x ul_carrier_id)]

[0547] + constant

[0548] wherein constant = l+range_s_id x range_t_id x f_number_in_first_set.

[0549] Embodiment 22. The method of any one of embodiments 1 to 21, wherein the determined (302) RA identifier is a joint index of indices that define the RO.Telefonaktiebolaget LM Ericsson (publ) -52- 301-0298WO P112956WO01

[0550] Embodiment 23. The method of embodiment 22, wherein the joint index is a function RA identifier = RA identif ier(id i, ...) that is represented or representable or approximated by

[0551] RA identifier = id i + rangejdi x (

[0552] id? + rangejdz x (

[0553] ids + rangejds x (

[0554] id4 + optionally further indices

[0555] )

[0556] )

[0557] )

[0558] + constant.

[0559] The joint index may be a function of the indices idn(for n = 1,

[0560]

[0561] which are also referred to as the indices "within the joint index". The indices

[0562] idn(for n = 1, ...)

[0563] within the joint index may be variables of the joint index. The range sizes range_idn(for n = 1, ...)

[0564] may be parameters of the joint index.

[0565] Alternatively or in addition, the joint index may be recursively defined, e.g. by applying the replacement at least once:

[0566] RA identifier = id i + constant

[0567] Replacement: "

[0568]

[0569] " " "

[0570] Embodiment 24. The method of any one of embodiments 1 to 23, wherein the RA identifier is a joint index of at least one of:

[0571] - an index s_id of a first OFDM symbol of the RO;

[0572] - an index t_id of a time domain of the RO, optionally an index of a temporal radio resource of the RO, a slot of the RO, a subframe of the RO, or a radio frame of the RO;

[0573] - an index f_id of a frequency domain of the RO, optionally of a subcarrier of the RO or a radio block of the RO; and

[0574] - an index u l_ca rrierjd of an uplink carrier of the RO, optionally of a non- supplementary uplink carrier, NUL carrier, or a supplementary uplink carrier, SUL carrier.Telefonaktiebolaget LM Ericsson (publ) -53 - 301-0298WO P112956WO01

[0575] Embodiment 25. The method of any one of embodiments 1 to 24, wherein one or each index idnof the indices within the RA identifier is cyclic within its range 0 < idn< range_idnfor n = 1, ... .

[0576] Embodiment 26. The method of any one of embodiments 1 to 25, wherein the RA identifier is a function RA identifier^.., idn, ...) = RA identifier^.., idnmod range_idn, ...) with a modulo operation, mod, applied to one or each index idnwithin the RA identifier.

[0577] The first-mentioned index within the joint index may be referred to as the least significant index. The last-mentioned index within the joint index may be referred to as the most significant index. Within the joint index, any index that is not the most significant index may be referred to as sub-significant index.

[0578] Embodiment 27. The method of any one of embodiments 1 to 26, wherein one or each index idnof the indices within the RA identifier is limited to its range 0 < idn< range_idnfor n = 1, ... .

[0579] Alternatively or in addition, an index within the joint index for the RA identifier may be limited to a first frequency range and a second frequency range for the first set of ROs and the second set of ROs, respectively. E.g., the first frequency range and the second frequency range may be subsets within a full frequency range 0 < f_id < range_f_id of the index f_id for the frequency domain.

[0580] In a variant of any embodiment, one index within the RA identifier may be offset and / or a modulo operator may be applied to the index within the RA identifier. This can reduce the probability of a collision less without limiting the index within the RA identifier.

[0581] An index (e.g., f_id) within the RA identifier as a joint index may be offset for the second set of ROs relative to the same index within the RA identifier used for the first set of ROs. For example:

[0582] RA identifier = RA identifier (s_id, t_id, f_id, u l_ca rrierjd)

[0583] for the first set of ROs

[0584] and

[0585] RA identifier = RA identifier (s_id, t_id, f_id + f_offset, ul_carrier_id) for the second set of ROs.Telefonaktiebolaget LM Ericsson (publ) -54- 301-0298WO P112956WO01

[0586] The f_offset may be equal to the number of locations in the frequency domain for ROs in the first set of ROs (f_number_in_first_set).

[0587] Alternatively or in addition, for the second set of ROs:

[0588] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (modulo (f_id+f_number_in_first_set, range_f_id) + range_f_id x ul_carrier_id)]

[0589] Optionally, f_id is an index of the frequency domain for the second set of ROs (e.g., f_id = f_second_set_id for the frequency domain for the second set of ROs).

[0590] For example, for a NES-set of ROs, i.e., for the second set of NES ROs:

[0591] RA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (modulo (f_idNES+Nnon-NES, range_f_id) + range_f_id x ul_carrier_id)]

[0592] wherein Nnon-NESis the (e.g., maximum) number of locations in the frequency domain for non-NES ROs.

[0593] Embodiment 28. The method (300) of any one of embodiments 1 to 27 , wherein the radio device (100) applies the additional parameter for the determining (302) of the RA identifier only if the second set of ROs overlaps in time with at least one RO of the first set of ROs.

[0594] Embodiment 29. The method (300) of any one of embodiments 1 to 28, wherein the radio device (100) determines the additional parameter is based on or corresponds to a maximum value of the RA identifier or a size of the first set of ROs, and / or wherein the additional parameter shifts a range of the RA identifier for the second set by at least the maximum value or the size.

[0595] Defining the offset with respect to the maximum identifier used for the first set or or size of the first set can ensure that there is no numerical overlap in RA identifiers across sets, e.g. thereby preventing accidental reuse of the same RA identifier and completely resolving potential contention for overlapping transmissions.

[0596] In the determining, the adding of an offset as the additional parameter to the index of the first set may be combined with applying a modulo operation to map the resulting sum into a range for the RA identifier for the second set of ROs.Telefonaktiebolaget LM Ericsson (publ) -55- 301-0298WO P112956WO01

[0597] By adding an offset and applying a modulo operation, embodiments of the NES-capable radio device may reuse the valid frequency-domain index range without requiring an entirely new indexing space. This provides a compact and efficient way to distinguish (e.g., in the frequency dimension) ROs overlapping in time.

[0598] Embodiment 30. The method (300) of any one of embodiments 1 to 29, wherein the receiving (306) comprises the radio device (100) monitoring for the RAR only in a search space indicated by the determined (302) RA identifier distinct for the second set responsive to transmitting the RAP using the RO in the second set of ROs.

[0599] Confining the radio device's RAR monitoring to the RA identifier derived specifically for the second set ensures, embodiments of the radio device can decode the correct RAR when multiple responses may be present (e.g., legacy and NES) and prevents false detections or missed RAR.

[0600] Embodiment 31. The method (300) of any one of embodiments 1 to 30, wherein the radio device ignores any RAR scrambled with a RA identifier corresponding to the first set of ROs when the radio device has used the RO of the second set for transmitting the RAP.

[0601] By disregarding responses not addressed to the NES-capable second set, the radio device avoids reacting to irrelevant RARs intended for other radio devices or legacy procedures, thus improving reliability and preserving correct protocol operation under concurrent resource usage.

[0602] Embodiment 32. The method (300) of any one of embodiments 1 to 31, wherein the additional parameter is applied in the determination (302) of the RA identifier distinct for the second set of ROs regardless of whether there is time overlap with one or more ROs in the first set of ROs

[0603] Embodiments of the method may unify random-access procedures under an extended identifier space. Alternatively or in addition, by consistently applying the extended identifier scheme regardless of time overlap, the radio device simplifies internal handling of random-access transmissions, prevents potential confusion from switching repeatedly between schemes, and / or ensures future-proofing if additional resource adaptations are introduced.Telefonaktiebolaget LM Ericsson (publ) -56- 301-0298WO P112956WO01

[0604] Embodiment 33. The method (300) of any one of embodiments 1 to 32, wherein the radio device (100) selectively transmits (304) on the second set of ROs only if indicated by the network node (200), and wherein the radio device (100) reverts to the first set of ROs in the absence of the indication by the network node (200).

[0605] By allowing the network node to (e.g., dynamically) activate or deactivate the second set of random-access resources, embodiments of the method can dynamically match changing traffic or energy-saving needs, and / or efficiently balancing network load and sleep intervals without compromising an ability of the radio device to perform the RA.

[0606] Embodiment 34. A method (400) performed by a network node (200) in a radio access network (500), the method (400) comprising:

[0607] configuring (401) a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);

[0608] receiving (404), from the radio device (100), a random-access preamble, RAP, on one of the ROs;

[0609] determining (405), based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; and

[0610] transmitting (406), to the radio device (100), a random-access response, RAR, addressed using the determined RA identifier.

[0611] By determining and using an RA identifier that is dependent on whether the radio device used the first or second set of ROs, embodiments of the network node can ensure that RARs are unambiguously addressed. This can avoid collisions or contention that might otherwise arise when ROs coexist in the time domain, thus improving reliability and efficiency of random access.

[0612] Configuring the first set and the second set may comprise sending (e.g., broadcasting) one or more configuration messages to the at least one radio device.

[0613] Embodiment 35. The method (400) of embodiment 34, further comprising changing the RA identifier to be different for two ROs that overlap in the time domain, and optionally differ in the frequency domain.

[0614] Thereby, embodiments can prevent reuse of the same RA identifier for temporally overlapping ROs. By ensuring distinct RA identifiers for overlapping resources, embodiments of the network node can eliminate an ambiguity in addressing RARs whenTelefonaktiebolaget LM Ericsson (publ) -57- 301-0298WO P112956WO01

[0615] multiple ROs intersect in time, thus improving the efficiency of RA signaling and reducing collision rates.

[0616] Embodiment 36. The method (400) of any one of embodiments 34 or 35, wherein the method (400), optionally the configuring (401), further comprises: indicating the second set of ROs via a configuration message sent to the radio device (100); and / or

[0617] activating or deactivating the second set of ROs for the radio device (100), optionally based on a trigger, and wherein the network node (100) reverts to only the first set of ROs if the trigger is absent.

[0618] Dynamically activating or deactivating the second set of ROs allows embodiments of the network node to flexibly control random-access resources in response to changing traffic or operational requirements (as examples of the trigger), supporting efficient resource utilization while maintaining reliable connectivity.

[0619] Embodiment 37. The method (400) of any one of one of embodiments 34 to 36, wherein the determining (405) of the RA identifier comprises computing a baseline value of a baseline RA identifier from one or more indices indicating time or frequency resources of the RO and, if the RO belongs to the second set, adding a non-zero offset to the baseline value.

[0620] Employing an offset to the baseline RA identifier for the second set of ROs can ensure a separate identifier range or reduce a collision rate for some embodiments. This can avoid collisions with baseline RA identifiers associated with the first set of ROs and / or can provide a clear distinction between the different sets of ROs.

[0621] Embodiment 38. The method (400) of any one of embodiments 34 to 37, further comprising the features and the steps of any one of embodiments 2 to 33 or any feature or step corresponding thereto.

[0622] Embodiment 39. A computer program product comprising program code portions for performing the steps of any one of the embodiments 1 to 33 and / or the embodiments 34 to 38 when the computer program product is executed on one or more computing devices (1104; 1204), optionally stored on a computer-readable recording medium (1106; 1206).Telefonaktiebolaget LM Ericsson (publ) -58- 301-0298WO P112956WO01

[0623] Embodiment 40. A radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the radio device (100) comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the radio device (100) is operable to:

[0624] determine a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;

[0625] transmit, to the network node (200), a RA preamble, RAP, using the RO; and receive, from the network node (200) a RA response, RAR, using the RA identifier.

[0626] Embodiment 41. The radio device (100) of embodiment 40, further operable to perform the steps of any one of embodiments 2 to 33.

[0627] Embodiment 42. A radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the radio device (100) being configured to:

[0628] determine a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;

[0629] transmit, to the network node (200), a RA preamble, RAP, using the RO; and receive, from the network node (200) a RA response, RAR, using the RA identifier.

[0630] Embodiment 43. The radio device (100) of embodiment 42, further configured to perform the steps of any one of embodiments 2 to 33.

[0631] Embodiment 44. A network node (200) comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the network node (200) is operable to:

[0632] configure a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);

[0633] receive, from the radio device (100), a random-access preamble, RAP, on one of the ROs;

[0634] determine, based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; and

[0635] transmit, to the radio device (100), a random-access response addressed using the determined RA identifier.Telefonaktiebolaget LM Ericsson (publ) -59 - 301-0298WO P112956WO01

[0636] Embodiment 45. The network node (200) of embodiment 44, further operable to perform any one of the steps of any one of embodiments 34 to 38.

[0637] Embodiment 46. A network node (200) of a radio access network, RAN (500), the network node (200) being configured to:

[0638] configure a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);

[0639] receive, from the radio device (100), a random-access preamble, RAP, on one of the ROs;

[0640] determine, based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; and

[0641] transmit, to the radio device (100), a random-access response addressed using the determined RA identifier.

[0642] Embodiment 47. The network node (200) of embodiment 46, further configured to perform any one of the steps of any one of embodiments 34 to 38.

[0643] Many advantages of the present invention will be fully understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the units and devices without departing from the scope of the invention and / or without sacrificing all of its advantages. Since the invention can be varied in many ways, it will be recognized that the invention should be limited only by the scope of the following claims.

Claims

Telefonaktiebolaget LM Ericsson (publ) -60- 301-0298WO P112956WO01Claims1. A method (300) performed by a radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the method (300) comprising:determining (302) a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;transmitting (304), to the network node (200), a RA preamble, RAP, using the RO; andreceiving (306), from the network node (200), a RA response, RAR, using the RA identifier.

2. The method (300) of claim 1, wherein different RA identifiers are determined (302) for ROs that are equal or overlap in the time domain; and / or wherein the determined (302) RA identifier is dependent on a frequency domain of the RO; and / orwherein different RA identifiers are determined (302) for ROs that are different, optionally offset, in the frequency domain; and / orwherein a RA identifier determined (302) for a RO from the first set is different from a RA identifier determined (302) for a RO from the second set.

3. The method (300) of claim 1 or 2, wherein the first set of ROs are semi-statica I ly configured by the network node (200), optionally using a system information block 1, SI Bl, for RA; and / orwherein the second set of ROs comprises ROs associated with network energy saving, NES, operations of the network node (200) or the RAN (500).

4. The method (300) of any one of claims 1 to 3, wherein the RA identifier is a RA radio network temporary identifier, RA-RNTI.

5. The method (300) of any one of claims 1 to 4, further comprising:acquiring (301), from the network node (200), the first set of ROs and / or the second set of ROs.Telefonaktiebolaget LM Ericsson (publ) -61- 301-0298WO P112956WO016. The method (300) of any one of claims 1 to 5, wherein the RA identifier for the first set of ROs differs from the RA identifier for the second set of ROs by an offset of one index in a joint index for the RA identifier.

7. The method (300) of claim 6, wherein the one index is an index for the frequency domain of the RO, optionally an index indicative of a location in the frequency domain for the RO.

8. The method (300) of any one of claims 1 to 7, whereinRA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_first_set_id+ range_f_id x ul_carrier_id)]for the first set of ROsandRA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_second_set_id+f_number_in_first_set + range_f_id x ul_carrier_id)] for the second set of ROs.

9. The method (300) of claim 8, wherein0 <= f_first_set_id < f_number_in_first_setand0 <= f_second_set_id+f_number_in_first_set < range_f_id.

10. The method (300) of any one of claims 1 to 9, whereinRA identifier = 1 + s_id + range_s_id x [t_id + range_t_id x (f_id+ range_f_id x ul_carrier_id)]f first_offset, for the first set of ROs(second_offset, for the second set of ROsoptionally wherein first_offset = 0 and second_offset = range_s_id x range_t_id x f_number_in_first_set.

11. The method (300) of any one of claims 1 to 10, wherein on index fjd for determining the RA identifier according to the second set is based onan index of the RO in the frequency domain according to the second set anda parameter related to the number of ROs in the frequency domain based on the first set.Telefonaktiebolaget LM Ericsson (publ) -62- 301-0298WO P112956WO0112. The method (300) of any one of claims 1 to 11, wherein the determined (302) RA identifier is a joint index of indices that define the RO.

13. The method (300) of claim 12, wherein the joint index is a function RA identifier = RA identif ier(id i, ...) that is represented or representable or approximated byRA identifier = id i + rangejdi x (id? + rangejdz x (ids + rangejds x (id4 + optionally further indices)))+ constant.

14. The method (300) of any one of claims 1 to 13, wherein the RA identifier is a joint index of at least one of:- an index s_id of a first OFDM symbol of the RO;- an index t_id of a time domain of the RO, optionally an index of a temporal radio resource of the RO, a slot of the RO, a subframe of the RO, or a radio frame of the RO;- an index f_id of a frequency domain of the RO, optionally of a subcarrier of the RO or a radio block of the RO; and- an index u l_ca rrierjd of an uplink carrier of the RO, optionally of a non- supplementary uplink carrier, NUL carrier, or a supplementary uplink carrier, SUL carrier.

15. The method (300) of any one of claims 1 to 14, wherein one or each index idnof the indices within the RA identifier is cyclic within its range0 < idn< range_idnfor n = 1, ... .

16. The method (300) of any one of claims 1 to 15, wherein an index, optionally f_id, within the RA identifier as a joint index may be offset for the second set of ROs relative to the same index within the RA identifier used for the first set of ROs.Telefonaktiebolaget LM Ericsson (publ) -63- 301-0298WO P112956WO0117. The method (300) of any of claims 1 to 16 wherein the RA identifier for the first set of ROs differs from the RA identifier for the second set of ROs by an offset, wherein the offset is an additional parameter.

18. The method (300) of claim 17 wherein RA identifier = 1 + s_id + range_s_id x t_id + range_s_id x range_t_id x f_id + range_s_id x range_t_id x range_f_id x ul_carrier_id + additional parameter.

19. The method (300) of claims 17 or 18 wherein RA identifier = s_id + range_s_id x [t_id + range_t_id x (f_id + range_f_id x ul_carrier_id)] + constant, wherein the constant includes the additional parameter.

20. The method (300) of claims 18 or 19 wherein the additional parameter is zero for the first set of ROs; and / orwherein the additional parameter is a non-zero offset for the second set of ROs.

21. The method (300) of any one of claims 1 to 20, wherein the receiving (306) comprises the radio device (100) monitoring for the RAR only in a search space indicated by the determined (302) RA identifier distinct for the second set responsive to transmitting the RAP using the RO in the second set of ROs.

22. The method (300) of any one of claims 1 to 21, wherein the radio device ignores any RAR scrambled with a RA identifier corresponding to the first set of ROs when the radio device has used the RO of the second set for transmitting the RAP.

23. The method (300) of any one of claims 1 to 22, wherein the radio device (100) selectively transmits (304) on the second set of ROs only if indicated by the network node (200), and wherein the radio device (100) reverts to the first set of ROs in the absence of the indication by the network node (200).

24. A method (400) performed by a network node (200) in a radio access network (500), the method (400) comprising:configuring (401) a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);receiving (404), from the radio device (100), a random-access preamble, RAP, on one of the ROs;Telefonaktiebolaget LM Ericsson (publ) -64- 301-0298WO P112956WO01determining (405), based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; andtransmitting (406), to the radio device (100), a random-access response, RAR, addressed using the determined RA identifier.

25. The method (400) of claim 24, wherein the RA identifier is distinguished for the first set of ROs and the second set of ROs by an offset of one index in a joint index for the RA identifier.

26. The method (400) of claim 24, wherein the one index is an index for the frequency domain of the RO, optionally an index indicative of a location in the frequency domain for the RO.

1. The method (400) of any one of claims 24 to 26, further comprising changing the RA identifier to be different for two ROs that overlap in the time domain, and optionally differ in the frequency domain.

28. The method (400) of any one of claims 24 or 27 , wherein the method (400), optionally the configuring (401), further comprises:indicating the second set of ROs via a configuration message sent to the radio device (100); and / oractivating or deactivating the second set of ROs for the radio device (100), optionally based on a trigger, and wherein the network node (200) reverts to only the first set of ROs if the trigger is absent.

29. The method (400) of any one of claims 24 to 28, further comprising the features and the steps of any one of claims 2 to 23 or any feature or step corresponding thereto.

30. A computer program product comprising program code portions for performing the steps of any one of the claims 1 to 23 and / or the claims 24 to 29 when the computer program product is executed on one or more computing devices (1104; 1204), optionally stored on a computer-readable recording medium (1106; 1206).Telefonaktiebolaget LM Ericsson (publ) -65- 301-0298WO P112956WO0131. A radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the radio device (100) comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the radio device (100) is operable to:determine a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;transmit, to the network node (200), a RA preamble, RAP, using the RO; and receive, from the network node (200) a RA response, RAR, using the RA identifier.

32. The radio device (100) of claim 31, further operable to perform the steps of any one of claims 2 to 19.

33. A radio device (100) capable of performing random access, RA, to a network node (200) of a radio access network, RAN (500), using a first set of RA occasions, ROs, and a second set of ROs, the radio device (100) being configured to:determine a RA identifier for a RA occasion, RO, wherein the RA identifier is dependent on whether the RO is in the first set or the second set of ROs;transmit, to the network node (200), a RA preamble, RAP, using the RO; and receive, from the network node (200) a RA response, RAR, using the RA identifier.

34. The radio device (100) of claim 33, further configured to perform the steps of any one of claims 2 to 23.

35. A network node (200) comprising memory operable to store instructions and processing circuitry operable to execute the instructions, such that the network node (200) is operable to:configure a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);receive, from the radio device (100), a random-access preamble, RAP, on one of the ROs;determine, based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; andtransmit, to the radio device (100), a random-access response addressed using the determined RA identifier.Telefonaktiebolaget LM Ericsson (publ) -66- 301-0298WO P112956WO0136. The network node (200) of claim 35, further operable to perform any one of the steps of any one of claims 24 to 29.

37. A network node (200) of a radio access network, RAN (500), the network node (200) being configured to:configure a first set of random-access occasions, ROs, and a second set of ROs for random access, RA, by at least one radio device (100);receive, from the radio device (100), a random-access preamble, RAP, on one of the ROs;determine, based on whether the received (404) RO is in the first set or the second set, an RA identifier for the received (404) RO; andtransmit, to the radio device (100), a random-access response addressed using the determined RA identifier.

38. The network node (200) of claim 37, further configured to perform any one of the steps of any one of claims 24 to 29.

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