WO2019052631A1

WO2019052631A1 - Technique for differentiated access control

Info

Publication number: WO2019052631A1
Application number: PCT/EP2017/072855
Authority: WO
Inventors: Johan Rune; Stefan Wager
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2017-09-12
Filing date: 2017-09-12
Publication date: 2019-03-21

Abstract

A technique for random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502) is described. As to a method aspect of the technique, system information (506) indicative of an association between RA preambles (508) for performing the RA and at least one of device categories for the radio device (502) and service requirements for the radio communication is received (302) from the RAN (504). At least one of the RA preambles (508) that is, in accordance with the association indicated in the system information (506), associated to at least one of a device category of the radio device and a service requirement of the radio communication is transmitted (306) to the RAN (504).

Description

Technique for differentiated access control

Technical Field

The present disclosure generally relates to a technique for differentiated access control to a radio access network. More specifically, methods and devices are provided for a random access of a radio device to a radio access network.

Background

Many radio access networks (RANs), e.g., for cellular telecommunications networks, use radio access technologies such as Long Term Evolution (LTE) specified by the 3rd Generation Partnership Project (3GPP), which are based on synchronized radio frame structures for uplink and downlink radio communications. When a radio device, such as a 3GPP user equipment (UE), is without uplink synchronization to the RAN or without radio resources granted on a physical uplink control channel (PUCCH) of the RAN, the radio device has to perform a random access (RA) procedure in order to request uplink radio resources and receive a new timing advance.

As described in document US 2009/0268666 Al, the existing RA procedure for 3GPP LTE provides to the RAN information as to UE radio conditions and the size of a message the UE intends to transmit on the uplink. Indicating both the radio channel condition and the size of pending uplink data by selecting a RA preamble is also described in document US 2008/0130588 Al. However, the RAN has no basis for prioritizing or barring UEs performing RA to the RAN.

Hence, in a state without uplink radio resources, which may be the case for the majority of radio devices without current communication, the RAN can perform barring of the radio devices only with the coarse granularity of access classes stored in the subscriber identity module (SIM) of the radio devices using access class barring (ACB) and extended ACB (EAB) specified in the document 3GPP TS 36.331, e.g., version 14.3.0. Conventional ACB and EAB do not allow for barring decisions at the RAN based on cell-specific criteria. The access classes do not even allow for a decision based on function or usage of the radio device, since a majority of radio devices may be randomly assigned the access classes 0 to 9. Moreover, ACB and EAB are inflexible, since the access classes are statically assigned and the RAN can at most indirectly control the barring decision taken at the radio device by configuring radio device parameters including a barring factor and a barring time.

Only after uplink synchronization and granting uplink control resources, an

establishment cause underlying the RA procedure is provided to the RAN in a radio resource control (RRC) connection request, which is also referred to as "message 3" or "Msg3" of the RA procedure. Furthermore, M . Vilgelm and W. Kellerer, in the submission "Binary Contention Resolution for M2M Random Access Prioritization in LTE-A and 5G" to the International Federation for Information Processing 2017, propose leaving the RA preamble sequence and the preamble response unmodified and introducing multiple time slots for the Msg3, which indicate a priority class. Consequently, while a majority of radio devices covered by a cell of the RAN may be out of UL synchronization with the cell or may have no uplink radio resources in the cell, the RAN has no basis for rejecting or prioritizing their RAs, e.g., in case of a shortage of resources.

Summary

There is a need for a technique that enables a radio access network to prioritize or reject radio devices. Preferably, there is a need for a technique that enables the radio access network to prioritize or reject radio devices prior to responding in a random access procedure or prior to providing radio access, e.g., prior to providing radio access on a medium access control layer and/or a radio resource control layer.

Alternatively or in addition, there is a need for a technique that enables a radio access network to prioritize or selectively reject radio devices based on cell-specific and/or time-varying categories for the radio devices. Alternatively or in addition, there is a need for a technique that enables a radio access network to grant selective sizes of radio resources based on cell-specific and/or time-varying categories for the radio devices.

According to one aspect, a method of performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The method comprises or triggers a step of receiving, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The method further comprises or triggers a step of transmitting, to the RAN, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio

communication.

The association, as indicate by the system information, may associate RA preambles to device categories, RA preambles to service requirements and/or RA preambles to combinations of device categories and service requirements. For example, each of the RA preambles may be associated to one of the device categories, to one of the service requirements and/or to one of the combinations of device category and service requirement. This may include some of the RA preambles being associated to device categories, some being associated to service requirements and/or some being associated to combinations of device categories and service requirements. By virtue of the association, the transmitted RA preamble may be associated to the device category of the radio device, the service requirement of the radio

communication and/or a combination of the device category of the radio device and the service requirement of the radio communication. The RAN may be enabled to prioritize or selectively reject the radio device and/or the RA based on the device category and/or the service requirement associated to the RA preamble transmitted by the radio device for performing the RA. The RAN may decide upon the radio device and/or the RA based on the device category and/or the service requirement associated to the RA preamble that is used in the RA. The RAN may selectively provide the RA based on the device category and/or the service requirement associated to the RA preamble transmitted by the radio device.

The transmission of the RA preamble, which is associated to the device category of the radio device and/or the service requirement of the radio communication in accordance with the received association, may enable the RAN to decide and/or prioritize at the beginning of a RA procedure, e.g., in a first step of receiving the RA preamble in the RA procedure. For example, the RAN may prioritize or selectively reject the RA before a medium access control (MAC) layer or a radio resource control (RRC) layer is involved in the RA procedure.

The technique may be implemented to prioritize or reject RAs of radio devices with a granularity defined by the association. The RAs of radio devices may be prioritized or rejected with a granularity according to the association, which is finer than and/or different from conventional access class barring (ACB) or extended ACB (EAB).

Alternatively or in addition, the granularity for prioritizing or rejecting the RAs may be specifically defined for a base station or cell of the RAN. More specifically, the granularity for prioritizing or rejecting the RAs may dependent on a serving cell or the location of the corresponding radio devices. Alternatively or in addition, the granularity for prioritizing or rejecting the RAs may change over time by changing the association that is transmitted by the RAN in the system information.

The technique may enable the RAN (e.g., instead of a decision taken by the radio device) to decide upon a rejection of the RA or to determine a priority of the RA. The device category and/or the service requirement associated to the transmitted RA preamble may enable the RAN to decide upon the priority or the rejection of the RA taking a workload state at the RAN into account. Alternatively or in combination, the technique may enable the RAN to reject the RA procedure earlier in the RA procedure, e.g., at least one step earlier as compared to a mechanism based on an establishment cause or a conventional call admission control (CAC).

When referring herein to device categories (e.g., for the radio device) and/or the service requirements (e.g., for the radio communication) of the association in plural form, the device categories and/or the service requirements may encompass options defined by the association in the system information for distinguishing the radio devices. When referring herein to a device category of the radio device and/or a service requirement of the radio device in singular form, the device category and/or the service requirement may be the one determined by the corresponding radio device among the options defined by the association in the system information. Furthermore, when referring herein to the device category and/or the service requirement associated to the transmitted RA preamble, the device category and/or the service requirement may be the one indicated by the radio device to the RAN by virtue of the transmitted RA preamble.

Moreover, based on the transmitted RA preamble, the RAN may determine a timing advance (TA) for the radio device and/or schedule radio resources for the radio device. A received signal of the RA preamble may be subjected to a convolution at the RAN (e.g., in the time domain) for determining at least one of the transmitted RA preamble and the TA.

The RAN may transmit a RA response in response to the RA preamble. The RA response may include at least one of a scheduling grant indicative of a grant of radio resources and the TA for the radio device.

The RA preamble may also be referred to as a physical RA channel (PRACH) resource. The RA preamble may include a RA preamble sequence. The RA preamble may include at least one of a Zadoff-Chu sequence and a cyclic prefix.

Whenever a step or feature refers to the "RAN", the step or feature may refer to one or more base stations, cells or sectors of the RAN. For example, any base station may serve, cover or define a cell or sector, or multiple cells or sectors, of the RAN.

Whenever a step or feature refers to a "cell", it may also be implemented for a sector of the RAN.

The system information may be received from a base station of the RAN. The RA preamble may be transmitted to a base station of the RAN, e.g., the same base station from which the system information has been received.

The radio communication involving the radio device may include a radio

communication between the radio device and the RAN, e.g., between the radio device and a base station of the RAN, particularly the base station from which the system information had been received and/or the base station to which the RA preamble had been transmitted. The radio communication may include an uplink or a downlink. Alternatively or in addition, the radio communication involving the radio device may include a radio communication between the radio device and another radio device (e.g., for a sidelink). The other radio device may be another instance of a radio device according to the technique. The system information indicative of the association may be broadcasted by the RAN. The system information indicative of the association may be comprised in a master information block (MIB) and/or one or more system information blocks (SIBs).

Alternatively or in addition, the system information indicative of the association may be encoded in one or more synchronization signals.

The association may be specific for the RAN, i.e., specifically for performing the RA to the RAN. Furthermore, the association may be tracking area-specific, base station- specific or cell-specific. Moreover, the system information may be indicative of whether or not the association is applied by the RAN, e.g., in the cell or by the base station of the RAN.

The expression "device categories" may relate to a service, an application and/or a hardware of the radio device. The service or application may underlie (e.g., trigger) the RA. The hardware may perform the RA. The expression "service requirements" may relate to the service or the application, which is performed by or involves the radio device. The expressions "device categories" and "service requirements" may relate to a feature of the radio device as such and/or the service or the application as such, respectively. For example, the expressions "device categories" and "service requirements" do not, or not exclusively, relate to a status of the radio device, e.g., a buffer status for data or size of a message to be transmitted in the radio

communication, such as the size of pending uplink data. Alternatively or in addition, the expressions "device categories" and "service requirements" do not, or not exclusively, relate to a state of a radio channel, e.g., radio conditions, used for the radio communication, such as a downlink channel quality.

The association may map each of the RA preambles to one of the device categories, one of the service requirements or one combination of one of the device categories and one of the service requirements. Optionally, different device categories, different service requirements or different combinations of device categories and service requirements may be associated to different RA preambles. The RAN may apply the mapping of the RA preambles to determine, based on the RA preamble transmitted by the radio device, the device category of the radio device, the service requirement of the radio communication or the combination of the device category and the service requirement.

The association may include disjoint groups (or subsets) of the RA preambles, e.g., a partition of the RA preambles (disjoint shall mean that each RA preamble is only included in one of the groups). A given set of RA preambles may be partitioned into the groups. The given set may be based on one or more root sequences for generating the RA preambles. Based on the grouping (e.g., the partitioning), the RAN may differentiate or categorize radio devices performing the RA. The association may be an injective mapping from the device categories, the service requirements or their combinations to the groups of the RA preambles. That is, different device categories, different service requirements or different combinations of device categories and service requirements may be mapped to different groups of the RA preambles. The radio device may use the mapping of the device categories, the service requirements or their combinations to determine the group including the RA preamble to be transmitted (which may also be referred to as predetermining).

Different groups of the RA preambles may be associated to different device categories. Alternatively or in addition, different groups of the RA preambles may be associated to different service requirements. Alternatively or in addition, different groups of the RA preambles may be associated to different combinations of the device categories and the service requirements. For example, some of the groups may be associated to device categories, and some of the groups may be associated to service requirements. For instance, two groups may be associated to respective quality of service (QoS) classes, and two groups may be associated to respective UE categories.

Each of the groups may be associated to a different one of the device categories, a different one of the service requirements and/or a different combination of one of the device categories and one of the service requirements. In other words, the association may include an injective mapping from the groups of the RA preambles to at least one of the device categories and the service requirements. That is, different groups may be mapped to different device categories, different service requirements and/or different combinations of device categories and service requirements.

One implementation of the technique, may use one type of access category. E.g., either each group may be associated to a QoS class or each preamble group may be associated to a UE category or each preamble group may be associated to a threshold number or range of preceding failed RA attempts, etc. Another implementation may mix different access categories. Each of the groups may be associated to either a different one of the device categories or a different one of the service requirements. Some of the groups may be associated to one type of access categories, e.g. different QoS classes, while other groups may be associated to another type of access categories, e.g. UE categories. For instance, the association may define three groups associated to three different UE categories and one group associated to a number of preceding failed RA attempts (e.g., a threshold number). As long as the number of preceding failed RA attempts of the radio device is less than the threshold number, the radio device selects the group based on its UE category (i.e., one of the three groups associated to UE categories). If the number of preceding failed RA attempts of the radio device is equal to or exceeds the threshold number, the radio device selects a preamble from the fourth group, i.e. from the group associated to the threshold number of preceding failed RA attempts.

Optionally, one of the groups may be associated with multiple device categories. E.g., the UE categories smartphone and laptop may be associated with the same group. Different device categories may be combined into one group according to the granularity necessary for the operation of the RAN, i.e., for serving the corresponding radio device.

Multiple RA preambles may be associated to the same device category, the same service requirement or the same combination of device category and service requirement. To reduce the probability of colliding RA preambles in a contention of the RA, each group may comprise more than one RA preamble.

Optionally, the system information and/or a technical standard may be indicative of one or more further groups defined for the RA preambles. By transmitting a RA preamble of the further groups, the radio device may provide an indication of the size of the message 3 of the RA procedure and/or the radio conditions at the radio device. The technique may be combined or compatible with 3GPP TS 36.300, Sect. 10.1.5.1, e.g., version 8.5.0 or 13.8.0. The technique may be implemented as an extension of 3GPP TS 36.300, Sect. 10.1.5.1.

In one implementation, the Msg3 size and/or the channel condition is a further access class represented by a corresponding further group of the RA preambles. In another implementation, the further groups may also partition the RA preambles. One RA preamble may belong to both a group associated according to the technique with a certain access category (i.e., a device category and/or a service requirement) as well as a further group associated to the size of the Msg3 and/or the channel condition. That is, there may be an overlapping or overlaying between the groups according to the technique and the further groups. The further groups associated to Msg3 size and/or channel condition may overlap or overlay the groups defined by the association of the technique. By way of example, each of the further groups may comprise at least one RA preamble from each of the groups defined by the

association of the technique, or vice versa. That is, each of the groups defined by the association of the technique may be subdivided into subgroups (e.g. two subgroups), wherein each subgroup may be associated with a Msg3 size and/or a channel condition. Alternatively, the one or more further groups associated with Msg3 size and/or channel condition may be divided into subgroups, wherein each subgroup is associated with an access category (i.e., one of the device categories and/or one of the service requirements) according to the technique.

The transmitted RA preamble may be indicative of the at least one of the device category of the radio device and the service requirement of the radio communication according to the association. The transmission of the associated RA preamble may thus convey the device category and/or the service requirement to the RAN. An additional control signaling (which would, for example, require an uplink

synchronization and uplink control radio resources) for conveying the device category and/or the service requirement can be avoided.

The method may further comprise or trigger a step of determining at least one of the device category of the radio device and the service requirement of the radio communication. By virtue of the association indicated in the system information, the determined device category, the determined service requirement or their

combination may determine the RA preamble or the group including the RA preamble, which the radio device transmits, i.e., uses for the RA. For example, the device category and/or the service requirement does not determine the RA preamble per se but one of the groups of the RA preambles, from which the radio device selects (e.g., by a random number generator) the RA preamble used in the

transmission. The radio device may determine (e.g., retrieve from storage) its device category and/or its service requirement, based on which (e.g., via the group) the RA preamble to be transmitted is determined according to the association.

The method may further comprise or trigger a step of selectively receiving a RA response from the RAN in response to the transmitted RA preamble. The selectivity may be based on the at least one of the device category and the service requirement associated to the transmitted RA preamble. Alternatively or in combination, the radio device may selectively receive, from the RAN, a grant for radio resources depending on at least one of the device category and the service requirement associated to the RA preamble. The selective reception (i.e., the selectivity in the reception) of the RA response and/or the grant may relate to whether or not the RA response and/or the grant is transmitted by the RAN. Expiry of a timer for the reception of the RA response may imply a rejection of the RA. The timer may be initiated upon the transmitting of the RA preamble.

The method may further comprise or trigger a step of receiving, from the RAN in response to the transmitted RA preamble, a RA response that is selectively indicative of a rejection or a grant of radio resources of the RAN. The selective indication (i.e., the selectivity in the indication) of the RA response may relate to whether the rejection or the grant is transmitted by the RAN. The selectivity, i.e., whether the rejection or the grant is indicated by the RA response, may be based on at least one of the device category and the service requirement associated to the transmitted RA preamble.

The transmitted RA preamble may include or imply a scheduling request (SR), e.g., for the radio resources of an uplink transmission to the RAN (e.g., in a data plane or a control plane). The RA preamble may be regarded as the SR. The grant (e.g., in the RA response) may relate to the radio resources requested by the SR. The grant may also be referred to as a scheduling grant. The absence of a grant for the SR may imply the rejection.

The rejection may be a rejection of the SR (e.g., a rejection of the requested radio resources), a rejection of the RA procedure (e.g., a rejection of the RA introduced by the transmitted RA preamble) and/or a rejection of the radio device as such.

The method may further comprise or trigger a step of receiving, from the RAN, a RA response to the transmitted RA preamble, wherein the RA response is indicative of a grant of radio resources of the RAN. The granted radio resources may depend on at least one of the device category and the service requirement associated to the transmitted RA preamble. For example, a size of the granted radio resources and/or a timing of the granted radio resources may depend on at least one of the device category and the service requirement associated to the transmitted RA preamble.

The size may relate to a bandwidth or a number of resource blocks of the granted radio resources. The timing may relate to a delay between the transmission of the RA preamble as the SR and the reception of the RA response as the scheduling grant. By way of example, the higher the priority based on the device category and/or the service requirement, the more radio resources may be granted (i.e., the greater the size) and/or the earlier the radio resources may be scheduled (i.e., the less the delay) by the RAN.

At least one of the selective reception of the RA response, the RA response, the selective indication in the RA response, the granted radio resources, the size of the granted radio resources and the timing of the granted radio resources may further depend on the availability of resources at the RAN. The resources at the RAN may include radio resources, processing resources and/or backhaul resources at the RAN. The resources at the RAN may include resources used by the RAN or resources that use the RAN (e.g., bearer resources or resources of the non-access stratum).

In the case of a shortage of the resources at the RAN, the RAN may prioritize or reject the RA directly after receiving the RA preamble. For example, the received RA response may depend on at least one of the service requirement indicated by the transmitted RA preamble and the availability of the resources at the RAN.

The resources at the RAN may include the radio resources of the RAN. For example, the resources at the RAN may include the radio resources used for the radio communication involving the radio device and/or for other radio communications involving other radio devices. Alternatively or in addition, the resources at the RAN may include processing resources in the RAN, e.g. in the base station.

Alternatively or in addition, the resources at the RAN may include interfaces at the RAN (e.g., other than a radio interface of the RAN to the radio devices) and/or resources used by the RAN for communication beyond the RAN (e.g., outside of base stations of the RAN). The resources at the RAN may include a backhaul connection between base stations of the RAN or a backhaul connection between the RAN and a core network (CN).

The service requirements of the association may include bearers (e.g., radio bearers) or types of bearers (e.g., default or dedicated bearers) for the radio communication. The types of radio bearers may include at least one of bearers with guaranteed bit rate (GBR bearers) and non-GBR bearers.

The service requirement associated to the transmitted preamble may correspond to or may include the bearer or the type of bearer of the radio communication. The RA preamble transmitted by the radio device may be associated to the bearer or the type of bearer preferred by the radio device for the radio communication. The RA preamble may be associated to the bearer or the type of bearer in accordance with the association indicated in the system information. Alternatively or in addition, the device category of the radio device may correspond to, or may imply, the bearer or the type of bearer for the radio communication.

Herein, the expression "bearer" may comprise a radio part and/or a wired part of a communication path. The communication path may extend all the way through a mobile communication network, i.e. all the way between the radio device and a far edge of the CN, e.g., to a gateway node in the CN, such as a packet data network (PDN) gateway, which is bordering with external networks, e.g., in both

communication directions. The expression "radio bearer" may comprise only the radio part of the (overall) bearer, e.g. a part between the radio device and the base station of the RAN of the mobile communication network, e.g., in both

communication directions. When the radio device is in an RRC idle mode (e.g., an

RRCJDLE state), only non-radio parts of the bearer may exist. There may be a "gap" in the bearer between the radio device and the base station of the RAN. The radio bearer may exist only when the radio device is in an RRC connected mode (e.g., an RRC_CONNECTED state and, at least to some logical extent, in an RRCJNACTIVE state).

The device categories (e.g., the UE categories) of the association for the radio device may include at least one of Internet of Things devices, actuators, sensors, controllers, embedded devices, devices for machine-type communication, devices for ultra- reliability low-latency communication, user devices, smartphones, laptops, handheld devices, wearable devices and head-mounted displays.

Alternatively or in addition, the device categories of the association may include at least one of parameters for the RA (briefly: RA parameter), subscription classes and access classes. The transmitted RA preamble may be associated to at least one of a parameter for the RA of the radio device, a subscription class of the radio device and an access class of the radio device. The access classes may include the access classes 11 to 15 according to the document 3GPP TS 22.011, Sect. 4.2 (e.g., version 14.6.0).

The parameters for the RA may be indicative of at least one of a transmit power used for transmitting the RA preamble, a number or range of preceding failed RA attempts by the radio device (e.g., attempts of performing the RA procedure with the RAN) and a persistence of the RA. The persistence of the RA may comprise a value (e.g., a barring time) or a range for a backoff timer of the RA procedure or a maximum number (e.g., the threshold number) of RA attempts. Alternatively or in addition, the device categories may or may not include a barring factor as a RA parameter.

The radio device may increment a counter (e.g., referred to as failure counter) for each failed RA procedure, e.g., if the radio device does not detect a physical downlink control channel (PDCCH) transmission (e.g., the RA response or Msg2) with its radio network temporary identifier (RNTI), e.g., a cell RNTI (C-RNTI) in the connected mode or a RA-RNTI. The RA response (or Msg2) may be addressed to one of a set of RA- RNTIs on the PDCCH. The RA-RNTI, to which the radio device is listening, may be defined by the time and frequency resource upon which the RA preamble (or Msgl) was transmitted. The Msg4 may be addressed to a temporary C-RNTI (TC-RNTI), which may be allocated by the Msg2. Upon completion of the RRC connection based on the Msg4, the TC-RNTI may be regarded as the C-RNTI of the radio device.

Alternatively or in addition, the radio device may increment the counter for the failed RA procedures, if the radio device does not find a match between the identity (e.g., the TC-RNTI or the C-RNTI) received in a fourth step (e.g., in an RRC signaling response or Msg4) of the RA procedure and the identity (e.g., the TC-RNTI or the C- RNTI) transmitted in a third step (e.g., in an RRC signaling request or Msg3) of the RA procedure.

Alternatively or in addition, the radio device may increment the counter for the failed RA procedures, if the radio device does not receive the RRC signaling response or Msg4 in the fourth step of the RA within a predefined time from transmitting the RRC signaling request or Msg3 in the third step. Otherwise, the radio device may reset the counter for the failed RA procedures (e.g., set the counter to zero).

In a first implementation, failure to receive a response or Msg2 to the transmitted RA preamble may increase the failure counter. In a second implementation, which is combinable with the first implementation, failure to receive an RRC signaling response or Msg4 targeting the radio device may increase the failure counter.

At least one of the device category of the radio device, the RA parameter of the radio device, the subscription class of the radio device and the access class of the radio device may be stored at the radio device. The information may be stored in a universal subscriber identity module (USIM) or an embedded universal integrated circuit card (eUICC) at the radio device. The information stored at the radio device may be read for determining the RA preamble in accordance with the association.

The service requirements of the association may include at least one of application classes for an application underlying the radio communication, QoS requirements for the radio communication and quality of service class indicators (QCIs) for the radio communication. The transmitted RA preamble may be associated to at least one of a QoS requirement of the radio communication and a QCI of the radio communication. Based on the QoS requirement associated to the transmitted RA preamble, the RAN may prioritize the radio device. The QoS or QCI may correspond to requirements as to at least one of the latency of the radio communication (e.g., a time limit), the reliability of the radio communication (e.g., a maximum bit-error ratio, BER, or block- error ratio, BLER) and the data rate of the radio communication (e.g., a minimum bit rate or GBR bearer).

The application classes may include conversational voice, conversational video, realtime gaming, vehicle communication (V2X) and/or virtual reality. Each of the application classes may imply a QoS requirement or a QCI. The service requirement of the radio communication may be derived from an application identifier (or app ID), e.g., when receiving application from a server of an app store. The app ID and/or the application class may be defined and received from the server of the app store.

The method may further comprise or trigger a step of performing or initiating a service or an application at the radio device. The service or the application may trigger performing the RA. The application performed by the radio device may include a client process using the radio communication for performing the service. The service requirement associated to the transmitted RA preamble may be indicative of at least one of an application class of the application, a QoS requirement of the service and a QCI of the service.

The RAN may include a plurality of cells (e.g., each defined by a base station of the RAN). The association may be related to (e.g., may apply only to) a cell covering the radio device. The radio device may camp on the cell, e.g., in an RRC idle mode (e.g., an RRCJDLE state). Alternatively, the radio device may be in an RRC connected mode (e.g., an RRC_CONNECTED state) with the cell, e.g., without uplink synchronization with the cell or without uplink control radio resources of the cell.

The RA preamble may be transmitted on a radio resource. Different radio resources may be associated to different device categories, different service requirements or different combinations of device categories and service requirements. Optionally, other messages (e.g., the RRC connection request) of the RA procedure are transmitted on radio resources as scheduled by the RAN without choosing the radio resource at the radio device.

Each of the RA preambles may correspond to a sequence (e.g., a sequence of complex numbers) and/or a RA resource (e.g., one or more resource elements in time and/or frequency). According to the association, disjoint sets of sequences and/or RA resources may be associated to different device categories, different service requirements or different combinations of device categories and service

requirements.

The RA preamble for the transmission may be determined by determining one of the sets or one of the groups according to the association. The RA preamble for the transmission may be determined within the determined set or group using a random- number generator.

The method may be performed by the radio device, e.g., in a state without uplink synchronization with the RAN or without radio resources granted by the RAN for uplink control signaling. The radio device may be in a connected mode (e.g., an

RRC_CONNECTED state) with the RAN, e.g., according to an RRC protocol of the RAN. In the RRC connected mode, the radio device may be without uplink synchronization, e.g., after expiry of a timing advance (TA) of the radio device. Alternatively or in addition, data originating from the radio device may trigger the RA (e.g., with or without uplink synchronization).

Alternatively or in addition, the method may be performed by the radio device in an idle mode (e.g., an RRCJDLE state) relative to the RAN. The radio device may be in an idle mode with the RAN, e.g., according to the RRC protocol of the RAN. The radio device may periodically or event-driven perform the RA to the RAN. For example, the radio device may be an Internet of Things (loT) device, and a measurement of the radio device may trigger the RA.

According to another aspect, a method of providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The method comprises or triggers a step of transmitting, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The method further comprises or triggers a step of receiving, from the radio device, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

The method may be performed by the RAN, e.g., by the base station or cell of the RAN. Whenever referring to the "RAN", the steps may be performed or the features may be implemented at the base station of the RAN. The "base station" may encompass any station that is configured to provide radio access to the radio device.

The base station may serve a plurality of radio devices. The method may be implemented in relation to multiple instances of the radio device (briefly referred to as "radio devices").

The system information may be transmitted (e.g., broadcasted) from the RAN, e.g., from a base station or a cell of the RAN. The RA preamble may be received at the RAN, e.g., at the base station or cell of the RAN.

According to the association, the received RA preamble may be indicative of at least one of the device category of the radio device and the service requirement of the radio communication.

The RAN may determine at least one of the device category of the radio device and the service requirement of the radio communication based on the received RA preamble and the association indicated in the system information. The RAN may decide as to at least one of a rejection, a response, a scheduling grant and a priority of the radio device or the RA based on the device category and/or the service requirement associated to the received RA preamble. The RAN may prioritize the radio device and/or the RA, or may determine whether to reject or respond to the RA preamble, based on the device category associated to the RA preamble and/or the service requirement associated to the RA preamble.

The RAN may receive RA preambles from a plurality of radio devices. The step of prioritizing or determining may be based on the device categories and/or the service requirements, which are associated to the received RA preambles of the plurality of radio devices in accordance with the association indicated in the system information. Depending on at least one of the device category and the service requirement associated to the received RA preamble, the RAN may selectively transmit a RA response in response to the received RA preamble to the radio device. The RA response may be addressed to the radio device based on the RA preamble received from the radio device.

The RAN may selectively grant radio resources for the radio device depending on the device category and/or the service requirement associated to the received RA preamble. Alternatively or in combination, the RAN may selectively reject the RA of the radio device, e.g., by not responding to the RA preamble. For example, the RA response may be indicative of the granted radio resources.

The other method aspect may further comprise any feature or step, or a

corresponding feature or step, disclosed in the context of the one method aspect, and vice versa. In any aspect, the radio communication involving the radio device may include at least one of an uplink (UL) transmission from the radio device, a downlink (DL) transmission to the radio device and a sidelink (SL) transmission from or to the radio device. The radio device may be configured for peer-to-peer communication (e.g., on a SL) and/or for accessing the RAN (e.g. an UL and/or a DL). The radio device may be a user equipment (UE, e.g., a 3GPP UE), a mobile or portable station (STA, e.g. a Wi-Fi STA), a device for machine-type communication (MTC) or a combination thereof. Examples for the UE and the mobile station include a mobile phone and a tablet computer. Examples for the portable station include a laptop computer and a television set. Examples for the MTC device include robots, sensors and/or actuators, e.g., in manufacturing, automotive communication and home automation. The MTC device may be implemented in household appliances and consumer electronics. Examples for the combination include a self-driving vehicle, a door

intercommunication system and an automated teller machine.

Examples for the base station may include a 3G base station or Node B, 4G base station or eNodeB, a 5G base station or gNodeB, an access point (e.g., a Wi-Fi access point) and a network controller (e.g., according to Bluetooth, ZigBee or Z-Wave).

The RAN may be implemented according to the Global System for Mobile

Communications (GSM), the Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE) and/or New Radio (NR).

The technique may be implemented on a Physical Layer (PHY), the MAC layer, a Radio Link Control (RLC) layer and/or the RRC layer of a protocol stack for the radio communication.

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 method aspects 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 via a data network, e.g., via the Internet, the RAN and/or the base station. 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.

As to one device aspect, a device for performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device is configured to perform or trigger the one method aspect. Alternatively or in addition, the device may comprise a receiving unit configured to receive, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device may further comprise a transmitting unit configured to transmit, to the RAN, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

As to another device aspect, a device for providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device is configured to perform or trigger the other method aspect. Alternatively or in addition, the device may comprise a transmitting unit configured to transmit, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device may further comprise a receiving unit configured to receive, from the radio device, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

As to a further aspect, a device for performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device comprises at least one processor and a memory. Said memory comprises instructions executable by said at least one processor whereby the device is operative to receive, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication.

Execution of the instructions further causes the device to be operative to transmit, to the RAN, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

As to a further aspect, a device for providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device comprises at least one processor and a memory. Said memory comprises instructions executable by said at least one processor whereby the device is operative to transmit, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio

communication. Execution of the instructions further causes the device to be operative to receive, from the radio device, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

As to a still further aspect, a device for performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device may comprise one or more modules for performing the one method aspect. Alternatively or in addition, the device comprises a reception module for receiving, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device further comprises a transmission module for transmitting, to the RAN, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

As to a still further aspect, a device for providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device is provided. The device may comprise one or more modules for performing the other method aspect. Alternatively or in addition, the device comprises a transmission module for transmitting, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device further comprises a reception module for receiving, from the radio device, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

The device (or any node or station for embodying the technique) may further include any feature disclosed in the context of the method aspect. Particularly, any one of the units and modules, or a dedicated unit or module, may be configured to perform or trigger one or more of the steps of any one of the method aspect.

Brief Description of the Drawings

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

Fig. 1 shows a schematic block diagram of a device for performing random access;

Fig. 2 shows a schematic block diagram of a device for providing random access;

Fig. 3 shows a flowchart for a method of performing random access, which is implementable by the device of Fig. 1;

Fig. 4 shows a flowchart for a method of providing random access, which is implementable by the device of Fig. 2; Fig. 5 shows a schematic signaling diagram for embodiments of the devices of Figs. 1 and 2;

Fig. 6 schematically illustrates a first example of an association for random access preambles;

Fig. 7 schematically illustrates a second example of an association for random access preambles;

Fig. 8 schematically illustrates a third example of an association for random access preambles;

Fig. 9 schematically illustrates a fourth example of an association for random access preambles;

Fig. lOschematically illustrates a cell comprising an embodiment of the device of Fig. 2 and multiple embodiments of the device of Fig. 1;

Fig. llshows a schematic block diagram of an embodiment of the device of Fig. 1; and

Fig. 12shows a schematic block diagram of an embodiment of the device of Fig. 2. Detailed Description

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 5G New Radio (NR) implementation, it is readily apparent that the technique described herein may also be implemented in any other radio network, including 3GPP LTE or a successor thereof, Wireless Local Area Network (WLAN) according to the standard family IEEE 802.11, Bluetooth according to the Bluetooth Special Interest Group (SIG), particularly Bluetooth Low Energy and Bluetooth broadcasting, and/or ZigBee based on IEEE 802.15.4.

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 at 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.

Fig. 1 schematically illustrates a block diagram of a device for performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device. The device is generically referred to by reference sign 100.

The device 100 comprises a reception module 102 that receives, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device 100 further comprises a transmission module 106 that transmits, to the RAN, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

Optionally, the device 100 comprises a determination module 104 that determines, prior to the transmission of the RA preamble, the device category and/or the service requirement based on which the RA preamble for the transmission is determined.

The device 100 may be connected to and/or part of the radio device. The device 100 may be embodied by or at the radio device, nodes connected to the radio device and controlled by the RAN or a combination thereof.

Fig. 2 schematically illustrates a block diagram of a device for providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device. The device is generically referred to by reference sign 200.

The device 200 comprises a transmission module 202 that transmits, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The device further comprises a reception module 204 that receives, from the radio device, at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

Optionally, the device 200 comprises a determination module 206 that determines, after the reception of the RA preamble and using the association, the device category and/or the service requirement based on which the RA may be controlled.

The device 200 may be connected to and/or part of the RAN. The device 200 may be embodied by or at a base station of the RAN, nodes connected to the RAN for controlling the base station or a combination thereof. Any of the modules of the devices 100 and 200 may be implemented by units configured to provide the corresponding functionality.

The base station may encompass a network controller (e.g., a Wi-Fi access point) or a radio access node (e.g. a 3G Node B, a 4G eNodeB or a 5G gNodeB) of the RAN. The base station may be configured to provide radio access. Alternatively or in addition, the one or more radio devices may include a mobile or portable station or a radio device connectable to the RAN. Each radio device may be a user equipment (UE) and/or a device for machine-type communication (MTC). Two or more radio devices may be configured to wirelessly connect to each other, e.g., in an ad-hoc radio network or via 3GPP sidelinks.

Fig. 3 shows a flowchart for a method 300 of performing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device. The method 300 comprises a step 302 of receiving, from the RAN, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The radio device transmits to the RAN in a step 306 at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

In an optional step 304, the radio device determines, prior to the transmission 306 of the RA preamble, the device category and/or the service requirement based on which the RA preamble for the transmission 306 is determined.

The method 300 may be performed by the device 100, e.g., at or using the radio device. For example, the modules 102, 104 and 106 may perform the steps 302, 304 and 306, respectively.

Fig. 4 shows a flowchart for a method 400 of providing random access (RA) to a radio access network (RAN) for a radio communication involving a radio device. The method 400 comprises a step 402 of transmitting, to the radio device, system information indicative of an association between RA preambles for performing the RA and at least one of device categories for the radio device and service requirements for the radio communication. The RAN receives from the radio device in a step 404 at least one of the RA preambles that is, in accordance with the association indicated in the system information, associated to at least one of a device category of the radio device and a service requirement of the radio communication.

In an optional step 406, after the reception 404 of the RA preamble and using the association, the device category and/or the service requirement is determined, based on which the RAN may control the RA. Based on the received RA preamble and the association, the RAN can decide upon the RA in the step 406. The decision depends on the device category of the radio device and/or the service requirement of the radio communication derived from the received RA preamble and the association.

The method 400 may be performed by the device 200, e.g., at or using the base station of the RAN. For example, the modules 202, 204 and 206 may perform the steps 402, 404 and 406, respectively.

Based on the device categories and/or the service requirement conveyed from the radio device to the RAN in the steps 306 and 404, respectively, the RAN may control, allocate and/or use access resources and/or transmission resources (in particular radio resources) and/or cellular networks (in particular base stations). The technique may be implemented to control and/or use any access control mechanism and/or any QoS prioritization mechanism based on the device category and/or the service requirement received from each of the one or more radio devices accessing the RAN .

Fig. 5 schematically illustrates a signaling diagram 500 resulting from the methods 300 and 400 being performed by the devices 100 and 200, respectively. The devices 100 and 200 are implemented at the radio device 502 and the RAN 504 (e.g., a base station of the RAN), respectively.

While a conventional barring mechanism is based on coarse and static access classes, the system information 506 transmitted (e.g., broadcasted) from the RAN 504 to the radio device 502 according to the steps 302 and 402 can be changed according to a current workload or capabilities of the RAN 504. By transmitting the association in the system information 506, the RAN 504 can define the differentiation of the radio devices 502.

By receiving the RA preamble 508 indicative of the device category and/or the service requirement according to the steps 306 and 404, the RAN 504 can control in the step 406 the accesses of each radio device 502. Based on the device category and/or the service requirement conveyed from each of radio devices 502 to the RAN 504, the RAN may be enabled for a differentiated access control of multiple radio devices 502 performing the RA to the RAN 504.

For example, transmitting a RA response 512 from the RAN 504 to radio device 502 may be subject to the decision 406. Moreover, if the RA response 512 is transmitted, the RA response 512 may comprise a scheduling grant for radio resources, the size of which is subject to the decision 406. The RA response 512 may further comprise a timing advance for synchronization of the uplink of the radio device 502.

Using the granted uplink radio resources, the radio device transmits a connection request 514, which may comprise a Temporary Mobile Subscriber Identity (TMSI) and/or an establishment cause. As opposed to a conventional access barring mechanism that can decide upon the RA not until reception of the establishment cause at the end of the RA procedure, the technique can enable the RAN 504 to decide in the step 406 at the beginning of the RA procedure.

Depending on at least one of the device category associated to the received RA preamble 508, the service requirement associated to the received RA preamble 508 and the establishment cause, the RAN 504 transmits a connection setup message 516 to the radio device 502. For example, transmitting the connection setup message 516 from the RAN 504 to radio device 502 may be subject to the decision 406.

The RA preambles 508 available for the RA in the RAN 504 (e.g., in a tracking area of the RAN 504) may be divided into groups according to the association. That is, the association may include a grouping of the RA preambles 508 available for the RA. For example, all RA preambles 508 within the same group may be associated to the same device category and/or service requirement.

Fig. 6 schematically illustrates a first example of the association 600 comprising a plurality of RA preambles 508 that are divided in a plurality of groups 604. The association 600 associates the different groups 604 to different of the device categories and/or the service requirements. That is, RA preambles 508 belonging to different groups 604 are different in the association 600 as to at least one of the device categories and/or the service requirements.

The groups 604 of the association 600 are used by the RAN 504 for access control (e.g., to selectively enforce access barring) and/or a prioritization (e.g., to selectively serve). The barring may include suppressing the RA response 512 or rejecting the connection request 514. The prioritization may be improved by changing the groups 604 defined in the system information as compared to a previous (e.g., for a more well-founded, flexible and/or fine-grained prioritization). Furthermore, the size of granted UL radio resources may be controlled in the step 406.

Since a division of the available RA preambles into groups may have negative consequences on a collision probability (e.g., depending on the scenario and/or situation), the RA preamble group division is preferably applied when (e.g., only if) resources (e.g., radio resources) are scarce at the RAN 504, such that some type of access barring is to be enforced or a stricter (e.g., more efficient) scheduling is needed, e.g., in terms of prioritization and/or UL grant sizes in the step 406.

The association 600 may be a dynamic mapping from (e.g., changing) groups 604 of the RA preambles 508 to access categories, i.e., the device categories and/or the service requirements. The association 600, e.g., the definition of the groups, may be specific for a cell of the RAN 504 or a tracking area of the RAN 504. Embodiments of the devices 100 and 200 can enable great flexibility and

configurability of the type of differentiation that this mechanism can support by indicating the association 600 in the system information 506. The association 600 indicated in the system information 506 may be dynamically changed.

Examples for the device categories and/or the service requirements comprise a differentiation (e.g., of the radio devices 502 and their attempted radio

communications) based on bearer, QoS, UE category, subscription class, application class, number of preceding failed random access attempts and/or random access preamble transmit power. Examples of what is controlled based on the device category and/or the service requirement comprise the prioritization of the radio device, the UL grant size and/or whether the access is accepted or rejected.

The enriched information (i.e., the device category and/or the service requirement associated to the RA preamble 508) that is made readily and timely available to the RAN 504 through the choice provided by the device 200 in the step 402 and taken by the device 100 in the step 306, and the dynamic and flexible ways to apply the information in the step 406, can provide an efficient and flexible tool for the network (e.g., the RAN and/or the CN) to manage and efficiently use its resources as well as enforce a well-founded and fair differentiation of the radio devices when resources are scarce.

The technique can be implemented in addition to an existing access control. In an LTE implementation, the access control includes Access Class Barring (ACB) and, e.g., for MTC devices as the radio devices 502, Extended ACB (EAB). The existing access control may be based on parameters announced in the broadcasted system information. In accordance with the ACB mechanisms, all regular UEs (e.g., including the radio devices 502) are members of one out of ten randomly allocated access classes (e.g., classes numbered 0 to 9), which is stored in the USIM of the respective UE.

In addition, there are special access classes (e.g., the five classes 11 to 15), which are used only for special types of accesses. The special access classes include class 11 for use by the Public Land Mobile Network (PLMN use, e.g., including the RAN 504); class 12 for security services; class 13 for public utilities (e.g. water or gas suppliers); class 14 for emergency services; and class 15 for PLMN staff.

Moreover, class 10 governs a possible barring of emergency calls. If access class 10 is indicated as barred in a cell, UEs (e.g., including the radio devices 502) with access class 0 to 9 or without an International Mobile Subscriber Identity (IMSI) are not allowed to initiate emergency calls in the cell (e.g., to avoid anonymous abuse of emergency services). For UEs with access classes 11 to 15, emergency calls are not allowed if both access class 10 and the relevant access class 11 to 15 are barred. Otherwise, emergency calls are allowed for those UEs.

For regular UEs belonging to access classes 0 to 9 the barring status of a cell is governed by a "barring rate" parameter (set to a value between 0 and 1), which is also called "access class barring factor", and a "mean duration of access control" parameter. To determine whether to consider a cell as barred, the UE generates a random value between 0 and 1, compares it with the broadcast barring rate parameter and, if the random number is greater than the barring rate, the UE determines the cell as barred for access. The UE also calculates a barring time, i.e. the time until the UE is allowed to make its next access attempt, based on the random value and the broadcast mean duration of access control parameter. The access class in the range 0 to 9 (stored in the USIM of the UE) is used in conjunction with EAB, wherein a broadcasted bitmap corresponding to the access classes indicates whether the cell is barred for UEs belonging to a certain access class.

Through additional parameters broadcasted in the system information, the LTE RAN (i.e. E-UTRAN) can further differentiate the access control and/or barring status based on the different access types "mobile originating data" and "mobile originating signaling".

Regarding QoS prioritization, this is the responsibility of the scheduler in the base station, which maintains per bearer queues, matching the QoS per bearer granularity. For 5G NR, it has been proposed to improve the means for prioritization to enable more flexible prioritization schemes than merely based on the bearer QoS. To this end, it has been proposed to enable a UE to provide information in its scheduling request regarding the nature of the pending UL data that triggered the scheduling request, with the purpose to aid the RAN scheduler to perform more granular prioritization and also to adapt the size of a possible UL grant. The additional scheduling request information in scheduling requests may be used to improve the prioritization (e.g., UL grant allocation) and flexibility, and thus can improve the possibilities of the RAN for efficient radio resource management/control. However, this mechanism alone still requires that the UE has UL signaling resources for scheduling request transmission, e.g. on a physical uplink control channel (PUCCH) in an LTE implementation, and is U L synchronized (i.e., has a valid timing advance value).

UEs that lack either signaling resources for the scheduling request or UL

synchronization have to request transmission resources through the RA procedure, which can be improved by the technique described herein. Hence, a majority of the UEs as the radio devices 502 in the coverage range of the RAN 504 may exclusively benefit from the technique described herein and, e.g., not an extended scheduling request information. Moreover, by implementing the technique, the network (e.g., RAN 504 and/or CN) has tools for access control and prioritization beyond the granularity of existing access barring mechanisms (e.g., ACB and/or EAB). Further, the technique is not limited to UEs in the idle mode. Still further, the existing access barring mechanism is a rather rigid means for access control, since it relies on the UE reading the system information prior to accessing the RAN and applying the current access barring status. Particularly, the system information may be transmitted not very frequently, so that the existing access barring mechanisms are slow and unsuitable to adapt to fast variations of the traffic load. The same inertness holds true for the barring duration time calculated by the UE based on a broadcasted parameter "mean duration of access control", which governs how long a UE that determines itself as barred has to wait until it may reattempt to access the RAN.

This can be avoided by implementing the technique, so that the RAN 504 is enabled to define in the system information 506 the criteria (in terms of device categories and/or the service requirements) that are applied to the radio devices attempting to perform the RA to the RAN 504 by relating the choice of the RA preamble to the fulfilment of the criteria. As soon as the RAN 504 receives the RA preamble 508 as the first step of the RA procedure, the RAN 504 is in a position to determine in the step 406 as to how to proceed with the RA based on the device category and/or the service requirement implied by the received RA preamble 508.

Hence, the technique may enable the RAN 504 to decide on each RA at an earlier stage and/or based on criteria controlled by the RAN 504. The criteria, i.e., the device categories and/or the service requirements of the association 600 in the system information 506, may include some or all of the existing access classes, e.g., the special access classes.

Preferably, the RA preambles 508 of the association 600 are partitioned in groups 604, each group 604 comprising one or more of the RA preambles 508. Each group 604 is associated to the at least one of the device categories and service

requirements. In one variant, the groups 604 defined by the association 600 also comprise some or all of the existing access classes.

In another variant, which is schematically illustrated in Fig. 7, the association 600 comprises the groups 604, which partition the RA preambles 508. In addition, the association 600 comprises further groups 606, which also partition the RA preambles 508. For example, each of the RA preambles 508 is in both one of the groups 604 and one of the further groups 606. Each of the further groups 606 may be associated to one of the existing access classes.

In any embodiment, the RA preamble 508 transmitted in the step 306 may be indicative of multiple device categories, indicative of multiple service requirements, or indicative of a combination of one or more device categories and one or more service requirements. Fig. 8 schematically illustrates a second example for the association 600. The second example of the association 600 associates each of the RA preambles 508 to a set of three service requirements 802, 804 and 806. In the example illustrated in Fig. 8, each RA preambles 508 is associated to a combination of a reliability requirement 802 (e.g., defined in terms of a packet error ratio or rate, PER), a latency requirement 804 (e.g., a packet delay budget defined in milliseconds or transmission time intervals, TTIs) and a binary requirement, namely whether the bearer has a guaranteed bit rate (GBR) or not.

While the multiple criteria (in terms of device categories and/or the service requirements) are illustrated on orthogonal axes in Fig. 8, an association 600 for associating each RA preamble 508 to multiple criteria may be implemented by multiple partitions (e.g., three partitions) of the RA preambles 508. That is, the association 600 defines multiple group divisions (e.g., three group divisions) of the same RA preambles 508, so that each RA preamble 508 is associated to multiple groups 604 (e.g., three groups), namely exactly one group of each partition. Each partition is associated to exactly one of the criteria, and each group is associated to a value for the corresponding one of the criteria. Herein, expressions "group division" and "partition" may be interchangeable. Furthermore, herein the expressions "criteria" and "categories" may be interchangeable.

In any embodiment (including the association 600 with only one group division in Fig. 6 and the association 600 with three group divisions in Fig. 8), to indicate an association 600 with a group division applied to the RA preambles 508, there is an indicator in a Master Information Block (MIB) and/or in one or more System

Information Blocks (SIBs) containing RA related configuration data, which is referred to as the system information herein. The system information indicates that a group division of the RA preambles 508 is applied and the type of differentiation that the group division supports, which is referred to as the association 600 herein . To support the indicated type of differentiation, the RA preambles 508 are divided into groups 604 mapping to different categories (i.e., the device categories and/or the service requirements) that are relevant for the desired type of differentiation.

Possible types of differentiation and categorization within each type, i.e., examples of the device categories and the service requirements, are described.

Different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different bearers (as the device categories or the service requirements). For example, each RA preamble group 604 may map to a radio bearer (RB), i.e. the radio bearer the pending UL data will be transmitted on. If UL data is pending for multiple bearers, the preamble group preferably maps to the one that has the highest priority (e.g., if highest priority is known to the UE). To this end, each RA preamble group 604 may map to a RB identifier.

Alternatively, for the purpose of mapping to RA preamble groups 604, each bearer may conceptually be given a number that is (e.g., not to be signaled in the step 302) used as part of the mapping. For instance, the bearer with the lowest RB identifier in the radio device 502 may be assigned the number 1, the bearer with the second lowest RB identifier in the radio device 502 may be assigned the number 2, etc. Each such number may map to one of the groups 604 according to the association 600.

Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different QoS classes (as the device categories or the service requirements). For example, different QoS classes may map to different groups 604. The device 100 choses the RA preamble 508 from the group 604 that maps to the QoS class of the pending UL data and/or the QoS class of the bearer the pending UL data will be transmitted on.

Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different UE categories (as the device categories or the service requirements). For example, different UE categories may map to different groups 604 according to the association 600.

Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different subscription classes (as the device categories or the service requirements). For example, different

subscription classes may map to different groups 604 according to the association 600. The device 100 selects in the step 304 a RA preamble 508 from the group 604 that maps to the subscription class (of the user and/or the subscriber) of the radio device 508 (e.g., the UE). The subscription class of the radio device 502 may be stored in the USIM of the radio device 502.

Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different application classes (as the device categories or the service requirements). For example, this categorization can leverage an application identifier (or "App ID") assigned to each app in a digital distribution platform (such as the "App Store" or "Google Play"). Herein, the expression "app" may be an abbreviation for an application, e.g., performed by the radio device 502. To support the categorization based on the application class, the App IDs of apps (e.g., at least major apps) may be preconfigured to map to different application classes. Each such application class maps to one of the groups 604.

Optionally, there is one group 604 for all App IDs, which have not been mapped to an application class. Alternatively, individual App IDs or groups of App IDs may be configured to map to different groups 604. Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different ranges or numbers of preceding failed random access attempts (as the device categories or the service requirements). For example, different numbers (or different ranges of numbers) of preceding failed RA attempts may map to different groups 604. The device 100 selects in the step 304 a RA preamble 508 from the group 604 that maps to the number of preceding failed RA attempts the radio device 502 has performed. The RAN 504 may assign in the step 406 a higher priority to RA attempts using a RA preamble 508 from a group 604 that maps to a higher number of preceding failed RA attempts than to one using a RA preamble 508 from a group 604 that maps to a lower number of preceding failed RA attempts.

Alternatively or in addition, different groups 604 (i.e., the RA preambles 508 within the corresponding groups 604) may be associated to different transmit power levels (as the device categories or the service requirements) used for transmitting the RA preamble 508 in the step 306. For example, different ranges of random access transmit power may map to different preamble groups 604. The device 100 selects in the step 304 a RA preamble 508 from a group 604 that maps to a range including the transmit power the UE intends to use when transmitting the RA preamble 508 in the step 306, e.g., as derived from a configured transmit power derivation algorithm. Above examples of types of differentiation and categorization in terms of device categories and service requirements for defining one or more group divisions of the RA preambles 508 may be combined in the association 600. Furthermore, some or each of the groups 604 may map to a combination of categories (e.g., combinations of the above), e.g., as described with reference to Fig. 8. For example, one of the groups 604 may be used, if the pending UL data has a certain QoS class and the amount of buffered data is above a certain threshold volume or within a certain volume range.

By way of example, if the above seven non-exhaustive examples of types of differentiation are implemented, a three-bit parameter may be transmitted in the MIB, or in a SIB containing RA-related configuration data, to indicate which one of the differentiation is activated (e.g., if any) as the system information 506. Three bits can indicate 8 different values.

If more bits are used or if the number of differentiations is less than the maximum number representable by the bits, the ones not used (e.g., for the seven above examples) may be used for combinations of the types of differentiations and/or may be left for future use, i.e. for future additional types of differentiation. One of the remaining values could also be used to indicate that no preamble group division is to be applied, e.g. the value 0. Alternatively, not to apply preamble group division may be indicated by the absence of the parameter in the MIB or the SI B. Above examples for encoding the association 600 in the system information 506 are not limiting, and other examples are also feasible, such as using a single-bit parameter in the MIB or the SIB, which is indicative of whether or not to apply a single available type of differentiation (e.g., a certain group division) to the RA preambles 508 or an 8-bit parameter, which is aligned with existing octet borders in the system information 506 and/or which allows rather abundant possibilities for different types of differentiation (e.g., one or more group divisions).

The association 600, i.e., the mapping between the values of the parameter in the system information 506 (e.g., the MIB or SIB) and the types of differentiation (in terms of the device categories and service requirements) may be standardized and/or configurable, possibly with a standardized default mapping. In the latter case, the association 600, i.e., the mapping information, may be included in the (e.g., broadcasted or unicasted) system information 506, or it could be delivered to the radio device 502 in conjunction with an attach procedure. Yet other possibilities include conveying the association 600 to, or updating the association 600 at, the radio device 502 when the RRC connection is established (e.g. in the RRC Connection Setup 516 or RRC Connection Reconfiguration message). The RRC Connection Reconfiguration message may be in conjunction with a handover to another cell. Alternatively or in addition, a default association 600 may be stored on the USIM of the radio device 502.

Moreover, the number of groups 604 for the RA preamble 508 and the number of RA preambles 508 in each group 604 may be standardized or configurable (possibly with a standardized default configuration) and the ways of conveying the information to the UE could be the same as above. Preferably, such numbers and/or when to activate a group division of the RA preambles 508 are also configurable (e.g., determined by operator policies).

The different RA preambles 508 may comprise different RA sequences and/or different RA resources (e.g., physical random access channel, PRACH, resources). According to an implementation of any embodiment of the technique, the radio devices 502 may be (e.g., exclusively or additionally) differentiated through RA resources.

In addition or instead of providing the information (i.e., the device category of the radio device 502 and/or the service requirement of the radio communication) to the RAN 504 using the group division of RA preambles 508, the information (i.e., the device category of the radio device 502 and/or the service requirement of the radio communication) may be provided to the RAN 504 by letting different the device categories and/or the service requirements of the association 600 (e.g., categories of access reasons, of UEs, of users, etc.) use different PRACH resources. In other words, UL transmission resources used for the transmission of the RA preamble 508 in the step 306, e.g., different time-frequency resources in an OFDM system, are associated to the at least one of the device categories and/or the service requirements according to the association 600.

With the exception that a group division of the RA preamble 508 is replaced by group division of the RA resources, any mechanism described herein may be used. That is, the RA preamble 508 defines a RA resource (e.g., alternatively or in addition to defining a RA sequence). For example, a parameter in the MIB, or in a SIB containing RA related configuration data, may be indicative of when to apply RA resource division and/or which type of differentiation (and consequent RA resource to category mapping), i.e., the association 600, that is to be applied for determining the RA resource in the step 304. The same types of differentiation and categorization may be used.

It would also be possible to combine in the association 600 the group division by RA resources (e.g., PRACH resources) and the group division by RA sequences, thereby achieving a two-dimensional division. For example, each combination of RA resource and RA sequence (which combination may be referred to as the RA preamble 508 in the sense of the technique) may map to a different category. Alternatively, each combination of a RA resource group and a RA sequence group (which combination may be referred to as the group 604 of the RA preamble 508 in the sense of the technique) may map to a different category. For example, one or more of the service requirements 802 to 806 of Fig. 8 may be associated to different RA sequences, and one or more other service requirements 802 to 806 of Fig. 8 may be associated to different RA resources.

When using the transmit power level (as the device category and/or the service requirement) for the association 600, the size of the different groups 604 associated to different transmit power levels may be correlated. Fig. 9 schematically illustrates such a correlated association as a third example of the association 600. As a simplified example, the size of the groups 604 may be linearly related to the range achieved by the transmit power. The levels of the transmit power 904, 906 and 908 may be associated to groups 604 comprising two, three and four times the number of RA preambles 508 than the number of RA preambles 508 comprised in the group 604 associated to the level 902 of the transmit power.

As schematically illustrated in Fig. 10 for the simplified example of the association 600 that linearly relates the ranges of the transmit powers 902 to 908 and the sizes of the groups 604, the sizes of the group 604 match the sizes of the covered partial areas 1002 to 1008 of the cell or sector, respectively. In the schematic illustration of Fig. 10, an equal distribution (e.g., in the time-average) of the radio devices 502 over the covered are of the cell is assumed. In an implementation of such an association 600, the sizes of the groups 604 may further depend of the deployment (e.g., obstacles to radio propagation and topography in the cell).

The different transmit power of the RA preambles 508 for different access categories (i.e., different device categories for the radio device and/or different service requirements for the radio communication) may be used to let RA attempts pertaining to the different access categories (e.g. UE category, QoS classes, etc.) use different RA preamble transmit power algorithms. To this end, the parameters used in the algorithm for deriving the transmit power to be applied for the transmission 306 of the RA preamble, e.g., based on the received power of a downlink pilot signal transmissions (e.g., a reference signal transmissions), may have different values for different access categories. Similar as described above, different types of

differentiation may be used, each with its own categorization, with each category mapping to a set of parameter values. According to the technique, the type of differentiation to use and when to apply it is indicated in the system information, e.g., by a parameter in the MIB or in a SIB containing other configuration data related to the RA procedure.

The transmit power differentiation may apply both to the algorithm parameters for setting the transmit power of the initial RA preamble 508 and the algorithm parameters for a power ramping for subsequent RA preamble transmissions, e.g., for reattempts when no RA response 512 is received on preceding RA attempts.

In any embodiment, the association 600 may map different RA persistence settings to different access categories (i.e., different device categories for the radio device and/or different service requirements for the radio communication, e.g., including UE categories, QoS classes, pending data amounts, etc.). The different RA persistence settings may include different RA backoff timer values and/or different numbers of maximum RA attempts until the radio device 502 has to use an extended backoff timer or considers the cell as barred.

Alternatively, three or more different amounts, Vdata, of pending UL data in the radio device 502 may be differentiated by the association 600. The association 600 may further be compatible with a mapping between such service requirements (e.g., the three or more different amounts of data) and device categories (e.g., the different RA backoff timer values), as is illustrated in below Table.

Volume of pending UL data Random access backoff timer range

Vdata < VI [T4, Τ4+Δ4] (T4 > T3 > T2 > Tl)

VI≤ Vdata < V2 [T3, Τ3+Δ3] (T3 > T2 > Tl) V2≤ Vdata < V3 [Τ2, Τ2+Δ2] (T2 > T1)

V3≤ Vdata [Tl, Τ1+Δ1]

In above example, the categorization may distinguishing at least three threshold values VI, V2 and V3 for the volume of pending UL data in the radio device 502.

Alternatively or in addition, the device categories may comprise different ACB factor. That is, the association may map different access categories map to different ACB factors or barring rates.

Fig. 11 shows a schematic block diagram for an embodiment of the device 100. The device 100 comprises one or more processors 1104 for performing the method 300 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 102, 104 and 106.

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 100, such as the memory 1106, UE

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 100 being configured to perform the action.

As schematically illustrated in Fig. 11, the device 100 may be embodied by an accessing station, e.g., the radio device 502. The accessing station comprises a radio interface 1102 coupled to the device 100 for radio communication with the RAN.

Fig. 12 shows a schematic block diagram for an embodiment of the device 200. The device 200 comprises one or more processors 1204 for performing the method 400 and memory 1206 coupled to the processors 1204. For example, the memory 1206 may be encoded with instructions that implement at least one of the modules 202, 204 and 206.

The one or more processors 1204 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 1206, base station functionality. For example, the one or more processors 1204 may execute

instructions stored in the memory 1206. 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.

As schematically illustrated in Fig. 12, the device 200 may be embodied by an accessed station (e.g., a base station), e.g., of the RAN 504. The accessed station comprises a radio interface 1202 coupled to the device 200 for radio communication with one or more radio devices.

As has become apparent from above description, embodiments of the technique enable the network (e.g., the RAN and/or the CN) to take more well-founded decisions regarding acceptance or rejection of access-seeking radio devices (e.g., UEs). Same or further embodiments can enable a prioritization of the access-seeking radio devices and/or a choice of UL grant sizes.

To avoid potential negative consequences, e.g. due to possible increased random access collision probability, the technique may be dynamically turned on and off, such that it is used only when needed, e.g., depending on traffic load.

In addition, the technique may be implemented to provide the network or network operators with a wide flexibility in what aspects and/or properties to base on the differentiation of the radio devices. Moreover, these aspects and/or properties can be changed dynamically at any time.

Hence, the technique may be embodied as an efficient and flexible tool for the network to control and use its resources, as well as enforce well-founded and fair differentiation of radio devices when resources are scarce.

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

1. A method (300) of performing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the method (300) comprising or triggering the steps of:

• receiving (302), from the RAN (504), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

• transmitting (306), to the RAN (504), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

2. The method of claim 1, wherein the association (600) includes disjoint groups (604) of the RA preambles (508), and wherein the groups (604) are associated to each a different one of:

• the device categories (902, 904, 906, 908),

• the service requirements (802, 804, 806) and

• a combination of one of the device categories (902, 904, 906, 908) and one of the service requirements (802, 804, 806).

3. The method of claim 1 or 2, wherein the transmitted RA preamble (508) is indicative of the at least one of the device category (902; 904; 906; 908) of the radio device (502) and the service requirement (802; 804; 806) of the radio communication according to the association (600).

4. The method of any one of claims 1 to 3, further comprising or triggering the step of:

determining the at least one of the device category (902; 904; 906; 908) of the radio device (502) and the service requirement (802; 804; 806) of the radio communication for determining the RA preamble (508) of the transmission based on the association (600) indicated in the system information (506).

5. The method of any one of claims 1 to 4, further comprising or triggering the step of:

depending on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the transmitted RA preamble (508), selectively receiving a RA response from the RAN (504) in response to the transmitted RA preamble (508).

6. The method of any one of claims 1 to 5, further comprising or triggering the step of:

receiving from the RAN (504) in response to the transmitted RA preamble (508) a RA response that is, depending on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the transmitted RA preamble (508), selectively indicative of a rejection or a grant of radio resources of the RAN (504).

7. The method of any one of claims 1 to 6, further comprising or triggering the step of:

receiving, from the RAN (504), a RA response to the transmitted RA preamble (508), wherein the RA response is indicative of a grant of radio resources of the RAN (504), the granted radio resources depending on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the transmitted RA preamble (508).

8. The method of claim 6 or 7, wherein at least one of a size of the granted radio resources and a timing of the granted radio resources depends on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the transmitted RA preamble (508).

9. The method of any one of claims 5 to 8, wherein at least one of the selective reception of the RA response, the RA response, the selective indication in the RA response, the granted radio resources, the size of the granted radio resources and the timing of the granted radio resources further depends on the availability of resources at the RAN (504).

10. The method of any one of claims 1 to 9, wherein the service requirements (802, 804, 806) of the association (600) include bearers or types of bearers for the radio communication.

11. The method of any one of claims 1 to 10, wherein the device categories (902, 904, 906, 908) of the association (600) for the radio device (502) include at least one of Internet of Things devices, actuators, sensors, controllers, embedded devices, devices for machine-type communication, devices for ultra-reliability low-latency communication, user devices, smartphones, laptops, handheld devices, wearable devices and head-mounted displays.

12. The method of any one of claims 1 to 11, wherein the device categories (902, 904, 906, 908) of the association (600) include at least one of parameters for the RA, subscription classes and access classes.

13. The method of claim 12, wherein the parameters for the RA are indicative of at least one of a transmit power used for transmitting the RA preamble (508), a number of preceding failed RA attempts by the radio device (502) and a persistence of the RA.

14. The method of claim 13, wherein at least one of the device category (902; 904; 906; 908) of the radio device (502), the RA parameter of the radio device (502), the subscription class of the radio device (502) and the access class of the radio device (502) is stored at the radio device (502).

15. The method of any one of claims 1 to 14, wherein the service requirements (802, 804, 806) of the association (600) include at least one of application classes for an application underlying the radio communication, quality of service, QoS, requirements for the radio communication and quality of service class indicators, QCI, for the radio communication.

16. The method of any one of claims 1 to 15, further comprising or triggering the step of:

performing or initiating a service or an application at the radio device (502), wherein the service or the application triggers performing the RA.

17. The method of claims 15 and 16, wherein the service requirement (802; 804; 806) associated to the transmitted RA preamble (508) is indicative of at least one of an application class of the application, a QoS requirement of the service and a QCI of the service.

18. The method of any one of claims 1 to 17, wherein the RAN (504) includes a plurality of cells, and wherein the association (600) is related to a cell covering the radio device (502).

19. The method of any one of claims 1 to 18, wherein different radio resources are associated to different device categories (902, 904, 906, 908) for the radio device (502), to different service requirements (802, 804, 806) for the radio communication or to different combinations of device categories (902, 904, 906, 908) and service requirements (802, 804, 806), and wherein the RA preamble (508) is transmitted on one of the radio resources.

20. The method of any one of claims 1 to 19, wherein each of the RA preambles (508) corresponds to a sequence, and wherein disjoint sets of sequences are associated to different device categories (902, 904, 906, 908), different service requirements (802, 804, 806) or different combinations of one of the device categories (902, 904, 906, 908) and one of the service requirements (802, 804, 806).

21. The method of claims 4 and 20, wherein the RA preamble (508) for the transmission is determined by determining one of the sets by virtue of the

association (600), and determining the RA preamble (508) for the transmission within the determined set using a random-number generator.

22. The method of any one of claims 1 to 21, wherein the method (300) is performed by the radio device (502) in a state without uplink synchronization with the RAN (504) or without radio resources granted by the RAN (504) for uplink control signaling.

23. The method of any one of claims 1 to 22, wherein the method (300) is performed by the radio device (502) in an idle mode relative to the RAN (504).

24. A method (400) of providing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the method (400) comprising or triggering the steps of:

transmitting (402), to the radio device (502), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

receiving (404), from the radio device (502), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

The method of claim 24, further comprising or triggering the step of: determining the at least one of the device category (902; 904; 906; 908) of the radio device (502) and the service requirement (802; 804; 806) of the radio communication based on the received RA preamble (508) and the association (600) indicated in the system information (506).

26. The method of claim 24 or 25, further comprising or triggering the step of: prioritizing (406) at least one of the radio device (502) and the RA based on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the received RA preamble (508).

27. The method of any one of claims 24 to 26, further comprising or triggering the step of:

determining (406) whether to reject or respond to the received RA preamble (508) based on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the received RA preamble (508).

28. The method of claim 26 or 27, wherein the RAN (504) receives RA preambles (508) from a plurality of radio devices (502), and wherein the step (406) of prioritizing or determining is based on the device categories (902, 904, 906, 908) or the service requirements (802, 804, 806), which are associated to the received RA preambles (508) of the plurality of radio devices (502) in accordance with the association indicated in the system information.

29. The method of any one of claims 24 to 28, further comprising or triggering the step of:

depending on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the received RA preamble (508), selectively transmitting a RA response in response to the received RA preamble (508) to the radio device (502).

30. The method of any one of claims 24 to 29, further comprising or triggering the step of:

depending on the at least one of the device category (902; 904; 906; 908) and the service requirement (802; 804; 806) associated to the received RA preamble (508), selectively granting radio resources to the radio device

31. The method of any one of claims 24 to 30, further comprising or triggering any feature or step corresponding to any one of the claims 2 to 23.

32. A computer program product comprising program code portions for performing the steps of any one of the claims 1 to 31 when the computer program product is executed on one or more computing devices (1104; 1204).

33. The computer program product of claim 32, stored on a computer-readable recording medium (1106; 1206).

34. A device (100) for performing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (100) being configured to perform the steps of:

receiving, from the RAN (504), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

transmitting, to the RAN (504), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

35. The device of claim 34, further configured to perform the steps of any one of claims 2 to 23.

36. A device (200) for providing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (200) being configured to perform the step of:

transmitting, to the radio device (502), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

receiving, from the radio device (502), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

37. The device of claim 36, further configured to perform the steps of any one of claims 25 to 31.

38. A device (100) for performing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (100) comprising at least one processor (1104) and a memory (1106), said memory (1106) comprising instructions executable by said at least one processor (1104), whereby the device (100) is operative to:

receive, from the RAN (504), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

transmit, to the RAN (504), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

39. The device of claim 38, further operative to perform the steps of any one of claims 2 to 23.

40. A device (200) providing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (200) comprising at least one processor (1204) and a memory (1206), said memory (1206) comprising instructions executable by said at least one processor (1204), whereby the device (200) is operative to:

transmit, to the radio device (502), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and

receive, from the radio device (502), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

41. The device of claim 40, further operative to perform the steps of any one of claims 25 to 31.

42. A device (100) for performing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (100) comprising:

a reception unit (102) for receiving, from the RAN (504), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio communication; and a transmission unit (106) for transmitting, to the RAN (504), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

43. The device of claim 42, further comprising one or more modules for performing the steps of any one of claims 2 to 23.

44. A device (200) for providing random access, RA, to a radio access network, RAN, (504) for a radio communication involving a radio device (502), the device (200) comprising:

a transmission module (202) for transmitting, to the radio device (502), system information (506) indicative of an association (600) between RA preambles (508) for performing the RA and at least one of device categories (902, 904, 906, 908) for the radio device (502) and service requirements (802, 804, 806) for the radio

communication; and

a reception module (204) for receiving, from the radio device (502), at least one of the RA preambles (508) that is, in accordance with the association (600) indicated in the system information (506), associated to at least one of a device category (902; 904; 906; 908) of the radio device (502) and a service requirement (802; 804; 806) of the radio communication.

45. The device of claim 44, further comprising one or more modules for performing the steps of any one of claims 25 to 31.