Transmission of buffer status information

Abstract

An apparatus configured to perform: determining, in response to an amount of buffered data being available for transmission, based on receiving a configuration message specifying an association betwee

Description

TECHNICAL FIELD Various example embodiments described herein relate to the field of wireless communications. BACKGROUND Wireless communication may be configured to dynamic grant-based uplink data transmission. Resources for buffer status information transmission may be allocated based on a received scheduling request. Uplink grant for uplink data transmission may be based on the received buffer status information. Configuring contention-based resources for buffer status information in advance may remove the need for scheduling requests for sending buffer status information. Enabling transmission of limited buffer size information in case of resource collisions and / or inferior channel conditions may be beneficial. SUMMARY This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Example embodiments of the present disclosure may enable improving data transmission or reception. This benefit may be achieved by the features of the independent claims. Further example embodiments are provided in the dependent claims, the detailed description, and the drawings. According to a first aspect, an apparatus is disclosed. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, may cause the apparatus at least to perform: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, information related to the determined buffer size group. According to an example embodiment of the first aspect, the condition may be determined based on a received configuration message. According to an example embodiment of the first aspect, the received configuration message may specify a mode of transmission. According to an example embodiment of the first aspect, the mode of transmission may comprise at least one physical signal to be used for the transmitting of the information related to the determined buffer size group. According to an example embodiment of the first aspect, the received configuration message may specify an association between the plurality of buffer size groups and a plurality of physical signals. The apparatus may be further caused to perform determining a physical signal within the plurality of physical signals associated with the determined buffer size group. The apparatus may be further caused to perform the transmitting the information related to the determined buffer size group using the determined physical signal. According to an example embodiment of the first aspect, the received configuration message may specify a physical uplink shared channel resource allocated for the transmitting the information. The apparatus is further caused to perform the transmitting the information using the allocated physical uplink shared channel resource. According to an example embodiment of the first aspect, the condition may be further determined based on an application associated with the data. According to an example embodiment of the first aspect, the data may be related to a low latency service. According to an example embodiment of the first aspect, the apparatus may be further caused to perform: Determining a buffer size level within the plurality of buffer size levels associated with the amount of the buffered data. Transmitting, to the access node, information related to the determined buffer size level. According to an example embodiment of the first aspect, the apparatus may be further caused to perform the transmitting the information related to the determined buffer size group and the transmitting the information related to the determined buffer size level within one message. According to an example embodiment of the first aspect, the apparatus may be further caused to perform the transmitting the information related to the determined buffer size group and the transmitting the information related to the determined buffer size level in at least two separate messages. According to an example embodiment of the first aspect, the plurality of buffer size groups may comprise 2n predetermined buffer size groups, n being an integer. The apparatus may be further caused to perform the transmitting the information related to the determined buffer size group using an n -bit code identifying one predetermined buffer size group within the 2n predetermined buffer size groups. According to an example embodiment of the first aspect, the plurality of buffer size groups may comprise a first number of predetermined buffer size groups, the first number being an integer smaller than 2n, wherein n is an integer. The apparatus may be further caused to perform the transmitting the information related to the determined buffer size group using an n -bit code identifying one predetermined buffer size group within the first number of predetermined buffer size groups. According to an example embodiment of the first aspect, n may equal two. According to an example embodiment of the first aspect, the plurality of buffer size groups may comprise a second number of predetermined buffer size groups, the second number being an integer smaller than or equal to 2n, wherein n is a first integer, wherein the plurality of buffer size levels comprises a third number of pre-determined buffer size groups, the third number being an integer smaller than or equal to 2m, wherein m is a second integer larger than the first integer, wherein the apparatus is further caused to perform the transmitting the information related to the determined buffer size group using an n -bit code identifying one predetermined buffer size group within the second number of predetermined buffer size groups, and wherein the apparatus is further caused to perform the transmitting the information related to the determined buffer size level using an m -bit code identifying one predetermined buffer size level within the third number of predetermined buffer size levels. According to a second aspect, a method is disclosed. The method may be computer-implemented. The method may comprise: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, information related to the determined buffer size group. According to a third aspect, an apparatus is provided. The apparatus may comprise: Means for determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Means for transmitting, to an access node, information related to the determined buffer size group. According to a fourth aspect, a computer-readable medium is disclosed. The computer-readable medium may comprise program instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, information related to the determined buffer size group. According to a fifth aspect, a computer program is disclosed. The computer program may comprise instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, information related to the determined buffer size group. According to a sixth aspect, an apparatus is disclosed. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, may cause the apparatus at least to perform: Determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition may be determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Determining a demodulation reference signal configuration within the plurality of demodulation reference signal configurations associated with the determined buffer size group. Transmitting, to an access node, using the determined demodulation reference signal configuration, a first message. According to an example embodiment of the sixth aspect, the demodulation reference signal configuration may comprise at least one of: a number of demodulation reference signal symbols, a time location of the demodulation reference signal symbols, or an applied demodulation reference signal sequence. According to an example embodiment of the sixth aspect, the first message may be a demodulation reference signal message. According to an example embodiment of the sixth aspect, the apparatus may be further caused to perform: Determining a buffer size level within the plurality of buffer size levels associated with the amount of the buffered data. Transmitting, to the access node, a second message comprising information related to the determined buffer size level. According to an example embodiment of the sixth aspect, the second message may be a buffer status report medium access control control element message. According to an example embodiment of the sixth aspect, the buffer status report medium access control control element message may comprise a buffer size field identifying the determined buffer size level. According to an example embodiment of the sixth aspect, the second message may be a delay status report medium access control control element message. According to an example embodiment of the sixth aspect, the buffer status report medium access control control element message may comprise a buffer size field identifying the determined buffer size level. According to an example embodiment of the sixth aspect, the condition may be further determined based on an application associated with the data. According to an example embodiment of the sixth aspect, the data may be related to a low latency service. According to a seventh aspect, a method is disclosed. The method may be computer-implemented. The method may comprise: Determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Determining a demodulation reference signal configurations within the plurality of demodulation reference signal configurations associated with the determined buffer size group. Transmitting, to an access node, using the determined demodulation reference signal configuration, a first message. According to an eighth aspect, an apparatus is provided. The apparatus may comprise: Means for determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Means for determining a demodulation reference signal configurations within the plurality of demodulation reference signal configurations associated with the determined buffer size group. Means for transmitting, to an access node, using the determined demodulation reference signal configuration, a first message. According to a ninth aspect, a computer-readable medium is disclosed. The computer-readable medium may comprise program instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Determining a demodulation reference signal configurations within the plurality of demodulation reference signal configurations associated with the determined buffer size group. Transmitting, to an access node, using the determined demodulation reference signal configuration, a first message. According to a tenth aspect, a computer program is disclosed. The computer program may comprise instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Determining a demodulation reference signal configurations within the plurality of demodulation reference signal configurations associated with the determined buffer size group. Transmitting, to an access node, using the determined demodulation reference signal configuration, a first message. According to an eleventh aspect, an apparatus is disclosed. The apparatus may comprise at least one processor and at least one memory storing instructions that, when executed by the at least one processor, may cause the apparatus at least to perform: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, a message comprising an identification of the apparatus and information related to the determined buffer size group. According to an example embodiment of the eleventh aspect, the condition may be determined based on a received configuration message. According to an example embodiment of the eleventh aspect, the plurality of buffer size groups may comprise 2n predetermined buffer size groups, n being an integer. The message may comprise an n -bit code identifying one predetermined buffer size group within the 2n predetermined buffer size groups. According to an example embodiment of the eleventh aspect, the plurality of buffer size groups may comprise a first number of predetermined buffer size groups, the first number being an integer smaller than 2n, wherein n is an integer. The message may comprise an n -bit code identifying one predetermined buffer size group within the first number of predetermined buffer size groups. According to an example embodiment of the eleventh aspect, n may equal two. According to an example embodiment of the eleventh aspect, the message may be a buffer status report medium access control control element message. According to an example embodiment of the eleventh aspect, the buffer status report medium access control control element message may comprise a first field comprising the apparatus identification and a second field comprising the buffer size group. According to an example embodiment of the eleventh aspect, the apparatus may be further caused to perform determining a buffer size level within the plurality of buffer size levels associated with the amount of the buffered data. The message may further identify the determined buffer size level. According to an example embodiment of the eleventh aspect, the message may be a buffer status report medium access control control element. According to an example embodiment of the eleventh aspect, the buffer status report medium access control control element message may comprise a first field comprising the apparatus identification, a second field comprising the buffer size group, and a third field comprising the buffer size level. According to an example embodiment of the eleventh aspect, the plurality of buffer size groups may comprise a second number of predetermined buffer size groups, the second number being an integer smaller than or equal to 2n, wherein n is a first integer, wherein the plurality of buffer size levels comprises a third number of pre-determined buffer size groups, the third number being an integer smaller than or equal to 2m, wherein m is a second integer larger than the first integer. The message may comprise an n -bit code identifying one predetermined buffer size group within the second number of predetermined buffer size groups. The message may further comprise an m -bit code identifying one predetermined buffer size level within the third number of predetermined buffer size levels. According to an example embodiment of the eleventh aspect, the condition may be further determined based on an application associated with the data. According to an example embodiment of the eleventh aspect, the data may be related to a low latency service. According to a twelfth aspect, a method is disclosed. The method may be computer-implemented. The method may comprise: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, a message comprising an identification of the apparatus and an information related to the determined buffer size group. According to a thirteenth aspect, an apparatus is provided. The apparatus may comprise: Means for determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Means for transmitting, to an access node, a message comprising an identification of the apparatus and an information related to the determined buffer size group. According to a fourteenth aspect, a computer-readable medium is disclosed. The computer-readable medium may comprise program instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, a message comprising an identification of the apparatus and an information related to the determined buffer size group. According to a fifteenth aspect, a computer program is disclosed. The computer program may comprise instructions for causing an apparatus to perform at least the following: Determining, in response to an amount of buffered data being available for transmission, based on a condition, a buffer size group within a plurality of buffer size groups. The buffer size group may be associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Transmitting, to an access node, a message comprising an identification of the apparatus and an information related to the determined buffer size group. According to a sixteenth aspect an access node for a radio network is disclosed for communicating and / or interacting with one or more of the above aspects. The access node may comprise at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the access node at least to perform: receiving, from a user equipment, information related to a determined buffer size group, wherein the buffer size group is associated with an amount of buffered data available in the user equipment for transmission and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels, determining, in the access node, the received buffer size group using a determined demodulation reference signal configuration, and determining, in the access node, whether to use the determined buffer size group for an adequate allocation of resources for uplink transmission from the user equipment. The determination whether to use the received buffer size group information may e.g. depend on a condition, e.g. whether the access node received, in addition, more detailed buffer size level information enabling an even better matching allocation of required resources, and prioritizing the allocation of resources based on the received buffer size level over the received buffer size group information. Any example embodiment may be combined with one or more other example embodiments. Many of the attendant features will be more readily appreciated as they become better understood by reference to the following detailed description considered in connection with the accompanying drawings. DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help to understand the example embodiments. In the drawings: FIG. 1 illustrates an exemplified wireless communication system; FIG. 2 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 3 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 4 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 5 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 6 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 7 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 8 illustrates example functionalities of an apparatus according to an example embodiment; FIG. 9 illustrates a signalling diagram according to an example embodiment; FIG. 10 illustrates a signalling diagram of dynamic grant based uplink transmission; FIG. 11 illustrates an example of buffer size groups according to an example embodiment; FIG. 12 illustrates an example of buffer size groups according to an example embodiment; FIG. 13 illustrates a signalling diagram according to an example embodiment; FIG. 14 illustrates a schematic block diagram of an apparatus according to an example embodiment; and FIG. 15 illustrates a schematic block diagram of an apparatus according to an example embodiment. Like references are used to designate like parts in the accompanying drawings. DETAILED DESCRIPTION Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The detailed description provided below in connection with the appended drawings is intended as a description of the present examples and is not intended to represent the only forms in which the present example may be constructed or utilized. The description sets forth the functions of the example and the sequence of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be accomplished by different examples. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature may not apply to other embodiments. Single features of different embodiments may also be combined to provide other embodiments. Furthermore, words “comprising” and “including” should be understood as not limiting the described embodiments / examples to consist of only those features that have been mentioned and such embodiments / examples may contain also features / structures that have not been specifically mentioned. Furthermore, although the numerative terminology, such as “first”, “second”, etc., may be used herein to describe various embodiments, elements, or features, it should be understood that these embodiments, elements, or features should not be limited by this numerative terminology. This numerative terminology is used herein only to distinguish one embodiment, element, or feature from another embodiment, element, or feature. For example, a first field discussed below could be called a second field, and vice versa, without departing from the teachings of the present disclosure. In the following, different exemplifying embodiments will be described using, as an example of an access architecture to which the embodiments may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the embodiments to such an architecture, however. The embodiments may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN or E-UTRAN), long term evolution (LTE, the same as E-UTRA), wireless local area network (WiAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof. FIG. 1 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in FIG. 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in FIG. 1. The embodiments are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties. The example of FIG. 1 shows a part of an exemplifying radio access network 100. FIG. 1 shows user devices 101, 101’ configured to be in a wireless connection on one or more communication channels with a node 102. The node 102 is further connected to a core network 105. In one example, the node 102 may be an access node such as (e / g)NodeB providing or serving devices in a cell. In one example, the node 102 may be a non-3GPP access node. The physical link from a device to a (e / g)NodeB is called uplink or reverse link and the physical link from the (e / g)NodeB to the device is called downlink or forward link. It should be appreciated that (e / g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage. A communications system typically comprises more than one (e / g)NodeB in which case the (e / g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signalling purposes. The (e / g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e / g)NodeB includes or is coupled to transceivers. From the transceivers of the (e / g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e / g)NodeB is further connected to the core network 105 (CN or next generation coreNGC). Depending on the system, the counterpart on the CN side can be a serving gateway (S-GW, routing and forwarding user data packets), packet data network gateway (P-GW), for providing connectivity of user devices (UEs) to external packet data networks, or mobile management entity (MME), or access and mobility management function (AMF), etc. The user device (also called UE, user equipment, user terminal, terminal device, etc.) illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a user device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station. The user device typically refers to a device (e.g. a portable or nonportable computing device) that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and / or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction, e.g., to be used in smart power grids and connected vehicles. The user device may also utilize cloud. In some applications, a user device may comprise a user portable device with radio parts (such as a watch, earphones, eyeglasses, other wearable accessories or wearables) and the computation is carried out in the cloud. The device (or in some embodiments a layer 3 relay node) is configured to perform one or more of user equipment functionalities. The user device may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal or user equipment (UE) just to mention but a few names or apparatuses. Various techniques described herein may also be applied to a cyberphysical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. Additionally, although the apparatuses have been depicted as single entities, different units, processors and / or memory units (not all shown in FIG. 1) may be implemented. The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications). The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 106, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in FIG. 1 by “cloud” 107). The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing. The technology of Edge cloud may be brought into a radio access network (RAN) by utilizing network function virtualization (NVF) and software defined networking (SDN). Using the technology of edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes, or hosts. Application of cloud RAN architecture enables RAN real time functions being carried out at the RAN side (in a distributed unit, DU 102) and non-real time functions being carried out in a centralized manner (in a centralized unit, CU 104). It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) and 6G networks are being designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be appreciated that MEC can be applied in 4G networks as well. 5G and 6G may also utilize satellite communication to enhance or complement the coverage of 5G / 6G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, or ensuring service availability for critical communications, and future railway / maritime / aeronautical communications. Satellite communication may utilize geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). Each satellite 103 in the megaconstellation may cover several satellite-enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node 102 or by a gNB located on-ground or in a satellite. It is obvious for a person skilled in the art that the depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e / g)NodeBs, the user device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e / g)NodeBs or may be a Home(e / g)NodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometres, or smaller cells such as micro-, femto- or picocells. The (e / g)NodeBs of FIG. 1 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e / g)NodeBs are required to provide such a network structure. For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e / g)NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e / g)NodeBs, includes, in addition to Home (e / g)NodeBs (H(e / g)NodeBs), a home node B gateway, or HNB-GW (not shown in FIG. 1). A HNB Gateway (HNB-GW), which is typically installed within an operator's network may aggregate traffic from a large number of HNBs back to a core network. In 5G and 6G networks, and beyond, it is envisaged that in situations wherein buffer status report information may not be fully received and / or decoded by an access node, successfully transmitting at least a limited amount of buffer size information by a user device may be beneficial. Configuring the user device to determine a buffer size group may enable the access node to recover and / or retrieve the limited amount of buffer size information. FIG. 2 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size group. The apparatus may be a user device. Referring to FIG. 2, an amount of buffered data available for transmission is determined in operation 201. A buffer size group within a plurality of buffer size groups is determined in operation 202 in response to the amount of buffered data being available for transmission, based on a condition. The buffer size group is associated with the amount of the buffered data. The buffer size group is related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. In an example embodiment, the plurality of buffer size groups comprises 2n predetermined buffer size groups, wherein n is an integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the 2npredetermined buffer size groups. In an example embodiment, n equals two, the plurality of buffer size groups comprises four predetermined buffer size groups, and the n-bit code is a two-bit code. In an example embodiment, the plurality of buffer size groups comprises a first number of predetermined buffer size groups, the first number being an integer smaller than 2n, wherein n is an integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the first number of predetermined buffer size groups. Referring to FIG. 2, information related to the determined buffer size group is transmitted in operation 203 to an access node. In an example embodiment, the condition is determined based on a received configuration message. In an example embodiment, the received configuration message specifies a mode of transmission. In an example embodiment, the mode of transmission comprises at least one physical signal to be used for the transmitting of the information related to the buffer size group. In an example embodiment, the received configuration message specifies a type of transmission. In an example embodiment, the received configuration message specifies a physical uplink shared channel (PUSCH) resource allocated for the transmitting the information, and the transmitting the information is performed using the PUSCH resource. In an example embodiment, the condition is further determined based on an application associated with the data. In an example embodiment, the data is related to a low latency service. FIG. 3 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a physical signal associated to the buffer size group. The apparatus may be a user device. Referring to FIG. 3, the process continues from operation 202 in FIG. 2. The received configuration message specifies an association between the plurality of buffer size groups and a plurality of physical signals. A physical signal within the plurality of physical signals associated with the determined buffer size group is determined in operation 301. The information related to the determined buffer size group is transmitted in operation 302 using the determined physical signal. FIG. 4 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size level. The apparatus may be a user device. Referring to FIG. 4, the process continues from operation 202 in FIG. 2. A buffer size level within the plurality of buffer size levels associated with the amount of the buffered data is determined in operation 401. Information related to the determined buffer size level is transmitted in operation 402 to the access node. In an example embodiment, the transmitting the information related to the determined buffer size group and the transmitting the information related to the determined buffer size level are performed within one message to the access node. In an example embodiment, the transmitting the information related to the determined buffer size group and the transmitting the information related to the determined buffer size level are performed in at least two separate messages to the access node. The at least two separate messages may be part of the same transmission. In an example embodiment, the plurality of buffer size groups comprises 2” predetermined buffer size groups, wherein n is a first integer. The plurality of buffer size levels comprises 2m predetermined buffer size levels, wherein m is a second integer larger than the first integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the 2n predetermined buffer size groups. The transmitting the information related to the determined buffer size level is performed using an m-bit code identifying one predetermined buffer size level within the 2m predetermined buffer size levels. In an example embodiment, the plurality of buffer size groups comprises a second number of predetermined buffer size groups, the second number being an integer smaller than or equal to 2n, wherein n is a first integer. The plurality of buffer size levels comprises a third number of predetermined buffer size levels, the third number being an integer smaller than or equal to 2m, wherein m is a second integer larger than the first integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the second number of predetermined buffer size groups. The transmitting the information related to the determined buffer size level is performed using an m-bit code identifying one predetermined buffer size level within the third number of predetermined buffer size levels. FIG. 5 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size group. The apparatus may be a user device. Referring to FIG. 5, an amount of buffered data available for transmission is determined in operation 501. A buffer size group within a plurality of buffer size groups is determined in operation 502 in response to the amount of buffered data being available for transmission, based on a condition determined based on a received configuration message. The configuration message specifies an association between the plurality of buffer size groups and a plurality of demodulation reference signal (DMRS) configurations. The buffer size group is associated with the amount of the buffered data. The buffer size group is related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. Referring to FIG. 5, a DMRS configuration within the plurality of DMRS configurations is determined in operation 503, wherein the determined DMRS configuration is associated with the determined buffer size group. A first message is transmitted in operation 503 to an access node, using the determined DMRS configuration. In an example embodiment, the DMRS configuration comprises at least one of the following: a number of DMRS symbols, a time location of the DMRS symbols, or an applied DMRS sequence. In an example embodiment, the first message is a DMRS message. FIG. 6 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size level. The apparatus may be a user device. Referring to FIG. 6, the process continues from operation 504 in FIG. 5. A buffer size level within the plurality of buffer size levels associated with the amount of the buffered data is determined in operation 601. A second message comprising information related to the determined buffer size level is transmitted in operation 602 to the access node. In an example embodiment, the transmitting the information related to the determined buffer size group and the transmitting the information related to the determined buffer size level are performed within one message to the access node. In an example embodiment, the second message is a buffer status report (BSR) medium access control (MAC) control element (CE) message. In an example embodiment, the BSR MAC CE message comprises a buffer size field identifying the determined buffer size level. In an example embodiment, the second message is a delay status report (DSR) medium access control (MAC) control element (CE) message. In an example embodiment, the DSR MAC CE message comprises a buffer size field identifying the determined buffer size level. In an example embodiment, the condition is further determined based on an application associated with the data. In an example embodiment, the data is related to a low latency service. In an example embodiment, the first message may be transmitted jointly with the second message. In an example embodiment, a single physical uplink shared channel (PUSCH) may be used to transmit the first message and the second message. In an example embodiment, the DMRS that is used to convey the first message is used also to demodulate data bits carrying a decodable transport block including the second message as the BSR MAC CE message or the DSR MAC CE message. FIG. 7 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size group. The apparatus may be a user device. Referring to FIG. 7, an amount of buffered data available for transmission is determined in operation 701. A buffer size group within a plurality of buffer size groups is determined in operation 702 in response to the amount of buffered data being available for transmission, based on a condition. The buffer size group is associated with the amount of the buffered data. The buffer size group is related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. In an example embodiment, the condition is determined based on a received configuration message. In an example embodiment, the condition is further determined based on an application associated with the data. In an example embodiment, the data is related to a low latency service. In an example embodiment, the plurality of buffer size groups comprises 2n predetermined buffer size groups, wherein n is an integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the plurality of predetermined buffer size groups. In an example embodiment, n equals two, the plurality of buffer size groups comprises four predetermined buffer size groups, and the n-bit code is a two-bit code. In an example embodiment, the plurality of buffer size groups comprises a first number of predetermined buffer size groups, the first number being an integer smaller than 2n, wherein n is an integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the first number of predetermined buffer size groups. In an example embodiment, n equals two, the plurality of buffer size groups comprises less than four predetermined buffer size groups, and the n-bit code is a two-bit code. Referring to FIG. 7, a message comprising an identification of the apparatus and an indicator to the determined buffer size group is transmitted in operation 703 to an access node. In an example embodiment, the message is a buffer status report (BSR) medium access control (MAC) control element (CE) message. In an example embodiment, the BSR MAC CE message comprises a first field comprising the apparatus identification and a second field comprising the buffer size group. In an example embodiment, the message is a delay status report (DSR) medium access control (MAC) control element (CE) message. In an example embodiment, the DSR MAC CE message comprises a first field comprising the apparatus identification and a second field comprising the buffer size group. FIG. 8 illustrates example functionalities of an apparatus according to an example embodiment configured to determine a buffer size level. The apparatus may be a user device. Referring to FIG. 8, the process continues from operation 703 in FIG. 7. A buffer size level within the plurality of buffer size levels associated with the amount of the buffered data is determined in operation 801. The message further identifying the determined buffer size level is transmitted in operation 802. In an example embodiment, the message is a buffer status report (BSR) medium access control (MAC) control element (CE) message. In an example embodiment, the BSR MAC CE message may comprise a first field comprising the apparatus identification, a second field comprising the buffer size group, and a third field comprising the buffer size level. In an example embodiment, the message is a delay status report (DSR) medium access control (MAC) control element (CE) message. In an example embodiment, the DSR MAC CE message may comprise a first field comprising the apparatus identification, a second field comprising the buffer size group, and a third field comprising the buffer size level. In an example embodiment, the plurality of buffer size groups comprises 2n predetermined buffer size groups, wherein n is a first integer. The plurality of buffer size levels comprises 2m predetermined buffer size levels, wherein m is a second integer larger than the first integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the 2n predetermined buffer size groups. The transmitting the information related to the determined buffer size level is performed using an m-bit code identifying one predetermined buffer size level within the 2m predetermined buffer size levels. In an example embodiment, n equals two. In an example embodiment, the plurality of buffer size groups comprises a second number of predetermined buffer size groups, the second number being an integer smaller than or equal to 2n, wherein n is a first integer. The plurality of buffer size levels comprises a third number of predetermined buffer size levels, the third number being an integer smaller than or equal to 2m, wherein m is a second integer larger than the first integer. The transmitting the information related to the determined buffer size group is performed using an n-bit code identifying one predetermined buffer size group within the second number of predetermined buffer size groups. The transmitting the information related to the determined buffer size level is performed using an m-bit code identifying one predetermined buffer size level within the third number of predetermined buffer size levels. In an example embodiment, n equals two. FIG. 9 illustrates a signalling diagram according to an example of information exchange in a communication network configured to enable contention-based buffer status information transmission. The term “UE” is used for a user device configured to determine buffer size group information. The term “AN” is used for an access node. The access node may be, e.g., a gNB or a distributed access node, comprising for example a centralized unit (CU) and a distributed unit (DU) enabling RAN real time functions being carried out at the RAN side (in the DU) and non-real time functions being carried out in a centralized manner (in the CU). The UE is assumed to be in a connected mode operation and an initial access with system information is assumed to have been obtained successfully from the AN or the network. The term “message” is used for, e.g., a downlink control information (DCI), a medium access control (MAC) control element (CE), or an information element. Referring to FIG. 9, the AN 401 transmits (message 9-1) a configuration message for contention-based buffer size information transmission to the UE 101. The UE determines in block 9-2 whether there is buffered data available for transmission. If there is an amount of buffered data available, the UE determines in block 9-3 a buffer size group within a plurality of buffer size groups. The buffer size group is associated with the amount of buffered data. The buffer size group is related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. The UE transmits (message 9-4) a message comprising information related to the determined buffer size group to the AN. In an example embodiment, the message is transmitted using a DMRS configuration. The same transmission may also contain a BSR MAC CE or DSR MAC CE. Then if decoding of the transmitted information by the AN fails, the AN does not have the BSR or DSR, but it can still use the buffer size group information obtained from the DMRS. Thus, the AN may be able to retrieve in block 9-5 the information related to the determined buffer size group even though the AN may not be able to fully decode the message. The AN transmits (message 9-6) a message granting uplink resources for transmission to the UE, and the UE transmits (message 9-7) the buffered data to the AN using the granted resources. FIG. 10 illustrates an example signalling diagram of dynamic grant based UL data transmission. The term “UE” is used for a user device. The term “AN” is used for an access node. The access node may be, e.g., a gNB or a distributed access node, comprising for example a centralized unit (CU) and a distributed unit (DU) enabling RAN real time functions being carried out at the RAN side (in the DU) and non-real time functions being carried out in a centralized manner (in the CU). Referring to FIG. 10, in step 10-1, SR is triggered in a periodic manner or when there is the UL data coming to UE buffer. In step 10-2, when UL SR is received, the AN allocates an UL resource for BSR transmission. In step 10-3, the UE sends a buffer status report with the allocated resource. Additionally, the UE may also send UL data (assuming the allocated resource is larger than the resource needed for BSR transmission). In step 10-4, based on the received BSR, the AN determines size of UL grant and sends an UL grant for UL data transmission. In step 10-5, the UE sends UL data with the granted resource. As shown in FIG. 10, the BSR is transmitted with UL grant after receiving UL grant from the AN. Additionally, padding BSR can be sent as well when the UE already has the UL resource. In case the AN cannot fully decode the BSR which is carried in the contention based UL PUSCH, the AN may still obtain certain or limited UE buffer information. Even with limited information, the AN could allocate UL dedicated resource to the UE which may be already sufficient for the UE. Obtaining the information may be realised by an enhanced contention-based BSR transmission on PUSCH. If the resource used for UL BSR transmission is configured beforehand, contention-based BSR transmission can result in reduced latency comparing to the normal procedure shown in FIG 10. Part 10-6 of FIG. 10, that is, steps 10-1 and 10-2 for SR transmission and waiting for UL grant for BSR transmission may then be removed from the signalling diagram. Contention-based BSR may be supported with existing standards by configuration if the UE is, e.g., configured with CG PUSCH resources for the transmission of BSR in the format of MAC CE, and the AN configures the same frequency and time resources to two or more UEs. The UE may use one or more PHY signals of PUSCH containing the BSR to carry limited or certain information about UE buffer status. Information carried over PHY signalling may include buffer size group information and a UE ID. Using for example DMRS to carry UE ID information is known from, e.g., contention based CG PUSCH transmission (in case of a common resource for multiple UEs) or MU-MIMO. The buffer status information may be, e.g., BSR table information (e.g., 5-bit or 8-bit BSR table) and / or a buffer status indicator, e.g., buffer size values in a BSR table may be grouped into multiple groups and a corresponding buffer size group index may be used as a buffer status indicator. A RRC configuration can be used to configure certain information to the UE, such as, e.g., a UE dedicated PHY signal resource (in time / frequency / spatial / code or the combination) to indicate UE ID information, PHY signal resources (in time / frequency / spatial / code or the combination) to indicate certain BSR information, (e.g. a set of resources to indicate buffer size group index by resource selection), or buffer size group information (e.g. how to divide the BSR table(s) into multiple groups). Configuring the transmission of buffer size group information may be performed, e.g., together with RRC configuration or as an additional activation step after RRC configuration. In order for the AN to get certain UE and BSR information also when the CB PUSCH containing the BSR is not decoded fully or correctly due to, e.g., a collision, deep channel fading, or other reasons, the AN may configure the UE with necessary information for a CB PUSCH transmission. Resources for delivery of UE ID information may comprise that different DMRS resources are configured to different UEs, so that the AN can identify UE based on the resources on which a DMRS signal is detected. The different DMRS resources may be different DMRS sequences, different DMRS antenna ports, or DMRS over different symbols within a slot (e.g., one UE sending DMRS over symbol#0 and #7, and another UE sending the same DMRS sequences over symbol #1 and #8) and certainly different DMRS resource combination. For example, one or more dedicated DMRS sequences may be allocated to one UE. Then the AN can know the UE ID information based on the detected one or more DMRS sequences. The different DMRS antenna ports refer to the way DMRS sequence is, e.g., in 5GNR mapped to resource elements and spread with orthogonal cover code in frequency and / or in time. The mapping and spreading may depend on antenna port index and may provide DMRS signals that are mutually orthogonal. Resources for delivery of buffer size group index may comprise that different DMRS resources may be configured for different buffer size group indexes, so that the AN may identify the buffer size group index based on the resources on which DMRS signal is detected. The different DMRS resources may be different DMRS sequences or different DMRS antenna ports. The different DMRS sequences may be allocated to different DMRS symbols or to different parts of the allocated frequency resources, e.g., such that there may be one symbol / one part of the frequency resource that will use one sequence, and another symbol or symbols that may use a different sequence or sequences, depending on the information to be conveyed. The UE may determine that a triggering condition for BSR transmission on CB PUSCH is fulfilled and then select the DMRS resource(s) used in the CB PUSCH transmission based on the received configuration as well as the reported BSR. The AN may monitor CB PUSCH occasions for PUSCH transmission and try to decode PUSCH transport block (TB). In case PUSCH TB decoding fails while the presence of DMRS sequence(s) is detected, the AN may determine UE ID(s) of possibly transmitting UE(s) as well as corresponding limited BSR information and utilize that in further UL scheduling. The AN may need to run a DMRS sequence detection procedure with possible DMRS sequence hypotheses first to identify which DMRS sequences the UE is using. After this procedure the limited BSR information may be known to the AN. After determining actually used DMRS sequences the channel estimate is formed from the now known DMRS sequences, the PUSCH demodulation may be done, and TB decoding may be attempted. Buffer size grouping information may comprise different BSR tables defined. In order to help the AN to determine the amount of UL resources, two types of information may be needed: (1) BSR table information (i.e. which BSR table is selected by the UE) and (2) buffer size group selected by the UE based on the amount of UL data to be transmitted. Depending on the deployment scenario and UE types / capabilities (e.g. XR devices, loT devices), it may also be possible that the information about BSR table is not needed since one table may be sufficient. Multiple BSR tables may also be used in the BSR reporting on UL-SCH, while the limited BSR information carried on PHY signals is determined based on a single BSR grouping, e.g., based on 5-bit buffer size values, or separately from the buffer size values used for actual BSR reporting. Two examples of configured buffer size groups are shown in FIG. 11 and FIG. 12, respectively. FIG. 11 shows an example of buffer size groups with a 5-bit buffer size field. FIG. 12 shows an example of buffer size groups with an 8-bit buffer size field. Fig. 11 shows a BSR table with additional buffer size group info. In case of a BSR, there may be one or multiple BSR tables, but the buffer size group info carried over a DMRS may be independent from the BSR table. For example, in general, and / or related to tables of FIG. 11 and FIG. 12, the buffer size group info may be encoded using two bits as follows: - “00” in case the buffer size is larger than 0 but smaller than or equal to threshold #1, e.g., in FIG. 11 threshold #1 is exemplarily determined or selected to be 276 (buffer size value of buffer size level), and in FIG. 12 threshold #1 is exemplarily determined or selected to be 384; - “01” in case the buffer size larger than threshold #1 but smaller than or equal to threshold #2, e.g., in FIG. 11 threshold #2 is exemplarily determined or selected to be 14726 (buffer size value of buffer size level), and in FIG. 12 threshold #2 is exemplarily determined or selected to be 18951; - “10” in case the buffer size larger than threshold #2 but smaller than or equal to threshold #3, e.g., in FIG. 11 threshold #3 is exemplarily determined or selected to be 150000 (buffer size value of buffer size level), and in FIG. 12 threshold #3 is exemplarily determined or selected to be 1452903; - “11” in case the buffer size is larger than threshold #3 and potentially lower than a threshold #4. Such two-bit coding for one or more buffer size groups shows that instead of or in addition to a five-bit or eight-bit coding for the buffer size level, a new type of coding being shorter in bits and thus less vulnerable to interferences and collisions is introduced, enabling the AN to get certain buffer status report info even in case the normal BSR is corrupted. In general, n bits may be used to encode buffer size group information compared to m bits for encoding buffer size level info with n <m, wherein n is an integer larger or equal to one, that is, n = 1, 2, 3, ..., and m is an integer larger than n, that is, m = 2, 3, 4, ... . This new buffer size group info (e.g., additional, less detailed buffer size info) may be transmitted in and / or encoded into different ways, e.g., using physical signals like DMRS (indirect hint to group info) or directly (e.g. as 2 extra bits added to the normal BSR). Potential transmission options include, e.g., new buffer size group info transmitted in a separate message, together with normal BSR or DSR, using DMRS, in CB PUSCH scenario, etc. A BSR may include an ordering of information transmission, e.g., including first UE ID, then buffer size group info, and then buffer size level info. In case of collision (e.g. partly overlapping signals from different UEs) and, e.g., in case buffer size level info is not detectable or decodable, then there may still be a high probability that the buffer size group info is still detectable, and a subsequent adequate allocation of (fitting) resources for uplink transmission from UE to network can be performed by the network. In an example embodiment, the AN may configure one or multiple DMRS antenna ports for a single UE for single layer PUSCH transmission. When multiple antenna ports are configured together with two DMRS symbols, the UE may use one predefined DMRS antenna port at first DMRS symbol(s), which may be utilized for UE identification (in case that PUSCH detection fails). The UE may select (from the set of configured DMRS antenna ports) a DMRS antenna port at second DMRS symbol(s) for limited buffer status indication, i.e., a buffer size group index. Multiple UEs may be configured with same or partially overlapping sets of DMRS antenna ports for buffer size group indication. In case of collision, the AN may detect multiple UE identifiers as well as multiple buffer size group indexes. The AN may not know which buffer size group index is transmitted by which UE. In such a case, based on the detected buffer size group indexes, the AN may determine largest buffer size group index possible for each detected UE. As an example of partially overlapping configuration of DMRS antenna ports, if there are only two buffer size groups, such as, e.g., a low buffer size and a high buffer size, the AN may configure four antenna ports in total for a CB PUSCH resource shared by three UEs (UEs #l-#3). A separate DMRS antenna port may be configured for each UE for a first DMRS symbol. For a second DMRS symbol, DMRS antenna port #0 may be configured as a low buffer size indicator for all UEs, and DMRS antenna ports #1, #2, #3 may be configured for UEs #1, #2, #3, respectively, as high buffer size indicators. If a single antenna port is configured per UE, the AN may allocate different DMRS antenna ports to different UEs sharing same resource (for contention based access) and use that for UE identification. In the above discussion, DMRS has been used as an example to describe how the proposed concept work. In principle other signals, e.g., scrambling sequences or other PHY signal may be used as well. Also, the concept may be implemented for other status report information than BSR or DSR. With multiple sequences configured to one UE, an increased number of sequences may be needed in order to support a large number of UEs. Such impact may be controlled by the AN, e.g., by configuring such operation only for selected UEs which are vulnerable to the contention based access such as, e.g., UEs with bad channel conditions, UEs with reduced TX power, or UEs with latency critical DRBs. FIG. 13 illustrates a signalling diagram according to an example of information exchange in a communication network configured to enable contention-based buffer status information transmission. The term “UE” is used for a user device configured to determine buffer size group information. The term “AN” is used for an access node. The access node may be, e.g., a gNB or a distributed access node, comprising for example a centralized unit (CU) and a distributed unit (DU) enabling RAN real time functions being carried out at the RAN side (in the DU) and non-real time functions being carried out in a centralized manner (in the CU). The UE is assumed to be in a connected mode operation and an initial access with system information is assumed to have been obtained successfully from the AN or the network. The term “message” is used for, e.g., a downlink control information (DCI), a medium access control (MAC) control element (CE), or an information element. Referring to FIG. 13, the AN transmits (message 13-1) a configuration message for contention-based buffer size information transmission to the UE. The configuration may comprise necessary information for carrying UE ID information and buffer size group information. The UE determines in block 13-2 whether there is buffered data available for transmission and the condition for BSR transmission. If there is an amount of buffered data available, the UE determines in block 13-3 a buffer size group within a plurality of buffer size groups. The buffer size group is associated with the amount of buffered data. The buffer size group is related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels. The UE transmits (message 13-4) a BSR message comprising information related to the determined buffer size group to the AN over contentionbased PUSCH. In an example embodiment, the message is transmitted using a DMRS configuration. The same transmission may also contain a BSR MAC-CE. Then if decoding of the transmitted information by the AN fails, the AN does not have the BSR, but it can still use the buffer size group obtained from the DMRS. Thus, the AN determines in block 13-5 that the BSR is not fully decoded but is able to retrieve in block 13-6 the UE ID and the information related to the determined buffer size group based on the detected physical signalling. The AN transmits (message 13-7) a message granting uplink resources for transmission based on the detected PHY information to the UE, and the UE transmits (message 13-8) the buffered data to the AN using the granted resources. The message may comprise a padding BSR to request additional resources. FIG. 14 illustrates an example embodiment of an apparatus 1400, which may be an apparatus such as, or comprised in, a user device. The apparatus 1400 may correspond to any of the user devices 101, 101’ of FIG. 1. The apparatus may also be called a subscriber unit, mobile station, remote terminal, access terminal, user terminal, terminal device, user equipment (UE), vehicle, or any electric device. Although the apparatus 1400 is illustrated as a single device, it is appreciated that, wherever applicable, functions of the apparatus 1400 may be distributed to a plurality of devices. The apparatus 1400 may comprise at least one processor 1402. The at least one processor 1402 may comprise, for example, one or more of various processing devices or processor circuitry, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. The apparatus 1400 may further comprise at least one memory 1404. The at least one memory 1404 may be configured to store, for example, computer program code or the like, for example operating system software and application software. The at least one memory 1404 may comprise one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination thereof. For example, the at least one memory 1404 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.). The apparatus 1400 may further comprise a communication interface 608 configured to enable the apparatus 1400 to transmit and / or receive information to / from other devices. In one example, the apparatus 1400 may use the communication interface 1408 to transmit or receive signalling information and data in accordance with at least one data communication or cellular communication protocol. The communication interface 1408 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connections may be also implemented as separate communication interfaces, which may be coupled or configured to be coupled to one or more of a plurality of antennas. The communication interface 1408 may comprise a receiver, a transmitter, or a transceiver. FIG. 15 illustrates an example embodiment of an apparatus 1500, which may be an apparatus such as, or comprised in, an access node. The apparatus 1500 may correspond to the access node 102 of FIG. 1 such as (e / g)NodeB or any access node, or in general a device configured to implement the functionalities or some of the functionalities described herein. Although the apparatus 1500 is illustrated as a single device, it is appreciated that, wherever applicable, functions of the apparatus 1500 may be distributed to a plurality of devices. The apparatus 1500 may comprise at least one processor 1502. The at least one processor 1502 may comprise, for example, one or more of various processing devices or processor circuitry, such as for example a co-processor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuitry with or without an accompanying DSP, or various other processing devices including integrated circuits such as, for example, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a microcontroller unit (MCU), a hardware accelerator, a special-purpose computer chip, or the like. The apparatus 1500 may further comprise at least one memory 1504. The at least one memory 1504 may be configured to store, for example, computer program code or the like, for example operating system software and application software. The at least one memory 1504 may comprise one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination thereof. For example, the at least one memory 1504 may be embodied as magnetic storage devices (such as hard disk drives, floppy disks, magnetic tapes, etc.), optical magnetic storage devices, or semiconductor memories (such as mask ROM, PROM (programmable ROM), EPROM (erasable PROM), flash ROM, RAM (random access memory), etc.). The apparatus 1500 may further comprise a communication interface 1508 configured to enable the apparatus 1500 to transmit and / or receive information to / from other devices. In one example, the apparatus 1500 may use the communication interface 1508 to transmit or receive signalling information and data in accordance with at least one data communication or cellular communication protocol. The communication interface 1508 may be configured to provide at least one wireless radio connection, such as, for example, a 3GPP mobile broadband connection (e.g., 3G, 4G, 5G, 6G etc.). The communication interface 1508 may comprise, or be configured to be coupled to, at least one antenna to transmit and / or receive radio frequency signals. One or more of the various types of connections may be also implemented as separate communication interfaces, which may be coupled or configured to be coupled to one or more of a plurality of antennas. The communication interface 1508 may comprise a receiver, a transmitter, or a transceiver. Referring to FIG. 14 and FIG. 15, when the apparatus 1400, 1500 is configured to implement some functionality, some component and / or components of the apparatus 1400, 1500, such as for example the at least one processor 1402, 1502 and / or the at least one memory 1404, 1504, may be configured to implement this functionality. Furthermore, when the at least one processor 1402, 1502 is configured to implement some functionality, this functionality may be implemented using program code 1406, 1506 comprised, for example, in the at least one memory 1404, 1504. The functionality described herein may be performed, at least in part, by one or more computer program product components such as for example software components. According to an example embodiment, the apparatus 1400, 1500 may comprise a processor or processor circuitry, such as for example a microcontroller, configured by the program code when executed to execute the embodiments of the operations and functionality described. The program code 1406, 1506 is provided as an example of instructions which, when executed by the at least one processor 1402, 1502, cause performance of apparatus. Alternatively, or additionally, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), application-specific Integrated Circuits (ASICs), application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), Graphics Processing Units (GPUs). The apparatus 1400, 1500 may be configured to perform or cause performance of any aspect of the method(s) described herein. Further, a computer program may comprise instructions for causing, when executed, an apparatus to perform any aspect of the method(s) described herein. The computer program may be stored on a computer-readable medium. Further, the apparatus 1400, 1500 may comprise means for performing any aspect of the method(s) described herein. In one example, the means may comprise the at least one processor 1402, 1502, the at least one memory 1404, 1504 including the program code 1406, 1506 (instructions) configured to, when executed by the at least one processor 1402, 1502, cause the apparatus 1400, 1500 to perform the method(s). In general, computer program instructions may be executed on means providing generic processing functions. The method(s) may be thus computer-implemented, for example, algorithm(s) executable by the generic processing functions, an example of which is the at least one processor 1402, 1502. The means may comprise transmission and / or reception means, for example one or more radio transmitters or receivers, which may be coupled or be configured to be coupled to one or more antennas, or transmitters) or receiver(s) of a wired communication interface. As used in this application, the term ‘circuitry’ refers to all of the following: (a) hardware-only circuit implementations, such as implementations in only analogue and / or digital circuitry, and (b) combinations of circuits and software (and / or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s) / software including digital signal processor(s), software, and memory(ies) that work together to cause an apparatus to perform various functions, and (r) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. This definition of ‘circuitry’ applies to all uses of this term in this application. As a further example, as used in this application, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile device or a similar integrated circuit in a sensor, a cellular network device, or another network device. Although the subject matter has been described in language specific to structural features and / or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example embodiments of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims. It will be understood that the benefits and advantages described above may relate to one example embodiment or may relate to several example embodiments. The example embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. It will further be understood that reference to 'an' item may refer to one or more of those items. The steps or operations of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate Additionally, individual blocks may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the example embodiments described above may be combined with aspects of any of the other example embodiments described to form further example embodiments without losing the effect sought. It will be understood that the above description is given by way of example embodiments only and that various modifications may be made by those skilled in the art. The above specification, example embodiments and data provide a complete description of the structure and use of exemplary embodiments. Although various example embodiments have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed example embodiments without departing from scope of this specification. LIST OF ABBREVIATIONS BSR Buffer Status Report CB Contention Based CG Configured Grant DCI Downlink Control Information DL Downlink DMRS Demodulation Reference Signal DRB Data Radio Bearer DSR Delay Status Report LCH Logical Channel LCID Logical Channel Identifier MAC Medium Access Control MAC CE MAC Control Element NR New Radio PDCCH Physical Downlink Control Channel PHY Physical layer PUSCH Physical Uplink Shared Channel RRC Radio Resource Control SR Scheduling Request UCI Uplink Control Information UE User Equipment UL Uplink

Claims

1. An apparatus comprising:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform:determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels;determining a demodulation reference signal configuration within the plurality of demodulation reference signal configurations associated with the determined buffer size group; andtransmitting, to an access node, using the determined demodulation reference signal configuration, a first message.

2. An apparatus according to claim 1, wherein the demodulation reference signal configuration comprises at least one of: a number of demodulation reference signal symbols, a time location of the demodulation reference signal symbols, or an applied demodulation reference signal sequence.

3. An apparatus according to claim 1 or 2, wherein the first message is a demodulation reference signal message.

4. An apparatus according to any of the preceding claims, wherein the apparatus is further caused to perform:determining a buffer size level within the plurality of buffer size levels associated with the amount of the buffered data; andtransmitting, to the access node, a second message comprising information related to the determined buffer size level.

5. An apparatus according to claim 4, wherein the second message is a buffer status report medium access control control element message.

6. An apparatus according to claim 5, wherein the buffer status report medium access control control element message comprises a buffer size field identifying the determined buffer size level.

7. An apparatus according to claim 4, wherein the second message is a delay status report medium access control control element message.

8. An apparatus according to claim 7, wherein the buffer status report medium access control control element message comprises a buffer size field identifying the determined buffer size level.

9. An apparatus according to any of the preceding claims, wherein the condition is further determined based on an application associated with the data.

10. An apparatus according to claim 9, wherein the data is related to a low latency service.

11. A method comprising:determining, in response to an amount of buffered data being available for transmission, based on a condition, wherein the condition is determined based on a received configuration message specifying an association between a plurality of buffer size groups and a plurality of demodulation reference signal configurations, a buffer size group within the plurality of buffer size groups, wherein the buffer size group is associated with the amount of the buffered data and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels;determining a demodulation reference signal configurations within the plurality of demodulation reference signal configurations associated with the determined buffer size group; andtransmitting, to an access node, using the determined demodulation reference signal configuration, a first message.

12. A computer-readable medium comprising program instructions for causing an apparatus to perform the steps of the method of claim 11.

13. An access node for a radio access network, wherein the access node comprises:at least one processor; andat least one memory storing instructions that, when executed by the at least one processor, cause the access node at least to perform:receiving, from a user equipment, information related to a determined buffer size group, wherein the buffer size group is associated with an amount of buffered data available in the user equipment for transmission and related to a buffer size value range covering at least two buffer size levels within a plurality of buffer size levels,determining, in the access node, the received buffer size group using a determined demodulation reference signal configuration, anddetermining, in the access node, whether to use the determined buffer size group for an adequate allocation of resources for uplink transmission from the user equipment.

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