TECHNICAL FIELD

Embodiments presented herein relate to a method, a client node, a computer program, and a computer program product for handling group

communication in a wireless communication system.

BACKGROUND

In communications systems, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications system is deployed.

An example of applications available in some communications system is group communications services. In general terms, group communication means that the same information or media is delivered to multiple client nodes. In group communication systems the client nodes receiving the same media constitute a group of client nodes. These client nodes may be located at different locations in a radio coverage area served by one or more radio access network nodes. If many client nodes are located within the same area, the one or more radio access network nodes could use multicast or broadcast based transmission using e.g., Multicast-Broadcast Multimedia Services (MBMS) for efficient communication to the group of client nodes since communications resources, such as time and frequency resources, are shared among the client nodes.

MBMS provides a one-way communication channel, meaning that the data is broadcasted from a radio access network node towards all wireless devices. When a wireless device that receives data over an MBMS bearer is moving closer to the border of the radio coverage area served by the radio access network node, the wireless device will request to receive the group

communication data over a unicast bearer instead of as before via broadcast. At the edge of the border of the radio coverage area a unicast bearer will typically have better coverage compared to an MBMS bearer. A unicast bearer provides means for the wireless device to request link adaptation,

retransmission etc. to reach an acceptable packet loss rate. An example of transferring group communication from an MBMS bearer to a unicast bearer due to poor broadcast reception conditions is given in Section 10.10.5 and Figure 10.10.5-1 in 3GPP TS 23.179 V13.3.0 "Functional architecture and information flows to support mission critical communication services; Stage 2". Since transmission using a unicast bearer in some situations, such as a the edge of the border of the radio coverage area, consumes more network resources than broadcast transmission, using a unicast bearer could be costly from a network resource perspective.

Hence, there is still a need for improved mechanism for handling group communication for wireless devices.

SUMMARY

An object of embodiments herein is to provide efficient handling of group communication for wireless devices.

According to a first aspect there is presented a method for handling group communication. The method is performed by a client node. The client node is hosted by a host wireless device. The method comprises determining that signal quality of broadcast group communication received from a radio access network node is below a signal quality threshold for reliable broadcast communication. The method comprises attempting discovery of a relay wireless device for acting as group communication relay between the radio access network node and the host wireless device. The method comprises initiating, when the relay wireless device is discovered, a connection between the host wireless device and the relay wireless device in order for the relay wireless device to act as relay for the group communication from the radio access network node to the client node. Advantageously this method provides efficient handling of group

communication for wireless devices, especially for wireless devices close to coverage area borders.

Advantageously, by using this method a transfer of the broadcast group communication to a unicast bearer, which in the described scenario is costly from a network resource utilization perspective, is avoided.

Advantageously, by using this method packet loss is reduced compared to current methods handling of group communication since the herein presented method triggers the transfer before the wireless device is reaching the cell border.

According to a second aspect there is presented a client node for handling group communication. The client node comprises processing circuitry. The client node is configured to be hosted by a host wireless device. The processing circuitry is configured to cause the client node to determine that signal quality of broadcast group communication received from a radio access network node is below a signal quality threshold for reliable broadcast communication. The processing circuitry is configured to cause the client node to attempt to discover a relay wireless device for acting as group communication relay between the radio access network node and the host wireless device. The processing circuitry is configured to cause the client node to initiate, when the relay wireless device is discovered, a connection between the host wireless device and the relay wireless device in order for the relay wireless device to act as relay for the group communication from the radio access network node to the client node. According to a third aspect there is presented a client node for handling group communication. The client node comprises processing circuitry and a storage medium. The client node is configured to be hosted by a host wireless device. The storage medium stores instructions that, when executed by the processing circuitry, causes the client node to perform operations, or steps. The operations, or steps, cause the client node to determine that signal quality of broadcast group communication received from a radio access network node is below a signal quality threshold for reliable broadcast communication. The operations, or steps, cause the client node to attempt to discover a relay wireless device for acting as group communication relay between the radio access network node and the host wireless device. The operations, or steps, cause the client node to initiate, when the relay wireless device is discovered, a connection between the host wireless device and the relay wireless device in order for the relay wireless device to act as relay for the group communication from the radio access network node to the client node.

According to a fourth aspect there is presented a client node for handling group communication. The client node is configured to be hosted by a host wireless device. The client node comprises a determine module configured to determine that signal quality of broadcast group communication received from a radio access network node is below a signal quality threshold for reliable broadcast communication. The client node comprises a discover module configured to attempt to discover a relay wireless device for acting as group communication relay between the radio access network node and the host wireless device. The client node comprises an initiate module configured to initiate, when the relay wireless device is discovered, a connection between the host wireless device and the relay wireless device in order for the relay wireless device to act as relay for the group communication from the radio access network node to the client node.

According to a fifth aspect there is presented a computer program for handling group communication, the computer program comprising computer program code which, when run on a client node hosted by a host wireless device, causes the client node to perform a method according to the first aspect.

According to a sixth aspect there is presented a computer program product comprising a computer program according to the fifth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

It is to be noted that any feature of the first, second, third, fourth, fifth and sixth aspects may be applied to any other aspect, wherever appropriate.

Likewise, any advantage of the first aspect may equally apply to the second, third, fourth, fifth and/or sixth aspect, respectively, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings. Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which: Figs. 1 and 2 are schematic diagram illustrating communications systems according to embodiments;

Figs. 3 and 4 are flowcharts of methods according to embodiments;

Fig. 5 is a signalling diagram according to an embodiment;

Fig. 6 is a schematic diagram showing functional units of a client node according to an embodiment;

Fig. 7 is a schematic diagram showing functional modules of a client node according to an embodiment; and Fig. 8 shows one example of a computer program product comprising computer readable storage medium according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

Figs, l and 2 are schematic diagrams illustrating communications systems looa, loob where embodiments presented herein can be applied. The communications systems 100a, 100b are assumed to provide services for group communication and may hence be regarded as group communications systems. The group communications systems 100a, 100b are, according to some aspects, a push to talk (PTT) system. The group communication could thus comprise a push to talk service. The communications systems 100a, 100b comprise a radio access network (as represented by its radio coverage area 120), a core network 140, and a service network 150. The communications systems 100a, 100b further comprises at least one control node 300 and at least one client node 200a, 200b, 200c. Each client node 200a, 200b, 200c could be a mission critical (MC) service client. The at least one control node 300 may be provided in, or installed on, at least one radio access network (RAN) node 110a, 110b or in another entity or device in the radio access network, in an entity or device of the core network 140, or in an entity or device of the service network 150. The at least one control node 300 could implement the functionality of a group

communication application server (GCS AS) and be a MC service server. Each client node 200a, 200b, 200c may be hosted by, provided in, or installed on, a respective wireless device 160a, 160b, 160c.

The radio access network is operatively connected to the core network 140 which in turn is operatively connected to the service network 150. The at least one radio access network node 110a, 110b thereby enables the wireless devices 160a, 160b, 160c, and hence the client nodes 200a, 200b, 200c, to access services and exchange data as provided by the service network 150.

Examples of wireless devices 160a, 160b, 160c include, but are not limited to, mobile stations, mobile phones, handsets, wireless local loop phones, user equipment (UE), smartphones, laptop computers, and tablet computers. Examples of radio access network nodes 110a, 110b include, but are not limited to, radio base stations, base transceiver stations, node Bs, evolved node Bs, and access points. As the skilled person understands, the

communications systems 100a, 100b may comprise a plurality of radio access network nodes 110a, 110b (as illustrated by a single radio access network node 110a in Fig. 1 and two radio access network nodes 110a, 110b in Fig. 2), each providing network access to a plurality of wireless devices 160a, 160b, 160c. The herein disclosed embodiments are not limited to any particular number of radio access network nodes 110a, 110b, client nodes 200a, 200b, 200c, or wireless devices 160a, 160b, 160c. In this respect Fig. 1 illustrates a single cell MBMS broadcast area and Fig. 2 illustrates multiple cells contributing to the same MBMS bearer, typically known as an MBMS signal frequency network (MBSFN). That is, the communications system 100b could be a MBSFN. Hence, the radio access network node 110a, 110b could be part of a MBSFN.

As disclosed above, in a group communication system (e.g. a PTT system) it is common to use a broadcast technology such as MBMS. Using MBMS allows group communication data to be broadcasted while the wireless devices 160a, 160b, 160c are in idle mode, i.e. only listening to the broadcasted data. The area 130, 130' inside the radio coverage area 120 represents the radio coverage area where the wireless devices 160a, 160b, 160c are able to receive broadcasted group communication data as transmitted by the radio access network nodes iioa, nob using (uni-directional) broadcast, such as MBMS. At the edge of the area 130, 130' there will be locations where unicast coverage is better and where the radio coverage area 120 will extend beyond the area 130, 130'. The reason for this is that when (bi-directional) unicast communication (requiring a unicast bearer) is used there are different technologies that can be applied to improve the radio quality, such as link adaption, transmission time interval (TTI) bundling, retransmission etc.

Figs. 1 and 2 further illustrates schematic connections 170, 180, 190 on which group communication is provided from the radio access network node 110a to the wireless device 160a; a direction connection 170 is between the radio access network node 110a and the wireless device 160a, and an indirection connection has a first connection part 180 between the radio access network node 110a and the wireless device 160b, and a second connection part 190 between the wireless device 160b and the wireless device 160a.

Assume for illustrative purposes that wireless device 160a listens to broadcast group communication (via connection 170) and moves outside the area 130, 130', as illustrated by arrow 195. The wireless device 160a could therefore use wireless device 160b as Device-To-Network relay for receiving the group communication via the relay wireless device 160b (via connections 180 and 190). As will be described next, there is currently no service continuity procedure defined for this scenario.

In a public safety communication system one option to extend the

communication range is to use a Device-to-Network relay function. This allows a wireless device that is moving outside the radio coverage area to setup a communication path to another wireless device acting as a relay. The relay wireless device must be located in radio coverage of the network and will relay the traffic of the wireless device outside coverage to the network. One application of Device-to-Network relay is specified in 3GPP TS 23.303 V13.4.0 "Proximity-based services (ProSe); Stage 2". When MBMS is used in group communication it is possible for the wireless devices that listen to the group communication to stay in idle mode. This means that the wireless device only receives the group communication data and the transmitter of the wireless device could thus be turned off, which saves both battery resources in the wireless device and traffic resources in the communication system.

One possible scenario is that a wireless device that is out of coverage may also receive group communication over an MBMS bearer towards a relay wireless device, and the relay wireless device will forward the data on a device-to- device channel. This can be done in a one-to-one communication path or in a one-to-many communication path.

According to the existing Device-to-Network relay function the wireless device that is (potentially) leaving the coverage area could set up a relay connection too late. In more detail, the wireless device would typically try to establish a connection towards a relay wireless device when the radio signal is becoming weak or is lost, and via that relay connection inform the network about the newly established network connection. Packet loss probability is therefore comparatively high. Furthermore a wireless device that is at cell border is very costly from a network resources perspective; typically robust coding and intense retransmission is used, which results in high consumption of communication resources. That is, it could be challenging to handle group communication for wireless devices close to coverage area borders.

According to some aspects the client node 200a of wireless device 160a (hereinafter denoted host wireless device 160a) receiving broadcast group communication data (such as PTT over an MBMS bearer) triggers a transfer of the connection to another wireless device 160b (hereinafter denoted relay wireless device 160b) when the quality of the MBMS bearer is below a certain threshold. One benefit of this is that the client node 200a may switch to the relay wireless device 160b before the wireless device 160a loses the network connection completely, which might not be acceptable. Furthermore, as noted above, a switch to reception of the group communication using a unicast bearer at this stage may be costly from a resource efficiency

perspective since the wireless device 16 oa that is close to the cell border could be a heavy consumer of network resources.

The embodiments disclosed herein particularly relate to mechanisms for handling group communication. In order to obtain such mechanisms there is provided a client node 200a, a method performed by the client node 200a, a computer program product comprising code, for example in the form of a computer program, that when run on a client node 200a, causes the client node 200a to perform the method. Figs. 3 and 4 are flow charts illustrating embodiments of methods for handling group communication. The methods are performed by the client node 200a. The methods are advantageously provided as computer programs 820.

Reference is now made to Fig. 3 illustrating a method for handling group communication as performed by the client node 200a according to an embodiment. The client node 200a is hosted by the host wireless device 160a.

S102: The client node 200a determines that signal quality of broadcast group communication received from the radio access network node 110a is below a signal quality threshold for reliable broadcast communication. In this respect, one examples of a mechanism to measure the signal quality of broadcast group communication is measurements of Reference Signal Received Quality (RSRQ), for example MBSFN RSRQ as defined in 3GPP TS 36.214 V13.1.0. When data is broadcasted the reception quality can be evaluated by analyzing the Transport Block Error Rate (BLER) of the data. When the group communication is broadcasted using an MBMS bearer the signal quality could, for example, be determined with the Reference Signal Received Quality, RSRQ, or Signal to Interference and Noise Ratio, SINR, for the MBMS bearer. Reliable broadcast communication could be defined by the area 130, 130'. That the signal quality of the broadcast group communication received from the radio access network node 110a is below the signal quality threshold for reliable broadcast communication could thus indicate that the host wireless device 160a is outside the area 130, 130' but still inside the radio coverage area 120 (defining reliable unicast communication).

Upon having determined that the signal quality is below the signal quality threshold the client node 200a seeks to find a wireless device 160b to act as a group communication relay. Hence, the client node 200a is configured to perform step S104:

S104: The client node 200a attempts discovery of the relay wireless device 160b for acting as group communication relay between the radio access network node 110a and the host wireless device 160a.

According to an aspect, the client node 200a attempts discovery of the relay wireless device 160b for acting as group communication relay between the radio access network node 110a and the host wireless device 160a prior to the determining in step S102. For example, the client node 200a could be configured to continuously monitor its surroundings in search of a potential relay wireless device 160b for acting as group communication relay between the radio access network node 110a and the host wireless device 160a.

According to another aspect, the client node 200a is configured to maintain, and periodically update, a list of potential relay wireless devices 160b for acting as group communication relay between the radio access network node 110a and the host wireless device 160a. Due to the above described aspects of the attempting discovery, it is appreciated that steps S102 and S104 can be performed in any order, be performed in parallel, or be performed simultaneously or concurrently.

According to the present embodiment it is assumed that a relay wireless device 160b is discovered in step S104. The client node 200a therefore initiates establishment of a connection with the relay wireless device 160b. Hence, the client node 200a is configured to perform step S106:

S106: The client node 200a initiates, when the relay wireless device 160b is discovered, a connection between the host wireless device 160a and the relay wireless device 160b in order for the relay wireless device 160b to act as relay for the group communication from the radio access network node 110a to the client node 200a.

Examples of operations, or steps, the client node 200a could be configured to perform when a relay wireless device 160b is not discovered in step S104 will be disclosed below.

A client node 200a of a host wireless device 160a that is leaving the area of MBMS coverage may thus according to steps S102, S104, S106 trigger a discovery procedure to initiate the establishment of a relay communication path to the relay wireless device 160b. The signal quality threshold could be defined as being above a reference threshold given by outage of reception of the broadcast group communication from the radio access network node 110a. In some aspects the signal quality threshold represents a signal quality higher than the signal quality where a unicast connection to the radio access network node 110a is in jeopardy. Embodiments relating to further details of handling group communication as performed by the client node 200a will now be disclosed.

There could be different ways for the client node 200a to receive the group communication. According to an embodiment the group communication is received on an MBMS bearer from the radio access network node 110a, and the signal quality is then determined for the MBMS bearer. That is, according to some embodiments it is assumed that the host wireless device 160a is not using a unicast bearer for receiving the group communication when any of steps S102, S104, S106 are performed. According to an embodiment the host wireless device 160a is in idle mode during the determining step S102. There could be different ways for the host wireless device 160a to discover the relay wireless device 160b in step S104. According to an embodiment the relay wireless device 160b is discovered by the host wireless device 160a using a ProSe (where ProSe is short for Proximity Services) Direct Discovery procedure. One example of such a ProSe Direct Discovery procedure is defined in 3GPP TS 23.303 V13.4.0. That is, the relay wireless device 160b could be discovered during a ProSe Direct Discovery procedure over interface PC ₅ .

There could be different types of connections between the host wireless device 160a and the relay wireless device 160b.

According to an embodiment the connection between the host wireless device 160a and the relay wireless device 160b is a ProSe direct communication as defined in 3GPP TS 23.303 V13.4.0. According to an embodiment the connection between the host wireless device 160a and the relay wireless device 160b is a WiFi® connection as standardized in IEEE 802.11 (where IEEE is short for Institute of Electrical and Electronics Engineers). Further, according to an embodiment the connection between the host wireless device 160a and the relay wireless device 160b is a Land Mobile Radio (LMR) device to device connection or a Private Mobile Radio (PMR) device to device connection.

Reference is now made to Fig. 4 illustrating methods for handling group communication as performed by the client node 200a according to further embodiments. It is assumed that steps S102, S104, S106 are performed as described above with reference to Fig. 3 and a thus repeated description thereof is therefore omitted.

When the connection to the relay wireless device 160b has been established, the client node 200 could, by means of the host wireless device 160a, inform the relay wireless device 160b about the client node's 200 interested in data sent on a specific group over MBMS. Hence, according to an embodiment the client node 200a is configured to perform step S108: S108: The client node 200a notifies the relay wireless device 160b to act as relay for the group communication from the radio access network node 110a to the client node 200a.

The relay wireless device 160b could then inform the control node 300 of its ability to relay group communication data to the client node 200a.

When the connection to the relay wireless device 160b has been established the the client node 200 could continue to receive the group communication via the relay wireless device 160b. Hence, according to an embodiment the client node 200a is configured to perform step S110: S110: The client node 200a receives the group communication from the radio access network node 110a on the connection between the host wireless device 160a and the relay wireless device 160b.

The client node 200a may still be able to receive the group communication on the MBMS bearer. Hence, according to an embodiment the client node 200a is configured to perform step Sii2a after the initiating step S106:

Sii2a: The client node 200a maintains reception of the broadcast group communication from the radio access network node 110a.

Alternatively, the client node 200a determines to terminate reception of the group communication on the MBMS bearer. Hence, according to an embodiment the client node 200a is configured to perform step Sii2b after the initiating step S106:

Sii2b: The client node 200a terminates reception of the broadcast group communication from the radio access network node 110a.

This could prevent the broadcast group communication to be replaced by unicast group communication which may otherwise occur. It could be that the relay wireless device 160b is not discovered in step S104. According to an embodiment the client node 200a is configured to perform step S114 in case a relay wireless device 160b is not discovered in step S104:

S114: The client node 200a initiates a unicast bearer connection between the host wireless device 160a and the radio access network node 110a to provide group communication from the radio access network node 110a to the client node 200a.

In further aspects the relay wireless device 160b may have respective connections to more than one host wireless device. In this respect, a relay wireless device 160b acting as a ProSe Device-to-Network Relay may relay evolved MBMS (eMBMS) traffic using a one-to-many ProSe Direct

Communication link. That is, the relay wireless device 160b could act as relay for group communication from the radio access network node 110a to a plurality of client nodes. In this respect the relay wireless device 160b could have unicast bearer connection with the radio access network node 110a and have a broadcast bearer connection with the host wireless devices.

One particular embodiment for handling group communication as performed by the client node 200a, the relay wireless device 160b, and the control node 300 based on at least some of the above embodiments will now be disclosed with reference to the signalling diagram of Fig. 5.

Parallel references are made to Figs. 1 and 2. Assume for illustrative purposes that wireless device 160a listens to broadcast group communication (via connection 170) from radio access network node 110a and moves outside the area 130, 130', as illustrated by arrow 195. S201: The client node 200a estimates the MBMS bearer quality. The client node 200a also measures on reference signals transmitted from a radio access network node of another cell to estimate the possibilities to transfer to unicast and handover to another cell. One way to implement step S201 is to perform step S102. S202: If the MBMS bearer quality has reach a certain threshold (i.e., is below the signal quality threshold for reliable broadcast communication) the client node 200a performs a ProSe Device-To-Network relay discovery procedure over interface PC5 and establishes a secure point-to-point link with the relay wireless device 160b (denoted UE-R) over interface PC5. As part of the process to establish a ProSe Direct Communication the host wireless device 160a is mutually authenticated at PC5 layer with either the relay wireless device 160b or with the network as specified in 3GPP TS 23.303 V13.4.0 "Proximity-based services (ProSe); Stage 2". One way to implement step S202 is to perform any of steps S104, S106.

S203: Normal service continues for the Device-To-Network connection as disclosed in Annex A of 3GPP TS 23.179 V13.3.0. One way to implement step S203 is to perform step S110.

S204: The client node 200a informs the relay wireless device 160b about the service continuity needs for the media that it is receiving over the MBMS bearer by sending a request for reception of media over MBMS bearer. One way to implement step S204 is to perform step S108.

S205: The relay wireless device 160b will request the group communication service for the client node 200a to be transferred over an MBMS bearer to the relay wireless device 160b on behalf of the client node 200a by sending a message with request for MC service over the MBMS bearer on behalf of the MC service client (i.e., on behalf of client node 200a).

The wireless device 160a thereafter uses wireless device 160b as Device-To- Network relay for receiving the group communication via the relay wireless device 160b (via connections 180 and 190).

Fig. 6 schematically illustrates, in terms of a number of functional units, the components of a client node 200a according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 810 (as in Fig. 8), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). Particularly, the processing circuitry 210 is configured to cause the client node 200a to perform a set of operations, or steps, S102-S114, S201-S204, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the client node 200a to perform the set of operations. The set of operations may be provided as a set of executable instructions.

Thus the processing circuitry 210 is thereby arranged to execute methods as herein disclosed. The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The client node 200a may further comprise a

communications interface 220 at least configured for communications with the host wireless device 160a, the relay wireless device 16b (or its hosted client node 200b) and the control node 300. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components. The processing circuitry 210 controls the general operation of the client node 200a e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the client node 200a are omitted in order not to obscure the concepts presented herein.

Fig. 7 schematically illustrates, in terms of a number of functional modules, the components of a client node 200a according to an embodiment. The client node 200a of Fig. 7 comprises a number of functional modules; a l8 determine module 210a configured to perform step S102, a discover module 210b configured to perform step S104, and an initiate module 210c configured to perform step S106. The client node 200a of Fig. 7 may further comprises a number of optional functional modules, such as any of a notify module 2iod configured to perform step S108, a receive module 2ioe configured to perform step S110, a maintain module 2iof configured to perform step Sii2a, a terminate module 2iog configured to perform step Sii2b, and an initiate module 2ioh configured to perform step S114.

In general terms, each functional module 2ioa-2ioh may in one embodiment be implemented only in hardware or and in another embodiment with the help of software, i.e., the latter embodiment having computer program instructions stored on the storage medium 230 which when run on the processing circuitry makes the client node 200a perform the corresponding steps mentioned above in conjunction with Fig 7. It should also be mentioned that even though the modules correspond to parts of a computer program, they do not need to be separate modules therein, but the way in which they are implemented in software is dependent on the programming language used. Preferably, one or more or all functional modules 2ioa-2ioh may be implemented by the processing circuitry 210, possibly in cooperation with functional units 220 and/or 230. The processing circuitry 210 may thus be configured to from the storage medium 230 fetch instructions as provided by a functional module 2ioa-2ioh and to execute these instructions, thereby performing any steps as disclosed herein.

The client node 200a may be provided as a standalone device or as a part of at least one further device. For example, the client node 200a may be hosted by, provided in, or installed on a wireless device 160a

Fig. 8 shows one example of a computer program product 810 comprising computer readable storage medium 830. On this computer readable storage medium 830, a computer program 820 can be stored, which computer program 820 can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 820 and/or computer program product 810 may thus provide means for performing any steps as herein disclosed. In the example of Fig. 8, the computer program product 810 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 810 could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 820 is here schematically shown as a track on the depicted optical disk, the computer program 820 can be stored in any way which is suitable for the computer program product 810.

The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.