OA18163A - Methods and nodes for decoding of contention based uplink transmissions - Google Patents

Abstract

A network node (200), a wireless device (202) and methods therein, for decoding of contention based uplink transmissions of data in a cell served by the network node. The network node (200) registers the wireless device (202) for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data, e.g. when receiving a registration request sent from the wireless device, such that the wireless device (202) is included in a set (200a) of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell. The network node (200) then performs blind decoding of uplink signals transmitted on the radio resource by considering the wireless devices in the set. In this way, the decoding is made more efficient by disregarding any other wireless devices in the cell which are not registered for contention based uplink transmissions of data on the radio resource in the cell.

Description

METHODS AND NODES FOR DECODING OF CONTENTION BASED UPLINK TRANSMISSIONS

Technical field

The présent disclosure relates generally to a network node of a radio network, a wireless device and methods therein, for decoding of contention based uplink transmissions of data in a cell served by the network node.

Backqround

In the field of mobile or wireless communication, the term “wireless device” or just “device” for short, is often used and will be used in this disclosure to represent any wireless communication entity capable of radio communication with a radio network by sending and receiving radio signais, such as e.g. mobile téléphonés, tablets and laptop computers. Another common term in this field is “User Equipment, UE”. A wireless device in this context could also be a machine-tomachine type of device operating automatically such as a sensor, counter or measuring entity which is configured to send reports over the radio network e.g. at certain intervals or upon certain events.

Further, the term “network node”, sometimes also referred to as a base station, radio node, eNodeB, eNB, NB, base transceiver station, access point, etc., is used here to represent any node of a radio network that is arranged to communicate radio signais with wireless devices. The network node described here may, without limitation, be a so-called macro base station or a low power base station such as a micro, pico, femto, Wifi or relay node, to mention some customary examples. Throughoutthis disclosure, the terms “base station” and “UE” could alternatively be used instead of network node and wireless device, respectively.

In a typical radio network for wireless communication, a multitude of different wireless devices are frequently communicating by transmitting data over uplink data channels to network nodes serving different cells in the radio network. The normal procedure is that a wireless device intending to transmit data must first transmit a scheduling request to its serving network node and then await an uplink grantfrom the network node which spécifiés a radio resource, e.g. in terms of subframes on a certain frequency and/or channel, being reserved for the data transmission. This procedure is sometimes referred to as access réservation.

However, since it has become more and more common that many wireless devices frequently need to transmit only quite small amounts of data at irregular and unpredictable intervals, the above-described access réservation procedure with request and grant before each data transmission becomes a burden and créâtes a great “overhead” of signaling and delays for both the wireless device and the network node to handle. The access réservation procedure thus requires substantial amounts of control signaling and processing for communicating relatively small amounts of data, and also causes latency in the data communication. Another drawback is that power consumption is high in the wireless device. As a resuit, it has been suggested in the Third Génération Partnership project, 3GPP, that contention-based uplink transmission can be employed instead ofthe above-described access réservation for such data transmissions. Some examples of how contention-based uplink transmissions can be employed are described in WO 2010057540 A1.

Contention-based uplink transmission means that any wireless device can transmit data to a serving network node on a common radio resource at the risk of collision when two or more devices happen to transmit simultaneously. This works well as long as there are only a limited number of wireless devices in the cell and collisions occur rarely. Some network nodes are equipped with advanced receivers capable of so-called Multi-User Détection, MUD, so that transmissions received from more than one wireless device at the same time can be decoded. The network node receiving such a contention-based uplink transmission is able to détermine the transmitting device and décodé the transmitted data by performing so-called “blind decoding” based on some identifier of each potential transmitting device. This means that the network node must attempt to décodé the received transmission based on one identifier at the time, thus performing blind decoding across ail devices in the cell by going through the identifiers, one by one, of ail wireless devices that may potentially hâve transmitted the received data. Examples of how blind decoding of a received transmission can be performed are described in US 20090154607 A1.

It is however a problem that when a network node is serving a great number of wireless devices, itwill need to perform blind decoding across ail of these wireless devices in orderto décodé a received contention-based uplink transmission. Fig. 1 illustrâtes a communication scénario where the feature of contention-based uplink transmission is employed e.g. on a spécifie radio resource or channel reserved for such transmissions. This figure shows that multiple wireless devices D1-D6 are being served by a network node 100 in a cell 102. In reality, there may be a much larger number of devices being served by the same network node and this figure only illustrâtes this schematically. According to conventional procedures, the network node 100 performs blind decoding across ail of these wireless devices D1- D6 in order to identify and décodé a received contention-based uplink transmission, which is therefore a quite complex and processing-heavy operation when the number of devices is large. The risk for failed decoding also increases with the number of potential wireless devices présent in the cell such that the transmitting device hâve to try again by re-transmitting its data.

If the devices D1- D6 also can use different transmission formats, or Modulation and Coding Schemes, MCSs, each potential wireless device needs to be tested by the network node 100 for ail possible transmission formats or MCSs, thereby requiring the network node to perform the blind decoding not only across a large number of devices but also over ail possible transmission formats, resulting in a huge number of possible hypothèses for each received transmission.

Summary

It is an object of embodiments described herein to address at least some of the problems and issues outlined above. It is possible to achieve this object and others by using a method and a network node as defined in the attached independent claims.

According to one aspect, a method is performed by a network node of a radio network, for decoding of contention based uplink transmissions of data in a cell served by the network node. In this method, the network node registers a wireless device for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. The network node then performs blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

According to another aspect, a network node of a radio network is arranged for decoding of contention based uplink transmissions of data in a cell served by the network node. The network node comprises means configured to register a wireless device for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. The network node also comprises means configured to perform blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

According to another aspect, a method is performed by a wireless device for enabling a network node of a radio network to décodé contention based uplink transmissions of data in a cell served by the network node. In this method, the wireless device sends a registration request to the network node for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. The wireless device then receives an acknowledgement from the network node indicating that the wireless device is registered for contention based uplink transmissions of data in the cell. The wireless device further transmits data on the radio resource, thereby enabling the network node to perform blind decoding of the data by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

According to another aspect, a wireless device is arranged to enable a network node of a radio network to décodé contention based uplink transmissions of data in a cell served by the network node. The wireless device comprises means configured to send a registration request to the network node for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. The wireless device also comprises means configured to receive an acknowledgement from the network node indicating that the wireless device is registered for contention based uplink transmissions of data in the cell. The wireless device further comprises means configured to transmit data on the radio resource, thereby enabling the network node to perform blind decoding ofthe data by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

The above network node, wireless device and methods therein may be implemented and configured according to different optional embodiments to accomplish further features and benefits, to be described below.

A computer program is also provided comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out either of the above methods. A carrier is also provided which contains the above computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or a non-tangible computer readable storage medium.

Brief description of drawings

The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which:

Fig. 1 is a communication scénario illustrating a network node receiving contention based uplink transmissions in a cell, according to the prior art.

Fig. 2 is a block diagram illustrating a procedure for decoding of contention based uplink transmissions in a network node, according to some possible embodiments.

Fig. 3 is a flow chart illustrating a procedure in a network node, according to further possible embodiments.

Fig. 4 is a flow chart illustrating a procedure in a wireless device, according to further possible embodiments.

Fig. 5 is another flow chart illustrating a more detailed example of a procedure in a network node, according to further possible embodiments.

Fig. 6 is another flow chart illustrating a more detailed example of a procedure in a wireless device, according to further possible embodiments.

Fig. 7 is a block diagram illustrating a network node and a wireless device in more detail, according to further possible embodiments.

Detailed description

Briefly described, a solution is provided to facilitate the process in a network node of decoding contention based uplink transmissions of data in a cell served bythe network node. As explained above, in conventional procedures the network node needs to perform blind decoding across a great number of wireless devices, and perhaps also over different possible MCSs, when receiving such contention based uplink transmissions. In this solution however, the network node is able to perform blind decoding of uplink signais transmitted on the radio resource by considering only a reduced number of wireless devices that are registered for contention based uplink transmissions of data on the radio resource in the cell. This means that the network node can disregard any other wireless devices in the cell which are not registered in this way, when performing the blind decoding, and the number of devices to consider in this operation can thereby be substantially reduced.

Furthermore, the wireless devices may also hâve been registered with préférences regarding communication parameters, which may refer to, e.g., uplink and downlink channels, MCS, Hybrid automatic repeat request (HARQ), timing advance, power control, header compression, etc. In that case, the network node may be aware of which MCS will be used by the registered wireless devices when transmitting and can thus limit the blind decoding to the possible MCS(s) according to the préférences of the registered devices.

Some features of this procedure will now be outlined with reference to a communication scénario illustrated in Fig. 2, involving a network node 200 serving various wireless devices in a cell and a shown wireless device 202 being served by the network node 200. In this procedure, the wireless device 202 sends a registration request to the serving network node 200, for contention based uplink transmissions of data, as shown in an action 2:1.

For example, the wireless device 202 may hâve decided or detected that it will hâve data to transmit in quite small amounts but on several different occasions, and that this transmission pattern would benefit from contention based uplink transmissions of the data in order to avoid overhead signalling. An illustrative but non-limiting example of such a transmitting behaviour is when the wireless device is a sensor or the like configured to send measurement reports frequently, where each report contains a small amount of data but the reports are to be sent many times according to some scheme. In general, the wireless device 202 may hâve decided e

or detected, for whatever reason, that the overhead signalling associated with the conventional access réservation procedure requiring request and grant should be avoided.

When receiving the registration request, the network node 200 takes a decision whether to registerthe wireless device 202 or not, as shown in another action 2:2. This decision may be based on various factors which wili be described in more detail later below. In this example, the network node 200 registers the wireless device 202, in another action 2:3, for contention based uplink transmissions of data on a spécifie radio resource which is reserved for contention based uplink transmissions of data. As an alternative to requiring a registration request from the wireless device 202, it may be registered automatically on a “higher level” for contention based transmissions, e.g. based on preferences orsettings in a subscription or similar. In this case, the registration request of action 2:1 can be omitted thus further reducing the signalling overhead.

In either case, the network node 200 registers the device 202 by including it in a set of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, which is shown by another action 2:4. Action 2.4 can thus be regarded as being part of the registration action 2:3. This set of registered wireless devices 200a may be maintained as a list or the like in the network node 200. The list may contain at least a suitable identifier of each wireless device in the set 200 which may be used in the blind decoding operation, and optionally also preferences regarding communication parameters if any hâve been registered for the respective device.

In this example, the network node 200 further sends an acknowledgement to the wireless device 202, in an action 2:5, to indicate that it is registered and included in the set. Another action 2:6 illustrâtes that the wireless device 202 at some point transmits data on the radio resource reserved for contention based uplink transmissions of data, which the device is effectively allowed to do since it has been registered and added to the set of registered wireless devices in actions 2:3 and 2:4.

A final action 2:7 illustrâtes that the network node 200 performs blind decoding of uplink signais transmitted on the radio resource by considering the wireless devices in the set 200a, and thus disregarding any other wireless devices in the cell which are not in the set 200a. For exampie, the blind decoding may be performed by the network node in this action based on an identifier of each wireless device in the set. This identifier may further be a Cell Radio Network Temporary Identity, C-RNTI. The technique used for performing the actual operation of blind decoding may be conventional as such and is somewhat outside the scope of this solution. Anyway, since the wireless device 202 has been registered and included in the set, the network node is able to identify device 202 and décodé its transmission by considering only the set 200a.

Advantages of this solution include a simplified and more reliable operation of blind decoding by limiting the number of possible devices to the above-described set 200a and possibly also to a reduced number of potential MCSs according to their preferences, if any. Another advantage is that the network node 200 can estimate the current need for contention based uplink transmissions of data in the cell based on the number of registered devices in the set, so that the network node 200 can configure and tune the radio resource reserved therefor accordingly in a flexible manner and on a dynamic basis.

An example of a procedure, performed by a network node of a radio network when the solution is employed, will now be described with reference to the flow chart in Fig. 3. In this procedure, the network node is opérable for decoding of contention based uplink transmissions of data in a cell served by the network node, as follows. The procedure thus involves the network node and a wireless device which may be the above-described network node 200 and wireless device 202, respectively.

A first action 300 illustrâtes that the network node registers a wireless device for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. This action may be made so that the wireless device is included in a set of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, as shown by another action 302 which thus may be seen as part of action 300. An optional action 304 illustrâtes that the network node may, according to a possible embodiment, send an acknowledgement to the wireless device indicating that the wireless device is registered for contention based uplink transmissions of data on the radio resource, and is thereby included in the set.

A final action 306 illustrâtes that the network node performs blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource, i.e. the wireless devices in the set. This means that the network node can disregard any other non-registered wireless devices in the cell which are not in the set, when performing the blind decoding, which is an advantage as explained above. Thereby ,the same advantages may be achieved as those described above for Fig. 2.

Some optional but non-limiting embodiments will now be described which may be used for the network node. In some possible embodiments, the network node may détermine whether to registerthe wireless device or not based on at least one of:

- The current load on the radio resource, i.e. referring to the amount of data currently being transmitted by registered wireless devices on the radio resource reserved for contention based uplink transmissions of data. For example, if the current load on the radio resource is close to or above a maximum limit, the network node may décidé not to register the wireless device in order to avoid congestion on the radio resource that could resuit in collisions and failure ofthe blind decoding. It is also possible for the network node to remove one or more wireless devices from the set, e.g. if the blind decoding frequently faiJs due to many collisions or poor signal réception, to improve the blind decoding.

- The current traffic load in the cell. For example, if the current traffic load in the cell is high and exceeds a certain level, the network node may décidé not to register the wireless device.

- Measurements of signais received from the wireless device, e.g. related to signal strength, signal quality, bit error rate, block error rate, etc. For example, the network node may décidé to register the wireless device if the signal measurements indicate a sufficiently good réception ofthe signais while if the signal réception is poor, the network node may décidé not to register the wireless device since transmissions from the wireless device will be difficult to décodé.

- The current number of registered wireless devices, thus being included in the set. For example, the network node may décidé to register the wireless device only if the number of registered wireless devices remains below a maximum limit. The maximum number of registered devices in the set may be variable depending on, e.g., the current load on the radio resource and/or the current traffic load in the cell. For example, when the current load on the radio resource is relatively low, a larger number of registered devices in the set may be allowed than when the current load is relatively high.

- A subscription setting valid for the wireless device. For example, the wireless device may hâve a subscription that allows the wireless device to be registered for contention based uplink transmissions of data on the radio resource, e.g. at ail times or at certain times and/or under certain circumstances.

- Preferences ofthe wireless device regarding communication parameters, e.g. related to uplink and downlink channels, a spécifie MCS, a spécifie HARQ process, a certain timing advance, power control, header compression, to mention some illustrative but non-limiting examples.

in another possible embodiment, the wireless device may be registered for a predefined duration at predefined time intervals, such that the registration is effectively more or less “periodic”. Thereby, the network node may distribute or spread the transmission traffic by assigning different time intervals for different wireless devices, e.g. to reduce or avoid the risk of collisions. The predefined duration and predefined time intervals may in this embodiment further be selected and “tailored” depending on the device’s needs. It is also possible to group two or more wireless devices together on the same predefined time intervals so that the load on the radio resource is distributed in time. In this case, certain “matching” devices may further be grouped according to their capabilities and/or needs on the same predefined time intervals, so that utilization ofthe radio resource increase or maximize.

In further possible embodiments, the network node may de-register and remove the wireless device from the set based on at least one of:

- The radio resource is congested, e.g. meaning that the blind decoding of action 306 often fails due to many collisions as a resuit of too many transmissions on the radio resource.

- Poor réception of signais transmitted from the wireless device. As mentioned above, the network node may remove a wireless device from the set, if the blind decoding tends to fail due to poor signal réception from that device.

- A de-registration request has been received from the wireless device. For example, the wireless device may décidé not to transmit any further data, e.g. when there is no more data to send or when detecting that the contention based transmissions are not working such that re-transmissions are frequently necessary.

- A predefined inactivity duration when the wireless device has not transmitted any data has expired, which would indicate that the contention based transmissions are not needed anymore by the wireless device, at least not for some time. The wireless device is in that case free to send another registration request to the network node to become registered whenever the need for contention based transmissions of data arises again.

- A predefined registration duration when the wireless device has been registered has expired. This means that the wireless device is registered in action 300 for a limited period of time, i.e. until the predefined registration duration has expired.

As mentioned above, the wireless device may be registered when the network node receives a registration request from the wireless device, which is another possible embodiment. In further possible embodiments, the registration request may be received by the network node in a Radio Resource Control, RRC, connection request or an RRC connection re-establishment request, which are well-known messages as such.

In other possible embodiments, the above-mentioned registration request may comprise preferences regarding communication parameters that the device intends or prefers to use. Some non-limiting examples of such preferences may relate to preferred uplink and downlink channels, a preferred MCS, a preferred HARQ process, a preferred timing advance, a preferred power control mechanism, a preferred header compression, and so forth. Thereby, the wireless device may be registered with its preferences such that the network node will be aware of how the device will perform its contention based transmissions of data, which can further facilitate the blind decoding operation. In particular, the network node can limit the decoding attempts to the one MCS given in the device’s preferences.

In yet a possible embodiment, the network node may accept the preferences in the wireless device’s registration request and keep them in the registration, or the network node may modify the received preferences in the registration, e.g. if they are deemed unpractical or cannot be accepted for whatever reason. The network node may further modify the received preferences in the registration after some time if some circumstances such as traffic load hâve changed, i.e. at any time while the device remains registered and présent in the set of registered wireless devices.

In another possible embodiment, the network node may create different sets of registered wireless devices for contention based uplink transmissions of data on different radio resources, based on preferences of the wireless devices regarding communication parameters. Thereby, the network node is able to group different wireless devices together on different radio resources e.g. in order to optimize utilization of the radio resources. For example, a device that is likely to transmit according to a certain behavior may be assigned to use a radio resource together with another device that is likely to transmit according to a complementary or matching behavior. In another example, devices having the same or similar preferences regarding communication parameters may be assigned to use the same radio resource which would further facilitate the blind decoding operation in the network node.

In a further possible embodiment, the acknowledgement sent in action 304 may comprise a temporary identifier which is valid for contention based uplink transmissions of data at least in the cell served by the network, and the network node may thereby perform the blind decoding based on the temporary identifier.

In another possible embodiment, the network node may forward the wireless device’s registration to at least one other network node to make the registration valid across multiple cells of the radio network. Thereby, the wireless device will not need to send a new registration request each time it moves to another one of the multiple cells and is handed over to another network node that has received the device’s registration.

A further example of a procedure, performed by a wireless device when the solution is employed, will now be described with reference to the flow chart in Fig. 4. In this procedure, the wireless device is opérable to enable a network node of a radio network to décodé contention based uplink transmissions of data in a cell served by the network node, as follows. In this procedure the wireless device may be the wireless device 202 described above, and the network node may be the network node 200 described above.

A first action 400 illustrâtes that the wireless device sends a registration request to the network node for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. In another action 402, the wireless device receives an acknowledgement from the network node indicating that the wireless device is registered for contention based uplink transmissions of data on the radio resource in the cell. The wireless device may thus hâve been included in a set of wireless devices being registered for contention based uplink transmissions of data in the cell. Action 402 thus corresponds to action 304 in the previous example of Fig. 3 and it is assumed that the network node has performed the above-described actions 300 and 302 in response to receiving the registration request.

In a final shown action 404, the wireless device transmits data on the radio resource, thereby enabling the network node to perform blind decoding of the data by considering the wireless devices in the set in the manner described for action 306. Also in this procedure, the same advantages may be achieved as those described above for Fig. 2 and the network node may employ any of the embodiments described for Fig. 3.

Some optional but non-limiting embodiments may also be used for the wireless device which will now be described. In some possible embodiments, the wireless device may send the registration request in a Radio Resource Control, RRC, connection request or an RRC connection re-establishment request. In another possible embodiment, the wireless device may refrain from transmitting data on the radio resource in case a de-registration message is received from the network node indicating that the wireless device is removed from the set. Such a de-registration message has been described above for Fig. 3. In another possible embodiment, the wireless device may send a de-registration request to the network node when deciding not to transmit any further data, e.g. if there is no more data to transmit or if the contention based transmissions do not work properly which may force the device frequently to perform re-transmissions of the same data.

A more detailed example of how a network node may act when performing the procedure of Fig. 3, will now be described with reference to the flow chart in Fig. 5. A first action 500 illustrâtes that the network node receives a registration request from the wireless device, for contention based uplink transmissions on a radio resource. Such a registration request has been described above. In a following action 502, the network node décidés whether to admit the request and register the wireless device by including it in a set of registered devices, or not. Several examples of how such a decision can be made by the network node hâve been described above for Fig. 3 which is therefore not repeated here.

The network node may thus décidé to refuse the device’s request, as of action 504, e.g. because the radio resource is currently congested, the number of already registered wireless devices has reached a maximum limit, the signal réception is too poor, and so forth. At some point, the wireless device may send another registration request to the network node and the process may then retum to action 500, as indicated by a dashed arrow.

If however the network node décidés in action 502 to admit the device’s request, the wireless device is included in a set of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, in another action 506. The network node also sends an acknowledgement to the wireless device, in an action 508, to indicate that that the wireless device is now registered for contention based uplink transmissions of data on the radio resource in the cell and is thus included in the set. Thereby, the wireless device is allowed to transmit data on the radio resource, e.g. according to certain restrictions in the registration such as during a predefined duration at predefined time intervals.

A next action 510 in this procedure indicates schematically that the network node may consider whether to de-register the wireless device or keep the registration. If the wireless device is not de-registered, the network node performs blind decoding of uplink signais transmitted on the radio resource, in an action 512, by considering the wireless devices in the set, which in this case includes the above-mentioned wireless device. Actions 510 and 512 may be repeated as indicated by another dashed arrow.

At some point, the network node may décidé in action 510 to de-register the wireless device, e.g. because the radio resource has become congested, poor signal réception, the wireless device has sent a de-registration request, the wireless device has been inactive more than a certain maximum inactivity duration, or the wireless device has remained registered more than a certain maximum registration duration. If any of this occurs, the network node de-registers and removes the wireless device from the set, in an action 514. The network node also sends a deregistration message to the wireless device in action 516, to indicate that that the wireless device is no longer registered and has been removed from the set. A final action 518 illustrâtes that the network node performs blind decoding of contention based uplink transmissions on the radio resource, based on the updated set which now excludes the above-mentioned wireless device. The process may then return to action 500, as indicated by another dashed arrow, in case the wireless device sends another registration request to the network node.

A more detailed example of how a wireless device may act when performing the procedure of Fig. 4, will now be described with reference to the flow chart in Fig. 6. A first action 600 illustrâtes that the wireless device sends a registration request to the network node. The wireless device then détermines or detects in an action 602 whether the registration request has been admitted or not by the network node. If admitted, e.g. as indicated by an acknowledgementfrom the network node, the wireless device has been included in a set of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, and the wireless device at some point transmits data on the radio resource, as shown by an action 604. Thereby, the network node is able to perform blind decoding of the data by considering the wireless devices in the set which thus includes the above wireless device.

Another action 606 illustrâtes that the wireless device détermines or detects whether a deregistration message has been received from the network node or not. If not, the wireless device may return to action 604 of transmitting data on the radio resource. If however a deregistration message has been received from the network node in action 606, this message indicates that the wireless device has been removed from the set and the wireless device accordingly refrains from transmitting data on the radio resource, as shown by an action 608. The process may then return to action 600, as indicated by a dashed arrow, in case the wireless device sends another registration request to the network node.

The block diagram in Fig. 7 illustrâtes a detailed but non-limiting example of how a network node 700 and a wireless device 702, respectively, may be structured to bring about the abovedescribed solution and embodiments thereof. In this figure, the network node 700 and the wireless device 702may be configured to operate according to any of the examples and embodiments of employing the solution as described above, where appropriate, and as follows. Each of the first network node 700 and the wireless device 702 is shown to comprise a processor “P”, a memory “M” and a communication circuit “C” with suitable equipment for transmitting and receiving signais with information in the manner described herein.

The communication circuit C in each of the network node 700 and the wireless device 702 thus comprises equipment configured for communication with each other over a radio interface using a suitable protocol for radio communication depending on the implémentation.

The network node 700 comprises means configured or arranged to perform at least some of the actions 300-306 and 500-518 of the flow charts in Figs 3 and 5, respectively, in the manner described above. Further, the wireless device 702 comprises means configured or arranged to perform at least some of the actions 400-404 and 600-608 of the flow charts in Figs 4 and 6, respectively, in the manner described above. These actions may be performed by means of functional modules in the respective processor P in the network node 700 and the wireless device 702 as follows.

The network node 700 is arranged for decoding of contention based uplink transmissions of data in a cell served by the network node. The network node 700 comprises means configured to register a wireless device 702 for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. This may be done so that the wireless device 702 is included in a set 700b of wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell. This registering activity may be performed by an registering module 700a in the network node 700, e.g. in the manner described for actions 300 and 302 above.

The network node 700 also comprises means configured to perform blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, i.e. the wireless devices in the set 700b. This decoding activity may be performed by a decoding module 700c in the network node 700, e.g. in the manner described for action 306 above.

The wireless device 702 is arranged to enable a network node 700 of a radio network to décodé contention based uplink transmissions of data in a cell served by the network node 700. The wireless device 702 comprises means configured to send a registration request to the network node 700 for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data. This activity may be performed by a requesting module 702a in the wireless device 702, e.g. in the manner described for action 400 above.

The wireless device 702 also comprises means configured to receive an acknowledgement from the network node 700 indicating that the wireless device 702 is registered. This may be done so that the wireless device 702 is included in a set of wireless devices being registered for contention based uplink transmissions of data in the cell. This receiving activity may be performed by a receiving module 702b in the wireless device 702, e.g. in the manner described for action 402 above. The wireless device 702 further comprises means configured to transmit data on the radio resource, thereby enabling the network node 700 to perform blind decoding ofthe data by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell, i.e. the wireless devices in the set.

This transmitting activity may be performed by a transmission module 702c in the wireless device 702, e.g. in the manner described for action 404 above.

It should be noted that Fig. 7 illustrâtes various functional modules in the network node 700 and the wireless device 702, respectively, and the skilled person is able to implement these functional modules in practice using suitable software and hardware. Thus, the solution is generally not limited to the shown structures of the network node 700 and the wireless device 702, and the functional modules 700a,c and 702a-c therein may be configured to operate according to any of the features and embodiments described in this disclosure, where appropriate.

The functional modules 700a,c and 702a-c described above can be implemented in the network node 700 and in the wireless device 702, respectively, by means of program modules of a respective computer program comprising code means which, when run by the processor P causes the respective network node 700 and wireless device 702 to perform the abovedescribed actions and procedures. Each processor P may comprise a single Central Processing Unit (CPU), or could comprise two or more processing units. For example, each processor P may include a general purpose microprocessor, an instruction set processor and/or related chips sets and/or a spécial purpose microprocessor such as an Application Spécifie Integrated Circuit (ASIC). Each processor P may also comprise a storage for caching purposes.

Each computer program may be carried by a computer program product in each of the network node 700 and the wireless device 702 in the form of a memory having a computer readable medium and being connected to the processor P. The computer program product or memory M in each of the network node 700 and the wireless device 702 thus comprises a computer readable medium on which the computer program is stored e.g. in the form of computer program modules or the like. For example, the memory M in each node may be a flash memory, a Random-Access Memory (RAM), a Read-Only Memory (ROM) or an Electrically Erasable Programmable ROM (EEPROM), and the program modules could in alternative embodiments be distributed on different computer program products in the form of memories within the respective network node 700 and wireless device 702.

The solution described herein may be implemented in each of the network node 700 and the wireless device 702 by a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions according to any of the above embodiments, where appropriate. The solution may also be implemented at each of the network node 700 and the wireless device 702 in a carrier containing the above computer program, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

It was mentioned above that blind decoding may be performed by the network node based on an identifier of each wireless device in the set, such as a C-RNTI or some temporarily identifier assigned specifically for contention-based uplink transmissions of data on the radio resource reserved therefor. Further details of the embodiments will be described below.

The network node may maintain the set in a list of ail wireless devices being registered for contention-based access. The solution considers a contention-based access scheme where wireless devices are in RRC Connected Mode and therefore each wireless device will correspond to a spécifie C-RNTI. In legacy uplink data transmissions on PUSCH, the receiver détermines if it has correctly decoded the data by checking the CRC scrambled by the C-RNTI ofthe respective wireless devices. In that case the network node will only consider one C-RNTI, namely that of the wireless device that was scheduled on that resource.

In the case of contention-based/instant access for wireless devices in RRC Connected Mode, the network node would hâve no knowledge of what wireless device is sending and would hâve to consider ail wireless devices in the cell, that is, the full C-RNTI space. With this solution, the network node would only need to consider the wireless devices being registered for contentionbased data transmissions on the radio resource. These wireless devices, or rather their CRNTIs, will be kept in a list atthe network node and only this subset ofthe full C-RNTI space will be considered for decoding ofthe transmissions received on the radio resource. It should be noted that the above-described registration is not limited to the use of C-RNTI for connecting decoding success to the device identity, which is only an example relating to the decoding operation.

In a possible implémentation, the network node is able to hâve full control of this list of registered devices by being able both to deny contention-based registration requests from UEs as well as removing wireless devices from the list by sending de-registration messages. Approving/denying a registration request or adding/removing a wireless device from the list may dépend on signal réception, e.g. in terms of signal strength/quality measurements in uplink, block/bit error rate, cell congestion/load status, and so forth. A registration request can be included in an RRC connection request, could be carried out on RRC level, e.g. as a new RRC connection setup cause, negotiated over NAS signalling, etc. As mentioned above, the response to the request may be given by the network node in an RRC connection setup message. Similarly, an RRC connection re-establishment request may include the registration request and the response to the request may be included in an RRC connection reconfiguration message.

The network node may choose to de-register one or more wireless devices and send a deregistration message to these wireless devices which will then be removed from the set. The updated registered set will then détermine which wireless devices are allowed for contentionbased access and these devices will be considered as hypothèses in the operation of decoding contention-based transmissions on the radio resource.

In some possible embodiments, the registration information may comprise various preferences, e.g. relating to MCS, traffic patterns, coverage enhancement level, protocol preferences, etc. Some possible preferences are mentioned below.

Protocol preferences for contention-based access:

• HARQ • RLC AM/UM • Header compression • Timing Advance preference • Power control parameters preference

Preferences for uplink channels for contention-based access:

• PUCCH, e.g. related to SR, CQI, or ACK/NACK • PUSCH

Preferences for downlink channels for contention-based access:

• PDCCH, e.g. related to Pw Contrl Cmd, Harq info • PHICH, e.g. related to ACK/NACK procedures • PCFICH, e.g. related to PDCCH info in yet another embodiment, there could be different groups of radio resources reserved for contention-based transmissions of data, e.g. for different coverage enhancement levels or any other différences in settings. In that case, the wireless devices may perform registration for any these groups individually.

While the solution has been described with reference to spécifie exemplifying embodiments, the description is generally only intended to illustrate the inventive concept and should not be taken as limiting the scope ofthe solution. For example, the terms “network node”, “wireless device”, “contention based uplink transmissions”, “radio resource”, and “blind decoding” hâve been used throughout this disclosure, although any other corresponding entities, functions, and/or parameters could also be used having the features and characteristics described here. The solution is defined by the appended claims.

Claims (14)

1. A method, performed by a network node of a radio network, for decoding of contention based uplink transmissions of data in a cell served by the network node, the method comprising:

- registering a wireless device for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data, and

- performing blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

2. A method according to claim 1, wherein the network node détermines whether to register the wireless device or not based on at least one of:

a current load on the radio resource, a current traffic load in the cell, measurements of signais received from the wireless device, the current number of registered wireless devices, a subscription setting valid for the wireless device, and preferences ofthe wireless device regarding communication parameters.

3. A method according to any of claims 1-3, wherein the network node deregisters the wireless device based on at least one of:

the radio resource is congested, poor réception of signais transmitted from the wireless device, a de-registration request has been received from the wireless device, a predefined inactivity duration when the wireless device has not transmitted any data has expired, and a predefined registration duration when the wireless device has been registered has expired.

4. A method according to any of claims 1-4, wherein the wireless device is registered when receiving a registration request from the wireless device.

5. A method according to any of claims 1-5, wherein the network node sends an acknowledgement to the wireless device indicating that the wireless device is registered for contention based uplink transmissions of data on the radio resource in the cell.

6. A network node of a radio network, the network node being arranged for decoding of contention based uplink transmissions of data in a cell served by the network node, the network node comprising means configured to:

- register a wireless device for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data, and

- perform blind decoding of contention based uplink transmissions on the radio resource by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

7. A network node according to claim 6, wherein the network node is configured to détermine whether to register the wireless device or not based on at least one of:

a current load on the radio resource, a current traffic load in the cell, measurements of signais received from the wireless device, the current number of registered wireless devices, a subscription setting valid for the wireless device, and preferences of the wireless device regarding communication parameters.

8. A network node according to any of claims 6-7, wherein the network node is configured to de-register the wireless device based on at least one of:

the radio resource is congested, poor réception of signais transmitted from the wireless device, a de-registration request has been received from the wireless device, a predefined inactivity duration when the wireless device has not transmitted any data has expired, and a predefined registration duration when the wireless device has been registered has expired.

9. A network node according to any of claims 6-8, wherein the network node is configured to forward the wireless device’s registration to at least one other network node to make the registration valid across multiple cells of the radio network.

10. A method performed by a wireless device for enabling a network node of a radio network to décodé contention based uplink transmissions of data in a cell served by the network node, the method comprising:

- sending a registration request to the network node for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data,

- receiving an acknowledgement from the network node indicating that the wireless device is registered for contention based uplink transmissions of data in the cell, and

- transmitting data on the radio resource, thereby enabling the network node to perform blind decoding of the data by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource in the cell.

11. A method according to claim 10, wherein the wireless device refrains from transmitting data on the radio resource in case a de-registration message is received from the network node indicating that the wireless device is deregistered.

5

12. A method according to any of claims 10-11, wherein the wireless device sends a de-registration request to the network node when deciding not to transmit any further data.

13. A wireless device arranged to enable a network node of a radio network to décodé contention based uplink transmissions of data in a cell served by the

10 network node, the wireless device comprising means configured to:

- send a registration request to the network node for contention based uplink transmissions of data on a radio resource reserved for contention based uplink transmissions of data,

- receive an acknowledgement from the network node indicating that the wireless 15 device is registered for contention based uplink transmissions of data in the cell, and

- transmit data on the radio resource, thereby enabling the network node to perform blind decoding of the data by considering wireless devices being registered for contention based uplink transmissions of data on the radio resource

20 in the cell.

14. A wireless device according to claim 13, wherein the wireless device is configured to refrain from transmitting data on the radio resource in case a deregistration message is received from the network node indicating that the wireless device is de-registered.

25 15. A wireless device according to any of claims 12-14, wherein the wireless device is configured to send a de-registration request to the network node when deciding not to transmit any further data.