WO2017146619A1

WO2017146619A1 - Enabling uplink transmissions in a wireless communications network

Info

Publication number: WO2017146619A1
Application number: PCT/SE2016/050140
Authority: WO
Inventors: Damanjit Singh; Tomas Sundin
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-02-25
Filing date: 2016-02-25
Publication date: 2017-08-31

Abstract

A method performed by a network node (110) for enabling uplink transmissions in a wireless communications network (100) is provided. The network node (110) transmits a grant message granting a group of wireless devices (121-125) to perform uplink transmissions on a set of transmission resources in the wireless communications network (100) for a time period (T_grant,1). The grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices (121-125) for the set of transmission resources within the time period (T_grant,1). A network node (110) for enabling uplink transmissions in a wireless communications network (100) is also provided.10 Furthermore, a wireless device and a method therein for transmitting uplink transmissions in a wireless communications network (100) are also provided.

Description

ENABLING UPLINK TRANSMISSIONS IN A WIRELESS COMMUNICATIONS NETWORK

5 TECHNICAL FIELD

Embodiments herein relate to uplink transmissions in a wireless communications network. In particular, embodiments herein relate to a network node and method therein for enabling uplink transmissions in a wireless communications network, as well as, a wireless device and method therein for enabling uplink transmissions in a wireless 10 communications network.

BACKGROUND

In today's wireless communications networks a number of different technologies are used, such as Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division

15 Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible technologies for wireless communication.

These types of wireless communications networks typically comprises radio base

20 stations providing radio coverage over at least one respective geographical area forming a cell. The cell definition may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. Wireless devices, which also may be referred to herein as User Equipments, UEs, mobile stations, and/or wireless terminals, are served in the cells by

25 respective radio base stations and are communicating with and via respective radio base station. The wireless devices transmit data over an air or radio interface to the radio base stations in uplink, UL, transmissions and the radio base stations transmit data over an air or radio interface to the wireless devices in downlink, DL, transmissions.

Furthermore, these types of wireless communications networks usually operate in

30 the so-called licensed spectrum.

License Assisted Access, LAA, is a technology currently being developed within 3GPP which intends to allow wireless devices to also operate in the unlicensed radio spectrum. The unlicensed spectrum may here be used as a complement to the licensed 35 spectrum. Accordingly, wireless devices may connect in the licensed spectrum, e.g. in a primary cell or PCell, and use carrier aggregation to benefit from additional transmission capacity in the unlicensed spectrum, e.g. a secondary cell or SCell. This is commonly also be referred to as LTE-LAA.

It should also be noted that, as an alternative, it is possible to use licensed spectrum technology, such as, e.g. LTE, in a stand-alone fashion in an unlicensed band. This is commonly be referred to as LTE Unlicensed, LTE-U, and may require some modifications to the current LTE specification since the primary cell or P-cell in the licensed spectrum is no longer available. Regulatory requirements, however, may not permit transmissions in the unlicensed spectrum without prior channel sensing. This is because the unlicensed spectrum must be shared with other radios of similar or dissimilar wireless technologies. Today, the unlicensed spectrum is mainly used by equipment implementing the IEEE 802.1 1 Wireless Local Area Network, WLAN, standard. This standard is also known as WiFi. One example of how to perform the channel sensing before a transmission is to apply a so called Listen-Before-Talk, LBT, protocol, such as, e.g. defined in ETSI EN 301 893. The LBT protocol specifies that a transmitter must sense the received energy, e.g. received signal power, for a certain time period and determine if the received energy level exceeds certain detection thresholds. If the received energy level is below a threshold, the channel may be declared as IDLE and a transmission may be initiated. Otherwise, if the received energy level is above a threshold, the channel may declared as BUSY and the transmission may essentially be deferred until the channel is deemed to be IDLE. For example, if the received energy level is below -82 dBm over a 20 MHz channel, then the channel is assumed to be IDLE. If the received energy level is greater than -82 dBm, but lower than -62 dBm, an attempt may be made to detect a Wi-Fi preamble. If a WiFi preamble is successfully detected, the channel may be assumed to be BUSY. If no WiFi preambles are detected, the channel may be assumed to be IDLE. If the received energy level is greater than -62 dBm, then the channel is assumed to be BUSY. Hence, together with a back-off mechanism, the LBT-protocol potentially avoids collisions of transmissions in the unlicensed spectrum of the wireless communications network.

The scarcest resource in a wireless communications network is the available spectrum, licensed or unlicensed. Hence, it is important to make efficient use of this limited resource and thus improve the performance in the wireless communications network. SUMMARY

It is an object of embodiments herein to improve the performance of uplink transmissions in a wireless communications network. According to a first aspect of embodiments herein, the object is achieved by a method performed by a network node for enabling uplink transmissions in a wireless communications network. The network node transmits a grant message granting a group of wireless devices to perform uplink transmissions on a set of transmission resources in the wireless communications network for a time period, wherein the grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices for the set of transmission resources within the time period.

According to a second aspect of embodiments herein, the object is achieved by a network node for enabling uplink transmissions in a wireless communications network. The network node is configured to transmit a grant message granting a group of wireless devices to perform uplink transmissions on a set of transmission resources in the wireless communications network for a time period, wherein the grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices for the set of transmission resources within the time period.

According to a third aspect of embodiments herein, the object is achieved by a method performed by a wireless device for enabling uplink transmissions in a wireless communications network. The wireless device receives a grant message granting a group of wireless devices to perform uplink transmissions on a set of transmission resources in the wireless communications network for a time period, wherein the wireless device is comprised in the group of wireless devices and the grant message indicates at least one allocated listening period to the wireless device for the set of transmission resources within the time period. According to a fourth aspect of embodiments herein, the object is achieved by a wireless device for enabling uplink transmissions in a wireless communications network. The wireless device is configured to receive a grant message granting a group of wireless devices to perform uplink transmissions on a set of transmission resources in the wireless communications network for a time period, wherein the wireless device is comprised in the group of wireless devices and the grant message indicates at least one allocated listening period to the wireless device for the set of transmission resources within the time period.

By issuing a time-limited uplink transmission grant for a group of wireless devices as described above, which also may be seen as aggregated concurrent grants for uplink transmission to each of the wireless devices in the group of wireless devices, downlink scheduling overhead in the wireless communications network may be reduced while at the same time, to a large extent, avoiding uplink transmission collisions in the wireless communications network during loaded scenarios. Hence, the performance of uplink transmissions in a wireless communications network is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the embodiments will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the accompanying drawings, wherein:

Fig 1 is a schematic block diagram illustrating embodiments of network nodes and wireless devices in a wireless communications network,

Fig 2 is a flowchart depicting embodiments of a method in a network node, Fig 3 is a flowchart depicting embodiments of a method in a wireless device,

Fig 4 is an illustration of an example of an uplink transmission according to embodiments of network nodes and wireless devices,

Fig 5 is a block diagram depicting embodiments of a network node,

Fig 6 is a block diagram depicting embodiments of a wireless device.

DETAILED DESCRIPTION

The figures are schematic and simplified for clarity, and they merely show details which are essential to the understanding of the embodiments presented herein, while other details have been left out. Throughout, the same reference numerals are used for identical or corresponding parts or steps.

Fig. 8 depicts a wireless communications network 100 in which embodiments herein may operate. In some embodiments, the wireless communications network 100 may be a radio communications network such as a Long Term Evolution, LTE, network. Although, the wireless communications network 100 is exemplified herein as an LTE network, the wireless communications network 100 may also employ technology of any one of LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) or GSM, or any other similar network or system. The wireless communications network 100 may also be an Ultra Dense Network, UDN, which e.g. may transmit on millimetre- waves (mmW).

In some embodiments, the wireless communications network 100 may be a cellular or radio communication systems capable of operating in parts of the so-called unlicensed spectrum, i.e. utilizing transmission resources, e.g. frequency bands, carriers, or channels, which are shared and decentralized and not licensed to a particular type of scheduled wireless or radio communication. In other words, when a network operator owns the communication network and offers the implemented services to its subscribers over a set of carriers, the carriers are referred to as licensed carriers. A licensed carrier refers to a carrier that is licensed to a licensee that has an exclusive right to the spectrum in a defined area. The licensed carrier is e.g. licensed to the owner of a wireless communication network, i.e., the network operator. One advantage associated with a licensed spectrum and a licensed carrier is that the license enables the licensee to control the transmission resources. In the case of an unlicensed spectrum, any communication node, e.g. network node or wireless device, regardless of its subscription or affiliation to any operator is allowed to access transmission resources of the unlicensed spectrum. No operator is assigned or owns a license for operating the transmission resources of the unlicensed spectrum.

Furthermore, it should also be noted that the access of transmission resources on a licensed frequency spectrum may be contention-free, which means that the

transmission resources may only be used by those wireless devices which subscribe to a designated operator and by those network nodes that belongs to the network owned by the operator. Only the designated operator is assigned the license to operate such licensed frequency spectrum. On the contrary, the access of transmission resources on an unlicensed frequency spectrum may be referred to as contention-based.

Hence, in some embodiments, the wireless communications network 100 may be configured to provide License Assisted Access, LAA, for wireless devices to the unlicensed spectrum. In case of using LTE, this may be denoted as LTE-LAA. In some embodiments, the wireless communications network 100 may also be configured to provide stand-alone access to the unlicensed spectrum. In case of using LTE, this may be denoted as LTE Unlicensed, LTE-U.

The wireless communications network 100 comprises a network node 110. The network node 1 10 serves at least one coverage area 115. The coverage area 1 15 may in some cases also be referred to as a cell. In some embodiments, the network node 1 10 may be configured to provide stand-alone access or Licensed Assisted Access, LAA, in the unlicensed spectrum to wireless devices in the wireless communications network 100. In this case, communicating in the licensed spectrum may be referred to as

communicating on a primary carrier, i.e. a primary cell, PCell, for the LAA, while communicating in the unlicensed spectrum may be referred to as communicating on a secondary carrier, i.e. a secondary cell, SCell, for the LAA. The secondary carrier or SCell may operate with both uplink, UL, and downlink, DL, traffic.

The network node 1 10 may correspond to any type of network node or radio network node capable of communicating with a wireless device and/or with another network node, such as, e.g. be a base station, a radio base station, eNB, eNodeB, a Home Node B, a Home eNode B, femto Base Station (BS), pico BS, etc., in the wireless communications network 100. Further examples of the network node 1 10 may also be e.g. repeater, base station (BS), multi-standard radio (MSR) radio node such as MSR BS, eNodeB, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), access point (AP), transmission points, transmission nodes, a Remote Radio Unit (RRU), a Remote Radio Head (RRH), nodes in distributed antenna system (DAS), core network node (e.g. MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g. E-SMLC), MDT, etc. In the unlicensed spectrum, the network node 1 10 may also be referred to as an access point, AP.

In Fig. 8, a number of wireless devices 121-129 are located within the coverage area 1 15. The wireless devices 121 -129 are configured to communicate within the wireless communications network 100 via the network node 1 10 over a radio link served by the network node 1 10. The wireless devices 121 -129 may refer to any type of wireless device or user equipment (UE) communicating with a network node and/or with another wireless device in a cellular, mobile or radio communication network or system. Examples of such a wireless devices are mobile phones, cellular phones, Personal Digital

Assistants (PDAs), smart phones, tablets, sensors equipped with a UE, Laptop Mounted Equipment (LME) (e.g. USB), Laptop Embedded Equipments (LEEs), Machine Type Communication (MTC) devices, or Machine to Machine (M2M) device, Customer Premises Equipment (CPE) , target device, device-to-device (D2D) wireless device, wireless device capable of machine to machine (M2M) communication, etc. In the unlicensed spectrum, the wireless devices 121 -129 may also be referred to as stations, ST As.

It should be noted that within the context of the present application, the term "wireless communications network", or short "network", may particularly denote a collection of nodes or entities, related transport links, and associated management needed for running a service. The service may, for example, be a wireless telephony service or packet transport service. Depending on the service, different node types or entities may be utilized to realize the service.

As part of developing the embodiments herein, it was realized that the available frequency spectrum, licensed or unlicensed , is the scarcest resource in a wireless communications network. Hence, it is important to make efficient use of this limited resource and thus improve the performance in the wireless communications network.

However, in the unlicensed spectrum, the network nodes and wireless devices are only allowed to transmit when the channel is not occupied by any other network node or wireless device sharing the same unlicensed spectrum. This will lead to some complications when, for example, attempting to perform uplink LTE-LAA or LTE-U transmissions on the channel in the unlicensed spectrum in an efficient way.

For example, a wireless device may only transmit in the LTE-LAA or LTE-U uplink if it has received a grant message from network transmitted in the downlink. If the wireless device then finds the channel in the unlicensed frequency band busy during the validity of the received grant message, then the downlink transmission resource used for sending the grant message was wasted. Other technologies in the unlicensed spectrum, such as, e.g . WiFi, does not require any uplink grant message and therefore no downlink transmission resource is needed for any grant message; while this does not lead to any efficiency loss due to wasted downlink transmission resources, one problem is that the use of the channel is completely asynchronous. This will lead to inefficiencies in loaded scenarios due to many uplink transmissions colliding and disturbing each other. Hence, it is noted that both the scheduled uplink solution of LTE-LAA or LTE-U and the contention-based solution according to the WiFi standard suffer from

inefficiency.

These issues are addressed by the embodiments described herein. Example of embodiments of a method performed by a network node 1 10 for enabling uplink transmissions in a wireless communications network 100 will now be described with reference to the flowchart depicted in Fig. 2. Fig. 2 is an illustrated example of actions or operations which may be taken by a network node 1 10 in the 5 wireless communication network 100. The method may comprise the following actions.

Action 201

According to some embodiments, the network node 1 10 may initially determine a group of wireless devices 121-125 based on a selection criteria. The selection criteria may

10 be based on the service requirements of the wireless devices in the group of wireless devices 121 -125, wherein the service requirements may comprise, for example, Voice over IP, VoIP, best effort data, etc. Also, the selection criteria may be based on the capabilities of the wireless devices in the group of wireless devices 121 -125, wherein the capability may comprise, for example, whether or not a wireless device supports MIMO.

15 Furthermore, the selection criteria may also be based on measurement reports from the wireless devices in the group of wireless devices 121-125, wherein the measurement reports may comprise reports indicating when a wireless device is close to or far away from the edge of a cell, reports indicating that a wireless device supports high rank transmissions, etc. Another selection criteria may be based on the positions or locations

20 of the wireless devices 121-125 in the wireless communications network 100, for

example, by selecting wireless devices 121 -125 that are well separated in space from each other. It is in this case a high likelihood that at least one of the wireless devices 121- 125 does not have another network node transmitting in its vicinity, thus leading to a high probability that at least one of the wireless devices 121 -125 may utilize use the grant

25 message transmitted in Action 202 as described below. Further selection criteria are also envisioned, such as, for example, according to a network operator's own selection or requirements, or according to a random selection. In other words, the network node 1 10 may group a number of wireless devices 121 -125 for uplink scheduling in a set of wireless devices.

30 In some embodiments, the network node 1 10 may determine at least a second group of wireless devices 126-130 based on at least a second selection criteria. The at least second selection criteria may be based on one or more of: the service requirements of the wireless devices in the at least second group of wireless devices 126-130; the capabilities of the wireless devices in the at least second group of wireless devices 126-

35 130; and measurement reports from the wireless devices in the at least second group of wireless devices 126-130. This advantageously enables the network node 1 10 to make different compromises for different classes of wireless devices in order to achieve as high spectrum efficiency as possible, while at the same time reserving transmission resources for a few selected wireless devices with special requirements, such as, for example, wireless devices requiring high reliability.

Action 202

The network node 1 10 transmits a grant message granting a group of wireless devices 121 -125 to perform uplink transmissions on a set of transmission resources in the wireless communications network 100 for a time period, T_grant, i . The grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices 121-125, for the set of transmission resources within the time period, Tgrant, 1 - In Fig. 1 , this transmission of a grant message is illustrated by the arrow 101 . The grant message may, in some cases, also be referred to as a token or uplink token indicating a grant to the group of wireless devices 121 -125.

By in this way sending an uplink transmission grant to more than one wireless device in the wireless communications network 100 and allocating sequential listening windows that allow these more than one wireless devices to take turn in listening to the set of transmission resources, the network node 1 10 ensures that the grant message is used by only one wireless device at a time. This may advantageously, for example, improve the utilization of an unlicensed spectrum by providing a flexible compromise between the fully scheduled uplink transmissions of LTE and fully-asynchronous uplink transmissions of WiFi. Here, it should be noted that the set of transmission resources may refer to any frequency and time resources, such as, one or more frequency bands, carriers, channels, etc., used by the wireless communications network 100.

Furthermore, a listening period may be defined as coherent time period or time span during which a wireless device measures received signals on the set of transmission resources. In some embodiments, the listening periods are non-overlapping search windows according to a Listen-Before-Talk, LBT, protocol. The LBT protocol may, for example, be the LBT protocol defined in ETSI EN 301 893. According to some embodiments, the listening periods may also be allocated by the network node 1 10 such that all wireless devices 121-125 have had a chance to listen one time each before the start of an LTE subframe. In that way, there is minimum waste of unnecessary transmissions to reserve the channel while waiting for next LTE subframe to start.

Optionally, in some embodiments, the network node 1 10 may increase the efficiency in the wireless communications network 100 by allowing data to be transmitted on an LTE symbol starting later than the LTE subframe starting time when the listening windows are allocated from the beginning of an LTE subframe. For example, user data may be transmitted from the 4^th LTE symbol and onwards. This may be signalled by the network node 1 10 in the grant message or potentially be predefined in the wireless

communications network 100.

In some embodiments, the grant message may comprise information indicating one or more of: the time period, T_grant,i ; an initial listening period for each of the wireless devices in the group of wireless devices 121 -125; a length of the listening periods; a time- interval between each listening period, and a maximum time period, Tma_X. T_max may indicate the longest time period for which a wireless device in the group of wireless devices 121 -125 are allowed to occupy the set of transmission resources for uplink transmissions. For example, by varying the number of wireless devices in the group of wireless devices 121-125 that receives the grant message and the time validity of the grant message, i.e. the time period T_grant,i , the network node 1 10 may assure that if there is at least one wireless device in the group of wireless devices 121 -125 that received the grant message that does not have a nearby interferer occupying the set of transmission resources, then that at least one wireless device may utilize the grant message for its uplink transmissions.

In some embodiments, the network node 1 10 may transmit at least a second grant message granting at least a second group of wireless devices 126-129 to perform uplink transmissions on at least a second set of transmission resources in the wireless communications network 100 for at least a second time period, T_grant, 2- The at least second grant message indicates sequentially allocated listening periods to the wireless devices in the at least second group of wireless devices 126-129, for the second set of transmission resources within the at least second time period, T_grant, 2- In Fig. 1 , this transmission of a grant message is illustrated by the arrow 102. Here, it should be noted that the second set of transmission resources also may refer to any frequency and time resources, such as, one or more frequency bands, carriers, channels, etc., used by the wireless communications network 100; however, this second set of transmission resources are different transmission resources than the set of transmission resources used by the group of wireless devices 121-125. In other words, the network node 1 10 may issue several grant messages in parallel associated with different sets of scheduled transmission resources. Hence, advantageously, multiple different groups of wireless devices may be addressed in the wireless communications network 100. Note that although only two groups of wireless devices, i.e. the group of wireless devices 121-125 and the group of wireless devices 126-129, are shown in Fig. 1 , any number of groups of wireless devices 5 in the wireless communications network 100 may be addressed by the embodiments described herein.

Action 203

Optionally, after transmitting the grant message in Action 202, the network node

10 1 10 may receive at least one uplink transmission on the set of transmission resources from at least one wireless device, such as, e.g. wireless device 121 , in the group of wireless devices 121-125 during the time period, T_grant, In Fig. 1 , this uplink transmission illustrated by the arrow 103.

This means that if one of the wireless devices in the group of wireless devices that

15 has received the transmitted grant message in Action 202 is comprised in the group of wireless device for which the grant message is issued, then this wireless device may transmit an uplink transmission to the network node 1 10 following one of its allocated listening window, e.g. based on constraints as described below in the embodiments of the wireless device 121. It also means that multiple non-colliding uplink transmissions from

20 different wireless devices in the group of wireless devices 121-125 may be received

during the time period, T_grant, i■

In some embodiments, the network node 1 10 may receive at least one uplink transmission on the at least second set of transmission resources from at least one wireless device, such as, e.g. wireless device 126, in the at least second group of wireless

25 devices 126-129 during the at least second time period, T_grant, 2- In Fig. 1 , this uplink

transmission illustrated by the arrow 104.

In some embodiments, the network node 1 10 may receive information indicating that at least one wireless device, e.g. wireless device 121 , will perform at least one uplink transmission on the set of transmission resources within the time period, T_grant, i■ In this

30 case, upon receiving the at least one uplink transmission, the network node 1 10 may identify the sender as the at least one wireless device, e.g. the wireless device 121 , based on said information. This means that instead of just starting to transmit uplink data, a wireless device may transmit a signal, for example, a specific sequence, indicator or message, to indicate that the wireless device intend to occupy the set of transmission

35 resources The signal may be advantageously used by the network node 1 10 to identify which wireless device it is that is actually using the grant message, and thereby simplify the detection and reception of the uplink data transmissions.

In some embodiments, the network node 100 may transmit the grant message on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network 100. This may be performed while the set of transmission resources on which the uplink transmissions are received forms part of an unlicensed spectrum in the wireless communications network 100. This may, for example, occur when LTE-LAA is supported in the wireless communications network 100. Optionally, the network node 100 may transmit the grant message on a set of transmission resources which forms part of an unlicensed spectrum in the wireless communication network 100.

Furthermore it should also be noted that, in some embodiments, the network node 1 10 may use spatial separation, e.g. MuMIMO techniques, in order to detect simultaneous uplink transmissions from two different wireless devices in a group of wireless devices, such as, e.g. the group of wireless devices 121-125 in Fig.1. This may be advantageous in case one of the wireless device in the group of wireless device fails to detect that another wireless device in the group of wireless devices is using the same grant message. This may occur, for example, in case there is a certain distance between the wireless devices in the group of wireless devices 121-125 in Fig.1 . This scenario may also be assisted in the wireless communications network 100 by having an uplink transmission resources allocation that facilitate uplink MIMO transmissions.

Example of embodiments of a method performed by wireless device 121 for enabling uplink transmissions in a wireless communications network 100 will now be described with reference to the flowchart depicted in Fig 3. Fig 3 is an illustrated example of actions or operations which may be taken by a wireless device 121 in the wireless communication network 100. The method may comprise the following actions.

Action 301

The wireless device 121 receives a grant message granting a group of wireless devices 121 -125 to perform uplink transmissions on a set of transmission resources in the wireless communications network 100 for a time period T_grant, i - Here, the wireless device 121 is comprised in the group of wireless devices 121-125 and the grant message indicates at least one allocated listening period to the wireless device 121 for the set of transmission resources within the time period T_grant, i . In some embodiments, the grant message comprise information indicating one or more of: the time period T_grant_,i , an initial listening period for the wireless device 121 , a length of the listening periods, a time-interval between each listening period, and a maximum time period Tmax for which the wireless device 121 is allowed to occupy the set of transmission resources for uplink transmissions.

In some embodiments, the length of the listening periods and/or the maximum time period T_max is preconfigured in the wireless device 121. This means that these parameters may be set or configured in the wireless device 12 before receiving the grant message.

Action 302

After the reception in Action 301 , the wireless device 121 may transmit an uplink transmission on the set of transmission resources when detecting that the set of transmission resources is not occupied for one of the at least one allocated listening periods. This means that the wireless device 121 may sense the channel, i.e. measure on the set of transmission resources according to an LBT protocol, during each allocated listening period in order to determine whether or not the set of transmission resources are free for the wireless device 121 to perform an uplink transmission on.

In some embodiments, the wireless device 121 may detect that the set of transmission resources is not occupied for an allocated listening period by determining that received signal power on the set of transmission resources for the allocated listening period is below a determined threshold level. This means that the wireless device 12 may determine whether or not the received signal energy on the set of transmission resources are below a certain threshold level. One example of a threshold level in the LBT protocol is -62 dBm.

Optionally, the wireless device 121 may detect that the set of transmission resources is not occupied for an allocated listening period by receiving information indicating that another wireless device in the group of wireless devices 121-125 will perform an uplink transmission on the set of transmission resources within the time period Tgrant, 1 - Hence, the wireless device 121 may be informed that another wireless device will occupy the set of transmission resources and may defer its uplink transmission until its next allocated listening window or for the entire uplink transmission duration. Furthermore, in some embodiments, the wireless device 121 may also transmit, before the uplink transmission, information indicating that the wireless device 121 will perform at least one uplink transmission on the set of transmission resources within the time period T_grant_, i - Hence, the wireless device 121 may make other wireless devices in the wireless communications network 100 aware that it will occupy the set of transmission resources, so that the other wireless devices in the wireless communications network 100 may defer their uplink transmissions until their next allocated listening windows, respectively, or for the entire uplink transmission duration. The latter specially makes sense for LTE since LTE transmissions are in the order of milliseconds, e.g. 1-4 ms, and a listening period may be short as a few tenths of microseconds, με.

One advantage of receiving or transmitting this information is that the signal may be designed so as to be easily detectable by the wireless device 121 or other wireless devices compared to, for example, detecting regular uplink LTE transmission signals. This signal may be designed like a preamble which indicates that the set of transmission resources are occupied. This signal may be comparable with the preamble that exists today in WiFi.

Further, it should be noted that this information also may be made to indicate to other wireless devices which grant message that the wireless device 121 is using. Hence, frequency selective scheduling according different grant messages may be enabled.

Furthermore, in some embodiments, the wireless device 121 may transmit the uplink transmission until the end of the time period T_grant, i , or until a maximum time period T_max expires. This means that the wireless device 121 may, for example, run the LBT protocol for each allocated listening window until it finds an uplink transmission opportunity or reaches the time validity of the grant, i.e. T_max expires.

Also, in some embodiments, the grant message may be received by the wireless device 121 on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network 100. In this case, the set of transmission resources on which the uplink transmissions are transmitted by the wireless device 121 may form part of an unlicensed spectrum in the wireless communications network 100. Optionally, the grant message may be received by the wireless device 121 on a set of transmission resources which forms part of an unlicensed spectrum in the wireless communication network 100.

Fig. 4 shows a signaling scheme illustrating an example of signaling according to embodiments of the network node 1 10 and the wireless device 121 -123 in the wireless communications network 100. In this example, the wireless devices 121 -123 form a group of wireless devices to which the network node 1 10 has transmitted a grant message for the time period T_grani as described in the embodiments above. For the sake of simplicity, it is here assumed that the wireless device 121 -123 are configured to perform channel sensing according to the LBT protocol. It should also be noted that the listening periods, denoted LBT in Fig. 4, are typically much shorter that the uplink transmission times, denoted UL DATA in Fig. 4, but for the sake of clarity the proportions of the listening periods are exaggerated in Fig. 4.

The wireless device 121 has been allocated a listening window starting at time t₀. During the listening window, the wireless device 121 detects a signal energy, e.g. a received signal power, which is above its determined threshold level, e.g. - 62dBm.

Hence, the wireless device 121 defers any potential uplink transmissions until its next allocated listening window; in other words, the wireless device 121 aborts the LBT after the end of the listening window at ti without finding an uplink transmission opportunity.

At time t|, a listening window allocated to the wireless device 123 starts. During the listening window, the wireless device 123 detects that the signal energy is below its determined threshold level and that there is no concurrent transmission performed by the other wireless devices 121 , 122. Thus, at time t₂, the wireless device 123 performs an uplink transmission, i.e. transmit UL data, until the maximum time period T_max is reached at time t₅. It should be noted that the uplink transmission may be performed after an assigned back-off time has expired. The uplink transmission is received by the network node 1 10 which may identify the wireless device 123 as the transmitter, and start decoding the uplink data from the wireless device 123.

At time t₂, a listening window allocated to the wireless device 122 starts. During the listening window, the wireless device 122 detects that the signal energy is below its determined threshold level, but that there is a concurrent transmission performed by the wireless devices 123. For example, the concurrent transmission may be detected by receiving a signal from the wireless device 123 indicating that the wireless device 123 will perform an uplink transmission. Hence, the wireless device 121 defers any potential uplink transmissions until its next allocated listening window or until the expected transmission for the wireless device 123 has ended; in other words, the wireless device 122 aborts the LBT after the end of the listening window at without finding an uplink transmission opportunity.

The wireless devices 121 , 122 will continue to find the concurrent transmission of the wireless device 123 until the maximum time period T_max expires at time t_5.

At time t₅, another listening window allocated to the wireless device 122 starts. During the listening window, the wireless device 121 detects a signal energy which is above its determined threshold level. Hence, the wireless device 122 defers any potential uplink transmissions until its next allocated listening window.

At time t₆, another listening window allocated to the wireless device 121 starts. During the listening window, the wireless device 121 detects that the signal energy is below its determined threshold level and that there is no concurrent transmission performed by the other wireless devices 122, 123. Thus, at time t₇, the wireless device 123 performs an uplink transmission. The uplink transmission may be performed after an assigned back-off time has expired, and either until the maximum time period T_max is reached or until the the time period T expires. The uplink transmission is received by the network node 1 10 which may identify the wireless device 121 as the transmitter, and start decoding the uplink data from the wireless device 121.

This example illustrate how a balance may be achieve for a combined LTE/WiFi network, i.e. a wireless communications network using both a licensed and an unlicensed frequency spectrum. In case the grant message is sent to only one wireless device in the wireless communications network 100 and T_max is set to a single subframe, then this will mimic the regular LTE UL scheduling mechanism; while in case the grant message is sent to every wireless device in the wireless communications network 100 and the T_max is set to an infinite number of subframes, then this will mimic the regular WiFi UL scheduling mechanism. Hence, it should be noted that by varying and setting the parameters described in the embodiments above, these two mechanisms may be balanced with respect to each other in order to find the most efficient use of the frequency spectrum in the wireless communications network 100.

To perform the method actions in the network node 1 10 for enabling uplink transmissions in a wireless communications network 100, the network node 1 10 may comprise the following arrangement depicted in Fig 5. Fig 5 shows a schematic block diagram of embodiments of a network node 1 10. The embodiments of the network node 1 10 described herein may be considered as independent embodiments or may be considered in any combination with each other to describe non-limiting examples of the example embodiments described herein.

The network node 1 10 may comprise a processing circuitry 510, a memory 520 and at least one antenna (not shown). The processing circuitry 510 may comprise a receiving module 511 and a transmitting module 512. The receiving module 51 1 and the transmitting module 512 may comprise Radio Frequency, RF, circuitry and baseband processing circuitry. The receiving module 51 1 and the transmitting module 512 may also form part of a transceiver. In particular embodiments, some or all of the functionality described above as being performed by the network node 1 10 may be provided by the processing circuitry 510 executing instructions stored on a computer-readable medium, such as the memory 520 shown in Fig. 5. Alternative embodiments of the wireless device 5 121 may comprise additional components, such as, the determining module 513 and the identification module 514, responsible for providing its functionality necessary to support the embodiments described herein.

The network node 1 10 or processing circuitry 510 is configured to, or may comprise the transmitting module 512 configured to, transmit a grant message granting a0 group of wireless devices 121-125 to perform uplink transmissions on a set of

transmission resources in the wireless communications network 100 for a time period Tgrant, 1 , wherein the grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices 121-125 for the set of transmission resources within the time period T_grant, 1.

5 In some embodiments, the network node 1 10 or processing circuitry 510 may be configured to, or may comprise the receiving module 51 1 being configured to, receive at least one uplink transmission on the set of transmission resources from at least one wireless device in the group of wireless devices 121-125 during the time period T_grant, i . In some embodiments, the network node 1 10 or processing circuitry 510 may be configured0 to, or may comprise the determining module 513 being configured to, determine the group of wireless devices 121-125 based on a selection criteria, wherein the selection criteria is based on one or more of: the service requirements of the wireless devices in the group of wireless devices 121-125, the capabilities of the wireless devices in the group of wireless devices 121 -125, and measurement reports from the wireless devices in the group of5 wireless devices 121-125.

In some embodiments, the grant message comprise information indicating one or more of: the time period T_grant,i , an initial listening period for each of the wireless devices in the group of wireless devices 121 -125, a length of the listening periods, a time-interval between each listening period, and a maximum time period T_max for which a wireless0 device in the group of wireless devices 121-125 is allowed to occupy the set of

transmission resources for uplink transmissions.

Also, in some embodiments, the network node 1 10 or processing circuitry 510 may be configured to, or may comprise the receiving module 51 1 being configured to, receive information indicating that at least one wireless device 121 will perform at least one uplink5 transmission on the set of transmission resources within the time period T_grant, i - In this case, the network node 1 10 or processing circuitry 510 may also be configured to, or may comprise the identification module 514 being configured to, upon receiving the at least one uplink transmission, identify the sender as the at least one wireless device 121 based on said information.

In some embodiments, the network node 1 10 or processing circuitry 510 may be configured to, or may comprise the transmitting module 51 1 being configured to, transmit at least a second grant message granting at least a second group of wireless devices 126-130to perform uplink transmissions on at least a second set of transmission resources in the wireless communications network 100 for at least a second time period Tgrant, 2, wherein the at least second grant message indicates sequentially allocated listening periods to the wireless devices in the at least second group of wireless devices 126-130 for the second set of transmission resources within the at least second time period T_grant, 2- In this case, the network node 1 10 or processing circuitry 510 may also be configured to, or may comprise the receiving module 51 1 being configured to, receive at least one uplink transmission on the at least second set of transmission resources from at least one wireless device in the at least second group of wireless devices 126-130 during the at least second time period T_{g ran}t, 2- Here, the network node 1 10 or processing circuitry 510 may further be configured to, or may comprise the determining module 513 being configured to, determine the at least second group of wireless devices 126-130 based on at least a second selection criteria, wherein the at least second selection criteria is based on one or more of: the service requirements of the wireless devices in the at least second group of wireless devices 126-130, the capabilities of the wireless devices in the at least second group of wireless devices 126-130, and measurement reports from the wireless devices in the at least second group of wireless devices 126-130.

In some embodiments, the listening periods are non-overlapping search windows according to a Listen-Before-Talk, LBT, protocol.

Also, in some embodiments, the network node 1 10 or processing circuitry 510 may be configured to, or may comprise the transmitting module 51 1 being configured to, transmit the grant message on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network 100. In this case, the network node 1 10 or processing circuitry 510 may also be configured to, or may comprise the receiving module 51 1 being configured to, receive the uplink transmissions on a set of transmission resources which forms part of an unlicensed spectrum in the wireless communications network 100. Furthermore, the embodiments for enabling uplink transmissions in a wireless communications network 100 described above may be implemented through one or more processors, such as the processing circuitry 510 in the network node 1 10 depicted in Fig. 5, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 510 in the network node 1 10. The computer program code may e.g. be provided as pure program code in the network node 1 10 or on a server and downloaded to the network node 1 10. Thus, it should be noted that the modules of the network node 1 10 may in some embodiments be implemented as computer programs stored in memory, e.g. in the memory modules 520 in Figure 5, for execution by processors, e.g. the processing modules 510 of Figure 5.

Those skilled in the art will also appreciate that the processing circuitry 510 and the memory 520 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processing circuitry 520 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system- on-a-chip (SoC).

To perform the method actions in the wireless device 121 for enabling uplink transmissions in a wireless communications network 100, the wireless device 121 may comprise the following arrangement depicted in Fig 6. Fig 6 shows a schematic block diagram of embodiments of a wireless device 121. The embodiments of the wireless device 121 described herein may be considered as independent embodiments or may be considered in any combination with each other to describe non-limiting examples of the example embodiments described herein.

The wireless device 121 may comprise processing circuitry 610, a memory 620 and at least one antenna (not shown). The processing circuitry 610 may also comprise a receiving module 611 and a transmitting module 612. The receiving module 61 1 and the transmitting module 612 may comprise Radio Frequency, RF, circuitry and baseband processing circuitry. The receiving module 61 1 and the transmitting module 612 may also form part of a transceiver. In particular embodiments, some or all of the functionality described above as being performed by the wireless device 121 may be provided by the processing circuitry 610 executing instructions stored on a computer-readable medium, such as, e.g. the memory 620 shown in Fig. 6. Alternative embodiments of the wireless device 121 may comprise additional components, such as, the detecting module 613, responsible for providing its functionality necessary to support the embodiments described herein.

The wireless device 121 or processing circuitry 610 is configured to, or may comprise the receiving module 61 1 configured to, receive a grant message granting a group of wireless devices 121-125 to perform uplink transmissions on a set of transmission resources in the wireless communications network 100 for a time period Tgrant_, 1 , wherein the wireless device 121 is comprised in the group of wireless devices 121 -125 and the grant message indicates at least one allocated listening period to the wireless device 121 for the set of transmission resources within the time period T_grant_, i . In some embodiments, the wireless device 121 or processing circuitry 610 may further be configured to, or may comprise the transmitting module 612 being configured to, transmit an uplink transmission on the set of transmission resources when detecting that the set of transmission resources is not occupied for one of the at least one allocated listening periods.

Also, in some embodiments, the network node 1 10 or processing circuitry 510 may be configured to, or may comprise the detecting module 613 being configured to, detect that the set of transmission resources is not occupied for an allocated listening period by determining that received signal power on the set of transmission resources for the allocated listening period is below a determined threshold level, or by receiving information indicating that another wireless device in the group of wireless devices 121- 125 will perform an uplink transmission on the set of transmission resources within the time period T_grant, i -

In some embodiments, the grant message comprise information indicating one or more of: the time period T_grant_,i , an initial listening period for the wireless device 121 , a length of the listening periods, a time-interval between each listening period, and a maximum time period Tmax for which the wireless device 121 is allowed to occupy the set of transmission resources for uplink transmissions. In some embodiments, the length of the listening periods and/or the maximum time period T_max is preconfigured in the wireless device 121. In some embodiments, the wireless device 121 or processing circuitry 610 may further be configured to, or may comprise the transmitting module 612 being configured to, transmit the uplink transmission until the end of the time period T_grant, i , or until a maximum time period Tmax expires. Also, in some embodiments, the wireless device 121 or processing circuitry 610 may further be configured to, or may comprise the transmitting module 612 being configured to, transmit, before the uplink transmission, information indicating that the wireless device 121 will perform at least one uplink transmission on the set of transmission resources within the time period T_grant, i -

In some embodiments, the wireless device 121 or processing circuitry 610 is configured to, or may comprise the receiving module 61 1 configured to, receive the grant message on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network 100. Here, in some embodiments, the wireless device 121 or processing circuitry 610 may further be configured to, or may comprise the transmitting module 612 being configured to, transmit uplink transmissions on a set of transmission resources which forms part of an unlicensed spectrum in the wireless communications network 100.

Furthermore, the embodiments for enabling uplink transmissions in a wireless communications network 100 described above may be implemented through one or more processors, such as the processing circuitry 610 in the wireless device 121 depicted in Fig. 6, together with computer program code for performing the functions and actions of the embodiments herein. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code or code means for performing the embodiments herein when being loaded into the processing circuitry 610 in the wireless device 121. The computer program code may e.g. be provided as pure program code in the wireless device 121 or on a server and downloaded to the wireless device 121. Thus, it should be noted that the modules of the wireless device 121 may in some embodiments be implemented as computer programs stored in memory, e.g. in the memory modules 620 in Figure 6, for execution by processors, e.g. the processing modules 610 of Figure 6.

Those skilled in the art will also appreciate that the processing circuitry 610 and the memory 620 described above may refer to a combination of analog and digital circuits, and/or one or more processors configured with software and/or firmware, e.g. stored in a memory, that when executed by the one or more processors such as the processing circuitry 620 perform as described above. One or more of these processors, as well as the other digital hardware, may be included in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system- on-a-chip (SoC).

The description of the example embodiments provided herein have been presented for purposes of illustration. The description is not intended to be exhaustive or to limit example embodiments to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various alternatives to the provided embodiments. The examples discussed herein were chosen and described in order to explain the principles and the nature of various example embodiments and its practical application to enable one skilled in the art to utilize the example embodiments in various manners and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and computer program products. It should be appreciated that the example embodiments presented herein may be practiced in any combination with each other.

It should be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed and the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the example embodiments may be implemented at least in part by means of both hardware and software, and that several "means", "units" or "devices" may be represented by the same item of hardware.

It should also be noted that the various example embodiments described herein are described in the general context of method steps or processes, which may be implemented in one aspect by a computer program product, embodied in a computer- readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. A computer-readable medium may include removable and non-removable storage devices including, but not limited to, Read Only Memory (ROM), Random Access Memory (RAM), compact discs (CDs), digital versatile discs (DVD), etc. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

The embodiments herein are not limited to the above described preferred embodiments. Various alternatives, modifications and equivalents may be used.

Therefore, the above embodiments should not be construed as limiting.

Abbreviations

3GPP Third Generation Partnership Project

UMTS Universal Mobile Telecommunications System

GSM Global System for Mobile Communications

WCDMA Wideband Code Division Multiple Access

HSPA High Speed Packet Access

LTE Long Term Evolution

RAN Radio Access Network

UTRAN UMTS terrestrial RAN

E-UTRAN Evolved Universal Terrestrial Radio Access Network

WLAN Wireless Local Access Network

LTE Long Term Evolution

UE User Equipment

AIFS Arbitration Inter-Frame Spacing

AP Access point

DL Downlink

HARQ Hybrid automated repeat request

LAA-LTE License-Assisted Access via LTE

LTE-U LTE in Unlicensed Band

LBT Listen-Before-Talk

MOT Maximum Occupancy Time

P-cell Primary Cell

PDSCH Physical Downlink Shared Channel

S-Cell Secondary Cell

SIFS Short Inter-Frame Spacing

SF Subframe

STA Station

UL Uplink

VoIP Voice over IP

Claims

1 . A method performed by a network node (1 10) for enabling uplink transmissions in a wireless communications network (100), the method comprising

transmitting (202) a grant message granting a group of wireless devices (121-125) to perform uplink transmissions on a set of transmission resources in the wireless communications network (100) for a time period (T_grant, i), wherein the grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices (121 -125) for the set of transmission resources within the time period (T_grant, i).

2. The method according to claim 1 , further comprising

receiving (203) at least one uplink transmission on the set of transmission resources from at least one wireless device (121) in the group of wireless devices (121-125) during the time period (T_grant, i).

3. The method according to claim 1 or 2, further comprising

determining (201) the group of wireless devices (121-125) based on a selection criteria, wherein the selection criteria is based on one or more of:

- the service requirements of the wireless devices in the group of wireless devices (121-125);

- the capabilities of the wireless devices in the group of wireless devices (121- 125); and

- measurement reports from the wireless devices in the group of wireless

devices (121-125).

4. The method according to any of claims 1-3, wherein the grant message comprise information indicating one or more of:

- the time period (T_grant,i),

- an initial listening period for each of the wireless devices in the group of wireless devices (121 -125),

- a length of the listening periods,

- a time-interval between each listening period, and

- a maximum time period (T_max) for which a wireless device in the group of wireless devices (121 -125) is allowed to occupy the set of transmission resources for uplink transmissions. The method according to any of claims 1-4, further comprising receiving information indicating that at least one wireless device (121) will perform at least one uplink transmission on the set of transmission resources within the time period (T_grant, i); and, upon receiving the at least one uplink transmission, identifying the sender as the at least one wireless device (121) based on said information.

The method according to any of claims 1-5, further comprising transmitting at least a second grant message granting at least a second group of wireless devices (126-130) to perform uplink transmissions on at least a second set of transmission resources in the wireless communications network (100) for at least a second time period (T_grant, 2) , wherein the at least second grant message indicates sequentially allocated listening periods to the wireless devices in the at least second group of wireless devices (126-130) for the second set of transmission resources within the at least second time period (Tg_rant, 2) ; and receiving at least one uplink transmission on the at least second set of transmission resources from at least one wireless device (126) in the at least second group of wireless devices (126-130) during the at least second time period

(Tgrant,

The method according to claim 6, further comprising determining the at least second group of wireless devices (126-130) based on at least a second selection criteria, wherein the at least second selection criteria is based on one or more of:

- the service requirements of the wireless devices in the at least second group of wireless devices (126-130);

- the capabilities of the wireless devices in the at least second group of wireless devices (126-130); and

measurement reports from the wireless devices in the at least second group of wireless devices (126-130).

The method according to any of claims 1-7, wherein the listening periods are non- overlapping search windows according to a Listen-Before-Talk, LBT, protocol. The method according to any of claims 1-8, wherein the grant message is transmitted on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network (100), and wherein the set of transmission resources on which the uplink transmissions are received forms part of an unlicensed spectrum in the wireless communications network (100).

10. A network node (1 10) for enabling uplink transmissions in a wireless

communications network (100), the network node (1 10) being configured to

transmit a grant message granting a group of wireless devices (121-125) to perform uplink transmissions on a set of transmission resources in the wireless communications network (100) for a time period (T_grant, i), wherein the grant message indicates sequentially allocated listening periods to the wireless devices in the group of wireless devices (121 -125) for the set of transmission resources within the time period (T_grant, i).

1 1 . The network node (1 10) according to claim 10, further configured to receive at least one uplink transmission on the set of transmission resources from at least one wireless device (121) in the group of wireless devices (121-125) during the time period (T_grant, i).

12. The network node (1 10) according to claim 10 or 1 1 , further configured to

determine the group of wireless devices (121 -125) based on a selection criteria, wherein the selection criteria is based on one or more of:

- measurement reports from the wireless devices in the group of wireless

devices (121-125).

13. The network node (1 10) according to any of claims 10-12, wherein the grant message comprise information indicating one or more of:

- the time period (T_grant_,i),

- an initial listening period for each of the wireless devices in the group of wireless devices (121 -125), - a length of the listening periods,

- a time-interval between each listening period, and

- a maximum time period (T_max) for which a wireless device in the group of wireless devices (121 -125) is allowed to occupy the set of transmission resources for uplink transmissions.

14. The network node (1 10) according to any of claims 10-13, further configured to receive information indicating that at least one wireless device (121) will perform at least one uplink transmission on the set of transmission resources within the time period (T_grant, i) , and to, upon receiving the at least one uplink transmission, identify the sender as the at least one wireless device (121) based on said information.

15. The network node (1 10) according to any of claims 10-14, further configured to transmit at least a second grant message granting at least a second group of wireless devices (126-130) to perform uplink transmissions on at least a second set of transmission resources in the wireless communications network (100) for at least a second time period (T_grant, 2) , wherein the at least second grant message indicates sequentially allocated listening periods to the wireless devices in the at least second group of wireless devices (126-130) for the second set of transmission resources within the at least second time period (T_grant, 2) , and receive at least one uplink transmission on the at least second set of transmission resources from at least one wireless device (126) in the at least second group of wireless devices (126-130) during the at least second time period (T_grant, 2) -

16. The network node (1 10) according to claim 15, further configured to determine the at least second group of wireless devices (126-130) based on at least a second selection criteria, wherein the at least second selection criteria is based on one or more of:

17. The network node (1 10) according to any of claims 10-16, wherein the listening periods are non-overlapping search windows according to a Listen-Before-Talk, LBT, protocol.

18. The network node (1 10) according to any of claims 10-17, wherein the grant message is transmitted on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network (100), and wherein the set of transmission resources on which the uplink transmissions are received forms part of an unlicensed spectrum in the wireless communications network

(100).

19. A method performed by a wireless device (121) for enabling uplink transmissions in a wireless communications network (100), the method comprising

receiving (301) a grant message granting a group of wireless devices (121 -

125) to perform uplink transmissions on a set of transmission resources in the wireless communications network (100) for a time period (T_grant, i), wherein the wireless device (121) is comprised in the group of wireless devices (121-125) and the grant message indicates at least one allocated listening period to the wireless device (121) for the set of transmission resources within the time period (T_grant, i).

20. The method according to claim 19, further comprising

transmitting (302) an uplink transmission on the set of transmission resources when detecting that the set of transmission resources is not occupied for one of the at least one allocated listening periods.

21 . The method according to claim 19 or 20, further comprising detecting that the set of transmission resources is not occupied for an allocated listening period by determining that received signal power on the set of transmission resources for the allocated listening period is below a determined threshold level, or by receiving information indicating that another wireless device in the group of wireless devices (121-125) will perform an uplink transmission on the set of transmission resources within the time period (T_grant, i).

22. The method according to any of claims 19-21 , wherein the grant message comprise information indicating one or more of:

- the time period (T_grant,i),

- an initial listening period for the wireless device (121),

- a length of the listening periods,

- a time-interval between each listening period, and

- a maximum time period (T_max) for which the wireless device (121) is allowed to occupy the set of transmission resources for uplink transmissions.

23. The method according to claim 22, wherein the length of the listening periods and/or the maximum time period (Tma_X) is preconfigured in the wireless device (121).

24. The method according to any of claims 19-23, wherein the uplink transmission is transmitted until the end of the time period (T_grant, i) or until a maximum time period (Τ^_χ) expires.

25. The method according to any of claims 19-24, further comprising transmitting, before the uplink transmission, information indicating that the wireless device (121) will perform at least one uplink transmission on the set of transmission resources within the time period (T_grant_, i).

26. The method according to any of claims 19-25, wherein the grant message is received on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network (100), and wherein the set of transmission resources on which the uplink transmissions are transmitted forms part of an unlicensed spectrum in the wireless communications network (100).

27. A wireless device (121) for enabling uplink transmissions in a wireless

communications network (100), the wireless device (121) being configured to receive a grant message granting a group of wireless devices (121-125) to perform uplink transmissions on a set of transmission resources in the wireless communications network (100) for a time period (T_grant_, i), wherein the wireless device (121) is comprised in the group of wireless devices (121 -125) and the grant message indicates at least one allocated listening period to the wireless device (121) for the set of transmission resources within the time period (T_grant, i)-

28. The wireless device (121) according to claim 27, further configured to transmit an uplink transmission on the set of transmission resources when detecting that the set of transmission resources is not occupied for one of the at least one allocated listening periods.

29. The wireless device (121) according to claim 27 or 28, further configured to detect that the set of transmission resources is not occupied for an allocated listening period by determining that received signal power on the set of transmission resources for the allocated listening period is below a determined threshold level, or by receiving information indicating that another wireless device in the group of wireless devices (121-125) will perform an uplink transmission on the set of transmission resources within the time period (T_grant, i)-

30. The wireless device (121) according to any of claims 27-29, wherein the grant message comprise information indicating one or more of:

- the time period (T_grant_,i),

- an initial listening period for the wireless device (121),

- a length of the listening periods,

- a time-interval between each listening period, and

31 . The wireless device (121) according to claim 30, wherein the length of the

listening periods and/or the maximum time period (T_max) is preconfigured in the wireless device (121).

32. The wireless device (121) according to any of claims 27-31 , wherein the uplink transmission is transmitted until the end of the time period (T_grant_, i) or until a maximum time period (T_max) expires.

33. The wireless device (121) according to any of claims 27-32, further configured to transmit, before the uplink transmission, information indicating that the wireless device (121) will perform at least one uplink transmission on the set of transmission resources within the time period (T_grant, i)-

34. The wireless device (121) according to any of claims 27-33, wherein the grant message is received on a set of transmission resources which forms part of a licensed spectrum in the wireless communication network (100), and wherein the set of transmission resources on which the uplink transmissions are transmitted forms part of an unlicensed spectrum in the wireless communications network (100).

35. A computer program product, comprising instructions which, when executed on at least one processor (410; 510), cause the at least one processor (410; 510) to carry out the method according to any of claims 1 -9 or 19-26. 36. A carrier containing the computer program product according to claim 35, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer- readable storage medium.