FIELD

[0001] Embodiments of the present invention relate in general to communication networks. More specifically, embodiments of the present invention relate to uplink grant- free transmissions in such networks.

BACKGROUND

[0002] Grant-free transmissions may be used in various wireless communication networks to improve latency in the uplink direction. As an example, in Long Term Evolution, LTE, networks Semi-Persistent Scheduling, SPS, may be used to provide grant-free uplink transmissions. Using SPS, resources may be configured for a User Equipment, UE, with one grant so that one resource allocation is basically repeated according to a pre-configured periodicity. The UE may therefore transmit using the semi-persistently allocated resources without additional grants. Similar solution may be found at least from New Radio, NR specifications. Also, according to MulteFire and License Assisted Access, LAA, specifications grant-free uplink transmission may be used to reduce delay in unlicensed spectrum.

[0003] Traditionally, grant-free resources have been used for deterministic traffic but more recently it has become desirable to use grant-free transmission for sporadic traffic as well. However, sporadic traffic may lead to unused grant-free resources because conventional solutions do not enable reallocation of resources, if there are unused resources which are configured for grant-free transmissions. Collision avoidance on grant- free resources is also a challenge, if multiple UEs are configured for the same grant-free resource.

[0004] There is therefore a need for providing improved methods, apparatuses and computer programs for transmissions using grant-free resources, for allowing reallocation of configured grant-free resources for other transmissions, in case the grant-free resources are not used. At the same time there is a need to avoid collisions on grant-free resources as well, to enable configuring of multiple UEs for the same grant-free resource. SUMMARY OF THE INVENTION

[0005] According to some aspects, there is provided the subject-matter of the independent claims. Some embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present invention, there is provided a method comprising indicating to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, determining, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed and transmitting, depending on determining whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data to the network node.

[0007] According to a second aspect of the present invention, there is provided a method comprising determining, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, indicating, to the first terminal whether the use of the first set of grant-free resources configured for the first terminal is confirmed and receiving, depending on whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data from the first terminal.

[0008] According to a third aspect of the present invention, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to indicate to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, determine, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed and transmit, depending on determining whether the use of the first set of grant- free resources configured for the first terminal is confirmed, the data to the network node.

[0009] According to a fourth aspect of the present invention, there is provided an apparatus comprising at least one processing core, at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processing core, cause the apparatus at least to determine, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, indicate to the first terminal whether the use of the first set of grant-free resources configured for the first terminal is confirmed and receive, depending on whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data from the first terminal. [0010] According to a fifth aspect of the present invention, there is provided an apparatus comprising means for indicating to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, means for determining, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed and means for transmitting, depending on determining whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data to the network node.

[0011] According to a sixth aspect of the present invention, there is provided an apparatus comprising means for determining, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, means for indicating to the first terminal whether the use of the first set of grant-free resources configured for the first terminal is confirmed and means for receiving, depending on whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data from the first terminal.

[0012] According to a seventh aspect of the present invention, there is provided a non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least indicate to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, determine, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed and transmit, depending on determining whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data to the network node.

[0013] According to an eighth aspect of the present invention, there is provided a non-transitory computer readable medium having stored thereon a set of computer readable instructions that, when executed by at least one processor, cause an apparatus to at least determine, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, indicate to the first terminal whether the use of the first set of grant-free resources configured for the first terminal is confirmed and receive, depending on whether the use of the first set of grant- free resources configured for the first terminal is confirmed, the data from the first terminal.

[0014] According to a ninth aspect of the present invention, there is provided a computer program configured to cause the following to be performed, when executed by a computer: indicate to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, determine, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed and transmit, depending on determining whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data to the network node.

[0015] According to a tenth aspect of the present invention, there is provided a computer program configured to cause the following to be performed, when executed by a computer: determine, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal, indicate to the first terminal whether the use of the first set of grant-free resources configured for the first terminal is confirmed and receive, depending on whether the use of the first set of grant-free resources configured for the first terminal is confirmed, the data from the first terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGURE 1 illustrates a network scenario in accordance with at least some embodiments of the present invention;

[0017] FIGURE 2 illustrates a first example in accordance with at least some embodiments of the present invention;

[0018] FIGURE 3 illustrates a second example in accordance with at least some embodiments of the present invention;

[0019] FIGURE 4 illustrates an example apparatus capable of supporting at least some embodiments of the present invention;

[0020] FIGURE 5 illustrates a flow graph of a first method in accordance with at least some embodiments of the present invention;

[0021] FIGURE 6 illustrates a flow graph of a second method in accordance with at least some embodiments of the present invention. EMBODIMENTS

[0022] Utilization of grant-free resources may be improved by the procedures described herein. In more detail, a terminal may indicate to a network node that the terminal intends to transmit data using a grant-free resource configured for the terminal. In response, the network node may indicate to the terminal whether the use of the grant-free resource configured for the terminal is confirmed, or permitted. So even if multiple terminals would be configured for the grant-free resource, collisions on the configured grant-free resource may be avoided. Multiple UEs would not try to use the grant-free resource simultaneously, because the network node would not allow it. Moreover, the network node may reallocate the grant-free resource for other transmissions, if none of the terminals intends to transmit data using the grant-free resource.

[0023] FIGURE 1 illustrates an example system in accordance with at least some embodiments of the present invention. User Equipment, UE, 1 10, 120 and 130 may comprise, for example, a smartphone, a cellular phone, a Machine-to-Machine, M2M, node, machine-type communications node, an Internet of Things, loT, node, a car telemetry unit, a laptop computer, a tablet computer or, indeed, another kind of suitable user device or mobile station, i.e., a terminal. In the example system of FIGURE 1 , UEs 1 10, 120 and 130 may be attached to a cell of Base Station, BS, 140. BS 140 may be considered as a serving BS for UEs 1 10, 120 and 130. Air interface 1 15 between UE 1 10 and BS 140 may be configured in accordance with a Radio Access Technology, RAT, which both UE 1 10 and base station 140 are configured to support. Air interface 125 between BS 140 and UE 120, and air interface 135 between BS 140 and UE 130 may be configured similarly.

[0024] Examples of cellular RATs include Long Term Evolution, LTE, New Radio, NR, which is also known as fifth generation, 5G, and MulteFire. On the other hand, examples of non-cellular RATs include Wireless Local Area Network, WLAN, and Worldwide Interoperability for Microwave Access, WiMAX. Principles of the present disclosure are not limited to a specific RAT though. For example, in the context of LTE, BS 140 may be referred to as eNB while in the context NR, BS 140 may be referred to as gNB. Also, for example in the context of WLAN, BS 140 may be referred to as an access point. In general, BS 140 may be referred to as a network node. UEs 1 10, 120 and 130 may be similarly referred to as terminals in general. In any case, the present invention is not restricted to any particular wireless technology, but it may be exploited in any system which uses grant-free uplink transmissions. [0025] BS 140 may be connected, directly or via at least one intermediate node, with core network 150. Core network 150 may be, in turn, coupled with another network (not shown in FIGURE 1 ), via which connectivity to further networks may be obtained, for example via a worldwide interconnection network. BS 140 may be connected with at least one other BS as well via an inter-base station interface (not shown in FIGURE 1 ), even though in some embodiments the inter-base station interface may be absent. BS 140 may be connected, directly or via at least one intermediate node, with core network 150 or with another core network.

[0026] Grant-free resources may be used in various wireless networks, but transmissions using grant-free resources may be named differently in different contexts. For example, in the context of LTE Semi-Persistent Scheduling, SPS, may be seen as one form of grant-free resources. SPS may be used to reduce control channel overhead, especially in case of deterministic traffic, such as, Voice over IP, VoIP. Also, SPS may be used to support low latency communications. However, if the traffic is not deterministic, SPS may reserve resources for nothing and thereby incur unnecessary overhead due to unused SPS resources, which cannot be allocated for other traffic.

[0027] In case of NR, grant-free transmissions may be referred to as configured uplink grants. Grant-free transmissions may be referred to as grant-less uplink transmissions as well, which may be used to reduce the channel access delay at least in unlicensed spectrum. For example, in case of MulteFire the term Grant-less Uplink, GUL, may be used. In addition, in the context of License Assisted Access, LAA, grant-free transmissions may be referred to as Autonomous Uplink, AUL.

[0028] In general, it is desirable to reduce the probability of having unused grant-free resources, which may be an issue especially in case of sporadic traffic. One approach for reducing the probability of having unused grant-free resources may be to allow allocation of multiple terminals, e.g., UEs, for a certain grant-free resource. That is to say, multiple terminals may be configured for the same grant-free resource in an attempt to reduce overhead. Such an approach may comprise taking advantage of statistical multiplexing. However, allocating multiple terminals for a certain grant-free resource may create another problem, because if at least two terminals decide to transmit using the same resource, a collision may occur.

[0029] Currently it may be challenging, or even impossible in practice, to reallocate grant-free resources as, for example, grant-based uplink resources, even though sporadic traffic would cause unused resources. The challenge is that if conventional solutions are use, a BS does not know beforehand, i.e., a priori, whether uplink grant-free transmissions will take place. Thus, a configured set of grant-free resources, having a starting time, may be detected by the BS as unused only after the starting time. Therefore, the BS is not able to react to the situation in time and it will be too late to reallocate the configured set of grant- free resources, if it was not used.

[0030] The present invention hence aims to provide a mechanism which allows the BS to allocate a set of grant-free resources for multiple UEs, or terminals in general, while minimizing the likelihood of collision and enabling dynamic reallocation of the set of grant- free resources as a grant-based resource. According to some embodiments of the present invention, the BS may perform pre-emption of the grant-free uplink resource to avoid collisions. Also, the BS may reallocate the set of grant-free resources for another transmission, such as, for a grant-based transmission. An example of a grant-based transmission may be enhanced Mobile BroadBand, eMBB, transmission. The present invention also enables effective collision avoidance, even if frequency division multiplexing would be used on grant-free resources.

[0031] In the following, a process for grant-free uplink transmissions will be described. Principles described herein are equally applicable to grant-free uplink transmissions from UEs 1 10, 120 and 130 to BS 140. Generally speaking, UEs 1 10, 120, 130 may be referred to as terminals, while BS 140 may be referred to as a network node, possibly serving the terminals via air interface.

[0032] In some embodiments of the present invention, there may be a configured first set of grant-free resources for a UE. According to the embodiments of the present invention the first set of grant-free resources may also refer to a group of grant-free resources. The configured first set of grant-free resources may be associated with a certain frequency block, or multiple frequency blocks, and it may have a starting time and length. The first set of grant-free resources may be pre-configured by a BS.

[0033] Then, if the UE has data to transmit using the first set of grant-free resources, it may transmit a pre-emption beacon signal to the BS before the start of the configured first set of grant-free resources. The pre-emption beacon signal may be referred to as a first message. The first message, i.e., the pre-emption beacon signal may be transmitted to request for confirmation, or permission, to use the configured set of grant-free resources. The pre-emption beacon signal may be referred to as an apriori (in advance) indication that the UE intends to transmit data using the configured first set of grant-free resources. The UE in question may be referred to as a first terminal in some embodiments of the present invention.

[0034] The pre-emption beacon signal may include a UE identification, which would allow the BS to detect which UE intends to transmit data using the configured set of grant- free resources. For example, the pre-emption beacon signal may work as a kind of early preamble and comprise, e.g., a Demodulation Reference Signal, DMRS, and potentially other signals. Time and frequency resources that are used for the transmission of the pre- emption beacon signal may be a part of the grant-free configuration provided to the UE, by the BS. Also, in some embodiments of the present invention there may be one or more sets of grant-free resources configured for the same UE, and the UE may be assumed to use only one resource set per grant-free transmission. Thus, the BS may decide to switch some of the UEs from one resource set to another, based on all the received pre-emption signals, to minimize collisions.

[0035] Alternatively, in some embodiments of the present invention, the UE may indicate that it intends to transmit data using the configured first set of grant-free resources by not transmitting the pre-emption beacon signal. Thus, in that case the BS may detect lack of the pre-emption beacon signal and determine, based on non-detection of the pre- emption beacon, that the UE intends to transmit data using the configured set of grant-free resources. Non-detection of the beacon may be therefore also referred to as an indication that the UE intends to transmit data using the configured set of grant-free resources. Thus, according to this alternative the UE may transmit the pre-emption beacon signal only if it does not intend to use the first set of grant-free resources configured for it. Hence, the alternative may be seen as an alternative use of the pre-emption signal.

[0036] That is to say, the pre-emption beacon signal, or alternatively lack of it, may indicate a priori, i.e., before the configured first set of grant-free resources in time, to the BS that the UE intends to initiate a first grant-free transmission using the configured first set of grant-free resources. The pre-emption beacon signal, or alternatively lack of it, may be seen as a request to confirm whether the first set of grant-free resources can be used. Possibly, the pre-emption beacon signal may be received by other UEs and/or other BSs as well. The pre-emption beacon signal may be broadcasted or multicasted to a group of UEs.

[0037] In some embodiments of the present invention, the BS may detect the pre- emption beacon signal, or alternatively lack of it, before the starting time of the configured first set of grant-free resources. The BS may therefore determine based on the received pre-emption beacon signal, or alternatively lack of it, that the UE intends to transmit data using the first set of grant-free resources configured for the UE.

[0038] In addition, the BS may also determine whether the use of the first set of grant- free resources configured for the terminal can be confirmed. As an example, this determination may be based, at least partly, on checking if the set of grant-free resources associated with the received beacon will be used by other UEs. If so and the BS wants to minimize the risk of collisions, the use of the first set of grant-free resources may not be confirmed. But if not, the use of the first set of grant-free resources may be confirmed.

[0039] Alternatively, in the case that the UE only transmits a pre-emption beacon signal when it does not intend to use the configured first set of grant-free resources, this determination may be based, at least partly, on checking which UEs have not transmitted the pre-emption beacon signal yet. If only one pre-emption beacon signal is not received, the BS can confirm the use of the configured set of grant-free resources to the UE in question directly. Otherwise the BS may need to select one or a subset of the UEs that has not transmitted the pre-emption beacon and confirm the use of the first configured set of grant-free resources accordingly to minimize collisions. In some embodiments, the BS may decode signals received from multiple UEs, even if the signals from multiple UEs would collide.

[0040] Moreover, in some embodiments the BS may also determine that no indication related to the first set of grant-free resources was detected before the first set of grant-free resources. For example, if the pre-emption beacon signal is used to indicate that the UE intends to transmit data using the first set of grant-free resources configured for the UE but no pre-emption beacon signal was received, the BS may determine that no indication was detected. Alternatively, if the non-detection of the pre-emption, i.e., lack of the pre-emption beacon signal is used to indicate the UE intends to transmit data using the first set of grant- free resources configured for the UE but all pre-emption beacons were received, the BS may determine that no indication to use the resource was detected. Upon determining that no indication was detected, the BS may allocate a grant-based resource for another terminal, wherein the grant-based resource at least partly overlaps with the first set of grant- free resources.

[0041] In response to the pre-emption beacon signal, or alternatively to the non- detection of it, the BS may transmit a confirmation message to the UE, for which the first set of grant-free resources has been configured, to indicate that it can use the configured first set of grant-free resources. The confirmation message may be referred to as a second message. The second message, i.e., the confirmation message, may be a confirmation message for confirming, or permitting, the use of the configured first set of grant-free resources. Alternatively, the BS may indicate to the UE that it cannot use the configured set of grant-free resources by not transmitting the confirmation message. The confirmation message may be thus referred to as an indication of the BS about whether the use of the first set of grant-free resources configured for the UE is confirmed. Hence the UE may determine, based on the confirmation message, whether the use of the first set of grant-free resources configured for the UE is confirmed. That is to say, if confirmation is received, the use is confirmed. If the confirmation message is not received, the use is not confirmed, or permitted.

[0042] Alternatively, in some embodiments of the present invention, the BS may indicate that the use of the configured set of grant-free resources is confirmed by not transmitting the confirmation message. Thus, in that case the UE may detect lack of the confirmation message and determine, based on non-detecting of the confirmation message, that it can use the configured set of grant-free resources. On the other hand, the BS may indicate to the UE that it cannot use the configured set of grant-free resources by transmitting the confirmation message. Lack of the confirmation message, i.e., non- detection, may be therefore referred to as an indication whether the use of the first set of grant-free resources configured for the UE is confirmed as well.

[0043] Consequently, the BS may receive, depending on whether the use of the first set of grant-free resources configured for the terminal is confirmed, the data from the first terminal. If the use of the first set of grant-free resources was confirmed, the BS may receive the data using the first set of grant-free resources.

[0044] However, if the use of the first set of grant-free resources was not confirmed, or permitted, the BS may receive a subsequent indication that the UE intends to transmit the data using a subsequent set of grant-free resources configured for the UE. In response, the BS may confirm the use of the subsequent set of grant-free resources and receive the data using the subsequent set of grant-free resources. Alternatively, if the use of the first set of grant-free resources was not confirmed, the BS may allocate a grant-based resource for the UE and receive the data using the grant-based resource.

[0045] In general, confirmation message may be transmitted before all configured sets of grant-free resources, or resource groups. The confirmation message may be specifically addressed to the UE in question. Alternatively, or in addition, the pre-emption beacon signal, i.e., first message, may comprise an identity of the UE. The identity of the UE may be implicitly signalled, for example, using a UE-specific signal.

[0046] In some embodiments, the confirmation message may indicate to the UE that it should use another configured set of grant-free resources for the transmission, if the use of the first set of grant-free resources configured for the first terminal is not confirmed. So the UE may be configured with more than one set of grant-free resources, or resource groups, as well. Thus, if the UE is configured for multiple set of grant-free resources, or groups of grant-free resources, it may need to listen to confirmation signals for all of the configured sets of grant-free resources, or groups. The confirmation signal may indicate that the UE needs to switch from one configured set of grant-free resources, or resource group, to another. Therefore, the UE may need to switch between the multiple sets of grant- free resources, or groups, if this is indicated in the confirmation signal.

[0047] If a UE has previously indicated its intention to transmit on the configured set of grant-free resources, e.g., by transmitting the pre-emption beacon signal, it may only transmit using the configured set of grant-free resources if it receives the confirmation message from the BS. Alternatively, in some embodiments the UE may only transmit using the configured set of grant-free resources if it does not detect/receive the confirmation message from the BS.

[0048] According to some embodiments of the present invention, the pre-emption beacon signal may also be used by other UEs, if it can be received and decoded by other UEs, to detect and potentially avoid or reduce collisions between grant-based and grant- free transmission, or between grant-free transmissions

[0049] The time between the transmission of the pre-emption beacon signal and the start of the data transmission using a set of grant-free resources may be referred to as a pre-emption time. The pre-emption time may be fixed and it may be, for example, defined by standard specifications. In some embodiments of the present invention, the pre-emption time may be defined so that it equals or exceeds the time it takes to handle the message exchange, including transmission and reception of the pre-emption beacon signal and the confirmation message.

[0050] As an example, preparation and transmission of the pre-emption beacon signal may take 2 symbols, at minimum, at the UE. In addition, reception and decoding, may take 2 symbols at the BS, preparation and transmission of the confirmation message may take 2 symbols and 2 symbols may be reserved for other actions taken by the BS. Thus, the pre-emption time should be at least 8 symbols according to this example.

[0051] However, if the pre-emption signal is transmitted only when the set of grant- free resources is not used by the UE, the action by the BS does not need to be signaled to the UE. Thus, it is not necessary to reserve time for preparation and transmission of the confirmation message and consequently the pre-emption time may be 6 symbols in this latter case.

[0052] Minimum processing time for a grant-free transmission may be, e.g., 3 symbols according to some 3GPP agreements, such as, for Ultra Reliable Low Latency Communications, URLLC. The UE therefore can process/prepare the grant-free transmission during the pre-emption time. [0053] However, another issue may arise related to the timing. In view of the above example, if data arrives at the buffer of the UE less than 8 (or 6 in the latter case) but more than 3 symbols before the start of a configured set of grant-free resources, the UE would have time for processing/preparing the data transmission for transmission on the configured set of grant-free resources. However, there would not be enough time for transmitting the pre-emption beacon and receiving the confirmation message. In some embodiments of the present invention such an issue may be solved by considering two possible, configurable actions for the UE, which may depend on a type of a service associated with the data to be transmitted.

[0054] So for example, the UE may determine that the service associated with the data to be transmitted using the set of grant-free resources is non-delay tolerant, i.e., delay intolerant. Such a non-delay tolerant service may be, for example, URLLC service. The determination may be based on network configuration as well. That is to say, the BS may configure the use of the set of grant-free resources based on the service. Upon determining the service associated with the data as delay intolerant, the UE may decide not to transmit the pre-emption beacon. That is to say, it may not be possible to use the pre-emption beacon for very low latency and delay intolerant services.

[0055] Alternatively, the UE may determine that the service associated with the data to be transmitted using the set of grant-free resources is delay tolerant. Such a delay tolerant service may be, for example, Ultra/High Reliable and Latency Tolerant service. Upon determining the service associated with the data as delay tolerant, the UE may decide to skip the configured set of grant-free resources and use the subsequent one for the data transmission. For the subsequent set of grant-free resources configured for the UE a pre- emption beacon signal may be transmitted by taking into account the pre-emption time, as usual. So the pre-emption beacon signal may be transmitted e.g., 6 symbols before the start of the subsequent grant-free transmission.

[0056] In some embodiments, an uplink/downlink grant for grant-based transmission on a configured set of grant-free resources may be transmitted only upon detecting that there were no uplink pre-emption beacon signals for the grant-free resources.

[0057] Moreover, in some embodiments, if the BS detects multiple pre-emption beacon signals for a set of grant-free resources which has been configured for several UEs, the BS may reconfigure its receiver algorithm so that it can decode multiple, overlapping grant-free transmissions better. The reconfiguration may be based, at least partly, on measured power levels of the received pre-emption beacon signals. [0058] FIGURE 2 illustrates a first example in accordance with at least some embodiments of the present invention. In FIGURE 2, time, t, is presented on the x-axis while frequency, f, is presented on the y-axis. Resource blocks are shown as black boxes. Moreover, time instant, t1, may refer to a time when data arrives to a buffer of a first UE. Upon arrival of the data to be transmitted, the first UE may decide to transmit data using a configured uplink set of grant-free resources and start preparing a baseband signal, i.e., a transport block, for the data transmission.

[0059] Prior to the transmission of the transport block using the configured set of grant-free resources, the first UE may transmit a pre-emption beacon signal, or a first message in general, to the BS at time t2. The pre-emption signal may comprise one or more resource blocks 210. Also, the pre-emption beacon signal may indicate that the first UE intends to transmit the data using the next set of grant-free resources 240 configured for the first UE. Sometimes, a second UE may also have a need to transmit data using the next set of grant-free resources 240 and hence, it may transmit its own pre-emption beacon signal to the BS relatively close to time instant t2. The pre-emption beacon signals may comprise identities of the UEs.

[0060] Upon receiving the pre-emption signal 210 of the first UE, and possibly the pre-emption signal of the second UE, the BS may respond by transmitting a confirmation message, or a second message in general, to the first UE at time instant t3. The confirmation message may comprise one or more resource blocks 230 and it may be specifically addressed to the first UE. However, the BS may decide not to transmit a confirmation message to the second UE. The second UE may, or may not, receive the confirmation message directed to the first UE but as the confirmation message is addressed to the first UE, the second UE would know that it is not a confirmation message addressed for it.

[0061] Time between the transmission of the pre-emption beacon signal 210 and reception of the confirmation message 230 is denoted by 220. During time period 220 the first UE may prepare the data transmission. Time period 220 may be referred to as the pre- emption time and it may have fixed time duration, e.g., certain number of symbols in time.

[0062] After transmission of the pre-emption beacon signal, the first UE may listen for a confirmation message from the BS at a specific time instant. For example, the first UE may listen just before the start of the configured set of grant-free resources. In some embodiments, the first UE may initiate data transmission using the configured set of grant- free resources only if it receives a confirmation message. Alternatively, in some other embodiments, the UE may initiate data transmission using the configured set of grant-free resources only if it does not receive a confirmation message. [0063] In the embodiment of FIGURE 2, the confirmation message may inform the first UE that it may use the set of grant-free resources for transmission of the data. Thus, the first UE may start transmission of the data at time instant t4, which denotes the start of the configured set of grant-free resources in time. However, as the second UE did not receive any confirmation message addressed to it, the second UE may not transmit its data using the set of grant-free resources 240, even though the resource was configured for the second UE as well. Collisions are therefore avoided while enabling allocation of a set of grant-free resources to multiple users.

[0064] In some embodiments of the present invention, the first UE may be configured for multiple sets of grant-free resources. If so, the first UE may initiate the data transmission using a second set of grant-free resources based on the indication in the confirmation message.

[0065] As time elapses between the end of the pre-emption beacon signal and the start of the uplink transmission using the set of grant-free resources, the pre-emption beacon signal may overlap in time with other grant-free or grant-based resources. This may require mechanisms to puncture/rate match the overlapping transmissions. For example, a change of a transmission parameter may be signaled in the corresponding uplink/downlink grants. The change may apply to both, grant-based transmissions and configured grant- free uplink transmissions.

[0066] As an alternative, the pre-emption beacon signal may be allowed to overlap with other transmissions. In this case, a specific design requirement may be that the pre- emption beacon signal needs to occupy a limited amount of frequency/time resources, and should be particularly resilient to interference.

[0067] In some embodiments, the confirmation message may indicate to the UE that it can initiate data transmission using the configured set of grant-free resources. Moreover, in some embodiments the confirmation message may indicate to the UE that it cannot initiate data transmission using the configured set of grant-free resources. In addition, in some embodiments the confirmation message may indicate to the UE that it may initiate transmission using another set of grant-free resources configured for the UE.

[0068] As shown in FIGURE 2, transmission of the pre-emption beacon signal 210 is followed by a confirmation signal 230 for uplink grant-free transmissions. The UE may send a pre-emption beacon signal in advance compared to the actual grant-free transmission, and wait for an indication from the BS prior to transmission of data using the set of grant- free resources. [0069] FIGURE 3 illustrates a second example in accordance with at least some embodiments of the present invention. FIGURE 3 demonstrates how embodiments of the present invention may be used to allow grant-based transmissions on grant-free resources.

[0070] Also in FIGURE 3, time, t, is presented on the x-axis while frequency, f, is presented on the y-axis. Moreover, time instant, t1, may refer to a time when data, which needs to be transmitted, arrives to a buffer of a second UE. The second UE may not have a configured set of grant-free resources for transmission of data. Thus, the second UE may send a request for a grant-based resource upon arrival of the data. Typically, sending of the request by the second UE and a corresponding grant may take place much before time instant t2, which indicates a time the first UE would send a pre-emption beacon signal, if the first UE would have data to send using the configured set of grant-free resources.

[0071] In this embodiment the first UE may not have data to transmit using the configured set of grant-free resources and hence the first UE does not transmit a pre- emption beacon signal to the BS at time t2. Consequently, the BS does not transmit a confirmation message to the first UE at time t3 either. Instead, the BS may allocate a grant- based resource for the second UE, wherein the grant-based resource may overlap, at least partly, with the set of grant-free resources. As the BS does not transmit the confirmation message, the first UE will not transmit using the configured set of grant-free resources.

[0072] FIGURE 4 illustrates an example apparatus capable of supporting at least some embodiments of the present invention. Illustrated is device 400, which may comprise, for example, UE 1 10, 120 or 130, a terminal or mobile station, or BS 140, such as, a network node of FIGURE 1 . Comprised in device 400 is processor 410, which may comprise, for example, a single- or multi-core processor wherein a single-core processor comprises one processing core and a multi-core processor comprises more than one processing core. Processor 410 may comprise, in general, a control device. Processor 410 may comprise more than one processor. Processor 410 may be a control device. A processing core may comprise, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core produced by Advanced Micro Devices Corporation. Processor 410 may comprise at least one Qualcomm Snapdragon and/or Intel Atom processor. Processor 410 may comprise at least one application-specific integrated circuit, ASIC. Processor 410 may comprise at least one field-programmable gate array, FPGA. Processor 410 may be means for performing method steps in device 400. Processor 410 may be configured, at least in part by computer instructions, to perform actions.

[0073] A processor may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with embodiments described herein. As used in this application, the term“circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and/or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and/or digital hardware circuit(s) with software/firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0074] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0075] Device 400 may comprise memory 420. Memory 420 may comprise random- access memory and/or permanent memory. Memory 420 may comprise at least one RAM chip. Memory 420 may comprise solid-state, magnetic, optical and/or holographic memory, for example. Memory 420 may be at least in part accessible to processor 410. Memory 420 may be at least in part comprised in processor 410. Memory 420 may be means for storing information. Memory 420 may comprise computer instructions that processor 410 is configured to execute. When computer instructions configured to cause processor 410 to perform certain actions are stored in memory 420, and device 400 overall is configured to run under the direction of processor 410 using computer instructions from memory 420, processor 410 and/or its at least one processing core may be considered to be configured to perform said certain actions. Memory 420 may be at least in part comprised in processor 410. Memory 420 may be at least in part external to device 400 but accessible to device 400.

[0076] Device 400 may comprise a transmitter 430. Device 400 may comprise a receiver 440. Transmitter 430 and receiver 440 may be configured to transmit and receive, respectively, information in accordance with at least one cellular or non-cellular standard. Transmitter 430 may comprise more than one transmitter. Receiver 440 may comprise more than one receiver. Transmitter 430 and/or receiver 440 may be configured to operate in accordance with Global System for Mobile communication, GSM, Wideband Code Division Multiple Access, WCDMA, 5G, Long Term Evolution, LTE, IS-95, Wireless Local Area Network, WLAN, Ethernet and/or Worldwide Interoperability for Microwave Access, WiMAX, standards, for example.

[0077] Device 400 may comprise a Near-Field Communication, NFC, transceiver 450. NFC transceiver 450 may support at least one NFC technology, such as Bluetooth, Wibree or similar technologies.

[0078] Device 400 may comprise User Interface, Ul, 460. Ul 460 may comprise at least one of a display, a keyboard, a touchscreen, a vibrator arranged to signal to a user by causing device 400 to vibrate, a speaker and a microphone. A user may be able to operate device 400 via Ul 460, for example to accept incoming telephone calls, to originate telephone calls or video calls, to browse the Internet, to manage digital files stored in memory 420 or on a cloud accessible via transmitter 430 and receiver 440, or via NFC transceiver 450, and/or to play games.

[0079] Device 400 may comprise or be arranged to accept a user identity module 470. User identity module 470 may comprise, for example, a Subscriber Identity Module, SIM, card installable in device 400. A user identity module 470 may comprise information identifying a subscription of a user of device 400. A user identity module 470 may comprise cryptographic information usable to verify the identity of a user of device 400 and/or to facilitate encryption of communicated information and billing of the user of device 400 for communication effected via device 400.

[0080] Processor 410 may be furnished with a transmitter arranged to output information from processor 410, via electrical leads internal to device 400, to other devices comprised in device 400. Such a transmitter may comprise a serial bus transmitter arranged to, for example, output information via at least one electrical lead to memory 420 for storage therein. Alternatively to a serial bus, the transmitter may comprise a parallel bus transmitter. Likewise processor 410 may comprise a receiver arranged to receive information in processor 410, via electrical leads internal to device 400, from other devices comprised in device 400. Such a receiver may comprise a serial bus receiver arranged to, for example, receive information via at least one electrical lead from receiver 440 for processing in processor 410. Alternatively to a serial bus, the receiver may comprise a parallel bus receiver.

[0081] Device 400 may comprise further devices not illustrated in FIGURE 4. For example, where device 400 comprises a smartphone, it may comprise at least one digital camera. Some devices 400 may comprise a back-facing camera and a front-facing camera, wherein the back-facing camera may be intended for digital photography and the front- facing camera for video telephony. Device 400 may comprise a fingerprint sensor arranged to authenticate, at least in part, a user of device 400. In some embodiments, device 400 lacks at least one device described above. For example, some devices 400 may lack a NFC transceiver 450 and/or user identity module 470.

[0082] Processor 410, memory 420, transmitter 430, receiver 440, NFC transceiver 450, Ul 460 and/or user identity module 470 may be interconnected by electrical leads internal to device 400 in a multitude of different ways. For example, each of the aforementioned devices may be separately connected to a master bus internal to device 400, to allow for the devices to exchange information. However, as the skilled person will appreciate, this is only one example and depending on the embodiment various ways of interconnecting at least two of the aforementioned devices may be selected without departing from the scope of the present invention.

[0083] FIGURE 5 is a flow graph of a first method in accordance with at least some embodiments of the present invention. The phases of the illustrated first method may be performed by UE 1 10, 120 or 130 or a first terminal in general, or by a control device configured to control the functioning thereof, possibly when installed therein.

[0084] The first method may comprise, at step 510, indicating to a network node that a first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal. The first method may also comprise, at step 520, determining, based on an indication of the network node, whether the use of the first set of grant-free resources configured for the first terminal is confirmed. In addition, the first method may comprise, at step 530, transmitting, depending on determining whether the use of the first set of grant- free resources configured for the first terminal is confirmed, the data to the network node.

[0085] FIGURE 6 is a flow graph of a second method in accordance with at least some embodiments of the present invention. The phases of the illustrated second method may be performed by BS 140 or a network node in general, or by a control device configured to control the functioning thereof, possibly when installed therein.

[0086] The second method may comprise, at step 610, determining, based on an indication of a first terminal, that the first terminal intends to transmit data using a first set of grant-free resources configured for the first terminal. The second method may also comprise, at step 620, indicating to the first terminal whether the use of the first set of grant- free resources configured for the first terminal is confirmed. In addition, the second method may comprise, at step 630, receiving, depending on whether the use of the first set of grant- free resources configured for the first terminal is confirmed, the data from the first terminal. [0087] In some embodiments, the first and the second method may comprise transmission and reception of a pre-emption beacon, which may be referred to as a first message. Similarly, the first and the second method may comprise transmission and reception of a confirmation message, which may be referred to as a second message.

[0088] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0089] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or“in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Where reference is made to a numerical value using a term such as, for example, about or substantially, the exact numerical value is also disclosed.

[0090] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0091] In an exemplary embodiment, an apparatus, such as, for example, a terminal or a network node, may comprise means for carrying out the embodiments described above and any combination thereof.

[0092] In an exemplary embodiment, a computer program may be configured to cause a method in accordance with the embodiments described above and any combination thereof. In an exemplary embodiment, a computer program product, embodied on a non- transitory computer readable medium, may be configured to control a processor to perform a process comprising the embodiments described above and any combination thereof. [0093] In an exemplary embodiment, an apparatus, such as, for example, a terminal or a network node, may comprise at least one processor, and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform the embodiments described above and any combination thereof.

[0094] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0095] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0096] The verbs“to comprise” and“to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or“an”, that is, a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0097] At least some embodiments of the present invention find industrial application in communication networks, wherein grant-free resources are used.

ACRONYMS LIST

AUL Autonomous Uplink

DMRS Demodulation Reference Signal eMBB enhanced Mobile BroadBand

GSM Global System for Mobile communication,

GUL Grant-less Uplink

loT Internet of Things

LAA Lincense Assisted Access

LTE Long-Term Evolution

NFC Near-Field Communication

NR New Radio

RAT Radio Access Technology

SIM Subscriber Identity Module

SPS Semi-Persistent Scheduling

UE User Equipment

Ul User Interface

URLLC Ultra Reliable Low Latency Communications

VoIP Voice over IP

WCDMA Wideband Code Division Multiple Access

WiMAX Worldwide Interoperability for Microwave Access

WLAN Wireless Local Area Network

REFERENCE SIGNS LIST