CN111919481B

CN111919481B - Method, apparatus, and computer readable medium for uplink transmission in wireless communication system

Info

Publication number: CN111919481B
Application number: CN201880091981.1A
Authority: CN
Inventors: 骆喆; 陶涛; 刘建国; 孟艳; 王钧; 沈钢
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2018-03-29
Filing date: 2018-03-29
Publication date: 2023-03-24
Anticipated expiration: 2038-03-29
Also published as: WO2019183889A1; CN111919481A

Abstract

Embodiments of the present disclosure relate to methods, devices, and computer-readable media for communication. A network device includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code configured to, with the at least one processor, cause the network device at least to: transmitting a scheduling message to the terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; detecting a transmission in the reserved first time interval; and in response to failing to successfully detect a transmission in the first time interval, detecting a transmission in a second time interval not reserved for transmissions.

Description

Method, apparatus, and computer readable medium for uplink transmission in wireless communication system

Technical Field

The non-limiting and example embodiments of the present disclosure relate generally to the field of wireless communication technology, and in particular, relate to a method, apparatus, and computer-readable medium for uplink transmission in a wireless communication system.

Background

This section introduces aspects that may help to better understand the disclosure. Accordingly, the statements in this section should be read in this light and not as admissions of what is present in the prior art or what is not present in the prior art.

Currently, new fifth generation (5G) wireless communication technologies are being investigated in the third generation partnership project (3 GPP). An access technology called New Radio (NR) will be employed in 5G communication systems.

In 3GPP, a new research project named "Study on NR-based Access to unlicenced Spectrum" was agreed 3.2017, and details of the protocol can be found in final report v1.0.0 of 3GPP Technical Specification Group (TSG) Random Access Network (RAN) working group 1 (WG 1) #88 conference held in yas greece, 3.2.13 to 17.2017. The present research project studies techniques that may allow operators to enhance their service offerings by utilizing unlicensed spectrum. A detailed description of this research project can be found in 3GPP document RP-170828.

Unlicensed spectrum may be used in either Licensed Assisted Access (LAA) mode or standalone mode, which will be employed in future versions of the MulteFire (MF) technology (e.g., version 2.0).

In addition, it is assumed that NR technology supports various types of services including, for example, enhanced mobile broadband (eMBB), large-scale machine type communication (mtc), and ultra-reliable low latency communication (URLLC). These services require different quality of service (QoS) in terms of delay, data rate and/or packet loss rate. For example, URLLC services require low latency and/or high reliability.

Disclosure of Invention

Various embodiments of the present disclosure are generally directed to improving communications in a wireless communication network.

In a first aspect of the disclosure, a network device is provided. The network device includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code configured to, with the at least one processor, cause the network device at least to: transmitting a scheduling message to the terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; detecting a transmission in the reserved first time interval; and in response to failing to successfully detect a transmission in the first time interval, detecting a transmission in a second time interval not reserved for transmissions.

In a second aspect of the disclosure, a terminal device is provided. The terminal device includes at least one processor and at least one memory including computer program code. The at least one memory and the computer program code configured to, with the at least one processor, cause the terminal device at least to: receiving a scheduling message from the network device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; determining an availability of a first time interval for transmission; determining availability of a second time interval not reserved for transmission in response to the first time interval not being available; and if the second time interval is available, performing the transmission in the second time interval not reserved for the transmission.

In a third aspect of the disclosure, a network device is provided. The network device includes: means for transmitting a scheduling message to the terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; means for detecting a transmission in the reserved first time interval; and means for detecting a transmission in a second time interval not reserved for transmission in response to failing to successfully detect a transmission in the first time interval.

In a fourth aspect of the present disclosure, a terminal device is provided. The terminal device comprises means for receiving a scheduling message from the network device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; means for determining availability of a first time interval for transmission; means for determining availability of a second time interval not reserved for transmission in response to determining that the first time interval is not available; and means for performing a transmission in the second time interval in response to determining that the second time interval is available.

In a fifth aspect of the disclosure, a method performed by a network device is provided. The method comprises the following steps: transmitting a scheduling message to the terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device; detecting a transmission in the reserved first time interval; and in response to failing to successfully detect a transmission in the first time interval, detecting a transmission in a second time interval not reserved for transmissions.

In a sixth aspect of the disclosure, a method performed by a terminal device is provided. The method comprises the following steps: receiving a scheduling message from a network device, the scheduling message indicating a first time interval reserved for transmissions from a terminal device; determining an availability of a first time interval for transmission; determining availability of a second time interval not reserved for transmission if the first time interval is not available; and if the second time interval is available, performing a transmission in the second time interval.

In a seventh aspect of the present disclosure, there is provided a computer readable medium having stored thereon a computer program which, when executed by an apparatus, causes the apparatus to perform the method of the fifth aspect of the present disclosure.

In an eighth aspect of the present disclosure, there is provided a computer readable medium having a computer program stored thereon, which when executed by an apparatus, causes the apparatus to perform the method of the sixth aspect of the present disclosure.

Drawings

The above and other aspects, features and benefits of various embodiments of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings in which like reference numerals are used to refer to like or equivalent elements. The accompanying drawings, which are included to provide a further understanding of embodiments of the disclosure and are not necessarily drawn to scale, wherein:

FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

fig. 2 shows an example of message 3 (Msg 3) transmission during an initial access procedure in unlicensed spectrum;

FIG. 3 illustrates an example of multislot scheduling;

fig. 4 shows a flow chart of a method for communication in a network device according to an embodiment of the present disclosure;

fig. 5 illustrates an example of scheduling and transmission in accordance with some embodiments of the present disclosure;

fig. 6 shows a flow chart of another method in a terminal device according to an embodiment of the present disclosure; and

fig. 7 shows a simplified block diagram of an apparatus that may be implemented as or included in a terminal device or a network device according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. It is to be understood that all such embodiments are presented solely to enable those skilled in the art to better understand and further practice the present disclosure, and are not intended to limit the scope of the present disclosure. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.

References in the specification to "one embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be termed a second element, and, similarly, a second element may be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and/or" includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used herein, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof.

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 analog and/or digital circuitry only); and

(b) A combination of hardware circuitry and software, such as (where applicable):

(i) Combinations of analog and/or digital hardware circuit(s) and software/firmware, and

(ii) Any portion of hardware processor(s) with software (including digital signal processor(s), software, and memory(s) that work together to cause a device such as a mobile phone or server to perform various functions); and

(c) Hardware circuit(s) and/or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), require software (e.g., firmware) for operation, but this software may not be present when it is not required for operation.

This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term "circuitry" also encompasses implementations that are part of only a hardware circuit or processor (or multiple processors) or a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also encompasses (e.g., 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 a server, a cellular network device, or other computing or network device.

As used herein, the term "wireless communication network" refers to a network that conforms to any suitable wireless communication standard, such as New Radio (NR), long Term Evolution (LTE), LTE-advanced (LTE-a), wideband Code Division Multiple Access (WCDMA), high Speed Packet Access (HSPA), and the like. The "wireless communication network" may also be referred to as a "wireless communication system". Further, communication between network devices, between a network device and a terminal device, or between terminal devices in a wireless communication network may be performed according to any suitable communication protocol, including but not limited to global system for mobile communications (GSM), universal Mobile Telecommunications System (UMTS), LTE-a, NR, wireless Local Area Network (WLAN) standards, such as the IEEE 802.11 standards, and/or any other suitable wireless communication standard currently known or to be developed in the future.

As used herein, the term "network device" refers to a device in a wireless communication network via which a terminal device accesses the network and receives services therefrom. A network device may refer to a Base Station (BS) or an Access Point (AP), e.g., a NodeB (NodeB or NB), evolved NodeB (eNodeB or eNB), next generation NodeB (gNB), remote Radio Unit (RRU), radio Head (RH), remote Radio Head (RRH), relay, low power node (such as femto NB, pico NB, etc.), depending on the terminology and technology applied.

The term "terminal device" refers to any terminal device capable of accessing a wireless communication network and receiving services therefrom. By way of example, and not limitation, a terminal device may be referred to as a User Equipment (UE), subscriber Station (SS), portable subscriber station, mobile Station (MS), or Access Terminal (AT). The end devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable devices, personal Digital Assistants (PDAs), portable computers, desktop computers, image capture end devices (such as digital cameras), gaming end devices, music storage and playback appliances, wearable end devices, in-vehicle wireless end devices, wireless endpoints, mobile stations, laptop Embedded Equipment (LEEs), laptop Mounted Equipment (LMEs), USB dongle, smart devices, wireless Customer Premises Equipment (CPE), and the like. In the following description, the terms "terminal device", "terminal", "user equipment" and "UE" may be used interchangeably.

As one example, the terminal device may represent a UE configured to communicate in accordance with one or more communication standards promulgated by 3GPP, such as the GSM, UMTS, LTE, 5G, and/or MulteFire standards of 3 GPP. As used herein, a "user equipment" or "UE" may not necessarily have a "user" in terms of a human user owning and/or operating the relevant equipment. In some embodiments, the terminal device may be configured to transmit and/or receive information without direct human interaction. For example, when triggered by an internal or external event, or in response to a request from a wireless communication network, a terminal device may be designed to transmit information to the network on a predetermined schedule. Alternatively, the UE may represent a device intended for sale to or operated by a human user, but which may not be initially associated with a particular human user.

As another example, in an internet of things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements and transmits results of such monitoring and/or measurements to another terminal device and/or network device. In this case, the terminal device may be a machine-to-machine (M2M) device, which may be referred to as a Machine Type Communication (MTC) device in the 3GPP context. As one particular example, the terminal device may be a UE implementing the 3GPP narrowband internet of things (NB-IoT) standard. Specific examples of such machines or devices are sensors, metering devices (such as electricity meters), industrial machinery, or household or personal appliances (e.g., refrigerators, televisions, personal wearable devices (such as watches), etc.). In other cases, the terminal device may represent a vehicle or other device capable of monitoring and/or reporting its operational status or other functionality associated with its operation.

Fig. 1 illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. As shown, communication network 100 may include one or more network devices, such as network device 101, which may be in the form of an eNB or a gNB. It should be understood that network device 101 may also be in the form of a node B, BTS (base transceiver station) and/or BSS (base station subsystem), access Point (AP), etc. Network device 101 provides radio connectivity to a set of terminal devices, such as terminal devices 102-1, 102-2, and 102-3, collectively referred to as terminal device(s) 102. Although only three terminal devices are shown in fig. 1 for simplicity, it should be understood that more or fewer terminal devices may in fact be included in the communication network.

The network device 101 serves the terminal device 102 through a licensed or unlicensed band, and services provided by the network device 101 to different terminal devices may be different. For example, the terminal device 102-1 may receive the eMBB service from the network device 101, while the terminal device 102-3 may receive the URLLC service. These services may require different transmission/reception performance in terms of delay, data rate, and/or packet loss rate.

For example, URLLC services require low latency and/or high reliability as an important application to be supported in NR. For example, 10 may be required for uplink/downlink of URLLC traffic ^-5 High reliability probability of transport block error rate, 1ms delay and 0.5ms user plane delay. As used herein, downlink (DL) transmissions refer to transmissions from a network device to a terminal device, and Uplink (UL) transmissions refer to transmissions in the opposite direction.

For a terminal device in Radio Resource Control (RRC) idle or disconnected mode, most of its transmission delay/latency is contributed by the initial access procedure, which is a contention-based random access procedure to be performed by the terminal device for (re) connecting to a network device (e.g., a gNB) prior to normal traffic transmission. In NR and LTE, the initial access procedure includes the following four steps:

step 1: the UE transmits a preamble on a Physical Random Access Channel (PRACH);

step 2: the gNB/eNB transmits a Random Access Response (RAR) message to the UE;

and 3, step 3: the UE transmits a message 3 (Msg 3) based on the UL grant included in the received RAR; and

and 4, step 4: the gNB/eNB transmits a message 4 (Msg 4) to confirm that Msg3 has been received from the UE.

To support delay sensitive applications, the latency of the above steps should be reduced. Furthermore, it is also important to reduce the latency of communications in the unlicensed band, as network devices may need to provide services, such as delay-sensitive applications, to one or more terminal devices within their coverage area over the unlicensed band.

Since the unlicensed spectrum is shared by multiple communication systems/devices, in order to avoid interference between different systems/devices, a Listen Before Talk (LBT) mechanism is introduced into communications in the unlicensed band by provisioning. However, LBT mechanisms result in large delays because transmissions may be blocked by LBT failures, e.g., the channel used for transmission may be occupied by other devices. As a result, the delay of the initial access procedure becomes larger in the unlicensed spectrum compared to the licensed band.

Fig. 2 shows an example of Msg3 transmission during an initial access procedure in unlicensed spectrum. As shown in fig. 2, a RAR from a DL slot 201 of a network device schedules a first Msg3 transmission opportunity in a slot 202 outside of a transmission burst 210. The length of the transmission burst 210 may be limited by regulations for unlicensed bands that require that a device should not transmit continuously using an unlicensed band for a time interval exceeding a predefined maximum transmission time (e.g., 8 ms). In the example shown in fig. 2, due to LBT failure, the first Msg3 transmission is blocked, i.e., the channel of slot 202 is occupied by another device (e.g., a WiFi device). The network device then transmits a Downlink Control Indication (DCI) in DL slot 203 for scheduling a retransmission of Msg3 in slot 204. Such DCI is also referred to herein as "retransmitted DCI". Although the second Msg3 transmission opportunity scheduled at slot 204 is within the transmission burst 220, the second Msg3 transmission is still blocked due to LBT failure. The network device then transmits additional retransmitted DCI in slot 205 to schedule Msg3 again. The Msg3 transmission eventually succeeds at the third time in slot 206. In this example, the latency of the Msg3 transmission extends from 4ms to 18ms compared to the normal Msg3 transmission in the licensed band.

As can be seen from fig. 2, msg3 transmissions in unlicensed spectrum may have large delays because the scheduled Msg3 transmission occasions may be blocked and one or more retransmissions may be required. Therefore, there is a need to enhance Msg3 transmission in unlicensed bands. However, a solution to the above problem has not been proposed so far.

In addition, similar latency issues exist in other communication scenarios, such as handover and dual connectivity. For example, during a handover procedure, a terminal device performs non-contention based random access. After receiving the RAR from the network device, the terminal device needs to transmit an RRC signal (e.g., an rrcconnectionreconfiguration complete message) to the network device, and transmission of the RRC signal may be blocked. As another example, in dual connectivity, the terminal device needs to establish an RRC connection with both the primary cell (PCell) and the primary secondary cell (PSCell), and signaling for establishing the RRC connection may be blocked. Therefore, similar problems of large latency as described with reference to fig. 2 also exist in handover and dual connectivity.

To increase UL transmission opportunities, multi-slot scheduling may be used for unlicensed spectrum. For multi-slot scheduling, a single UL grant schedules the transmission of multiple slots, and the transmissions in each slot are independent of each other. In other words, the UL grant for multi-slot scheduling contains scheduling information for multiple legacy UL grants. Multi-slot scheduling may provide many UL transmission opportunities for the UE to overcome LBT failures; however, it cannot be applied directly to Msg3 transmission, since Msg3 only needs to be transmitted once.

As another option for multi-slot scheduling, the network device may schedule multiple slots via UL grants, but the UE transmits in only one of these scheduled slots as a result of UL LBT. An example of this option for multi-slot scheduling is shown in fig. 3. In this example, the network device schedules two Msg3 transmission opportunities for the terminal device at slots n +2 and n +3 via a single grant at slot n, but the terminal device transmits Msg3 using only one of slots n +2 and n + 3. It can be seen that this scheme requires the network device to reserve multiple transmission resources for a single UL transmission at a scheduled time slot to avoid collisions. This results in a large overhead as the over-reserved resources cannot be reused for other purposes and are wasted. Therefore, the number of slots scheduled for Msg3 transmission should be kept small to avoid large overhead.

In this disclosure, methods, apparatuses, and computer-readable media have been proposed to enable efficient UL transmission. Although embodiments of the present disclosure may be used for Msg3 transmissions in unlicensed bands, it should be understood that embodiments of the present disclosure are not limited to such a particular communication scenario, but may be applied to any communication scenario in which similar issues exist. That is, the proposed method, apparatus and computer readable medium may also be used for transmitting other signals in a licensed or unlicensed frequency band.

Fig. 4 illustrates a flow chart of a method 400 in a wireless communication system (e.g., communication system 100 in fig. 1). The method may be implemented by, for example, network device 101 shown in fig. 1. For ease of discussion, the method 400 will be described below with reference to the network device 101 and the communication system 100 shown in fig. 1. However, embodiments of the present disclosure are not limited thereto.

As shown in fig. 4, at block 410, network device 101 transmits a scheduling message to a terminal device (e.g., terminal device 102 in fig. 1). The scheduling message indicates a first time interval reserved for a transmission (such as, but not limited to, a Msg3 transmission) from the terminal device 102.

By way of example and not limitation, the scheduling message may be transmitted via a RAR signal or a Physical Downlink Control Channel (PDCCH) signal, e.g., in a Common Physical Downlink Control Channel (CPDCCH). However, it should be understood that embodiments are not limited to any particular signaling or format for carrying scheduling messages.

In some embodiments, the reserved first time interval may provide a plurality of transmission occasions for transmissions from the terminal device 102. Some examples of scheduling and transmission of Msg3 are shown in fig. 5. In one example, network device 101 transmits a scheduling message to terminal device 102 at DL slot n, and the scheduling message indicates a time interval 510, the time interval 510 including slots n +2, n +3, and n +4 reserved for transmissions from terminal device 102.

Reference is now made back to fig. 4. At block 420, network device 101 detects a transmission in a reserved first time interval (e.g., time interval 510 in fig. 5). In some embodiments, to fill the scheduled first time interval, the terminal device 102 may transmit a plurality of signals using a plurality of transmission occasions included in the first time interval. In these embodiments, at block 420, network device 101 may detect a first signal (e.g., msg3 501 shown in example 1 of fig. 5) from terminal device 102 in a first available transmission opportunity of the plurality of transmission opportunities (e.g., slot n +2 in fig. 5) and detect a different second signal (e.g., sounding Reference Signals (SRS) 502 and/or 503 shown in example 1 of fig. 5) from terminal device 102 in additional transmission opportunities of the plurality of transmission opportunities (e.g., slots n +3 and n + 4).

As illustrated in example 2 of fig. 5, in some embodiments, some of the transmission occasions included in the reserved first time interval may not be available for transmission from the terminal device 102. In this case, at block 420 of fig. 4, network device 101 may detect only one transmission (e.g., message 504 at slot n +3 in fig. 5) during first time interval 510.

In some embodiments, all transmission occasions included in the reserved first time interval may not be available for transmission from the terminal device 102, as illustrated in example 3 of fig. 5. In this case, at block 420 of fig. 4, network device 101 fails to detect a transmission in the first time interval.

Reference is now still made to fig. 4. At block 430, network device 101 determines whether the detection in the first time interval was successful. If the detection is successful, network device 101 may end the detection at block 450; however, the embodiments are not limited thereto. In some embodiments, network device 101 may continue its detection in such a case.

If the detection is determined to be unsuccessful at block 430 (e.g., due to an LBT failure as shown in example 3 of fig. 5), network device 101 continues to detect transmissions in a second time interval (e.g., time interval 520 in fig. 5) not reserved for transmissions from terminal device 102 using the scheduling message at block 440. In example 3 of fig. 5, network device 101 detects Msg3 505 at slot n +5 in unreserved second time interval 520.

In this way, the terminal device 102 is allowed to transmit in the scheduled first time interval and the unscheduled second time interval. This increases the transmission opportunities for the terminal device 102. In addition, since additional unreserved resources are allowed for transmissions from the terminal device 102, there is no need to reserve a large amount of transmission resources via scheduling. As a result, the waste of resources due to the reservation is reduced.

In some embodiments, the second time interval not reserved for transmission may comprise a time interval for contention-based transmission. That is, during the second time interval, the terminal device 102 may acquire the transmission occasion in a contention-based manner, e.g., by performing LBT.

In some embodiments, the scheduling message transmitted by network device 101 at block 410 may also indicate a transmission format (e.g., MCS) for the transmission and/or frequency resources for the transmission. In some further embodiments, the transmission format and/or frequency resources indicated in the scheduling message may be applied for transmission in both the reserved first time interval and the unreserved second time interval. Alternatively, the transmission format and/or frequency resources indicated in the scheduling message may be directly applied for transmissions in the reserved first time interval, while the transmission format and/or frequency resources for transmissions in the unreserved second time interval may be implicitly derived based on the scheduling message. It will be appreciated that in some embodiments the transmission format and/or frequency resources used for transmissions from the terminal device 102 may be predefined, and in this case the indication for the transmission format and/or frequency resources may be omitted from the scheduling message.

By way of example and not limitation, method 400 may be performed by network device 101 in an unlicensed frequency band. In this case, the unavailability of the transmission occasions in the first and second time intervals may be caused by LBT failure in the unlicensed band.

In some embodiments, the method 400 may be used to provide an enhanced transmission scheme for Msg3 over unlicensed spectrum. In this scheme, multiple Msg3 transmission opportunities are assigned by network device 101 via the scheduling message transmitted at block 410. However, not all resources for Msg3 transmission are reserved by the scheduling message. Instead, the concept of a reservation window (i.e. a first time interval) may be introduced and resources for the Msg3 transmission occasion within the reservation window are reserved. In the reservation window, the terminal device 102 transmits Msg3 based on the schedule. In contrast, resources outside the reservation window for the Msg3 transmission occasion are not reserved, and in resources outside the reservation window, the terminal device 102 transmits Msg3 based on UE contention. With this scheme, depending on whether the acquired transmission opportunity is inside or outside the reserved window, terminal device 102 may transmit Msg3 at the first Msg3 transmission opportunity with a successful LBT based on network device scheduling or UE contention.

For some unlicensed bands there may be a specification of the maximum transmission time. For example, a device may not be allowed to transmit continuously in the unlicensed band for more than 8ms. Thus, in some embodiments, method 400 may also include block 405, where network device 101 determines a transmission burst time window (e.g., time window 530 shown in fig. 5) for transmission and reception at the network device. In these embodiments, at block 410 of fig. 4, network device 101 transmits a scheduling message during the determined transmission burst time window 530.

In some embodiments, the first time interval allocated by the scheduling message may be within a transmission burst time window and the unreserved second time interval may be outside the transmission burst time window. As shown in fig. 5, in another embodiment, the first time interval (denoted 510 in fig. 5) provides at least a first transmission opportunity (at time slots n +2 and n + 3) within the transmission burst time window 530 and at least a second transmission opportunity (at time slot n + 4) outside the transmission burst time window 530.

Alternatively or additionally, in an embodiment, the second time interval (denoted 520 in fig. 5) may be between a transmission burst time window 530 and a next transmission burst time window 540, as shown in fig. 5.

In the example shown in fig. 5, at slot n within transmission burst time window 530, network device 101 schedules multiple occasions for Msg3 transmission within reservation window 510 via, for example, a UL grant in a RAR or retransmitted DCI. In some embodiments, the reservation window 510 may be defined as an UL slot within the transmission burst time window 530. Alternatively, the network device 101 may inform the terminal device 102 of the UL duration and the offset for determining the reservation window 510 via CPDCCH signaling or RAR.

For scheduled Msg3 opportunities within reservation window 510, network device 101 reserves allocated resources to avoid collisions. In some embodiments, to reuse the over-reserved resources, terminal device 102 may transmit reference signals (e.g., SRS) for training the plurality of transmission beams of the terminal device using the reserved resources (with successful LBT) after the Msg3 transmission within reservation window 510, as shown in example 1 of fig. 5.

Outside of the reservation window 510, the terminal device 102 may acquire the Msg3 opportunity based on UE contention rather than scheduling by the network device 101. In some embodiments, the terminal device 102 may treat all slots outside the reservation window 510 as potential Msg3 opportunities until the start of the next transmission burst 540. If all transmission occasions in the reservation window 510 are not available and the terminal device cannot transmit Msg3 within the reservation window 510, the terminal device 102 transmits Msg3 outside the reservation window (i.e., in the second time interval 520) at the first time instant with a successful LBT, as shown in example 3 of fig. 5. Transmissions outside the reservation window may be performed by reusing some scheduling information (e.g., modulation and Coding Scheme (MCS) and/or frequency domain resource assignment) indicated in the UL grant transmitted by the network device 101 at the RAR or retransmitted DCI at block 410, regardless of the slot configuration. Note that if Msg3 has not been received until the beginning of the next transmission burst 540, network device 101 may transmit the retransmitted DCI in the next transmission burst 540.

It should be understood that embodiments are not limited to any particular signaling format for scheduling messages or scheduling information included in the UL grant from network device 101. For purposes of illustration only and not limitation, the scheduling information may include the information fields shown in table 1.

Table 1 scheduling information in ul grant

In the example shown in fig. 5, network device 101 transmits a RAR to terminal device 102, and the UL grant in the RAR schedules Msg3 transmissions in three slots within reserved window 510. That is, the length of the reservation window 510 is three slots, two of which are within the transmission burst time window 530 and one of which is outside of the transmission burst time window. In some embodiments, the length of the reserved window 510 may be signaled in the CPDCCH.

Alternatively or additionally, the reservation window and frequency resources for Msg3 transmission may be indicated via the scheduling information shown in table 1. The "frequency domain resource assignment" information field allocates frequency domain resources (e.g., physical Resource Blocks (PRBs)) for the Msg3 transmission and may apply to all Msg3 transmission occasions, the "starting slot offset" information field indicates the first slot in which Msg3 may be transmitted, in the embodiment shown in fig. 5 the RAR carrying the UL grant is transmitted in slot n, and if the "starting slot offset" indicates 2 slots, the first slot in which Msg3 may be transmitted is slot n +2, the "duration" information field indicates the length of multiple scheduled Msg3 occasions, i.e., the length of the reservation window 510, in this embodiment the duration is 3 slots, i.e., slots n +2, n +3, and n +4 are scheduled as Msg3 transmission occasions. The frequency resources (e.g., allocated PRBs) indicated by the "frequency domain resource assignment" of the three scheduled slots are reserved for Msg3 transmission with respect to multiplexing. The "time domain resource assignment" information field allocates a symbol (e.g., an Orthogonal Frequency Division Multiplexing (OFDM) symbol in a slot) for the Msg3 transmission opportunity. For example, in this embodiment, the Msg3 transmission occasion may occupy one slot (which may correspond to 14 OFDM symbols), and then the three scheduled slots contain three Msg3 occasions. In another embodiment, the Msg3 transmission occasions may occupy half of the slots (which may correspond to 7 OFDM symbols), and in this case, three scheduled slots provide six Msg3 transmission occasions. Note that the "duration" information field may indicate the length of the reservation window by indicating the number of slots used for the reservation window or the number of transmission occasions included in the reservation window.

As can be seen from the various embodiments described above, the proposed scheme provides more opportunities for transmitting signals (e.g., without limitation, msg 3) by utilizing resources outside of the reservation window based on UE contention rather than network scheduling. In some embodiments, the proposed scheme may significantly reduce the number of retransmissions caused by LBT failures and/or reduce the latency of UL transmissions (e.g., initial access over unlicensed spectrum).

Referring now to fig. 6, fig. 6 illustrates a flow diagram of a method 600 for UL transmission in a wireless communication network. The method may be implemented by, for example, terminal device 102 shown in fig. 1. For ease of discussion, the method 600 will be described below with reference to the terminal device 102 and the communication network 100 shown in fig. 1. However, embodiments of the present disclosure are not limited thereto.

As shown in fig. 6, at block 610, terminal device 102 receives a scheduling message from a network device (e.g., network device 101 shown in fig. 1). The scheduling message indicates a first time interval reserved for transmissions from the terminal device. In some embodiments, the scheduling message received by terminal device 102 at block 610 may be the same as the scheduling message transmitted by network device 101 at block 410 of fig. 4. Accordingly, the description for the scheduling message provided with respect to method 400, table 1, and fig. 5 with respect to fig. 4 also applies here, and details are not repeated.

At block 620, the terminal device 102 determines an availability of a first time interval for transmission. An example of the first time interval may be a reservation window 510 including slots n +2, n +3, and n +4 in fig. 5. As shown in fig. 5, the first time interval may provide a plurality of transmission opportunities for transmission from the terminal device. In the example shown in fig. 5, the first time interval provides 3 transmission opportunities if each transmission opportunity occupies one slot, and 6 transmission opportunities if each transmission opportunity occupies only half a slot.

In some embodiments, the terminal device 102 determines the availability of the first time interval via LBT. For example, a Clear Channel Assessment (CCA) technique or a channel sensing technique may be used for this determination. The first time interval is determined to be unavailable if no transmission occasion is detected as available in the first time interval.

At block 630, if the first time interval (e.g., reservation window 510 in fig. 5) is determined to be unavailable, terminal device 102 determines that a second time interval (e.g., time interval 520 shown in fig. 5) reserved for transmission is not the unavailability reserved for transmission. In some embodiments, the second time interval may comprise a time interval for contention-based transmission.

At block 640, the terminal device 102 performs a transmission in the second time interval if the second time interval is determined to be available. As shown in fig. 5, in some embodiments, the second time interval 520 may include a plurality of transmission occasions and, at block 640, the terminal device 102 may transmit using the first available transmission occasion. In some embodiments, at block 640, end device 102 may transmit Msg3 to network device 101; however, the embodiments are not limited thereto.

In example 3 shown in fig. 5, if LBT performed by terminal device 102 at Msg3 transmission fails within reservation window 510, terminal device 102 continues to perform LBT outside of reservation window 510. The terminal device 102 is allowed to transmit Msg3 using one of the transmission opportunities outside the reserved window 510 before the next transmission burst 540 starts based on the UE contention. In this example, if the terminal device 102 successfully completes its LBT at time slot n +5, it may transmit Msg3 505 at that time slot on the frequency resources indicated or predefined by the scheduling message. In some embodiments, the frequency resources may be indicated in the UL grant using a "frequency domain resource assignment" information field as shown in table 1. In some embodiments, some scheduling information (e.g., MCS) in the UL grant for transmission in the reserved first time interval (e.g., the reservation window 510) may be reused for Msg3 transmission in the unreserved second time interval 520 outside the reservation window 510.

It should be understood that method 600 may or may not be performed in an unlicensed frequency band. In some embodiments, the transmission at block 640 may be performed in an unlicensed frequency band, but the scheduling message may be received in a licensed frequency band at block 610. Alternatively, in some embodiments, both the reception and transmission of the scheduling message are performed in the unlicensed frequency band.

In some embodiments, to avoid potential collisions between the Msg3 transmission from terminal device 102 and the DL transmission from network device 101, terminal device 102 may begin its Msg3 transmission later in a transmission opportunity outside of reserved window 510 (e.g., by deferring the Msg3 transmission by one or more OFDM symbols). That is, terminal device 102 may defer its transmission by a predefined time offset (e.g., 1 OFDM symbol) in an available transmission opportunity in the second time interval before performing the transmission in the available transmission opportunity.

If reserved resources are not available, the method 600 allows the terminal device 102 to transmit using unreserved/unallocated resources. In this way, the transmission opportunities of the terminal apparatus 102 are increased without increasing the resource reservation, and the transmission delay can be reduced.

In some embodiments, in response to determining that the first time interval is available at block 620, the terminal device 102 performs a transmission in the first time interval at block 625. Note that in some embodiments, the first time interval may comprise a plurality of transmission occasions and the terminal device 102 is allowed to transmit in the first time interval at any of the plurality of scheduled transmission occasions as long as the terminal device 102 successfully performed LBT for that transmission occasion. Note that in some embodiments, each transmission opportunity occupies one slot; however, the embodiments are not limited thereto. For example, in another embodiment, a transmission opportunity may occupy half a slot or more than one slot.

To reuse the over-reserved resources, in some embodiments, the terminal device 102 may transmit more than one signal in the first time interval by using more than one transmission opportunity. For example, as shown in example 1 of fig. 5, terminal device 102 may transmit a first signal (e.g., msg3 501) using a first available transmission opportunity (e.g., slot n +2 with a successful LBT in fig. 5) and transmit a different second signal (e.g., SRS 502 and/or 503) using another transmission opportunity (e.g., slot n +3 and/or n +4 in fig. 5). In some embodiments, terminal device 102 may transmit SRS for multiple transmission beams at resources of the second and third available Msg3 transmission occasions. It should be understood that embodiments are not limited to any particular configuration of SRS. As an example, the configuration of the SRS may be predefined (e.g., in a technical specification) or may be notified via the RAR.

In some embodiments, terminal device 102 may fail to transmit Msg3 at the first Msg3 transmission opportunity in reservation window 510 shown in fig. 5 due to LBT failure, and then it transmits Msg3 at the second Msg3 transmission opportunity with a successful LBT. In some embodiments, no SRS is transmitted after the Msg3 transmission because the LBT performed by terminal device 102 at the third Msg3 transmission opportunity (e.g., slot n +4 in fig. 5) outside of transmission burst time window 530 may fail, as shown in example 2 of fig. 5.

Note that in some embodiments, the additional transmission opportunity (e.g., n +4 in fig. 5) for transmitting a different second signal (e.g., SRS) in the reserved first time interval may be outside the transmission burst time window, and in this case, the new LBT should be performed before transmission using the third Msg3 opportunity (slot n +4 in fig. 5). That is, the terminal device 102 transmits a different second signal using the additional transmission opportunity in response to determining that the additional transmission opportunity is available.

In some embodiments, the additional transmission opportunity (e.g., slot n +3 in fig. 5) is after the first available transmission opportunity (e.g., slot n +2 in fig. 5) and within the transmission burst time window 530, and in this case, the terminal device 102 may transmit a different second signal (e.g., SRS) using the additional transmission opportunity as specified by the unlicensed frequency band without determining availability of the additional transmission opportunity via LBT.

Note that the scheduling message received at block 610 may also indicate a transmission format (e.g., MCS) for the transmission and/or frequency resources for the transmission. In some embodiments, the frequency resources used for transmission may be indicated using the "frequency domain resource assignment" information field shown in table 1.

In some embodiments, the transmission format (e.g., MCS) and/or frequency resources indicated in the scheduling message for transmission are applicable for transmission in both the first time interval and the second time interval.

Note that in some embodiments, method 600 may be used to transmit Msg3.Msg3 may be prepared at terminal device 102 prior to actual transmission, and the scrambling of Msg3 may be independent of the slot number/index at which Msg3 is transmitted. That is, regardless of which slot Msg3 is transmitted, the same scrambling is applied to simplify Msg3 generation and avoid preparing multiple versions of Msg3.

In some embodiments, optionally, at block 605, terminal device 102 may receive configuration information for a transmission burst time window (e.g., transmission burst time window 530 in fig. 5) from network device 101. The description of the transmission burst time window provided with reference to method 400, fig. 4, and fig. 5 also applies here. For example, the scheduling message may be received by terminal device 102 during a transmission burst time window. Alternatively or additionally, the reserved first time interval may be within a transmission burst time window and the unreserved second time interval may be outside the transmission burst time window. In some embodiments, the first time interval may include at least a first transmission opportunity within a transmission burst time window and at least a second transmission opportunity outside the transmission burst time window. In some other embodiments, the unreserved second time interval may be between the transmission burst time window 530 and the next transmission burst time window 540, as shown in fig. 5.

Some embodiments of the present disclosure provide a network device, such as network device 101 in fig. 1. The network device 101 includes: means for transmitting a scheduling message to the terminal device, wherein the scheduling message indicates a first time interval reserved for transmissions from the terminal device; and means for detecting a transmission from the terminal device in a first time interval reserved for the transmission and a second time interval not reserved for the transmission. In some embodiments, network device 101 may also include means for determining a transmission burst time window for transmission and reception at network device 101. Note that the descriptions provided with reference to

methods

400 and 600 regarding the scheduling message, the first time interval, and the second time interval also apply here, and details are not repeated.

Some embodiments of the present disclosure provide a terminal device, for example, terminal device 102 in fig. 1. The terminal apparatus 102 includes: means for receiving a scheduling message from a network device, wherein the scheduling message indicates a first time interval reserved for transmissions from a terminal device; means for determining availability of a first time interval for transmission; and means for determining availability of a second time interval not reserved for transmission in response to determining that the first time interval is not available; and means for performing a transmission in the second time interval in response to determining that the second time interval is available. In some embodiments, terminal device 102 may further include means for performing a transmission in the first time interval in response to determining that the first time interval is available. In another embodiment, terminal device 102 may comprise means for receiving configuration information for a transmission burst time window from network device 101. The descriptions provided with respect to the scheduling message, the first time interval, and the second time interval with respect to

methods

400 and 600 also apply here, and details are not repeated.

Fig. 7 shows a simplified block diagram of an apparatus 700, which apparatus 700 may be embodied as or included in a communication device (e.g., terminal device 102 or network device 101 shown in fig. 1).

The apparatus 700 includes at least one processor 711, such as a Data Processor (DP), and at least one memory (MEM) 712 coupled to the processor 711. The apparatus 700 may also include a transmitter TX and receiver RX 713 coupled to the processor 711 and operable to communicatively connect to other apparatuses. The MEM 712 stores a program or computer program code (PROG) 714. The at least one memory 712 and the computer program code 714 are configured to, with the at least one processor 711, cause the apparatus 700 at least to perform, for example, the

method

400 or 600 according to embodiments of the present disclosure.

The combination of the at least one processor 711 and the at least one MEM 712 may form a processing component 715 configured to implement various embodiments of the present disclosure.

Various embodiments of the disclosure may be implemented by computer programs, software, firmware, hardware, or a combination thereof executable by the processor 711.

The MEMs 712 may be of any type suitable to the local technical environment, and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples.

The processor 711 may be of any type suitable to the local technical environment, and may include one or more of the following, as non-limiting examples: general purpose computers, special purpose computers, microprocessors, digital Signal Processors (DSPs) and processors based on a multi-core processor architecture.

Additionally, the present disclosure may also provide a carrier containing a computer program as described above. The carrier includes computer readable storage media and transmission media. The computer-readable storage medium may include, for example, optical or electronic memory devices such as RAM (random access memory), ROM (read only memory), flash memory, magnetic tape, CD-ROM, DVD, blu-ray disc, and the like. Transmission media can include, for example, electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with the embodiments includes not only prior art means but also means for implementing one or more functions of the corresponding apparatus, and the apparatus may include separate means for each separate function or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (e.g., a circuit or processor), firmware, software, or a combination thereof. For firmware or software, implementation can be through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Some example embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatus. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or possible claims, but rather as descriptions of features specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

It is clear to a person skilled in the art that with the advancement of technology, the inventive concept may be implemented in various ways. The above-described embodiments are given for the purpose of illustration and not limitation of the present disclosure, and it is to be understood that modifications and variations may be made without departing from the spirit and scope of the disclosure, as will be readily understood by those skilled in the art. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The scope of the disclosure is defined by the appended claims.

Some abbreviations used in this disclosure and their corresponding descriptions are listed below:

CPDCCH common physical downlink control channel

DL downlink

DMRS demodulation reference signals

gNB next generation node B

LBT listen before talk

LTE Long term evolution

MCS modulation and coding scheme

MF MuLTEFire

Msg message

NR new radio

OFDM orthogonal frequency division multiplexing

PCell primary cell

Physical Random Access Channel (PRACH)

PRB physical resource block

PSCell main and auxiliary cell

RACH random access channel

RAR random access response

RE resource elements

RRC radio resource control

RS reference signal

SCS subcarrier spacing

SRS sounding reference signal

UE user equipment

UL uplink

URLLC ultra-reliable low-delay communication

Claims

1. A network device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the network device at least to:

transmitting a scheduling message to a terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device, the reserved first time interval providing a plurality of transmission occasions for the transmissions from the terminal device;

detecting the transmission in the reserved first time interval; and

in response to failing to successfully detect the transmission in the first time interval, detecting the transmission in a second time interval not reserved for the transmission.

2. The network device of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to detect the transmission in the first time interval by:

detecting a first signal from the terminal device in a first available transmission occasion of the plurality of transmission occasions; and

detecting a different second signal from the terminal device in a further transmission occasion of the plurality of transmission occasions.

3. The network device of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to detect the transmission in an unlicensed frequency band.

4. The network device of claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to:

determining a transmission burst time window for transmission and reception at the network device, an

Transmitting the scheduling message during the determined transmission burst time window.

5. The network device of claim 4, wherein the first time interval is within the transmission burst time window and the second time interval is outside the transmission burst time window.

6. The network device of claim 4, wherein the first time interval provides at least a first transmission opportunity within the transmission burst time window and at least a second transmission opportunity outside of the transmission burst time window.

7. The network device of claim 4, wherein the second time interval is between the transmission burst time window and a next transmission burst time window.

8. The network device of claim 1, wherein the scheduling message further indicates at least one of:

a transmission format for said transmission, and

frequency resources for the transmission.

9. The network device of any of claims 1-8, wherein the transmission comprises a transmission of message 3 for random access.

10. A terminal device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured to, with the at least one processor, cause the terminal device at least to:

receiving a scheduling message from a network device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device, the reserved first time interval providing a plurality of transmission occasions for the transmissions from the terminal device;

determining availability of the first time interval for the transmission;

in response to the first time interval not being available, determining availability of a second time interval not reserved for the transmission; and

performing the transmission in a second time interval not reserved for the transmission in response to the second time interval being available.

11. The terminal device of claim 10, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to perform the transmission in an unlicensed frequency band.

12. The terminal device of claim 10, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to:

in response to determining that the first time interval is available, performing the transmission in the first time interval.

13. The terminal device of claim 10, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to perform the transmission in the first time interval by:

transmitting a first signal using a first available transmission opportunity of the plurality of transmission opportunities; and

transmitting a different second signal using another of the plurality of transmission occasions.

14. The terminal device of claim 13, wherein the first signal comprises message 3 and the second signal comprises a reference signal.

15. The terminal device of claim 13, wherein the further transmission occasion is outside a transmission burst time window, and

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to transmit the different second signals using the further transmission occasions by:

determining availability of the further transmission opportunity via listen-before-talk; and

transmitting the different second signal using the additional transmission opportunity in response to determining that the additional transmission opportunity is available.

16. The terminal device of claim 13, wherein the additional transmission opportunity is subsequent to the first available transmission opportunity and within a transmission burst time window, and

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to perform the transmission in the second time interval by:

postponing the transmission by a predefined time offset in an available transmission opportunity in the second time interval before performing the transmission in the available transmission opportunity.

17. The terminal device of any of claims 10 to 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device to:

receiving configuration information for a transmission burst time window from the network device.

18. The terminal device of claim 17, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the network device to receive the scheduling message during the transmission burst time window.

19. The terminal device of claim 17, wherein the first time interval is within the transmission burst time window and the second time interval is outside the transmission burst time window.

20. The terminal device of claim 17, wherein the first time interval provides at least a first transmission opportunity within the transmission burst time window and at least a second transmission opportunity outside the transmission burst time window.

21. The terminal device of claim 17, wherein the second time interval is between the transmission burst time window and a next transmission burst time window.

22. The terminal device of any of claims 10 to 16, wherein the scheduling message further indicates at least one of:

a transmission format for said transmission, and

frequency resources for the transmission.

23. A network device, comprising:

means for transmitting a scheduling message to a terminal device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device, the reserved first time interval providing a plurality of transmission occasions for the transmissions from the terminal device;

means for detecting the transmission in the reserved first time interval; and

means for detecting the transmission in a second time interval not reserved for the transmission in response to failing to successfully detect the transmission in the first time interval.

24. A terminal device, comprising:

means for receiving a scheduling message from a network device, the scheduling message indicating a first time interval reserved for transmissions from the terminal device, the reserved first time interval providing a plurality of transmission occasions for the transmissions from the terminal device;

means for determining availability of the first time interval for the transmission; and

means for determining availability of a second time interval not reserved for the transmission in response to determining that the first time interval is unavailable; and

means for performing the transmission in the second time interval in response to determining that the second time interval is available.

25. A method in a network device, comprising:

detecting the transmission in the reserved first time interval; and

26. The method of claim 25, wherein detecting the transmission in the reserved first time interval comprises:

27. The method of claim 25, wherein the method is performed in an unlicensed frequency band.

28. The method of claim 25, further comprising:

Wherein transmitting the scheduling message comprises transmitting the scheduling message during the determined transmission burst time window.

29. The method of claim 28, wherein the first time interval is within the transmission burst time window and the second time interval is outside the transmission burst time window.

30. The method of claim 28, wherein the first time interval provides at least a first transmission opportunity within the transmission burst time window and at least a second transmission opportunity outside of the transmission burst time window.

31. The method of claim 28, wherein the second time interval is between the transmission burst time window and a next transmission burst time window.

32. The method of claim 25, wherein the scheduling message further indicates at least one of:

a transmission format for said transmission, and

frequency resources for the transmission.

33. The method of any of claims 25 to 32, wherein the transmission comprises a transmission of message 3 for random access.

34. A method in a terminal device, comprising:

determining availability of the first time interval for the transmission;

determining availability of a second time interval not reserved for the transmission in response to determining that the first time interval is not available; and

in response to determining that the second time interval is available, performing the transmission in the second time interval.

35. The method of claim 34, wherein performing the transmission comprises performing the transmission in an unlicensed frequency band.

36. The method of claim 34, further comprising:

37. The method of claim 34, wherein performing the transmission in the first time interval comprises:

38. The method of claim 37, wherein the first signal comprises message 3 for random access and the second signal comprises a reference signal.

39. The method of claim 37, wherein the additional transmission opportunity is outside a transmission burst time window, and

wherein transmitting the different second signals using the additional transmission occasions comprises:

determining availability of the additional transmission opportunity via listen-before-talk; and

40. The method of claim 34, wherein performing the transmission in the second time interval comprises:

41. The method of any of claims 34 to 40, further comprising:

42. The method of claim 41, wherein receiving the scheduling message comprises receiving the scheduling message during the transmission burst time window.

43. The method of claim 41, wherein the first time interval is within the transmission burst time window and the second time interval is outside the transmission burst time window.

44. The method of claim 41, wherein the first time interval provides at least a first transmission opportunity within the transmission burst time window and at least a second transmission opportunity outside of the transmission burst time window.

45. The method of claim 41, wherein the second time interval is between the transmission burst time window and a next transmission burst time window.

46. The method of any of claims 34 to 40, wherein the scheduling message further indicates at least one of:

a transmission format for said transmission, and

frequency resources for the transmission.

47. A computer-readable medium having stored thereon a computer program which, when executed by an apparatus, causes the apparatus to perform the method of any of claims 25 to 33.

48. A computer readable medium having stored thereon a computer program which, when executed by an apparatus, causes the apparatus to perform the method of any of claims 34 to 46.