CN112292905A - Transmission techniques in cellular networks - Google Patents

Abstract

The present application relates generally to transmission techniques in a cellular network. The transmission technique is particularly applicable to radio systems operating in unlicensed spectrum. The enhanced listen-before-talk procedure prepares one full slot for transmission initiation when transmission resources are acquired. But in that slot only that part of the time remaining in the slot in which the resource is scheduled to be acquired is actually transmitted. A procedure is then provided for transmitting the remaining data in the following time slot.

Description

Transmission techniques in cellular networks

Technical Field

The present application relates to transmission techniques in cellular networks, and more particularly to listening to physical layer techniques in a radio system before a conversation.

Background

Wireless communication systems such as third generation (3G) mobile telephone standards and technologies are well known. Such 3G standards and technologies have been developed by the 3 rd generation partnership project (3 GPP). Third generation wireless communications were developed generally to support macrocell mobile telephone communications. Communication systems and networks have evolved towards broadband and mobile systems.

In a cellular wireless communication system, User Equipment (UE) is connected to a Radio Access Network (RAN) over a radio link. The RAN comprises a set of base stations and an interface to a Core Network (CN). The base station provides a radio link to UEs located in the cell covered by the base station. The core network provides overall network control. It is to be understood that the RAN and CN each perform corresponding functions related to the overall network. For convenience, the term cellular network will be used to refer to the combined RAN and CN. And it is to be understood that the term is used to refer to a corresponding system for performing the disclosed function.

The 3 rd generation mobile communication partnership project has developed a so-called Long Term Evolution (LTE) system, i.e., evolved universal mobile telecommunications system terrestrial radio access network (E-UTRAN). The Long Term Evolution (LTE) system is used for mobile access networks supported by base stations in which one or more macro cells are called enodebs or enbs (evolved nodebs). Recently, LTE has evolved further towards so-called 5G or NR (new radio) systems. In the 5G or NR (new radio) system, one or more cells are supported by a base station called a gNB. NR is proposed to utilize an Orthogonal Frequency Division Multiplexing (OFDM) physical transmission format.

The NR protocol is intended to provide an option for operating in the unlicensed radio band, referred to as NR-U. When operating in the unlicensed radio band, the gNB must contend with other devices for physical medium access. For example, Wi-Fi, NR-U, and LAA can utilize the same physical media resources.

In order to share resources, a listen-before-talk (LBT) protocol is proposed. In listen-before-talk protocols, the gNB monitors the available resources and initiates transmission only when appropriate resources are available. Once LBT is successful (the resource is "seized"), the gNB accesses the resource for up to the Channel Occupancy Time (COT) as long as no transmission interruption occurs for more than a predefined interval (e.g., 16 μ β).

Thus, the gNB may access the physical medium at any point in time, and this access may occur anywhere in the cell with which the slot timing is relevant. However, in conventional systems, transmission can only start at the slot boundary (symbol 0 or 7 of the subframe), which therefore limits the available resources. Even if transmission can start at any symbol boundary, in the slot where medium access is taken, the gNB will only use a few of the symbols in that slot for its UL and DL traffic. Furthermore, until access to the resource is gained through LBT, the gNB does not know that several symbols are available.

Fig. 1 shows an example of a gNB gaining access to a physical medium during a timeslot. At region 100, the gNB listens for access and successfully finds available resources at 101. Thus, the COT 102 available to the gNB spans a portion of the first slot 103, the entire second slot 104, and a portion of the third slot 105.

The gNB may prepare a number of mini-slot transmissions corresponding to the possible number of symbols available for transmission in the first slot, but doing so requires significant processing by the gNB and this only supports some mini-slot lengths (2, 4 or 7 symbols). Alternatively, a series of short mini-slots (2 symbols) may be prepared and used to fill the available symbols after LBT success (as long as there are at least 2 available symbols). However, the 2 nd (and subsequent) mini-slot scheduling must be done within 2 OSs and there is DMRS and DCI overhead within each slot. Also, not all lengths can be covered (2, 4 or 7 symbols).

Therefore, a method for effectively utilizing resources in a partial slot after LBT is successful is required.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

A data transmission method using listen-before-talk (LBT) transmission protocol in a cellular communication network is provided. The method performed at the base station has a predetermined symbol length and timing and a predetermined slot length and timing and comprises the steps of: preparing a transmission slot corresponding to the length of a predetermined slot length, the transmission slot including a data TB; monitoring access to transmission resources and obtaining access to these transmission resources; initiating transmission of a transmission slot to the UE at a first available predetermined symbol boundary after obtaining the transmission resources; receiving a transmission of a transmission slot at a first predetermined slot boundary after initiating the transmission; the TB portion that cannot be transmitted prior to the first predetermined slot boundary is subsequently transmitted in a subsequent slot.

The transmission slots may be transmitted on PDSCH.

The subsequent transmission may depend on CBG-level HARQ feedback.

CBG-level HARQ feedback may indicate an unreceived CBG by indicating the last or first unreceived CBG.

The method may further include the step of activating CBG-level HARQ by RRC messages for at least downlink transmissions on the PDSCH.

Subsequent transmissions may be performed automatically before any HARQ feedback is received.

The transmission slot may be transmitted on the PDSCH with TB level HARQ configured by RRC.

The TB level HARQ feedback may be transmitted by the UE after transmitting the complete TB in more than one individual transmission.

Subsequent transmissions may be in slots that are after but within the same COT as the slot in which the transmission slot begins transmission.

Subsequent transmissions may utilize the same HARQ ID, RV, and NDI as the transmission of the transmission slot.

The transmission slot may include a DCI message for transmission on the PDCCH.

The DCI message on the PDCCH may not be transmitted in the first symbol of the predetermined slot.

A data transmission method using listen-before-talk (LBT) transmission protocol in a cellular communication network is provided. The method performed at the UE has a predetermined symbol length and timing and a predetermined slot length and timing and comprises the steps of: monitoring a PDCCH transmitted from a base station in each symbol until a DCI for a UE is received; receiving a symbol from the base station according to the indication of the DCI, the symbol comprising a first portion of the TB until an end of a slot in which the DCI is received; receiving a second set of symbols comprising a second portion of the TB in a subsequent slot; and assembling the first part and the second part to form a complete TB.

The method may further include the step of transmitting CBG-level HARQ feedback after receiving the first part of the TB.

The method also includes the step of transmitting TB-level feedback after receiving the second portion of the TB.

The symbols may be received on the PDSCH.

A data transmission method using listen-before-talk (LBT) transmission protocol in a cellular communication network is provided. The method performed at the UE has a predetermined symbol length and timing and a predetermined slot length and timing and comprises the steps of: monitoring a PDCCH transmitted from a base station in each symbol until a DCI for a UE is received; transmitting a symbol from the UE to the base station according to the indication of the DCI, the symbol comprising a first portion of the TB until an end of a slot in which the DCI is received; and transmitting a second set of symbols comprising a second portion of the TB in a subsequent slot.

The method may further include the step of receiving CBG-level HARQ feedback from the base station. Where a second set of symbols is transmitted in response to the feedback.

The CBG-level HARQ feedback may indicate the last received CBG in the TB, or the first not received CBG in the TB.

The method may further include the step of receiving TB level HARQ feedback from the base station. In this step, the second part of the TB is transmitted before receiving the feedback.

The symbols and the second set of symbols may be transmitted on the PUSCH.

A data transmission method using listen-before-talk (LBT) transmission protocol in a cellular communication network is provided. The method performed at the base station has a predetermined symbol length and timing and a predetermined slot length and timing and comprises the steps of: preparing a transmission slot corresponding to the length of a predetermined slot length; monitoring access to transmission resources and obtaining access to these transmission resources; initiating transmission of a transmission slot to the UE at a first available predetermined symbol boundary after obtaining the transmission resources, the first symbol comprising DCI corresponding to the transmission slot; receiving, from a UE, a symbol including a first part of a TB in an UL part of a transmission slot; and receiving a symbol including the second part of the TB from the UE in a subsequent transmission slot.

The method may further comprise the step of transmitting CBG-level feedback after receiving the first part of the TB. In this step, the feedback relates to all CBGs of the TB.

The feedback may indicate the last received or first not received CBG of the TB.

The method may further comprise the step of activating CBG-level feedback for PUSCH using RRC messages.

The method may further comprise the step of transmitting TB-level feedback after receiving the second part of the TB.

There is provided a base station configured to perform the above-described related method.

There is provided a UE configured to perform the above-described related method.

The non-transitory computer readable medium may include at least one of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memories, programmable read-only memories, electrically erasable programmable read-only memories, and flash memories.

Drawings

Further details, aspects and embodiments of the present application will be described, by way of example only, with reference to the accompanying drawings. Elements in the figures have been illustrated for simplicity and clarity and have not been drawn to scale. For ease of understanding, like reference numerals are included in the various drawings.

Fig. 1 shows an example of resources in an LBT system;

FIG. 2 illustrates a data transmission method;

fig. 3 and 4 show partial timeslot transmission on the downlink; and

fig. 5 and 6 show partial timeslot transmission on the uplink.

Detailed Description

Those skilled in the art will recognize and appreciate that the specifics of the described examples are merely illustrative of some embodiments and that the teachings set forth in this application are applicable in a variety of alternative settings.

The following disclosure provides a method for using resources in a partial time slot after LBT success. According to the present disclosure, the gbb prepares a regular time slot for transmission. Wherein the slot includes symbols representing a data Transport Block (TB) and DCI. The transmission of the prepared slot is started on the first available symbol after LBT success. That is, the DCI message is transmitted in the first symbol after LBT success (even if the first symbol is not the first symbol of the regular gNB slot timing). The gNB continues transmission of the slot until the next slot boundary is reached (according to the absolute timing of the gNB for regular transmissions, i.e., assuming that transmission begins halfway within the prepared slot until the end of the slot is reached). At this slot boundary, the gNB stops transmitting the prepared slot and goes back to regular transmission aligned with the gNB slot timing.

The gNB then schedules transmission of any remaining TB portions, which could not be transmitted before reaching the gNB gap boundary, either immediately or in subsequent slots. Thus, by fully utilizing the remainder of the gap after LBT success, the method allows all available resources to be utilized in an efficient manner.

Fig. 2 illustrates a method of transmitting data in an LBT system. The process assumes that transmission can be initiated at any symbol boundary within a slot. In the following disclosure, the terms "gNB slot" and "gNB slot boundary" will be used to refer to the conventional slot and boundary timing for the relevant gNB. The term "transmission slot" will be used to refer to a set of symbols prepared for transmission, the transmission slot having a length equal to the gNB slot. The transmission slot may begin to be transmitted at a time determined by the gNB but not necessarily aligned with the gNB slot and the gNB slot boundary.

At step 200, the gbb enables CBG-level HARQ for the relevant gbb/UE connection. CBG-level HARQ is configured through RRC messaging and may be configured independently for dl (pdsch) and ul (pusch). CBG HARQ applies HARQ processes on the CBG level, thus allowing (re-) transmission of only those CBGs that were not transmitted or not properly received within the first gNB slot. This is in contrast to TB level HARQ. In TB level HARQ, HARQ messaging is applied to the entire TB, and the entire TB is retransmitted even though only a single CBG is not received.

In step 201, the gNB prepares a transmission slot for use when the gNB gains access to a transmission resource. Although referred to as a transmission slot, the prepared slot may be a bidirectional slot. This preparation may be done before or in parallel with the gNB performing the LBT procedure at step 202.

Once the gNB gains access to the transmission resources, the gNB initiates transmission of a transmission slot on the PDSCH at a first symbol boundary (step 203). At step 204, the UE monitors the PDCCH in all symbols and, once the PDCCH is detected, applies the received DCI parameters using the received PDCCH start as an initial time reference for the slot.

The transmission of the transmission slot continues until the next gbb slot boundary. At this point, the transmission stops. The gNB goes back to regular transmission scheduling aligned with the gNB slot boundary until the end of the COT.

At step 205, the UE applies CBG feedback to the received and not-received CBGs. At the UE, the CBGs in the transmitted portion of the transmission slot should have been successfully received (or not received due to transmission errors), but those CBGs in the portion of the transmission slot that occurred (falling) after the end of the gNB slot were not transmitted and therefore also not received. The UE therefore transmits HARQ feedback indicating CBGs that have been successfully received and not successfully received.

At step 206, the gNB receives the HARQ feedback and schedules a retransmission of those CBGs that were indicated as not received (but which were actually the first transmissions of some CBGs).

The transmission continues in a conventional manner until the end of the COT, including the transmission of data in the first portion of the time slot is not scheduled (fit). Thus, the method of fig. 2 allows all symbols within a COT to be used without excessive pre-processing or preparation of the transmitted signal in a very short time interval. Although some prepared transmission slots are not finally transmitted, the burden of such preparation is not high and the preparation need not be performed within a very short time scale.

Fig. 3 shows an example time slot using the process of fig. 2. The gNB slot timing is shown at 300. Transmission slot 301 is prepared for transmission and includes CBG 302.

During period 302, the gbb performs the LBT procedure until access is achieved at 303. At symbol 303, the gNB initiates transmission of the prepared transmission slot 301. Transmission of transmission slot 301 stops at the end of the gNB slot 300 and at the end of symbol 4. At this point, the CBGs 304 mapped to symbols 1-4 have been transmitted, but the remaining CBGs 305 have not been transmitted. The HARQ process at step 205 appropriately indicates the transmission state of each CBG. Where the CBG that was not received (305 or any CBG with transmission errors) is indicated as failed. The gNB then reschedules (re) transmission of these CBGs in a conventional manner. The transmission after the end of the gNB slot 300 continues until the end of the COT in the case of the regular slot. Thus, all available resources in the COT are fully utilized.

The transmission of fig. 3 is shown more generally in fig. 4. The first four data symbols 400 of the transmission slot 301 are transmitted in the first gNB slot 300 using PID 1. The transmission in the second gNB slot 401 includes the data scheduled for that slot and may also include CBGs from the transmission slot 301 that were not transmitted in the first gNB slot 300. These CBGs are transmitted using PID1, so the UE can associate them with the CBG received in the first gNB slot 300 and thus compile a complete group of CBGs, i.e., complete TBs.

Fig. 5 shows an example transmission slot 500 including DL 501 and UL 502 regions. In this example, there are enough symbols in the first gNB slot for the first 10 symbols (including the first 4 UL symbols). As shown in fig. 6, the CBG 503 is mapped to those symbols and can therefore be successfully transmitted by the UE to the gNB in the first gNB slot 600. Transmission continues in the second gbb slot 601 using a different PID (PID 2 in this example). The remaining CBGs are scheduled for transmission in subsequent gNB slots 602. In the gNB slot 602, the remaining CBGs are transmitted by the UE using PID1 to combine with the previously transmitted CBGs to form a complete TB.

The method described with reference to fig. 2 thus allows the transmission of the first partial time slot to make full use of the remaining symbols available in the gNB time slot in which LBT was successful. Symbols that fail to be scheduled in the first slot are transmitted by the gNB or UE in subsequent slots within the COT. To enable this procedure, in the first slot, after LBT success, the gNB transmits one DCI, and the UE receives the DCI as if it were transmitted at the gNB slot boundary. Subsequently, the UE and the gbb listen to the gbb slot timing to interrupt transmission at the next gbb slot boundary. After which the regular transmission is used. The CBG HARQ process allows for the identification and (re) transmission of CBGs that were not successfully transmitted and received.

CBG-level HARQ is defined to allow indication of erroneous CBGs that are sparsely distributed within the TBS. However, this does not match well with the types of errors found in the methods disclosed above. In this process, all CBGs after a certain CBG will be lost at the receiver, and the sender will also realize this. Thus, a modified CBG-level HARQ may be implemented, wherein the HARQ acknowledgement message more effectively indicates the not received CBG group for these particular cases. For example, the message may indicate the last successfully received CBG, or the first not received CBG. This implies that all remaining CBGs are not successfully received.

Since the gNB (or UE) knows which CBGs are not transmitted, it can automatically schedule the transmission of these CBGs in the following gNB slots (even in the slot immediately following the first gNB slot in which the transmission slot was partially transmitted). The UE (or the gNB) can then transmit a single HARQ response for the entire TB (TB level HARQ). This technique may improve transmission delay since there is no ACK/NACK ping-pong delay before transmission of CBGs that are not transmitted in the first gNB slot. Furthermore, since only one HARQ message is transmitted for the entire TB, feedback overhead is reduced.

If automatic transmission of the missing CBG (i.e., TB level HARQ) is utilized, the HARQ timing should be set appropriately to allow time for transmission of subsequent CBGs before the HARQ message is sent.

The receiver must be able to identify the CBGs of the subsequent transmissions and combine them with the initial transmission to reassemble the entire TB. To do this, subsequent transmissions must have the same HARQ ID or RV value and must not switch NDI compared to the first transmission. Therefore, when the receiver receives two transmissions having the same HARQ ID, RV, and NDI without sending a HARQ response, it can combine the two transmissions to form a complete TB. Further, the UE can assume that the CBG in the second transmission has the same characteristics as those indicated in the first transmission.

When the automatic transmission of the remaining CBGs is utilized, CBG-level feedback is not needed, and thus CBG-level feedback does not need to be activated for the UE (i.e., step 200 can be omitted from the above-described method). Thus enabling conventional TB-level feedback to be utilized.

CBG-level feedback may be preferable in some situations, for example, when scheduling resources are more limited than traffic resources. CBG-level feedback reduces the timing constraints on the remaining CBG transmissions after the initial partial transmission slot.

Although the above description has been given mainly with respect to DL transmissions, the same principles apply also to uplink transmissions.

The partial TB transmission may be based on a standard CBG retransmission, a modified CBG retransmission (using the modified HARQ message described above), or an implicit/automatic CBG retransmission. Each option has a different overhead. The first two options require CBGTI overhead (overhead) and all increase the CBG overhead for partial transmissions (since CBG is not directly mapped to symbols, partial CBG may be transmitted at the end of the first gNB slot and the entire CBG must be retransmitted).

Compared to a typical unicast 44-bit DCI (+ 16-bit CRC), the signaling overhead corresponds to 6 bits in the DCI (CBGTI is 6 bits). This is negligible compared to the number of bits transmitted in a time slot. The larger the TB, the more negligible it is (shrinkage). For implicit CBG retransmissions, CGBTI is not required, and there is no additional signaling overhead.

The average partial CBG transmission overhead is 0.5 x (CBG length).

It should be noted that the alternative option of multiple minislots has higher DCI overhead because there is one DCI per minislot. This is the case even if the subsequent slot can have compressed DCI and is dependent on the information received in the first DCI. The subsequent mini-slot requires a minimum of-20 bits +16CRC DCI.

The table below lists the efficiency of the proposed technique compared to the pre-formation of mini-slots used to fill part of the slots.

The mean values of the selected parameters are shown in the following table:

the table shows that for the case of SISO, partial TB transmission has at least almost and in many cases better efficiency than the mini-slotted approach (unless only 2 OS are available, which can be considered as an extreme case of low throughput), and the percentage loss is reduced significantly as the MIMO layer is increased, whereas the mini-slotted approach is different.

For example, in the case where the number of layers is 4 and the Codeword (CW) is 1, the resource loss rate is kept below 7% for all periods, while the resource loss rate in the mini-slot method can reach 33%.

The average percentage resource loss for the mini-slot method is 13.9%, while for the case of 1, 2 and 4 MIMO layers the average percentage resource loss for partial TB transmission is 6.7%, 3.4% and 1.7%, respectively.

Thus, the disclosed method provides an efficient way of utilizing transmission resources. In this method, the LBT procedure gains access to the transmission medium partway through the gNB slot.

In the above description, transmission starts at the boundary of the first symbol after gaining access to the transmission resource. However, the transmission may be delayed for any reason, so the transmission may be initiated later. So it can be said that the transmission starts at the first available symbol boundary after gaining access.

Although not shown in detail, any device or apparatus forming part of a network may include at least one processor, a memory unit, and a communication interface. Wherein the processor unit, the memory unit and the communication interface are configured to perform the method of any aspect of the present application. Further options and choices are described below.

The signal processing functions of the embodiments of the present application (particularly the gNB and the UE) may be implemented using computing systems or architectures known to those skilled in the art. Computing systems such as desktop, laptop or notebook computers, handheld computing devices (PDAs, cell phones, palmtops, etc.), mainframes, servers, clients, or any other type of special or general purpose computing device as may be desirable or appropriate for a given application or environment can be used. The computing system may include one or more processors. The processor may be implemented using a general-purpose or special-purpose processing engine. Such as a microprocessor, microcontroller or other control module.

The computing system may also include a main memory (e.g., Random Access Memory (RAM) or other dynamic memory) to store information and instructions to be executed by the processor. The main memory may also be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor. The computing system may also include a Read Only Memory (ROM) or other static storage device for storing static information and instructions for the processor.

The computing system may also include an information storage system. The information storage system may include, for example, a media drive and a removable storage interface. The media drive may include a drive or other mechanism to support fixed or removable storage media, such as a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a Compact Disc (CD) or Digital Video Drive (DVD), a read-write drive (R or RW), or other removable or fixed media drive. The storage media may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD or DVD, or other fixed or removable medium that can be read by and written to by a media drive. The storage media may include a computer-readable storage medium having stored therein particular computer software or data.

In alternative embodiments, the information storage system may include other similar components for allowing computer programs or other instructions or data to be loaded into the computer system. Such components may include, for example, removable storage units and interfaces, such as program cartridges and cartridge interfaces, removable memory (e.g., flash memory or other removable memory modules) and memory slots, and other removable storage units and interfaces. The interface allows software and data to be transferred from the removable storage unit to the computing system.

The computing system may also include a communications interface. Such communication interfaces can be used to allow software and data to be transferred between the computing system and external devices. Examples of communication interfaces may include modems, network interfaces (e.g., ethernet or other NIC cards), communication ports (e.g., Universal Serial Bus (USB) ports), PCMCIA slots and cards, and the like. Software and data transferred via the communication interface are in the form of signals. The signal can be an electronic signal, an electromagnetic signal, an optical signal, or other signal capable of being received by the communication interface medium.

In this document, the terms "computer program product," "computer-readable medium," and the like may be used generally to refer to tangible media, such as memory, storage devices, or storage units. These and other forms of computer-readable media may store one or more instructions for use by a processor, including a computer system, to cause the processor to perform specified operations. These instructions, which are generally referred to as "computer program code" (which may be grouped in the form of computer programs or otherwise), when executed, enable the computing system to perform the functions of embodiments of the present application. Note that the code may directly cause the processor to perform specified operations, be compiled to cause the processor to perform specified operations, and/or be combined with other software, hardware, or firmware elements (e.g., libraries for performing standard functions) to cause the processor to perform specified operations.

The non-transitory computer readable medium may include at least one of: hard disks, CD-ROMs, optical storage devices, magnetic storage devices, read-only memories, programmable read-only memories, electrically erasable programmable read-only memories, and flash memories. In embodiments in which the elements are implemented using software, the software may be stored in a computer-readable medium and loaded into the computing system using, for example, a removable storage drive. When executed by a processor in a computer system, the control module (in this example, software instructions or executable computer program code) causes the processor to perform the functions of the present application as described herein.

Furthermore, the concepts of the present application can be applied to any circuit that performs a signal processing function within a network element. For example, it is also contemplated that a semiconductor manufacturer may employ the concepts of the present application in the design of a stand-alone device (e.g., a microcontroller of a Digital Signal Processor (DSP)) or an Application Specific Integrated Circuit (ASIC) and/or any other subsystem element.

It should be appreciated that the above description, for clarity, describes embodiments of the application with reference to single processing logic. However, the inventive concept may equally be implemented by a plurality of different functional units and processors to provide the signal processing functionality. Hence, references to specific functional units are only to be seen as references to suitable means for providing the described functionality, and not indicative of a strict logical or physical structure or organization.

Aspects of the present application may be implemented in any suitable form including hardware, software, firmware or any combination of these. The present application may optionally be implemented at least in part as computer software. The computer software may be run on one or more data processors and/or digital signal processors or configurable element modules such as FPGA devices.

Thus, the elements and components of an embodiment of the application may be physically, functionally and logically implemented in any suitable way. Indeed the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. Although the present application has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. The scope of the application is limited only by the claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the application. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Likewise, the inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate.

Furthermore, the order of features in the claims does not imply that the features must be performed in any particular order. Especially the order of individual steps in the method claims does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. Furthermore, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second", etc., do not preclude a plurality.

Although the present application has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. The scope of the application is limited only by the claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the application. In the claims, the term "comprising" or "comprises" does not exclude the presence of other elements.

Claims (28)

1. A data transmission method in a cellular communication network using Listen Before Talk (LBT) transmission protocol, said method performed at a base station having a predetermined symbol length and timing and a predetermined slot length and timing and comprising the steps of:

preparing a transmission slot corresponding to the length of the predetermined slot length, the transmission slot including a data TB;

monitoring access to transmission resources and obtaining access to these transmission resources;

initiating transmission of the transmission slot to a UE at a first available predetermined symbol boundary after the transmission resource is obtained;

ending transmission of said transmission slot at a first predetermined slot boundary after transmission is initiated;

subsequently transmitting in a subsequent slot a portion of the TB that could not be transmitted prior to the first predetermined slot boundary.

2. The method of claim 1, wherein the transmission time slot is transmitted on a PDSCH.

3. The data transmission method according to claim 1 or 2, characterized in that the subsequent transmission depends on CBG-level HARQ feedback.

4. The data transmission method of claim 3, wherein the CBG-level HARQ feedback indicates an unreceived CBG by indicating a last received or a first unreceived CBG.

5. A data transmission method according to claim 2 or 3, further comprising the step of activating CBG-level HARQ for downlink transmission on at least PDSCH by means of RRC messages.

6. A data transmission method according to claim 1 or 2, characterized in that the subsequent transmission is performed automatically before any HARQ feedback is received.

7. The data transmission method of claim 6, wherein the transmission slot is transmitted on a PDSCH configured with TB level HARQ by RRC.

8. The data transmission method of claim 7, wherein the TB level HARQ feedback is transmitted by the UE after a full TB is transmitted in more than one separate transmission.

9. The data transmission method according to any of the preceding claims, wherein the subsequent transmission is performed in a time slot that is located after the time slot in which the transmission slot starts transmitting but within the same COT as the time slot in which the transmission slot starts transmitting.

10. The data transmission method according to any of the preceding claims, wherein the subsequent transmission utilizes the same HARQ ID, RV and NDI values as the transmission of the transmission slot.

11. The data transmission method according to any of the preceding claims, wherein the transmission slot comprises a DCI message for transmission on the PDCCH.

12. The data transmission method of claim 11, wherein the DCI message on the PDCCH is not transmitted on the first symbol of a predetermined slot.

13. A data transmission method in a cellular communication network using Listen Before Talk (LBT) transmission protocol, said method performed at a UE having a predetermined symbol length and timing and a predetermined slot length and timing and comprising the steps of:

monitoring a PDCCH transmitted from a base station in each symbol until a DCI for the UE is received;

receiving a symbol from the base station, the symbol comprising a first portion of a TB until an end of a slot in which the DCI is received, in accordance with the indication of the DCI;

receiving a second set of symbols comprising a second portion of the TB in a subsequent slot; and

assembling the first part and the second part to form a complete TB.

14. The data transmission method of claim 13, further comprising the step of transmitting CBG-level HARQ feedback after receiving the first portion of the TB.

15. The data transmission method of claim 13, further comprising the step of transmitting TB-level feedback after receiving the second portion of the TB.

16. The data transmission method of claim 13, wherein the symbols are received on the PDSCH.

17. A data transmission method in a cellular communication network using Listen Before Talk (LBT) transmission protocol, said method performed at a UE having a predetermined symbol length and timing and a predetermined slot length and timing and comprising the steps of:

monitoring a PDCCH transmitted from a base station in each symbol until a DCI for the UE is received;

transmitting a symbol from the UE to the base station according to the indication of the DCI until an end of a slot in which the DCI is received, the symbol comprising a first portion of a TB; and

transmitting a second set of symbols comprising a second portion of the TB in a subsequent slot.

18. The method of claim 17, further comprising the step of receiving CBG-level HARQ feedback from the base station, wherein the second set of symbols are transmitted in response to the feedback.

19. The method of claim 18, wherein the CBG-level HARQ feedback indicates a last received CBG in the TBs or a first not received CBG in the TBs.

20. The method of claim 18, further comprising the step of receiving TB level HARQ feedback from the base station, wherein the second portion of the TB is transmitted prior to receiving the feedback.

21. The method according to any of claims 17 to 20, wherein the symbols and the second set of symbols are transmitted on the PUSCH.

22. A data transmission method in a cellular communication network using Listen Before Talk (LBT) transmission protocol, said method performed at a base station having a predetermined symbol length and timing and a predetermined slot length and timing and comprising the steps of:

preparing a transmission slot corresponding to the length of the predetermined slot length;

monitoring access to transmission resources and obtaining access to these transmission resources;

initiating transmission of the transmission slot to a UE at a first available predetermined symbol boundary after obtaining the transmission resource; the first symbol includes DCI corresponding to the transmission slot;

receiving, from the UE, a symbol comprising a first portion of a TB in an UL portion of the transmission slot; and

receiving, from the UE, a symbol including the second portion of the TB in a subsequent transmission slot.

23. The method of claim 21, further comprising the step of transmitting CBG-level feedback after receiving the first portion of the TB, wherein the feedback relates to all CBGs of the TB.

24. The method of claim 22, wherein the feedback indicates a last received or a first not received CBG for the TB.

25. The method according to claim 22 or 23, further comprising the step of activating CBG level feedback for the PUSCH using an RRC message.

26. The method of claim 21 further comprising the step of transmitting TB-level feedback after receiving the second portion of the TB.

27. A base station configured to perform the method of any one of claims 1 to 12 and 22 to 26.

28. A UE configured to perform the method of any of claims 13 to 21.

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