CN111213421A

CN111213421A - Time slot aggregation

Info

Publication number: CN111213421A
Application number: CN201880050723.9A
Authority: CN
Inventors: 赛巴斯钦·华格纳; 欧麦尔·萨利姆; 布鲁诺·杰裘克斯
Original assignee: Jiekai Communications Shenzhen Co Ltd
Current assignee: JRD Communication Shenzhen Ltd; Jiekai Communications Shenzhen Co Ltd
Priority date: 2017-08-11
Filing date: 2018-08-09
Publication date: 2020-05-29
Also published as: WO2019029592A1; GB201712895D0; GB2565344B; GB2565344A

Abstract

Method and system for aggregating mini-slots in an OFDM transmission system, mini-slots being aggregated in the time and/or frequency domain and used for transmitting data, the aggregation may allow configuring the DMES transmission to adapt to overhead and channel conditions.

Description

Time slot aggregation

Technical Field

The present application relates to aggregation of mini-slots (mini-slots) in a wireless communication system.

Background

Wireless communication systems, such as third generation (3G) mobile telephone standards and techniques are well known. The 3G standards and technologies were developed by the Third Generation Partnership Project (3 GPP). Third generation wireless communications were developed to support macro cellular mobile telephone communications. Communication systems and networks are evolving towards broadband mobile systems.

The third generation partnership project has developed a so-called Long Term Evolution (LTE) system, i.e., an Evolved Universal terrestrial Radio Access Network (E-UTRAN), in which one or more macrocells are supported by a base station eNodeB or eNB (Evolved NodeB). Recently, LTE has further evolved towards so-called 5G or NR (New Radio technology) systems, in which one or more macrocells are supported by a base station gN.

NR proposes an OFDM transmission format for the system radio link. OFDM systems use a number of subcarriers spaced apart in frequency, each subcarrier being independently modulated. Demodulation of the subcarrier sets allows recovery of the signal. Slots are defined for scheduled transmissions, each slot comprising a number of OFDM symbols. NR suggests using 7 or 14 OFDM symbols per slot. The subcarriers or frequency resources within each time slot may be used to transmit one or more channels over the link. Likewise, each time slot may contain all uplink, all downlink, or mixed direction links.

NR also proposes mini-slots (TR 38.912) comprising 1 to (slot length-1) OFDM symbols to improve scheduling flexibility. Each mini-slot may start from any OFDM symbol in the slot (assuming that resources are not pre-allocated to the channel, e.g., PDCCH). Some configurations may be limited to systems in excess of 6GHz or to a minimum mini-slot length of 2 OFDM symbols.

5G proposes a series of services including enhanced mobile Broadband (eMBB) for high data rate transmission, Ultra-Reliable Low-delay Communication (URLLC) for Low-delay and high-link-reliability devices, and massive machine-Type Communication (mMTC) to support a large number of Low-power devices for long-term demand for high-efficiency energy Communication.

TR 38.913 defines the delay as "the time required to successfully send an application layer data packet/message from the ingress of a radio protocol layer 2/3SDU to the egress of a radio protocol layer 2/3SDU over the uplink and downlink radio interfaces". For URLLC, the user plane delay (user plane latency) is targeted to be 0.5ms for Uplink (UL) and 0.5ms for Downlink (DL).

TR 38.913 defines reliability as "reliability can be evaluated by the success rate of transmitting X bytes within a certain delay, which is the time required to send a small packet from the radio protocol layer 2/3SDU entry to the radio protocol layer 2/3SDU exit within a certain channel quality (e.g., coverage-edge"). For URLLC, the reliability requirement for one transmission of a data packet defines 32 bytes as 1 × 10^-5And the user plane delay is 1 ms.

The present application seeks to address the issue of efficient use of mini-slots for providing eMBB and URLLC services.

The present application is seeking to solve at least some of the outstanding problems in the art.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that 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.

The application provides a method for data transmission between a base station and a UE in a cellular communication system by using an OFDM modulation format, which comprises the following steps: defining a DMRS transmission pattern for a mini-slot, such that the DMRS is transmitted in a plurality of OFDM symbols in the mini-slot; transmitting the mini-slot from the base station to the UE, the mini-slot including a defined DMRS pattern.

The DMRS transmission pattern in a mini-slot may be transmitted to a UE in an associated DCI.

The DCI may be transmitted on the PDCCH of the slot in which the mini-slot is located.

The DCI may be transmitted on a PDCCH that is part of the mini-slot.

The DMRS transmission pattern may be transmitted to the UE using higher layer signaling, in particular RRC signaling.

The DMRS transmission mode may be described as a periodic indication.

The DMRS transmission pattern may be described as an indication that multiple DMRS are transmitted in one mini-slot.

The transmission mode may be selected from the transmission mode table based on a system configuration.

The present application further provides a method for data transmission between a base station and a UE in a cellular communication system using an OFDM modulation format, the method comprising: defining a DMRS for transmission on an OFDM symbol of a mini-slot, wherein the DMRS does not use all frequency resources of the OFDM symbol; applying a cyclic shift to the DMRS to generate the DMRS for antenna ports on which the OFDM symbol is to be transmitted, wherein each port applies a different cyclic shift; transmitting a mini-slot through an antenna port corresponding to the applied cyclic shift, the mini-slot including the cyclically shifted DMRS.

The DMRS may use pairs of adjacent frequency resources, with an orthogonal cover code applied in each pair of adjacent frequency resources.

The interval between DMRS signals in the frequency domain may be transmitted by the base station to the UE.

The spacing between DMRS signals may be transmitted in DCI.

The interval between DMRS signals may be transmitted using higher layer signaling, in particular RRC signaling.

The method may include: adjusting DMRS power relative to data OFDM symbol power based on a proportion of resources used by the DMRS such that the DMRS power increases as the used resources decrease.

An embodiment of the present application further provides a method for performing data transmission between a base station and a UE in a cellular communication system by using an OFDM modulation format, where the method includes: defining a DMRS for transmission on an OFDM symbol of a mini-slot, wherein the DMRS does not use all frequency resources of the OFDM symbol; wherein a subset of frequency resources used by the DMRS is suitable for transmission through a first antenna port, and a second discrete subset of frequency resources used by the DMRS is suitable for transmission through a second antenna port, such that one OFDM symbol transmits DMRS for at least two antenna ports; a cyclic shift is applied to the DMRS to generate the DMRS for a second set of antenna ports on which the OFDM symbol is to be transmitted.

The non-transitory computer readable storage medium may include at least one of a hard disk, a Compact disc Read Only Memory (CD-ROM), an optical Memory, a magnetic Memory, a Read Only Memory (ROM), a Programmable Read Only Memory (PROM), an Erasable Programmable Read Only Memory (EPROM), an Electrically Erasable Programmable Read Only Memory (EEPROM), and a Flash Memory.

Drawings

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Elements in the figures have been simplified and are not necessarily drawn to scale. For ease of understanding, reference numerals have been included in the various figures.

FIG. 1 is an exemplary diagram of a mini-slot;

fig. 2 is an exemplary diagram of URLLC scheduling;

FIG. 3 is an exemplary diagram of intra-slot aggregation;

FIG. 4 is an exemplary diagram of aggregation within non-contiguous timeslots;

FIG. 5 is an exemplary diagram of aggregation within non-contiguous and contiguous time slots;

fig. 6 is an exemplary diagram of URLLC frequency domain aggregation;

FIG. 7 is an exemplary diagram of inter-slot (inter-slot) aggregation;

fig. 8 is an exemplary diagram of combining intra-slot aggregation and inter-slot aggregation.

Detailed Description

The embodiments described herein are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The present application presents systems and methods for using mini-slots in NR systems to improve efficiency. Mini-slots may carry services through aggregation and provide flexibility for the carrying of control channels.

The following description is given in the context of a cellular communication system comprising land-based network (land-based network) components and remote User Equipment (UE), in particular relating to the radio channel between a land network base station and the UE, with transmissions from the base station to the UE being in the downlink direction and transmissions from the UE to the base station being in the uplink direction. The base station may include, or be connected to, a gNB that performs network management and control functions.

Fig. 1 is a schematic diagram of a slot including 14 OFDM symbols. The PDCCH is carried by the first OFDM symbol and the PDCCH channel of the slot includes control and scheduling information (in DCI). However, in some particular embodiments, the scheduled transmission may later be preempted by further PDCCH transmissions in the time slot (e.g., as described below with respect to fig. 2).

The remaining 13 symbols may be used for the bearer of the PDSCH. In fig. 1, 3 mini-slots are defined to carry data on PDSCH. Each mini time slot adopts different time domain resources and frequency domain resources according to the requirement of carrying data. The first OFDM symbol of each mini-slot includes a Demodulation Reference Signal (DMRS). Multiple UEs may be scheduled in each mini-slot, if desired.

Fig. 2 is a diagram of an example of a transmission for a URLLC service providing ultra-low latency. As shown in fig. 1, the scheduling information is transmitted in the PDCCH of the slot and defines and transmits a first mini-slot 200. However, the second mini-slot 201 is defined by a further PDCCH transmission to define a mini-slot that preempts the traffic (traffic) originally scheduled for the resource in which the second mini-slot is located. In the first OFDM symbol of the second mini-slot, the PDCCH and DMRS are transmitted, followed by the PDSCH of the mini-slot in the second OFDM symbol. Traffic initially scheduled for preemptive locations must be rescheduled in later time slots.

In the following description, mini-slots may be aggregated to provide a more efficient data bearer. Aggregating mini-slots may reduce control overhead (overhead) because one DCI may schedule multiple mini-slots, and aggregating mini-slots may allow time and frequency diversity (time and frequency diversity) to improve channel quality. The aggregation of mini-slots may also better control the placement of DMRSs, depending on the requirements to allow the gNB to adjust DMRS position and/or density.

The description given below refers to two principle families of polymerization, continuous and discontinuous, the principles described herein apply to the general case and are not limited to any particular example. Aggregation refers to grouping of multiple mini-slots and allocating data for transmission on groups of mini-slots (e.g., one or more transport blocks) rather than being allocated to a single mini-slot. One TB is mainly mapped to all mini-slots in the aggregation. However, for spatial multiplexing, multiple TBs may be mapped to an aggregated mini-slot. As described in various embodiments, mini-slots in a single slot (aggregation within a slot) may be aggregated, or mini-slots in multiple slots (aggregation between slots) may be aggregated

Fig. 3 shows the slots used to transmit three sets of consecutive aggregated mini-slots. Continuous aggregation describes a configuration in which mini-slots are transmitted on consecutive OFDM symbols using the same frequency range. The aggregation 300 includes 3 mini-slots, each of which is 2 OFDM symbols in length, the aggregation 301 includes 2 mini-slots having 3 OFDM symbols, and the aggregation 302 includes 4 mini-slots having 3 OFDM symbols.

Each DMRS is transmitted in the first OFDM symbol of each mini-slot, such that each aggregation carries multiple DMRS signals. In principle, DMRS can be located anywhere, but the current NR scheme is transmitted in the first OFDM symbol.

Aggregation of multiple mini-slots, each carrying a DMRS, to allow the system to define DMRS intervals (in the time domain) according to system requirements. The long mini-slots result in larger intervals between DMRS signals, while the short mini-slots result in smaller intervals. For example, if it is determined that the channel only slowly changes over time, a long mini-slot may be used to increase the DMRS interval. Likewise, for a given channel coherence time, increasing the subcarrier spacing shortens the OFDM symbol. DMRS can be spaced apart by a greater number of mini-slots, corresponding to the same spacing in the time domain.

Typically, the location and size of each mini-slot is indicated in the DCI of the PDCCH bearer at the beginning of each slot, although the mini-slots that some services may use are defined after the PDCCH transmission of the slot. This can be accomplished by indicating the start position and length, or start position and end position, of each mini-slot. The use of aggregation also requires the assignment of aggregation levels.

Any suitable mechanism may be used to specify these parameters, three examples of which are provided below.

In a first example, the start position of each aggregation may be indicated, as well as the length of the mini-slots in each aggregation and the number of mini-slots of the aggregation. Fig. 3 may be represented as:

	302	301	300
				starting position	1	8	1
Length of	3	3	2
				Grade of polymerization	4	2	3

In a second example, the start position of each aggregation may be indicated, as well as the end position of the first mini-slot of each aggregation and the number of mini-slots of the aggregation. Fig. 3 may be represented as:

	302	301	300
				starting position	1	8	1
End position	3	10	2
				Grade of polymerization	4	2	3

In a third example, the start position of each aggregation may be indicated, as well as the end position of each aggregation and the number of mini-slots of the aggregation. Fig. 3 may be represented as:

	302	301	300
				starting position	1	8	1
End position	12	13	6
				Grade of polymerization	4	2	3

Each example provides the UE with sufficient information to reconstruct the required mini-slot structure so that the signal can be received and decoded. Other configuration methods may also be used, e.g., the gNB may configure the UE using higher layer signaling (higher layer signaling) to indicate that the UE should use a predefined aggregation level in a semi-static manner (semi-static manager).

Continuous aggregation in the frequency domain can be achieved, but it does not allow flexible placement of DMRSs.

FIG. 4 shows a number of examples of non-contiguous mini-slot aggregation. For non-contiguous aggregation, there is at least one OFDM symbol between each successive mini-slot allocated to the aggregation. Each example of fig. 4 shows the transmission of mini-slots for three UEs, but each mini-slot may also be used for a different data channel for a single UE.

In fig. 4(a), the aggregation of each mini-slot is not contiguous in the time domain. This demonstrates the above advantages, allowing for better DMRS transmission intervals to be defined, and may also benefit from the time domain diversity of the wireless channel, since the mini-slots are more spaced in the time domain (which allows for larger DMRS intervals to reduce the gain in time domain diversity, although the channel varies slowly). In fig. 4(b), the aggregation of each mini-slot is non-contiguous in the frequency domain, providing frequency domain diversity over the wireless channel. Finally, in fig. 4(c), each aggregation is non-contiguous in the time and frequency domains.

If the gNB has information about the radio channel performance (in the frequency domain and/or in the time domain), it may choose to arrange each mini-slot to try to optimize the channel. For example, if the channel varies rapidly in the time domain, time domain diversity is preferably employed, but if the channel has strong frequency fading (frequency fading), frequency domain diversity is preferably employed.

As discussed in fig. 3, the mini-slots and the location of aggregation may be transmitted in the DCI of the PDCCH using similar techniques as in the above example. For example, the gNB may semi-statically configure mini-slots and aggregation using RRC or other higher layer signaling.

The combined use of continuous and discontinuous polymerization also makes it possible to combine the advantages mentioned above. Fig. 5 shows an aggregation of four mini-slots. The two sets of two

mini-slots

500, 501 are consecutively aggregated in the time domain, and the two

sets

500, 501 are non-consecutively aggregated in the time and frequency domains. This arrangement may indicate the use of an additional field (additional field) in the DCI, e.g. indicating the number of consecutive aggregations to be used and the mode of non-consecutive aggregation.

The aggregation techniques described above may be applied in mini-slots that are scheduled after the DCI of a slot and preempt scheduled transmissions. For example, URLLC transmissions may preempt other transmissions due to the low latency requirements of URLLC services.

For URLLC, either continuous aggregation or non-continuous aggregation may be used in the time domain, but non-continuous aggregation may be disadvantageous because delay may increase. Thus, non-contiguous frequency domain aggregation may be more advantageous, as shown in fig. 6. For a preempted mini-slot, the PDCCH must be sent within that mini-slot. In the example of fig. 6, the PDCCH is transmitted in one aggregated mini-slot because it provides sufficient capacity to indicate the aggregation configuration. The other mini-slots include the DMRS in the second OFDM system, but do not include the PDCCH.

The aggregation of preempting mini-slots may be less advantageous because it may increase interference with other traffic, but non-continuous aggregation may also be used to accommodate transmissions around other ongoing transmissions to reduce preemption.

The above discussion is about aggregation of a single slot, but aggregation may also be performed in multiple slots, which may be referred to as intra-slot aggregation and inter-slot aggregation. Scheduling must avoid interfering with the PDCCH (which may be of different lengths).

As described above, mini-slots of multiple slots may be aggregated. The resource allocation in each time slot may be the same or different. For example, a frequency-hopping pattern (frequency-hopping pattern) may be defined for each UE such that frequency resources of each mini-slot vary according to the pattern.

Fig. 7 shows an example of aggregating mini-slots in a plurality of slots. In this example, three mini-slots using different frequency resources are aggregated for UE1 and three mini-slots using the same frequency resources are aggregated for UE 2.

The frequency resource pattern of the UE1 in fig. 7 is shown as an example only, and any suitable pattern may be used. Likewise, mini-slots do not need to use the same time domain resources in each slot, which may be different. For example, the time domain resources and the frequency domain resources may be selected according to channel performance, or the resources may be fully utilized. The resources may be defined dynamically, or the gNB may define a time-frequency hopping (time-frequency hopping) pattern for each UE through higher layer signaling (or other communication means). Further, the mini-slots need not be from contiguous slots, but may be from non-contiguous slots.

Intra-slot aggregation of mini-slots may also be aggregated by inter-slot aggregation. For example, the example of intra-slot aggregation in fig. 5 may be aggregated over N slots. That is, intra-slot aggregation repeats every kth slot of the N aggregated slots. Fig. 8 shows that UE2 is scheduled with intra-slot aggregation of 4 mini-slots and inter-slot aggregation of 3 slots (N-3, K-1), where the same resources are allocated within each slot. The UE1 is scheduled using intra-discontinuous-slot mini-slot aggregation and inter-slot aggregation between 3 slots, where the intra-slot aggregation resources are the same for every 2 nd slot (N-3, K-2).

By indicating the aggregation number, inter-slot aggregation of mini-slots may be configured in DCI. The time-frequency hopping pattern of inter-slot aggregation may be signaled to the UE by higher layer signaling, or may be dynamically configured in DCI.

As described above, each mini-slot in the aggregation has the same length. However, to provide greater flexibility, the scheduling information may include additional indications to indicate that one or more mini-slots in the aggregate set have different lengths. For example, a flag (flag) may indicate that the last mini-slot has one additional OFDM symbol. Although the signaling overhead may increase, each mini-slot in the aggregation may also be defined using a specific length, thus the structure of the aggregation allows full flexibility.

Although it is not described in detail that any device or apparatus forming part of a network may include at least one processor, memory unit, and communication interface, the processor, memory unit, and communication interface are configured to perform the methods of any aspect of the present application. Further options will be described below.

The signal processing functions in the embodiments of the present application, particularly the signal processing capabilities of the gNB and the UE, may be implemented by computing systems or architectures that are well known to those skilled in the art. The computing system may be a desktop, laptop or notebook computer, hand-held computing device (PDA, cell phone, palmtop, etc.), mainframe, server, client, or any other type of special or general purpose computing device as may be satisfactory or applicable to a given application or environment. The computing system may include one or more processors that may execute a general or special purpose processing engine such as, for example, a microprocessor, microcontroller or other control module.

The computing system may also include a main memory, such as a Random Access Memory (RAM) or other dynamic memory, for storing 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 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 execution by the processor.

The computing system may also include an information storage system including, 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 disk drive (CD) or Digital Video Drive (DVD) read-write drive (R or RW), or other fixed or removable media drive. The storage medium may include, for example, a hard disk, floppy disk, magnetic tape, optical disk, CD, DVD, or other fixed or removable medium that is read by and written to by a media drive. The storage media may include a computer-readable storage medium having stored thereon 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 computing system. These components may include, for example, a removable storage unit and interface, such as a program cartridge and cartridge interface, a removable memory (e.g., a flash memory or other removable memory module) and memory slot, and other removable storage units and interfaces that allow software and data to be transferred from the removable storage unit to the computing system.

The computing system may also include a communication interface. The communication interface may be used to allow software and data to be transferred between the computing system and external devices. For example, the communication interfaces can include a modem, a network interface (such as an Ethernet or other network card), a communication port (such as a Universal Serial Bus (USB) port), a PCMCIA slot and card, and the like. Software and data transferred via the communications interface are in the form of signals which may be electronic, electromagnetic, optical or other signals capable of being received by the communications interface medium.

In this application, the terms "computer program product," "computer-readable medium," and the like are 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 other groupings), when executed, enable the computer system to perform functions of embodiments of the present application. It is noted that the code may directly cause the processor to perform specified operations, may be compiled to do so, and/or may be combined with other software, hardware, and/or firmware elements (e.g., libraries for performing standard functions) to do so.

The non-computer readable medium may comprise at least one from the group of: hard disks, Compact disk Read Only memories (CD-ROMs), optical storage devices, magnetic storage devices, Read Only Memories (ROMs), Programmable Read Only Memories (PROMs), Erasable Programmable Read Only Memories (EPROMs), Electrically Erasable Programmable Read Only Memories (EEPROMs), and flash memories (flashmemories).

In embodiments implemented by software, the software may be stored in a computer-readable medium and loaded into the computing system using, for example, a removable storage drive. A control module (e.g., software instructions or executable computer program code) executed by a processor in a computer system causes the processor to perform functions as described herein.

Further, the present application may be applied in any circuit for performing signal processing functions in a network element. For example, it is further contemplated that a semiconductor manufacturer may employ the innovative concepts in the design of a stand-alone device, which may be a microcontroller (DSP) of a digital signal processor, an Application Specific Integrated Circuit (ASIC), and/or any other subsystem element.

For clarity of description, the foregoing description has described embodiments of the present application with reference to a single processing logic. However, the present application may equally well implement signal processing functions by means of a plurality of different functional units and processors. Thus, references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical, 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 partly, as computer software, a computer software component, such as an FPGA device, running on one or more data processors and/or digital signal processors or configurable modules. 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 with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present application, and the scope of the present application is defined by the following claims. Furthermore, while descriptions of features related to particular embodiments may appear, one skilled in the art may, in light of the present disclosure, appreciate various features of such embodiments. In the claims, the term "comprising" does not exclude the presence of other elements or steps.

Further, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Furthermore, although different features may comprise different claims, these may possibly advantageously be 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 set of claims does not imply a limitation to this set of claims, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

Further, the ordering of features in the claims does not imply that the features must be performed in a particular order, and in particular the order of individual steps in a method claim 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, the singular forms "a", "an", "first", "second", etc. do not exclude the plural forms.

Although the present application has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present application, and the scope of the present application is defined by the following claims. Furthermore, while descriptions of features related to particular embodiments may appear, one skilled in the art may, in light of the present disclosure, appreciate various features of such embodiments. In the claims, the term "comprising" or "including" does not exclude the presence of other elements.

Claims

1. A method for downlink data transmission from a base station to a user equipment, UE, in a cellular communication system using an OFDM modulation format, the method comprising:

defining a plurality of mini-slots, each mini-slot comprising one or more OFDM symbols;

aggregating a plurality of defined mini-slots into a mini-slot aggregation;

transmitting, by the base station to the UE, a scheduling indication of the mini-slot aggregation;

mapping the transmitted data into the mini-slot aggregation;

transmitting mapping data in the mini-slots according to the scheduling.

2. The downlink data transmission method according to claim 1, wherein the aggregated mini-slots are consecutive in a time domain.

3. The method according to claim 1 or 2, wherein the aggregated mini-slots are consecutive in the frequency domain.

4. The method of claim 1, wherein the aggregated mini-slots are non-contiguous in time domain.

5. The method according to claim 1 or 4, wherein the aggregated mini-slots are non-contiguous in the frequency domain.

6. The method according to any one of claims 1 to 5, wherein each mini-slot includes the DMRS in the first OFDM symbol.

7. The downlink data transmission method according to claim 4, wherein the aggregation is defined according to a repetition rate required for the DMRS.

8. The method according to any one of claims 1 to 7, wherein the scheduling indication is transmitted in a DCI of a PDCCH located at a first mini-slot aggregation of slots.

9. The downlink data transmission method according to claim 8, wherein the DCI includes an indication, and the indication is an aggregated mini-slot number.

10. The downlink data transmission method according to claim 8, wherein the DCI includes an indication, and the indication is an aggregation mode in a time domain and/or a frequency domain.

11. The method according to any one of claims 1 to 7, wherein the mini-slots are aggregated according to a predefined aggregation pattern.

12. The downlink data transmission method according to claim 11, wherein the predefined aggregation mode is transmitted to the UE using higher layer signaling, particularly RRC signaling.

13. The downlink data transmission method according to claim 12, wherein the predefined aggregation mode is one of a plurality of predefined aggregation modes transmitted to the UE.

14. The method of claim 1, wherein the mini-slots are aggregated and scheduled to preempt a pre-scheduled transmission, and wherein the scheduling indication is transmitted on the PDCCH of the first OFDM symbol of the mini-slot aggregation.

15. The downlink data transmission method according to claim 14, wherein said mini-slot aggregation bearer URLLC service.

16. The method according to any one of claims 1 to 15, wherein each mini-slot in the mini-slot aggregation is located in the same slot.

17. The method according to any one of claims 1 to 16, wherein the mini-slot aggregation is located in a plurality of slots.

18. The method according to any one of claims 1 to 17, wherein the mini-slot aggregation is further aggregated into a mini-slot aggregation set.

19. The method of any one of claims 1 to 18, wherein mapping data comprises mapping transport blocks to mini-slot aggregations.