EP3959920A1

EP3959920A1 - Methods for communicating between a terminal and a base station, corresponding terminal, base station and computer program

Info

Publication number: EP3959920A1
Application number: EP20719201.4A
Authority: EP
Inventors: Hao Lin
Original assignee: Orange SA
Current assignee: Orange SA
Priority date: 2019-04-26
Filing date: 2020-04-20
Publication date: 2022-03-02
Also published as: FR3095565A1; US20220231799A1; WO2020216720A1

Abstract

The invention relates to a method for managing a communication between a base station and a terminal. According to the invention, the terminal being associated with at least one memory comprising at least two storage zones, the terminal implements: at least one step of storing (21), in one of the storage zones, a state representative of a transmission, by the base station, of at least one current data packet and control information related to the current data packet, referred to as a current transmission, the storage zone being identified by a storage zone indicator supported by the control information associated with the current data packet, the transmission (22) to the base station of all the states stored in the storage zones, when the terminal is authorized to transmit.

Description

DESCRIPTION

TITLE: Communication methods between a terminal and a base station, terminal, base station and corresponding computer program.

1. Field of the invention

The field of the invention is that of telecommunications.

More specifically, the invention relates to communications between a terminal and a base station, especially in unlicensed frequency bands.

The invention finds in particular, and not exclusively, applications in the field of 5G (in English NR for “New Radio”), for communications on unlicensed frequency bands (in English “NR-U” for “NR -based access to unlicensed spectrum ”).

2. Prior art

In order to increase the bandwidth and therefore the transmission rate in a communication network, the use of unlicensed frequency bands, that is to say, not allocated to a particular telephone operator or to a specific use, expands.

However, using these unlicensed frequency bands has some drawbacks. Indeed, since such frequency bands can be used by all mobile telephone operators, their accessibility is reduced and a certain lapse of time may elapse before a base station or a terminal can transmit data. .

In order to facilitate access to a channel in an unlicensed frequency band, access protocols have been proposed, such as the LBT access protocol (in English "Listen Before Talk", in French "listen before talk" ), and in particular its so-called “category 4” version.

According to this version, when a device wishes to transmit a signal in a channel belonging to an unlicensed frequency band, it first listens to the channel for a predetermined period (for example 34 ps). If the channel is busy, the sending equipment continues to listen to the channel, until the channel is detected as unoccupied or inactive ("idle").

For example, determining the occupation of a channel is based on an energy measurement. The transmitting equipment estimates the energy received on this channel and the compares to a predefined threshold. If the received energy exceeds this threshold, the channel is considered busy. Otherwise, it is considered unoccupied.

The transmitting equipment checks that the channel remains inactive for a predetermined time (eg 34 ps). Once this time has elapsed, the transmitting equipment draws a random value (in English "backoff") from a predefined range (for example an integer between 5 and 15), and checks for each counter value whether the channel remains unoccupied. , counting down from the value drawn.

For example, each counter value is associated with a 9 ps step. Thus, if the channel remains unoccupied for a period of 9 ps, the counter value is decremented by 1.

If during the countdown the channel is again occupied (in English "busy"), the sending equipment retains the current value of the counter and continues listening to the channel, until it detects that the channel is free again. The sending equipment checks again that the channel remains unoccupied for a predetermined time (eg 34 ps), then resumes counting from the last counter value.

When the count is complete (i.e. counter value equal to 0), the sending equipment can start transmitting data. The transmission time is called COT (in English "Channel Occupancy Time", in French "canal occupation time").

Depending on the LBT access protocol, communications can therefore be delayed while the channel is busy.

Furthermore, solutions have also been proposed for confirming the reception by a user equipment (UE) of data transmitted by a base station in the downlink. This technique is in particular known under the name “HARQ-ACK feedback” (“Hybrid Automatic Repeat reQuest - ACKnowledgment”).

For example, as described in the document “LTE; Physical layer procedures for shared spectrum channel access (3GPP TS 37.213 version 15.0.0 Release 15) ”, when a base station wishes to transmit data to user equipment, it notably transmits data on the PDSCH channel (“ Physical Downlink Shared Channel ”) and control information (DCI for“ Downlink Control Information ”).

The control information carries information relating to the reception of data, such as the time / frequency resource or the coding and modulation scheme. used to transmit the data. Such control information can also carry information relating to the time / frequency resource to be used by the user equipment to indicate whether the data has been decoded, also called the time / frequency resource for the “feedback”.

For example, the user equipment sends an ACK type message to the resource for feedback if the data packet is correctly decoded, or a NACK type message otherwise.

Since the base station allocates the time / frequency resource to be used by the UE for feedback, the base station can read the message it receives on this resource to verify if the UE has decoded the data.

If the base station receives an ACK type message associated with a current data packet, it can consider that the current data packet has been correctly received.

If the base station receives a NACK type message associated with a current data packet, it can retransmit the current data packet, possibly with different redundancy data (RV or “Redundancy values”). In this way, the UE can reconstruct the current data packet using the initial transmission and re-transmission.

On the other hand, if the base station does not receive any message on the time / frequency resource allocated for the feedback, the base station considers that the communication has been interrupted (DTX for “Discontinuous transmission”). The base station assumes that the UE has not received the DCI control information, therefore has not been aware of the transmission of a data packet and has not attempted to decode it. The base station then decides to transmit the DCI control information again with a different coding, as well as to retransmit the data packet on the PDSCH channel, possibly with a different modulation and coding scheme.

However, as noted above for communications on unlicensed frequency bands (eg NR-U), depending on the LBT access protocol, some communications may be delayed as long as the channel is busy.

Thus, transmission by the user equipment of a message to indicate whether the data packet has been decoded can be delayed as long as the channel is busy. In particular, user equipment may have decoded a data packet, and wish to transmit an ACK type message on the resource allocated for feedback. In order to be able to transmit the ACK message in an unlicensed frequency band, the user equipment runs the LBT access protocol. As long as the channel is busy, transmission of the ACK message is prohibited. The base station, not receiving any message on the time / frequency resource allocated for feedback, will consider that the communication has been interrupted (DTX). The base station will transmit the DCI control information and the data packet again, resulting in loss of spectral efficiency.

There is therefore a need for a technique making it possible to manage communications between user equipment, also called a terminal, and a base station, in particular in unlicensed frequency bands, which does not have all or part of the drawbacks of the prior art. .

3. Disclosure of the invention

The invention provides, according to one embodiment, a method of managing a communication between a base station and a terminal. In particular, such a method is implemented at the level of a terminal.

According to this embodiment, the terminal is associated with at least one memory comprising at least two storage areas, and implements:

at least one step of storing, in one of the storage areas, a state representative of a transmission, by the base station, of at least one current data packet and control information associated with the data packet current, called current transmission, said storage area being identified by a storage area indicator carried by the control information associated with the current data packet, the transmission, to the base station, of all the states stored in the storage areas, when said terminal is authorized to transmit.

For example, the representative state of a transmission belongs to the group comprising:

the data packet has been decoded (for example of ACK type);

the data packet has not been decoded (for example of NACK type);

control information has not been received (eg DTX type).

The proposed solution thus makes it possible to keep in memory the states representative of the transmissions of data packets from the base station to the terminal, as long as the terminal is not authorized to transmit. In particular, the proposed solution makes it possible to improve the “HARQ-ACK feedback” technique.

When the terminal is authorized to transmit, for example when the channel is considered unoccupied following the progress of the LBT access protocol, the terminal transmits to the base station the history of states representative of the transmissions. In this way, the base station receives information about previous transmissions, and can decide whether it is desirable to retransmit certain data packets (especially data packets associated with a NACK or DTX state).

This optimizes the spectral efficiency of communications by avoiding the systematic retransmission of data packets for which the base station has not received a message from the terminal indicating whether the data has been decoded.

In particular, for a current transmission, if the base station has not received a message indicating whether the data has been decoded on a time / frequency resource allocated for feedback, the base station can determine, during a following transmission:

if the terminal has not actually received the control information for the current transmission (and return the control information with possibly a suitable coding rate and the current data packet with a suitable coding and modulation scheme), or

if the terminal received control information for the current transmission but could not send a message indicating whether the data was decoded because the channel was busy.

In particular, the proposed solution is well suited to communications on unlicensed frequency bands (NR-U).

According to a particular embodiment, the method also implements at least one step of storing, in one of the storage areas, a state representative of a transmission, by the base station, of at least one packet of data. previous data and control information associated with the previous data packet, referred to as the previous transmission, said storage area being identified from the storage area indicator carried by the control information associated with the current data packet.

According to this embodiment, the storage of a state representative of a current transmission can be used to determine the state representative of a previous transmission. For example, the storage areas of a memory are organized in a stack, and the method implements:

identification, from the storage area indicator carried by the control information associated with the current data packet, of a storage area of a state representative of the current transmission, corresponding to a current level in the stack, the determination, from the control information associated with the current data packet, that the control information associated with the previous data packet has not been received,

storing in at least one empty storage area corresponding to a level lower than the current level in the stack, of a state representative of the previous transmission indicating that the control information associated with the previous data packet has not been received.

According to a particular embodiment of the invention, the method implements: the detection, in the control information associated with the current data packet, of a reception indicator indicating that the base station has received all of the states representative of previous transmissions, stored in storage areas;

refreshing the storage areas before storage of the state representative of the current transmission.

According to this embodiment, a new indicator is proposed, denoted for example NAI (“New Ack Indication”), making it possible to inform the terminal that the base station has received all of the states representative of the previous transmissions and that it It is therefore possible to delete these states from the storage areas.

According to a particular embodiment, the terminal is associated with at least two memories.

When several memories are used, the storage area can be identified by a storage area indicator (denoted for example SetlD) and by a memory indicator (denoted for example AckJD). The different memories can have a different number of storage areas.

In particular, each memory can be associated with a different level of quality of service.

In another embodiment, the invention relates to a terminal capable of communicating with a base station, comprising at least one memory comprising at least two storage areas, and at least one processing unit configured for: - store, in one of the storage areas, at least one state representative of a transmission, by the base station, of at least one current data packet and control information associated with the current data packet, called transmission current, said storage area being identified by a storage area indicator carried by the control information associated with the current data packet,

- transmit, to the base station, all the states stored in the storage areas.

In particular, the processing unit is configured to store states representative of successive transmissions, and to transmit all of these states when the terminal is authorized to transmit.

For example, the processing unit is a processor operably coupled to the memory or memories associated with the terminal.

Such a terminal is particularly suitable for implementing the method of managing a communication described above. This is, for example, user equipment such as a cell phone. This terminal could of course include the various characteristics relating to the method according to the invention, which can be combined or taken in isolation. Thus, the characteristics and advantages of this terminal are the same as those of the method described above. Therefore, they are not detailed further.

The invention also relates, according to one embodiment, to a method of communication between a base station and a terminal. In particular, such a method is implemented at the level of a base station.

According to this embodiment, the terminal being associated with at least one memory comprising at least two storage areas, the base station implements:

at least one step of transmitting to the terminal at least one current data packet and control information associated with the current data packet, called current transmission, the control information bearing a storage area indicator identifying a storage area a state representative of the current transmission, among the storage areas,

the reception of all the states representative of the transmissions, stored in the storage areas.

Thus, according to this embodiment, the base station knows, for each transmission, in which storage area the state of the transmission can be stored. As already indicated, the proposed solution thus makes it possible to keep in memory the states representative of the transmissions of data packets from the base station to the terminal, as long as the terminal is not authorized to transmit. When the terminal is authorized to transmit, the base station receives the states representative of previous transmissions, and can decide whether it is desirable to retransmit certain data packets.

According to a particular embodiment, the control information also carries at least one piece of information belonging to the group comprising:

a memory indicator (denoted for example AckJD) identifying a memory from among said at least one memory associated with the terminal;

a reception indicator (denoted for example NAI) indicating that the base station has received all of the stored states representative of the transmissions;

at least one time / frequency resource intended to be used by the terminal to transmit to the base station all the states representative of the transmissions (time / frequency resource allocated for feedback).

In particular, the reception indicator changes state upon receipt of all the states representative of transmissions, and is transmitted in the control information of a subsequent transmission.

In this way, the terminal can detect that the base station has received the states representative of the previous transmissions, and refresh the memory or memories associated with it.

According to a particular embodiment, the memory is organized in a stack, and the control information associated with the first data packet carries a storage area indicator identifying the storage area corresponding to the first level of the stack, and the control information associated with the following data packets respectively bear a storage area indicator identifying the storage area corresponding to the directly higher level.

This way, it is easier to detect transmission failures when a stack storage area is empty.

According to a particular embodiment, the method implements:

identification of transmission failures, based on all the states representative of the received transmissions; retransmission of data packets and control information associated with transmission failures.

According to a particular characteristic, when all the storage areas of a memory among said at least one memory associated with the terminal are used, and the states representative of the transmissions have not been received, the method implements a retransmission of the 'set of data packets and control information associated with these data packets.

In this way, it is ensured that the data packets will actually be received by the terminal.

In another embodiment, the invention relates to a base station capable of communicating with a terminal associated with at least one memory comprising at least two storage areas, said base station comprising at least one processing unit configured for:

transmit to the terminal at least one current data packet and control information associated with the current data packet, called current transmission, said control information bearing a storage area indicator identifying a storage area of a state representative of the transmission current, among the storage areas,

receive all the representative states of the transmissions, stored in the storage areas.

In particular, the processing unit is configured to transmit data packets and control information, and to receive all of the states representative of the transmissions when the terminal is authorized to transmit.

For example, the processing unit is a processor operably coupled to a memory of the base station.

Such a base station is particularly suitable for implementing the communication method described above. This is for example an eNodeB. The base station could of course include the various characteristics relating to the method according to the invention, which can be combined or taken in isolation. Thus, the characteristics and advantages of the base station are the same as those of the method described above. Therefore, they are not detailed further.

The invention also relates to one or more computer programs comprising instructions for the implementation of at least one method as described above. when this or these programs are executed by at least one processor.

The invention also relates to an information medium readable by a computer, and comprising instructions of a computer program as mentioned above.

4. List of figures

Other characteristics and advantages of the invention will emerge more clearly on reading the following description of a particular embodiment, given by way of simple illustrative and non-limiting example, and the accompanying drawings, among which:

[Fig 1] Figure 1 illustrates the main steps implemented by a base station according to one embodiment of the invention;

[Fig 2] Figure 2 illustrates the main steps implemented by a terminal according to one embodiment of the invention;

[Fig 3] Figure 3 illustrates the structure of different memories associated with a terminal according to one embodiment of the invention;

[Fig 4A]

[Fig 4B]

[Fig 4C]

[Fig 4D] Figures 4A to 4D illustrate a first example of communication between a base station and a terminal according to an embodiment of the invention;

[Fig 5A]

[Fig 5B]

[Fig 5C]

[Fig 5D]

[Fig 5E] Figures 5A to 5E illustrate a second example of communication between a base station and a terminal according to an embodiment of the invention;

[Fig 6A]

[Fig 6B]

[Fig 6C]

[Fig 6D] Figures 6A to 6D illustrate a third example of communication between a base station and a terminal according to an embodiment of the invention;

[Fig 7] Figure 7 shows the simplified structure of a terminal implementing a communication management method according to one embodiment of the invention;

[Fig 8] FIG. 8 presents the simplified structure of a base station implementing a communication method according to an embodiment of the invention. 5. Description of an embodiment of the invention

5.1 General principle

The general principle of the invention is based on the transmission of data packets and control information associated with these data packets in downlink, ie from a base station to a terminal, and storage in storage areas. a memory associated with the terminal, identified by the base station, a state representative of each transmission.

It is thus possible for the terminal to transmit to the base station all the states representative of the transmissions, when it is authorized to transmit.

In this way, upon receipt of all the states representative of the transmissions, the base station can determine whether there has indeed been one or more transmission failures, in which case it is necessary to retransmit the corresponding data packet and the corresponding data packet. associated control information.

Compared to prior art techniques, the base station does not assume that communication has been interrupted in the absence of a message on a time / frequency resource allocated for feedback. The base station determines that the communication has been terminated only upon receipt of a state representative of the transmission such as transmission failure, such as DTX.

According to a particular embodiment, the terminal transmits to the base station all the states stored in the storage areas when it is authorized to transmit on a time / frequency resource identified from the control information, the control information. control carrying information relating to at least one time / frequency resource intended to be used by the terminal to transmit to the base station all the states representative of the transmissions.

In particular, this information relating to at least one time / frequency resource for the feedback can be common to the control information associated with different data packets. In other words, the control information associated with different data packets identifies one (or more) same time / frequency resource to be used by the terminal for feedback.

Considered below is a communication network implementing at least one base station and at least one terminal. For example, the communication network is a cellular network. In relation to FIGS. 1 and 2, the main steps implemented by a terminal and a base station of the communication network according to one embodiment of the invention are presented.

It is considered that the terminal is associated with at least one memory. Such a memory can therefore be an internal component of the terminal, or an external component belonging to another item of equipment in communication with the terminal, such as a remote server. The address of such a memory can in particular be defined by a memory indicator, denoted for example AckJD. Such a memory comprises at least two storage areas. The address of each storage area can be defined by a storage area indicator, denoted for example SetlD. In particular, the memory is a stack memory, and each storage area corresponds to a segment of the stack.

According to the embodiment illustrated in Figure 1, the base station implements at least one step 11 of transmitting at least one data packet and control information associated with the data packet. Current transmission is the transmission of a current data packet from the base station to the terminal, for example on a PDSCH type channel, and of control information associated with the current data packet, for example of DCI type. Several transmission steps can be implemented to successively transmit the various data packets and associated control information.

According to this embodiment, the control information carries a storage area indicator identifying a storage area of a state representative of the current transmission, among the storage areas of the memory associated with the terminal.

Thus, for each transmission of a new data packet, a different storage area can be allocated by the base station.

As illustrated in FIG. 2, the terminal implements, for its part, at least one step 21 of storing a state representative of a current transmission, ie of the transmission by the base station of at least one packet of current data (for example on a PDSCH type channel) and control information (for example of DCI type) associated with the current data packet. According to this embodiment, the storage area is identified by the storage area indicator carried by the control information associated with the current data packet. It is noted that, in certain cases, the reception of a current data packet and associated control information makes it possible to store, in one of the storage areas, a state representative of a previous transmission.

When the terminal is authorized to transmit, it implements a transmission 22, to the base station, of all the states S stored in the storage areas of at least one memory.

The base station, for its part, implements a step of receiving 12 of all the states S representative of the transmissions.

An example of the implementation of the invention is described below, for communication between a base station and a terminal on unlicensed frequency bands (eg NR-U).

As illustrated in FIG. 3, it is considered that the terminal is associated with one or more memories, identified by a memory indicator AckJD. When only one memory is associated with the terminal, such a memory flag is optional. Each memory is divided into several segments, corresponding to different storage areas. Each storage area is identified by a SetJD storage area indicator. The number of storage areas in each memory may be different. The AckJD memory can be considered as a buffer memory making it possible to store the representative state of transmissions with an identifier (for example ACK if the data packet has been decoded, NACK if the data packet has not been decoded, or DTX if control information has not been received). The storage area indicator can be thought of as a pointer to the buffer.

According to the embodiment described below, a reception indicator N Al is introduced, indicating that the base station has received all of the stored states representative of previous transmissions.

When the base station transmits control information (for example of DCI type) and a corresponding data packet (for example on the PDSCH channel), the control information carries the storage area indicator and possibly the memory indicators. and / or reception.

According to the embodiment, the control information also makes it possible to identify one or more time / frequency resource for the feedback, intended to be used (s) by the terminal to transmit to the base station all the data. representative states of transmissions. For example, the reception indicator NAI is a binary value (0 or 1) which indicates whether all of the states representative of the transmissions, stored in the memory AckJD, have been received by the base station. For a current transmission, identifying an AckJD memory, if the value of the reception indicator is modified compared to the previous transmission identifying the same AckJD memory, this means that the base station has received all the states representative of the transmissions, stored in AckJD memory. Otherwise, it means that the base station has not yet received the representative states, stored in the memory AckJD.

By way of illustration, in relation to FIGS. 4A to 4D, a first example of communication between a base station and a terminal is presented according to one embodiment of the invention. For the first data transmission from the base station to the terminal, the base station identifies at least one memory associated with the terminal, for example a single memory identified by the indicator AckJD = 0, a storage area, for example set = 0, and a default value for the reception indicator, for example NAI = 0. For example, the memory AckJD = 0 includes five storage areas organized in a stack, denoted set 0, set 1, set 2, set 3 and set 4.

As illustrated in FIG. 4A, for the transmission of the DCI control information and of the first data packet on the PDSCH channel, called the first transmission, the control information carries the parameters (AckJD = 0, set = 0, NAI = 0).

If the terminal receives the DCI control information, it can store the state of the first transmission in the storage area identified in the control information. For example, the terminal has received and decoded the first data packet. It therefore stores the ACK value in the storage area set = 0 of the memory AckJD = 0.

If the terminal is authorized to transmit, it can transmit to the base station all the states representative of the transmissions. For the first transmission, only one state is stored in the storage area set = 0, so only one result can be transmitted to the base station if the terminal is authorized to transmit.

Note that the storage and transmission steps can be implemented simultaneously or successively.

It is assumed that the terminal is not authorized to send (failure of the LBT access protocol for example). It cannot therefore transmit its status (“ACK”) - for example on the time / frequency resource allocated for feedback. As illustrated in FIG. 4B, the base station schedules the transmission of a second data packet on the PDSCH channel and the associated DCI control information, called the second transmission.

In particular, if the memory is organized in a stack, the control information associated with the first data packet carries a storage area indicator identifying the storage area corresponding to the first level of the stack (set = 0), and the storage area information. control associated with the following data packets respectively bear a storage area indicator identifying the storage area corresponding to the directly higher level.

The control information associated with the second data packet then carries the parameters (AckJD = 0, set = 1, N Al = 0).

If the terminal does not receive the DCI control information, it does not know that a second data packet has been transmitted. It therefore does not store any information in the AckJD memory. The base station does not receive any information on the time / frequency resource allocated for feedback.

Note that if the terminal had received the DCI control information, it would have stored the state of the second transmission in the set = 1 storage area identified in the control information. In addition, the terminal could have read the value of the NAI reception flag and deduced that, since this value is identical to the value carried by the control information received during the previous transmission for the same memory, this means that the base station has not received the representative states of previous transmissions. The terminal would therefore have stored the state of the second transmission in the storage area identified in the control information, set = 1, and attempted to transmit all the states representative of the transmissions.

As illustrated in Figure 4C, the base station schedules the transmission of a third data packet on the PDSCH channel and associated DCI control information, called a third transmission. The control information then carries the parameters (AckJD = 0, set = 2, NAI = 0).

If the terminal receives the DCI control information, it can store the state of the third transmission in the set = 2 storage area identified in the control information. For example, the terminal did not correctly decode the PDSCH channel carrying the third data packet. It therefore stores the value NACK in the storage area set = 2 of the memory AckJD = 0.

In particular, especially if the memory is organized in a stack, the terminal can detect that at least one storage area of a lower level than the current storage area of the third data packet is empty, which means that the information of checks of a previous transmission (ie the second transmission) were not received.

In the example illustrated in FIG. 4C, the terminal therefore stores in the empty storage area set = 1 (corresponding to a level directly lower than the current level set = 2 of the stack) a state representative of the previous transmission indicating that the information checks associated with the previous data packet were not received. For example, the DTX value is stored in the storage area set = 1 which was left empty.

If the terminal is authorized to transmit, it can transmit to the base station all the states representative of the transmissions. For the third transmission, three states are stored in the storage area set = 0 (AC K), set = 1 (DTX) and set = 2 (NACK), so three results can be transmitted to the base station if the terminal is authorized to transmit. For example, these states are transmitted on one of the time / frequency resources allocated by the base station for feedback.

More generally, the terminal transmits all the stored states of the storage area identified by the initial storage area indicator (set = 0) to the storage area indicator of the last transmission identified in the control information. of the current transmission (set = 2).

As illustrated in FIG. 4C, it is assumed that the terminal is finally authorized to transmit, for example following the successful execution of the LBT access protocol. The base station therefore receives all the states stored in the memory AckJD = 0, transmitted for example on one of the time / frequency resources allocated by the base station for the feedback.

As illustrated in FIG. 4D, following the reception of all the states stored in the memory AckJD = 0 by the base station, the value of the indicator N Al goes from 0 to 1, and the base station programs it. transmission of a fourth data packet on the PDSCH channel and the associated DCI control information, called the fourth transmission. The reception indicator therefore changes state on reception of all representative states of transmissions, and may be transmitted in the control information of a subsequent transmission.

As the states stored in the memory AckJD = 0 have been received by the base station, it is possible to refresh the memory AckJD and start recording again the states representative of the transmissions. The control information then carries the parameters (AckJD = 0, set = 0, N Al = 1).

In the example illustrated in Figure 4D, it is assumed that the terminal receives the DCI control information. It detects in the control information associated with the current data packet (fourth data packet) a change of state of the reception indicator NAI (NAI = 1), indicating that the base station has received all the states. representative of previous transmissions.

The terminal empties ("flush") all the storage areas of the AckJD = 0 memory, before storing the state representative of the current transmission (i.e. fourth transmission).

The terminal can then store the state of the fourth transmission in the set = 0 storage area identified in the control information. For example, the terminal has decoded the PDSCH channel carrying the fourth data packet. It therefore stores the ACK value in the storage area set = 0 of the memory AckJD = 0.

With reference to FIGS. 5A to 5E, a second example of communication between a base station and a terminal according to an embodiment of the invention is now presented.

Figures 5A to 5C are identical to Figures 4A to 4C and are therefore not described in more detail.

As illustrated in FIG. 5C, at the end of the third transmission, three states are stored in the memory AckJD = 0: ACK in the storage area set = 0, DTX in the storage area set = 1, and NACK in the storage area. storage area set = 2. The terminal can transmit all states stored in the memory AckJD = 0 when it is authorized to transmit.

As illustrated in FIG. 5D, following the reception of all the states stored in the memory AckJD = 0 by the base station, the value of the NAI indicator goes from 0 to 1, and the base station programs the transmission. a fourth data packet on the PDSCH channel and associated DCI control information, called a fourth transmission. As already indicated in relation to FIG. 4D, it is possible to refresh the memory AckJD and start recording again the states representative of the transmissions since the states stored in the memory AckJD = 0 have been received by the base station. The control information then carries the parameters (AckJD = 0, set = 0, N Al = 1).

In the example illustrated in Figure 5D, it is assumed that the terminal does not receive the DCI control information. The terminal therefore does not know that a fourth data packet has been sent. It does not store any information in AckJD memory, and the base station does not receive any information about the time / frequency resource allocated for feedback.

As illustrated in FIG. 5E, the base station schedules the transmission of a fifth data packet on the PDSCH channel and associated DCI control information, called a fifth transmission. The control information then carries the parameters (AckJD = 0, set = 1, N Al = 1).

The terminal detects in the control information associated with the current data packet (fifth data packet) a change of state of the reception indicator N Al (N Al = 1) with respect to the last control information received (third transmission ), indicating that the base station has received all of the states representative of previous transmissions.

The terminal empties ("flush") all the storage areas of the memory AckJD = 0, before storing the state representative of the current transmission (i.e. fifth transmission).

If the terminal receives the DCI control information, it can store the status of the fifth transmission in the set = 1 storage area identified in the control information. For example, the terminal has decoded the PDSCH channel carrying the fifth data packet. It therefore stores the ACK value in the storage area set = 1 of the memory AckJD = 0.

In particular, especially if the memory is organized in a stack, the terminal can detect that at least one storage area of a lower level than the storage area of the fifth data packet is empty, which means that the control information of the previous transmission (ie the fourth transmission) were not received.

In the example illustrated in FIG. 5E, the terminal stores in the empty storage area set = 0 a state representative of the previous transmission (ie the fourth transmission) indicating that the control information associated with the previous data packet has not been received. For example, the DTX value is stored in the storage area set = 0.

If the terminal is authorized to transmit, it can transmit to the base station all the states representative of the transmissions. For the fifth transmission, two states are stored in the storage areas set = 0 (DTX) and set = 1 (ACK), so two results can be transmitted to the base station. For example, these states are transmitted on one of the time / frequency resources allocated by the base station for feedback.

According to the examples illustrated, the base station can therefore detect, from the control information of a current transmission, a transmission failure of a previous transmission (i.e. when the terminal does not receive the control information).

In the event of a transmission failure (for example DTX state associated with a transmission), the base station can retransmit the corresponding data packets and the associated control information, possibly by adapting the coding rate and / or the modulation scheme. and coding.

It can be noted that when all the storage areas of a memory are used, and the states representative of the transmissions have not been received, the base station implements a retransmission of all the corresponding data packets and control information associated with these data packets. It is then possible to empty the memory.

In the two communication examples described above, it was considered that a single memory was associated with a terminal. According to other examples, several memories can be associated with a terminal. In this case, the different memories can be used for different services having different quality of service (QoS) levels.

For example, it is considered that the user of the terminal has subscribed to two different services: a first service of the download type, tolerating a certain latency, and a second service of the mobile telephone type, requiring low latency.

Considering the use of a single memory, the states representative of the transmissions associated with the first service and the second service, stored in the single memory, are mixed. The base station which receives all the states can it is therefore difficult to control the quality of service and the spectral efficiency of these two services. In particular, if the latency is to be low, the base station may decide not to wait to receive all of the states and assume, after a predetermined time, that all transmissions have failed (DTX). However, in this case, as the first service can withstand greater latency than the second service, the base station could have waited longer to receive the states representative of the transmissions associated with the first service, before assuming that all the transmissions had failed. .

Considering the use of two memories, one per service, it is possible to optimize the spectral efficiency. Indeed, as the base station can wait longer for the reception of the states representative of the transmissions associated with the first service (supporting a higher latency), it does not systematically consider a failure of the transmissions associated with the first service, and therefore does not retransmit necessarily the data packets associated with this first service.

FIGS. 6A to 6D illustrate a third example of communication between a base station and a terminal according to an embodiment of the invention, implementing two memories associated with a terminal, denoted for example AckJD = 0 and AckJD = 1. The memory AckJD = 0 is associated with a first service tolerating a certain latency (service 1), and the memory AckJD = 1 is associated with a second service requiring a low latency (service 2).

As illustrated in FIG. 6A, for the transmission of a first data packet on the PDSCH channel associated with the first service and the associated DCI control information, the control information carries the parameters (AckJD = 0, set = 0, N Al = 0).

For example, the terminal has received and decoded the first data packet associated with the first service. It therefore stores the ACK value in the storage area set = 0 of the memory AckJD = 0.

It is assumed that the terminal is not authorized to transmit (failure of the LBT access protocol for example). It cannot therefore transmit its state (“ACK”) to the base station.

As illustrated in FIG. 6B, for the transmission of a first data packet on the PDSCH channel associated with the second service and DCI control information y associated, the control information carries the parameters (AckJD = 1, set = 0, NAI = 0).

For example, the terminal has received and decoded the first data packet associated with the second service. It therefore stores the ACK value in the storage area set = 0 of the memory AckJD = 1.

It is assumed that the terminal is still not authorized to transmit.

As illustrated in Figure 6C, for the transmission of a second data packet associated with the second service and associated DCI control information, the control information carries the parameters (AckJD = 1, set = 1, NAI = 0).

For example, the terminal has received and decoded the second data packet associated with the second service. It therefore stores the ACK value in the set = 1 storage area of the AckJD = 1 memory.

It is assumed that the terminal is still not authorized to transmit.

Since the second service is associated with low latency, the base station may decide not to wait to receive all the states and assume, after a predetermined time, that all transmissions associated with the second service have failed (DTX), and scheduling a re-transmission of the corresponding data packets.

As illustrated in FIG. 6D, following this decision, the value of the NAI indicator changes from 0 to 1, and the base station schedules the re-transmission of the first data packet associated with the second service and the associated DCI control information. .

As the base station will retransmit the data packets associated with transmission failures, it is possible to refresh the memory AckJD = 1 and to resume recording the states representative of the transmissions associated with the second service. The control information then carries the parameters (AckJD = 1, set = 0, NAI = 1).

In particular, the memory associated with the low latency service may have a size, i.e. a number of storage areas, smaller than that of the memory associated with the service tolerating a higher latency.

Thus, when all the storage areas of a memory associated with the low latency service are used, and the states representative of the transmissions have not been received by the base station, the base station implements a retransmission of the set of corresponding data packets associated with the low latency service and associated control information.

More generally, it can be noted that the greater the number of storage areas in a memory associated with a terminal, the more the terminal can store states representative of the transmissions, and the longer the base station can wait before receiving the message. set of states. This optimizes the spectral efficiency. When the last memory storage area is full, and the base station still has not received all of the representative transmission states, it means that the load is high, i.e. the channel is heavily occupied. In this case, the base station assumes that all previous transmissions, corresponding to states stored in memory, have failed (DTX).

It is desirable to properly size the memories, taking particular account of the latency tolerated for the service considered. For example, a memory comprising four or five storage areas can be used.

Furthermore, in order to reduce the transmission latency of all the states representative of transmissions from the terminal to the base station, the base station can identify, in the control information, several time / frequency resources for the feedback. For example, the base station can allocate two time / frequency resources for a current transmission so that the terminal can report the status of the transmission. The terminal can then run the LBT access protocol on a first resource. If successful, the terminal can transmit the transmission status to this first resource. If this fails, the terminal can roll out the LBT access protocol on the second resource. This optimizes the probability of success of the LBT access protocol.

Finally, with reference to Figures 7 and 8, the simplified structures of a terminal and a base station according to at least one embodiment described above are presented.

As illustrated in FIG. 7, a terminal comprises at least one memory 71 comprising a buffer memory comprising at least two storage areas, at least one processing unit 72, equipped for example with a programmable computing machine or with a control machine. dedicated calculation, for example a processor P, and controlled by the computer program 73, implementing steps of the method for managing a communication according to at least one embodiment of the invention. On initialization, the code instructions of the computer program 73 are for example loaded into a RAM memory before being executed by the processor of the processing unit 72.

The processor of the processing unit 72 implements steps of the method of managing a communication described above, according to the instructions of the computer program 73, to:

store, in one of the storage areas, at least one state representative of a transmission, by the base station, of at least one current data packet and control information associated with the current data packet, called current transmission , said storage area being identified by a storage area indicator carried by the control information associated with the current data packet,

transmit, to the base station, all the states stored in the storage areas.

As illustrated in FIG. 8, such a base station comprises at least one memory 81 comprising a buffer memory, at least one processing unit 82, equipped for example with a programmable computing machine or with a dedicated computing machine, for example. example a processor P, and controlled by the computer program 83, implementing steps of the communication method according to at least one embodiment of the invention.

On initialization, the code instructions of the computer program 83 are for example loaded into a RAM memory before being executed by the processor of the processing unit 82.

The processor of the processing unit 82 implements steps of the communication method described above, according to the instructions of the computer program 83, to:

transmit to a terminal at least one current data packet and control information associated with the current data packet, called current transmission, the control information bearing a storage area indicator identifying a storage area of a state representative of the current transmission, among the storage areas of a memory associated with the terminal,

Claims

1. A method of managing a communication between a base station and a terminal, characterized in that, said terminal being associated with at least one memory comprising at least two storage areas, said terminal implements:

at least one step of storing (21), in one of said storage areas, a state representative of a transmission, by the base station, of at least one current data packet and control information associated with said current data packet, called current transmission, said storage area being identified by a storage area indicator carried by said control information associated with said current data packet,

transmitting (22), to said base station, all of the states stored in said storage areas, when the transmission channel between said terminal and said base station is considered unoccupied.

2. Method according to claim 1, characterized in that it also implements at least one step of storing, in one of said storage areas, a state representative of a transmission, by the base station, of at least one previous data packet and control information associated with said previous data packet, called previous transmission, said storage area being identified from the storage area indicator carried by said control information associated with said data packet current data.

3. Method according to claim 2, characterized in that said storage areas of a memory are organized in a stack, and in that said method implements:

the identification, from the storage area indicator carried by said control information associated with the current data packet, of a storage area of a state representative of the current transmission, corresponding to a current level in said battery,

determining, from said control information associated with the current data packet, that the control information associated with the previous data packet has not been received,

the storage in at least one empty storage area corresponding to a level lower than said current level in the stack, of a state representative of the transmission previous indicating that the control information associated with the previous data packet was not received.

4. Method according to any one of claims 1 to 3, characterized in that it implements:

detecting, in said control information associated with the current data packet, a reception indicator indicating that the base station has received all of the states representative of previous transmissions, stored in said storage areas;

refreshing said storage areas before storing the state representative of the current transmission.

5. Method according to any one of claims 1 to 4, characterized in that said terminal is associated with at least two memories, each memory being associated with a different level of quality of service.

6. Method according to any one of claims 1 to 5, characterized in that said state representative of a transmission belongs to the group comprising:

the data packet has been decoded;

the data packet has not been decoded;

control information has not been received.

7. Method of communication between a base station and a terminal, characterized in that, said terminal being associated with at least one memory comprising at least two storage areas, said base station implements:

at least one step of transmitting (11) to said terminal at least one current data packet and control information associated with said current data packet, called current transmission, said control information bearing a storage area indicator identifying a storage area of a state representative of the current transmission, among said storage areas,

receiving (12) all of the states representative of transmissions, stored in said storage areas, when the transmission channel between said terminal and said base station is considered unoccupied.

8. A communication method according to claim 7, characterized in that said control information also carries at least one item of information belonging to the group comprising:

a memory indicator identifying a memory among said at least one memory associated with the terminal;

a reception indicator indicating that the base station has received all of the stored states representative of the transmissions;

at least one time / frequency resource intended to be used by said terminal to transmit to the base station all the states representative of the transmissions.

9. A communication method according to claim 8, characterized in that said reception indicator changes state upon receipt of all the states representative of the transmissions, and is transmitted in the control information of a following transmission.

10. The communication method according to any one of claims 7 to 9, characterized in that, said memory being organized in a stack, the control information associated with the first data packet carries a storage area indicator identifying the storage area. corresponding to the first level of the stack, and the control information associated with the following data packets respectively bear a storage area indicator identifying the storage area corresponding to the directly higher level.

11. A communication method according to any one of claims 7 to 10, characterized in that it implements:

the identification of transmission failures, based on all the states representative of the received transmissions;

retransmission of data packets and control information associated with transmission failures.

12. A communication method according to any one of claims 7 to 1 1, characterized in that when all the storage areas of a memory among said at least one memory associated with the terminal are used, and that the states representative of the transmissions have not been received, said method implements a retransmission of all the data packets and the control information associated with these data packets.

13. Terminal capable of communicating with a base station, characterized in that said terminal comprises at least one memory comprising at least two storage areas, and at least one processing unit configured for:

store, in one of said storage areas, at least one representative state a transmission, by the base station, of at least one current data packet and control information associated with said current data packet, called current transmission, said storage area being identified by a storage area indicator carried by said control information associated with said current data packet, transmitting, to said base station, all of the states stored in said storage areas, when the transmission channel between said terminal and said base station is considered unoccupied .

14. Base station capable of communicating with a terminal associated with at least one memory comprising at least two storage areas,

characterized in that said base station comprises at least one processing unit configured for:

transmit to the terminal at least one current data packet and control information associated with said current data packet, called current transmission, said control information bearing a storage area indicator identifying a storage area of a state representative of the transmission current, among said storage areas,

receive all the states representative of the transmissions, stored in said storage areas, when the transmission channel between said terminal and said base station is considered unoccupied.

15. A computer program comprising instructions for implementing a method according to claim 1 when this program is executed by a processor.