WO2024013810A1

WO2024013810A1 - Wireless communication system, wireless communication method, and wireless communication device

Info

Publication number: WO2024013810A1
Application number: PCT/JP2022/027281
Authority: WO
Inventors: 花絵大谷; 裕介淺井; ヒランタアベセカラ; 朗岸田; 純一岩谷; 信也大槻; 陸大宮; 泰司鷹取
Original assignee: 日本電信電話株式会社
Priority date: 2022-07-11
Filing date: 2022-07-11
Publication date: 2024-01-18

Abstract

The present disclosure relates to a wireless communication system, a wireless communication method, and a wireless communication device. The wireless communication system according to the present disclosure comprises a base station having multilink function, and a terminal having multilink function, and is configured to perform communication between the base station and the terminal through a plurality of links. The base station comprises an upper MAC for receiving a packet generated in an upper layer and lower MACs each of which is present in a corresponding one of the plurality of links, and is configured to execute: a dummy packet transmission process for transmitting a dummy packet from the upper MAC to the respective lower MACs; a process for replacing a high-priority packet having a high priority level with the dummy packet; and a process for transmitting the packet held in each of the lower MACs to the terminal through the links.

Description

Wireless communication system, wireless communication method, and wireless communication device

The present disclosure relates to a wireless communication system, a wireless communication method, and a wireless communication device.

Wireless LAN base stations and terminals use CSMA/CA to access channels and transmit data.

IEEE 802.11be, a wireless LAN communication standard, is equipped with a multi-link function that allows multiple frequency bands to be used together. By using the multilink function, multiple links using multiple frequency bands can be simultaneously formed between a base station and a terminal. This improves throughput and delay characteristics by simultaneously transmitting different data in multiple frequency bands.

When transmitting data, packets generated in the upper layer are first passed to the Upper MAC (Media Access Controller). The Upper MAC passes packets to the Lower MAC that exists for each link. When the Lower MAC acquires the right to transmit a frame, the packet that comes to the forefront in the order of held packets is passed to the physical layer (PHY), and then transmitted.

However, when performing large-capacity communication, the Lower MACs of all links used in the multilink function may already have multiple transmission packets. In this case, it is assumed that a high-priority packet is generated, which is a transmission packet of an application that requires low delay. This high-priority packet cannot be immediately passed to the PHY and transmitted using any link. That is, there was a problem in that queuing delays occurred.

In order to solve the above-mentioned problems, the first object of the present disclosure is to provide a wireless communication system that can shorten the queuing delay of high-priority packets.

A second objective of the present disclosure is to provide a wireless communication method that can shorten the queuing delay of high-priority packets.

A third objective of the present disclosure is to provide a wireless communication device that can shorten the queuing delay of high-priority packets.

A first aspect of the present disclosure is a wireless communication system that includes a base station with a multilink function and a terminal with the multilink function, and is configured such that the base station and the terminal communicate via multiple links. The base station includes an Upper MAC that receives packets generated in the upper layer and a Lower MAC that exists for each link, and performs a dummy packet transmission process that transmits a dummy packet from the Upper MAC to the Lower MAC. , a wireless communication system configured to execute the following steps: replacing a high-priority packet with a dummy packet; and transmitting a packet owned by a Lower MAC to a terminal via a link. preferable.

A second aspect of the present disclosure provides a wireless communication system that includes a base station with a multilink function and a terminal with a multilink function, and is configured such that the base station and the terminal communicate via a plurality of links. A wireless communication method in which a base station includes an Upper MAC that receives packets generated in an upper layer and a Lower MAC that exists for each link, and transmits a dummy packet from the Upper MAC to the Lower MAC. Preferably, the wireless communication method comprises the steps of: replacing a high-priority packet with a dummy packet; and transmitting a packet possessed by the Lower MAC to a terminal via a link.

A third aspect of the present disclosure includes an Upper MAC that receives packets generated in an upper layer and a Lower MAC that exists for each link, and a function of transmitting a dummy packet from the Upper MAC to the Lower MAC; It is preferable that the wireless communication device has a function of replacing a high-priority packet with a dummy packet and a function of transmitting a packet possessed by a Lower MAC via a link.

According to the first, second, and third aspects of the present disclosure, the queuing delay of high-priority packets can be reduced.

1 is a diagram illustrating a configuration example of a wireless communication system without a multilink function. 1 is a diagram illustrating a configuration example of a wireless communication system when there is a multilink function. 3 is a flowchart showing a multi-link setup procedure. FIG. 3 is a diagram illustrating packet categorization processing. 1 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 1 of the present disclosure. 3 is a flowchart illustrating a packet processing method according to Embodiment 1 of the present disclosure. 3 is a flowchart illustrating a dummy packet management method according to Embodiment 1 of the present disclosure. 1 is a block diagram showing the device configuration of a base station according to Embodiment 1 of the present disclosure. FIG. 1 is a block diagram showing the device configuration of a terminal according to Embodiment 1 of the present disclosure. FIG. 3 is a table showing an example of data held by a dummy packet management unit according to Embodiment 1 of the present disclosure. FIG. 2 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 2 of the present disclosure. FIG. 3 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 3 of the present disclosure.

Embodiment 1
[Conventional wireless communication system]
Prior to describing the first embodiment, a conventionally used multilink will be described. FIG. 1 is a diagram showing an example of the configuration of a wireless communication system without a multilink function. That is, the wireless communication system 500 transmits multiple types of packets using one link.

The wireless communication system 500 includes a base station 2. The base station 2 transmits the high priority packet 4 generated in the upper layer to the MAC unit 12. The MAC unit 12 includes a queue 8 . The queue 8 holds received packets in an ordered manner so that they can be transmitted in the order in which they are received. When the frame transmission right is acquired, the order of the packets held in the queue 8 is checked, and the packets are transmitted in order starting from the front row. Note that when the applied wireless communication system is Wi-Fi (registered trademark), the base station corresponds to an access point.

The base station 2 has only one queue 8 because it does not have a multilink function. Therefore, even if a high-priority packet 4 occurs, if the queue 8 already has multiple packets 6, the high-priority packet 4 is ordered so that it becomes the last packet held in the queue 8. I do.

The MAC unit 12 transmits the packet to the PHY 10. More specifically, among the packets, the one that comes to the forefront in the order of the packets held by the queue 8 is transmitted to the PHY 10. That is, the high priority packet 4 transmitted to the PHY 10 is transmitted to the terminal 16 after all the packets 6 held in the queue 8 up to that point have been transmitted. Note that since the base station 2 does not have a multilink function, it also includes only one PHY 10.

As described above, in the wireless communication system 500 that uses only one link, even when the high priority packet 4 occurs, no process is performed to give priority to it.

FIG. 2 is a diagram showing a configuration example of a wireless communication system when there is a multilink function. Here, a wireless communication system 600 that forms three links by using a multilink function will be described.

The wireless communication system 600 includes a base station 2. The base station 2 transmits the high priority packet 4 generated in the upper layer to the MAC unit 12. The MAC unit 12 includes an Upper MAC 18 and

Lower MACs

20a, 20b, and 20c that exist for each link.

The MAC unit 12 first receives the high priority packet 4 at the Upper MAC 18. The Upper MAC 18 distributes the high priority packet 4 to any one of the

Lower MACs

20a, 20b, and 20c. More specifically, the high-priority packet 4 is ordered so that it becomes the last packet held in the queue provided by the assigned Lower MAC. This distribution is performed based on predetermined processing. Here, it is assumed that among the

queues

8a, 8b, and 8c provided in each of the

Lower MACs

20a, 20b, and 20c, processing is performed to allocate to the queue with the shortest waiting time. Note that the waiting time in this case changes depending on the number or size of packets 6 that each queue has.

The MAC unit 12 transmits the packet to the PHY unit 14. This PHY unit 14 includes

PHYs

10a, 10b, and 10c. More specifically, among the packets, the one that comes to the forefront in the order of the packets held by each of the

queues

8a, 8b, and 8c is transmitted to each of the

PHYs

10a, 10b, and 10c. That is, the high-priority packet 4 is transmitted to the terminal 16 after all the packets 6 held in the sorted queue have been transmitted.

As mentioned above, the high priority packet 4 is distributed to the queue with the shortest waiting time. Therefore, compared to the wireless communication system 500 that uses only one link, it is possible to increase the possibility that transmission to the PHY will be performed with a shorter waiting time.

In this way, throughput and delay characteristics can be improved by transmitting different data simultaneously in multiple frequency bands using the multilink function. However, the Lower MACs of all links used in the multilink function may already have multiple transmission packets. The high-priority packet generated in this case cannot be immediately delivered to the PHY and transmitted no matter which link is used. That is, a problem arises in which a queuing delay occurs. The present disclosure solves this problem.

FIG. 3 is a flowchart showing the multilink setup procedure. The dummy

packet management units

64 and 74, which will be described later, perform the processing shown in FIG. 3 to perform settings so that wireless communication can be performed via specific links. This allows the wireless communication system to establish multi-link communication.

FIG. 4 is a diagram showing packet categorization processing. Wireless communication systems transmit multiple types of packets. Here, a process is shown in which the plurality of types of packets are identified for each traffic in the STA unit, which will be described later.

A packet to which a MAC header is added in the upper layer is input to one of the

queues

22, 24, 26, and 28. The input destination queue is determined by the TID (Traffic Indicator) included in the MAC header. For example, when WME (Wireless Multimedia Extensions) prioritizes, queue 22 is a VO category related to audio, queue 24 is a VI category related to video, queue 26 is a BE category related to best effort, and queue 28 is a BK category related to background. can be identified.

The packets input to each queue are input to the CSMA/

CA sections

32, 34, 36, 38, and 40. Each CSMA/CA unit uses unique access parameters to access the channel and perform CSMA/CA. The unique access parameters are, for example, Cwmax, Cwmin, AIFS, and TXOPlimit. When each CSMA/CA unit obtains the transmission right, it acquires a MAC frame from each queue and outputs it to the internal conflict resolution unit 42.

Note that the CSMA/

CA units

32, 34, 36, and 38 process those that have arrived at the front of the

queues

22, 24, 26, and 28. The CSMA/CA unit 40 processes low delay data.

When multiple CSMA/CA units acquire transmission rights at the same time, the internal conflict resolution unit 42 selects and outputs the one with the highest priority.

[Wireless communication system of the present disclosure]
FIG. 5 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 1 of the present disclosure. The wireless communication system according to the first embodiment differs from the conventional example in that a dummy packet is periodically transmitted to any of the links used in the multilink function. Here, a wireless communication system 100 that forms three links by using a multilink function will be described.

The wireless communication system 100 transmits packets using the same procedure as the wireless communication system 600. However, the wireless communication system 100 periodically transmits dummy packets 44 in addition to the packets generated in the upper layer. Dummy packet 44, like packet 6 and high priority packet 4, forms a queue. When the head of the queue is reached, the countdown of the CW (Contention Window) value is started.

If a high priority packet 4 is generated during the countdown of the CW value, a process is performed to replace the high priority packet 4 with a dummy packet 44. This process may be performed immediately after the high priority packet 4 is generated, or when the CW value reaches a specific value.

If no high-priority packet is generated during the countdown of the CW value, it is treated as having completed the transmission process of the dummy packet 44. First, the transmission process of the dummy packet 44 is canceled at the timing when the CW value becomes 0 or at the timing when the CW value becomes a specific value.

After canceling the transmission process of the dummy packet 44, the next packet after the dummy packet 44 is moved to the head of the queue. Then, the CW value of the packet is not counted down, and the frame transmission processing is directly performed. That is, the packet at the head of the queue in which the dummy packet 44 existed performs frame transmission processing instead of the dummy packet 44.

After canceling the transmission process of the dummy packet 44, the packet whose CW value was counted down at the beginning of a different link is moved to the link where the dummy packet 44 existed, and the frame transmission process is executed. It's okay.

Alternatively, only the process of canceling the transmission process of the dummy packet 44 may be performed. That is, after canceling the transmission process of the dummy packet 44, the next packet after the dummy packet 44 is moved to the head of the queue as usual. Then, the countdown of the CW value of the packet may be started, and then the normal frame transmission processing may be performed.

[Packet processing method of the present disclosure]
This section describes how to process packets. FIG. 6 is a flowchart illustrating a packet processing method according to Embodiment 1 of the present disclosure. First, in step 100, the Upper MAC 18 receives a packet from an upper layer.

Next, in step 102, it is checked whether the received packet has a high priority. The determination of priority is performed by the MLD unit 59 of the base station, which will be described later. TID may be used for this determination. For example, a method may be considered in which a packet to which a prespecified TID or a TID indicating a higher priority than the TID is assigned is determined to be a "high priority packet." If the priority is high, proceed to step 104. If the priority is not high, proceed to step 108.

In step 104, it is checked whether dummy packets exist for all links used in the wireless communication system. In the case of the wireless communication system 100, it is checked whether dummy packets exist in all links including each of the

Lower MACs

20a, 20b, and 20c. If a dummy packet exists, proceed to step 106. If there is no dummy packet, the process proceeds to step 108.

In step 106, the dummy packet and the high priority packet are exchanged. For example, a process is performed in which the tags indicating the order of packets held in the queue of the Lower MAC 20a are replaced with the dummy packet 44 and the high priority packet 4. Alternatively, the bit information of the high priority packet 4 is transferred onto the bit information of the dummy packet 44. This process may be performed immediately after the high priority packet 4 is generated, or when the CW value reaches a specific value.

In step 108, normal queuing is performed. That is, the packets held by each Lower MAC are transmitted in order, regardless of their types.

As described above, in the first embodiment, a dummy packet is periodically transmitted to any of the links used in the multilink function. If a high-priority packet occurs at a later timing, the high-priority packet and the dummy packet are replaced. This makes it possible to shorten the queuing delay no matter when a high-priority packet occurs.

Note that the size of the dummy packet may be specified in advance as a default size. For example, the maximum size that can be set may be specified. Alternatively, the size may be determined by referring to the size of a high-priority packet received by the Upper MAC immediately before. If the sizes of the dummy packet and the high-priority packet do not match, processing such as padding may be performed during replacement or aggregation processing.

[How to manage dummy packets according to the present disclosure]
An example of how to manage dummy packets will be shown. FIG. 7 is a flowchart illustrating a dummy packet management method according to Embodiment 1 of the present disclosure. Here, an example will be shown in which the base station 2 that forms links using the multilink function transmits dummy packets 44 to three links in order. It is assumed that numbers 1, 2, and 3 are assigned in advance to the three links including the

Lower MACs

20a, 20b, and 20c.

First, in step 110, the Upper MAC 18 generates a dummy packet 44 and transmits it to the link 1. When the dummy packet 44 reaches the head of the link 1 queue, a countdown of the CW value is started. After a certain period of time has elapsed, the CW value of link 1 becomes 0, as in step 112.

Continuing, in step 114, the Upper MAC 18 generates a dummy packet 44 and transmits it to the link 2. When the dummy packet 44 reaches the head of the link 2 queue, the CW value starts counting down. After a certain period of time has elapsed, the CW value of link 2 becomes 0, as in step 116.

Continuing, in step 118, the Upper MAC 18 generates a dummy packet 44 and transmits it to the link 3. When the dummy packet 44 reaches the head of the queue of the link 3, a countdown of the CW value is started. After a certain period of time has elapsed, the CW value of link 3 becomes 0, as in step 120. After this, the process returns to step 110 and the same process is repeated.

Note that the timing at which the dummy packet 44 shown in steps 112, 116, and 120 is generated may be when the CW value becomes a specific value other than 0.

Furthermore, the link through which the dummy packet 44 is sent may be selected based on statistics measured in advance. More specifically, a method of selecting based on a PER (Packet Error Rate) value or an average CW value calculated from statistics measured in advance may be considered. For example, by transmitting the dummy packet 44 to the link with the lowest PER value, the high priority packet 4 is more likely to be transmitted to the link with the lowest PER value. That is, it becomes easier to shorten the queuing delay of the high-priority packet 4.

According to the above procedure, the size of the occupied queue by dummy packets can be distributed by appropriately changing the link for transmitting dummy packets. Furthermore, since the delay time of each link changes over time, by determining the destination based on this information, it is possible to improve the probability that a high-priority packet can be distributed to a link with a small delay time.

[Configuration of device included in wireless communication system of the present disclosure]
FIG. 8 is a block diagram showing the device configuration of a base station according to Embodiment 1 of the present disclosure. First, data transmission from the base station 2 to another terminal will be explained.

The base station 2 includes an LLC section 58. The LLC unit 58 is a sublayer that performs logical link control. LLC section 58 outputs the input packet to MLD section 59.

The MLD section 59 is a link management section and includes a data processing section 60. The data processing unit 60 processes data and outputs the results to the base station measurement unit 62 and dummy packet management unit 64. The base station measurement unit 62 records the link number through which the dummy packet is sent and measures the PER of each link.

The dummy packet management unit 64 selects a link to transmit the dummy packet. This link selection is performed based on information about each link obtained by the base station measuring section 62. Then, the dummy packet management unit 64 transmits the dummy packet to the STA unit corresponding to the selected link.

Additionally, the dummy packet management unit 64 replaces high priority packets and dummy packets. Further, the dummy packet management unit 64 performs the multilink setup described in FIG. 3.

The

STA units

66a, 66b, and 66c are transmitting/receiving units, and receive packets input from the dummy packet management unit 64. Then, the MAC frame included in the packet is transmitted to another terminal as a wireless frame. Note that data transmission and reception with other terminals is performed via an antenna.

Next, data transmission from another terminal to the base station 2 will be explained. The

STA sections

66a, 66b, and 66c output wireless frames received from other terminals to the dummy packet management section 64.

The dummy packet management unit 64 processes the header and the like from the MAC frame included in the input wireless frame, and outputs the obtained data to the data processing unit 60. The data processing section 60 outputs this data to the LLC section 58.

FIG. 9 is a block diagram showing the device configuration of a terminal according to Embodiment 1 of the present disclosure. First, data transmission from the terminal 16 to another terminal will be explained.

The terminal 16 includes an LLC section 68. LLC section 68 outputs the input packet to MLD section 69 .

The MLD section 69 includes a data processing section 70. The data processing unit 70 processes packets and outputs the results to the terminal measurement unit 72 and the dummy packet management unit 74. The terminal measurement unit 72 measures the PER etc. of each link as necessary. This measurement result is notified to the base station measurement unit 62 included in the base station within the wireless communication system. Note that the terminal measuring section 72 may have the same functions as the base station measuring section 62. The dummy packet management section 74 has the same functions as the dummy packet management section 64.

The

STA units

76a, 76b, and 76c receive packets input from the dummy packet management unit 74. Then, the MAC frame included in the packet is transmitted to another terminal as a wireless frame. Note that data transmission and reception with other terminals is performed via an antenna.

Next, data transmission from another terminal to the terminal 16 will be explained. The

STA units

76a, 76b, and 76c output wireless frames received from other terminals to the dummy packet management unit 74.

The dummy packet management unit 74 processes the header and the like from the MAC frame included in the input wireless frame, and outputs the obtained data to the data processing unit 70. The data processing section 70 outputs this data to the LLC section 68.

Note that the terminal 16 may be configured without the dummy packet management section 74. In this case, the terminal 16 does not generate a dummy packet. The terminal 16 notifies the base station only of information such as PER measured on the terminal side.

FIG. 10 is a table showing an example of data held by the dummy packet management unit according to Embodiment 1 of the present disclosure. The dummy packet management unit holds various data for each link in order to manage dummy packets. Here, as an example, a data group in a base station including three STA sections is shown.

In this example, STAs 1, 2, and 3 all support the multilink function. However, only STAs 1 and 2 are used for multilink transmission. Only STA1 is used as the destination of the dummy packet. STA1 currently has a dummy packet, and its CW value is 6. Based on these data, packets are sorted.

The value of PER is also held here. It can be seen that the PERs shown by the three STAs are different values. It is also possible to set a destination link for the dummy packet based on this PER value.

Embodiment 2
FIG. 11 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 2 of the present disclosure. The wireless communication system according to the second embodiment differs from the first embodiment in that a plurality of terminals are targets of wireless communication with one base station.

The wireless communication system 200 includes a base station 2. Base station 2 performs wireless communication with

terminals

16a, 16b, and 16c. With this configuration, it is possible to shorten the queuing delay when a high-priority packet occurs even in wireless communication that targets a wide range and targets multiple terminals.

The determination of the link for transmitting dummy packets and the transmission rate of dummy packets may be determined by referring to the PER of all terminals 16 or the PER of a specific terminal 16. An example of a method for selecting a particular terminal 16 of interest is a method of selecting a terminal with the highest high-priority frame transmission rate.

Furthermore, the selection of the link for transmitting the dummy packet may be set independently by the base station 2 and the terminal 16. Alternatively, the base station 2 and a specific terminal 16 may be set to be synchronized or not synchronized.

Note that it is not necessary to send dummy packets to all links used in the multilink function. For example, if there is a link where many legacy base stations exist, dummy packets may not be sent to that link.

Embodiment 3
FIG. 12 is a diagram illustrating a configuration example of a wireless communication system according to Embodiment 3 of the present disclosure. The wireless communication system according to the third embodiment differs from the first embodiment in that a controller that bundles a plurality of base stations is installed.

The wireless communication system 300 includes a controller 46. Controller 46 is connected to

base stations

2a and 2b. The base station 2a performs wireless communication with the terminal 16a. The base station 2b performs wireless communication with the terminal 16b. With this configuration, it is possible to shorten the queuing delay when a high-priority packet occurs even in wireless communication that targets a wide area and includes multiple base stations.

Note that the method for selecting the link through which the dummy packet is sent may be independently specified within each base station and terminal. Alternatively, the controller 46 may specify a link for transmitting a dummy packet for the connected

base stations

2a and 2b.

In the above case, the controller 46 may specify the link to which the dummy packet is to be transmitted based on the degree of congestion or PER of the channel used by the terminal 16. For example, links may be specified so that dummy packet ratios do not vary between channels.

2, 2a, 2b base station 4 high priority packet 6

packet

16, 16a, 16b terminal 44 dummy packet 46

controller

100, 200, 300, 500, 600 wireless communication system

Claims

A wireless communication system comprising a base station having a multi-link function and a terminal having a multi-link function, the base station and the terminal communicating through a plurality of links,
The base station is
an Upper MAC that receives packets generated in the upper layer;
Lower MAC that exists for each link,
dummy packet transmission processing for transmitting a dummy packet from the Upper MAC to the Lower MAC;
a process of replacing a high-priority packet with the dummy packet;
A wireless communication system configured to perform the following steps: transmitting a packet possessed by the Lower MAC to the terminal via the link.
The dummy packet transmission process includes:
The wireless communication system according to claim 1, further configured to perform a process of determining the size of the dummy packet by referring to the size of the high priority packet received by Upper MAC immediately before.
The dummy packet transmission process includes:
a process of transmitting the dummy packet to different links at regular intervals;
The wireless communication system according to claim 1, further comprising at least one of: transmitting the dummy packet to a link selected based on statistics measured in advance.
the terminal includes a plurality of terminals,
The wireless communication system according to claim 1, wherein the base station performs wireless communication with the plurality of terminals.
the base station includes a plurality of base stations,
comprising a controller that controls the plurality of base stations,
The wireless communication system according to claim 1, wherein the controller specifies a destination of the dummy packet.
The terminal is
an Upper MAC that receives packets generated in the upper layer;
Lower MAC that exists for each link,
a process of transmitting a dummy packet from the Upper MAC to the Lower MAC;
a process of replacing a high-priority packet with the dummy packet;
The wireless communication system according to claim 1, wherein the wireless communication system is configured to perform a process of transmitting a packet included in the Lower MAC to the terminal via the link.
A wireless communication method carried out by a wireless communication system comprising a base station having a multi-link function and a terminal having a multi-link function, the base station and the terminal communicating through a plurality of links, ,
The base station,
an Upper MAC that receives packets generated in the upper layer;
Lower MAC that exists for each link,
transmitting a dummy packet from the Upper MAC to the Lower MAC;
replacing a high-priority packet with the dummy packet;
A wireless communication method comprising: transmitting a packet possessed by the Lower MAC to the terminal via the link.
an Upper MAC that receives packets generated in the upper layer;
Equipped with a Lower MAC that exists for each link,
a function of transmitting a dummy packet from the Upper MAC to the Lower MAC;
a function of replacing a high-priority packet with the dummy packet;
A wireless communication device comprising: a function of transmitting a packet possessed by the Lower MAC via the link.