WO2014169650A1

WO2014169650A1 - Downlink data sending and receiving method, access point (ap), and station (sta)

Info

Publication number: WO2014169650A1
Application number: PCT/CN2013/087408
Authority: WO
Inventors: 杨绿溪; 王敏; 杨讯
Original assignee: 华为技术有限公司
Priority date: 2013-04-17
Filing date: 2013-11-19
Publication date: 2014-10-23
Also published as: CN104113905B; CN104113905A

Abstract

Disclosed are a downlink data sending and receiving method, an access point (AP), and a station (STA). The downlink data sending method comprises: the AP receiving a first sending allowance message sent by the STA, the first sending allowance message comprising identifiers of all basic service sets (BSS) covering the STA (101); the AP determining, according to the first sending allowance message, a starting time for the AP to send downlink data, so that the starting time determined by the AP is the same as a starting time determined by an AP of another BSS in the first sending allowance message (102); and the AP starting sending downlink data at the starting time determined by the AP (103). When the AP has downlink data to be sent, each AP determines, according to the received first sending allowance message, a starting time for sending data, so that by enabling that the starting time determined by each AP is the same, it is ensured that each AP can send data synchronously, thereby avoiding mutual interference caused by that each AP sends data asynchronously in an overlapping area.

Description

Downlink data transmission and reception method and its access point AP and station STA This application is submitted to the Chinese Patent Office on April 17, 2013, the application number is 201310133153.9, and the invention name is "downlink data transmission and reception method and its access point. Priority of the Chinese Patent Application for AP and Site STA, the entire contents of which are incorporated herein by reference. The present invention relates to the field of wireless communication technologies, and in particular, to a downlink data transmission and reception method and an access point AP and a station STA. Background technique

In the 802.11 specification, an access point (AP) and a plurality of stations (Stations, referred to as STAs) associated with an AP form a basic service set (BSS). Typically, the STA in the wireless signal coverage of the AP is associated with the AP.

Wireless Local Area Networks (WLAN) defined by 802.11 utilizes Carrier Sense Multiple Access with Collision Avoidance (CSMA\CA) to enable multiple stations to share wireless channels, but A random access method cannot guarantee synchronization between the transmitting nodes.

In practical applications, it is common for multiple BSSs to overlap in the coverage area, thus forming an Overlay BSS (OBSS). When multiple APs are located separately

Multiple STAs in the OBSS transmit data at the same time, and they interfere with each other. In order to coherently receive signals at the receiving end and eliminate interference, strict time synchronization and frequency synchronization of each transmitting node are required. For example, STA1 and STA2 are located in the OBSS, the API sends data to STA1, and AP2 sends data to STA2. At this time, two STA1 and STA2 interfere with each other. In order to eliminate interference at the receiving end (ie, STA), interference alignment must be ensured. Ensure that the frequency of the sender's time is synchronized. SUMMARY OF THE INVENTION The present invention provides a downlink data transmission and reception method, and an access point AP and a station STA, It is used to solve the problem that data of multiple APs received by STAs located in an overlapping area in the prior art is out of synchronization.

A first aspect of the present invention provides a downlink data sending method, including:

The access point AP receives the first allowable sending message sent by the STA, where the first allowed sending message includes an identifier of all basic service sets BSS covering the STA;

Determining, by the AP, the start time of the downlink data sent by the AP according to the first allowed sending message, so that the start time determined by the AP and the start time determined by the APs of other BSSs in the first allowed sending message In the first possible implementation manner of the first aspect of the present invention, the determining, by the AP, the start time of the downlink data sent by the AP according to the first permission to send message includes:

Determining, by the AP, an order of the BSSs corresponding to the BSSs in the first allowed sending message; determining, by the AP, the starting time and the waiting time according to the sequence, determining the starting time according to the starting time and the waiting time.

In a second possible implementation manner of the first aspect of the present invention, before the receiving, by the AP, the first allowed sending message sent by the STA, the method further includes:

If the AP needs to send the downlink data, it identifies whether the downlink channel to be used is idle. If the AP identifies that the downlink channel is idle, the AP sends the downlink data to the STA that is to send the downlink data. The first request of the initiator sends a message to indicate that the first allowed sending message sent by the STA identifier corresponds to an initiator using the downlink channel.

In a third possible implementation manner of the first aspect of the present invention, when the AP needs to send downlink data, identifying whether the downlink channel to be used is idle includes:

When the AP needs to send downlink data, it is determined whether the first allowed sending message corresponding to the downlink channel to be used is received;

If yes, determining that the downlink channel is not idle, and determining a release time of the downlink channel according to the estimated estimated time carried in the first allowed sending message;

If not, it is determined that the downlink channel is idle.

In a fourth possible implementation manner of the first aspect, the determining, by the AP, the start time and the waiting time according to the sequence include:

Determining, according to the first allowed sending message, whether the AP corresponds to using the The initiator of the line channel;

If yes, the AP determines that the time for receiving the first allowed sending message is an initial time, and determines, according to the first allowed sending message, a waiting time for sending downlink data by itself;

If not, the AP sends a second request sending message according to the sequence, and receives the returned second allowed sending message, and uses the time for receiving the second allowed sending message as the starting time, and according to the first permission Sending a message to determine a waiting time for sending the downlink data by itself, where the second request sending message is used to indicate that the AP does not use the initiator of the downlink channel, to indicate that the second allowed sending message sent by the STA identifier is not Corresponding to the initiator using the downlink channel.

In a fifth possible implementation manner of the first aspect, the determining, by the AP, the waiting time for sending downlink data according to the first allowed sending message includes:

Obtaining, by the AP, a duration T _RTS that the STA receives the first request sending message, and acquiring a duration T _CTS that the STA sends the first allowed sending message according to the first request sending message; A number N of BSSs allowed to be transmitted in the message, and its own sequence number n in each BSS, the waiting time is determined based on the following formula:

Ί' = {N - n) x T + T _SIFS

Where = T _{CTS +} T _{RTS +} 2 x T _slFS , T _SIFS is the short frame interval.

In a sixth possible implementation manner of the first aspect, the sending, by the AP, the second request sending message according to the sequence includes:

The AP calculates, according to the sequence number n in each BSS, the waiting time required to send the second request to send information based on the following formula:

Wherein, = T _CTS + T _RTS + 2 x TT _SffS is a short frame interval, T _RTS is a duration for receiving the first request to send a message, and T _CTS is to send the first allowed transmission according to the first request sending message The length of the message.

In a seventh possible implementation manner of the first aspect of the present disclosure, the AP acquires a duration T _RTS that the STA receives the first request sending message, and obtains, by the STA, the sending the message according to the first request sending message. The length of time T _CTS allowed to send a message includes:

Determining, by the AP, the time length T _RTS that the STA receives the first request sending message from the first allowed sending message, and acquiring, by the STA, the duration of sending the first allowed sending message according to the first request sending message T _CTS . With reference to the first aspect of the present invention and the first to seventh possible implementation manners of the first aspect, in the eighth possible implementation manner of the first aspect, the BSS is identified as a MAC address of the AP.

A second aspect of the present invention provides a downlink data receiving method, including:

The STA receives the request sending message sent by the access point AP;

And the STA sends an allowable sending message according to the request sending message, where the allowed sending message carries an identifier of all basic service sets BSS covering the STA, and sends the permission sending message to the AP to indicate the The AP determines, according to the allowed sending message, a start time for sending the downlink data, where the start time determined by the AP corresponding to each BSS in the allowed sending message is the same;

The STA receives downlink data according to the determined start time.

In a first possible implementation manner of the second aspect of the present invention, the STA generates an allow-to-send message according to the request sending message, where the allowed sending message carries an identifier of all basic service sets BSS covering itself, and The sending, by the AP, the permission to send the message includes:

The STA carries the identifiers of the APs corresponding to all the BSSs of the BSS in the allowed transmission message in sequence, and carries the number of all BSSs;

The STA sends the permission to send a message.

In a second possible implementation manner of the second aspect of the present invention, the method further includes:

When the STA accesses the network and changes its physical location, it scans all of the BSSs covering itself and records them.

With reference to the second aspect of the present invention and the first and second possible implementation manners of the second aspect, in a third possible implementation manner of the second aspect of the present invention, And sending the message, the identifier of the basic message set BSS that covers the self-service, and the sending the message to the AP includes:

Determining, by the STA according to the sending request message, whether it is sent by an initiator using a downlink channel;

If yes, the STA carries the identifier of all BSSs that cover itself in the permission to send message, and identifies that the allowed to send message corresponds to the initiator that uses the downlink channel;

If not, the STA carries the identifier of all BSSs covering itself in the permission to send message, and identifies that the allowed transmission message does not correspond to the initiator that uses the downlink channel;

The STA broadcasts the permission to send a message. A third aspect of the present invention provides an access point AP, including:

a receiving module, configured to receive a first allowed sending message sent by the station STA, where the first allowed sending message includes an identifier of all basic service sets BSS covering the STA; a start time determining module, configured to Determining, by the first permission sending message, a start time of the downlink data sent by the AP, so that the start time determined by the AP is the same as the start time determined by the APs of other BSSs in the first allowed sending message;

And a sending module, configured to start sending downlink data at a determined start time.

In a first possible implementation manner of the third aspect of the present invention, the start time determining module includes:

a sequence determining unit, configured to determine an order of the BSS corresponding to the AP in the first allowed sending message;

And a time determining unit, configured to determine an initial time and a waiting time according to the sequence, and determine the starting time according to the starting time and the waiting time.

In a second possible implementation manner of the third aspect of the present invention, the AP further includes: a channel identification module, configured to identify, when the AP needs to send downlink data, whether the downlink channel to be used is idle;

If the AP identifies that the downlink channel is idle, sending, to the STA that is to send the downlink data, a first request sending message indicating that the AP is an initiator that uses the downlink channel, to indicate that the STA identifier is sent. A permission to send a message corresponds to the initiator using the downlink channel.

In a third possible implementation manner of the third aspect of the present invention, the channel identification module is specifically configured to:

When the AP needs to send downlink data, it is determined whether a first allowed sending message corresponding to the downlink channel to be used is received;

If not, it is determined that the downlink channel is idle.

In a fourth possible implementation manner of the third aspect of the present invention, the time determining unit is specifically configured to:

Determining, according to the first allowed to send message, whether the AP corresponds to an initiator using the downlink channel; If yes, determining that the time for receiving the first allowed sending message is an initial time, and determining, according to the first allowed sending message, a waiting time for sending downlink data by itself;

If not, sending the second request sending message according to the sequence, and receiving the returned second allowed sending message, receiving the second allowed sending message as the starting time, and determining according to the first allowed sending message The waiting time length of the downlink data sent by the AP, where the second request sending message is used to indicate that the AP does not use the initiator of the downlink channel, to indicate that the second allowed sending message sent by the STA identifier does not correspond. The initiator of the downlink channel is used.

In a fifth possible implementation manner of the third aspect of the present invention, the determining, by the time determining unit, the waiting time for the AP to send the downlink data according to the first allowed sending message includes: acquiring, by the STA, the first request to send a duration T _{RTS of the} message, obtaining a duration T _CTS when the STA sends the first allowed sending message according to the first request sending message;

And determining, according to the following formula, the waiting time according to the number N of each BSS in the first allowed sending message, and the sequence number n of the AP in each BSS:

Ύ' - (N - n) x T + T _SIPS

Where = T _{CTS +} T _{RTS +} 2 x T _SIFS , T _SIFS is the short frame interval.

In a sixth possible implementation manner of the third aspect of the present invention, the sending, by the time determining unit, the second request sending message according to the sequence includes:

According to the sequence number n of the AP in each BSS, the waiting time required to send the second request to send information is calculated based on the following formula:

Wherein, T = T _CTS + T _RTS + 2 x TT _SffS is a short frame interval, T _RTS is a duration for receiving the first request to send a message, and T _CTS is to send the first permission according to the first request sending message The length of time the message was sent.

In a seventh possible implementation manner of the third aspect of the present invention, the acquiring, by the STA, a duration T _{RTS of} receiving the first request sending message, acquiring, by the STA, sending the first message according to the first request sending message The length of time allowed to send a message T _CTS includes:

Obtaining, by the first allowed sending message, the time length T _RTS that the STA receives the first request sending message, and acquiring, by the STA, the duration T _{CTS of} sending the first allowed sending message according to the first request sending message.

In conjunction with the third to seventh possible implementations of the third and third aspects of the present invention, In an eighth possible implementation manner of the third aspect of the present invention, the BSS identifier is an AP

MAC address.

A fourth aspect of the present invention provides a station STA, including:

a request sending message receiving module, configured to receive a request sending message sent by the access point AP, and a sending module, configured to send a message according to the request to generate an allow message to be sent, where the allowed sending message carries all the basics that cover the STA of the station An identifier of the service set BSS, and the sending the message to the AP, to indicate that the AP determines, according to the allowed sending message, a start time for sending downlink data, where the BSS corresponding to each BSS in the allowed message is sent The AP determines the same start time;

The data receiving module is configured to receive downlink data according to the determined start time.

In a first possible implementation manner of the fourth aspect of the present invention, the sending module includes: an information generating unit, configured to carry an identifier of an AP corresponding to all BSSs of the STA in the permission sending message in sequence, And carry the number of all BSS;

An information sending unit, configured to send the permission to send a message.

In a second possible implementation manner of the fourth aspect of the present invention, the method further includes:

The scanning module is configured to scan and record all BSSs of the STA when the STA accesses the network and when the physical location changes.

With reference to the fourth aspect of the present invention and the first to the second possible implementation manner of the fourth aspect, in a third possible implementation manner of the fourth aspect of the present invention, the method further includes:

a message identifying module, configured to identify, according to the sending request message, whether it is sent by an initiator using a downlink channel;

If yes, the sending module carries the identifier of all the BSSs that cover the STA in the permission to send message, and identifies that the allowed sending message corresponds to the initiator that uses the downlink channel; if not, the sending module Carrying an identifier of all BSSs covering the STA in an allow-to-send message, and identifying that the allowed-to-send message does not correspond to an initiator using the downlink channel;

The sending module sends the permission to send a message.

The embodiment of the present invention provides a method for transmitting and receiving downlink data, and an access point AP and a station STA. The method provided by the present invention, when the AP has downlink data to be sent, receives the STA broadcast and sends the first allowed to send the message. All APs are determined according to the first allowed message sent. The start time of sending data, when the start time is up, the data is sent, and the start time determined by each AP is the same, so that each AP can synchronously transmit data, and the data of each AP in the overlapping area is not synchronized. Mutual interference generated. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the embodiments or the description of the prior art will be briefly described below, and obviously, in the following description The drawings are only some of the embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

1 is a flowchart of Embodiment 1 of a method for transmitting downlink data according to the present invention;

2 is a flowchart of Embodiment 2 of a method for transmitting downlink data according to the present invention;

3 is a schematic diagram of overlapping between two BSSs according to an embodiment of the present invention;

4 is a flowchart of Embodiment 3 of a method for receiving downlink data according to the present invention;

5 is a schematic diagram of frequency offset when two APs simultaneously transmit data to one STA according to the present invention; FIG. 6 is a schematic diagram of sampling frequency offset when two APs simultaneously transmit data to one STA according to the present invention; FIG. 7 is a schematic diagram of a downlink data sending method according to the present invention; Flow chart of four;

Figure 8 is a schematic diagram of two APs simultaneously transmitting data;

9 is a schematic structural diagram of an AP according to Embodiment 5 of the present invention;

FIG. 10 is a schematic structural diagram of an AP according to Embodiment 6 of the present invention;

FIG. 11 is a schematic structural diagram of a STA according to Embodiment 7 of the present invention;

FIG. 12 is a schematic structural diagram of a STA according to Embodiment 8 of the present invention;

13 is a schematic structural diagram of an AP according to Embodiment 9 of the present invention;

FIG. 14 is a schematic structural diagram of a STA according to Embodiment 10 of the present invention. The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. The embodiments are a part of the embodiments of the invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without departing from the inventive scope are the scope of the present invention.

FIG. 1 is a flowchart of Embodiment 1 of a method for transmitting downlink data according to the present invention. The method provided in this embodiment may be performed by a downlink data transmitting device, and the downlink data transmitting device is integrated in the AP. It can be understood by those skilled in the art that the AP may be a network side device capable of providing wireless signal receiving and receiving services for the wireless terminal. The wireless signal provided by each AP can cover a certain range of locations. When multiple APs are arranged, each coverage area in a cellular form constitutes the entire wireless network. Areas where adjacent APs are adjacent may overlap with coverage areas. This overlapping area may be two AP overlaps or three or more AP overlaps. The STA may be located in this overlapping area and can receive two wireless signals sent by the AP, but the STA may select one of the APs to provide services based on a certain mechanism. For example, based on the power, the embodiment of the present invention does not limit this.

For STAs in the overlapping area, interference may occur when receiving downlink data. In order to eliminate interference by the interference alignment at the receiving end, each AP must be able to transmit data simultaneously to the STAs in the overlapping area. The embodiment solves this problem by providing a downlink data sending method, and any AP can perform this method.

The method provided in this embodiment includes the following steps:

Step 101: The AP receives the first allowed sending message sent by the STA, where the first allowed sending message includes an identifier of all basic service sets BSS covering the STA.

In this embodiment, the STA is located in an overlapping area of the plurality of BSS coverage areas. That is, the STA is located in the OBSS, so the STA can scan all the BSSs covering itself. The STA broadcasts the first allowable transmission message to the AP broadcasts of all the BSSs of the BSS. The APs of the BSSs can receive the first allowed transmission message, and the first allowed message is carried. Covers all the BSS's identity (Basic Service Set Identity, BSSID for short). The BSSID may be the Media Access Control (MAC) address of the AP, or may be other identifiers. Since the BSS corresponds to the ΑΡ, the BSS identifier can be determined. Before sending the downlink data to the STA that it is required to send, it will send a request to send message (Request To Send, RTS for short) to the STA, and receive the Clear To Send (CTS) message returned by the STA. After that, the AP can send data. In this step, the first CTS received by the AP may be the CTS that is triggered by the RTS being sent by itself, or may be triggered by the STA after the other AP sends the RTS. Step 102: The AP determines, according to the first allowed sending message, a start time for sending downlink data, so that the start time determined by the AP is the same as the start time determined by the APs of other BSSs in the first allowed sending message.

In this embodiment, the STA sends the first allowed sending message to all the APs that cover the STA. Therefore, after receiving the first allowed sending message, each AP determines, according to the first allowed sending message, if there is data to be sent. The start time of the downlink data is sent by itself, so that the start times determined by the respective APs are the same.

Step 103: The AP starts to send downlink data at the determined start time.

After determining the start time of sending downlink data, the AP waits for the start time to start transmitting downlink data. The start time determined by each AP is the same. Therefore, each AP is synchronized to send downlink data to the corresponding STA.

In the method provided in this embodiment, when the AP has downlink data to be sent, all APs that have received the STA broadcast and send the first allowable sending message determine the start time of the sending data according to the received first allowed sending message, when the start When the time is up, the data is sent, and the start time determined by each AP is the same, so that each AP can synchronously transmit data, and the mutual interference generated when each AP in the overlapping area is out of synchronization is avoided.

Each AP that has an overlapping area, if there is no need to simultaneously transmit downlink data, can be transmitted at different times, and interference does not occur. The technical solution of the embodiment of the present invention is mainly applicable to a situation in which each AP needs to occupy a certain downlink channel to transmit data at the same time. At this time, the STA sends an allow message to be sent, so that each AP knows that other APs in the overlapping area exist, so that the time is up to the same time. Start sending downstream data to ensure that data is sent synchronously. This interference is particularly obvious when the AP generates the same downlink channel transmission data. In the non-overlapping region, the AP can independently use the downlink channel, and in the overlapping region, there is a mechanism for each AP to compete to use the downlink channel, and the following will be implemented. The case is accompanied by a detailed description.

2 is a flowchart of Embodiment 2 of a method for transmitting downlink data according to the present invention. On the basis of Embodiment 1, this embodiment describes in detail how each AP determines the start time of sending data according to the first allowed transmission message. The method provided in this embodiment specifically includes the following steps:

Step 201: When the AP needs to send downlink data, identify whether the downlink channel to be used is idle. It should be noted that, due to the strong anti-interference capability of the Orthogonal Frequency Division Multiplexing (OFDM) technology, multiple adjacent BSSs can use the same frequency resource to transmit data, when multiple neighbors The BSS has overlapping cases. FIG. 3 is a schematic diagram of overlapping between two BSSs according to an embodiment of the present invention. As shown in FIG. 3, BSS1 and BSS2 have overlapping areas, that is, overlapping areas of two coverage areas in the figure, and STA1 and STA2 are in an overlapping area. When the API is sent from the data to the STA1, the AP2 can also send data to the STA2, and the two transmitting nodes interfere with each other. STAs located in the overlapping area can receive data transmitted by all APs covering the STA, and therefore, the data received by STA1 is interfered by STA2.

When the downlink data needs to be sent, the AP needs to identify whether the downlink channel to be used is idle. When the AP needs to send downlink data, it determines whether the first allowed transmission message corresponding to the downlink channel to be used is received. If the AP receives the first allowable sending message corresponding to the downlink channel to be used, the AP determines that the downlink channel is not idle, and the AP does not correspond to the initiator, and according to the estimated estimated time carried in the first allowed sending message. , determine the release time of the downlink channel. If no, that is, the AP does not receive the first allowed transmission message corresponding to the downlink channel to be used, it determines that the downlink channel is idle, and the AP corresponds to the initiator. Multiple APs may send RTS at the same time, and the AP that first receives the returned CTS will act as the initiator that initiates the use of the idle channel, and the other APs are non-initiators.

If the AP identifies that the downlink channel is idle, the STA sends a first request sending message indicating that the AP is the initiator that uses the downlink channel to the STA that is to send the downlink data, to indicate that the first allowed sending message sent by the STA identifier corresponds to using the downlink channel. Initiator.

Specifically, FIG. 3 is taken as an example. As shown in FIG. 3, for example, if the API has data to send to STA1, it is detected whether the channel is idle, and the API determines whether it receives the first allowed transmission corresponding to the downlink channel to be used. The message, if the API is not received, indicates that the downlink channel is idle. At this time, the API sends a first request sending message to the STA1, where the first request sending message is used to indicate that the API is the initiator that uses the downlink channel, and the STA1 receives the first request. After the message is sent, the first allowed sending message is broadcast to the API and the AP2, and the first allowed sending message is corresponding to the initiator of the downlink channel. Both the API and the AP2 can receive the first allowed transmission message returned by the STA1. If the AP2 also has data to send, the AP2 detects whether the channel is idle, and the AP2 detects that the first allowed transmission message corresponding to the downlink channel to be used is received. Therefore, it is determined that the downlink channel is not idle. In this embodiment, the API and the AP2 use the same downlink channel to transmit data. When the API uses the channel, the channel is occupied by the AP2, which is a non-idle channel.

Step 202: The AP receives the first allowed sending message sent by the STA, where the first allowed sending message includes an identifier of all BSSs that cover the STA.

When the AP corresponds to the initiator, the AP needs to send to the downlink after determining that the downlink channel is idle. After the data STA sends the first request to send the message, it can receive the first allowed sending message sent by the STA. In this embodiment, the STA sends a first permission to send message to the APs of all BSSs that cover the STA in a broadcast manner.

The first allowed sending message includes the identifiers of all BSSs covering the STA, so that each AP can know that it has overlapping areas with other BSSs after receiving the first allowed sending message.

Step 203: The AP determines an order of the BSS corresponding to the first allowed transmission message. In this embodiment, the first allowed transmission message carries not only the identifiers that cover all the BSSs of the STA, but also the BSS identifiers have a certain order. Specifically, the identifier of the BSS corresponding to the initiator AP is placed in the first place, and the order of the identifiers of other BSSs can be randomly placed. After receiving the first allowed transmission message, each AP parses and obtains the order of the BSS corresponding to itself in the first allowed transmission message.

Step 204: The AP determines the start time and the waiting time according to the sequence, and determines the start time according to the start time and the waiting time.

The AP identifies whether it corresponds to the initiator using the downlink channel according to the first allowed transmission message. Specifically, the AP determines whether it corresponds to the initiator according to the sequence of the BSS that is obtained in step 203. When the order of the BSS corresponding to the AP is in the first place, the AP determines that it corresponds to the initiator. If the order of the BSS corresponding to the AP is not the first, the AP determines that it does not correspond to the initiator.

If the AP determines that it corresponds to the initiator, the AP determines that the time for receiving the first allowed transmission message is the start time, and determines the waiting time for sending the downlink data according to the first allowed transmission message. Still taking FIG. 3 as an example, the API determines that it is the initiator, and the API acquires the duration T _RTS that the STA1 receives the first request to send the message, and obtains the duration T _CTS that the STA1 sends the first allowed to send the message according to the first request, and the AP may The time length T _{RTS at} which the STA receives the first request to send the message is parsed from the first allowed transmission message, and the duration T _{CTS of the} first allowed transmission message is sent according to the first request sending message.

After obtaining the T _RTS and the T _CTS , the API according to the number N of each BSS in the first allowed transmission message, and the sequence number n of each BSS in the BSS, the sequence number n indicates the order of the BSS in the first allowed transmission message, based on the next The formula determines the waiting time: T' = (N - _n ) xr + r _sra , where T = T _CTS + T _RTS + 2 x T _SIPS , T _SIFS is the short frame interval. In this embodiment, the first allowed sending message carries the T _RTS and the T _CTS , and the API can be parsed and obtained. It can be understood that T _RTS and T _CTS are both fixed for all APs. Therefore, the AP does not need to parse each time, and the AP can be pre- These lengths are configured and calculated based on these durations. In this embodiment, N is 2, and the order of BSS is 1. At this time, for the API, the waiting time is (2-1) *T+T _SIFS =T+T _SIFS .

If the AP determines that it does not correspond to the initiator, the AP sends a second request sending message according to the sequence of the BSS corresponding thereto, and receives the returned second allowed sending message, and the time for receiving the second allowed sending message is the starting time, and The waiting time for transmitting the downlink data is determined according to the first allowed transmission message. The second request sending message is used to indicate that the AP does not use the initiator of the downlink channel, to indicate that the second allowed sending message sent by the STA identifier does not correspond to the initiator that uses the downlink channel.

In this embodiment, AP2 determines that it does not correspond to the initiator, and AP2 sends a second request sending message to STA2 according to its own order in the first allowed sending message, and AP2 is based on its own sequence number n in each BSS. The following formula calculates the waiting time required to send a second request to send a message : " : Ύ "

T _CTS + T _RTS + 2 x T _SIFS , T _SIFS is a short frame interval, T _RTS is the length of time for receiving the first request to send a message, and T _CTS is the length of time for transmitting the first allowed to send message according to the first request sending message. In this embodiment, the order of AP2 is 2, therefore, the waiting duration is T'=(2-2)*T=0, that is, ΑΡ2 does not need to wait, and after receiving the first allowed sending message, it sends the first to STA2. The second request sends a message, and identifies that the second request sending message does not correspond to the initiator that uses the downlink channel, and after receiving the second request sending message, the STA2 sends a second allowed sending message to the ΑΡ2, and identifies the second allowed sending. The transmitted message does not correspond to the originator of the downlink channel. Then, after receiving the second message, the second transmission allowed message is not corresponding to the initiator that uses the downlink channel, and the time when the second permission to send the message is received is the start time.

After determining the start time, the ΑΡ2 determines the waiting time for sending the downlink data according to the first allowed transmission message. ΑΡ2, obtaining a duration T _{RTS at} which the STA1 receives the first request to send the message, acquiring a duration T _CTS that the STA1 sends the first allowed transmission message according to the first request sending message, according to the number N of each BSS in the first allowed sending message, and itself in each The sequence number n in the BSS determines the waiting time based on the following formula:

T _{CTS +} T _{RTS +} T _slFS , T _SIFS is a short frame interval. In this embodiment, the waiting time determined by the AP2 is _TSIFS , that is, the AP2 can send the downlink data after receiving the second allowed transmission message sent by the STA2.

In this embodiment, the API is the initiator. Therefore, the API determines that the time at which the first allowed message is sent is the start time, the waiting time is T+T _SIFS , and the start time determined by the API is the time after the start time is the waiting time. Point, that is, after receiving the first allowed message, the API waits for T+T _{SIF to} grow and starts to send data. The starting time determined by AP2 is the number returned by receiving STA2. Second, when the message is allowed to be sent, the waiting time determined by AP2 is T _SIFS . Therefore, the starting time of AP2 is the waiting time for sending the second request message plus the AP2 sending time after receiving the first allowed sending message. The duration of the second request transmission and the duration of receiving the second request permission message, plus the waiting time required to send the downlink data. The duration of the waiting for sending the second request sending message is 0, and the total waiting time is the sum of the waiting time ₈ for transmitting the downlink data and the duration for sending the second allowed sending message and the duration T for receiving the first allowed sending message, so the AP2 is receiving. After the first message is allowed to be sent, the T+T _{SIF is} waited for as the start time, and the downlink data is started.

Therefore, it can be seen that the start time of the API and AP2 calculation is the same, and when the start time is up, the API and AP2 can simultaneously transmit data.

Step 205: The AP starts to send downlink data at the determined start time.

Each AP starts to send downlink data when the determined start time expires. From step 204, it can be known that the start times determined by the APs are the same, and therefore, each AP can be guaranteed to transmit data synchronously.

It can be understood that, in this embodiment, when the AP2 has no data to transmit, the start time may not be calculated, and the API sends data when the start time expires. Of course, if AP2 does not send data, you can notify the API. The API can cancel the set start time and send the data directly. In the actual use process, since the request to send the message and the permission to send the message are very short, the time for sending the request and the time for receiving the transmission are also very short, so even if the AP2 does not notify the API that there is no data to send, for the API The waiting time is not long, and it will not cause waste of resources.

In the method provided by the embodiment, after receiving the first allowed sending message, the AP determines the start time and the waiting time according to the order of the BSS in the first allowed sending message, and waits according to the starting time and waiting time. The duration determines the start time. When the start time expires, the data is transmitted. By making the start times determined by the APs the same, it is ensured that each AP can transmit data synchronously.

4 is a flowchart of Embodiment 3 of the method for receiving downlink data according to the present invention. The method provided in this embodiment is performed by a downlink data receiving device, and the device may be integrated in a STA. The method provided in this embodiment includes the following steps:

Step 301: The STA receives a request sending message sent by the AP.

When the AP has data to send to the STA, it first sends a request to send a message to the STA, and the STA receives the request to send the message sent by the AP.

Step 302: The STA sends a message according to the request to generate an allow message to be sent, and the message is allowed to be sent. Carrying the identifier of all the BSSs that cover the BSS, and sending the permission to send the message to the AP, instructing the AP to determine the start time of sending the downlink data according to the permission to send the message, where the start time determined by the AP corresponding to each BSS in the allowed message is the same. .

After receiving the request to send the message sent by the AP, the STA carries the identifier of all the basic service set BSSs of the coverage in the allowed transmission message and broadcasts to each AP. Specifically, the STA will overwrite the AP corresponding to all the BSSs of the UE. The identifiers are carried in order to allow messages to be sent, and carry the number of all BSSs. The STA broadcast transmission allows the transmission of the message, so that the AP corresponding to all BSSs covering the STA can receive the permission to send the message.

When the STA accesses the network and changes its physical location, it scans all BSSs that cover itself and records them.

Step 303: The STA receives downlink data according to the determined start time.

The AP transmits data to the corresponding STA when the determined start time expires, and the STA receives the downlink data according to the determined start time.

In the method provided by the embodiment, after receiving the request sending message sent by the AP, the STA carries the identifier of all the BSSs that cover the BSS in the allowed sending message and broadcasts to each AP, so that each AP determines a start according to the allowed sending message. The sending time is the same as the starting time determined by the APs corresponding to all the BSSs that are allowed to be sent in the message. When the initial sending time expires, each AP simultaneously sends downlink data to the STAs to be sent data. By making the start times determined by the APs the same, it is ensured that each AP can transmit data synchronously.

In another embodiment of the present invention, on the basis of the third embodiment, the STA in step 302 carries the identifier of all the BSSs that cover the broadcast in the allowable sending message to each AP body:

First, the STA identifies whether it is transmitted by the initiator of the downlink channel based on the transmission request message. If yes, the STA carries the identifier of all BSSs covering itself in the permission to send message, and the identifier allows the sending message to correspond to the initiator using the downlink channel. If not, the STA carries the identity of all BSSs covering itself in the permission to send message, and identifies that the message allowed to be sent does not correspond to the initiator using the downlink channel.

Specifically, the request sending message sent by the AP to the STA may identify whether the request message corresponds to an initiator using the downlink channel. After obtaining the request message, the STA determines, according to the identifier, whether the AP corresponds to the initiator, and if it corresponds to the initiator of the downlink channel, the STA sends the allowed transmission message returned to each AP as corresponding to the initiator that uses the downlink channel. If the AP is based on the request If the message determines that the AP does not correspond to the initiator, it identifies that the allowed transmission message does not correspond to the initiator that uses the downlink channel. The STA broadcasts an Allow Send message to each AP broadcast.

Interference alignment is a key technology in next-generation WLANs. In these technologies, there are scenes in which multiple transmitters simultaneously transmit data. Only the transmitting nodes have strict time synchronization and frequency synchronization, and the receiving end can correctly demodulate the data. A main application scenario of the present invention is interference alignment. The data received by STAs located in the overlapping area may be interfered by other STAs in the overlapping area. Therefore, in order to coherently receive signals and eliminate interference at the receiving end, each of them must be guaranteed. The AP can guarantee time synchronization and frequency synchronization when transmitting data to the STA. The main problem solved by the present invention is the problem of time synchronization. The following briefly introduces the problem of frequency synchronization and the solution.

Since the oscillators of the respective transmitting nodes AP are independent, each carrier node has a carrier frequency offset with respect to the receiving node STA as shown in FIG. 5. FIG. 5 is a frequency offset of two APs simultaneously transmitting data to one STA according to the present invention. schematic diagram. The carrier frequency offset between API and STA1 is 4 i , and the carrier frequency offset of AP2 and STA1 is Δ/ ₂ . At the same time, since the sampling frequency of the receiving node is also different, the sampling timing frequency offset will be generated as shown in Fig. 6. Although the frequency offset can be estimated by the preamble and the interference between subcarriers is eliminated. However, this does not completely eliminate the frequency offset. Although this residual frequency offset does not cause serious ICI, it will cause a phase shift to the data OFDM symbol over time. The following will explain how the receiving end achieves synchronization in time and frequency through specific examples.

Figure Ί is a flowchart of Embodiment 4 of the downlink data sending method of the present invention. The present embodiment is based on the second embodiment. In this embodiment, the receiving end needs to eliminate interference by interference alignment, and how to implement time and frequency synchronization as an example. In detail, this embodiment is also illustrated by using the scenario shown in FIG. 3 as an example. Assume that the API corresponds to the initiator, and the AP2 does not correspond to the initiator. The method provided in this embodiment specifically includes the following steps:

Step 401: The API identifies that the downlink channel to be used is idle, and sends a first request sending message to STA1.

When the API has data transmission, it first identifies whether the downlink channel is idle. In this embodiment, the API is to use the initiator of the downlink channel, and the API determines that it does not receive the first allowed transmission message corresponding to the downlink channel to be used, and then determines. The downlink channel is idle, and sends a first request sending message to STA1, where the first request sending message indicates that the API is an initiator that uses the downlink channel. Specifically, the API may carry identifier information of one bit in the first request sending message to identify The first request to send message is sent by the initiator using the downlink channel.

Step 402: The STA1 receives the first request sending message sent by the API, and sends the message according to the first request. The message generation is allowed to send a message, and the identifier of all BSSs covering the self is carried in the message, and is broadcast and sent to each AP.

STA1 determines that it is in an overlapping area according to the BSSIDs of BSS1 and BSS2 that are scanned in advance. Specifically, if STA1 can only scan one BSS, it determines that it is in a non-overlapping area, and if STA1 scans two or more. BSS, then determines that they are in the overlapping area. After receiving the first request sending message, STA1 estimates the frequency offset according to the preamble of the first request sending message, and synchronizes its own transmitting end to the API, including Long Training Filed (LTF) and short training in the preamble. Field (Short Training Filed, STF for short), LTF is used for channel estimation, and STF is used for frequency offset estimation. The specific estimation method is prior art, so it will not be described here. STA1 compensates the estimated frequency offset to the crystal of the transmitting end, achieving frequency synchronization. Due to noise interference, the frequency offset through the preamble does not completely eliminate the frequency offset, and there is residual frequency offset. Although the residual frequency offset does not cause serious inter-carrier interference, over time, the data will be The OFDM symbol brings a phase offset. After the STA1 synchronizes its own transmitting end to the API, the identifiers of the scanned BSS1 and BSS2 and the number of scanned BSSs are carried in the first allowed sending message, and the API is determined according to the identification information of the first allowed sending message. When the initiator of the downlink channel is used, the first allowed transmission message is identified as corresponding to the initiator using the downlink channel, and the first allowed transmission message is broadcasted to the API and the AP2.

The first allowed to send the message may be specifically implemented by the following method. As shown in Table 1, the first allowed sending message includes: frame control information, occupied estimation time, number of scanned BSSs, all BSSIDs, and frame check sequences ( Frame Check Sequence, (FCS for short). The frame control information includes the IP address of the sending end, the IP address of the receiving end, and the like, and the estimated time is the time required to send the data to be sent. Specifically, the API carries the estimated estimated time in the first request sending message sent to the STA1. After receiving the first request message, the STA1 obtains the estimated time from the first request message and carries it in the first allowed sending message, and broadcasts it to each AP, so that other APs determine the downlink channel according to the estimated estimated duration. The release time, when the estimated time is up, the AP successfully sends the data and translates the downlink channel. The first allowed transmission message also carries the number of all BSSs scanned by STA1, and the BSSID of each BSS, and each BSSID is arranged in a certain order.

Table I The frame control occupies the pre-scanned all FCS information estimation time BSS number BSSID. Step 403: The API receives the first allowed transmission message sent by the STA1 broadcast, and determines the start time of sending the downlink data according to the first allowed transmission message.

In this embodiment, after receiving the first allowed sending message sent by the STA1, the API firstly identifies, according to the first allowed sending message, whether it corresponds to the initiator that uses the downlink channel, specifically, if the AP is in the first allowed to send the message. The corresponding BSS sequence is located in the first place, then it is determined that it corresponds to the initiator, and if it is not the first bit, it is determined that it does not correspond to the initiator.

When the API identification itself corresponds to the initiator, it is determined that the time for receiving the first permission to send the message is the start time, and the waiting time for transmitting the downlink data by itself is determined according to the first allowed transmission message. Specifically, the API acquires the duration T _RTS that the STA1 receives the first request sending message, and obtains the duration T _CTS that the STA1 sends the first allowed sending message according to the first request sending message; the API according to the number N of each BSS in the first allowed sending message, And the sequence number n itself in each BSS, and the waiting time is determined based on the following formula: T' = (Nn) xr - r _sra where = T _CTS + T _{RTS +} lx TT _SIFS is a short frame interval. The waiting time determined by the API according to the above formula is T+T _SIFS , and the time point after the API receives the first allowed transmission message and after the T+T _SIFS duration is determined as the starting time.

Step 404: The AP2 receives the first allowed sending message sent by the STA1 broadcast, and determines, according to the first allowed sending message, the starting time of sending the downlink data by itself.

In this embodiment, after receiving the first allowed sending message sent by the STA1, the AP2 parses and obtains the identifier of the BSS that carries the corresponding BSS in the first allowed sending message, and firstly estimates the frequency offset according to the preamble in the first allowed sending message. Synchronize its own transmitter to AP1. Then, the AP2 identifies that the first allowed transmission message corresponds to the initiator using the downlink channel according to the first permission to send message, and then identifies itself not corresponding to the initiator according to the order of the BSS corresponding to the first allowed transmission message.

The AP2 identifies that it does not correspond to the initiator, sends a second request sending message according to its corresponding BSS sequence, and receives the returned second allowed sending message, and takes the time of receiving the second allowed sending message as the starting time. Specifically, the AP2 calculates, according to the sequence number n in each BSS, the waiting duration T" required to send the second request sending information based on the following formula: "Ύ" = (η - 2) χ Τ ; where, = T _CTS + T _RTS + 2 x T _SIFS , 3⁄4IE is the short frame interval, T _RTS is to receive the first request transmission The duration of the message, the T _CTS is the length of time during which the first allowed message is sent according to the first request sent message. The waiting time for sending the second request sent by the AP2 is 0. Therefore, the AP2 sends a second request sending message directly to the STA2, where the second request sending message is used to indicate that the AP2 does not correspond to the initiator.

After receiving the second request sending message, the STA2 identifies that the AP2 does not correspond to the initiator, and then carries the scanned BSS1 and BSS2 in the second allowed sending message in order, and carries the number of BSSs in the second. In the allowed message transmission, the second allowed transmission message sent by the STA2 identifier does not correspond to the initiator using the downlink channel. STA2 also sends a second allowable send message to the API and AP2 broadcasts.

After receiving the second allowed sending message, the AP2 takes the time of receiving the second allowed sending message as the starting time, and determines the waiting time for sending the downlink data according to the first allowed sending message, and determining the waiting time may refer to the second embodiment. Describe, the waiting duration determined by AP2 is T _SIFS , so the total waiting duration determined by AP2 is the waiting time for sending the second request message plus the duration of sending the second request by AP2 and the duration of receiving the second request permission message, and adding The length of time required to send downstream data. Therefore, the total waiting time of AP2 is T+ T _SffS . That is, AP2 also starts to send data after waiting for T+T _SffS after receiving the first allowed transmission message. It can be seen from steps 402 and 403 that the start time determined by the API and AP2 is the same.

It can be understood that the steps 403 and 404 are not sequential, and are performed in parallel.

Step 405: AP 1 and AP 2 simultaneously transmit data when the start time expires.

It can be seen from steps 402 and 403 that the start time determined by the API and the AP2 is the same. After the STA2 sends the second allowed transmission message, the API and the AP2 reach the timing synchronization and the frequency synchronization. At this time, the API and the AP2 can simultaneously send the downlink. data. As shown in Figure 8, Figure 8 is a schematic diagram of two APs transmitting data at the same time.

Step 406: After receiving the data sent by the API and the AP2, the STA1 and the STA2 estimate the residual frequency offset according to the pilot carried in the downlink data, and eliminate interference by interference alignment.

Taking STA1 as an example to illustrate how to estimate the residual frequency offset according to the pilot, it is assumed that the API transmits the pilot ^^ and the sub-carriers respectively, and AP2 transmits the zero subcarrier at the sum, that is, AP2 does not transmit the carrier at the subcarrier and at the subcarrier. Then, STA1 receives the pilot at the sum, and ^F and 3⁄4 are represented by the following form:

Y^ ^ H^k ^ + n _ki = H { _x ) e~ ^k ^ x P _ki + n _ki Y _k2 W = /; _i (k ₂ )xP _k2 +n _k2 =H _n ( ₂ )xe~ ^k ^ xP _k2 + where the sum is the noise at the subcarriers ^ and respectively, referring to the channel matrix to STAI, ^123⁄4 Channel matrix of AP2 to STA1. 3⁄4 and , respectively, are the phase offset caused by the residual frequency offset and the sampling frequency offset.

shell'】

Because ^χν ^ρ ^ν £ ^Χ is a real number, Bell ' J

«! = ΖΥζ χ V _k[ = k _x e _x + φ _ι +ε _ι

«2 =ZY xV _k2 =^θ _ι +φ _ι +ε ₁

The sum is due to the error introduced by the noise, and the above two equations can be used to estimate ^θ \ and . In the same way, you can find the sum.

Based on the estimated phase offset, STA 1 eliminates the phase offset caused by the residual frequency offset and the sampling frequency offset. In the method provided by the embodiment, the receiving end STA synchronizes the frequency according to the preamble in the first allowed sending message according to the received first allowed sending message, and further determines the starting time of sending the data according to the first allowed sending message. Since the start times determined by the respective frames are the same, it is possible to ensure synchronization in time.

FIG. 9 is a schematic structural diagram of a 提供 provided by Embodiment 5 of the present invention. As shown in FIG. 9, the ΑΡ provided by the embodiment includes: a receiving module 51, a start time determining module 52, and a sending module 53.

The receiving module 51 is configured to receive a first allowed sending message sent by the STA, where the first allowed sending message includes an identifier of all basic service sets BSS that cover the STA.

In this embodiment, the STA is located in an overlapping area of multiple BSS coverage areas, and therefore, the STA can scan all BSSs covering itself. When the STA broadcasts the first allowable sending message, the APs of the BSSs can receive the first allowed sending message, and the first allowed message carries the identifiers of all the BSSs that cover the STA. BSSID. The BSSID can be the MAC address of the AP or other identifiers. Since the BSS corresponds to the AP, the identity of the BSS can determine the AP. Before the AP needs to send downlink data to the STA that it serves, the AP sends a request to send the message RTS to the STA. After receiving the CTS message returned by the STA, the AP can send data. In this step, the first CTS received by the AP may be the CTS that is triggered by the RTS being sent by itself, or may be triggered by the STA after the other AP sends the RTS. The start time determining module 52 is configured to determine, according to the first allowed sending message received by the receiving module 51, a start time of the downlink data sent by the access point AP, so that the start time determined by the AP and other BSSs in the first allowed sending message The AP determines the same start time.

The sending module 53 starts to send downlink data at the determined start time.

The sending module 53 determines the start time determined by the module 52 based on the start time, and starts transmitting downlink data when the start time expires. The APs in this embodiment can be used to perform the method shown in Figure 1. The method and technical effects are similar. You can refer to the description in the first embodiment. Let me repeat.

In the AP provided in this embodiment, when the AP has downlink data to be sent, all APs that receive the STA broadcast and send the first allowable sending message determine the start time of the sent data according to the received first allowed sending message, when the start When the time is up, the data is sent, and the start time determined by each AP is the same, so that each AP can synchronously transmit data, and the mutual interference generated when each AP in the overlapping area is out of synchronization is avoided.

FIG. 10 is a schematic structural diagram of an AP according to Embodiment 6 of the present invention. As shown in FIG. 10, the AP provided in this embodiment includes:

The receiving module 61 is configured to receive a first allowed sending message sent by the STA, where the first allowed sending message includes an identifier of all basic service sets BSS that cover the STA.

The start time determining module 62 is configured to determine, according to the first allowed sending message, a start time that the access point AP sends the downlink data, so that the start time determined by the AP and the start determined by the AP of the other BSS in the first allowed sending message The time is the same.

The sending module 63 starts to send downlink data at the determined start time.

In this embodiment, the start time determining module 62 includes: a sequence determining unit 621 and a time determining unit 622.

The sequence determining unit 621 is configured to determine an order of the BSS corresponding to the AP in the first allowed to send the message. The sequence determining unit 621 determines, according to the first allowed sending message received by the receiving module 61, the order of the BSS corresponding to the AP in the first allowed sending message, where the first allowed sending message carries the identifier of each BSS, and each identifier is determined according to a certain Arranged in order.

The time determining unit 622 is configured to determine the starting time and the waiting time according to the order, and determine the starting time according to the starting time and the waiting time.

In this implementation, when the AP receives the first permission to send a message, it also needs to identify whether it is Corresponding to and using the initiator of the downlink channel. If the AP identifies itself and the initiator, it is determined that the time for receiving the first allowed to send the message is the starting time, and determining the waiting time for sending the downlink data according to the first allowed sending message. The time determining unit 622 determines that the waiting time for the AP to send the downlink data according to the first permission sending message is: first, the time length T _{RTS at} which the STA receives the first request sending message, and the STA sends the first allowed sending message according to the first request sending message. The duration T _CTS , then, based on the number N of BSSs in the first allowed transmission message, and the sequence number n of the AP in each BSS, the waiting time is determined based on the following formula: Ύ ' = N - n T + T _SIFS , where , T = T _CTS + T _RTS + 2 T _slFS , T _SIFS is a short frame interval. The AP determines the start time according to the start time and the waiting time. For example, refer to the second embodiment.

If the AP identifies the non-correspondence and the initiator, the second request sending message is sent according to the sequence, and the returned second allowed sending message is received, and the time for receiving the second allowed sending message is used as the starting time, and the message is sent according to the first permission. Determine the waiting time for sending downlink data. The second request sending message is used to indicate that the AP does not use the initiator of the downlink channel, to indicate that the second allowed sending message sent by the STA identifier does not correspond to the initiator that uses the downlink channel. The time determining unit 622 sends the second request sending message according to the sequence: according to the sequence number n of the AP in each BSS, calculating the waiting time required to send the second request sending information according to the following formula: Ύ "

T _CTS + T _RTS + 2 x T _SIFS , T _SIFS is a short frame interval, T _RTS is a duration for transmitting a message by receiving the first request, and T _CTS is a duration for transmitting a first allowed transmission message according to the first request sending message. The AP determines the start time according to the start time and the waiting time. The AP may further include a channel identification module 64 for identifying whether the downlink channel to be used is idle when the AP needs to send downlink data. The channel identification module 64 identifies whether the downlink channel to be used is idle before the receiving module 61 receives the first allowed transmission message sent by the STA broadcast. Specifically, when the AP needs to send the downlink data, the channel identification module 64 determines whether the first allowed transmission message corresponding to the downlink channel to be used is received; if yes, determines that the downlink channel is not idle, and sends the message according to the first permission. The estimated occupancy time of the carried, and the translation time of the downlink channel is determined. If not, it is determined that the downlink channel is idle.

If the channel identification module 64 identifies that the downlink channel is idle, sending, to the STA that is to send the downlink data, a first request sending message indicating that the AP is the initiator that uses the downlink channel, to indicate that the first allowed sending message sent by the STA identifier corresponds to the use. The initiator of the downstream channel. If the channel identification module 64 identifies that the downlink channel is not idle, it determines that the bearer is carried according to the first allowed message. Use the estimated time to determine the release time of the downlink channel.

The AP provided in this embodiment can be used to perform the solution provided in Embodiment 1 and Embodiment 2 of the present invention. The implementation method and technical effects are similar, and details are not described herein again.

FIG. 11 is a schematic structural diagram of a STA according to Embodiment 7 of the present invention. The STA provided in this embodiment includes: a request sending message receiving module 71, a sending module 72, and a data receiving module 73.

The request sending message receiving module 71 is configured to receive a request sending message sent by the AP.

The sending module 72 is configured to send, according to the request to send a message, an identifier of the basic message set BSS that covers the STA, and send an allow message to the AP, to indicate that the AP is allowed according to the The sending message determines the start time of sending the downlink data, where the start time determined by the AP corresponding to each BSS in the allowed message is the same.

The data receiving module 73 is configured to receive downlink data according to the determined start time.

The STA provided in this embodiment is used to implement the technical solution provided by the implementation of the third embodiment, and the implementation method and the technical effect are similar, so no further details are provided herein.

FIG. 12 is a schematic structural diagram of a STA according to Embodiment 8 of the present invention, which is provided by this embodiment.

The STA includes: a request sending message receiving module 81, a message identifying module 82, a sending module 83, and a data receiving module 84.

The request sending message receiving module 81 is configured to receive a request sending message sent by the AP.

The message identification module 82 is configured to identify, according to the sending request message, whether the sender is sent by using an initiator of the downlink channel. If yes, the sending module 83 carries the identifier of all the BSSs that cover the STA in the permission to send message, and identifies that the allowed sending message corresponds to the initiator that uses the downlink channel; If not, the sending module 83 carries the identifier of all BSSs covering the STA in the permission to send message, and identifies that the allowed sending message does not correspond to the initiator using the downlink channel.

The sending module 83 is configured to send a message according to the request to generate an allow message to be sent, and allow the sending message to carry an identifier of all basic service sets BSS covering the STA, and send an allow message to the AP, to indicate that the AP determines to send the downlink data according to the allowed message. The start time, where the AP corresponding to each BSS in the allowed message is determined to have the same start time.

The data receiving module 84 is configured to receive downlink data according to the determined start time.

In this embodiment, the transmitting module 83 includes an information generating unit 831 and an information transmitting unit 832. The information generating unit 831 is configured to carry the identifiers of the APs corresponding to all the BSSs of the STAs in the allowable sending message, and carry the number of all the BSSs. The information sending unit 832 is configured to send the permission to send the message. The STA can send downlink data to each AP in a broadcast manner.

Further, in this embodiment, the scanning module 85 is further configured to scan all the BSSs covering the STA and record when the STA accesses the network and when the physical location changes. When the STA receives the request to send the message sent by the AP, according to all the BSSs scanned by the scanning module 85, the identifiers of all the BSSs that cover the STA are sequentially carried in the permission to send message.

The STAs provided in this embodiment are used to implement the technical solutions provided in the foregoing Embodiments 3 and 4, and the implementation methods and technical effects are similar, and details are not described herein again.

FIG. 13 is a schematic structural diagram of an AP according to Embodiment 9 of the present invention. As shown in FIG. 13, the AP 90 provided in this embodiment includes:

Receiver 91, processor 92, memory 93 and transmitter 94. The receiver 91, the memory 93, and the transmitter 94 can be connected to the processor 92 via a bus or other means, respectively, and the bus connection is taken as an example in FIG. The memory 93 is used to store executable program code, which includes computer operating instructions. The processor 92 runs an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus, or an Extended Industry Standard Architecture (abbreviated as an Extended Industry Standard Architecture). For EISA) bus etc. The bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in Figure 13, but it does not mean that there is only one bus or one type of bus.

The receiver 91 is configured to receive a first allowed sending message sent by the station STA, where the first allowed sending message includes an identifier of all basic service sets BSS covering the STA. The BSS identifier may be the MAC address of the AP, and may be other identifiers as long as it can uniquely identify one BSS.

The processor 92 is configured to determine, according to the first allowed sending message, a start time for the AP to send downlink data, so that the start time determined by the AP is the same as the start time determined by the APs of other BSSs in the first allowed sending message.

The transmitter 94 is configured to start sending downlink data at a determined start time.

The processor 92 is specifically configured to determine, according to the first allowed sending message received by the receiver 91, the order of the BSS corresponding to the AP in the first allowed sending message, and determine the starting time and the waiting time according to the sequence, according to the starting time and The waiting time determines the start time.

First, the processor 92 identifies, according to the first allowable sending message, whether the AP corresponds to the initiator that uses the downlink channel; if yes, determines that the time for receiving the first allowed to send the message is the starting time, and determines that the sending is downlink according to the first allowed sending message. The waiting time for data. The determining, by the processor 92, the waiting time for the AP to send the downlink data according to the first allowed sending message is: first, acquiring the duration T _RTS that the STA receives the first request sending message, and acquiring the sending, by the STA, the first allowed sending message according to the first request sending message. Duration T _CTS ; Then, according to the number N of BSSs in the first allowed transmission message, and the sequence number n of the AP in each BSS, the waiting time is determined based on the following formula:

T' = (N - n) x T + T _SIFS

Where = T _{CTS +} T _{RTS +} 2 x T _srFS , T _SIFS is the short frame interval.

In this embodiment, the processor 92 is specifically configured to: parse the time length T _RTS that the STA receives the first request sending message from the first allowed sending message, and obtain the duration T of the STA sending the first allowed sending message according to the first request sending message. _CTS .

If not, that is, the AP does not correspond to the initiator that uses the downlink channel, the processor 92 controls the transmitter 94 to send the second request to send the message according to the sequence, and receives the returned second allowed transmission message through the receiver 91, and receives the second. The time when the message is allowed to be sent is used as the starting time, and the waiting time for the AP to send the downlink data is determined according to the first allowed sending message, where the second request sending message is used to indicate that the AP does not use the initiator of the downlink channel, to indicate that the STA identifies the sending The second allowed to send message does not correspond to the initiator using the downlink channel. In this embodiment, the sending, by the processor 92, the second request sending message according to the sequence specifically includes: calculating, according to the sequence number n of each AP in each BSS, a waiting duration T" required to send the second request sending information according to the following formula: "

Where Ί = T _CTS + T _RTS + 2 x T _SIFS , T _SffS is a short frame interval, T _RTS is a duration for receiving a first request to send a message, and T _CTS is a message for transmitting a first allowed transmission message according to the first request sending message duration. The processor 92 is further configured to: when the AP needs to send the downlink data, identify whether the downlink channel to be used is idle; if the downlink channel is determined to be idle, send, by the transmitter 94, the STA that is to send the downlink data, indicating that the AP is using the downlink channel. The initiator's first request sends a message to indicate that the first allowed transmission message sent by the STA identity corresponds to the initiator using the downlink channel. The processor 92 determines, by the following manner, that when the AP needs to send downlink data, it is determined whether a first allowed transmission message corresponding to the downlink channel to be used is received; if yes, determining that the downlink channel is not idle, and according to the first The estimated estimated time of the downlink channel is allowed to be sent, and the downlink channel is determined to be released; if not, the downlink channel is determined to be idle.

FIG. 14 is a schematic structural diagram of a STA according to Embodiment 10 of the present invention. As shown in FIG. 14, the STA 100 provided in this embodiment includes:

Receiver 1000, processor 1001, memory 1002, and transmitter 1003. The receiver 1000, the memory 1002, and the transmitter 1003 may be respectively connected to the processor 1001 through a bus or the like, and the bus connection is taken as an example in FIG. The memory 1002 is configured to store executable program code, the program code including computer operating instructions. The processor 1001 passes the method. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in Figure 14, but it does not mean that there is only one bus or one type of bus.

The receiver 1000 is configured to receive a request sending message sent by the access point AP.

The processor 1001 is configured to send a message according to the request to generate an allow message to be sent, and allow the identifier of the basic service set BSS of the coverage site STA to be carried in the message.

The transmitter 1003 sends an allow message to the AP to instruct the AP to determine, according to the allowed message, a start time for sending the downlink data, where the start time determined by the AP corresponding to each BSS in the allowed message is the same.

The receiver 1000 is further configured to receive downlink data according to the determined start time.

The processor 1001 is specifically configured to press, according to the identifier of the AP corresponding to all BSSs of the STA. The sequence is carried in the message that is allowed to be sent, and carries the number of all BSSs, and generates an allow message to be sent. The transmitter 1003 is configured to send the permission to send a message.

In this embodiment, the processor 1001 is further configured to scan all BSSs covering the STA when the STA accesses the network and when the physical location changes, and record and save the data to the memory 1002.

In this embodiment, the processor 1001 is further configured to: according to the sending request message received by the receiver 1000, whether the identifier is sent by the initiator of the downlink channel; if yes, the identifier of all the BSSs of the coverage STA is carried in the permission to send message, And identifying the allowed message to be sent corresponds to the initiator using the downlink channel. If not, the sending module carries the identifier of all BSSs covering the STA in the allowable sending message, and identifies that the allowed sending message does not correspond to the initiator using the downlink channel.

One of ordinary skill in the art will appreciate that all or part of the steps to implement the various method embodiments described above can be accomplished by hardware associated with the program instructions. The aforementioned program can be stored in a computer readable storage medium. The program, when executed, performs the steps including the above-described method embodiments; and the foregoing storage medium includes: a medium that can store program codes, such as a ROM, a RAM, a magnetic disk, or an optical disk.

It should be noted that the above embodiments are merely illustrative of the technical solutions of the present invention, and are not intended to be limiting; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art The technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and the modifications or substitutions do not deviate from the technical solutions of the embodiments of the present invention. range.

Claims

Rights request

1. A downlink data sending method, characterized by including:

The access point AP receives the first permission to send message sent by the station STA, wherein the first permission to send message includes identifiers of all basic service sets BSS covering the STA;

The AP determines the starting time for the AP to send downlink data based on the first allowed to send message, so that the starting time determined by the AP is consistent with the starting time determined by the APs of other BSSs in the first allowed to send message. same;

2. The method according to claim 1, wherein the AP determines the starting time for the AP to send downlink data based on the first allowed sending message, including:

The AP determines the order of its corresponding BSS in the first permission to send message; the AP determines the starting time and waiting time based on the order, and determines the starting time based on the starting time and waiting time.

3. The method according to claim 2, characterized in that, before the AP receives the first permission to send message sent by the STA, it further includes:

When the AP needs to send downlink data, it identifies whether the downlink channel to be used is idle; if the AP identifies that the downlink channel is idle, it sends a signal to the STA to be sent downlink data indicating that the AP is using the downlink channel. The first request-to-send message of the initiator indicates that the first allow-to-send message sent by the STA identification corresponds to the initiator using the downlink channel.

4. The method according to claim 3, wherein when the AP needs to send downlink data, identifying whether the downlink channel to be used is idle includes:

When the AP needs to send downlink data, it determines whether it has received the first permission to send message corresponding to the downlink channel to be used;

If so, determine that the downlink channel is not idle, and determine the interpretation time of the downlink channel based on the estimated occupancy time carried in the first permission to send message;

If not, it is determined that the downlink channel is idle.

5. The method according to claim 3, wherein the AP determines the starting time and waiting time according to the sequence including:

The AP identifies, according to the first permission to send message, whether it corresponds to using the next The initiator of the walking channel;

If so, the AP determines that the time of receiving the first permission to send message is the starting time, and determines the waiting time for itself to send downlink data based on the first permission to send message;

If not, the AP sends a second request to send message according to the sequence, and receives the returned second permission to send message, using the time when the second permission to send message is received as the starting time, and based on the first permission Send a message to determine the waiting time for sending downlink data, wherein the second request to send message is used to indicate that the AP is not the initiator of using the downlink channel, and to indicate that the second allow to send message sent by the STA identification is not Corresponds to the initiator using the downlink channel.

6. The method according to claim 5, wherein the AP determines the waiting time for sending downlink data based on the first allowed sending message, including:

The AP acquires the duration T _RTS for the STA to receive the first request to send message, and acquires the duration T _CTS for the STA to send the first permission to send message according to the first request to send message; 1. The number N of each BSS in the message that is allowed to be sent, and its own sequence number n in each BSS, determine the waiting time based on the following formula:

Ύ' - (N - n) x T + T _SIFS

Among them, = T _{CTS +} T _{RTS +} 2 x T _srFS , T _SIFS is the short frame interval.

7. The method according to claim 6, wherein the AP sending the second request to send message according to the sequence includes:

The AP calculates the waiting time T required to send the second request to send information based on its own sequence number n in each BSS based on the following formula:

Among them, = T _CTS + T _RTS + 2 x TT _SffS is the short frame interval, T _RTS is the duration of receiving the first request to send message, and T _CTS is the first permission to send according to the first request to send message. The duration of the message.

8. The method according to claim 7, characterized in that, the AP obtains the duration _TRTS for the STA to receive the first request to send message, and obtains the time period for the STA to send the first request to send message according to the first request to send message. The time period T _CTS allowed to send messages includes:

The AP parses and obtains the duration _TRTS for the STA to receive the first request to send message from the first permission to send message, and obtains the duration for the STA to send the first permission to send message according to the first request to send message. T _CTS .

9. The method according to any one of claims 1 to 8, characterized in that: the BSS identifier is

AP's MAC address.

10. A downlink data receiving method, characterized by including:

The site STA receives the request to send message sent by the access point AP;

The STA generates a permission to send message based on the request to send message, the permission to send message carries the identification of all basic service sets BSS covering the STA, and sends the permission to send message to the AP to indicate that the The AP determines the starting time for sending downlink data based on the allow to send message, where the start time determined by the AP corresponding to each BSS in the allow to send message is the same;

The STA receives downlink data according to the determined starting time.

11. The method according to claim 10, characterized in that, the STA generates a permission to send message based on the request to send message, and the permission to send message carries the identification of all basic service sets BSS covering itself, and sends it to the STA. The AP sending the allow to send message includes:

The STA carries the identifiers of the APs corresponding to all BSSs covering itself in the allow-to-send message in order, and carries the number of all BSSs;

The STA sends the allow to send message.

12. The method according to claim 10, further comprising:

When the STA accesses the network and changes its physical location, it scans all the BSS covering itself and records them.

13. The method according to any one of claims 10 to 12, characterized in that, the STA generates a permission to send message according to the request to send message, and the permission to send message carries the identifiers of all basic service sets BSS covering itself. , and sending the allow to send message to the AP includes:

The STA identifies whether the sending request message is sent by the initiator using the downlink channel;

If so, the STA carries the identifiers of all BSSs covering itself in the allow-to-send message, and identifies that the allow-to-send message corresponds to the initiator using the downlink channel;

If not, the STA carries the identifiers of all BSSs covering itself in the allow-to-send message, and identifies that the allow-to-send message does not correspond to the initiator using the downlink channel;

The STA broadcasts the permission to send message.

14. An access point AP, characterized by including: A receiving module, configured to receive a first allowed-to-send message sent by the site STA, wherein the first allowed-to-send message includes identifiers of all basic service sets BSS covering the STA; A start time determination module, configured to determine according to the The first permission to send message determines the starting time for the AP to send downlink data, so that the starting time determined by the AP is the same as the starting time determined by the APs of other BSSs in the first permission to send message;

The sending module is used to start sending downlink data at the determined starting time.

15. The AP according to claim 14, characterized in that the starting time determination module includes:

A sequence determining unit, used to determine the sequence of the BSS corresponding to the AP in the first permission to send message;

A time determination unit, configured to determine the starting time and the waiting time according to the sequence, and determine the starting time based on the starting time and the waiting time.

16. The AP according to claim 15, further comprising:

A channel identification module, used to identify whether the downlink channel to be used is idle when the AP needs to send downlink data;

If the AP recognizes that the downlink channel is idle, it sends a first request to send message to the STA to be sent downlink data indicating that the AP is the initiator of using the downlink channel to indicate that the STA identifies the first sender. A permission to send message corresponds to the initiator using the downlink channel.

17. The AP according to claim 16, characterized in that the channel identification module is specifically used to:

When the AP needs to send downlink data, determine whether it has received the first permission to send message corresponding to the downlink channel to be used;

If not, it is determined that the downlink channel is idle.

18. The AP according to claim 16, characterized in that the time determination unit is specifically used to:

Identify whether the AP corresponds to the initiator using the downlink channel according to the first permission to send message;

If so, then determine the time when the first permission to send message is received as the starting time, and based on The first permission to send message determines the waiting time for itself to send downlink data;

If not, then send the second request to send message according to the sequence, and receive the returned second permission to send message, use the time when the second permission to send message is received as the starting time, and determine based on the first permission to send message The waiting time for the AP to send downlink data, where the second request to send message is used to indicate that the AP is not the initiator of using the downlink channel, to indicate that the second allow to send message sent by the STA identification does not correspond to the initiator using the downlink channel.

19. The AP according to claim 18, wherein the time determination unit determines the waiting time for the AP to send downlink data according to the first permission to send message including: obtaining the STA to receive the first request to send message. The duration T _RTS is to obtain the duration T _CTS for the STA to send the first permission to send message according to the first request to send message;

According to the number N of each BSS in the first permission to send message and the sequence number n of the AP in each BSS, the waiting time is determined based on the following formula:

Ύ' -(Nn)xT + T _SIFS

Among them, T = r _CTS + r _ra +2xr _sra , T _SIFS is the short frame interval.

20. The AP according to claim 19, wherein the time determination unit sending the second request to send message according to the sequence includes:

According to the sequence number n of the AP in each BSS, the waiting time T" required to send the second request to send information is calculated based on the following formula:

Wherein, T = T _CTS + T _RTS + 2xT _SIFS , T _SffS is the short frame interval, T _RTS is the duration of receiving the first request to send message, T _CTS is the time to send the first request to send message according to the first request to send message. The length of time allowed for sending messages.

21. The AP according to claim 20, characterized in that: obtaining the duration T _RTS for the STA to receive the first request to send message, and obtaining the first permission for the STA to send the first request to send message according to the first request to send message. The length of time T _CTS for sending a message includes:

The time period T _RTS for the STA to receive the first request to send message is obtained by parsing the first permission to send message, and the time period _TCTS for the STA to send the first permission to send message according to the first request to send message is obtained.

22. The AP according to any one of claims 14 to 21, characterized in that: the BSS identifier is the MAC address of the AP.

23. A site STA, which is characterized by including:

A request-to-send message receiving module, configured to receive a request-to-send message sent by the access point AP; and a sending module, configured to generate a permission-to-send message based on the request-to-send message, where the permission-to-send message carries all basic information covering the site STA. The identification of the service set BSS, and sends the allow to send message to the AP to instruct the AP to determine the starting time for sending downlink data based on the allow to send message, where, the AP of each BSS in the allow to send message The determined starting time is the same;

The data receiving module is used to receive downlink data according to the determined starting time.

24. The STA according to claim 23, characterized in that, the sending module includes: an information generation unit, carrying the identifiers of APs covering all BSSs of the STA in the allow to send message in order, and carrying The number of all BSS;

An information sending unit, configured to send the permission to send message.

25. The STA according to claim 23, further comprising:

The scanning module is used to scan all BSSs covering the STA when the STA accesses the network and when the physical location changes, and records them.

26. The STA according to any one of claims 23 to 25, further comprising: a message identification module, configured to identify whether the transmission request message is sent by the initiator using the downlink channel;

If yes, then the sending module carries the identifiers of all BSSs covering the STA in the allow to send message, and identifies that the allow to send message corresponds to the initiator using the downlink channel; if not, then the sending module Carrying the identities of all BSSs covering the STA in the allow-to-send message, and identifying that the allow-to-send message does not correspond to the initiator using the downlink channel;

The sending module sends the permission to send message.