WO2013104332A1

WO2013104332A1 - Method and station for requesting using midamble in data transmission

Info

Publication number: WO2013104332A1
Application number: PCT/CN2013/070369
Authority: WO
Inventors: 黄永明; 李世党; 杨讯
Original assignee: 华为技术有限公司
Priority date: 2012-01-11
Filing date: 2013-01-11
Publication date: 2013-07-18
Also published as: CN103209043A; CN103209043B

Abstract

Disclosed is a method for transmitting data in a wireless local area network, comprising a receiving end generates a very high throughput (VHT) control frame, wherein in the VHT control frame, a bit indicating the type of the frame format and a bit in the field indicating the number of space time stream form a binary information bit group; the VHT control frame is transmitted to a transmitting end, wherein the binary information bit group in the VHT control frame is used for requesting the transmitting end to use midamble in data transmission, so that the transmitting end inserts a long training field to the data transmitted to the receiving end.

Description

Method and site for requesting use of midamble in data transmission

The present invention relates to the field of communications, and in particular, to a method for requesting mid-range (Doppler/Midamble) feedback in a wireless local area network. Background technique

In order to extend WLAN technology to cover a wider range of applications, such as its coverage from 100m to lKm, it is necessary to re-examine and correct existing WLAN technologies. Correspondingly, the application scenario is no longer limited to indoors, but can be applied to an outdoor environment. The outdoor environment is more complicated than the indoor environment. One important factor is that there are a large number of moving objects in the outdoor environment, and the mobility of the objects causes instability and rapid fading of the wireless channel. Fast fading can greatly shorten the time that a channel is considered static or constant. The easiest way to deal with this effect is to limit the length of time each packet is sent to less than the channel change.

The Doppler/Midamble scheme is introduced under the influence of the Doppler effect. In some cases, the rapid change of the channel causes the channel in the data duration to be different from the channel measured by the packet header, affecting the latter part of the packet. Correct acceptance and demodulation decoding. In order to solve such problems without affecting the packet length, it is necessary to insert a Midamble at regular intervals during data transmission. Introducing Doppler/Midamble, the essence is to insert two LTFs and one STF in the subsequent data part. However, in the prior art, there is no information on how to feed back the period of STF/LTFs and how to set the period of feedback bits. Get a good solution. Summary of the invention

Embodiments of the present invention provide a method and apparatus for feeding back periods of STF/LTFs and setting period information of feedback bits.

A method for requesting a midamble (Doppler/Midamble) in data transmission, comprising: a receiving end generating a VHT control frame, wherein a bit for a frame format type indication in the VHT control frame and indicating a number of space-time streams One bit in the field constitutes a binary information bit group; the VHT control frame is sent to the transmitting end, and the binary information bit group in the VHT control frame is used to request the transmitting end to use in data transmission. The pilot code causes the transmitting end to insert a long training field into the data sent by the receiving end. Another method for requesting a midamble (Doppler/Midamble) in data transmission includes: a receiving end generates a VHT control frame, and two of the high-order bits of the VHT control frame are 25-27 bits (B24-B26) The bits form a binary information bit group, and the binary information bit group is used to feed back to the transmitting end (Doppler/Midamble) information;

Sending the VHT control frame to the sending end, where the binary information bit group in the VHT control frame is used to request the transmitting end to use a midamble code in data transmission, so that the sending end sends the sending end to the receiving end Insert a long training field into the data.

Further, the embodiment of the present invention further provides an apparatus for implementing the foregoing method, which may be an access point AP or a station STA in a wireless local area network. In practice, the AP and the STA may exchange roles.

A site STA, including:

a frame generating unit, configured to generate a VHT control frame, where a bit in the VHT control frame for the frame format type indication and one bit in the field indicating the number of space-time streams constitute a binary information bit group, the VHT control The binary information bit group in the frame is used to request the transmitting end to use the midamble code in the data transmission, so that the sending end inserts a long training field into the data sent by the receiving end;

And a sending unit, configured to send the VHT control frame to the sending end.

Another site STA, including:

a frame generating unit, configured to generate a VHT control frame, where two bits of the 25th to 27th bits (B24-B26) in the upper part of the VHT control frame constitute a binary information bit group, where the VHT control frame is The binary information bit group is used to request the transmitting end to use the midamble in the data transmission, so that the long end training field is inserted into the data sent by the sending end to the receiving end;

And a sending unit, configured to send the VHT control frame to the sending end. Requested on-going (Doppler/Midamble) feedback is implemented on the basis of the structure. DRAWINGS

FIG. 1 is a schematic structural diagram of a high throughput control frame according to an embodiment of the present invention.

2 is a schematic structural diagram of a VHT control field (B1-B29) according to an embodiment of the present invention.

Fig. 3 is a schematic view showing the structure of an MFB (B9-B23) according to an embodiment of the present invention.

4 is a schematic structural diagram of a basic block confirmation frame according to an embodiment of the present invention.

FIG. 5 is a schematic structural diagram of a BA control field according to an embodiment of the present invention. FIG. 6 is a schematic structural diagram of GID-H when requesting MFB according to an embodiment of the present invention.

FIG. 7 is a schematic structural diagram of an HT control field according to an embodiment of the present invention.

Figure 8 is a flow chart of a method in accordance with an embodiment of the present invention.

9 is a flow chart of another method of an embodiment of the present invention. detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described in the following with reference to the accompanying drawings in the embodiments.

The embodiment of the present invention may be that data transmission is being performed between a station (STA) and an access point (AP, Access Point) in the WLAN. Sometimes the AP can be considered a special site. It can be considered that the station (STA) and the access point are the sender and receiver of each other. Therefore, in the following embodiments, the device may be a STA or an AP, and the system may be a WLAN composed of a station (STA) and an access point (AP, Access Point).

The embodiment of the present invention mainly provides a bit indication method for Doppler/Midamble feedback. Doppler/Midamble is due to the need to insert some information similar to the preamble preamble in the middle of the data due to the Doppler effect.

With the technical solution of WLAN, the network throughput is continuously improved, and HT (High Throughput) and VHT (Very High Throughput) technologies have emerged. Referring to FIG. 1, a schematic diagram of a high-throughput control frame in a current wireless standard according to an embodiment of the present invention, wherein a VHT field and a frame format type indication bit, (B0) are used to identify whether the current transmission is a VHT format or an HT format, and further includes a VHT control. Field (B1-B29), (field specific to the HT or VHT variant), AC Constraint is used to indicate whether the data is limited to one access type (AC) and RDG/MorePPDU when the reverse transmission (RDG) is indicated. Initiator, indicating whether to authorize RDG; if it is a Responder of RDG, indicating whether there is data behind it.

Further, the specific format of the VHT control field (B1-B29) is shown in FIG. 2. The control field includes: reserved bits (Reserved, Bl), and MRQ (B2) represents MCS request (Modulation and Coding Scheme, MCS, Request) The MSI/STBC (MRQ Sequence Identifier/STBC Indication) indication bit is used to indicate whether the data for the feedback frame is used by the STBC (STBC) when the sequence number (MSI) carried by the request is requested when the feedback is requested. MFSI/GID-L ( MFB Sequence Indentifier/LSB of Group ID ) indication When the bit is used to indicate the passive feedback MCS, the feedback corresponding to the feedback data carries the sequence number (MFSI) I Group ID low bit (LSB of Group ID), MFB (B9-B23) indicates MCS feedback (Modulation and Coding Scheme, MCS, Feedback), GID-H is the group ID (Group ID) high-order bit, coding type indicates the coding type of the MFB (Coding type of MFB response), and FB Tx Type indicates the data for the MFB. Transmission type of MFB response, Unsolicited MFB indicates active request feedback MFB.

Further, the specific format of MFB (B9-B23) is shown in Figure 3.

MFB is mainly used to indicate N-STS, MCS, BW and SNR feedback, where N-STS represents the number of Space Time Streams, MCS represents the modulation and coding scheme, BW represents the bandwidth, and SNR represents the signal-to-noise ratio. .

Further, with the development of wireless local area networks and the wide application scenarios, such as the application of intelligent networks, new requirements have been put forward for infinite local area networks. The latest protocol specifies that the receiving end can request a data frame with a midamble, and the VHT control field adds an ability to use the non-request feedback to cause the STA to request the frame format. In various embodiments of the invention, the receiving end sends (feedback) to the transmitting end for requesting the transmitting end to transmit information to the receiving end using the Doppler/Midamble frame.

If the maximum number of space-time streams supported in the protocol is 4, the indication of the number of space-time streams can be completed with two bits, so one bit can be saved in the N-STS field to indicate Doppler/Midamble, for example, B9 or B10. In addition, as described above, the B0 bit is used to indicate the format of the HT or the VHT. In the scenario where the VHT format is specifically transmitted, for example, in the embodiment of the present invention, the B0 bit is saved, that is, it can be used to indicate other information, because the system Both are sent in VHT format. Therefore, one bit of the available frame format type indication bit (B0) and N-STS fields constitutes a 2-bit information bit to indicate Doppler/Midamble feedback.

In the embodiment of the present invention, the method that the receiving end requests to use the midamble in the data transmission at the transmitting end may use the frame format type indication bit (B0) and one bit in the N-STS field to form 2 bits to indicate the request high. The Doppler frame format, such as B0B9=00 or B1B9=00, is used to indicate that the high Doppler frame format is requested;

The above 2 bits are still used to request the feedback of the Midamble period. See Table 1 below for the way to request the Midamble period: Table 1

In addition, it is also possible to perform periodic feedback in an equal step manner, for example, 01, 10, and 11 sequentially represent 30, 55, 80, and the like. Different values can be chosen according to practice. Here, the feedback value, for example, 30 refers to the number of OFDM symbols.

Further, after the system can support the multi-density Doppler/Midamble, the embodiment of the present invention also provides a basic Block Acknowledgement (BA) frame format and a BA control field format, where BA is continuously transmitted. Referring to FIG. 4, the basic Block Acknowledgement (BA) frame format, the BA frame includes a 2-bit frame control field, a 2-bit duration sub-segment, a 6-bit receiver MAC address RA, and a 6-bit transmitter MAC address. Address TA, 2-bit BA control field, 2-bit Revelation Sequence Control field, 8-bit or 128-bit block acknowledgment bitmap and 4-bit FCS.

Figure 5 shows the format of the BA control field, including: BA acknowledgment policy, multiple TID, compressed bitmap, compressed bitmap, TID/TID number and 4-12 bits (B3-B11) as reserved bits.

If the channel changes faster, the STA can calculate the channel change by receiving the data packet. At this time, the STA needs to request a high Doppler frame format, and informs the AP that the Doppler/Midamble interpolation period needs to be adjusted. The specific operations are as follows:

S201: The AP first sends the first frame data in a relatively dense Doppler/Midamble period. S203. When the STA considers that the Doppler/Midamble period with a relatively low density can be used to reduce the overhead, the AP may use a Reserved bit in the BA. Instructing the information, the AP receives the information and interpolates using a Doppler/Midamble period with a lower density.

The above situation is directed to the case of continuously transmitting an ACK, and the direction of the adjustment is adjusted from the most dense to the smallest. For the sake of implementation, a preset bit can be additionally used in the BA to indicate the adjustment information of the direction.

Further, the embodiment of the present invention provides another method for the receiver to request the use of the midamble in the data transmission at the transmitting end.

In the current agreement, it is possible to specify the Solicited MFB, GID-H (B24-B26) The three bits are reserved, so in the present embodiment, the portion is used to indicate the request high

The Doppler frame format and the interpolation of STF/LTFs are performed every other number of symbols. As shown in Figure 6, the format of GID-H is changed when MFB is requested, and the Midamble Request is performed with one bit, such as B24. The 2 bits indicate how many symbols are interpolated for STF/LTFs ( Recommend Midamble Interval).

In the present embodiment, the method of requesting Doppler/Midamble feedback sets the unsolicited MFB bit to 0, and then the FB is generated from the SU PPDU (here can support the requested FB and the unsolicited FB), in the GID-H The field selects one bit to indicate the requesting high Doppler frame format; the other 2 bits of the GID-H field indicate how many symbols to be fed back for STF/LTFs interpolation after the channel change, the specific classification is shown in Table 2. Show.

Table 2

A method for requesting the use of a midamble (Doppler/Midamble) in data transmission according to an embodiment of the present invention includes:

S10: The receiving end generates a VHT control frame, where a bit in the VHT control frame for the frame format type indication and one bit in the field indicating the number of space-time streams form a binary information bit group; S20, sending the VHT control to the sending end The frame, the binary information bit group in the VHT control frame is used to request the sender to use the midamble in the data transmission so that the sender sends a long training field to the data sent by the receiver.

As another embodiment, referring to FIG. 9, a method for requesting a medium code (Doppler/Midamble) in data transmission includes:

S30, the receiving end generates a VHT control frame, and two bits of the 25-27 bits (B24-B26) in the upper part of the VHT control frame form a binary information bit group, and the binary information bit group is used for feedback to the transmitting end. Guide code (Doppler/Midamble) information;

S40: Send a VHT control frame to the sending end, where the binary information bit group in the VHT control frame is used by the requesting sending end to use the middle guiding code in the data sending, so that the long training field is inserted into the data sent by the sending end to the receiving end.

The previous embodiment describes the method in the VHT format, and the following gives an example. An embodiment of the HT format. As shown in Figure 7, the HT control field is controlled by link adaptation.

(B1-B15), Calibration Position (B16-B17), Calibration Sequence (B18-B19), Reserved (B20-B21), CSI/Control (B23-B24), NDP Notice (B24), Reserved (B25-B28) , DEI (B29) composition. The embodiment of the present invention uses the reserved bits of the HT format (4 bits, B20-B21) to indicate the request for the high Doppler frame format and the Midamble interpolation period to be fed back.

In this embodiment, the method for requesting Doppler/Midamble feedback uses one of the reserved bits, such as B25, to indicate that the high Doppler frame format is requested; with another three bits,

(B26B27B28) Instructs the STA to feed back to the AP to adjust the Midamble interpolation period. The following table gives a specific example:

Further, a new embodiment is given. In the actual wireless local area network protocol, the data field is composed of a service field, a data bit, a tail bit, and a padding bit, wherein the padding bit is selected and added as needed. The first sixteen bit service fields of the data field. The first seven bits of the service field are the initialization bits of the scrambler for synchronization with the descrambler. These bits are set to 0 to estimate the initial state of the scrambler in the receiver. In addition, the first seven bits are pseudo-random integers. In the embodiment of the present invention, any two bits of the seven bits representing the pseudo-random integer are used to indicate that the high Doppler frame format is requested and the Doppler/Midamble is fed back. The essence of the scheme does not affect the generation of pseudo-random sequences. In this embodiment, a method for requesting Doppler/Midamble feedback is sent, and an HT format frame is sent, where B0B1=00 is set to indicate that Doppler/Midamble is not required to be fed back; when B0B1=01, 10 or 11 is set, the number of feedbacks is required. The symbols are inserted into the STF/LTFs, and the specific correspondence may be similar to the contents of the table of the first embodiment.

In the embodiment of the present invention, the transmitting end and the receiving end use the method in the foregoing method embodiment to perform communication, and the transmitting end and the receiving end can complete the foregoing method and each process, so when introducing the transmitting end and the receiving end in the system, See the method embodiment for the method. Each function module or unit or device such as a processor in the device can respectively implement the functions and operations of the above methods. The AP can completely perform the above method as an execution subject of the above method.

The embodiment of the present invention provides a site STA, which may also be an AP, because the AP may be considered as a special STA, and the site includes: a frame generating unit, configured to generate a VHT control frame, where one bit in the VHT control frame for the frame format type indication and one bit in the field indicating the number of space-time streams constitute a binary information bit group, and the second in the VHT control frame The meta information bit group is used to request the transmitting end to use the midamble code in the data transmission, so that the long end training field is inserted into the data sent by the sending end to the receiving end;

And a sending unit, configured to send a VHT control frame to the sending end.

Another site STA, the site includes:

a frame generating unit, configured to generate a VHT control frame, where two bits of the 25-27 bits (B24-B26) in the VHT control frame form a binary information bit group, and the binary information bit group in the VHT control frame is used. The requesting sender uses the midamble in the data transmission to enable the sending end to insert a long training field into the data sent by the receiving end;

And a sending unit, configured to send a VHT control frame to the sending end.

A person skilled in the art can understand that all or part of the process of implementing the above embodiment method can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. In execution, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, or a read-only storage memory.

(Read-Only Memory, ROM) or Random Access Memory! RAM ( Random Access Memory, RAM).

Claims

Rights request

A method for requesting a use of a midamble (Doppler/Midamble) in data transmission, the method comprising:

The receiving end generates a VHT control frame, where one bit of the bit for the frame format type indication and one of the fields indicating the number of space-time streams in the VHT control frame constitutes a binary information bit group; and the sending the The VHT control frame, the binary information bit group in the VHT control frame is used to request the transmitting end to use the midamble in the data transmission, so that the long end training field is inserted into the data sent by the sending end to the receiving end.

2. The method according to claim 1, wherein the one bit for the frame format type indication is located at a first bit (B0) of the upper bit of the VHT control frame.

The method according to claim 1, wherein the field indicating the number of space-time streams is located in the 10th to 12th bits (B9-B11) of the VHT control frame.

A method for requesting the use of a midamble (Doppler/Midamble) in data transmission, characterized in that the method comprises:

The receiving end generates a VHT control frame, and the high-order bit in the VHT control frame is 25-27 bits.

The two bits of (B24-B26) form a binary information bit group, and the binary information bit group is used to feed back to the transmitting end (Doppler/Midamble) information;

5. A site STA, wherein the site comprises:

The station according to claim 5, wherein the one bit for the frame format type indication in the VHT control frame generated by the frame generating unit is located at the first bit of the VHT control frame high bit Bit (B0).

The station according to claim 5, wherein the frame generating unit generates The field indicating the number of space-time streams in the VHT control frame is located at the 10th to 12th bits (B9-B11) of the VHT control frame.

8. A site STA, wherein the site comprises: