CN103138870A - Data transmission method and data transmission device - Google Patents

Abstract

Embodiments of the present invention provide a data transmission method and a data transmission device. The method includes: generating a PPDU, the PPDU includes N groups of long training domains, wherein N is a positive integer and is determined by the number of space-time flows adopted by the PPDU, and each group of long training domains includes M long training domains, wherein M is a positive integer and for Different PPDUs are variable; send PPDUs to the receiving end. The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

Description

Data transmission method and data transmission device

technical field

The embodiments of the present invention relate to the field of wireless communication, and more specifically, to a data transmission method and a data transmission device.

Background technique

Basic Service Set (BSS) is a basic component of a wireless local area network (Wireless local area net, WLAN). Stations (STAs, Stations) within a certain coverage area and having certain associations form a BSS. The most basic form of association is that stations communicate directly with each other in an ad hoc network, which is called an independent basic service set (Independent BSS, IBSS).

A more common situation is that the STA is associated with a central site called an Access Point (AP) dedicated to managing the BSS. A BSS built around an AP is called a BSS with infrastructure. BSS with infrastructure can be connected to each other by their APs through a distributed system (Distributed System, DS) to form an extended BSS (Extend BSS, ESS).

OFDM (Orthogonal frequency-division multiplexing) is a method of dividing a high-speed data stream into several low-speed data streams, and simultaneously modulating these low-speed data streams on several mutually orthogonal carrier waves. Since the bandwidth of each subcarrier is smaller and closer to the coherent bandwidth, it can effectively resist frequency selective fading, so it is widely used in wireless communication today. OFDM belongs to the multi-carrier transmission technology. The so-called multi-carrier transmission technology refers to dividing the available frequency spectrum into multiple sub-carriers, and each sub-carrier can carry a low-speed data stream.

The physical layer frame structure specifies the functional division and time/frequency occupancy relationship of a data frame. The data frame can also be called PLCP (Physical Layer Convergence Procedure, physical layer convergence process) protocol data unit (PPDU, PLCP protocol data unit) or data unit. Taking a typical WLAN protocol as an example, its physical layer frame structure includes short training field (STF, short training field), long training field (LTF, long training field), control signaling (SIG, signal) and data. The STF may be a synchronization sequence, and the LTF may be a pilot.

In a typical receiving process, the synchronization time is first obtained through synchronization sequence detection, and then the control signaling is demodulated through pilot channel estimation, and finally through the pilot channel estimation and the message in the control signaling (including the modulation and coding adopted by the data) mode and the length of the data, etc.) to detect the data.

Specifically, the long training domain is mainly used for channel estimation. Due to the time-varying nature of the wireless channel and the frequency selectivity brought by multipath, each resource element (subcarrier) of the OFDM system has different fading conditions. In order to enable the receiving end to correctly estimate the fading situation, the transmitting end will transmit a pre-negotiated known signal such as a long training field, so that the receiving end can estimate the channel response.

In the 802.11 protocol, each frame has only one long training field, which is applicable to situations where the duration of a frame is relatively short (a few milliseconds at most), such as indoor scenarios where channel time domain changes slowly. However, the latest 802.11ah protocol requires a smaller bandwidth, and only supports a minimum bandwidth of 1MHz. At this time, for a data packet of the same size, at the same transmission rate, the transmission time will increase by dozens of times compared with before, reaching tens of milliseconds. At the same time, the 802.11ah protocol needs to support outdoor low-speed mobile application scenarios. In this scenario, the channel time domain changes faster than before, so the current frame structure will not be able to track channel changes well.

Contents of the invention

Embodiments of the present invention provide a data transmission method and a data transmission device, which can adapt to scenarios of low-speed data transmission.

On the one hand, a data transmission method is provided, including: generating a PPDU, the PPDU includes N long training domains, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each long training domain includes M long training domains field, where M is a positive integer and variable for different PPDUs; send PPDUs to the receiving end.

On the other hand, a data transmission method is provided, including: receiving a PPDU, the PPDU includes N group length training fields, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each group length training field includes M long A training domain, where M is a positive integer and variable for different PPDUs; use N groups of long training domains to perform channel estimation processing on PPDUs.

On the other hand, a data transmission device is provided, including: a generating unit, configured to generate a PPDU, the PPDU includes an N group length training field, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each group length training field The field includes M long training fields, where M is a positive integer and is variable for different PPDUs; the sending unit is used to send the PPDU generated by the generating unit to the receiving end.

On the other hand, a data transmission device is provided, including: a receiving unit, configured to receive a PPDU, the PPDU includes an N group leader training field, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each group leader training field The field includes M long training fields, where M is a positive integer and is variable for different PPDUs; the processing unit is used to perform channel estimation processing on the PPDU received by the receiving unit by using N groups of long training fields.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is a flowchart of a data transmission method according to an embodiment of the present invention.

Fig. 2 is a flowchart of a data transmission method according to another embodiment of the present invention.

FIG. 3A and FIG. 3B are schematic diagrams of a frame structure of a PPDU according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a frame structure of a PPDU according to another embodiment of the present invention.

Fig. 5 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention.

8A and 8B are schematic diagrams of a frame structure of a PPDU according to another embodiment of the present invention.

FIG. 9A and FIG. 9B are schematic diagrams of a frame structure of a PPDU according to another embodiment of the present invention.

Fig. 10 is a block diagram of a data transmission device according to an embodiment of the present invention.

Fig. 11 is a block diagram of a data transmission device according to another embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Fig. 1 is a flowchart of a data transmission method according to an embodiment of the present invention. The method in Figure 1 can be executed by a station or an access point.

101. Generate a PPDU. The PPDU includes N group length training domains, where N is a positive integer and is determined by the number of space-time streams (Space-time stream) adopted by the PPDU, and each group length training domain includes M long training domains, where M is a positive integer and for Different PPDUs are variable.

For example, when the PPDU adopts a single-stream transmission mode, the PPDU may include a group of LTFs, and the number of LTFs included in the group of LTFs may be variable. When the PPDU adopts a multi-stream transmission mode, the PPDU may include multiple sets of LTFs, wherein the number of LTFs included in each set of LTFs is variable.

Optionally, as an embodiment, the time domain position of the first long training field in each group of long training fields in the N groups of long training fields is a fixed position in the PPDU. The time domain positions of the second long training field to the Mth long training field in each group of long training fields are fixed positions or variable positions in the PPDU.

The fixed position means that the sending and receiving ends of the PPDU can only understand the position of the LTF in the PPDU in one way, and the way can be pre-specified.

The variable position means that the sending and receiving ends of the PPDU may understand the location of the LTF in the PPDU in various ways, and the way can be determined through negotiation between the sending and receiving ends. For example, the sending end of the PPDU may notify the receiving end of the PPDU of the location information indicating the variable location. Specifically, as a non-limiting embodiment, at least one of the following may carry the location information indicating the variable location: PPDU control signaling SIG, broadcast frame, request response frame, association response frame, newly defined management frame.

The embodiment of the present invention does not limit the form of the location information. Optionally, as an embodiment, the location information may indicate that the first long training domain in the N groups of long training domains includes between two adjacent long training domains (such as the first long training domain and the second long training domain). domain) time interval. In addition, other forms of location information can also be used, for example, it can be the time interval between the second long training field in the first group of long training fields and the starting point of the PPDU (that is, the short training field), or it can be the second long training field. The time interval between the long training field and other parts (for example, control signaling or data parts). These modes all fall within the scope of the embodiments of the present invention.

Optionally, as another embodiment, the location information is only valid for the receiving end that does not have the sleep capability. For example, for a receiving end capable of sleeping, the LTF can adopt the above-mentioned fixed position method.

Optionally, as another embodiment, when N is equal to 1, the PPDU may include a short training field, control signaling, data, and a group of long training fields. The first long training field in the group of long training fields is located between the short training field and the control signaling, and the remaining long training fields (the second long training field to the Mth long training field) are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU includes a short training field, control signaling, data, and N sets of long training fields. The first long training fields of the first set of long training fields in the N groups of long training fields are located between the short training fields and the control signaling, and the rest of the long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for multi-user transmission, the PPDU includes a short training field, a long training field for demodulating control signaling, control signaling, and a multi-user short training field , data, and N-group leader training domains for multiple users. The first long training domain of each group of long training domains in the N groups of long training domains is located between the multi-user short training domains and the data, and the rest of the long training domains are inserted into the data.

Optionally, as another embodiment, the value of M is jointly determined by the duration of the PPDU and the time domain positions of the second long training field to the Mth long training field of each group of long training fields.

In the following, a non-limiting example of a frame structure and a location information notification manner that may be adopted in the embodiments of the present invention will be described in more detail in combination with specific embodiments.

102. Send the foregoing PPDU to the receiving end.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

Fig. 2 is a flowchart of a data transmission method according to another embodiment of the present invention. The method in FIG. 2 can be executed by a station or an access point, and corresponds to the method in FIG. 1 , so repeated descriptions will be appropriately omitted.

201. Receive a PPDU. The PPDU includes N sets of long training fields, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each set of long training fields includes M long training fields, where M is a positive integer and is variable for different PPDUs.

Optionally, as an embodiment, the time domain position of the first long training domain in each group of long training domains in the N group of long training domains is a fixed position in the PPDU, and the second long training domain to the first long training domain of each group of long training domains The time domain position of the M-length training field in the PPDU is a fixed position or a variable position. The manner of fixing the position or changing the position is as described above, and will not be repeated here.

Optionally, as another embodiment, when the positions of the second long training field to the Mth long training field in the PPDU are variable positions, the position information carried by at least one of the following may also be used to determine the first Positions of the second long training field to the Mth long training field in the PPDU: PPDU control signaling, broadcast frame, request response frame, association response frame, newly defined management frame.

The embodiment of the present invention does not limit the form of the location information. Optionally, as an embodiment, the location information may represent two adjacent long training domains (such as the first long training domain and the second long training domain) included in the first group of long training domains in the N groups of long training domains time interval between. In addition, other forms of location information can also be used, for example, it can be the time interval between the second long training field in the first group of long training fields and the starting point of the PPDU (that is, the short training field), or it can be the second long training field. The time interval between the long training field and other parts (for example, control signaling or data parts). These modes all fall within the scope of the embodiments of the present invention.

Optionally, as another embodiment, the location information is only valid for the receiving end that does not have the sleep capability. For example, for a receiving end capable of sleeping, the LTF can adopt the above-mentioned fixed position method.

Optionally, as another embodiment, when N is equal to 1, the PPDU may include a short training field, control signaling, data, and a group of long training fields. The first long training field in the set of long training fields is located between the short training field and the control signaling, and the second to Mth long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU includes a short training field, control signaling, data, and N sets of long training fields. The first long training fields of the first set of long training fields in the N groups of long training fields are located between the short training fields and the control signaling, and the rest of the long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for multi-user transmission, the PPDU includes a short training field, a long training field for demodulating control signaling, control signaling, and a multi-user short training field , data, and N-group leader training domains for multiple users. The first long training domain of each group of long training domains in the N groups of long training domains is located between the multi-user short training domains and the data, and the rest of the long training domains are inserted into the data.

Optionally, as another embodiment, when the frame length of the PPDU is greater than a threshold value, it is determined that each group of long training fields includes two or more long training fields. The receiving end may determine the frame length of the PPDU in any existing manner, which is not limited in the present invention. For example, the receiving end can obtain the indication of the frame length from the control signaling part. Alternatively, the receiving end may determine whether a frame ends through energy detection, thereby determining the frame length.

This embodiment of the present invention does not limit the above threshold. For example, the threshold value can be a predefined value. Alternatively, the threshold value can be related to the time interval between LTFs, for example, the threshold value can be equal to the time interval plus the length of the short training field.

202. Perform channel estimation processing on the PPDU by using the N group length training field.

After determining the time domain position of the N group length training domain, the receiving end can use the LTF to perform channel estimation, so as to perform processing such as demodulation of the PPDU. For example, the function of the first LTF in each group of LTFs may be similar to that of the LTFs in the prior art, and is used to demodulate the SIG and some data segments. The rest of the LTFs can be used to demodulate part of the subsequent data segments.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

A non-limiting example of a frame structure and a location information notification manner that may be adopted in the embodiments of the present invention will be described in more detail below in conjunction with specific embodiments. It should be noted that these examples are only intended to help those skilled in the art better understand the embodiments of the present invention, rather than limiting the scope of the present invention.

The following example describes a data interaction process, but this embodiment of the present invention is not limited to the number of interactions. In addition, in the following example, the time interval between two long training domains is used as the indication method of the time domain position of the long training domain, but the embodiment of the present invention is not limited thereto, and other methods may be used to indicate the time domain position of the long training domain .

Embodiment one

FIG. 3A and FIG. 3B are schematic diagrams of a frame structure of a PPDU according to an embodiment of the present invention. In this embodiment, the time domain position of the first long training domain is always fixed, but in the prior art, under different bandwidths, the frame structure may be different, and at this time the time domain position of the first long training domain may be Varies with bandwidth. In the case of fixed bandwidth, the assumption that the temporal location of the first long training domain is always fixed still applies. Whether the time domain position of the first long training domain is fixed is not the key point of the present invention, but only to ensure logical flow, because if the time domain position of the first long training domain is variable, additional signaling is required to indicate the time domain of the first long training domain Location.

In the embodiment shown in Fig. 3A and Fig. 3B, the PPDU adopts a single-stream transmission mode, that is, N=1. At this time, the PPDU only includes 1 long training field, and it is assumed that this 1 long training field contains M long training fields, The time domain positions of the first long training field to the Mth long training field in the PPDU are fixed. It should be pointed out that other versions of WLAN protocols, such as 11n, include two long training fields: data long training fields (DLTF, Data-LTF) and extended long training fields (ELTF, Extension-LTF). In the case of single-stream transmission Next, there is only one set of data long training domains for data demodulation, and there may be multiple sets of extended long training domains for spatial channel measurement. Unless otherwise specified, the long training field in the embodiment refers to the long training field used for data demodulation.

For ease of description, it is assumed that the interaction scenario is a single interaction, that is, only one data transmission and reception is included. In this interaction, the station STA1 is the transmitter of the PPDU, and the station STA2 is the receiver of the PPDU. As shown in FIG. 3A , for a shorter PPDU, similar to the prior art, when STA1 transmits data at the transmitting end, it sequentially sends the short training field, the long training field, control signaling, and data.

As shown in FIG. 3B , for longer PPDUs, STA1 adds one or more long training fields in the middle of the data, so as to ensure better tracking of time domain changes of the channel. FIG. 3B depicts an example of inserting a long training field in the data, but the present invention is not limited thereto, and the number of inserted long training fields is not limited.

Specifically, since the time domain position of the first long training domain is fixed, if it is assumed that the first, second, ..., Mth long training domains are equally spaced, then the second long training domain to the Mth The time domain position of the long training field in the PPDU may be determined by the time interval T from the second long training field to the first long training field. Suppose the time interval between two long training domains is T, and the length of the short training domain is T _STF . The time interval T here is a fixed time interval, that is, it can be a predefined value, and there is no need for negotiation/notification between the sending and receiving ends. First, the transmitter STA1 estimates the frame length according to the assumption that there is only the first long training field, assuming it is T _PPDU , if T _PPDU is less than or equal to T+T _STF , then its frame structure is consistent with the existing technology, that is, here 1 The group length training field only contains the first long training field; and for frames whose T _PPDU is equal to or greater than T+T _STF , the second long training field is inserted at T+T _STF time to obtain a new frame length T'_PPDU; Similarly, for a frame whose T _PPDU is greater than or equal to or greater than 2T+T _STF , the third long training field is inserted at the time of 2T+T _STF , and so on. For simplicity of processing, the signal structure and transmission processing flow of the second long training field and the third long training field may be completely the same as those of the first long training field.

The selection method of the time interval T is illustrated below with an example. This fixed time interval T can be set to a better value according to application scenarios and simulation results, and this value needs to be an integer multiple of the OFDM symbol time. If multiple guard intervals (GI, Guard interval) need to be supported, the fixed time interval T needs to be an integer multiple of the OFDM symbol time length under multiple guard intervals at the same time. For example, assuming that the long GI OFDM symbol length is 40 μs (32 μs effective symbol + 8 μs guard interval), and the short GI OFDM symbol length is 36 μs (32 μs effective symbol + 4 μs guard interval), then the least common multiple that satisfies the multiple of both is 360μs, that is, the time interval between two long training domains must be an integer multiple of 360μs.

According to typical application scenarios, such as the supported maximum moving speed, the Doppler frequency can be simply calculated.

Doppler frequency (Hz) = moving speed (m/s) × carrier frequency (Hz) / light speed (m/s)

Calculated with a carrier frequency of 1GHz, for a moving speed of 3km/h (0.83m/s), its Doppler frequency is: 2.78Hz, and the optimal value, channel model and channel estimation for the time interval of the long training domain It is related to the method, and the general empirical value is more suitable between 1/10 and 1/100 of the reciprocal of Doppler frequency. Therefore, the fixed time interval in the above example may be (10˜100)*360 μs, that is, 3.6 ms to 36 ms.

At this time, the increased overhead is approximately: T _LTF /T, where T _LTF is the length of the long training field, which is a variable length and is related to the number of streams sent. For single-stream transmission, T _LTF is generally 2 OFDM symbols. For multi-stream transmission, each additional stream T _LTF will add one OFDM symbol. Taking 4 streams as an example, there are 5 OFDM symbols in total. Therefore, for a single stream, T=3.6ms, the increased overhead is about 2×40μs/3.6ms=2%; for 4 streams, the increased overhead is about 5%. If T is enlarged, the corresponding overhead will be reduced, but the obtained channel estimation performance improvement will also be reduced. Therefore, a trade-off between overhead and performance is required here, and the value of this trade-off can be obtained through simulation. At the receiving end STA2 of the PPDU, the receiving operation is similar to the normal receiving process.

Corresponding to the above example, if the received frame length is less than or equal to T+T _STF , then STA2 determines that the structure of the PPDU is similar to the existing structure, so STA2 can perform deframing, channel estimation, equalization, and demodulation according to the existing methods , Decoding operation.

If the received frame length is longer than T+T _STF , STA2 needs to interpret the frame fragments according to the new frame structure. For example, the time from T+T _STF to T+T _STF +T _LTF is the second longest training sequence, according to A common channel estimation algorithm processes this part of the received signal, and then updates the channel estimation value. Similarly, if the frame length is greater than 2T+T _STF , then the moment from 2T+T _STF to 2T+T _STF +T _LTF is the third longest training field, and this part of the received signal is also processed according to the usual channel estimation algorithm, and then The channel estimation value is updated, and so on for longer frames. Of course, more complex algorithms can be used, such as using the first long training field and the second long training field, or even more long training fields for joint channel estimation.

The STA2 at the receiving end can determine the frame length through control signaling, or determine whether a frame is over through energy detection, so as to determine the frame length. This process belongs to the prior art of WLAN and will not be repeated here.

Then, STA2 performs subsequent receiving processing such as equalization according to the channel estimation value obtained in the long training field. This process also belongs to the prior art and will not be repeated here.

In the embodiment of the present invention, for a PPDU with a long duration, a set of long training fields may include two or more long training fields for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios.

Embodiment two

Fig. 4 is a schematic diagram of a frame structure of a PPDU according to another embodiment of the present invention.

As shown in Figure 4, the difference from Embodiment 1 is that the time domain position of the first long training domain is fixed, and the time domain positions of the second long training domain to the Mth long training domain in the PPDU are variable. changing. For example, the time interval T of the first and second long training domains may be different for each frame, and there may be several alternative values, such as {T1, T2, T3, T4}. In this way, an optimal T value can be determined for the current moving speed of the target receiver in each frame. The variable time interval T is more flexible, but at the same time requires additional overhead. For example, if there are four T value options, correspondingly, 2 bits need to be added in the control signaling to indicate which time interval the frame adopts.

For example, B0-B1 bits of the control signaling may be used to indicate a variable time interval (ie, an example of location information of a long training field) as follows.

B0-B1:

00: The time interval between two LTFs is T1

01: The time interval between two LTFs is T2

10: The time interval between two LTFs is T3

11: The time interval between two LTFs is T4

Wherein, according to the recommended values in Embodiment 1, T1=3.6ms, T2=7.2ms, T3=10.8ms, T4=14.4ms.

Each set of long training domains in the embodiment of the present invention may include two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Embodiment three

Fig. 5 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention. In the embodiment of FIG. 5 , the access point AP notifies the stations STA1 and STA2 of the location information of the long training field (such as the variable time interval T in the second embodiment above) through a broadcast frame.

The difference between the third embodiment and the second embodiment is that the time interval between the two long training domains is notified by a broadcast frame (such as a beacon frame, Beacon), until the arrival of the next beacon frame, the current latest time interval is allow.

First, the AP sets the LTF time interval in the beacon frame, specifically adding a new information element (IE, information element) in the existing beacon frame to indicate the LTF time interval.

For example, an LTF interval (LTF interval) information element may be added in the frame body of the existing beacon frame to indicate the long training domain time interval adopted in the current beacon frame period. This cell is 1 byte and can represent 256 different long training domain time intervals. The embodiment of the present invention does not limit the time domain position of the LTF interval information element in the broadcast frame.

In the current beacon frame period, from the end of the current beacon frame to the arrival of the next beacon frame, all frames use the long training domain time interval set in LTF interval. The AP will periodically send beacon frames, and the AP can reset the long training interval in the next beacon frame.

In Figure 5, t1 to t2 is a beacon frame period, and delta_t is the sum of the frame length of the beacon frame + signal propagation + processing delay. From t1+delta_t to t2 is the effective time of the long training domain time interval setting.

In this case, since the long training domain time interval is uniform in a BSS, the AP needs to select a compromise value of the long training domain time interval according to the current moving speed of all STAs in the entire BSS to ensure that the value is Most STAs are superior.

Then, after each STA receives the beacon frame, it updates the information according to the long training domain time interval indicated in the beacon frame. If there is data transmission or data reception later, the data is sent and received according to the latest long training domain time interval. receiving process.

It should be pointed out that because some STAs have a sleep function, they may wake up in one beacon frame cycle, so that the long training domain time interval is not updated to the latest value, which will cause misalignment of the sending and receiving end information and cause demodulation errors. . For example, after sending a beacon frame, the AP sends and receives according to the long training domain time interval set in the beacon frame, but a certain STA wakes up after sending the beacon frame, and the next beacon frame If the data is sent and received before the arrival, then the STA uses the previously saved long training domain time interval for sending and receiving instead of the latest current value. Therefore, additional constraints need to be added. For this method of setting through beacon frames, it can only be used in BSSs that do not have STAs capable of sleeping.

Of course, in addition to the above beacon frame, a new broadcast frame can also be redesigned. The broadcast frame contains the LTF interval information element, which is specially used to set the time interval of the long training domain. The interaction process is exactly the same as that of the beacon frame, except that the carrier of the LTF interval information element is different.

Each group of long training domains in the embodiment of the present invention includes two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Embodiment four

Embodiment four is the combination of embodiment three and embodiment one. In the fourth embodiment, a constraint is added, that is, for the method set by the beacon frame, both the AP and the STA should be clear that it only takes effect for the STAs that do not have the sleep capability; for the STAs that have the sleep capability, use the method.

Embodiment five

Fig. 6 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention. In the embodiment of FIG. 6 , the access point AP notifies the station STA1 of the location information of the long training domain (such as the variable time interval T in the second embodiment above) through a probe response frame.

The difference between the fifth embodiment and the second embodiment is that the AP sets a long training domain time interval for each STA during the association process through the request response during the STA association.

As shown in Figure 6, first, STA1 sends a probe request (Probe request) frame, and the AP determines the LTF time interval by receiving the probe request frame (the specific method is not limited, for example, the Doppler frequency measurement described in Embodiment 1 can be used ).

Then, the AP sets the time interval of the long training domain in the probe response (Probe response) frame. Add an LTF interval information element in the existing probe response frame, which is used for the time interval setting of the long training domain. The embodiment of the present invention does not limit the time domain position of the LTF interval information element in the probe response frame.

Each group of long training domains in the embodiment of the present invention includes two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Embodiment six

Fig. 7 is a schematic diagram of a process of notifying location information according to an embodiment of the present invention. In the embodiment of FIG. 7 , the access point AP notifies the station STA1 of the location information of the long training domain (such as the variable time interval T in the second embodiment above) through an association response frame.

The difference between the sixth embodiment and the fifth embodiment is that the long training domain time interval is set for each STA during the association process through the association response frame.

As shown in Figure 7, first, STA1 sends an association request (Association request) frame, and the AP determines the LTF time interval by receiving the association request frame.

Then, the AP sets the time interval of the long training domain in the Association response (Association response) frame. Add an LTF interval information element in the existing association response frame, which is used for the time interval setting of the long training domain. The embodiment of the present invention does not limit the time domain position of the LTF interval information element in the association response frame.

Each group of long training domains in the embodiment of the present invention includes two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Of course, the LTF interval information element can also be added in other management frames to realize the time interval setting function of the long training domain.

Embodiment seven

The main difference between the seventh embodiment and the fifth embodiment is that a long training domain time interval is set for each STA during the association process through a newly defined management frame.

The management frame at least includes an LTF interval cell for setting a long training domain time interval, and the main difference from Embodiments 5 and 6 is only that the information carrier is different, and the sending and receiving process is the same.

Each group of long training domains in the embodiment of the present invention includes two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Embodiment eight

8A and 8B are schematic diagrams of a frame structure of a PPDU according to another embodiment of the present invention. In the embodiment shown in FIG. 8A and FIG. 8B , the PPDU adopts a multi-stream transmission mode for a single user.

The main difference between the eighth embodiment and the previous embodiments is that multiple long training fields are included during multi-stream transmission. For example, if N streams are transmitted (N is a positive integer greater than 1), N groups of long training fields are included. FIG. 8A is a frame structure when the frame length is short, which is the same as the frame structure used for single-user multi-stream transmission in the prior art. Each set of long training domains includes a long training domain, which are respectively long training domain 1, long training domain 2, . . . , long training domain N. The long training field 1 is located between the short training field and the control signaling, and is mainly used for the demodulation of the control signaling. In addition, the long training fields 1 to N are all used for the demodulation of subsequent data.

FIG. 8B is a frame structure when the frame length is long, and a long training field for data demodulation is added in each group of long training fields. For example, as shown in Figure 8B, among N group leader training domains, the first group leader training domain includes two or more long training domains 1, the second group leader training domain includes two or more long training domains 2, ... ..., the Nth long training domain includes two or more long training domains N. The first long training field 1 is located between the short training field and control signaling, and is mainly used for demodulation of control signaling and data. In addition, the rest of the long training field is used for demodulation of subsequent data.

At this time, the intervals between the two long training domains 1 and the other two long training domains (for example, the two long training domains 2 ) are not equal. In the case of using a variable time interval, the transmitter only needs to notify the interval between two long training fields 1, and the specific notification method is the same as the previous embodiment. The receiver finds the position of the second long training field 1 according to the interval, and then can find the position of the second long training field 2-N. The position of the subsequent long training domain can be deduced in this way.

Each group of long training domains in the embodiment of the present invention includes two or more long training domains for channel estimation, so as to better reflect channel conditions and adapt to low-speed data transmission scenarios. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Embodiment nine

FIG. 9A and FIG. 9B are schematic diagrams of a frame structure of a PPDU according to another embodiment of the present invention. In the embodiments shown in FIG. 9A and FIG. 9B , the PPDU adopts a multi-stream transmission mode for multiple users.

The main difference between the ninth embodiment and the eighth embodiment is that the N streams may be transmitted to different users. FIG. 9A is a frame structure when the frame length is short, which is the same as the frame structure used for multi-stream transmission of multiple users in the prior art. As shown in FIG. 9A , the PPDU includes a short training field, a long training field LTF for demodulating control signaling, control signaling, multi-user short training fields, multi-user data, and multi-user long training fields 1 to N.

The long training field LTF used for demodulation of control signaling is located between the short training field and control signaling, and is mainly used for demodulation of control signaling. Multi-user long training fields 1 to N are used for demodulation of multi-user data later.

FIG. 9B is a frame structure when the frame length is long, and a long training field for multi-user data demodulation is added to each group of long training fields.

In the case of using a variable time interval, the transmitter only needs to notify the interval between two adjacent multi-user long training fields (for example, two adjacent multi-user long training fields 1 ) in each group. The specific notification method is the same as the previous embodiment. The receiver finds the position of the multi-user long training domain 1 according to the interval, and then the positions of the long training domains 2 to N can be found.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission. Moreover, the use of variable time intervals allows more flexibility for long training domain settings.

Fig. 10 is a block diagram of a data transmission device according to an embodiment of the present invention. The data transmission apparatus 1000 in FIG. 10 may be an access point or a station, and includes a generating unit 1010 and a sending unit 1020 .

The generating unit 1010 generates a PPDU. The PPDU includes N sets of long training fields, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each set of long training fields includes M long training fields, where M is a positive integer and is variable for different PPDUs. The sending unit 1020 sends the PPDU generated by the generating unit 1010 to the receiving end.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

The data transmission device 1000 can implement each step of the method in FIG. 1 , and details are not repeated here to avoid repetition.

Optionally, as an embodiment, the time domain position of the first long training domain in each group of long training domains in the N group of long training domains is a fixed position in the PPDU, and the second long training domain to the first long training domain of each group of long training domains The time domain position of the M-length training field in the PPDU is a fixed position or a variable position. The manner of fixing the position or changing the position is as described above, and will not be repeated here.

Optionally, as another embodiment, when the time domain positions of the second long training field to the Mth long training field in the PPDU are variable positions, the generation unit 1010 may also carry an indication by at least one of the following The position information of the time domain positions of the second long training field to the Mth long training field in the PPDU: PPDU control signaling, broadcast frame, request response frame, association response frame, newly defined management frame (for example, the above-mentioned embodiment two to nine).

Optionally, as another embodiment, the location information may represent two adjacent long training domains (such as the first long training domain and the second long training domain) included in the first group of long training domains in the N groups of long training domains. ) between time intervals (for example, the above-mentioned Embodiments 2 to 9).

Optionally, as another embodiment, the location information is only valid for the receiving end that does not have the sleep capability. For example, for a receiving end capable of sleeping, the LTF can adopt the above-mentioned fixed position method.

Optionally, as another embodiment, when N is equal to 1, the PPDU may include a short training field, control signaling, data, and a group of long training fields. The first long training field in the set of long training fields is located between the short training field and the control signaling, and the second to Mth long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU includes a short training field, control signaling, data, and N sets of long training fields. The first long training fields of the first set of long training fields in the N groups of long training fields are located between the short training fields and the control signaling, and the rest of the long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for multi-user transmission, the PPDU includes a short training field, a long training field for demodulating control signaling, control signaling, and a multi-user short training field , data, and N-group leader training domains for multiple users. The first long training domain of each group of long training domains in the N groups of long training domains is located between the multi-user short training domains and the data, and the rest of the long training domains are inserted into the data.

Fig. 11 is a block diagram of a data transmission device according to another embodiment of the present invention. The data transmission apparatus 1100 in FIG. 11 may be an access point or a station, and includes a receiving unit 1110 and a processing unit 1120 .

The receiving unit 1110 receives a PPDU. The PPDU includes N sets of long training fields, where N is a positive integer and is determined by the number of space-time flows used by the PPDU, and each set of long training fields includes M long training fields, where M is a positive integer and is variable for different PPDUs. The processing unit 1120 performs channel estimation processing on the PPDU received by the receiving unit 1110 by using the N group length training field.

The number of long training fields included in each group of long training fields in the embodiment of the present invention can be changed according to the situation of the PPDU, so as to better reflect channel conditions and adapt to scenarios of low-speed data transmission.

The data transmission device 1100 can implement each step of the method in FIG. 2 , and details are not repeated here to avoid repetition.

Optionally, as an embodiment, the time domain position of the first long training domain in each group of long training domains in the N group of long training domains is a fixed position in the PPDU, and the second long training domain to the first long training domain of each group of long training domains The time domain position of the M-length training field in the PPDU is a fixed position or a variable position. The manner of fixing the position or changing the position is as described above, and will not be repeated here.

Optionally, as another embodiment, when the time domain positions of the second long training field to the Mth long training field in the PPDU are variable positions, the determining unit 1120 may also use at least one of the following carried Position information, to determine the time domain positions of the second long training field to the Mth long training field in the PPDU: PPDU control signaling, broadcast frame, request response frame, association response frame, newly defined management frame.

Optionally, as another embodiment, the location information may represent two adjacent long training domains (such as the first long training domain and the second long training domain) included in the first group of long training domains in the N groups of long training domains. ) between time intervals.

Optionally, as another embodiment, the receiving unit 1110 may determine that each set of long training fields includes two or more long training fields when the frame length of the PPDU is greater than a threshold.

Optionally, as another embodiment, the location information is only valid for the device 1100 that does not have the sleep capability. For example, for the device 1100 capable of sleeping, the LTF may adopt the above-mentioned fixed position method.

Optionally, as another embodiment, when N is equal to 1, the PPDU may include a short training field, control signaling, data, and a group of long training fields. The first long training field in the set of long training fields is located between the short training field and the control signaling, and the second to Mth long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU includes a short training field, control signaling, data, and N sets of long training fields. The first long training fields of the first set of long training fields in the N groups of long training fields are located between the short training fields and the control signaling, and the rest of the long training fields are inserted into the data.

Optionally, as another embodiment, when N is greater than 1 and the PPDU is used for multi-user transmission, the PPDU includes a short training field, a long training field for demodulating control signaling, control signaling, and a multi-user short training field , data, and N-group leader training domains for multiple users. The first long training domain of each group of long training domains in the N groups of long training domains is located between the multi-user short training domains and the data, and the rest of the long training domains are inserted into the data.

A communication system according to an embodiment of the present invention may include the above-mentioned data communication device 1000 or 1100 .

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

Those skilled in the art can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.

If the functions described above are realized in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the essence of the technical solution of the present invention or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disc, etc., which can store program codes. .

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (20)

1. A data transmission method for a wireless local area network, comprising:

generating a physical layer convergence Process Protocol Data Unit (PPDU), wherein the PPDU comprises N groups of long training fields, N is a positive integer and is determined by the number of space-time streams adopted by the PPDU, each group of long training fields comprises M long training fields, and M is a positive integer and is variable for different PPDUs;

and sending the PPDU to a receiving end.

2. The data transmission method of claim 1, wherein a time domain position of a second through an Mth long training fields of each of the N sets of long training fields in the PPDU is a fixed position or a variable position.

3. The data transmission method of claim 2, wherein in case that the time domain position of the second to mth long training fields of each set of long training fields in the PPDU is a variable position, the method further comprises:

carrying location information indicative of the variable location by at least one of: control signaling, broadcast frame, request response frame, association response frame and newly defined management frame of the PPDU.

4. The method of claim 3, wherein the location information is effective only for receivers that do not have sleep capability.

5. The method of claim 3 or 4, wherein the location information indicates a time interval between a first long training field and a second long training field included in a first set of the N sets of long training fields.

6. The method of any one of claims 1 to 4,

when N is equal to 1, the PPDU comprises a short training field, control signaling, data and a group of long training fields, wherein a first long training field in the group of long training fields is positioned between the short training field and the control signaling, and second to Mth long training fields are inserted into the data; or,

when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU comprises a short training field, control signaling, data and N groups of long training fields, wherein a first long training field of a first group of long training fields in the N groups of long training fields is positioned between the short training field and the control signaling, and the rest long training fields are inserted into the data; or,

when N is larger than 1 and the PPDU is used for multi-user transmission, the PPDU comprises a short training field, a long training field for demodulating control signaling, a multi-user short training field, data and N groups of long training fields for multiple users, wherein the first long training field of each group of long training fields in the N groups of long training fields is positioned between the multi-user short training field and the data, and the rest long training fields are inserted into the data.

7. The data transmission method of claim 1, wherein a value of M is determined by a duration of the PPDU and a time domain position from the second long training field to the mth long training field of each group of long training fields.

8. A method of data transmission, comprising:

receiving a physical layer convergence Process Protocol Data Unit (PPDU), wherein the PPDU comprises N groups of long training fields, N is a positive integer and is determined by the number of space-time streams adopted by the PPDU, each group of long training fields comprises M long training fields, and M is a positive integer and is variable for different PPDUs;

and performing channel estimation processing on the PPDU by using the N groups of long training fields.

9. The method of claim 8, wherein a time domain position of a second through an Mth long training fields of each of the N sets of long training fields in the PPDU is a fixed position or a variable position.

10. The method of claim 9, wherein in a case that a time domain position of a second through an Mth long training fields of each set of long training fields in the PPDU is a variable position, the method further comprises:

determining the time domain positions of the second long training field to the Mth long training field of each group of long training fields in the PPDU according to the position information carried by at least one of the following: control signaling, broadcast frame, request response frame, association response frame and newly defined management frame of the PPDU.

11. The method of claim 10, wherein the location information indicates a time interval between a first long training field and a second long training field included in a first set of the N sets of long training fields.

12. The method of any one of claims 7-11,

when N is equal to 1, the PPDU comprises a short training field, control signaling, data and a group of long training fields, wherein a first long training field in the group of long training fields is positioned between the short training field and the control signaling, and second to Mth long training fields are inserted into the data; or,

when N is greater than 1 and the PPDU is used for single-user transmission, the PPDU comprises a short training field, control signaling, data and N groups of long training fields, wherein a first long training field of a first group of long training fields in the N groups of long training fields is positioned between the short training field and the control signaling, and the rest long training fields are inserted into the data; or,

when N is larger than 1 and the PPDU is used for multi-user transmission, the PPDU comprises a short training field, a long training field for demodulating control signaling, a multi-user short training field, data and N groups of long training fields for multiple users, wherein the first long training field of each group of long training fields in the N groups of long training fields is positioned between the multi-user short training field and the data, and the rest long training fields are inserted into the data.

13. A data transmission apparatus, comprising:

a generating unit, configured to generate a physical layer convergence procedure protocol data unit PPDU, where the PPDU includes N groups of long training fields, where N is a positive integer and is determined by a number of space-time streams adopted by the PPDU, and each group of long training fields includes M long training fields, where M is a positive integer and is variable for different PPDUs;

a sending unit, configured to send the PPDU generated by the generating unit to a receiving end.

14. The apparatus of claim 13, wherein a time domain position of a second through an mth long training fields of each of the N sets of long training fields in the PPDU is a fixed position or a variable position.

15. The apparatus of claim 14, wherein in a case that a time domain position of a second through an mth long training fields of each set of long training fields in the PPDU is a variable position, the generating unit is further configured to carry position information indicating the variable position by at least one of: control signaling, broadcast frame, request response frame, association response frame and newly defined management frame of the PPDU.

16. The apparatus of claim 15, wherein the location information represents a time interval between a first long training field and a second long training field included in a first set of the N sets of long training fields.

17. A data transmission apparatus, comprising:

a receiving unit, configured to receive a physical layer convergence procedure protocol data unit PPDU, where the PPDU includes N groups of long training fields, where N is a positive integer and is determined by a number of space-time streams adopted by the PPDU, and each group of long training fields includes M long training fields, where M is a positive integer and is variable for different PPDUs;

and the processing unit is used for performing channel estimation processing on the PPDU received by the receiving unit by using the N groups of long training fields.

18. The apparatus of claim 17, wherein a position of a second through an mth long training fields of each of the N sets of long training fields in the PPDU is a fixed position or a variable position.

19. The apparatus of claim 18, wherein in case that the time domain position of the second to mth long training fields of each set of long training fields in the PPDU is a variable position, the determining unit is further configured to determine the time domain position of the second to mth long training fields of each set of long training fields in the PPDU by location information carried by at least one of: control signaling, broadcast frame, request response frame, association response frame and newly defined management frame of the PPDU.

20. The apparatus of claim 19, wherein the time domain location information represents a time interval between a first long training field and a second long training field included in a first set of the N sets of long training fields.

Images