CN104104469B

CN104104469B - Data transmission method, transmitting terminal, receiving terminal and system

Info

Publication number: CN104104469B
Application number: CN201310119604.3A
Authority: CN
Inventors: 刘永俊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Global Innovation Polymerization LLC; Gw Partnership Co ltd
Priority date: 2013-04-08
Filing date: 2013-04-08
Publication date: 2017-10-03
Anticipated expiration: 2033-04-08
Also published as: CN104104469A

Abstract

The invention discloses a kind of data transmission method, transmitting terminal, receiving terminal and system, belong to the communications field.Methods described includes：First duration is determined according to preparatory condition, first duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol；The previous OFDM symbol according to first duration and transmission signal generation so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol is equal to first duration；The previous OFDM symbol is sent to receiving terminal.The transmitting terminal includes：First determining module, generation module and sending module.The receiving terminal includes：Receiving module and processing module.The system includes：Transmitting terminal and receiving terminal.The cyclic prefix that the present invention solves the transmission duration equal with protection interval duration wastes transfer resource, and the problem of consuming extra transmission energy has reached the effect saved and send energy.

Description

Data transmission method, transmitting terminal, receiving terminal and system

Technical field

The present invention relates to the communications field, more particularly to a kind of data transmission method, transmitting terminal, receiving terminal and system.

Background technology

OFDM（Orthogonal Frequency Division Multiplexing, OFDM）It is that one kind is more Carrier wave, can be divided into several orthogonal subcarriers, highspeed serial data stream is converted into low-speed parallel by multi-carrier modulation scheme Sub-data flow, and be modulated on each subcarrier and be transmitted.Wherein, carrier wave is the waveform for being modulated to transmit signal, generally It is sinusoidal waveform.

Signal may reach receiving terminal in transmitting procedure by mulitpath so that the signal that receiving terminal is received is The superposition of the component of signal of mulitpath.Because component of signal is different by the transmission time in different paths, cause different paths There is interference between the component of signal of transmission, so, modulate signals into after OFDM symbol is transmitted, the OFDM of previous transmissions Symbol can be interfered to the OFDM symbol of following transmission.A prefix, shape are added generally before each OFDM symbol Into a protection interval, if the time long enough of protection interval, receiving terminal is when receiving previous OFDM symbol, previous OFDM symbols Number interference produced can fall in the protection interval of previous OFDM symbol, it is to avoid to the interference problem of previous OFDM symbol.

If protection interval is set into sky, when being demodulated to previous OFDM symbol, the son load in previous OFDM symbol The integration of ripple is possible to not within a complete cycle, so that the interference between producing subcarrier, reduces the performance of system.Cause This, for each subcarrier in previous OFDM symbol, can transmit circulation corresponding with the subcarrier in protection interval Prefix, the duration of the cyclic prefix is equal to the duration of protection interval.Wherein, cyclic prefix is the interior biography of final time section in subcarrier Defeated signal so that the integration of the subcarrier is within a complete cycle, it is to avoid the interference problem between subcarrier.One OFDM symbol includes ating least one the subcarrier through ovennodulation.Specifically, the schematic diagram of the OFDM symbol shown in Fig. 1 is refer to, Illustrated in figure so that OFDM symbol includes 4 subcarriers as an example, each subcarrier is included within the cycle of an OFDM symbol A complete times of cycle, and a cycle is differed between adjacent sub-carrier.

Because protection interval is obtained according to the channel parameter in the case of poor, therefore, what protection interval was typically chosen It is larger, and the cyclic prefix for transmitting the duration equal with protection interval duration wastes transfer resource, consumes extra transmission Energy.

The content of the invention

In order to which the cyclic prefix for solving to transmit the duration equal with protection interval duration wastes transfer resource, volume is consumed The problem of outer transmission energy, the embodiments of the invention provide a kind of data transmission method, transmitting terminal, receiving terminal and system.Institute State technical scheme as follows：

In a first aspect, the invention provides a kind of data transmission method, methods described includes：

First duration is determined according to preparatory condition, first duration is less than in current orthogonal frequency division multiplex OFDM symbol The duration of protection interval；

The previous OFDM symbol according to first duration and transmission signal generation so that the previous OFDM symbol The duration of cyclic prefix in protection interval is equal to first duration；

The previous OFDM symbol is sent to receiving terminal.

It is described that first duration is determined according to preparatory condition in the first possible implementation of first aspect, it is described First duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol, including：

The minimum value T1 of first duration is determined according to the preparatory condition；

First duration is determined according to the minimum value T1 and the protection interval duration T2 so that when described first Length belongs to [T1, T2）；

When the preparatory condition includes maximum delay extension and the timing error of the previous OFDM symbol of present channel It is at least one of long, when a length of receiving terminal handles the previous OFDM symbol during timing error, according to determination The duration of the period of the original position biased forwards of signal is transmitted in the previous OFDM symbol.

With reference to the first possible implementation of first aspect, in second of possible implementation of first aspect In, the minimum value T1 that first duration is determined according to the preparatory condition, including：

If the preparatory condition only maximum delay including the present channel extends, the present channel is obtained most Long time delay is extended, and the maximum delay got extension is defined as into the minimum value T1；Or,

If the preparatory condition only includes the timing error duration, the timing error duration is obtained, will be got The timing error duration be defined as the minimum value T1；Or,

If the preparatory condition includes the maximum delay extension of the present channel and the timing error duration, obtain The maximum delay extension of the present channel, and obtain the timing error duration；The maximum delay is extended and described fixed When error duration in a larger value be defined as the minimum value T1.

With reference to second of possible implementation of first aspect, in the third possible implementation of first aspect In, the maximum delay extension for obtaining the present channel, including：

The packet fed back according to the receiving terminal calculates the maximum delay extension；Or,

Receive the maximum delay extension that the packet that the receiving terminal sends according to transmitting terminal is calculated and fed back.

With reference to second of possible implementation of first aspect, in the 4th kind of possible implementation of first aspect In, the acquisition timing error duration, including：

Determine the timing error duration；Or, receive the timing error duration that the receiving terminal is determined and fed back.

With reference to the first possible implementation or first aspect of first aspect second of possible implementation or 4th kind of possible implementation of the third possible implementation or first aspect of first aspect, the of first aspect In five kinds of possible implementations, before the previous OFDM symbol according to first duration and transmission signal generation, Also include：

The Packet Error Ratio of at least one OFDM symbol before sending the previous OFDM symbol is obtained, the Packet Error Ratio is will At least one described OFDM symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

First duration, the size of the Packet Error Ratio and first duration are adjusted according to the size of the Packet Error Ratio Length correlation so that first duration after adjustment still falls within [T1, T2）.

With reference to the 5th kind of possible implementation of first aspect, in the 6th kind of possible implementation of first aspect In, the Packet Error Ratio for obtaining at least one OFDM symbol before sending the previous OFDM symbol, including：

Calculate the Packet Error Ratio；Or, receive the Packet Error Ratio that the receiving terminal is calculated and fed back.

Second aspect, the invention provides a kind of data transmission method, methods described includes：

The current orthogonal frequency division multiplex OFDM symbol that receiving end/sending end is sent, the previous OFDM symbol by the first duration and Signal generation is transmitted, first duration is determined by preparatory condition so that first duration is less than the previous OFDM symbol In protection interval duration and the cyclic prefix in the protection interval of the previous OFDM symbol duration be equal to described first Duration；

The previous OFDM symbol is handled.

In the first possible implementation of second aspect, the current orthogonal frequency division that the receiving end/sending end is sent is answered Before OFDM symbol, in addition to：

The packet that the transmitting terminal is sent is received, and the maximum delay for calculating present channel according to the packet expands Exhibition；

The maximum delay extension that calculating is obtained feeds back to the transmitting terminal.

In second of possible implementation of second aspect, the current orthogonal frequency division that the receiving end/sending end is sent is answered Before OFDM symbol, in addition to：

The timing error duration of the previous OFDM symbol is determined, a length of receiving terminal processing is described during the timing error works as During preceding OFDM symbol, according to the period for the original position biased forwards that signal is transmitted in the previous OFDM symbol of determination Duration；

The timing error duration after determination is fed back into the transmitting terminal.

In the third possible implementation of second aspect, the current orthogonal frequency division that the receiving end/sending end is sent is answered Before OFDM symbol, in addition to：

At least one OFDM symbol that the transmitting terminal is sent is received, and institute is calculated according at least one described OFDM symbol State Packet Error Ratio；

The Packet Error Ratio is fed back into the transmitting terminal.

The third aspect, the invention provides a kind of transmitting terminal, the transmitting terminal includes：

First determining module, for determining the first duration according to preparatory condition, first duration is less than current orthogonal frequency The duration for the protection interval divided in multiplexing OFDM symbol；

Generation module, for described in first duration that is determined according to first determining module and transmission signal generation Previous OFDM symbol so that when the duration of the cyclic prefix in the protection interval of the previous OFDM symbol is equal to described first It is long；

Sending module, the previous OFDM symbol for sending the generation module generation to receiving terminal.

In the first possible implementation of the third aspect, first determining module, including：

First determining unit, the minimum value T1 for determining first duration according to the preparatory condition；

Second determining unit, for the minimum value T1 determined according to first determining unit and the protection interval Duration T2 determine first duration so that first duration belongs to [T1, T2）；

With reference to the first possible implementation of the third aspect, in second of possible implementation of the third aspect In, first determining unit, including：

If the preparatory condition only maximum delay including the present channel extends, first obtains subelement, is used for Obtain the maximum delay extension of the present channel；First determination subelement, for the described first acquisition subelement to be got The maximum delay extension be defined as the minimum value T1；Or,

If the preparatory condition only includes the timing error duration, second obtains subelement, described fixed for obtaining When error duration；Second determination subelement, the timing error duration for the described second acquisition subelement to be got is true It is set to the minimum value T1；Or,

If the preparatory condition includes maximum delay extension and the timing error duration, first of the present channel Subelement is obtained, the maximum delay for obtaining the present channel extends；Second obtains subelement, for obtaining the timing Error duration；3rd determination subelement, for the maximum delay extension for getting the described first acquisition subelement and institute State a value larger in the timing error duration that the second acquisition subelement is got and be defined as the minimum value T1.

With reference to second of possible implementation of the third aspect, in the third possible implementation of the third aspect In, described first obtains subelement, and the packet for being fed back according to the receiving terminal calculates the maximum delay and extended；Or Person, the maximum delay extension that the packet that the reception receiving terminal is sent according to transmitting terminal is calculated and fed back.

With reference to second of possible implementation of the third aspect, in the 4th kind of possible implementation of the third aspect In, described second obtains subelement, for determining the timing error duration；Or, receive the receiving terminal and determine and feed back The timing error duration.

With reference to the first possible implementation or the third aspect of the third aspect second of possible implementation or 4th kind of possible implementation of the third possible implementation or the third aspect of the third aspect, the of the third aspect In five kinds of possible implementations, the transmitting terminal also includes：

Acquisition module, is accorded with for the generation module current OFDM according to first duration and transmission signal generation Before number, the Packet Error Ratio of at least one OFDM symbol before sending the previous OFDM symbol is obtained, the Packet Error Ratio is will At least one described OFDM symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

Adjusting module, when the size of the Packet Error Ratio for being got according to the acquisition module adjusts described first It is long, the size of the Packet Error Ratio and the length correlation of first duration so that first duration after adjustment Still fall within [T1, T2）.

With reference to the 5th kind of possible implementation of the third aspect, in the 6th kind of possible implementation of the third aspect In, the acquisition module, for calculating the Packet Error Ratio；Or, receive the Packet Error Ratio that the receiving terminal is calculated and fed back.

Fourth aspect, the invention provides a kind of receiving terminal, the receiving terminal includes：

Receiving module, the current orthogonal frequency division multiplex OFDM symbol sent for receiving end/sending end, the current OFDM symbols Number by the first duration and transmission signal generation, first duration determines by preparatory condition so that first duration is less than institute State protection interval in previous OFDM symbol duration and the cyclic prefix in the protection interval of the previous OFDM symbol when It is long to be equal to first duration；

Processing module, for handling the previous OFDM symbol that the receiving module is received.

In the first possible implementation of fourth aspect, the receiving terminal also includes：

First computing module, the current orthogonal frequency division multiplex OFDM symbol sent for the receiving module receiving end/sending end Before, the packet that the transmitting terminal is sent is received, and the maximum delay for calculating present channel according to the packet extends；

First feedback module, institute is fed back to for first computing module to be calculated into the extension of the obtained maximum delay State transmitting terminal.

In second of possible implementation of fourth aspect, the receiving terminal also includes：

Second determining module, the current orthogonal frequency division multiplex OFDM symbol sent for the receiving module receiving end/sending end Before, the timing error duration of the previous OFDM symbol is determined, a length of receiving terminal processing is described current during the timing error During OFDM symbol, according in the previous OFDM symbol of determination transmit signal original position biased forwards period when It is long；

Second feedback module, for the timing error duration after second determining module determination to be fed back into described Transmitting terminal.

In the third possible implementation of fourth aspect, the receiving terminal also includes：

Second computing module, the current orthogonal frequency division multiplex OFDM symbol sent for the receiving module receiving end/sending end Before, at least one OFDM symbol that the transmitting terminal is sent is received, and according to being calculated at least one described OFDM symbol Packet Error Ratio；

3rd feedback module, the transmission is fed back to for second computing module to be calculated into the obtained Packet Error Ratio End.

5th aspect, the invention provides a kind of data transmission system, the system includes：Transmitting terminal as described above and Receiving terminal as described above.

The beneficial effect that technical scheme provided in an embodiment of the present invention is brought is：

By determining the first duration according to preparatory condition, first duration is less than current orthogonal frequency division multiplex OFDM symbol In protection interval duration；The previous OFDM symbol according to first duration and transmission signal generation so that described to work as The duration of cyclic prefix in the protection interval of preceding OFDM symbol is equal to first duration；Send described current to receiving terminal OFDM symbol, the cyclic prefix for solving the transmission duration equal with protection interval duration wastes transfer resource, consumes volume The problem of outer transmission energy, the effect saved and send energy is reached.

Brief description of the drawings

Technical scheme in order to illustrate the embodiments of the present invention more clearly, makes required in being described below to embodiment Accompanying drawing is briefly described, it should be apparent that, drawings in the following description are only some embodiments of the present invention, for For those of ordinary skill in the art, on the premise of not paying creative work, other can also be obtained according to these accompanying drawings Accompanying drawing.

Fig. 1 is the schematic diagram for the OFDM symbol that prior art is provided；

Fig. 2 is the method flow diagram for the data transmission method that the embodiment of the present invention one is provided；

Fig. 3 is the method flow diagram for the data transmission method that the embodiment of the present invention two is provided；

Fig. 4 is the schematic diagram for the previous OFDM symbol that the embodiment of the present invention two is provided；

Fig. 5 is the structural representation for the data transmission system that the embodiment of the present invention three is provided；

Fig. 6 is the structural representation for the data transmission system that the embodiment of the present invention four is provided；

Fig. 7 is the structural representation for the data transmission system that the embodiment of the present invention five is provided；

Fig. 8 is the structural representation for the data transmission system that the embodiment of the present invention six is provided；

Fig. 9 is the structural representation for the data transmission system that the embodiment of the present invention seven is provided.

Embodiment

To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to embodiment party of the present invention Formula is described in further detail.

Embodiment one

Fig. 2 is refer to, the method flow diagram of the data transmission method provided it illustrates the embodiment of the present invention one.The data Transmission method, including：

Step 201, transmitting terminal determines the first duration according to preparatory condition, and first duration is less than in previous OFDM symbol The duration of protection interval；

The duration of protection interval is the fixed value calculated according to channel situation, the typically larger than delay spread of channel, To improve the practicality of protection interval.Wherein, delay spread refers to the difference of maximum transmitted time delay and minimum transfer time delay, transmission Time delay refer to signal be sent to the other end from one end required for time.Due to channel delay spread with surrounding landform, hair The factors such as the distance between sending end and receiving terminal are relevant, therefore, in order to meet the demand of major applications, the duration of protection interval Delay spread in the case of often selection channel is poor.Certainly, what the duration of protection interval can not be selected is too big, because after all Extra bandwidth and energy are consumed, the handling capacity of system can be reduced.Such as, it may be predetermined that the time delay of normal distribution expands Exhibition, then can calculate the mean square deviation of the delay spread when receiving signal, the duration of protection interval is set into the 4 of the mean square deviation Again, the delay spread that the duration of this protection interval can be more than 99%.Again such as, the duration of protection interval can be set to The 1/5 of the duration of whole OFDM symbol.

Due to protection interval typically choose it is larger, therefore, in order to avoid transmit it is corresponding with protection interval duration circulate Prefix can cause the waste of transfer resource, and the problem of consuming extra transmission energy, transmitting terminal can be according to default condition The first duration is determined, cyclic prefix is transmitted in first duration, first duration is less than the duration of protection interval.Wherein, one The first duration of all subcarriers is identical in individual OFDM symbol.

Step 202, transmitting terminal is according to the first duration and transmission signal generation previous OFDM symbol so that previous OFDM symbol Protection interval in cyclic prefix duration be equal to first duration；

Specifically, after transmitting terminal will transmit signal modulation into subcarrier, when can add default before transmitting the signal Long protection interval, and cyclic prefix is copied into the last of the protection interval, so as to generate OFDM symbol.Wherein, before circulation The duration sewed is equal to the first duration.

Step 203, transmitting terminal sends previous OFDM symbol to receiving terminal；

Transmitting terminal can be transmitted to OFDM symbol, so that receiving terminal is received after the OFDM symbol to the OFDM symbol Handled, so as to get the transmission signal carried in OFDM symbol.

Step 204, the previous OFDM symbol that receiving terminal receiving end/sending end is sent, the previous OFDM symbol by the first duration and Signal generation is transmitted, the first duration is determined by preparatory condition so that the first duration is less than the protection interval in previous OFDM symbol Duration and the cyclic prefix in the protection interval of previous OFDM symbol duration be equal to the first duration；

Step 205, receiving terminal is handled previous OFDM symbol.

Receiving terminal can be determined to transmit the original position of signal, so as to be handled from the original position, transmitted Signal.

In summary, data transmission method provided in an embodiment of the present invention, by determining the first duration according to preparatory condition, First duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol；According to first duration and Transmit previous OFDM symbol described in signal generation so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol Equal to first duration；The previous OFDM symbol is sent to receiving terminal, transmission is solved equal with protection interval duration The cyclic prefix of duration wastes transfer resource, the problem of consuming extra transmission energy, has reached and has saved transmission energy Effect.

Embodiment two

Fig. 3 is refer to, the method flow diagram of the data transmission method provided it illustrates the embodiment of the present invention two.The data Transmission method, including：

Step 301, transmitting terminal determines the minimum value T1 of the first duration according to preparatory condition；

In order to ensure the integration of sub-carrier within a complete cycle, transmitting terminal can be according to preparatory condition to circulation The duration of prefix sets minimum value, as long as then the duration of cyclic prefix is more than or equal to the minimum value, when demodulating subcarrier just not The interference between subcarrier can be caused.Wherein, preparatory condition can include maximum delay extension and the current OFDM symbols of present channel Number at least one of timing error duration, during timing error during a length of receiving terminal processing previous OFDM symbol, according to determination Previous OFDM symbol in transmission signal original position biased forwards period duration.

Because Multipath Transmission can cause delay spread, therefore, as long as the first duration is more than or equal to when transmitting OFDM symbol Maximum delay extends, then can ensure the integration of subcarrier within a complete cycle.Wherein, maximum delay, which extends, to be The maximum delay extension of most data bag, such as, and the maximum delay extension of 99% data above bag, or, predefine one Plant the distribution of delay spread, such as Gaussian Profile, the mean square deviation of the delay spread of measurement data bag, the equal of delay spread again of fetching Variance extends as maximum delay.Generally, maximum delay extension is more than 4 times of mean square deviation.

Further, it is contemplated that the timing error of OFDM symbol, receiving terminal is it is determined that transmit rising for signal in OFDM symbol , can be according to the original position biased forwards for a period of time, to improve receptivity behind beginning position.Therefore, transmitting terminal is also needed to Determine that the first duration is more than or equal to the timing error duration of the OFDM symbol.

Specifically, the minimum value T1 of the first duration is determined according to preparatory condition, can be included：

If the preparatory condition only maximum delay including present channel extends, the maximum delay extension of present channel is obtained, The maximum delay got extension is defined as minimum value T1；Or,

If preparatory condition only includes timing error duration, timing error duration is obtained, during by the timing error got Length is defined as minimum value T1；Or,

If preparatory condition includes maximum delay extension and the timing error duration of present channel, present channel is obtained most Long time delay extends, and obtains timing error duration；Maximum delay is extended and determined with a value larger in timing error duration For minimum value T1.

Wherein, the maximum delay extension of present channel is obtained, can be included：

The packet fed back according to receiving terminal calculates maximum delay extension；Or,

The maximum delay extension that the packet that reception receiving terminal is sent according to transmitting terminal is calculated and fed back.

Because channel has reciprocity, the characteristic of channel from transmitting terminal to receiving terminal, can according to from receiving terminal to The characteristic of channel of transmitting terminal is calculated.The packet that transmitting terminal is sent according to the receiving terminal received in the past, estimation channel is most Long time delay extends.Provided among such as IEEE802.11 standards, receiving terminal can send channel detection frame in the current channel （Null Data Packet, empty packet）, then transmitting terminal can calculate present channel by receiving channel detection frame Maximum delay extends.Or, receiving terminal can calculate maximum delay extension according to the packet received, and by maximum delay Extension is attached in specific order or frame head special domain and is sent to transmitting terminal, transmitting terminal is extended according to the maximum delay and determines The minimum value of first duration.

Specifically, calculating the method for maximum delay extension has many kinds, such as, according to the known pilot carried in packet Symbol or training sequence signal calculate maximum delay extension to calculate the frequency response of present channel according to the frequency response. Wherein, frequency pilot sign is to be carried on the known symbol on specific subcarrier, and training sequence is ad-hoc location in packet, generally It is the known OFDM symbol of original position.

Assuming that known pilot or training sequence signal are p, channel frequency response is H, and noise is N, then by current letter Reception signal after road is R=p*H+N, then H=R/p-N/p., can basis after the frequency response of present channel is calculated Quick inversefouriertransform obtains time series signal, and time series signal is stronger, and the interference that sub-carrier is caused is bigger, then The numerical value of the position of last larger time series signal can be defined as to maximum delay extension.Or, to training sequence Row carry out time correlation, i.e., enter line displacement to training sequence according to the time, and by local training sequence with including instruction after skew The reception signal for practicing sequence carries out correlation, because the interference that the bigger sub-carrier of correlation is caused is bigger, therefore, it can will be above The correlation of last position of predetermined threshold is defined as maximum delay extension.

Wherein, timing error duration is obtained, can be included：

Determine timing error duration；Or, receive the timing error duration that receiving terminal is determined and fed back.

Because timing error duration is typically the 5%~8% of the duration of OFDM symbol, when therefore, it can the timing error 5% etc. of the long duration for being defined as OFDM symbol, the present embodiment is not construed as limiting.Specifically, transmitting terminal can predefine one and determine When error duration, and by the timing error duration notify receiving terminal；Or, when receiving terminal can predefine a timing error It is long, and the timing error duration is fed back into transmitting terminal.

Step 302, transmitting terminal determines the first duration according to the duration T2 of minimum value T1 and protection interval so that the first duration Belong to [T1, T2）；

The waste of transfer resource can be caused in order to avoid transmitting cyclic prefix corresponding with protection interval duration, volume is consumed The problem of outer transmission energy, the first duration can be set to be less than the duration of protection interval, and the duration of protection interval is subtracted Residual time length after first duration is set to sky, refer to the schematic diagram of the previous OFDM symbol shown in Fig. 4, or, setting should Transmission consumption sends the relatively low signal of energy in residual time length, to save the transmission energy for sending protection interval.Such as, if first Duration accounts for the 20% of the duration of OFDM symbol, then one can save 10~20% transmission energy.

Further, it is determined that scope [T1, the T2 of the first duration）Afterwards, can be in [T1, T2）In one number of any selection Value is as the first duration, and the present embodiment is not construed as limiting to the method for selecting the first duration.

Step 303, transmitting terminal is according to the first duration and transmission signal generation previous OFDM symbol so that previous OFDM symbol Protection interval in cyclic prefix duration be equal to the first duration；

Further, before according to the first duration and transmission signal generation previous OFDM symbol, it can also include：

The Packet Error Ratio of at least one OFDM symbol before sending previous OFDM symbol is obtained, Packet Error Ratio is by least one OFDM symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

First duration is adjusted according to the size of Packet Error Ratio, the length of the size of Packet Error Ratio and the first duration is proportionate pass System so that the first duration after adjustment still falls within [T1, T2）.

In the present embodiment, can also according to the Packet Error Ratio of OFDM symbol feed back present channel the characteristic of channel, and according to work as The characteristic of channel of preceding channel adjusts the first duration.Such as, time threshold and adjustment thresholding can be pre-set, if then Packet Error Ratio is low Time threshold is reached in the time of adjustment thresholding, then reduces the length of the first duration, the numeral letter of pre- fixed step size can be such as reduced Number sampling point etc..Preferably, thresholding is lower, time threshold is longer for adjustment, then it is bigger to preset step-length, to show current channel characteristic Better.Furthermore it is also possible at least one time threshold, at least one adjustment thresholding and at least one default step-length are set, and really Surely step-length and time threshold are preset and adjusts the corresponding relation of thresholding, so that the adjustment thresholding that is less than according to Packet Error Ratio and low The default step-length for determining to need to adjust in the time of adjustment thresholding.

Preferably, the first duration adjusted according to Packet Error Ratio still falls within [T1, T2）, to save extra transmission energy, And the interference between subcarrier is reduced, wherein, T1 is that maximum delay extends or timing error duration or maximum delay extension and timing Higher value in error duration.Certainly, if the first duration is equal to after T1, the characteristic of channel is good, then when can continue to reduce first Long, until first duration reaches the minimum value pre-set, such as 0, i.e. protection interval are set to sky, and the present embodiment is not limited It is fixed.

Wherein, the Packet Error Ratio of at least one OFDM symbol before sending previous OFDM symbol is obtained, can be included：

Calculate Packet Error Ratio；Or, receive the Packet Error Ratio that receiving terminal is calculated and fed back.

Specifically, Packet Error Ratio can transmitting terminal record be sent to receiving terminal data packet retransmission or send fail Probability；Or, the Packet Error Ratio recorded by receiving terminal, receiving terminal by Packet Error Ratio be attached to by specifically order or frame head special domain in Transmitting terminal is fed back to, the present embodiment is not construed as limiting.

Step 304, transmitting terminal sends previous OFDM symbol to receiving terminal；

Step 305, the previous OFDM symbol that receiving terminal receiving end/sending end is sent, the previous OFDM symbol by the first duration and Signal generation is transmitted, first duration is determined by preparatory condition so that the first duration is less than between the protection in previous OFDM symbol Every duration and previous OFDM symbol protection interval in cyclic prefix duration be equal to the first duration；

In the present embodiment, before the previous OFDM symbol that receiving end/sending end is sent, it can also include：

The packet that receiving end/sending end is sent, and extended according to the maximum delay of packet calculating present channel；

The maximum delay extension that calculating is obtained feeds back to transmitting terminal.

Or, before the previous OFDM symbol that receiving end/sending end is sent, it can also include：

The timing error duration of previous OFDM symbol is determined, a length of receiving terminal processing previous OFDM symbol during timing error When, according to the duration of the period for the original position biased forwards that signal is transmitted in the previous OFDM symbol of determination；

Timing error duration after determination is fed back into transmitting terminal.

At least one OFDM symbol that receiving end/sending end is sent, and Packet Error Ratio is calculated according at least one OFDM symbol；

Packet Error Ratio is fed back into transmitting terminal.

Wherein, calculate maximum delay extension and determine that the flow of timing error duration refers to the description in step 301, calculate The flow of Packet Error Ratio refers to the description in step 303, does not repeat herein.

Step 306, receiving terminal is handled previous OFDM symbol.

In summary, data transmission method provided in an embodiment of the present invention, by determining the first duration according to preparatory condition, First duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol；According to first duration and Transmit previous OFDM symbol described in signal generation so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol Equal to first duration；The previous OFDM symbol is sent to receiving terminal, transmission is solved equal with protection interval duration The cyclic prefix of duration wastes transfer resource, the problem of consuming extra transmission energy, has reached and has saved transmission energy Effect.In addition, the Packet Error Ratio by obtaining at least one OFDM symbol before sending the previous OFDM symbol；According to described The size of Packet Error Ratio adjusts first duration, can be by Packet Error Ratio feedback channel characteristic, and solving can not be special according to channel Property the transmitting efficiency that causes of the first duration of adjustment it is low the problem of, reached the effect for improving transmitting efficiency.

Embodiment three

Fig. 5 is refer to, the structural framing figure of the data transmission system provided it illustrates the embodiment of the present invention three, the data Transmission system can include transmitting terminal and receiving terminal；Transmitting terminal can include：First determining module 510, generation module 520 and hair Send module 530；Receiving terminal can include：Receiving module 610 and processing module 620.The data transmission system, can include：

First determining module 510, for determining the first duration according to preparatory condition, first duration is accorded with less than current OFDM The duration of protection interval in number；

Generation module 520, the first duration and transmission signal generation for being determined according to the first determining module 510 is current OFDM symbol so that the duration of the cyclic prefix in the protection interval of previous OFDM symbol is equal to the first duration；

Sending module 530, for sending the previous OFDM symbol that generation module 520 is generated to receiving terminal；

Receiving module 610, the previous OFDM symbol sent for receiving end/sending end, previous OFDM symbol by the first duration and Signal generation is transmitted, first duration is determined by preparatory condition so that the first duration is less than between the protection in previous OFDM symbol Every duration and previous OFDM symbol protection interval in cyclic prefix duration be equal to the first duration；

Processing module 620, for handling the previous OFDM symbol that receiving module 610 is received.

In summary, data transmission system provided in an embodiment of the present invention, by determining the first duration according to preparatory condition, First duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol；According to first duration and Transmit previous OFDM symbol described in signal generation so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol Equal to first duration；The previous OFDM symbol is sent to receiving terminal, transmission is solved equal with protection interval duration The cyclic prefix of duration wastes transfer resource, the problem of consuming extra transmission energy, has reached and has saved transmission energy Effect.

Example IV

Fig. 6 is refer to, the structural framing figure of the data transmission system provided it illustrates the embodiment of the present invention four, the data Transmission system can include transmitting terminal and receiving terminal；Transmitting terminal can include：First determining module 510, generation module 520 and hair Send module 530；Receiving terminal can include：Receiving module 610 and processing module 620.The data transmission system, can include：

Sending module 530, the previous OFDM symbol for sending generation module generation to receiving terminal；

Further, the first determining module 510, can include：

First determining unit 501, the minimum value T1 for determining the first duration according to preparatory condition；

Second determining unit 502, for the minimum value T1 and the duration of protection interval determined according to the first determining unit 501 T2 determines the first duration so that the first duration belongs to [T1, T2）；

Preparatory condition is included in the maximum delay extension of present channel and the timing error duration of previous OFDM symbol extremely Few one kind, during timing error during a length of receiving terminal processing previous OFDM symbol, believes according to being transmitted in the previous OFDM symbol of determination Number original position biased forwards period duration.

Further, the first determining unit 501, can include：

If the preparatory condition only maximum delay including present channel extends, first obtains subelement 501A, for obtaining The maximum delay extension of present channel；First determination subelement 501B, for the first acquisition subelement 501A to be got most Long time delay extension is defined as minimum value T1；Or,

If preparatory condition only includes timing error duration, second obtains subelement 501C, for obtaining during timing error It is long；Second determination subelement 501D, for the second acquisition subelement 501C timing error durations got to be defined as into minimum Value T1；Or,

If preparatory condition includes maximum delay extension and the timing error duration of present channel, first obtains subelement 501A, the maximum delay for obtaining present channel extends；Second obtains subelement 501C, for obtaining timing error duration； 3rd determination subelement 501E, it is single for the first acquisition subelement 501A maximum delay extensions got and second to be obtained into son A larger value is defined as minimum value T1 in the timing error duration that first 501C is got.

Further, first subelement 501A is obtained, the packet for being fed back according to receiving terminal calculates maximum delay and expanded Exhibition；Or,

Further, receiving terminal can also include：First computing module 630, for the receiving end/sending end of receiving module 610 hair Before the previous OFDM symbol sent, the packet that receiving end/sending end is sent, and when calculating the maximum of present channel according to packet Prolong extension；First feedback module 640, transmission is fed back to for the first computing module 630 to be calculated into the extension of obtained maximum delay End；Accordingly, first subelement 501A is obtained, calculates and feed back for receiving packet that receiving terminal is sent according to transmitting terminal Maximum delay extends.

Further, second subelement 501C is obtained, for determining timing error duration；Or,

Receiving terminal can also include：Second determining module 650, for the current of the receiving end/sending end of receiving module 610 transmission Before OFDM symbol, the timing error duration of previous OFDM symbol is determined, a length of receiving terminal handles current OFDM during timing error During symbol, according to the duration of the period for the original position biased forwards that signal is transmitted in the previous OFDM symbol of determination；Second Feedback module 660, transmitting terminal is fed back to for the timing error duration after the second determining module 650 is determined；Accordingly, second Subelement 501C is obtained, for receiving the timing error duration that receiving terminal is determined and fed back.

Further, transmitting terminal can also include：

Acquisition module 540, for generation module 520 according to the first duration and transmission signal generation previous OFDM symbol it Before, the Packet Error Ratio of at least one OFDM symbol before sending previous OFDM symbol is obtained, Packet Error Ratio is by least one OFDM Symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

Adjusting module 550, the size of the Packet Error Ratio for being got according to acquisition module 540 adjusts the first duration, wraps by mistake The size of rate and the length correlation of the first duration so that the first duration after adjustment still falls within [T1, T2）.

Further, acquisition module 550, for calculating Packet Error Ratio；Or,

Receiving terminal can also include：Second computing module 670, for the current of the receiving end/sending end of receiving module 610 transmission Before OFDM symbol, at least one OFDM symbol that receiving end/sending end is sent, and bag by mistake is calculated according at least one OFDM symbol Rate；3rd feedback module 680, transmitting terminal is fed back to for the second computing module 670 to be calculated into obtained Packet Error Ratio；Accordingly, Acquisition module 550, for receiving the Packet Error Ratio that receiving terminal is calculated and fed back.

In summary, data transmission system provided in an embodiment of the present invention, by determining the first duration according to preparatory condition, First duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol；According to first duration and Transmit previous OFDM symbol described in signal generation so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol Equal to first duration；The previous OFDM symbol is sent to receiving terminal, transmission is solved equal with protection interval duration The cyclic prefix of duration wastes transfer resource, the problem of consuming extra transmission energy, has reached and has saved transmission energy Effect.In addition, the Packet Error Ratio by obtaining at least one OFDM symbol before sending the previous OFDM symbol；According to described The size of Packet Error Ratio adjusts first duration, can be by Packet Error Ratio feedback channel characteristic, and solving can not be special according to channel Property the transmitting efficiency that causes of the first duration of adjustment it is low the problem of, reached the effect for improving transmitting efficiency.

Embodiment five

Fig. 7 is refer to, the structural framing figure of the data transmission system provided it illustrates the embodiment of the present invention five, the data Transmission system can include transmitting terminal and receiving terminal；Transmitting terminal can include：First receiver 710, first processor 720 and One emitter 730；Receiving terminal can include：Second receiver 810 and second processor 820.The data transmission system, can be wrapped Include：

First receiver 710, for receiving transmission signal；

First processor 720, for determining the first duration according to preparatory condition, first duration is less than previous OFDM symbol In protection interval duration；The current OFDM of transmission signal generation received according to first duration and the first receiver 710 Symbol so that the duration of the cyclic prefix in the protection interval of previous OFDM symbol is equal to the first duration；

First emitter 730, for sending the previous OFDM symbol that first processor 720 is generated to receiving terminal；

Second receiver 810, the previous OFDM symbol sent for receiving end/sending end, previous OFDM symbol is by the first duration With transmission signal generation, first duration is determined by preparatory condition so that the first duration is less than the protection in previous OFDM symbol The duration of the duration at interval and the cyclic prefix in the protection interval of previous OFDM symbol is equal to the first duration；

Second processor 820, for handling the previous OFDM symbol that the second receiver 810 is received.

Embodiment six

Fig. 8 is refer to, the structural framing figure of the data transmission system provided it illustrates the embodiment of the present invention six, the data Transmission system can include transmitting terminal and receiving terminal；Transmitting terminal can include：First receiver 710, first processor 720 and One emitter 730；Receiving terminal can include：Second receiver 810, the emitter 830 of second processor 820 and the 3rd.The data Transmission system, can include：

First receiver 710, for receiving transmission signal；

Further, first processor 720, the minimum value T1 for determining the first duration according to preparatory condition；According to true Fixed minimum value T1 and the duration T2 of protection interval determine the first duration so that the first duration belongs to [T1, T2）；Preparatory condition bag Include at least one of the maximum delay extension of present channel and the timing error duration of previous OFDM symbol, timing error duration When handling previous OFDM symbol for receiving terminal, according to the original position biased forwards that signal is transmitted in the previous OFDM symbol of determination Period duration.

Further, first processor 720, extend if being additionally operable to the preparatory condition only maximum delay including present channel, Then obtain the maximum delay extension of present channel；The maximum delay got extension is defined as minimum value T1；Or, if default Condition only includes timing error duration, then obtains timing error duration；The timing error duration got is defined as minimum value T1；Or, if preparatory condition includes maximum delay extension and the timing error duration of present channel, obtain present channel most Long time delay extends；Obtain timing error duration；By the maximum delay got extend and the timing error duration that gets in compared with A big value is defined as minimum value T1.

Further, first processor 720, the packet for being fed back according to receiving terminal calculates maximum delay extension；Or Person,

Accordingly, before the second receiver 810, the previous OFDM symbol sent for receiving end/sending end, receiving end/sending end The packet of transmission；Second processor 820, the maximum delay for calculating present channel according to packet extends；Receiving terminal is also It can include：Second emitter 830, transmitting terminal is fed back to for second processor 820 to be calculated into the extension of obtained maximum delay； Accordingly, the first receiver 710, for receiving the maximum delay that the packet that receiving terminal is sent according to transmitting terminal is calculated and fed back Extension.

Further, first processor 720, for determining timing error duration；Or,

Accordingly, second processor 820, for the receiving end/sending end of the second receiver 810 send previous OFDM symbol it Before, the timing error duration of previous OFDM symbol is determined, during timing error during a length of receiving terminal processing previous OFDM symbol, according to The duration of the period of the original position biased forwards of signal is transmitted in the previous OFDM symbol of determination；Second emitter 830, is used Timing error duration after second processor 820 is determined feeds back to transmitting terminal；Accordingly, the first receiver 710, for connecing Receive the timing error duration that receiving terminal is determined and fed back.

Further, first processor 720, for according to the first duration and transmission signal generation previous OFDM symbol it Before, the Packet Error Ratio of at least one OFDM symbol before sending previous OFDM symbol is obtained, Packet Error Ratio is by least one OFDM Symbol is packaged into the ratio of the packet of bust this and total data bag after packet；According to the big ditty of the Packet Error Ratio got Whole first duration, the size of Packet Error Ratio and the length correlation of the first duration so that the first duration after adjustment is still Belong to [T1, T2）.

Further, first processor 720, for calculating Packet Error Ratio；Or,

Accordingly, before the second receiver 810, the previous OFDM symbol sent for receiving end/sending end, receiving end/sending end At least one OFDM symbol sent, second processor 820, for calculating Packet Error Ratio according at least one OFDM symbol；Second Emitter 830, transmitting terminal is fed back to for second processor 820 to be calculated into obtained Packet Error Ratio；Accordingly, the first receiver 710, for receiving the Packet Error Ratio that receiving terminal is calculated and fed back.

Embodiment seven

Fig. 9 is refer to, the structural framing figure of the data transmission system provided it illustrates the embodiment of the present invention seven, the data Transmission system can include transmitting terminal 910 and receiving terminal 920.

Wherein, transmitting terminal 910 can be the transmitting terminal in embodiment three, and receiving terminal 920 can be connecing in embodiment three Receiving end；Or,

Transmitting terminal 910 can be the transmitting terminal in example IV, and receiving terminal 920 can be the receiving terminal in example IV； Or,

Transmitting terminal 910 can be the transmitting terminal in embodiment five, and receiving terminal 920 can be the receiving terminal in embodiment five； Or,

Transmitting terminal 910 can be the transmitting terminal in embodiment six, and receiving terminal 920 can be the receiving terminal in embodiment six.

It should be noted that：Transmitting terminal, receiving terminal and the data transmission system that above-described embodiment is provided are carrying out data biography , can be as needed and by above-mentioned functions only with the division progress of above-mentioned each functional module for example, in practical application when defeated Distribute and completed by different functional modules, i.e., the internal structure of transmitting terminal, receiving terminal and data transmission system is divided into difference Functional module, to complete all or part of function described above.In addition, the transmitting terminal of above-described embodiment offer, reception End and data transmission system belong to same design with data transmission method embodiment, and it implements process and refers to method implementation Example, is repeated no more here.

The embodiments of the present invention are for illustration only, and the quality of embodiment is not represented.

One of ordinary skill in the art will appreciate that realizing that all or part of step of above-described embodiment can be by hardware To complete, the hardware of correlation can also be instructed to complete by program, described program can be stored in a kind of computer-readable In storage medium, storage medium mentioned above can be read-only storage, disk or CD etc..

The foregoing is only presently preferred embodiments of the present invention, be not intended to limit the invention, it is all the present invention spirit and Within principle, any modification, equivalent substitution and improvements made etc. should be included in the scope of the protection.

Claims

1. a kind of data transmission method, it is characterised in that methods described includes：

First duration is determined according to preparatory condition, first duration is less than the protection in current orthogonal frequency division multiplex OFDM symbol The duration at interval, the preparatory condition includes maximum delay extension and the timing error of the previous OFDM symbol of present channel At least one of duration；

The previous OFDM symbol according to first duration and transmission signal generation so that the protection of the previous OFDM symbol The duration of cyclic prefix in interval is equal to first duration；

The previous OFDM symbol is sent to receiving terminal.

2. data transmission method according to claim 1, it is characterised in that described when determining first according to preparatory condition Long, first duration is less than the duration of the protection interval in current orthogonal frequency division multiplex OFDM symbol, including：

First duration is determined according to the minimum value T1 and the protection interval duration T2 so that the first duration category In [T1, T2)；

When a length of receiving terminal handles the previous OFDM symbol during timing error, according to the current OFDM of determination The duration of the period of the original position biased forwards of signal is transmitted in symbol.

3. data transmission method according to claim 2, it is characterised in that described according to being determined the preparatory condition The minimum value T1 of first duration, including：

If the preparatory condition only maximum delay including the present channel extends, when obtaining the maximum of the present channel Prolong extension, the maximum delay got extension is defined as the minimum value T1；Or,

If the preparatory condition only includes the timing error duration, the timing error duration is obtained, by the institute got State timing error duration and be defined as the minimum value T1；Or,

If the preparatory condition includes the maximum delay extension of the present channel and the timing error duration, obtain described The maximum delay extension of present channel, and obtain the timing error duration；Maximum delay extension and the timing are missed A larger value is defined as the minimum value T1 in poor duration.

4. data transmission method according to claim 3, it is characterised in that during the maximum of the acquisition present channel Prolong extension, including：

5. data transmission method according to claim 3, it is characterised in that the acquisition timing error duration, bag Include：

6. according to any described data transmission method of claim 2 to 5, it is characterised in that described according to first duration Before previous OFDM symbol described in transmission signal generation, in addition to：

The Packet Error Ratio of at least one OFDM symbol before sending the previous OFDM symbol is obtained, the Packet Error Ratio is will be described At least one OFDM symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

First duration, the size of the Packet Error Ratio and the length of first duration are adjusted according to the size of the Packet Error Ratio Correlation so that first duration after adjustment still fall within [T1, T2).

7. data transmission method according to claim 6, it is characterised in that the acquisition sends the previous OFDM symbol The Packet Error Ratio of at least one OFDM symbol before, including：

8. a kind of data transmission method, it is characterised in that methods described includes：

The current orthogonal frequency division multiplex OFDM symbol that receiving end/sending end is sent, the previous OFDM symbol is by the first duration and transmission Signal generation, first duration is determined by preparatory condition so that first duration is less than in the previous OFDM symbol The duration of cyclic prefix in the protection interval of the duration of protection interval and the previous OFDM symbol is equal to first duration, The preparatory condition is included in the maximum delay extension of present channel and the timing error duration of the previous OFDM symbol extremely Few one kind；

The previous OFDM symbol is handled.

9. data transmission method according to claim 8, it is characterised in that the current orthogonal that the receiving end/sending end is sent Before frequency division multiplex OFDM symbol, in addition to：

The packet that the transmitting terminal is sent is received, and the maximum delay for calculating present channel according to the packet extends；

10. data transmission method according to claim 8, it is characterised in that the receiving end/sending end send it is current just Before friendship frequency division multiplex OFDM symbol, in addition to：

The timing error duration of the previous OFDM symbol is determined, a length of receiving terminal processing is described current during the timing error During OFDM symbol, according in the previous OFDM symbol of determination transmit signal original position biased forwards period when It is long；

11. data transmission method according to claim 8, it is characterised in that the receiving end/sending end send it is current just Before friendship frequency division multiplex OFDM symbol, in addition to：

At least one OFDM symbol that the transmitting terminal is sent is received, and bag by mistake is calculated according at least one described OFDM symbol Rate；

The Packet Error Ratio is fed back into the transmitting terminal.

12. a kind of transmitting terminal, it is characterised in that the transmitting terminal includes：

First determining module, for determining the first duration according to preparatory condition, first duration is multiple less than current orthogonal frequency division With the duration of the protection interval in OFDM symbol, the maximum delay that the preparatory condition includes present channel extends and described current At least one of timing error duration of OFDM symbol；

Generation module, for current described in first duration that is determined according to first determining module and transmission signal generation OFDM symbol so that the duration of the cyclic prefix in the protection interval of the previous OFDM symbol is equal to first duration；

13. transmitting terminal according to claim 12, it is characterised in that first determining module, including：

Second determining unit, for the minimum value T1 that is determined according to first determining unit and the protection interval when Long T2 determines first duration so that first duration belong to [T1, T2)；

14. transmitting terminal according to claim 13, it is characterised in that first determining unit, including：

If the preparatory condition only maximum delay including the present channel extends, first obtains subelement, for obtaining The maximum delay extension of the present channel；First determination subelement, for the institute for getting the described first acquisition subelement State maximum delay extension and be defined as the minimum value T1；Or,

If the preparatory condition only includes the timing error duration, second obtains subelement, is missed for obtaining the timing Poor duration；Second determination subelement, the timing error duration for the described second acquisition subelement to be got is defined as The minimum value T1；Or,

If the preparatory condition includes the maximum delay extension of the present channel and the timing error duration, first obtains Subelement, the maximum delay for obtaining the present channel extends；Second obtains subelement, for obtaining the timing error Duration；3rd determination subelement, for the maximum delay extension and described for getting the described first acquisition subelement A larger value is defined as the minimum value T1 in the timing error duration that two acquisition subelements are got.

15. transmitting terminal according to claim 14, it is characterised in that described first obtains subelement, for according to described The packet of receiving terminal feedback calculates the maximum delay extension；Or, receive the number that the receiving terminal is sent according to transmitting terminal The maximum delay extension for calculating and feeding back according to bag.

16. transmitting terminal according to claim 14, it is characterised in that described second obtains subelement, described for determining Timing error duration；Or, receive the timing error duration that the receiving terminal is determined and fed back.

17. according to any described transmitting terminal of claim 13 to 16, it is characterised in that the transmitting terminal also includes：

Acquisition module, for the generation module according to first duration and transmission signal generation described in previous OFDM symbol it Before, the Packet Error Ratio of at least one OFDM symbol before sending the previous OFDM symbol is obtained, the Packet Error Ratio is will be described At least one OFDM symbol is packaged into the ratio of the packet of bust this and total data bag after packet；

Adjusting module, the size of the Packet Error Ratio for being got according to the acquisition module adjusts first duration, institute State the size of Packet Error Ratio and the length correlation of first duration so that first duration after adjustment still belongs to In [T1, T2).

18. transmitting terminal according to claim 17, it is characterised in that the acquisition module, for calculating the Packet Error Ratio； Or, receive the Packet Error Ratio that the receiving terminal is calculated and fed back.

19. a kind of receiving terminal, it is characterised in that the receiving terminal includes：

Receiving module, for receiving end/sending end send current orthogonal frequency division multiplex OFDM symbol, the previous OFDM symbol by First duration and transmission signal generation, first duration are determined by preparatory condition so that first duration is less than described work as Duration of cyclic prefix in the protection interval of the duration of protection interval in preceding OFDM symbol and the previous OFDM symbol etc. In first duration, the preparatory condition includes the maximum delay extension and the timing of the previous OFDM symbol of present channel At least one of error duration；

20. receiving terminal according to claim 19, it is characterised in that the receiving terminal also includes：

First computing module, for the receiving module receiving end/sending end send current orthogonal frequency division multiplex OFDM symbol it Before, the packet that the transmitting terminal is sent is received, and the maximum delay for calculating present channel according to the packet extends；

First feedback module, the hair is fed back to for first computing module to be calculated into the extension of the obtained maximum delay Sending end.

21. receiving terminal according to claim 19, it is characterised in that the receiving terminal also includes：

Second determining module, for the receiving module receiving end/sending end send current orthogonal frequency division multiplex OFDM symbol it Before, the timing error duration of the previous OFDM symbol is determined, a length of receiving terminal processing is described current during the timing error During OFDM symbol, according in the previous OFDM symbol of determination transmit signal original position biased forwards period when It is long；

Second feedback module, the transmission is fed back to for the timing error duration after second determining module is determined End.

22. receiving terminal according to claim 19, it is characterised in that the receiving terminal also includes：

Second computing module, for the receiving module receiving end/sending end send current orthogonal frequency division multiplex OFDM symbol it Before, at least one OFDM symbol that the transmitting terminal is sent is received, and Packet Error Ratio is calculated according at least one described OFDM symbol；

3rd feedback module, the transmitting terminal is fed back to for second computing module to be calculated into the obtained Packet Error Ratio.

23. a kind of data transmission system, it is characterised in that the system includes：Hair as described in claim 12 to 18 is any Sending end and the receiving terminal as described in claim 19 to 22 is any.