CN101272234B - Data transmission method and system for OFDM system - Google Patents

Abstract

The invention discloses a data transmission method and system used for an OFDM system; wherein, the method comprises the following steps: step S102, a transmitting end marking sub-wave carriers of each OFDM sign into 0 to NFFT-1; wherein, NGUARD sub-wave carriers in the NFFT sub-wave carriers are protective sub-wave carriers; taking the sub-wave carriers KOFFSET to (NGUARD, LEFT-1+KOFFSET) mod NFFT, the (NFFT2+KOFFSET)modNFFT sub-wave carriers, and the sub-wave carriers (NGUARD, RIGHT+KOFFSET)modNFFT to the sub-wave carriers (NFFT-1+KOFFSET)modNFFT as the protective sub-wave carriers; NGUARD, LEFT = NGUARD2-1; NGUARD, RIGHT = NFFT-NGUARD2; taking all the sub-wave carriers not belonging to the protective sub-wave carriers as useful sub-wave carriers; step S104, the transmitting end transmitting the data to the receiving end on the useful sub-wave carriers; step S106, the receiving end receiving the data transmitted by the useful sub-wave carriers according to the distribution of the sub-wave carriers. The invention can define the numbers of the optimized useful sub-wave carriers and the numbers of the protective sub-wave carriers as well as appoint a smallest resource distribution unit under the situation of various bandwidth collocations.

Description

The data transmission method and the system that are used for ofdm system

Technical field

The present invention relates to the communications field, relate in particular to a kind of data transmission method that is used for ofdm system.

Background technology

OFDM (Orthogonal Frequency Division Multiplexing, OFDM) basic thought of technology is in frequency domain given channel to be divided into many orthogonal sub-channels, on each subchannel, use a subcarrier to modulate, and each subcarrier parallel transmission.Although total channel is a non-flat forms, has frequency selectivity, but each subchannel is a relatively flat, what carry out on each subchannel is narrow band transmission, signal bandwidth is less than the respective bandwidth of channel, therefore the interference between the erasure signal waveform greatly, and because the introducing of Cyclic Prefix, further strengthened the ability of the anti-intersymbol interference of system (ISI).OFDM is that its allows subcarrier spectrum to overlap with respect to the difference of general multi-carrier transmission, as long as satisfy between subcarrier mutually orthogonally, then can isolate data-signal from overlapping subcarrier.Because OFDM allows subcarrier spectrum overlapping, its spectrum efficiency improves greatly, thereby is a kind of modulation system efficiently.

The OFDM technology relies on it intrinsic the stronger resistance of time delay expansion and higher spectrum efficiency two big advantages are become the focus of research rapidly and adopted by a plurality of international norms.For example, Ou Zhou digital audio broadcasting (DAB) and digital video broadcasting terrestrial transmission mode (DVB-T) all are based on the OFDM technology.In addition, the expansion of the IEEE802.11a standard of the 5GHZ ghz area of Ou Zhou HIPERLAN2 standard and North America also is based on the OFDM technology.A kind of wise selection that OFDM is considered to provide high-speed mobile to use, mobile radio communication system of future generation or the 4th generation wireless telecommunication system all will be based on the OFDM technology.

But it seems from the spectrum allocation may of various countries, in wireless system of future generation (UMB, LTE, Wimax, IMT-Advanced) to seek the spectrum allocation may of the unified bandwidth in the whole world be a very thing of difficulty, and how to utilize fragmentary frequency spectrum also be a very important problem.These problems are all brought very large constraint and challenge to the design of wireless telecommunication system of future generation.Extendible OFDMA technology can be improved this problem on certain degree.So-called extendible OFDMA technology is meant can support various number of subcarriers, but subcarrier spacing is constant, the OFDMA technology that signal bandwidth is directly proportional with number of subcarriers.Use this technology, system can be in mobile environment the variation of flexible adaptation channel width.

In ofdm system because the consideration that frequency band is isolated, at some subcarriers on both sides as the protection subcarrier; The quantity of useful subcarrier changes according to the quantity of protecting subcarrier under different bandwidth like this; simultaneously because the consideration of resource allocation; in wireless system design; can set the least unit of a resource allocation; and the number of available subcarrier must be the integral multiple of the shared subcarrier of resource allocation unit least unit under different bandwidth, and the required subcarrier of least unit that therefore how to design suitable protection number of sub carrier wave and resource allocation under different bandwidth is a challenging problem.

Samsung is in the patent " apparatus and method of dividing frequency in OFDM mobile communication system " of CN200510113210 at application number, proposes a kind of apparatus and method of giving subscriber equipment (UE) dividing frequency resource in OFDM (OFDM) mobile communication system.Wherein, the base station receives the feedback information that comprises mobility information at least from UE, and determine that according to mobility information it still is the low speed group that UE belongs to high-speed set, if UE belongs to high-speed set, then the base station is a UE dividing frequency resource according to the open loop solution, if and UE belongs to the low speed group, then the base station is a UE dividing frequency resource according to the closed loop solution, and uses the frequency resource of distributing to send data as UE.Yet how this patent does not have to solve at the give a definition available subcarrier optimized of the situation of various band width configuration distributes and does not specify minimum resource allocation unit.

Summary of the invention

At problems of the prior art; the purpose of this invention is to provide a kind of data transmission method and system that is used for ofdm system, the present invention can be in available subcarrier number and protection number of sub carrier wave and the appointment minimum resource allocation unit that the situation of various band width configuration is given a definition and optimized.

Be without loss of generality, make X _kBe the complex symbol on k the subcarrier of an OFDM symbol, k is to N from 0 _FFT-1, so the output of IFFT computing should for

$X\left(t\right)=\frac{1}{\sqrt{N_{\mathrm{FFT}}}}\underset{k=0}{\overset{N_{\mathrm{FFT}}-1}{\mathrm{\Σ}}}{X}_k{e}^{j2\mathrm{\π}(k-k_{\mathrm{OFFSET}}-N_{\mathrm{FFT}}/2)(t-T_{\mathrm{CP}}-T_{\mathrm{START}})/\left(N_{\mathrm{FFT}}{T}_{\mathrm{CHIP}}\right)},---\left(1\right)$

T wherein _STARTThe zero-time of representing this OFDM symbol, TCP represents the duration of the Cyclic Prefix of OFDM symbol, T _CHIPThe expression Chip time, K _OFFSETThe side-play amount of the subcarrier of expression IFFT.

For achieving the above object, the data transmission method that is used for ofdm system of the present invention may further comprise the steps: step S102, transmitting terminal is designated 0 to N with the subcarrier of each OFDM symbol _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is for the protection subcarrier, with subcarrier K _OFFSETTo subcarrier (N _{GUARD, LEFT}-1+K _OFFSET) mod N _FFT, (N _FFT/ 2+K _OFFSET) mod N _FFTSubcarrier and subcarrier (N _{GUARD, RIGHT}+ K _OFFSET) mod N _FFTTo subcarrier (N _FFT-1+K _OFFSET) mod N _FFTAs protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, (mod represents modulo operation), with all do not belong to protect subcarrier subcarrier as useful subcarrier; Step S104, transmitting terminal is sent to receiving terminal with data on useful subcarrier; And step S106, receiving terminal receives the data of transmitting by useful subcarrier according to the distribution of subcarrier.

The data transmission system that is used for ofdm system of the present invention comprises: data sending device is used for the subcarrier of each OFDM symbol is designated 0 to N _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is for the protection subcarrier, with subcarrier K _OFFSETTo subcarrier (N _{GUARD, LEFT}-1+K _OFFSET) mod N _FFT, (N _FFT/ 2+K _OFFSET) modN _FFTSubcarrier and subcarrier (N _{GUARD, RIGHT}+ K _OFFSET) mod N _FFTTo subcarrier (N _FFT-1+K _OFFSET) mod N _FFTAs protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier, data sending device is sent to data sink with data on useful subcarrier; And data sink, be used for receiving the data of transmitting by useful subcarrier according to the distribution of subcarrier.

Wherein, the sum of subcarrier is specified by the message of layer three; Do not have energy to be sent out on the protection subcarrier, the quantity of protection subcarrier and the bandwidth of ofdm system are proportional.

Wherein, be under the situation of 1.25M in the bandwidth of ofdm system, the quantity of protection subcarrier is 8; Bandwidth at ofdm system is under the situation of 2.5M, and the quantity of protection subcarrier is 16; Bandwidth at ofdm system is under the situation of 5M, and the quantity of protection subcarrier is 32; Bandwidth at ofdm system is under the situation of 10M, and the quantity of protection subcarrier is 64; And be under the situation of 20M in the bandwidth of ofdm system, the quantity of protection subcarrier is 128.

Wherein, be under the situation of 1.25M in the bandwidth of ofdm system, the shared sub-carrier number of the least unit of resource allocation is 8; Bandwidth at ofdm system is under the situation of 2.5M, and the shared sub-carrier number of the least unit of resource allocation is 8; Bandwidth at ofdm system is under the situation of 5M, and the shared sub-carrier number of the least unit of resource allocation is 16; Bandwidth at ofdm system is under the situation of 10M, and the shared sub-carrier number of the least unit of resource allocation is 16; And be under the situation of 20M in the bandwidth of ofdm system, the shared sub-carrier number of the least unit of resource allocation is 16.

Wherein, this data transmission method and device are applied to the ofdm system of following at least a bandwidth: 1.25M, 2.5M, 5M, 10M, 20M.

The invention provides a kind of data transmission method and system that is used for ofdm system, in the present invention, for different bandwidth, the number of protection subcarrier is proportional variation, makes to have identical spectrum efficiency under different bandwidth.In addition, the protection subcarrier not only depends on the subcarrier on frequency band both sides, and corresponding to that subcarrier of the centre of direct current subcarrier also as the protection subcarrier.Simultaneously, the different caused different control messages expense of the size of requirement of isolating at the balance frequency band and resource allocation least unit has provided the scheme of resource allocation least unit under the different bandwidth.

Description of drawings

Shuo Ming accompanying drawing is used to provide further understanding of the present invention herein, constitutes the application's a part, and illustrative examples of the present invention and explanation thereof are used to explain the present invention, do not constitute to improper qualification of the present invention, in the accompanying drawings:

Fig. 1 is the flow chart of the data transmission method that is used for ofdm system of embodiments of the invention;

Fig. 2 is the structural representation of the data transmission system that is used for ofdm system of embodiments of the invention; And

Fig. 3 works as K _OFFSET=0 o'clock subcarrier distribution scheme figure under different bandwidth according to an embodiment of the invention.

Embodiment

Below in conjunction with corresponding accompanying drawing and specific embodiment data transmission method and the system that is used for ofdm system of the present invention is described in detail.

For common ofdm system, the side-play amount K of the subcarrier of the IFFT in the formula (1) _OFFSETCan be taken as 0 is K _OFFSET=0.For describing simple meter, this embodiment is with K _OFFSET=0 is example.

Fig. 1 is the flow chart of the data transmission method that is used for ofdm system of embodiments of the invention.As shown in Figure 1, the data transmission method that is used for ofdm system of the present invention may further comprise the steps: step S102, transmitting terminal is designated 0 to N with the subcarrier of each OFDM symbol _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is the protection subcarrier, with subcarrier 0 to N _{GUARD, LEFT}-1, N _FFT/ 2 and subcarrier N _{GUARD, RIGHT}To subcarrier N _FFT-1 as protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier; Step S104, transmitting terminal is sent to receiving terminal with data on useful subcarrier; And step S106, receiving terminal receives the data of transmitting by useful subcarrier according to the distribution of subcarrier.

Fig. 2 is the structural representation of the data transmission system that is used for ofdm system of embodiments of the invention.As shown in Figure 2, the data transmission system that is used for ofdm system of embodiments of the invention comprises: data sending device 202 is used for the subcarrier of each OFDM symbol is designated 0 to N _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is the protection subcarrier, with subcarrier 0 to N _{GUARD, LEFT}-1, N _FFT/ 2 subcarriers and subcarrier N _{GUARD, RIGHT}To subcarrier N _FFT-1 as protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier, data sending device is sent to data sink with data on useful subcarrier; And data sink 204, be used for receiving the data of transmitting by useful subcarrier according to the distribution of subcarrier.

In said method and system, the sum of subcarrier is specified by the message of layer three; Do not have energy to be sent out on the protection subcarrier, the quantity of protection subcarrier and the bandwidth of ofdm system are proportional.

Wherein, be under the situation of 1.25M in the bandwidth of ofdm system, the quantity of protection subcarrier is 8; Bandwidth at ofdm system is under the situation of 2.5M, and the quantity of protection subcarrier is 16; Bandwidth at ofdm system is under the situation of 5M, and the quantity of protection subcarrier is 32; Bandwidth at ofdm system is under the situation of 10M, and the quantity of protection subcarrier is 64; And be under the situation of 20M in the bandwidth of ofdm system, the quantity of protection subcarrier is 128.

In addition, be under the situation of 1.25M in the bandwidth of ofdm system, the shared sub-carrier number of the least unit of resource allocation is 8; Bandwidth at ofdm system is under the situation of 2.5M, and the shared sub-carrier number of the least unit of resource allocation is 8; Bandwidth at ofdm system is under the situation of 5M, and the shared sub-carrier number of the least unit of resource allocation is 16; Bandwidth at ofdm system is under the situation of 10M, and the shared sub-carrier number of the least unit of resource allocation is 16; And be under the situation of 20M in the bandwidth of ofdm system, the shared sub-carrier number of the least unit of resource allocation is 16.

This data transmission method and system applies are in the ofdm system of following at least a bandwidth: 1.25M, 2.5M, 5M, 10M, 20M.

Technical scheme of the present invention is the compromise consideration of different caused different control messages expenses of the size of the requirement isolated of frequency band and resource allocation least unit, and it can be applied to 1.25M in the 20M scope in the extendible ofdm system better.

The subcarrier of each OFDM symbol is with 0 to N _FFT-1 sign, wherein the total number of sub-carriers N under the different bandwidth _FFTValue specify by the message of layer three.

At all N _FFTIn the individual subcarrier, N is arranged _GuardIndividual subcarrier is the protection subcarrier, does not have energy to be sent out on these protection subcarriers, (what place on it in other words is modulation complex symbol (0,0)).

Subcarrier 0 to subcarrier N _{GUARD, LEFT}-1 and N _FFT/ 2 subcarriers and subcarrier N _{GUARD, RIGHT}To subcarrier N _FFTThe-1st, the protection subcarrier; N wherein _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2.

Any subcarrier of protecting subcarrier that do not belong to is useful subcarrier.

Fig. 3 is the subcarrier distribution scheme figure under different bandwidth according to the embodiment of the invention, as shown in Figure 3, and for the number N of its protection subcarrier of the ofdm system of 1.25M, 2.5M, 5M, 10M, 20M bandwidth _GuardAlso be proportional, be respectively 8,16,32,64,128, as shown in table 1, like this for different bandwidth, there is same spectrum efficiency in system.

Table 1: the number of the protection subcarrier of the ofdm system of different bandwidth

Bandwidth	1.25M	2.5M	5M	10M	20M
						The number of protection subcarrier	?8	16	32	64	128

The least unit of system definition resource allocation is N _{SubcarriesPerBlock}* N _{SymbolsPerBlock}Two-dimentional time-frequency piece, N wherein _{SymbolsPerBlock}Represent the length of each two-dimentional time-frequency piece on time shaft, promptly what OFDM symbol this time-frequency piece take, and this value can adopt the value of acquiescence or specify by the message of layer three; N wherein _{SubcarriesPerBlock}Represent the length of each two-dimentional time-frequency piece on frequency axis, promptly this time-frequency piece takies what subcarrier, N _{SubcarriesPerBlock}Promptly can also can on frequency axis, choose (resource allocation that is distribution) in the compartment of terrain choosing (resource allocation that is localization) on the frequency axis continuously.Consider the difference and the N of the expense of the control messages that resource allocation unit brings that difference is big or small _{SubcarriesPerBlock}Number must be the factor of total available subcarrier number, the number of the subcarrier that the least unit of every resource allocation of the best in the 1.25M-20M scope is shared should be for as shown in table 2:

Table 2: the number of the subcarrier that the least unit of every resource allocation is shared

Bandwidth	1.25M	2.5M	5M	10M	20M
						Shared sub-carrier number (the N of minimum assignable Resource Block SubcarriesPerBlock)	?8	?8	16	16	16

Those skilled in the art will readily understand additional advantages and modifications of the present invention.Therefore, above-mentioned at embodiment be described as the concrete Application Example of the present invention, the present invention aspect widely is not limited to the specific detail and the exemplary embodiments that illustrate and describe herein.Therefore, can under the condition that does not break away from by claim and the spirit or scope of the present invention that equivalent limited thereof, make various modifications.

Claims (16)

1. a data transmission method that is used for ofdm system is characterized in that, may further comprise the steps:

Step S102, transmitting terminal is designated 0 to N with the subcarrier of each OFDM symbol _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is for the protection subcarrier, with subcarrier K _OFFSETTo (N _{GUARD, LEFT}-1+K _OFFSET) modN _FFT, (N _FFT/ 2+K _OFFSET) mod N _FFTSubcarrier and subcarrier (N _{GUARD, RIGHT}+ K _OFFSET) mod N _FFTTo subcarrier (N _FFT-1+K _OFFSET) modN _FFTAs protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier;

Step S104, described transmitting terminal is sent to receiving terminal with data on described useful subcarrier; And

Step S106, described receiving terminal receives the data of transmitting by described useful subcarrier according to the distribution of described subcarrier.

2. data transmission method according to claim 1 is characterized in that the sum of described subcarrier is specified by the message of layer three.

3. data transmission method according to claim 1 is characterized in that, does not have energy to be sent out on described protection subcarrier.

4. data transmission method according to claim 1 is characterized in that described data transmission method is applied to the ofdm system of following at least a bandwidth: 1.25M, 2.5M, 5M, 10M, 20M.

5. data transmission method according to claim 4 is characterized in that, the quantity of described protection subcarrier and the bandwidth of described ofdm system are proportional.

6. data transmission method according to claim 5 is characterized in that:

Bandwidth at described ofdm system is under the situation of 1.25M, and the quantity of described protection subcarrier is 8;

Bandwidth at described ofdm system is under the situation of 2.5M, and the quantity of described protection subcarrier is 16;

Bandwidth at described ofdm system is under the situation of 5M, and the quantity of described protection subcarrier is 32;

Bandwidth at described ofdm system is under the situation of 10M, and the quantity of described protection subcarrier is 64; And

Bandwidth at described ofdm system is under the situation of 20M, and the quantity of described protection subcarrier is 128.

7. data transmission method according to claim 5 is characterized in that:

Bandwidth at described ofdm system is under the situation of 1.25M, and the shared sub-carrier number of the least unit of resource allocation is 8;

Bandwidth at described ofdm system is under the situation of 2.5M, and the shared sub-carrier number of the least unit of resource allocation is 8;

Bandwidth at described ofdm system is under the situation of 5M, and the shared sub-carrier number of the least unit of resource allocation is 16;

Bandwidth at described ofdm system is under the situation of 10M, and the shared sub-carrier number of the least unit of resource allocation is 16; And

Bandwidth at described ofdm system is under the situation of 20M, and the shared sub-carrier number of the least unit of resource allocation is 16.

8. data transmission method according to claim 1 is characterized in that, the side-play amount K of the subcarrier in the IFFT operation _OFFSETBeing taken as 0 is K _OFFSET=0; May further comprise the steps:

Step S102, transmitting terminal is designated 0 to N with the subcarrier of each OFDM symbol _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is the protection subcarrier, with subcarrier 0 to N _{GUARD, LEFT}-1, N _FFT/ 2 subcarriers and subcarrier N _{GUARD, RIGHT}To subcarrier N _FFT-1 as protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier;

Step S104, described transmitting terminal is sent to receiving terminal with data on described useful subcarrier; And

Step S106, described receiving terminal receives the data of transmitting by described useful subcarrier according to the distribution of described subcarrier.

9. data transmission system that is used for ofdm system is characterized in that comprising:

Data sending device is used for the subcarrier of each OFDM symbol is designated 0 to N _FFT-1, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is for the protection subcarrier, with subcarrier K _OFFSETTo (N _{GUARD, LEFT}-1+K _OFFSET) modN _FFT, N _FFT/ 2+K _OFFSET) mod N _FFTSubcarrier and (N _{GUARD, RIGHT}+ K _OFFSET) mod N _FFTTo subcarrier (N _FFT-1+K _OFFSET) modN _FFTAs protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier, described data sending device is sent to data sink with data on described useful subcarrier; And

Described data sink is used for receiving the data of transmitting by described useful subcarrier according to the distribution of described subcarrier.

10. data transmission system according to claim 9 is characterized in that the sum of described subcarrier is specified by the message of layer three.

11. data transmission system according to claim 9 is characterized in that, does not have energy to be sent out on described protection subcarrier.

12. data transmission system according to claim 9 is characterized in that, described data transmission system is applied to the ofdm system of following at least a bandwidth: 1.25M, 2.5M, 5M, 10M, 20M.

13. data transmission system according to claim 12 is characterized in that, the quantity of described protection subcarrier and the bandwidth of described ofdm system are proportional.

14. data transmission system according to claim 12 is characterized in that:

Bandwidth at described ofdm system is under the situation of 1.25M, and the quantity of described protection subcarrier is 8;

Bandwidth at described ofdm system is under the situation of 2.5M, and the quantity of described protection subcarrier is 16;

Bandwidth at described ofdm system is under the situation of 5M, and the quantity of described protection subcarrier is 32;

Bandwidth at described ofdm system is under the situation of 10M, and the quantity of described protection subcarrier is 64; And

Bandwidth at described ofdm system is under the situation of 20M, and the quantity of described protection subcarrier is 128.

15. data transmission system according to claim 12 is characterized in that:

Bandwidth at described ofdm system is under the situation of 1.25M, and the shared sub-carrier number of the least unit of resource allocation is 8;

Bandwidth at described ofdm system is under the situation of 2.5M, and the shared sub-carrier number of the least unit of resource allocation is 8;

Bandwidth at described ofdm system is under the situation of 5M, and the shared sub-carrier number of the least unit of resource allocation is 16;

Bandwidth at described ofdm system is under the situation of 10M, and the shared sub-carrier number of the least unit of resource allocation is 16; And

Bandwidth at described ofdm system is under the situation of 20M, and the shared sub-carrier number of the least unit of resource allocation is 16.

16. data transmission system according to claim 9 is characterized in that comprising:

The side-play amount K of the subcarrier of IFFT operation _OFFSETBeing taken as 0 is K _OFFSET=0; Data sending device is used for the subcarrier of each OFDM symbol is designated 0 to N _FFT-1, wherein, wherein, at N _FFTIn the individual subcarrier N is arranged _GUARDIndividual subcarrier is the protection subcarrier, with subcarrier 0 to N _{GUARD, LEFT}-1, N _FFT/ 2 subcarriers and subcarrier N _{GUARD, RIGHT}To subcarrier N _FFT-1 as protection subcarrier, N _{GUARD, LEFT}=N _GUARD/ 2-1, N _{GUARD, RIGHT}=N _FFT-N _GUARD/ 2, with all do not belong to protect subcarrier subcarrier as useful subcarrier, described data sending device is sent to data sink with data on described useful subcarrier; And

Described data sink is used for receiving the data of transmitting by described useful subcarrier according to the distribution of described subcarrier.

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