CN102594763A - Method and system for transmitting data based on Orthogonal Frequency Division Multiplexing (OFDM) - Google Patents

Abstract

The invention discloses a method for transmitting data based on Orthogonal Frequency Division Multiplexing (OFDM), which is applied to transmission of uplink data of middle-distance and short-distance wireless communication systems and is characterized in that: available frequency band of the system is equally divided into N basic sub-frequency bands in advance, wherein the method comprises the following steps: a transmitting site transmits data to a receiving site by a single sub-frequency band or M combined sub-frequency bands, wherein M is equal to 2*n; the transmitting site employs a sampling rate of fs or M*fs of a baseband sample; the receiving site receives data sent from one or a plurality of transmitting sites in the available frequency band; and the receiving site employs a sampling rate of N*fs of the baseband sample. The invention further provides a system for transmitting data based on the OFDM. The method and the system are based on the OFDM technology and combined use of the sub-frequency bands; according to the method and the system, the transmitting site and the receiving site in the wireless communication system are permitted to have different bandwidth configurations, the transmitting site can utilize lower configuration while the receiving site can utilize higher configuration, thereby improving the efficiency, the spectrum efficiency, the throughput rate, etc.; in addition, a plurality of user sites communicating with an access point simultaneously can be realized.

Description

A kind of data transmission method and system based on OFDM

It is on March 25th, 2011 that the application requires the applying date, and application number is 201110074380.X, and denomination of invention is a kind of based on the data transmission method of OFDM and the priority in first to file of system, should all embody in this application at the full content of first to file.

Technical field

The present invention relates to wireless communication technology field, specifically, relate to a kind of data transmission method and system based on OFDM.

Background technology

In WLAN WLAN technology based on 802.11 series standards; Insert (CSMA through carrier sense multiple; Carrier Sense Multiple Access) realizes multi-user's transmission; Be that a plurality of site STA can not insert access point AP simultaneously, can only timesharing insert, even AP is free ideler frequency spectrum resource STA to utilize.Such as, in the system of 802.11n, AP can occupy the 40MHz bandwidth resources; And can be divided into 2 20MHz subbands; STA can only utilize whole 40MHz bandwidth or one of them 20MHz subband to communicate by letter with AP, communicates by letter with AP simultaneously but the STA of two support 20MHz bandwidth can not take one of them 20MHz subband respectively, can only communicate by letter with AP in the main channel in the different time Duan Shangyong 40MHz bandwidth; And 20MHz is from channel idle, and this has just caused the waste of frequency spectrum resource.

OFDM (OFDMA; Orthogonal Frequency Division Multiple Access) be a kind of access mode that adopts in the GSM; A plurality of portable terminals (MS) take that different subcarriers group and base station (BS) communicate simultaneously in the available bandwidth, can improve the availability of frequency spectrum.

Among the existing WLAN; Must the both adopt identical band width configuration when STA communicates by letter with AP,, adopt the bandwidth of 40MHz or the bandwidth of employing 20MHz when STA communicates by letter with AP such as in the system of 802.11n; If AP supports the 40MHz bandwidth in the wlan network; The STA that two 20MHz are arranged, that AP can only adopt the band width configuration of 20MHz to communicate by letter with the STA that competes the main channel resource, therefore cause the waste of 20MHz frequency spectrum resource.In the wireless local area network technology in future, AP can with bandwidth possibly reach 80MHz even more, if continue to continue to use above-mentioned band width configuration scheme, then will cause the more waste of multiple spectra resource.

In the OFDMA mechanism; Though a plurality of terminals can take different subcarriers while and base station communication; But receiving terminal and transmitting terminal need be supported same band width configuration; The FFT that is transmitting terminal inverse fast fourier transform (IFFT, Inverse Fast Fourier Transform) module and receiving terminal fast Fourier transform (FFT, Fast Fourier Transform) module counts necessary identical.The access mode of uplink orthogonal frequency division multiple access access OFDMA is to have relatively high expectations synchronously in addition.In time-domain, the signal demand of a plurality of portable terminals (MS) emission arrives base station (BS) simultaneously and just can not cause intersymbol interference and inter-user interference; In frequency domain; Because a plurality of MS carrier of transmitter crystal oscillator frequency precision are different; Also different with the deviation of BS carrier wave crystal oscillator frequency, the frequency shift (FS) of signal of each MS that therefore arrives BS is also different, and OFDM modulation itself is to the frequency deviation sensitivity; Frequency deviation ability right demodulation must be proofreaied and correct, otherwise multi-user interference can be caused from each MS signal.Therefore, in the OFDMA system, time synchronized and Frequency Synchronization are key issues, need complicated synchronized algorithm.In wireless local area network (WLAN) system, if adopt the access mode of OFDMA will increase equipment cost in order to improve spectrum efficiency.

Summary of the invention

The present invention provides a kind of data transmission method and system based on orthogonal frequency division multiplex OFDM, can realize that a plurality of emission websites communicate with receiving station simultaneously, and complexity is low, can improve the availability of frequency spectrum, system throughput.

A kind of data transmission method based on OFDM provided by the invention is used for short-distance and medium-distance wireless communication system transmitting uplink data, and the available band with system is divided into N basic sub-band in advance, and this method comprises:

The emission website adopts single sub-band or the combination of M sub-frequency bands to send data, wherein M=2 to receiving station ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer;

The emission website adopts baseband sample sampling rate fs or M*fs;

Receiving station receives the data of sending from one or more emission websites in said available band; It is N*fs that receiving station adopts the baseband sample sampling rate.

A kind of data transmission system based on orthogonal frequency division multiplex OFDM provided by the invention is used for the short-distance and medium-distance radio communication, and the available band of this system is divided into N basic sub-band, and this system comprises:

At least two emission websites adopt the combination of single sub-band and/or M sub-band to send data, wherein M=2 to receiving station respectively ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer; Each is launched website and adopts baseband sample sampling rate fs or M*fs;

Receiving station receives the data of respectively launching the website transmission from said in said available band; The baseband sample sampling rate that adopts is N*fs.

Ground preferably, said emission website comprises: the subcarrier generation unit is used at the two ends of said each sub-band the virtual subnet carrier wave being set, at said sub-band edge the protection frequency band to be set.

In sum; Technical scheme provided by the invention; Use based on OFDM technology and sub-band combination, allow the emission site STA in the wireless communication system with receiving station AP different band width configuration to be arranged, the emission site STA can adopt lower configuration to reduce hardware implementation cost; Receiving station AP then can adopt higher configuration to raise the efficiency: the availability of frequency spectrum, throughput etc., and can realize that a plurality of STA communicate with AP simultaneously.In addition; Having increased the protection frequency band at the edge of sub-band is virtual carrier, can avoid disturbing between sub-band, and each sub-frequency bands can do molding filtration without help; And receiving terminal only need be done the matched filtering on the whole frequency band, need not a plurality of band receiver of base and does matched filtering to different sub-bands; Expand Cyclic Prefix (CP), reduced the requirement of time synchronized.Receiving terminal baseband sample sampling rate is N a times of basic subband samples sampling rate; Guarantee an IFFT/FFT module that needs N1 to order on the basic sub-band; The IFFT/FFT module that receiving terminal is ordered with N2=N*N1, and do not need a plurality of parallel N1 point IFFT/FFT modules to come the information of each sub-frequency bands of demodulation.So both can improve the availability of frequency spectrum, system throughput, and can realize that a plurality of STA communicate with AP simultaneously, and needn't increase the cost of system and user site equipment.

Description of drawings

Fig. 1 is a wireless communication system architecture sketch map in the prior art;

Fig. 2 is multi-band OFDM transmitting terminal and a receiving terminal baseband portion module frame chart in the embodiment of the invention;

Fig. 3 (a) and (b), (c) and (d) be respectively several kinds of sub-band division sketch mapes in the embodiment of the invention;

Fig. 4 (a) and 4 (b) are two kinds of sub-band division sketch mapes in addition among Fig. 3 (b).

Embodiment

In view of deficiency of the prior art; The present invention proposes a kind of multi-user data transmission plan that is used for the short-distance and medium-distance radio communication, adopts the multi-user's access way that is similar to OFDM OFDMA, based on OFDM and corresponding synchronous mechanism; The available band of system is divided into N basic sub-band; The bandwidth of transmitting terminal (STA) transceiver can be the frequency band of basic sub-band or sub-band combination, and receiving station (AP) transceiver bandwidth can be N basic sub-band as the case may be, supposes; Basic sub-band is 20MHz; Receiving station (AP) transceiver bandwidth can be 20MHz, 40MHz, 80MHz, promptly also can receive and dispatch the signal of the AP of 80MHz bandwidth for the STA receiver of only supporting the 20MHz bandwidth, like this; The present invention is based on the OFDM modulation technique and can realize that a plurality of STA utilize different sub-band resources to communicate by letter with AP, and reduced required Time and Frequency Synchronization requirement and the synchronization accuracy of OFDMA system.

A kind of data transmission method based on OFDM provided by the invention is used for short-distance and medium-distance wireless communication system transmitting uplink data, and the available band of system is divided into N basic sub-band, and this method comprises:

The emission website adopts single sub-band or the combination of M sub-frequency bands to send data, wherein M=2 to receiving station ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer;

The emission website adopts baseband sample sampling rate fs or M*fs;

FFT handles if baseband portion adopts inverse fast fourier transform IFFT/ fast Fourier transform, and the baseband sample sampling rate refers to the specimen sample speed of inverse fast fourier transform IFFT/ fast Fourier transform FFT module input mouth here;

Receiving station receives the data of sending from one or more emission websites in said whole frequency band; It is N*fs that receiving station adopts the baseband sample sampling rate.

In the data transmission method provided by the invention, baseband portion adopts inverse fast fourier transform IFFT/ fast Fourier transform FFT to handle, and then receiving station adopts and the different FFT length of emission website:

If basic sub-band is with K point IFFT/FFT module, if the emission website takies M basic sub-band, the IFFT/FFT block length of emission website is the M*K point, and the IFFT/FFT block length of receiving station is the N*K point.

If the emission website is supported identical bandwidth with receiving station, IFFT/FFT sub-carrier number, the sampling rate of then launching website and receiving station are all identical;

If a plurality of emission websites are arranged in the system, the bandwidth that each emission website is supported is different, and under the prerequisite that satisfies the band width configuration requirement, a plurality of emission websites can send data with band width configuration separately to receiving station in the bandwidth range of receiving station support.

Described data transmission method also comprises: at the sub-band edge protection frequency band is set, is specially:

At the two ends of said each sub-band the virtual subnet carrier wave is set.

In the data transmission method that the embodiment of the invention provides, send data, then for each emission website is provided with carrier frequency offset respectively, with the centre carrier frequency of confirming respectively to launch website as a plurality of emission websites.

In the data transmission method that the embodiment of the invention provides, send data, the cyclic prefix CP length T of this wireless communication system is set as a plurality of emission websites _CPSatisfy following condition:

T _CP≥2δ+τ _m

Wherein 2 δ are that signal arrives the Round Trip Time Measurement that maximum covering radius experienced that allows, τ from the emission website _mThe multidiameter expansion.

In the embodiment of the invention, the sub-band broadband is 20MHz; And/or M=1,2,4; And/or K=256; And/or baseband sample sampling rate fs=20MHz.

For making principle of the present invention, characteristic and advantage clearer, describe the present invention below in conjunction with specific embodiment.

Fig. 1 is the schematic block diagram of transmitting terminal and receiving terminal, and the embodiment of the invention only relates to the part of module of base band in transmitting terminal and the receiving terminal, and therefore, the module that the present invention does not relate in information source shown in Figure 1, radio frequency, the stay of two nights and the baseband portion repeats no more at this.

At first, the whole frequency band with system is divided into N basic sub-band, each STA website use in the confession system.

In the present embodiment; The whole frequency band bandwidth of system is W=80MHz; It is divided into N=4 basic sub-band; Each basic sub-band bandwidth B=20MHz suppose that each basic sub-band can only be taken separately by an emission site STA, and a STA can use one or more basic sub-bands to transmit data to AP.STA supports 20MHz, 40MHz and 80MHz bandwidth, and AP supports 20MHz, 40MHz and 80MHz bandwidth, when AP has 80MHz bandwidth receiving ability, can receive the data of norator combinations of bands transmission simultaneously.Shown in Figure 2 is that the site STA 1～STA4 of 4 20MHz bandwidth takies the baseband portion module frame chart of different sub-bands when the AP of 80MHz bandwidth transmission data respectively.

Have 4 STA to send data to AP shown in Fig. 2, represent with STA1～STA4, it is the 20MHz bandwidth that each STA takies a basic sub-band, and X1～X4 representes the data from corresponding STA.Only show when realizing being with the OFDM transmission among Fig. 2 and the closely-related module of IFFT/FFT more; Other does not relate to does not influence a module in the complete transceiver yet, repeats no more at this such as coding, constellation point mapping, stream parsing, channel estimating, MIMO detection, decoding etc.

Sub-band division in the embodiment of the invention is shown in Fig. 3 (a).

Fig. 3 is the equivalent base band sketch map of sub-band division, for simplicity, can continue to use the negative frequency notion that the 802.11n standard is used; To positive frequency, but both in itself and indifference with the frequency spectrum shift of negative frequency.AP uses [40MHz, 40MHz] frequency range 80MHz bandwidth altogether, centre frequency f0=0.Only illustrated the situation of STA single antenna among Fig. 3, be applicable to that equally also STA and AP are that many antennas are monopolized sub-band and a plurality of STA situation through space division multiplexing shared Sub frequency band.

Fig. 3 (a) is depicted as the sketch map of 4 shared frequency bands of STA among Fig. 2, wherein, f0=0, STA1 uses [40MHz;-20MHz] frequency range, centre frequency f1=-30MHz, STA2 uses [20MHz, OMHz] frequency range; Centre frequency f2=-10MHz, STA3 uses [0MHz, 20MHz] frequency range, centre frequency f3=10MHz; STA4 uses [20MHz, 40MHz] frequency range, centre frequency f4=30MHz.

The signal model of the sub-band division shown in Fig. 3 (a) is described below.Walk abreast and send 4 road 20MHz signals, can separate the assurance quadrature to each road signal, promptly be modulated to respectively on nonoverlapping frequency range at frequency domain.Sub-carrier number Nfft (counting of IFFT/FFT conversion), sampling interval T _SAnd sample frequency f _SBetween corresponding relation as shown in the formula:

$\mathrm{Ts}=\frac{\mathrm{Tu}}{\mathrm{Nfft}}=\frac{1}{\mathrm{\ΔF}}\·\frac{1}{\mathrm{Nfft}}$

Tu representes the duration of 0FDM symbol.Baseband signal centre frequency f _c=0, when its subcarrier spacing is Δ F=78.125kHz, the sub-carrier number Nfft that adopts in the present embodiment (counting of IFFT/FFT conversion), sampling interval T _SAnd sample frequency f _SBetween corresponding relation as shown in table 1.

Table 1

Bandwidth B	Sub-carrier number Nfft	Sampling interval T S	Sample frequency fs
				20MHz
	256	50ns	20MHz
				40MHz	512	25ns	40MHz
80MHz
		1024	12.5ns	80MHz

Sample frequency fs in the table 1 is minimum sampling rate, can adjust employing greater than the value shown in the table 1.

In the present embodiment, the centre frequency of 4 road signals is respectively f ₁=-30MHz, f ₂=-10MHz, f ₃=10MHz, f ₁=30MHz just in time occupies one section continuous 80MHz channel, and the sub-carrier offset value that each road signal center frequency is corresponding is respectively :-384 Δ F ,-128 Δ F, 128 Δ F, 384 Δ F.

With reference to Fig. 2 and Fig. 3 (a), in the present embodiment, the data of each STA are at first passed through the IFFT conversion of Nfft1=256 point (sub-carrier number); The sampling interval of baseband sample (sampling interval of IFFT module input sample point) is 50ns, passes through D/A (D/A partly comprises LPF) then, carries out frequency spectrum shift again; Centre frequency is respectively f1～f4, f1=f0-30 wherein, f2=f0-10; F3=f0+10, f4=f0+30, unit is MHz; Through being received by AP behind other resume module of base band, radio-frequency channel and the channel, the data that AP receives are at first also through the processing of radio-frequency channel and other module of base band, and the baseband sample point sampling of AP is 12.5ns at interval; The FFT conversion of ordering through Nfft2=1024 can be carried out subsequent treatment from the data that corresponding frequency band is taken out different STA.

Do not consider under the situation of time deviation, frequency departure, interference noise, suppose that the receiving terminal base band receives that the continuous signal of different carrier frequency is following:

$r\left(t\right)=\frac{1}{N}\{\underset{k=-128}{\overset{127}{\mathrm{\Σ}}}{X}_k\exp \left(j2\mathrm{\π}(k-384)\mathrm{\ΔFt}\right)+\underset{n=-128}{\overset{127}{\mathrm{\Σ}}}{Y}_n\exp \left(j2\mathrm{\π}(n-128)\mathrm{\ΔFt}\right)$ (1)

$+\underset{k=-128}{\overset{127}{\mathrm{\Σ}}}{X}_k\exp \left(j2\mathrm{\π}(k+128)\mathrm{\ΔFt}\right)+\underset{n=-128}{\overset{127}{\mathrm{\Σ}}}{Y}_n\exp \left(j2\mathrm{\π}(n+384)\mathrm{\ΔFt}\right)$

To signal sampling, get t=nT _s

$r\left(n\right){|}_{t=n{T}_s}=\frac{1}{N}\{\underset{k=-128}{\overset{127}{\mathrm{\Σ}}}{W}_k\exp \left(j2\mathrm{\π}(k-384)\mathrm{\ΔFn}{T}_s\right)+\underset{n=-128}{\overset{127}{\mathrm{\Σ}}}{X}_n\exp \left(j2\mathrm{\π}(n-128)\mathrm{\ΔFn}{T}_s\right)$

$+\underset{k=-128}{\overset{127}{\mathrm{\Σ}}}{Y}_k\exp \left(j2\mathrm{\π}(k+128)\mathrm{\ΔFn}{T}_s\right)+\underset{n=-128}{\overset{127}{\mathrm{\Σ}}}{Z}_n\exp \left(j2\mathrm{\π}(n+384)\mathrm{\ΔFn}{T}_s\right)---\left(2\right)$

$=\frac{1}{N}\{\underset{k^{\′}=-512}{\overset{-257}{\mathrm{\Σ}}}{W}_{k^{\′}+384}\exp \left(j2\mathrm{\π}{k}^{\′}\mathrm{\ΔFn}{T}_s\right)+\underset{n^{\′}=-256}{\overset{-1}{\mathrm{\Σ}}}{X}_{n^{\′}+128}\exp \left(j2\mathrm{\π}{n}^{\′}\mathrm{\ΔFn}{T}_s\right)$

$+\underset{l^{\′}=0}{\overset{255}{\mathrm{\Σ}}}{Y}_{l^{\′}-128}\exp \left(j2\mathrm{\π}{l}^{\′}\mathrm{\ΔFn}{T}_s\right)+\underset{m^{\′}=256}{\overset{511}{\mathrm{\Σ}}}{Z}_{m^{\′}-384}\exp \left(j2\mathrm{\π}{m}^{\′}\mathrm{\ΔFn}{T}_s\right)\}$

Receiver to the 80MHz bandwidth; N=1024,

substitution following formula gets:

$r\left(n\right){|}_{t=n{T}_s}=\frac{1}{N}\left\{\underset{k=-N/2}{\overset{N/2-1}{\mathrm{\Σ}}}{Q}_k\exp \left(j2\mathrm{\πk}\frac{n}{N}\right)\right\}---\left(3\right)$

R (n) is done 1024 FFT conversion can demodulation obtain signal W, X, Y, Z.

For guaranteeing that the signal period is consistent, to the signal of different bandwidth, the sampling rate of FFT module input data is different.Under the 20MHz bandwidth, 256 FFT, the sampling period should be 50ns; And under the 80MHz bandwidth, 1024 FFT, the sampling period is 12.5ns.

In the embodiment of the invention, group of subbands supplies each website to use altogether, such as, can two sub-frequency bands synthesize a use, or the synthetic frequency band of all group of subbands uses.Sub-band combination mode in the present embodiment is shown in Fig. 3 (b), Fig. 3 (c) and Fig. 3 (d).

Fig. 3 (b) is depicted as the sub-band division signal of the shared 80MHz frequency spectrum of STA of STA and a 40MHz bandwidth of two 20MHz bandwidth, and the centre frequency of three sub-frequency bands is respectively f1=-30MHz, f2=0, f3=30MHz.In addition, Fig. 3 (b) also has two kinds of distortion, and is as shown in Figure 4.

Fig. 3 (c) is depicted as the sub-band division signal of the shared 80MHz frequency spectrum of STA of two 40MHz bandwidth, and the centre frequency of two sub-frequency bands is respectively f1=-20MHz, f2=20.

The STA that Fig. 3 (d) is depicted as a 80MHz bandwidth takies the sub-band division signal of all 80MHz frequency spectrums, and the sub-band centre frequency is f1=0.

Wherein, Fig. 3 (b) is depicted as the situation of the shared 80MHz frequency spectrum of STA of STA and a 40MHz bandwidth of two 20MHz bandwidth, and frequency band distributes also convertible, specifically as shown in Figure 4.

When AP is configured to 40MHz or 80MHz bandwidth, allow in its frequency spectrum, to have idle basic sub-band or basic sub-band combination.

If the emission website is supported identical bandwidth with receiving station, IFFT/FFT sub-carrier number, the sampling rate of then launching site STA and receiving station are all identical;

If a plurality of emission websites are arranged in the system, the bandwidth that each emission website is supported is different, and under the prerequisite that satisfies the band width configuration requirement, a plurality of emission websites can send data with band width configuration separately to receiving station in the bandwidth range of receiving station support.

For example, if the system bandwidth available bandwidth is 40MHz, then AP supports 40MHz, and STA supports 20MHz or 40MHz, and AP supports that two STA transmit simultaneously.If system's available bandwidth is 20MHz, also can this frequency band be continued to divide, a part of resource in each STA service band, but the centre frequency of each STA is all identical with AP, the no longer extra frequency spectrum shift (centre frequency biasing) of doing.

The shared sub-band of each STA all has virtual subnet carrier wave separately, is arranged on the edge (two ends) of sub-band, is used for as the protection frequency band.Each STA only need do the molding filtration on its bandwidth of supporting separately, rather than the molding filtration on the whole W.And AP does the molding filtration on the whole bandwidth W, so AP can support the STA of different bandwidth configuration neatly.

In order to eliminate or to reduce to produce intersymbol interference (ISI to greatest extent; Inter-Symbol Interference) and multi-user interference, need synchronization mechanism reasonable in design in the system, specifically; Introduce Cyclic Prefix (CP; Cyclic Prefix), and the length of cyclic prefix CP changes along with transmission mode, frame structure and corresponding protocol, needs to design the length of cyclic prefix CP in the system that meets the demands.In the embodiment of the invention, the emission site STA can be confirmed a time point t according to the synchronization preamble of downlink frame when receiving the downlink frame that receiving station AP sends ₀, each STA is that benchmark calculates uplink constantly with the time point of estimating separately, the CP length in the design system guarantees to have covered Round Trip Time Measurement 2 δs and the multidiameter extended by tau of the STA of furthest to AP _m, consider time synchronization error again, then the multipath signal of all STA all can arrive STA in the CP scope, is unlikely to produce intersymbol interference (ISI) and multi-user interference.

In the embodiment of the invention, send data, the cyclic prefix CP length T of this wireless communication system is set as a plurality of emission websites _CPNeed satisfy following condition:

T _CP≥2δ+τ _m。

The embodiment of the invention also provides a kind of data transmission system based on OFDM, is used for the short-distance and medium-distance radio communication, and the available band of this system is divided into N basic sub-band, and this system comprises:

At least two emission websites adopt the combination of single sub-band and/or M sub-band to send data, wherein M=2 to receiving station respectively ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer; Each is launched website and adopts baseband sample sampling rate fs or M*fs;

Receiving station receives the data of respectively launching the website transmission from said in said system whole frequency band; The baseband sample sampling rate that adopts is N*fs.

Ground preferably, wherein said emission website comprises:

The subcarrier generation unit is used at the two ends of said each sub-band the virtual subnet carrier wave being set, at said sub-band edge the protection frequency band to be set.

In the embodiment of the invention, said sub-band broadband is 20MHz; And/or M=1,2,4; And/or K=256; And/or baseband sample sampling rate fs=20MHz.

If the emission website is supported identical bandwidth with receiving station, IFFT/FFT sub-carrier number, the sampling rate of then launching site STA and receiving station are all identical;

If a plurality of emission websites are arranged in the system, the bandwidth that each emission website is supported is different, and under the prerequisite that satisfies the band width configuration requirement, a plurality of emission websites can send data with band width configuration separately to receiving station in the bandwidth range of receiving station support.

In sum; Technical scheme provided by the invention; Use based on OFDM technology and sub-band combination, allow the emission site STA in the wireless communication system with receiving station AP different band width configuration to be arranged, the emission site STA can adopt lower configuration to reduce hardware implementation cost; Receiving station AP then can adopt higher configuration to raise the efficiency: the availability of frequency spectrum, throughput etc., and can realize that a plurality of STA communicate with AP simultaneously.In addition; Having increased the protection frequency band at the edge of sub-band is virtual carrier, can avoid disturbing between sub-band, and each sub-frequency bands can do molding filtration without help; And receiving terminal only need be done the matched filtering on the whole frequency band; Need not a plurality of band receiver of base and do matched filtering, expanded Cyclic Prefix (CP), reduce the requirement of time synchronized to different sub-bands.Receiving terminal baseband sample sampling rate is N a times of basic subband samples sampling rate; Guarantee an IFFT/FFT module that needs N1 to order on the basic sub-band; The IFFT/FFT module that receiving terminal is ordered with N2=N*N1, and do not need a plurality of parallel N1 point IFFT/FFT modules to come the information of each sub-frequency bands of demodulation.So both can improve availability of frequency spectrum system throughput, and can realize that a plurality of STA communicate with AP simultaneously, and needn't increase the cost of system and user site equipment.

Though the present invention with preferred embodiment openly as above; But it is not to be used for limiting the present invention; Any those skilled in the art are not in breaking away from essence of the present invention and scope; Can make possible change and modification, so protection scope of the present invention should be as the criterion with the scope that claim of the present invention was defined.

Claims (11)

1. the data transmission method based on OFDM is used for short-distance and medium-distance wireless communication system transmitting uplink data, it is characterized in that, the available band of system is divided into N basic sub-band, and this method comprises:

The emission website adopts single sub-band or the combination of M sub-frequency bands to send data, wherein M=2 to receiving station ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer;

The emission website adopts baseband sample sampling rate fs or M*fs;

Receiving station receives the data of sending from one or more emission websites in said available band; It is N*fs that receiving station adopts the baseband sample sampling rate.

2. data transmission method as claimed in claim 1 is characterized in that, baseband portion adopts inverse fast fourier transform IFFT/ fast Fourier transform FFT to handle, and then receiving station adopts and the different FFT length of emission website:

If basic subband is with K point IFFT/FFT module, if the emission website takies M basic subband, the IFFT/FFT block length of emission website is the M*K point, and the IFFT/FFT block length of receiving station is the N*K point.

3. data transmission method as claimed in claim 2 is characterized in that,

If the emission website is supported identical bandwidth with receiving station, IFFT/FFT sub-carrier number, the sampling rate of then launching website and receiving station are all identical;

If a plurality of emission websites are arranged in the system, the bandwidth that each emission website is supported is different, and under the prerequisite that satisfies the band width configuration requirement, a plurality of emission websites can send data with band width configuration separately to receiving station in the bandwidth range of receiving station support.

4. data transmission method as claimed in claim 1 is characterized in that, also comprises: at the sub-band edge protection frequency band is set, is specially:

At the two ends of said each sub-band the virtual subnet carrier wave is set.

5. data transmission method as claimed in claim 1 is characterized in that, sends data as a plurality of emission websites, then for each emission website is provided with carrier frequency offset respectively, with the centre carrier frequency of confirming respectively to launch website.

6. data transmission method as claimed in claim 1 is characterized in that, sends data as a plurality of emission websites, and the cyclic prefix CP length T of this wireless communication system is set _CPSatisfy following condition:

T _CP≥2δ+τ _m

Wherein 2 δ are that signal arrives the Round Trip Time Measurement that maximum covering radius experienced that allows, τ from the emission website _mBe the multidiameter expansion.

7. data transmission method as claimed in claim 1 is characterized in that, said sub-band broadband is 20MHz; And/or M=1,2,4; And/or K=256; And/or baseband sample sampling rate fs=20MHz.

8. the data transmission system based on OFDM is used for the short-distance and medium-distance radio communication, it is characterized in that, the available band of this system is divided into N basic sub-band, and this system comprises:

At least two emission websites adopt the combination of single sub-band and/or M sub-band to send data, wherein M=2 to receiving station respectively ⁿ, n=0,1,2 ..., and M≤N, N, M are positive integer; Each is launched website and adopts baseband sample sampling rate fs or M*fs;

Receiving station receives the data of respectively launching the website transmission from said in said available band; The baseband sample sampling rate that adopts is N*fs.

9. data transmission system as claimed in claim 8 is characterized in that, said emission website comprises:

The subcarrier generation unit is used at the two ends of said each sub-band the virtual subnet carrier wave being set, at said sub-band edge the protection frequency band to be set.

10. like claim 8 or 9 described data transmission systems, it is characterized in that,

Said sub-band broadband is 20MHz; And/or M=1,2,4; And/or K=256; And/or baseband sample sampling rate fs=20MHz.

11. data transmission system as claimed in claim 8 is characterized in that,

If the emission website is supported identical bandwidth with receiving station, IFFT/FFT sub-carrier number, the sampling rate of then launching site STA and receiving station are all identical;

If a plurality of emission websites are arranged in the system, the bandwidth that each emission website is supported is different, and under the prerequisite that satisfies the band width configuration requirement, a plurality of emission websites can send data with band width configuration separately to receiving station in the bandwidth range of receiving station support.

Images