CN103023850A - Variable-bandwidth OFDM (Orthogonal Frequency Division Multiplexing) transmitter and receiver - Google Patents
Variable-bandwidth OFDM (Orthogonal Frequency Division Multiplexing) transmitter and receiver Download PDFInfo
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Abstract
The invention belongs to the field of wireless communication, and relates to a variable-bandwidth OFDM (Orthogonal Frequency Division Multiplexing) transmitter and receiver which are used for transmitting and receiving the OFDM signals composed of effective information symbols and cyclic prefixes. The transmitter 100 comprises a segment manager 101, a symbol adding unit 102, a mapping unit 103, an OFDM signal generation unit 104, a frame length regulation unit 105, a carrier regulation unit 106 and a carrier amount storage unit 107; the receiver 202 comprises a cyclic prefix detection unit 201, an FFT (Fast Fourier Transform) unit 202, a data screening unit 203, a data post-processing unit 204, a carrier estimation unit 205, a channel idle bandwidth estimation unit 206, a carrier information storage unit 207 and a carrier change decision-making unit 208. The transmitter can be used for dynamically regulating the amount of carriers according to the communication bandwidth change feed-back information provided by the receiver, so as to control the communication bandwidth and dynamically change the information bit transmission rate.
Description
Technical field
The invention belongs to radio communication field, be specifically related to a kind of OFDM transmitter and receiver of bandwidth varying, be used for the frame ofdm signal that sending and receiving is made of effective information symbol and Cyclic Prefix.
Background technology
The OFDM technology is a kind of transmission plan that utilizes a plurality of orthogonal carrier frequencies transmitted signals.Intrasystem high-speed data-flow is by string and conversion, so that the data symbol persistence length on each subcarrier increases relatively, thereby effectively reduce the intersymbol interference (ISI) that the wireless channel temporal dispersion brings, and the complexity of equalizer in the receiver is reduced.The equal pairwise orthogonal of all subcarriers in the OFDM transmitted signal bandwidth, thereby frequency spectrum can be overlapped, can maximally utilise frequency spectrum resource, when sub-carrier number was very large, the availability of frequency spectrum can be near the Nyquist maximum.From frequency domain, because of multipath frequency of occurrences selectivity decline or when existing the arrowband to disturb, only have a fraction of subcarrier to be affected in the channel, therefore, ofdm system can resist to a certain extent multipath and the arrowband disturbs, and greatly reduces the error rate.
Present OFDM transmitter and OFDM receiver mainly are divided into two large classes.
The first kind is that number of carriers is fixed, i.e. the fixing OFDM transmitting/receiving system of communication bandwidth.The problem that this system exists mainly contains: when the interference of relatively high power appearred in side channel, system be because can not changing in real time the communication bandwidth of (reducing) this channel, thereby made the edge subcarrier of this channel be subject to larger interference, the reliability that impact is transmitted; And when side channel is idle, because communication bandwidth fixes, can not effectively utilizes the idle frequency band resource and cause the waste of band resource.
Equations of The Second Kind is the OFDM transmitting/receiving system of adaptive-bandwidth.Although the bandwidth of this system is variable, because its bandwidth only changes with the variation of source data transmission rate, therefore still can not effectively eliminate adjacent-channel interference to the impact of this channel edge subcarrier, can not improve bandwidth availability ratio.In addition, the variation of bandwidth will be through the repeatedly affirmation of transmitter and receiver, and process is very complicated, and also there is disturbed risk in the transmission of confirmation itself.
Summary of the invention
For the problems referred to above, the objective of the invention is by this channel width and near frequency resource thereof being taken the accurate estimation of situation, control in real time the variation of this channel width, control dynamically, intelligently number of subcarriers, thereby farthest improve reliability and the availability of frequency spectrum of OFDM transmitter and OFDM receiver.
For achieving the above object, the present invention takes following technical scheme:
A kind of OFDM transmitter and receiver of bandwidth varying, be used for the frame ofdm signal that sending and receiving is made of effective information symbol and Cyclic Prefix, it is characterized in that, described transmitter can dynamically be adjusted the carrier wave number according to the communication bandwidth change feedback information that described receiver provides, thereby the control communication bandwidth dynamically changes transfer rate of information simultaneously.
Described transmitter 100 comprises: segment management device 101, symbol adder 102, map unit 103, ofdm signal generation unit 104, Frame Size Adjustment unit 105, carrier wave adjustment unit 106, carrier number memory cell 107.
Ofdm signal generation unit 104 comprises pilot tone and training symbol maker 104a, data and pilot frequency distribution device 104b, IFFT unit 104c and protection interval adding device 104d.
Pilot tone and training symbol maker 104a, output connects data and pilot frequency distribution device.Before data symbol sends, the generation cycle prefix signal, and when data symbol sends, generate pilot frequency information.
Data and pilot frequency distribution device 104b link to each other with map unit 103 with training symbol maker 104a with IFFT unit, pilot tone respectively.To press certain arrangement mode composition frequency spectrum data bag from the information data of map unit 103 and from the pilot data of pilot tone and training symbol maker 104a, send IFFT unit 104c to.
IFFT unit 104c links to each other with protection interval adding device 104d with pilot frequency distribution device 104b with data.To carry out quick inverse Fourier transform from the frequency spectrum data bag of data and pilot frequency distribution device 104b, and parallel data be converted to export protection interval adding device behind the serial time domain data to.
Protection interval adding device 104d, 104c links to each other with the IFFT unit.Add the protection interval between two discontinuous information symbols of the serial time domain data of sending here to IFFT unit 104c.
Frame Size Adjustment unit 105 comprises figure place computing unit 105a and the interior transmission of frame total information figure place computing unit 105b in the symbol.
Figure place computing unit 105a in the symbol, respectively with frame in transmission total information figure place computing unit 105b, carrier wave adjustment unit 106 link to each other with segment management device 101.The available carrier wave that provides according to carrier number adjustment unit 106 is counted calculated signals and is gone out transmissible information bit number in each symbol.
Transmission total information figure place computing unit 105b links to each other with figure place computing unit 105a in the symbol in the frame.According to the symbol internal information figure place that figure place computing unit 105a in the symbol provides, calculate in the frame of reaction instant messages speed and can transmit the total information figure place, and information rate adjusts the feedback information of information bit transmission rate to host computer accordingly.
Carrier wave adjustment unit 106, carrier wave adjustment unit 106 comprise carrier number determinant 106a and pilot tone adjustment unit 106b.
Carrier number determinant 106a links to each other with carrier number memory cell 107 with the carrier wave Change Strategy unit 208 of pilot tone adjustment unit 106b, described receiver respectively.Reception is read the carrier information in the carrier number memory cell 107 from the bandwidth feedback information of receiver, according to the bandwidth feedback information, carrier information is done suitable adjustment and upgrade carrier information in the carrier number memory cell 107; Above-mentioned method of adjustment is: when communication bandwidth changes delta B, corresponding number of carriers is changed to Δ C=Δ B/S
BW, S wherein
BWFrequency interval for subcarrier.
Pilot tone adjustment unit 106b links to each other with carrier number determinant 106a, ofdm signal generation unit 104 and Frame Size Adjustment unit 106 respectively.According to pilot number and the position of pilot tone in frequency band in the number of carriers adjustment transmission frame structure, pilot number is decided to be 1/16 of total number of subcarriers, and all pilot tones are evenly distributed in the whole communication bandwidth, adjust the result and send to respectively Frame Size Adjustment unit 106 and ofdm signal generation unit 104.Carrier number memory cell 107 links to each other with carrier wave adjustment unit 106, is used for storing the bandwidth information of current communication.
Described receiver 200 comprises: Cyclic Prefix detecting unit 201, FFT unit 202, data screening unit 203, Data Post unit 204, carrier estimation unit 205, channel idle bandwidth estimation unit 206, carrier information memory cell 207, carrier wave Change Strategy unit 208.
Cyclic Prefix detecting unit 201, input connects antenna, and output connects FFT unit 202.For detection of the Cyclic Prefix that is positioned at each OFDM frame.
Data Post unit 204 links to each other with data screening unit 203.Be used for separating the 16QAM mapping and separate forward error correction coding.
Small echo separates and reconfiguration unit 205a, links to each other with described FFT unit 202 with frequency spectrum cross-correlation unit 205b.Adopt the Haar small echo that the frequency spectrum data from FFT unit 202 is carried out separating treatment, obtain changing violent part and relative level and smooth part in the frequency spectrum, adopt wherein level and smooth data division that frequency spectrum is reconstructed, finally obtain approximate rectangular frequency spectrum.
Frequency spectrum cross-correlation unit 205b separates with reconfiguration unit 205a with small echo and to link to each other with carrier information memory cell 207.To the Cyclic Prefix frequency spectrum data after being processed with reconfiguration unit 205a by the small echo separation, carry out the cross-correlation of different starting points, finally obtain one group of bandwidth that bandwidth namely is this communication of correlation maximum.
Channel idle bandwidth estimation unit 206 comprise edge bandwidth power density integrator 206a, noise gate comparing unit 206b and free time computing unit 206.
Edge bandwidth power density integrator 206a links to each other with data screening unit 203 with noise gate comparing unit 206b.To carry out integration, the edge calculation bandwidth power to the edge bandwidth power density beyond this communication bandwidth.
Noise gate comparing unit 206b links to each other with edge bandwidth power density integrator 206a with free time computing unit 206c.With edge bandwidth power P
InWith noise power P
NoisCompare, work as P
In1.5P
NoiseThe time, the output bandwidth Seize ACK message; Work as P
In＜1.5P
NoiseThe time, the output bandwidth idle signal if free time surpasses an OFDM frame length, thinks that then this edge bandwidth is idle.
Free time computing unit 206c links to each other with carrier wave Change Strategy unit 208 with noise gate comparing unit 206b.When receiving the bandwidth idle signal that is fed back by described noise gate comparing unit, record current idle bandwidth information, and beginning cumulative bandwidth free time, if this bandwidth remains idle condition within the whole OFDM information frame time, carrier wave Change Strategy unit 208 will send feedback information to transmitter, improves signal bandwidth.
Carrier information memory cell 207 links to each other with data screening unit 203 with carrier estimation unit 205.Be used for this communication bandwidth information of storage.
Carrier wave Change Strategy unit 208 links to each other with channel idle bandwidth estimation unit 206.Whether be used for the decision-making communication bandwidth changes.
For estimated spectral information correctly, the ofdm signal frame structure of transmission adopts Cyclic Prefix to add the compound mode of information symbol.Cyclic Prefix is comprised of a plurality of identical training symbols, thereby the frequency spectrum data that each training symbol is corresponding is identical in theory.A certain frequency range data in the training symbol frequency spectrum data that difference is obtained are constantly carried out cross-correlation operation and are recorded correlation, when this correlation is maximum, illustrates to participate in the bandwidth that relevant frequency band is this communication.In fact, before carrying out associative operation, in order to make frequency spectrum closer to ideal situation, the carrier estimation unit at first carries out wavelet transformation to frequency spectrum data, extract more level and smooth part in the frequency spectrum, make frequency spectrum closer to ideal rectangle, improve the reliability of carrier estimation.
Channel idle bandwidth estimation unit detects the outer bandwidth power of this communication in real time.When an OFDM frame length of free time accumulative total, judge that just the channel existence does not utilize frequency band, prevents from covering with the side channel frequency band.
The present invention can Real-Time Monitoring channel width utilize situation owing to taking above technical scheme, and according to the estimation result of channel width, dynamically adjusts in real time the subcarrier number, when reducing the outer interference of communication band, has also improved channel utilization.
Description of drawings
Fig. 1 is the functional block diagram of bandwidth varying OFDM transmitter of the present invention;
Fig. 2 is the functional block diagram of the Frame Size Adjustment unit of bandwidth varying OFDM transmitter of the present invention;
Fig. 3 is the carrier wave adjustment unit of bandwidth varying OFDM transmitter of the present invention;
Fig. 4 is the ofdm signal generation unit of bandwidth varying OFDM transmitter of the present invention;
Fig. 5 is the functional block diagram of bandwidth varying OFDM receiver of the present invention;
Fig. 6 is the functional block diagram of the Cyclic Prefix detecting unit of bandwidth varying OFDM receiver of the present invention;
Fig. 7 is the functional block diagram of the subcarrier estimation unit of bandwidth varying OFDM receiver of the present invention;
Fig. 8 is the side channel estimation of available bandwidth Elementary Function calcspar of bandwidth varying OFDM receiver of the present invention;
Fig. 9 is the reception of OFDM transmitter and the frame structure of launching of bandwidth varying OFDM receiver of the present invention and bandwidth varying.
Among the figure; 100.OFDM transmitter; 101. segment management device; 102. symbol adder; 103. map unit; 104.OFDM signal generation unit; 104a. data and pilot frequency distribution device; 104b.IFFT unit; 104c. protection interval adding device; 104d. pilot tone and training symbol maker; 105. Frame Size Adjustment unit; 105a. transmission total information figure place computing unit in the figure place computing unit in the symbol, 105b. frame, 106. carrier wave adjustment units; 106a. carrier number determinant; 106b. the pilot tone adjustment unit, 107. carrier number memory cell, 200.OFDM receiver; 201. Cyclic Prefix detecting unit; 201a. delay cell, 201b. complex conjugate unit, 201c. multiplier; 201d. data accumulation unit; 201e. the data accumulation unit, 201f. divider, 201g. buffer; 202.FFT unit; 203. the data screening unit, 204. Data Post unit, 205. carrier estimation unit; 205a. small echo separates and heavy unit; 205b. the frequency spectrum cross-correlation unit, 206. channel idle bandwidth estimation unit, 206a. edge bandwidth power density integral unit; 206b. noise gate identifying unit; 206c. free time computing unit, 207. carrier information memory cell, 208. carrier wave Change Strategy unit.
Embodiment
Fig. 9 shows and relates to OFDM transmitter of the present invention and receiver emission and the OFDM frame structure that receives.This OFDM frame is made of Cyclic Prefix and two parts of data.Wherein: Cyclic Prefix is comprised of a plurality of identical training symbols; Data division is made of protection interval and information symbol.The partial information data at protection interval and information symbol end thereafter are identical.The number of information symbol and training structure is definite constant in each OFDM frame.
As shown in Figure 1, the OFDM transmitter of the bandwidth varying relevant with the first execution mode of the present invention mainly has segment management device 101, symbol adder 102, map unit 103, ofdm signal generation unit 104, Frame Size Adjustment unit 105, carrier wave adjustment unit 106, carrier number memory cell 107.
Frame Size Adjustment unit 105 sends feedback information to the upper level Data Source: when the communication bandwidth reduction, when number of carriers reduces, transmitter sends data rate to be reduced, and feed back to data source this moment, reduces the signal of the data rate that imports transmitter 100 into; When the communication bandwidth raising, when number of carriers increases, transmitter sends data rate and improves, and feed back to data source this moment, improves the signal of the data rate that imports transmitter 100 into.Host computer imports data rate N into:
B=KN
Wherein, K is the rate conversion factor in the coding link, and when communication bandwidth changes delta B, phase code rate variable quantity is Δ B/K.
As shown in Figure 2, Frame Size Adjustment unit 105 is comprised of transmission total information figure place computing unit 105b in figure place computing unit 105a and the frame in the symbol.When communication bandwidth changed, the entrained information bit number of symbol in each OFDM frame also will change thereupon, and namely information symbol length also will change.OFDM frame internal symbol number is fixed, and when frame internal symbol length variations, the transmission total bit also can change in the frame, i.e. also respective change of the rate of information throughput.
The available carrier wave that figure place computing unit 105a provides according to the carrier number adjustment unit in the symbol is counted calculated signals and is gone out transmissible information bit number in each information symbol.
The symbol internal information figure place that transmission total information figure place computing unit 105b provides according to figure place computing unit 105a in the symbol in the frame calculates in the frame can transmit the maximum information figure place.Reacted instant messages speed because can transmit the maximum information figure place in the frame, thus in the frame transmission total information figure place computing unit 105b according to the feedback information that can transmit the maximum information figure place in the frame host computer is adjusted the information bit transmission rate.
102 pairs of packets that sended over by segment management device 101 of symbol adder carry out forward error correction coding and convolutional encoding, and wherein forward error correction coding comprises scrambler module and two parts of interleaving block.
102 pairs of packets that sended over by segment management device 101 of symbol adder carry out forward error correction coding and convolutional encoding.
Error correcting code comprises scrambler coding, three parts of channel code and interleaving coding.Wherein, length of scrambler module employing is 127 frame synchronous scrambler scrambling, and its generator polynomial is shown below:
S(x)=x
7+x
3+1
Wherein, x represents an information bit in the shift register that length is 8bit, and its upper right footmark represents the position of this information bit in whole shift register.
Its essence is feedback shift register, can effectively list entries be confused, and makes correlation reduction between the output numeric code.
Convolution code adopts the convolution coder of 1/2 code check to generate: input one digit number word bit will produce two output data.The generator polynomial of wherein exporting data A, B is respectively:
A(x)=x
6+x
5+x
3+x
2+1
B(x)=x
6+x
3+x
2+x+1
Carrier wave adjustment unit 106 judges according to the bandwidth feedback information that imports into whether number of carriers increases or reduce, and adjusts pilot number and the position of pilot tone in whole communication bandwidth.As shown in Figure 3, carrier wave adjustment unit 106 is counted determinant 106a by available carrier wave and pilot tone adjustment unit 106b consists of.
Carrier number determinant 106a receives the bandwidth feedback information from receiver, reads the carrier information in the carrier number memory cell 107, according to feedback information, carrier information is done suitable adjustment afterwards and upgrade carrier information in the carrier number memory cell 107.Above-mentioned adjustment mode is: when communication bandwidth changes delta B, corresponding number of carriers is changed to Δ C=Δ B/S
BW, S wherein
BWFrequency interval for subcarrier.
Carrier number determinant 106a also will pass to pilot tone adjustment unit 106b with the result who adjusts after finishing the number of carriers adjustment.Pilot tone adjustment unit 106b is according to pilot number and the position of pilot tone in frequency band in the quantity adjustment transmission frame structure of carrier wave.Reach balance in order to make between efficient and the performance, the quantity of pilot tone is decided to be 1/16 of total number of subcarriers, and all pilot tones are evenly distributed in the whole communication bandwidth.Adjust the result and send to respectively Frame Size Adjustment unit 105 and ofdm signal generation unit 104.
The frequency spectrum data that ofdm signal generation unit 104 will consist of from data and the pilot data of map unit 103 carries out quick inverse Fourier transform, will send as transmitted signal behind the transformation results interpolation protection interval.
Ofdm signal generation unit 104 as shown in Figure 4, is comprised of with pilot frequency distribution device 104a, IFFT unit 104b, protection interval adding device 104c and pilot tone and training symbol maker 104d data.Data and pilot frequency distribution device 104a will press certain arrangement mode composition frequency spectrum data bag from the information data of map unit 103 and from the pilot data of pilot tone and training symbol maker 104d, send IFFT unit 104b to and carry out quick inverse Fourier transform.In addition, IFFT unit 104b also has the parallel-to-serial translation function, and the parallel data of exporting after the IFFT conversion will convert the serial time domain data to and export protection interval adding device 104c to.
The function of pilot tone and training symbol maker 104d has two: the first, and before data symbol sends, the generation cycle prefix signal; The second, when data symbol sends, generate pilot frequency information.
Protection interval adding device 104c copies to N data of each Frame afterbody on the head of this frame, makes two discontinuous frames that sent by IFFT unit 104b become continuous time domain data.In the said process, suppose that two spaces between the frame can hold N data.
As shown in Figure 5, the bandwidth varying OFDM receiver 200 relevant with the first execution mode of the present invention mainly is comprised of Cyclic Prefix detecting unit 201, FFT unit 202, data screening unit 203, Data Post unit 204, carrier estimation unit 205, channel idle bandwidth estimation unit 206, carrier information memory cell 207 and carrier wave Change Strategy unit 208.
Cyclic Prefix detecting unit 201 is for detection of the leading Cyclic Prefix of each Frame.Specifically, as shown in Figure 6, this unit is comprised of delay cell 201a, complex conjugate unit 201b, complex multiplication unit 201c, data accumulation unit 201d, data accumulation unit 201e, complex division unit 201f and buffer 201g.
Delay cell 201a length is the data length of a training symbol.
Delay cell 201a, complex conjugate unit 201b, complex multiplication unit 201c, data accumulation unit 201d finish training symbol and the associative operation that postpones training symbol in the Cyclic Prefix in the Cyclic Prefix jointly.Relevant result is called the delay-correlated value, is designated as C, and the expression formula of C is:
R wherein
nBe the reception signal,
Be the conjugate of the reception signal that postponed a training symbol length, D is the data length of an aforementioned training symbol.
Delay cell 201a, data accumulation unit 201e finish the energy calculating operation of the training symbol in the Cyclic Prefix after the delay jointly.Calculate power and be designated as P, the expression formula of P is:
R wherein
nBe the reception signal,
For receiving the conjugate of signal.
When only having noise in the signal that receives, ideally the delay-correlated value C of output is 0, because the cross-correlation coefficient of noise is 0, therefore before Frame arrived, the judgment variables value was very little.When receiving second training symbol, because it is identical to participate in relevant signal, the delay-correlated value begins obvious increase, and the relevant smooth of a lasting M-1 symbol lengths occur, is indicating that new ofdm signal frame arrives.Simultaneously, complex division unit 201f will arrive information to data accumulation unit 201e feedback ofdm signal frame.Notice that this feedback information comprises two states: when detecting training symbol, output state 1; When not detecting training symbol, output state 2.This signal will export data buffer 201g to and be used for controller buffer output with synchronous reception signal.Note, comprise M training symbol in the hypothesis Cyclic Prefix in the said process.
P
AvaWill be as the threshold value that detects information symbol and whether finish.After Cyclic Prefix finished receiving, data accumulation unit 201e continued to calculate realtime power P
t, and with this power and P
AvaCompare.Work as P
tP
Ava, then think the current information symbol that receives at/2 o'clock; Work as P
t＜P
Ava/ 2 also continue an information symbol during cycle, think that information symbol finishes receiving.Whether court verdict will form the data arriving signal and export buffer 201g to, be used to indicate information symbol and arrive.
The buffer 201g course of work can be described as: when the feedback information from complex division unit 201f is state 1, and the data in the output buffer memory, and output synchronizing signal, indicating these output data is Cyclic Prefix; When the signal instruction information symbol from data accumulation unit 201e arrives, the data in the output buffer memory, and output synchronizing signal, indicating these output data is information symbol; In addition all states of other, output are all indicated synchronously and are not received useful signal.
The fast Fourier transform function of receive data is finished in FFT unit 202.When the data of importing this unit into are training symbol, the frequency spectrum data after fast Fourier transform will import carrier estimation unit 205 into; When the data of importing this unit into are information symbol, the frequency spectrum data after fast Fourier transform will import data screening unit 203 into.
Under ideal case, the ofdm communication bandwidth is approximately rectangle, and the starting point of rectangle and terminal point be low-limit frequency and the highest frequency of corresponding bandwidth respectively.But after signal transmitted through wireless channel, owing to disturbing and multipath effect, final frequency spectrum graphics and ideal rectangle difference were very large, are unfavorable for the differentiation of bandwidth.Small echo separates and reconfiguration unit 205a at first adopts the Haar small echo that the frequency spectrum that receives is carried out separating treatment, obtains changing in the frequency spectrum part of violent (details) and the part of relative level and smooth (roughly).Then adopt above-mentioned smoothed data that frequency spectrum is reconstructed, finally obtain approximate rectangular frequency spectrum.
Known Cyclic Prefix is that the training symbol by a plurality of repetitions consists of, and therefore, the spectrum information that each training symbol obtains after through FFT conversion ideally is identical.Two groups of identical training symbols behind complicated wireless channel, carry out respectively the FFT conversion to it, obtain respectively the frequency spectrum { f that disperses
A1, f
A2..., f
Ai..., f
Aj..., f
AnAnd { f
B1, f
B2..., f
Bi..., f
Bj..., f
Bn, wherein subscript i, j are correct communication bandwidth Origin And Destination.
In two groups of frequency spectrum datas, get at random respectively two point (f
Ae, f
Af) and (f
Be, f
Bf), obtain two groups of frequency spectrum data { f that bandwidth is identical
Ae..., f
AfAnd { f
Be..., f
Bf, above two groups of data are carried out cross-correlation operation obtain correlation ConvAB.Experiment showed, that working as starting point is respectively (f
Ai, f
Aj) and (f
Bi, f
Bj) time, the cross correlation value that obtains is maximum.
Frequency spectrum cross-correlation unit 205b carries out the cross-correlation of different starting points to the Cyclic Prefix frequency spectrum data that receives based on above-mentioned principle, finally obtain one group of bandwidth that bandwidth namely is this communication of correlation maximum.
Channel idle bandwidth estimation unit 206 is used for estimating the channel available bandwidth resources.Whether this unit is monitored the edge bandwidth power beyond this communication bandwidth in real time, take to judge the edge bandwidth.If free time surpasses an OFDM frame length, think that then this edge bandwidth is idle.
As shown in Figure 8, channel idle bandwidth estimation unit is comprised of edge bandwidth power density integrator 206a, noise gate identifying unit 206b and free time computing unit 206c.The internal register of noise gate comparator 206b, preserving channel does not have the signal noise power P in when transmission
NoiseThis comparator is with the power P of input
InWith P
NoiseCompare, work as P
In1.5P
NoiseThe time, comparator output bandwidth Seize ACK message; Work as P
In＜1.5P
NoiseThe time, comparator output bandwidth idle signal.Edge bandwidth power density integrator 206a will carry out integration, the edge calculation bandwidth power to the edge bandwidth power density beyond this communication bandwidth.And the performance number that calculates sent to noise gate comparing unit 206b, when receiving the bandwidth occupancy signal that is fed back by noise gate comparing unit 206b, edge bandwidth power density integrator 206a will reduce the integration bandwidth, and again continue rated output and export noise gate comparing unit 206b to.When receiving the bandwidth idle signal that is fed back by noise gate comparing unit 206b, edge bandwidth free time computing unit 206c will record current idle bandwidth information, and beginning cumulative bandwidth free time, if this bandwidth remains idle condition within the whole OFDM information frame time, carrier wave Change Strategy unit 208 will send feedback information to transmitter, improves signal bandwidth.
Because the frequency spectrum data band of FFT unit 202 outputs is wider than when time signal of communication bandwidth, the entrained data of the bandwidth that exceeds not are the data that transmitter sends.The bandwidth information that data screening unit 203 will estimate according to carrier estimation unit 205 filters out this communication bandwidth with interior data, and will be with outer data to send to channel idle bandwidth estimation unit 206, is used for the estimated edge bandwidth power.
The contrary decode procedure of transmitter stage casing manager 101, symbol adder 102,103 3 unit of map unit will be finished in Data Post unit 204, namely separate 16QAM mapping, deconvolution coding, deinterleaving coding, descrambling code.
Claims (8)
1. the OFDM transmitter and receiver of bandwidth varying, be used for the frame ofdm signal that sending and receiving is made of effective information symbol and Cyclic Prefix, it is characterized in that, described transmitter 100 can dynamically be adjusted the carrier wave number according to the communication bandwidth change feedback information that described receiver 200 provides, thereby the control communication bandwidth dynamically changes transfer rate of information simultaneously;
Described transmitter 100 comprises: segment management device 101, symbol adder 102, map unit 103, ofdm signal generation unit 104, Frame Size Adjustment unit 105, carrier wave adjustment unit 106, carrier number memory cell 107; Wherein, segment management device 101 links to each other with symbol adder 102 with Frame Size Adjustment unit 105, and according to from the symbol internal information figure place of Frame Size Adjustment unit 105, the baseband signal that host computer is transmitted is by the information bit segment processing; Symbol adder 102, input connects segment management device 101, and output connects map unit 103, and the packet that is sended over by segment management device 101 is carried out forward error correction coding and convolutional encoding; Map unit 103, input connects symbol adder 102, and output connects ofdm signal generation unit 104, adopts 16QAM, and with 4 ' 0,1 ' signal is transformed to a bit 1 corresponding symbol in 16 points on the IQ plane; Ofdm signal generation unit 104 links to each other with carrier wave adjustment unit 106 with map unit 103, sends as transmitting after the frequency spectrum data conversion that will consist of from data and the pilot data of map unit 103; Frame Size Adjustment unit 105 links to each other with carrier wave adjustment unit 106 with segment management device 101, the computing information symbol lengths, and to host computer feedback information bit rate adjustment signal; Carrier wave adjustment unit 106 links to each other with ofdm signal generation unit 104, Frame Size Adjustment unit 105 and carrier number memory cell 107, is used for adjusting communication bandwidth and number of carriers; Carrier number memory cell 107 links to each other with carrier wave adjustment unit 106, is used for storing the bandwidth information of current communication;
Described receiver 200 comprises: Cyclic Prefix detecting unit 201, FFT unit 202, data screening unit 203, Data Post unit 204, carrier estimation unit 205, channel idle bandwidth estimation unit 206, carrier information memory cell 207, carrier wave Change Strategy unit 208; Wherein, Cyclic Prefix detecting unit 201, input connects antenna, and output connects FFT unit 202, for detection of the Cyclic Prefix that is positioned at each OFDM frame; FFT unit 202, input connects Cyclic Prefix detecting unit 201, and output connects respectively data screening unit 203 and carrier estimation unit 205, is used for carrying out to received signal fast Fourier transform; Data screening unit 203, input connects FFT unit 202, and output connects respectively Data Post unit 204 and channel idle bandwidth estimation unit 206, is used for filtering out the data that are positioned at communication band, to be with simultaneously outer data to send to channel idle bandwidth estimation unit 206, in order to estimate out-of-band power; Data Post unit 204 links to each other with data screening unit 203, is used for separating the 16QAM mapping and separates forward error correction coding; Carrier estimation unit 205, input connects FFT unit 202, and ripple information memory cell 207 is carried in output, is used for estimating this communication bandwidth and number of carriers; Channel idle bandwidth estimation unit 206, input connects data screening unit 203, and ripple Change Strategy unit 208 is carried in output, is used for the out of band spectrum resource of this communication band of Real-Time Monitoring; Carrier information memory cell 207 links to each other with data screening unit 203 with carrier estimation unit 205, is used for this communication bandwidth information of storage; Whether carrier wave Change Strategy unit 208 links to each other with channel idle bandwidth estimation unit 206, be used for the decision-making communication bandwidth and change.
2. the OFDM transmitter and receiver of bandwidth varying according to claim 1 is characterized in that, the carrier wave adjustment unit 106 of described transmitter 100 comprises carrier number determinant 106a and pilot tone adjustment unit 106b, wherein,
Carrier number determinant 106a, link to each other with carrier number memory cell 107 with the carrier wave Change Strategy unit 208 of pilot tone adjustment unit 106b, described receiver respectively, reception is from the bandwidth feedback information of receiver, read the carrier information in the carrier number memory cell 107, according to the bandwidth feedback information, carrier information done suitable adjustment and upgrade carrier information in the carrier number memory cell 107; Above-mentioned method of adjustment is: when communication bandwidth changes delta B, corresponding number of carriers is changed to Δ C=Δ B/S
BW, S wherein
BWFrequency interval for subcarrier;
Pilot tone adjustment unit 106b, link to each other with carrier number determinant 106a, ofdm signal generation unit 104 and Frame Size Adjustment unit 106 respectively, according to pilot number and the position of pilot tone in frequency band in the number of carriers adjustment transmission frame structure, pilot number is decided to be 1/16 of total number of subcarriers, and all pilot tones are evenly distributed in the whole communication bandwidth, adjust the result and send to respectively Frame Size Adjustment unit 106 and ofdm signal generation unit 104.
3. according to claim 1 or the OFDM transmitter and receiver of bandwidth varying claimed in claim 2, it is characterized in that, the Frame Size Adjustment unit 105 of described transmitter 100 comprises figure place computing unit 105a and the interior transmission of frame total information figure place computing unit 105b in the symbol; Wherein,
Figure place computing unit 105a in the symbol, respectively with frame in transmission total information figure place computing unit 105b, carrier wave adjustment unit 106 link to each other with segment management device 101, the available carrier wave that provides according to carrier number adjustment unit 106 is counted calculated signals and is gone out transmissible information bit number in each symbol;
Transmission total information figure place computing unit 105b in the frame, link to each other with figure place computing unit 105a in the symbol, the symbol internal information figure place that provides according to figure place computing unit 105a in the symbol, calculate in the frame of reaction instant messages speed and can transmit the total information figure place, and information rate adjusts the feedback information of information bit transmission rate to host computer accordingly.
4. according to claim 1 or the OFDM transmitter and receiver of bandwidth varying claimed in claim 2, it is characterized in that, the bandwidth varying ofdm signal generation unit 104 of described transmitter 100 comprises pilot tone and training symbol maker 104a, data and pilot frequency distribution device 104b, IFFT unit 104c and protection interval adding device 104d; Wherein,
Pilot tone and training symbol maker 104a, output connects data and pilot frequency distribution device, before data symbol sends, the generation cycle prefix signal, and when data symbol sends, generate pilot frequency information;
Data and pilot frequency distribution device 104b, link to each other with map unit 103 with training symbol maker 104a with IFFT unit, pilot tone respectively, to press certain arrangement mode composition frequency spectrum data bag from the information data of map unit 103 and from the pilot data of pilot tone and training symbol maker 104a, send IFFT unit 104c to;
IFFT unit 104c, link to each other with protection interval adding device 104d with pilot frequency distribution device 104b with data, to carry out quick inverse Fourier transform from the frequency spectrum data bag of data and pilot frequency distribution device 104b, and parallel data be converted to export protection interval adding device behind the serial time domain data to;
Protection interval adding device 104d, 104c links to each other with the IFFT unit, adds between two discontinuous information symbols of the serial time domain data of sending here to IFFT unit 104c and protects the interval.
5. the OFDM transmitter and receiver of bandwidth varying according to claim 1 is characterized in that, the carrier estimation unit 205 of described receiver 200 comprises that small echo separates and reconfiguration unit 205a and frequency spectrum cross-correlation unit 205b; Wherein,
Small echo separates and reconfiguration unit 205a, link to each other with described FFT unit 202 with frequency spectrum cross-correlation unit 205b, adopt the Haar small echo that the frequency spectrum data from FFT unit 202 is carried out separating treatment, obtain changing in the frequency spectrum violent part and relative level and smooth part, adopt wherein level and smooth data division that frequency spectrum is reconstructed, finally obtain approximate rectangular frequency spectrum;
Frequency spectrum cross-correlation unit 205b, separate with reconfiguration unit 205a with small echo and to link to each other with carrier information memory cell 207, to the Cyclic Prefix frequency spectrum data after being processed with reconfiguration unit 205a by the small echo separation, carry out the cross-correlation of different starting points, finally obtain one group of bandwidth that bandwidth namely is this communication of correlation maximum.
6. according to claim 1 or the OFDM transmitter and receiver of bandwidth varying claimed in claim 5, it is characterized in that, the channel idle bandwidth estimation unit 206 of described receiver 200 comprises edge bandwidth power density integrator 206a, noise gate comparing unit 206b and free time computing unit 206c; Wherein,
Edge bandwidth power density integrator 206a links to each other with data screening unit 203 with noise gate comparing unit 206b, will carry out integration, the edge calculation bandwidth power to the edge bandwidth power density beyond this communication bandwidth;
Noise gate comparing unit 206b links to each other with edge bandwidth power density integrator 206a with free time computing unit 206c, with edge bandwidth power P
InWith noise power P
NoisCompare, work as P
In1.5P
NoiseThe time, the output bandwidth Seize ACK message; Work as P
In＜1.5P
NoiseThe time, the output bandwidth idle signal if free time surpasses an OFDM frame length, thinks that then this edge bandwidth is idle;
Free time computing unit 206c, link to each other with carrier wave Change Strategy unit 208 with noise gate comparing unit 206b, when receiving the bandwidth idle signal that is fed back by described noise gate comparing unit, record current idle bandwidth information, and beginning cumulative bandwidth free time, if this bandwidth remains idle condition within the whole OFDM information frame time, carrier wave Change Strategy unit 208 will send feedback information to transmitter, improves signal bandwidth.
7. it is characterized in that according to claim 1 or the OFDM transmitter and receiver of bandwidth varying claimed in claim 5:
Utilize the frequency spectrum related algorithm of cycle of training in the Cyclic Prefix, the identification communication bandwidth.
8. it is characterized in that according to claim 1 or the OFDM transmitter and receiver of bandwidth varying claimed in claim 5:
Adopt the method for wavelet transformation that frequency spectrum data is decomposed, utilize level and smooth part, reconstruct the frequency spectrum close to ideal case.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107276943A (en) * | 2016-04-08 | 2017-10-20 | 深圳超级数据链技术有限公司 | Time synchronization method, device and system |
| CN110337800A (en) * | 2017-02-06 | 2019-10-15 | 弗劳恩霍夫应用研究促进协会 | Receiver, transmitter, the communication system for subband communication and the method for subband communication |
| CN111950941A (en) * | 2020-10-13 | 2020-11-17 | 垒途智能教科技术研究院江苏有限公司 | Industrial design system for improving interaction experience and interaction method thereof |
| CN112188550A (en) * | 2020-09-28 | 2021-01-05 | 展讯通信（上海）有限公司 | Data transmission method, wireless access point and computer readable storage medium |
| CN112839000A (en) * | 2020-12-30 | 2021-05-25 | 北京神经元网络技术有限公司 | High-speed industrial bus system with variable symbol bandwidth and method for changing symbol bandwidth |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101005335A (en) * | 2006-01-19 | 2007-07-25 | 中兴通讯股份有限公司 | Modulation method for transmitting antenna selection and adaption in multiple input and multiple output frequency-division multiplex system |
| EP2120377A1 (en) * | 2007-02-09 | 2009-11-18 | Sharp Kabushiki Kaisha | Ofdm transmitter and ofdm receiver |
| CN101888363A (en) * | 2010-06-22 | 2010-11-17 | 北京大学 | Signal demodulation method in OFDM receiver and OFDM receiver |
| CN102318304A (en) * | 2008-01-22 | 2012-01-11 | Nxp股份有限公司 | Post-DTF/FFT time tracking algorithm for OFDM receivers |
-
2012
- 2012-11-28 CN CN201210496763.0A patent/CN103023850B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101005335A (en) * | 2006-01-19 | 2007-07-25 | 中兴通讯股份有限公司 | Modulation method for transmitting antenna selection and adaption in multiple input and multiple output frequency-division multiplex system |
| EP2120377A1 (en) * | 2007-02-09 | 2009-11-18 | Sharp Kabushiki Kaisha | Ofdm transmitter and ofdm receiver |
| CN102318304A (en) * | 2008-01-22 | 2012-01-11 | Nxp股份有限公司 | Post-DTF/FFT time tracking algorithm for OFDM receivers |
| CN101888363A (en) * | 2010-06-22 | 2010-11-17 | 北京大学 | Signal demodulation method in OFDM receiver and OFDM receiver |
Non-Patent Citations (2)
| Title |
|---|
| XIAOFEI DONG ET AL: "Channel Estimation and Bit-loading in Wireless Multicarrier Systems Based on Decimated Signal Feedback", 《COMMUNICATIONS, 2006. ICC "06. IEEE INTERNATIONAL CONFERENCE ON》 * |
| 王鹏: "可扩展带宽OFDM系统的硬件设计和实现", 《中国优秀硕士学位论文全文数据库（电子期刊）》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107276943A (en) * | 2016-04-08 | 2017-10-20 | 深圳超级数据链技术有限公司 | Time synchronization method, device and system |
| CN107276943B (en) * | 2016-04-08 | 2020-01-07 | 深圳光启合众科技有限公司 | Timing synchronization method, device and system |
| CN110337800A (en) * | 2017-02-06 | 2019-10-15 | 弗劳恩霍夫应用研究促进协会 | Receiver, transmitter, the communication system for subband communication and the method for subband communication |
| CN112188550A (en) * | 2020-09-28 | 2021-01-05 | 展讯通信（上海）有限公司 | Data transmission method, wireless access point and computer readable storage medium |
| WO2022062811A1 (en) * | 2020-09-28 | 2022-03-31 | 展讯通信（上海）有限公司 | Data transmission method, wireless access point, and computer readable storage medium |
| CN111950941A (en) * | 2020-10-13 | 2020-11-17 | 垒途智能教科技术研究院江苏有限公司 | Industrial design system for improving interaction experience and interaction method thereof |
| CN111950941B (en) * | 2020-10-13 | 2021-02-12 | 垒途智能教科技术研究院江苏有限公司 | Industrial design system for improving interaction experience and interaction method thereof |
| WO2022077536A1 (en) * | 2020-10-13 | 2022-04-21 | 垒途智能教科技术研究院江苏有限公司 | Industrial design system for improving interactive experience and interaction method thereof |
| CN112839000A (en) * | 2020-12-30 | 2021-05-25 | 北京神经元网络技术有限公司 | High-speed industrial bus system with variable symbol bandwidth and method for changing symbol bandwidth |
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|---|---|
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