CN102938751A - Method and device for windowing time domains of time domain synchronization orthogonal frequency division multiplexing system - Google Patents
Method and device for windowing time domains of time domain synchronization orthogonal frequency division multiplexing system Download PDFInfo
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Abstract
The invention discloses a method and device for windowing time domains of a time domain synchronization orthogonal frequency division multiplexing system. The method comprises the steps of combining a training sequence and corresponding inverse discrete Fourier transform data blocks according to system transmission parameters to generate signal frames of the time domain synchronization orthogonal frequency division multiplexing system, defining a current frame into a frame, and defining a signal frame before and after the frame into a front frame and a rear frame; generating a circulating suffix of the frame, and copying the circulating suffix of the frame after a frame data block; performing time domain windowing on former W/2 symbols of the frame training sequence and later W/2 symbols of the circulating suffix, wherein the W is windowing length; and successively adding the W/2 symbols of the frame training sequence subjected to time domain windowing and the W/2 symbols of a former frame circulating suffix subjected to time domain windowing. The method and device for windowing time domains of the time domain synchronization orthogonal frequency division multiplexing system are simple in achieving process and low in complexity, improve transmission rate within a specified frequency range, and can simultaneously improve flexibility, effectiveness and reliability of signal transmission and spectral efficiency.
Description
Technical field
The present invention relates to digital signal transmission technique field, particularly time-domain windowed method and the device thereof of a kind of time-domain synchronization OFDM (Time Domain Synchronous OFDM, TDS-OFDM) system.
Background technology
The problem that present broadband wireless communication technique mainly solves is how to improve reliably transmission rate in limited bandwidth, need further to promote spectrum efficiency for limited frequency spectrum resource, clearly proposed the requirement that the uplink and downlink link spectral efficiency is respectively 15bit/Hz and 30bit/Hz in the standardization of LTE-A.OFDM (OFDM:Orthogonal FrequencyDivision Multiplexing) technology is because spectral efficient and the excellent ability of anti-multipath fading extensively used, and is considered to one of current the most promising transmission technology.
Yet, for block transmission system, although the duration of data block be far longer than the duration of single symbol, under large time delay expansion passage, still there are the IBI(Inter Block Interference that can not ignore, inter-block-interference between the time-domain data blocks).A kind of effective ways of block transmission system antagonism IBI are to add GI(Guard Interval between time-domain data blocks in the prior art; the protection interval); the maximum multipath time-delay of passage is no more than in the situation of GI length, can not produce interference between the time-domain data blocks.Fill the variety classes of content according to GI, exist multiple GI filling technique, comprising CP(Cyclic Prefix, Cyclic Prefix) filling technique, ZP(Zero Padding, zero padding) technology, with TS(Training Sequence, training sequence) filling technique etc.Wherein the CP filling technique successful Application to IEEE802.11a WLAN (wireless local area network), ground numerical digit video broadcasting (Digital VideoBroadcasting-Terrestrial, DVB-T) and in second generation standard DVB-T2 system and IEEE1901 and the G.hn broadband power line communication system, its frame structure as shown in Figure 1; Based on PN(Pseudo-random Noise, pseudo noise) method of Sequence Filling is the special case of TS filling technique, a key character that belongs to the TDS-OFDM system, this technology successful Application arrives Chinese terrestrial DTV transmission standard (Digital Television Multimedia Broadcast, DTMB) in, its frame structure as shown in Figure 2.
In broadband connections, there are some frequency ranges to reserve for services such as ham radio, Long-distance Control and aerospace communications, therefore can not be subject to stronger electromagnetic interference; Yet some relies on the communication of transmission medium, such as PLC(Power Line Communication, power line communication) can't accomplish to shield fully to external world, have some signal couplings and go out; Disturb for the signal that reduces coupling produces above-mentioned critical services, generally can carry out trap to reserved band and process.In the transmission system based on OFDM, two kinds of common trap methods are generally arranged: the first is to send complete OFDM symbol, rely on notch filter (Notched Filter, can use IIR or FIR to realize), but changeable, uncertain stronger situation that the notch filter of preset parameter can not well conform is such as the communication environment of PLC.The second is directly to close the parton carrier wave around the corresponding band among the OFDM, disturbs to reduce as far as possible but need to allow this moment subcarrier roll-off fast at frequency domain, improves simultaneously the system spectrum utilance.
Show after deliberation, cooperate suitable windowing process in time domain, can allow the subcarrier of OFDM roll-off fast at frequency domain, effectively reduce simultaneously the subcarrier secondary lobe, improve the spectrum efficiency of system.Therefore, to the digital-communications transmission system based on the TDS-OFDM frame structure, be necessary to improve by rational frame structure design, suitable windowing process flexibility, validity and the reliability of signal transmission, further promote spectrum efficiency, reduce signal transmission interference to external world on the special frequency channel.
Summary of the invention
The technical problem that (one) will solve
The object of the invention is to provide a kind of time-domain windowed method and device based on time-domain synchronization OFDM (TimeDomain Synchronous OFDM, TDS-OFDM) system, to improve the spectrum efficiency of system.
(2) technical scheme
For addressing the above problem, the invention provides a kind of time-domain windowed method of time-domain synchronous orthogonal frequency-division multiplexing system, may further comprise the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
Preferably, among the described step S1, described training sequence comprises the cyclic extensions of m sequence, Gold sequence, Legendre sequence, Walsh sequence, Golay sequence, above-mentioned sequence or blocks, take and the discrete Fourier transform territory as the cyclic extensions of above-mentioned sequence or above-mentioned sequence or the sequence of blocking.
Preferably, described training sequence is two sections identical known arrays.
Preferably, among the described step S2, described cyclic suffix is front L symbol of described frame data piece, and L is positive integer.
Preferably, among the described step S2, described cyclic suffix is front L symbol of described training sequence, and L is positive integer.
Among the described step S3, described time-domain windowed is treated to: described front W/2 the symbol of frame training sequence multiply by front W/2 coefficient of corresponding window function successively, and rear W/2 symbol of described frame cyclic suffix multiply by rear W/2 coefficient of corresponding window function successively.
Further, after described step S4, also comprise:
S5, the signal after time-domain windowed processed carry out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
Preferably, described time domain window function comprises raised cosine roll off window, Hamming window, Hanning window and Caesar's window.
Preferably, described window length W is subjected to described data block length, training sequence length or cyclic suffix length constraint, and it is no more than 1/16 of data block length, perhaps is no more than time-domain training sequence length, perhaps is no more than the twice of cyclic suffix length.
The present invention also provides a kind of time-domain windowed device of time-domain synchronous orthogonal frequency-division multiplexing system, and this device comprises:
Time-domain synchronization OFDM frame generation module is used for according to the system transmissions parameter, produces the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence;
The cyclic suffix generation module, link to each other with described time-domain synchronization OFDM frame generation module, front L the symbol that is used for front L symbol of these frame data piece or this frame training sequence copies to after the current frame data piece, produces the cyclic suffix of this frame, and L is positive integer;
The time-domain windowed module links to each other with described cyclic suffix generation module, is used for rear W/2 symbol of the front W/2 of this a frame training sequence symbol and this frame cyclic suffix carried out the time-domain windowed processing, and W is window length;
The time domain laminating module links to each other with described time-domain windowed module, after front W/2 symbol after being used for this frame training sequence processed through time-domain windowed and the processing of front frame cyclic suffix process time-domain windowed after W/2 symbol in time domain successively addition;
The subsequent treatment module links to each other with described time domain laminating module, is used for the signal after the time-domain windowed processing is carried out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
(3) beneficial effect
Based on the present invention program's time-domain windowed method and device, communication system can obtain higher spectrum efficiency.Implementation procedure of the present invention is simple, complexity is low, can effectively use in the wireless transfer channel environment of complexity.
Description of drawings
Fig. 1 is a kind of schematic diagram of CP-OFDM frame structure in the prior art;
Fig. 2 is a kind of schematic diagram of TDS-OFDM frame structure in the prior art;
Fig. 3 is the flow chart of the inventive method;
Fig. 4 is a kind of frame structure schematic diagram based on TDS-OFDM that the present invention proposes;
Fig. 5 is a kind of frame structure windowing method schematic diagram based on TDS-OFDM that the present invention proposes;
Fig. 6 is the production method schematic diagram of the frame cyclic suffix among the embodiment of the invention one and three;
Fig. 7 is the production method schematic diagram of the frame cyclic suffix among the embodiment of the invention two and four;
Fig. 8 is the stacking method schematic diagram of the consecutive frame of the embodiment of the invention;
Fig. 9 is the spectrum efficiency design sketch of a kind of frame structure windowing method based on TDS-OFDM of proposing of the present invention;
Figure 10 is the structure chart of apparatus of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples are used for explanation the present invention, but are not used for limiting the scope of the invention.
Fig. 3 is the flow chart of the inventive method, specifically may further comprise the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
Preferably, among the described step S1, described training sequence comprises the cyclic extensions of m sequence, Gold sequence, Legendre sequence, Walsh sequence, Golay sequence, above-mentioned sequence or blocks, take and the discrete Fourier transform territory as the cyclic extensions of above-mentioned sequence or above-mentioned sequence or the sequence of blocking.
Preferably, described training sequence is two sections identical known arrays.
Preferably, among the described step S2, described cyclic suffix is front L symbol of described frame data piece, and L is positive integer.
Preferably, among the described step S2, described cyclic suffix is front L symbol of described training sequence, and L is positive integer.
Among the described step S3, described time-domain windowed is treated to: described front W/2 the symbol of frame training sequence multiply by front W/2 coefficient of corresponding window function successively, and rear W/2 symbol of described frame cyclic suffix multiply by rear W/2 coefficient of corresponding window function successively.
Further, after described step S4, also comprise:
S5, the signal after time-domain windowed processed carry out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
Preferably, described time domain window function comprises raised cosine roll off window, Hamming window, Hanning window and Caesar's window.
Preferably, described window length W is subjected to described data block length, training sequence length or cyclic suffix length constraint, and it is no more than 1/16 of data block length, perhaps is no more than time-domain training sequence length, perhaps is no more than the twice of cyclic suffix length.
In described ofdm system, training sequence and the OFDM data block that fill at the protection interval form a signal frame, and the training sequence of filling between data block is comprised of two sections identical sequences in the present embodiment.Frame structure windowing method specifically comprises the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
The training sequence that the present embodiment adopts is comprised of two sections identical sequences.Wherein, every section its discrete Fourier transform territory of sequence is that length is 256 m sequence, i.e. N1=N2=256.This sequence is the m sequence on 8 rank, is realized by a Fibonacci Linear feedback shift register (LFSR).Its proper polynomial is defined as x
8+ x
6+ x
5+ x+1.Then above-mentioned m sequence is done length and is 256 IDFT(Inverse Discrete Fourier Transform, the discrete fourier inverse transformation) to become length be 256 time domain sequences.Then two sections identical time domain sequences are constituted total length and are 512 training sequence.
In the present embodiment, each frame transmission 4096 data symbols, i.e. N=4096.When generating training sequence, produce the data to be transmitted bit of this frame, through FEC(ForwardError Coding, forward error correction coding) and interweave, then carrying out constellation mapping and obtain 4096 data symbol of this frame, is 4096 time-domain data blocks through obtaining length behind the IDFT.
In time domain, training sequence is placed the rear TDS-OFDM system signal frame that produces this frame of before combination of time-domain data blocks.
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
In the present embodiment, preferably, parameter L elects 32 as, and front 32 symbols of these frame data piece are copied to after these frame data piece, produces the cyclic suffix of this frame, as shown in Figure 6.The total length of this sample frame has just become 256 * 2+4096+32=4640.
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
In the present embodiment, take into account simultaneously transmission rate in order to reduce better out-of-band power raising spectrum efficiency, preferably, adopting the beta parameter is that Caesar's window of 10 is as the window function of windowing process, window length is W, W is subjected to the constraint of data block length, training sequence length and cyclic suffix length constraint, and in the present embodiment, W gets 64.
The process that time-domain windowed is processed is as follows: front 32 symbols (front 32 symbols of this frame training sequence) of this frame be multiply by respectively front 32 coefficients of window, rear 32 symbols (rear 32 symbols of cyclic suffix) of this frame be multiply by respectively rear 32 coefficients of window.
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
In the present embodiment, owing to being the frame structure of continuous system, can obtain by the partial stack of consecutive frame certain efficiency of transmission: 32 symbol aligned after front 32 symbols after this frame training sequence is processed through time-domain windowed are processed through time-domain windowed with front frame cyclic suffix and in time domain successively addition, as shown in Figure 8; Correspondingly, with this frame cyclic suffix through 32 symbols after after the windowing process with after the frame training sequence after processing through time-domain windowed front 32 symbol aligned and in time domain successively addition.Through after such processing, just can offset to a certain extent the reduction of the efficiency of transmission that time-domain windowed brings, so that the actual transmissions symbolic number of every frame equivalence is 256 * 2+4096=4608.Frequency spectrum effect contrast figure after passing through windowing process and not passing through windowing process as shown in Figure 9.
In the present embodiment, after consecutive frame is carried out overlap-add procedure, carry out successively molding filtration, Digital Up Convert and digital-to-analogue conversion, signal is sent.
In described ofdm system, training sequence and the OFDM data block that fill at the protection interval form a signal frame, and the training sequence of filling between data block is comprised of the different sequence of two segment length in the present embodiment.Frame structure windowing method specifically comprises the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
The training sequence that the present embodiment adopts is comprised of the different sequence of two segment length.Wherein, the first paragraph sequence is the cyclic extensions of second segment sequence, and the second segment sequence is that length is 255 m sequence, and the first paragraph sequence is the sequence that rear 165 symbols of second segment sequence form, i.e. N1=165, N2=255.Then these two sections time domain sequences are constituted total length and are 420 training sequence.
In the present embodiment, each frame transmission 3072 data symbols, i.e. N=3072.When generating training sequence, produce the data to be transmitted bit of this frame, through FEC with interweave, then carry out 3072 data symbol that constellation mapping obtains this frame, be 3072 time-domain data blocks through obtaining length behind the IDFT.
In time domain, training sequence is placed the rear TDS-OFDM system signal frame that produces this frame of before combination of time-domain data blocks.
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
In the present embodiment, preferably, parameter L elects 64 as, and front 64 symbols of this frame training sequence are copied to after these frame data piece, produces the cyclic suffix of this frame, as shown in Figure 7.The total length of this sample frame has just become 165+255+3072+64=3556.
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
In the present embodiment, take into account simultaneously transmission rate in order to reduce better out-of-band power raising spectrum efficiency, preferably, adopt Hamming window as the window function of windowing process, window length is W, and W is subject to the constraint of data block length, be no more than 1/16 of data block length, in the present embodiment, W gets 64.
The process that time-domain windowed is processed is as follows: front 32 symbols (front 32 symbols of this frame training sequence) of this frame be multiply by respectively front 32 coefficients of window, rear 32 symbols (rear 32 symbols of cyclic suffix) of this frame be multiply by respectively rear 32 coefficients of window.
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
In the present embodiment, owing to being the frame structure of continuous system, can obtain by the partial stack of consecutive frame certain efficiency of transmission: 32 symbol aligned after front 32 symbols after this frame training sequence is processed through time-domain windowed are processed through time-domain windowed with front frame cyclic suffix and in time domain successively addition, as shown in Figure 8; Correspondingly, with this frame cyclic suffix through 32 symbols after after the windowing process with after the frame training sequence after processing through time-domain windowed front 32 symbol aligned and in time domain successively addition.Through after such processing, just can offset to a certain extent the reduction of the efficiency of transmission that time-domain windowed brings, so that the actual transmissions symbolic number of every frame equivalence is 165+255+3072=3492.
In the present embodiment, after consecutive frame is carried out overlap-add procedure, carry out successively molding filtration, digital-to-analogue conversion and simulation up-conversion, signal is sent.
Embodiment 3
Embodiment 3 specifically describes one and has multi-frame structure and based on the workflow of the frame structure windowing method of continuous T DS-OFDM.In the present embodiment frame structure as shown in Figure 4, the windowing method as shown in Figure 5, each parametric description is with embodiment 1.
In described ofdm system, training sequence and the OFDM data block that fill at the protection interval form a signal frame, and the training sequence of filling between data block is comprised of two sections identical sequences in the present embodiment.Frame structure windowing method specifically comprises the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
The training sequence that the present embodiment adopts is comprised of two sections identical sequences.Wherein, the discrete Fourier transform territory of every section sequence is that length is 512 Walsh sequence, i.e. N1=N2=512.Then above-mentioned Walsh sequence being done length and be 512 IDFT, to become length be 512 time domain sequences.Then two sections identical time domain sequences are constituted total length and are 1024 training sequence.
In the present embodiment, each frame transmission 8192 data symbols, i.e. N=8192.When generating training sequence, produce the data to be transmitted bit of this frame, through FEC with interweave, then carry out 8192 data symbol that constellation mapping obtains this frame, be 8192 time-domain data blocks through obtaining length behind the IDFT.
In time domain, training sequence is placed the rear TDS-OFDM system signal frame that produces this frame of before combination of time-domain data blocks.
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
In the present embodiment, preferably, parameter L elects 128 as, and front 128 symbols of these frame data piece are copied to after these frame data piece, produces the cyclic suffix of this frame, as shown in Figure 6.The total length of this sample frame has just become 512 * 2+8192+128=9344.
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
In the present embodiment, take into account simultaneously transmission rate in order to reduce better out-of-band power raising spectrum efficiency, preferably, adopt Hanning window as the window function of windowing process, window length is W, and W is subject to training the constraint of length, be no more than the length of training sequence, in the present embodiment, W gets 128.
The process that time-domain windowed is processed is as follows: front 64 symbols (front 64 symbols of this frame training sequence) of this frame be multiply by respectively front 64 coefficients of window, rear 64 symbols (rear 64 symbols of cyclic suffix) of this frame be multiply by respectively rear 64 coefficients of window.
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
In the present embodiment, owing to being the frame structure of continuous system, can obtain by the partial stack of consecutive frame certain efficiency of transmission: 64 symbol aligned after front 64 symbols after this frame training sequence is processed through time-domain windowed are processed through time-domain windowed with front frame cyclic suffix and in time domain successively addition, as shown in Figure 8; Correspondingly, with this frame cyclic suffix through 64 symbols after after the windowing process with after the frame training sequence after processing through time-domain windowed front 64 symbol aligned and in time domain successively addition.Through after such processing, just can offset to a certain extent the reduction of the efficiency of transmission that time-domain windowed brings, so that the actual transmissions symbolic number of every frame equivalence is 512 * 2+8192+128-64=9280.
In the present embodiment, after consecutive frame is carried out overlap-add procedure, carry out molding filtration, Digital Up Convert and digital-to-analogue conversion successively after, signal is sent.
Embodiment 4
Embodiment 4 specifically describes one and has multi-frame structure and based on the workflow of the frame structure windowing method of burst TDS-OFDM.In the present embodiment frame structure as shown in Figure 4, the windowing method as shown in Figure 5, each parametric description is with embodiment 1.
In described ofdm system, training sequence and the OFDM data block that fill at the protection interval form a signal frame, and the training sequence of filling between data block is comprised of two sections identical sequences in the present embodiment.Frame structure windowing method specifically comprises the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
The training sequence that the present embodiment adopts is comprised of two sections identical sequences.Wherein, every section sequence is that length is 512 Legendre sequence, i.e. N1=N2=512.Then two sections identical combined sequence are consisted of total lengths and are 1024 time-domain training sequence.
In the present embodiment, each frame transmission 8192 data symbols, i.e. N=8192.When generating training sequence, produce the data to be transmitted bit of this frame, through FEC with interweave, then carry out 8192 data symbol that constellation mapping obtains this frame, be 8192 time-domain data blocks through obtaining length behind the IDFT.
In time domain, time-domain training sequence is placed the rear TDS-OFDM system signal frame that produces this frame of before combination of time-domain data blocks.
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
In the present embodiment, parameter L elects 64 as, and front 64 symbols of this frame training sequence are copied to after the current frame data piece, produces the cyclic suffix of this frame, as shown in Figure 7.The total length of this sample frame has just become 512 * 2+8192+64=9280.
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
In the present embodiment, take into account simultaneously transmission rate in order to reduce better out-of-band power raising spectrum efficiency, preferably, adopt Hanning window as the window function of windowing process, window length is W, and W is subject to the constraint of cyclic suffix length, be no more than the twice of cyclic suffix length, in the present embodiment, W gets 32.
The process that time-domain windowed is processed is as follows: front 32 symbols (front 32 symbols of this frame training sequence) of these frame data be multiply by respectively front 32 coefficients of window, rear 32 symbols (rear 32 symbols of datacycle suffix) of these frame data be multiply by respectively rear 32 coefficients of window.
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
In the present embodiment, owing to being the frame structure of burst system, therefore do not have consecutive frame to carry out partial stack, so this step is omitted.
In the present embodiment, frame is carried out molding filtration, digital-to-analogue conversion and simulation up-conversion successively, signal is sent.
Figure 10 is the structure chart of apparatus of the present invention, and the present invention also provides a kind of time-domain windowed device of time-domain synchronous orthogonal frequency-division multiplexing system, and this device comprises:
Time-domain synchronization OFDM (TDS-OFDM) frame generation module is used for according to the system transmissions parameter, produces time-domain synchronization OFDM (TDS-OFDM) system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence;
The cyclic suffix generation module, link to each other with described time-domain synchronization OFDM frame generation module, front L the symbol that is used for front L symbol of these frame data piece or this frame training sequence copies to after the current frame data piece, produces the cyclic suffix of this frame, and L is positive integer;
The time-domain windowed module links to each other with described cyclic suffix generation module, is used for rear W/2 symbol of the front W/2 of this a frame training sequence symbol and this frame cyclic suffix carried out the time-domain windowed processing, and W is window length;
The time domain laminating module links to each other with described time-domain windowed module, after front W/2 symbol after being used for this frame training sequence processed through time-domain windowed and the processing of front frame cyclic suffix process time-domain windowed after W/2 symbol in time domain successively addition;
The subsequent treatment module links to each other with described time domain laminating module, is used for the signal after the time-domain windowed processing is carried out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvement and replacement, these improvement and replacement also should be considered as protection scope of the present invention.
Claims (10)
1. the time-domain windowed method of a time-domain synchronous orthogonal frequency-division multiplexing system is characterized in that, may further comprise the steps:
S1, according to the system transmissions parameter, produce the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence, current time-domain synchronization OFDM signal frame is defined as this frame, and its forward and backward signal frame is defined as front frame, rear frame successively;
S2, generate the cyclic suffix of this frame, and copy to after these frame data piece;
S3, rear W/2 symbol of the front W/2 of this a frame training sequence symbol and cyclic suffix carried out time-domain windowed process, wherein W is window length;
S4, front W/2 symbol after this frame training sequence processed through time-domain windowed and front frame cyclic suffix are passed through W/2 symbol after time-domain windowed is processed in time domain successively addition.
2. the method for claim 1, it is characterized in that, among the described step S1, described training sequence comprises the cyclic extensions of m sequence, Gold sequence, Legendre sequence, Walsh sequence, Golay sequence, above-mentioned sequence or blocks, take and the discrete Fourier transform territory as the cyclic extensions of above-mentioned sequence or above-mentioned sequence or the sequence of blocking.
3. the method for claim 1 is characterized in that, described training sequence is two sections identical known arrays.
4. the method for claim 1 is characterized in that, among the described step S2, described cyclic suffix is front L symbol of described frame data piece, and L is positive integer.
5. the method for claim 1 is characterized in that, among the described step S2, described cyclic suffix is front L symbol of described training sequence, and L is positive integer.
6. the method for claim 1, it is characterized in that, among the described step S3, described time-domain windowed is treated to: described front W/2 the symbol of frame training sequence multiply by front W/2 coefficient of corresponding window function successively, and rear W/2 symbol of described frame cyclic suffix multiply by rear W/2 coefficient of corresponding window function successively.
7. the method for claim 1 is characterized in that, further comprises after described step S4:
S5, the signal after time-domain windowed processed carry out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
8. such as claim 1 or 6 described methods, it is characterized in that, described time domain window function comprises raised cosine roll off window, Hamming window, Hanning window and Caesar's window.
9. such as claim 1 or 6 described methods, it is characterized in that, described window length W is subjected to described data block length, training sequence length or cyclic suffix length constraint, it is no more than 1/16 of data block length, perhaps be no more than time-domain training sequence length, perhaps be no more than the twice of cyclic suffix length.
10. the time-domain windowed device of a time-domain synchronous orthogonal frequency-division multiplexing system is characterized in that, this device comprises:
Time-domain synchronization OFDM frame generation module is used for according to the system transmissions parameter, produces the time-domain synchronous orthogonal frequency-division multiplexing system signal frame after the discrete fourier inverse transformation data block combinations with training sequence and correspondence;
The cyclic suffix generation module, link to each other with described time-domain synchronization OFDM frame generation module, front L the symbol that is used for front L symbol of these frame data piece or this frame training sequence copies to after the current frame data piece, produces the cyclic suffix of this frame, and L is positive integer;
The time-domain windowed module links to each other with described cyclic suffix generation module, is used for rear W/2 symbol of the front W/2 of this a frame training sequence symbol and this frame cyclic suffix carried out the time-domain windowed processing, and W is window length;
The time domain laminating module links to each other with described time-domain windowed module, after front W/2 symbol after being used for this frame training sequence processed through time-domain windowed and the processing of front frame cyclic suffix process time-domain windowed after W/2 symbol in time domain successively addition;
The subsequent treatment module links to each other with described time domain laminating module, is used for the signal after the time-domain windowed processing is carried out the post-treatment operations such as molding filtration, up-conversion and digital-to-analogue conversion.
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