CN101562588B - Wireless signal transmitting method and transmitter - Google Patents
Wireless signal transmitting method and transmitter Download PDFInfo
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- CN101562588B CN101562588B CN2008100933268A CN200810093326A CN101562588B CN 101562588 B CN101562588 B CN 101562588B CN 2008100933268 A CN2008100933268 A CN 2008100933268A CN 200810093326 A CN200810093326 A CN 200810093326A CN 101562588 B CN101562588 B CN 101562588B
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Abstract
The invention relates to a wireless signal transmitting method comprising the following steps: a plurality of orthogonal frequency division multitask (OFDM) cells are generated according to a data signal, and the OFDM cells are carried by a plurality of subcarriers; a scrambling typical sample which comprises a plurality of scrambling cells is generated, and the scrambling cells respectively correspond to the subcarriers in a frequency domain, wherein the scrambling cells which correspond to every two adjacent subcarriers have dependency; and the OFDM cells carried by the corresponding subcarriers are encoded by the scrambling cells.
Description
Technical field
The invention relates to a kind of wireless signal transmitting method and conveyer, and particularly relevant for a kind of frequency division collection and be beneficial to wireless signal transmitting method and the conveyer that passage is estimated when having.
Background technology
In wireless telecommunication system, conveyer is via such as physical channels such as air wireless signal being sent to receiver with form of electromagnetic wave.Since nonideal channelling effect, for example multi-path reflection (multipath reflection) or propagation decline (propagation fading) etc., and the wireless signal that causes receiver to receive may distortion.When the received multi-path signal of receiver has bigger delay extension (delay spread); Then the coherence bandwidth of this multi-path signal (coherent bandwidth) is understood the coherence bandwidth less than the single-pathway signal, and the channel response of multi-path signal (channel response) can produce frequency selective fading (frequency selective fading).OFDM (orthogonal frequency division multiplexing based on the multicarrier modulation; OFDM) modulation tech can overcome the channel response of this kind frequency selective fading, so on the application development of wireless telecommunications, become mainstream technology in recent years.
The OFDM modulation tech can be used in wireless telecommunication system and digital video and the news broadcasting system to carry out the spectral efficient transmission.The network construction of ofdm system can be divided into multi-frequency network (multiple frequency network, MFN) and Single Frequency Network (single frequency network, SFN).Wherein, Single Frequency Network is a radio network, and all conveyers transmit identical signal simultaneously on the same frequency passage.Single Frequency Network has multiple advantages, for example widely the network coverage, good frequency service efficiency, and the action user in network coverage, need not switch to another frequency band can be in moving reception signal etc.Use the ofdm system of Single Frequency Network to comprise: ground digital television broadcast (digital video broadcasting-terrestrial; DVB-T), handheld digital visual radio (digital video broadcasting-handheld; DVB-H), digital audio broadcasting (digital audio broadcasting; DAB), ground digital multimedia TV broad cast (digital multimedia broadcast-terrestrial; DMB-T) and the multimedia one directional service (media forward link only, Media-FLO) etc.
Ofdm system can overcome multi-path frequency selective fading effect; And channel coding (channel coding) and time interleaving (time interleaving) but function enhanced system usefulness; Even the signal that receives is because of producing mistake through the relatively poor part of channel response; Still can by channel response preferably partly utilize the error bit of channel-decoded correction of typist's errors.Staggered function of channel coding and time also can combine branch collection (diversity) technology, to make the channel response of the signal that receives have diversity further.Transmit to divide collection (diversity transmitting) or receive diversity (diversity receiving) to be applied to ofdm system usually so that bigger passage diversity to be provided, and allow good diversity gain to come enhanced system usefulness.
The Single Frequency Network that is applied to ofdm system is built to put in system has the network coverage and a large amount of conveyers widely.Yet when receiver was arranged in the covering border of two or more conveyers of Single Frequency Network, receiver can almost receive two or more identical signals simultaneously.Because the delay extension of these two or more signals is minimum, produce the coherence bandwidth of broad, make the variation of channel response slow, so produce flat fading passage (flat fading channel).If the phase place of these two or more signals or amplitude are different, may form destruction interference, cause lower channel response.What is worse, if receiver is near static, to such an extent as to be in the degree of depth of the time of low smooth channel response greater than time interleaving, channel response is very low for a long time, makes ofdm system usefulness possibly be in long period degradation (degrade).
Please with reference to Figure 1A and Figure 1B, Figure 1A shows the part sketch map of conventional wireless communication system, Figure 1B show the conventional wireless communication system the flat fading channel response one the example sketch map.In wireless telecommunication system 100, receiver 110 is positioned at the covering boundary of conveyer 108 of conveyer 102 and the area B of regional A.Conveyer 102 and conveyer 108 transmit respectively and contain a plurality of navigation cells (pilot symbol) p and a plurality of cell of data d (0), d (1) ..., the same wireless signal 112 and 118 of d (k).The channel response that wireless signal 112 passes regional A is h
a, the channel response that wireless signal 118 passes area B is h
bIf wireless signal 112 that conveyer 102 transmitted and the wireless signal 118 that conveyer 108 transmitted are s
00, the wireless signal 120 that receiver 110 received is s
01, then:
s
01＝s
00×(h
a+h
b)
Wherein, because wireless signal 112 and 118 corresponding multi-path delay extensions maybe be less, and have the different phase rotation, make destruction interference to produce.As channel response h
aBe similar to-h
bThe time, receiver 110 can produce the flat fading channel response (h of short arc
a+ h
b～0).Wherein, Except greatly reaching channel response, coherence bandwidth do not have the diversity; Because the value of the caused low reception signal channel response 122 of destruction interference maybe be less than the threshold value (threshold value) 124 of the signal detector in the receiver 110; Causing receiving signal can't correctly be judged, significantly reduces the receptivity of wireless telecommunication system.For in the systematic function that does not influence original Single Frequency Network; And need not change under the prerequisite of receiver design; The systematic function that the covering border of two conveyers of solution Single Frequency Network is produced reduces problem; How in transmitting signal, to do suitable diversity technique signal and handle, just become institute's desire and make great efforts one of problem that solves.
Utilize diversity technique to produce diversity gain (diversity gain), can prevent to produce lower and smooth channel response.Please with reference to Fig. 2, it shows that the conventional wireless communication system adopts the channel response sketch map of an example of diversity technique.In Fig. 2, be the method that adopts group's scrambler (group scrambling), wireless signal is transmitted on a plurality of subcarriers (subcarrier), and it is divided into a plurality of group of subcarriers.For example, the signal that first conveyer is transmitted is divided into group of subcarriers 211～212, and the signal that transmitted of second conveyer is divided into group of subcarriers 221～222, and each group of subcarriers comprises a plurality of cell of data and a plurality of navigation cell.
Each group of subcarriers utilizes different scrambler cell (scrambling symbol) to contained a plurality of cell of data and a plurality of navigation coding for information element respectively.Thus, at the covering boundary of two conveyers, receiver can produce the multifarious channel response 240 of tool when receiving wireless signal 230.The channel response 240 of each group of subcarriers has low correlation, therefore obtains frequency diversity gain, prevents that destructive signal from disturbing.Yet, because the channel response 240 after synthetic has discontinuity,, group's scrambling method estimates so possibly being unfavorable for the passage in the frequency domain, cause the passage estimation accuracy reduction of receiver and the increase that passage is estimated complexity.In addition, this group's scrambling method can't obtain the time diversity gain, because receiver near static caused slow decline passage, possibly still keep for a long time low passage response under these diversity situations, causing receiving signal can't correctly be judged.
Please with reference to Fig. 3, it shows that the conventional wireless communication system adopts another routine channel response sketch map of diversity technique.In Fig. 3, be the method that adopts a trellis formula grouping scrambler (grid group scrambling), wireless signal is transmitted on a plurality of subcarriers, and it is become a plurality of group of subcarriers according to time and frequency partition.For example; First conveyer is divided into group of subcarriers 311～312 in the signal that period C is transmitted; First conveyer is divided into group of subcarriers 313～314 in the signal that period D is transmitted; Second conveyer is divided into group of subcarriers 321～322 in the signal that period C is transmitted, and reaches second conveyer and is divided into group of subcarriers 323～324 in the signal that period D is transmitted, and each group of subcarriers comprises a plurality of cell of data and a plurality of navigation cell.
Each group of subcarriers utilizes different scrambler cells to contained a plurality of cell of data and a plurality of navigation coding for information element respectively.Thus, at the covering boundary of two conveyers, receiver can produce the multifarious channel response 340 of tool when receiving wireless signal 330.The channel response 340 of each group of subcarriers has low correlation, therefore obtains frequency diversity gain, prevents that destructive signal from disturbing.And this grid group scrambling method can obtain the time diversity gain, improves to receive signal because the approaching static long-time low passage response that causes of receiver.Yet the channel response 340 after synthesizing also has discontinuity, estimates so trellis formula grouping scrambling method still is unfavorable for passage, causes the passage of receiver to estimate that accuracy reduces and the increase of passage estimation complexity.
Summary of the invention
The object of the present invention is to provide a kind of wireless signal transmitting method and conveyer; Utilize the correlation scrambler in the conveyer; Make receiver have the time-frequency diversity gain in the covering border of two or more conveyers; And the channel response of the signal that receiver is received has continuity, can improve the passage of receiver and estimate accuracy.
According to a first aspect of the invention, propose a kind of wireless signal transmitting method, comprise the following steps.Produce a plurality of OFDMs (OFDM) cell according to a data signals, these a little OFDM cells are to be delivered by a plurality of subcarrier.Produce a scrambler type appearance, scrambler type appearance comprises a plurality of scrambler cells, and these a little scrambler cells correspond to the subcarrier in the frequency domain respectively.The scrambler cell that wherein corresponds to adjacent two number of sub-carrier has correlation.Utilize these a little scrambler cells to OFDM coding for information element that corresponding subcarrier delivered.
According to a second aspect of the invention, propose a kind of wireless signal conveyer, comprise an OFDM multiplexer and a correlation scrambler.The OFDM multiplexer is in order to produce a plurality of OFDM cells according to a data signals, and these a little OFDM cells are to be delivered by a plurality of subcarrier.The correlation scrambler is in order to producing a scrambler type appearance, and utilizes the included a plurality of scrambler cells of scrambler type appearance, to the OFDM coding for information element that corresponding this a little carrier wave delivered.Wherein, the scrambler cell that corresponds to adjacent two number of sub-carrier has correlation.
Specifically, wireless signal transmitting method provided by the invention comprises:
A. (those OFDM cells are delivered by a plurality of subcarriers (subcarrier) for orthogonal frequency division multiplexing, OFDM) cell to produce a plurality of OFDMs according to a data signals;
B. produce a scrambler type appearance (scrambling pattern), this scrambler type appearance comprises a plurality of scrambler cells, and those scrambler cells correspond to those subcarriers in the frequency domain respectively, and the scrambler cell that wherein corresponds to adjacent two number of sub-carrier has correlation; And
C. utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
Described wireless signal transmitting method, wherein, those scrambler cells all have EU Equivalent Unit gain (unit gain).
Described wireless signal transmitting method; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation (pilot) cell, and the difference on the frequency of adjacent two navigation cells is less than this scrambler symbol appearance pairing coherence bandwidth (coherent bandwidth) in frequency domain.
Described wireless signal transmitting method, wherein, this step b comprises:
B1. produce one group of random number, those random numbers are between 0～2 π;
Those random numbers are evenly distributed corresponding to those subcarriers; And
B3. equally distributed those random numbers are carried out linear interpolation and LPF, to produce this scrambler type appearance.
Described wireless signal transmitting method, wherein, this step b comprises:
B4. produce one group of time domain signal with delay extension (spread delay);
B5. this group time domain signal is carried out fourier transform (Fourier Transform) and obtains one group of frequency domain signal; And
B6. this group frequency domain signal is carried out convergent-divergent (Scale) to produce this scrambler type appearance.
Described wireless signal transmitting method wherein, is also finely tuned this group time domain signal according to a Doppler frequency (Doppler frequency) in this step b5.
Described wireless signal transmitting method; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell; The difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this wireless signal in frequency domain, and the time difference of adjacent two navigation cells is less than this scrambler type appearance pairing coherence time (coherent time) in time domain.
Described wireless signal transmitting method, wherein, this wireless signal is in a Single Frequency Network, to transmit.
Described wireless signal transmitting method wherein, carries out channel coding (channel coding) to produce those OFDM cells to this data signals.
Described wireless signal transmitting method wherein, carries out time interleaving (time interleaving) to produce those OFDM cells to this data signals.
Described wireless signal transmitting method, wherein, those scrambler cells that this scrambler type appearance is included are incomplete same scrambler cell.
Wireless signal conveyer provided by the invention comprises:
One OFDM multiplexer, in order to produce a plurality of OFDM cells according to a data signals, those OFDM cells are delivered by a plurality of subcarrier; And
One correlation scrambler in order to producing a scrambler type appearance, and utilizes the included a plurality of scrambler cells of this scrambler type appearance, to those OFDM coding for information element that corresponding those subcarriers delivered;
Wherein, the scrambler cell that corresponds to adjacent two number of sub-carrier has correlation.
Described wireless signal conveyer, wherein, those scrambler cells all have the EU Equivalent Unit gain.
Described wireless signal conveyer, wherein, those OFDM cells comprise plurality of data cell and a plurality of navigation cell, the difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this scrambler type appearance in frequency domain.
Described wireless signal conveyer, wherein, this correlation scrambler comprises:
One tandom number generator, in order to produce one group of random number, those random numbers are between 0～2 π;
One zero padding (zero-padding) unit, with so that those random numbers evenly distribute corresponding to those subcarriers;
One linear interpolation is in order to carry out linear interpolation to equally distributed those random numbers;
One low pass filter is in order to carry out LPF to those random numbers after the linear interpolation, to produce this scrambler type appearance; And
One multiplier is in order to utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
Described wireless signal conveyer, wherein, this correlation scrambler comprises:
One path generator (path generator) has the time domain signal that postpones extension in order to produce one group;
One fourier transform device is in order to carry out fourier transform and to obtain one group of frequency domain signal this group time domain signal;
One scaler is in order to carry out convergent-divergent to produce this scrambler type appearance to this group frequency domain signal; And
One multiplier is in order to utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
Described wireless signal conveyer, wherein, this correlation scrambler also comprises:
One Doppler frequency adjusting device is coupled between this path generator and this fourier transform device, in order to according to a Doppler frequency this group time domain signal is finely tuned.
Described wireless signal conveyer; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell; The difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this scrambler type appearance in frequency domain, and the time difference of adjacent two navigation cells is less than this scrambler type appearance pairing coherence time in time domain.
Described wireless signal conveyer, wherein, this wireless signal is in a Single Frequency Network, to transmit.
Described wireless signal conveyer also comprises:
One channel coder is in order to carry out channel coding to this data signals.
Described wireless signal conveyer also comprises:
One time interleaver is coupled between this channel coder and this OFDM device, in order to this data signals after the channel coding is carried out time interleaving.
Described wireless signal conveyer, wherein, those scrambler cells that this scrambler type appearance is included are incomplete same scrambler cell.
Effect of the present invention is:
Wireless signal transmitting method provided by the invention and conveyer; Under the prerequisite of the design of not changing receiver; In the wireless telecommunication system under Single Frequency Network, utilize the correlation scrambler in each conveyer, will have high correlation but incomplete same scrambler cell to OFDM coding for information element that corresponding subcarrier delivered; Make the channel response of the wireless signal that receiver received have diversity, and have less coherence bandwidth and short coherence time.So receiver has the time-frequency diversity gain in the covering border of two or more conveyers.In addition; Has high correlation owing to correspond to the scrambler cell of adjacent two number of sub-carrier; Thereby the passage that can improve receiver is estimated accuracy; Channel coding in the coupled system and time interleaving function can increase the diversity gain of receiver, promote the transmission performance and the coverage rate of wireless telecommunication system.
Description of drawings
Figure 1A shows the part sketch map of conventional wireless communication system
Figure 1B show the conventional wireless communication system the flat fading channel response one the example sketch map.
Fig. 2 shows that the conventional wireless communication system adopts the channel response sketch map of an example of diversity technique.
Fig. 3 shows that the conventional wireless communication system adopts another routine channel response sketch map of diversity technique.
Fig. 4 A shows the part sketch map according to the wireless telecommunication system of preferred embodiment of the present invention.
Fig. 4 B shows the sketch map according to an example of the channel response of the wireless telecommunication system of preferred embodiment of the present invention.
Fig. 5 shows the calcspar according to the wireless telecommunication system of preferred embodiment of the present invention.
Fig. 6 shows the calcspar according to an example of the correlation scrambler of preferred embodiment of the present invention.
Fig. 7 shows another the routine calcspar according to the correlation scrambler of preferred embodiment of the present invention.
Fig. 8 display radio communication system use various diversity techniques analog result one the example sketch map.
Fig. 9 display radio communication system is used another routine sketch map of the analog result of various diversity techniques.
Primary clustering symbol description in the accompanying drawing:
100,400,500: wireless telecommunication system
102,108,402,408: conveyer
110,410: receiver
112,118,120,230,330,412,418,420: wireless signal
122: the low signal channel response that receives
124: threshold value
211～212,221～222,311～314,321～324: group of subcarriers
240,340,440: channel response
510: conveyer
511: channel coder
512: the time interleaving device
513: modulator
The 514:OFDM multiplexer
515: the correlation scrambler
516: reverse fast fourier transformer
517,521: antenna
520: receiver
522: fast fourier transformer
523:OFDM separates multiplexer
524: the cell de-mapping device
525: the time deinterlacer
526: channel decoder
532: tandom number generator
534: the zero padding unit
536: linear interpolation
538: low pass filter
539,549: multiplier
542: the path generator
544: the Doppler frequency adjusting device
546: the fourier transform device
548: scaler
810、820、830、840、910、920、930、940：BLER
Embodiment
For letting the content of the present invention can be more obviously understandable, hereinafter is special lifts a preferred embodiment, and conjunction with figs. elaborates as follows.
The present invention proposes a kind of wireless signal transmitting method and conveyer; Utilize the correlation scrambler in the conveyer; To have high correlation but incomplete same a plurality of scrambler cells respectively to OFDM (orthogonal frequency division multiplexing that corresponding subcarrier delivered; OFDM) coding for information element; Make receiver have the time-frequency diversity gain, and the channel response of the received signal of receiver has continuity, can improve the passage of receiver and estimate accuracy in the covering border of two or more conveyers.
Please with reference to Fig. 4 A and Fig. 4 B, Fig. 4 A shows the part sketch map according to the wireless telecommunication system of preferred embodiment of the present invention, and Fig. 4 B shows the sketch map according to an example of the channel response of the wireless telecommunication system of preferred embodiment of the present invention.In Fig. 4 A, the network construction of wireless telecommunication system 400 is a Single Frequency Network.In wireless telecommunication system 400, receiver 410 is positioned at the covering boundary of conveyer 408 of conveyer 402 and the area B of regional A.Conveyer 402 and conveyer 408 transmit the same wireless signal 412 and 418 that contains a plurality of OFDM cells respectively, and these a little OFDM cells are to be delivered by a plurality of subcarriers (subcarrier).The channel response that wireless signal 412 passes regional A is h
a, the channel response that wireless signal 418 passes area B is h
bIf the wireless signal that conveyer 402 transmitted 412 is s
11And the wireless signal 418 that conveyer 408 transmitted is s
12(=s
11), the wireless signal 420 that receiver 410 received is s
13, then:
s
13＝s
11×h
a+s
12×h
b
In Fig. 4 B, a plurality of OFDM cells of wireless signal 412 and wireless signal 418 comprise navigation cell (pilot symbol) " 1 " and data cell d (0), d (1) ..., d (k).Before transmission; Conveyer 402 produces a scrambler type appearance (scrambling pattern); This scrambler type appearance comprises a plurality of scrambler cells (scrambling symbol); These a little scrambler cells all have EU Equivalent Unit gain (unit gain), and correspond to a plurality of subcarriers in the frequency domain (frequency domain) respectively.A plurality of scrambler cells in the scrambler type appearance that conveyer 402 is produced are incomplete same in fact, and the scrambler cell that wherein corresponds to adjacent two number of sub-carrier has high correlation.In addition, in frequency domain adjacent two the navigation cells difference on the frequency less than the pairing coherence bandwidth of scrambler type appearance (coherent bandwidth).That is this scrambler type appearance comes down to produce according to the design of the navigation cell in the wireless signal.
Similarly, conveyer 408 produces another scrambler type appearance, and this scrambler type appearance also comprises a plurality of scrambler cells.These a little scrambler cells are incomplete same in fact, and the scrambler cell that wherein corresponds to adjacent two number of sub-carrier has high correlation.Do not have correlation between the scrambler type appearance that conveyer 402 and conveyer 408 are produced.The signal of the scrambler cell coding in the two scrambler type appearance, (inverse fast Fourier transformer IFFT) (is not shown in Fig. 4 A and Fig. 4 B) can then to be forwarded to reverse fast fourier transformer in conveyer 402 and the conveyer 408.
The scrambler type sample that conveyer 402 produced of zone A is as being [a
1, a
2..., a
M], and the scrambler type sample that conveyer 408 produced of area B is as being [b
1, b
2..., b
M], wherein M is the sub-carrier number that each had in conveyer 402 and the conveyer 408.Wherein, a
1～a
MIncomplete same in fact Deng M scrambler cell, and have high correlation between adjacent scrambler cell.In like manner, b
1～b
MIncomplete same in fact Deng M scrambler cell, and have high correlation between adjacent scrambler cell.The channel response that in Single Frequency Network, is received from the wireless signal of conveyer 402 and conveyer 408 is:
h[1]＝h
a×a
1+h
b×b
1，
h[2]＝h
a×a
2+h
b×b
2，
h[3]＝h
a×a
3+h
b×b
3，
h[M]＝h
a×a
M+h
b×b
M。
For example, if the sub-carrier number M that each had in conveyer 402 and the conveyer 408 is 6, then the scrambler type appearance in the conveyer 402 of regional A can be [a
1, a
2..., a
6], and the scrambler type appearance in the conveyer 408 of area B can be [b
1, b
2..., b
6], wherein, scrambler cell a
1～a
6Has high correlation between incomplete same but adjacent scrambler cell, scrambler cell b
1～b
6Has high correlation between incomplete same but adjacent scrambler cell.The channel response that in Single Frequency Network, is received from the wireless signal of conveyer 402 and conveyer 408 can be:
h[1]＝h
a×a
1+h
b×b
1，
h[2]＝h
a×a
2+h
b×b
2，
h[3]＝h
a×a
3+h
b×b
3，
h[4]＝h
a×a
4+h
b×b
4，
h[5]＝h
a×a
5+h
b×b
5，
h[6]＝h
a×a
6+h
b×b
6。
Thus; The channel response 440 of wireless signal 420 can have diversity and continuity simultaneously, therefore not only can obtain frequency diversity gain, also can be beneficial to receiver 410 and carry out the passage estimation; Reduce the complexity that passage is estimated, the accuracy that makes passage estimate promotes.In addition, the wireless signal transmitting method that present embodiment disclosed can also make conveyer 402 and conveyer 408 produce different scrambler type appearance in the different periods.This different scrambler type appearance still makes the difference on the frequency of in frequency domain adjacent two navigation cells less than the coherence bandwidth of scrambler type appearance, and in time domain time difference of adjacent two navigation cells less than scrambler type appearance pairing coherence time.Thus, wireless signal 420 can obtain the time-frequency diversity gain simultaneously, and can carry out passage in time domain and estimate.
Please with reference to Fig. 5, it shows the calcspar according to the wireless telecommunication system of preferred embodiment of the present invention.Wireless telecommunication system 500 comprises a plurality of conveyers 510 and receiver 520.In wireless telecommunication system 500, on the network construction of Single Frequency Network, identical data signals is transmitted through a plurality of conveyers 510.Conveyer 510 comprises channel coder (channel encoder) 511, time interleaving device (time interleaver) 512, modulator 513, OFDM multiplexer 514, correlation scrambler (correlated scrambler) 515, IFFT516 and antenna 517.
The data signals that institute's tendency to develop is sent is carried out channel coding via channel coder 511, and the data signals after 512 pairs of channel codings of time interleaving device is carried out time interleaving then, carries out modulation by modulator 513 afterwards.Then OFDM multiplexer 514 produces a plurality of OFDM cells according to this.These a little OFDM cells are to be delivered by a plurality of subcarrier.Afterwards, a plurality of OFDM cells are transferred into correlation scrambler 515.Correlation scrambler 515 produces a scrambler type appearance, comprises a plurality of scrambler cells.The OFDM cell is forwarded to IFFT516 behind scrambler type appearance coding.In conveyer 510, channel coder 511 and time interleaving device 512 can be used for preventing continuous mistake, make receiver end assist the error recovery position according to through the correctly-decoded data position.
Please with reference to Fig. 6, it shows the calcspar according to an example of the correlation scrambler of preferred embodiment of the present invention.Correlation scrambler 515 comprises tandom number generator (random number generator) 532, zero padding (zero-padding) unit 534, linear interpolation (linear interpolator) 536, low pass filter 538 and multiplier 539.Tandom number generator 532 is in order to produce one group of random number, and these a little random numbers are between 0～2 π.Zero padding unit 534 usefulness so that this a little random numbers evenly distribute corresponding to a plurality of subcarriers of conveyer 510.Linear interpolation 536 is in order to carry out linear interpolation to equally distributed random number.Low pass filter 538 is the phase place of each scrambler cell in the scrambler type appearance in order to the random number after the linear interpolation is carried out LPF.Multiplier 539 utilizes this scrambler type appearance to OFDM coding for information element that corresponding subcarrier delivered.After, a plurality of OFDM cells after IFFT516 will encode convert the wireless signal of time domain into from frequency domain, and the wireless signal of time domain is then by antenna 517 transmission.
The scrambler type appearance that correlation scrambler 515 is produced comprises a plurality of scrambler cells, and these a little scrambler cells all have unit gain, and corresponds to a plurality of subcarriers in the frequency domain respectively.These a little scrambler cells are incomplete same in fact, and the scrambler cell that wherein corresponds to adjacent two number of sub-carrier has high correlation.In addition, in frequency domain adjacent two the navigation cells difference on the frequency less than the pairing coherence bandwidth of scrambler type appearance.That is this scrambler type appearance comes down to produce according to the design of the pilot tone cell in the wireless signal.Thus, the channel response of the wireless signal that receiver 520 is received can have diversity and continuity simultaneously, therefore not only can obtain frequency diversity gain, also can be beneficial to receiver and carry out passage and estimate.
In addition, correlation scrambler 515 also can have another execution mode.Please with reference to Fig. 7, it shows another the routine calcspar according to the correlation scrambler of preferred embodiment of the present invention.The correlation scrambler comprises path generator (path generator) 542, Doppler frequency adjusting device 544, fourier transform device 546, scaler 548 and multiplier 549.Path generator 542 has the time domain signal that postpones extension in order to produce one group.Doppler frequency adjusting device 544 is coupled between path generator 542 and the fourier transform device 546, in order to according to a Doppler frequency time domain signal that path generator 542 is produced is finely tuned.546 pairs of time domain signals of fourier transform device carry out fourier transform and obtain one group of frequency domain signal.548 pairs of frequency domain signals of scaler carry out convergent-divergent, make the frequency domain signal between 0～2 π, are the phase place of each scrambler cell in the scrambler type appearance.Multiplier 549 utilizes this scrambler type appearance to OFDM coding for information element that corresponding subcarrier delivered.
In the correlation scrambler 515 of Fig. 7; Because 544 pairs of time domain signals of Doppler frequency adjusting device are finely tuned; So the scrambler type appearance that correlation scrambler 515 is produced can have diversity in time domain; Make the channel response of the wireless signal that receiver 520 is received can have the time diversity gain, and on the time dimension time difference of adjacent two navigation cells can carry out passage in time dimension and estimate less than coherence time of scrambler type appearance.In addition, owing to fourier transform device 546 is the time domain signal to be carried out fourier transform obtain one group of frequency domain signal, so the scrambler type appearance that correlation scrambler 515 is produced be one group incomplete same and have a successional scrambler cell.Therefore, the channel response of the wireless signal that receiver 520 is received has frequency diversity gain, and is beneficial to receiver 520 and carries out passage and estimate.
Please with reference to Fig. 8, its display radio communication system is used the sketch map of an example of the analog result of various diversity techniques.In Fig. 8, be to utilize two single path channel modules to do explanation with little delay extension.Fig. 8 show block error rate in traditional OFDM technology of wireless signal after the demodulation (block error rate, BLER) 810, the BLER820 in group's scrambler technology, BLER830 and the BLER840 in correlation scrambler technology in trellis formula grouping scrambler technology.Can observe by Fig. 8 and to learn, when the BLER of target is 10
-2The time; The BLER840 of correlation scrambler technology is compared to the BLER810 of traditional OFDM technology, the BLER820 of group's scrambler technology and the BLER830 of grid group scrambler technology; At least improve the about 3.5dB of system effectiveness, promptly receiver can provide better system effectiveness under identical enforcement complexity.
Please with reference to Fig. 9, its display radio communication system is used another routine sketch map of the analog result of various diversity techniques.In Fig. 9, be to utilize typical case city, two six paths channel module (6-path typical urban channel model TU6) does explanation.Fig. 9 shows BLER910, BLER920 in group scrambler technology in, BLER930 and the BLER940 in correlation scrambler technology in trellis formula grouping scrambler technology in of wireless signal in traditional OFDM technology after the demodulation.Can observe by Fig. 9 and to learn, when the delay extension of channel response is big, uses correlation scrambler technology and can not produce the situation of wireless telecommunication system degradation of making, represent its performance robustness (robustness).
Wireless signal transmitting method that the above embodiment of the present invention disclosed and conveyer; Under the prerequisite of the design of not changing receiver; In the wireless telecommunication system under Single Frequency Network; Utilize the correlation scrambler in each conveyer; To have high correlation but incomplete same scrambler cell to the OFDM coding for information element that corresponding subcarrier delivered, make the channel response of the wireless signal that receiver received have diversity, and have less coherence bandwidth and short coherence time.So receiver has the time-frequency diversity gain in the covering border of two or more conveyers.In addition; Has high correlation owing to correspond to the scrambler cell of adjacent two number of sub-carrier; Thereby the passage that can improve receiver is estimated accuracy; Channel coding in the coupled system and time interleaving function can increase the diversity gain of receiver, promote the transmission performance and the coverage rate of wireless telecommunication system.
In sum, though the present invention discloses as above with a preferred embodiment, so it is not in order to limit the present invention.Have common knowledge the knowledgeable in the technical field under the present invention, do not breaking away from the spirit and scope of the present invention, when doing various changes and retouching.Therefore, protection scope of the present invention is as the criterion when the claim content that scope defines that look application.
Claims (22)
1. wireless signal transmitting method comprises:
A. produce a plurality of OFDM cells according to a data signals, those OFDM cells are delivered by a plurality of subcarrier;
B. produce a scrambler type appearance, this scrambler type appearance comprises a plurality of scrambler cells, and those scrambler cells correspond to those subcarriers in the frequency domain respectively, and the scrambler cell that wherein corresponds to adjacent two number of sub-carrier has correlation; And
C. utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
2. wireless signal transmitting method as claimed in claim 1, wherein, those scrambler cells all have the EU Equivalent Unit gain.
3. wireless signal transmitting method as claimed in claim 1; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell, and the difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this scrambler type appearance in frequency domain.
4. wireless signal transmitting method as claimed in claim 1, wherein, this step b comprises:
B1. produce one group of random number, those random numbers are between 0～2 π;
Those random numbers are evenly distributed corresponding to those subcarriers; And
B3. equally distributed those random numbers are carried out linear interpolation and LPF, to produce this scrambler type appearance.
5. wireless signal transmitting method as claimed in claim 1, wherein, this step b comprises:
B4. produce one group and have the time domain signal that postpones extension;
B5. this group time domain signal is carried out fourier transform and obtains one group of frequency domain signal; And
B6. this group frequency domain signal is carried out convergent-divergent to produce this scrambler type appearance.
6. wireless signal transmitting method as claimed in claim 5 wherein, is finely tuned this group time domain signal according to a Doppler frequency in this step b5.
7. wireless signal transmitting method as claimed in claim 6; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell; The difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this wireless signal in frequency domain, and the time difference of adjacent two navigation cells is less than this scrambler type appearance pairing coherence time in time domain.
8. wireless signal transmitting method as claimed in claim 1, wherein, this wireless signal is in a Single Frequency Network, to transmit.
9. wireless signal transmitting method as claimed in claim 1 wherein, carries out channel coding to produce those OFDM cells to this data signals.
10. wireless signal transmitting method as claimed in claim 1 wherein, carries out time interleaving to produce those OFDM cells to this data signals.
11. wireless signal transmitting method as claimed in claim 1, wherein, those scrambler cells that this scrambler type appearance is included are incomplete same scrambler cell.
12. a wireless signal conveyer comprises:
One OFDM multiplexer, in order to produce a plurality of OFDM cells according to a data signals, those OFDM cells are delivered by a plurality of subcarrier; And
One correlation scrambler in order to producing a scrambler type appearance, and utilizes the included a plurality of scrambler cells of this scrambler type appearance, to those OFDM coding for information element that corresponding those subcarriers delivered;
Wherein, the scrambler cell that corresponds to adjacent two number of sub-carrier has correlation.
13. wireless signal conveyer as claimed in claim 12, wherein, those scrambler cells all have the EU Equivalent Unit gain.
14. wireless signal conveyer as claimed in claim 12; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell, and the difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this scrambler type appearance in frequency domain.
15. wireless signal conveyer as claimed in claim 12, wherein, this correlation scrambler comprises:
One tandom number generator, in order to produce one group of random number, those random numbers are between 0～2 π;
One zero padding unit, with so that those random numbers evenly distribute corresponding to those subcarriers;
One linear interpolation is in order to carry out linear interpolation to equally distributed those random numbers;
One low pass filter is in order to carry out LPF to those random numbers after the linear interpolation, to produce this scrambler type appearance; And
One multiplier is in order to utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
16. wireless signal conveyer as claimed in claim 12, wherein, this correlation scrambler comprises:
One path generator has the time domain signal that postpones extension in order to produce one group;
One fourier transform device is in order to carry out fourier transform and to obtain one group of frequency domain signal this group time domain signal;
One scaler is in order to carry out convergent-divergent to produce this scrambler type appearance to this group frequency domain signal; And
One multiplier is in order to utilize those scrambler cells to those OFDM coding for information element that corresponding those subcarriers delivered.
17. wireless signal conveyer as claimed in claim 16, wherein, this correlation scrambler also comprises:
One Doppler frequency adjusting device is coupled between this path generator and this fourier transform device, in order to according to a Doppler frequency this group time domain signal is finely tuned.
18. wireless signal conveyer as claimed in claim 17; Wherein, Those OFDM cells comprise plurality of data cell and a plurality of navigation cell; The difference on the frequency of adjacent two navigation cells is less than the pairing coherence bandwidth of this scrambler type appearance in frequency domain, and the time difference of adjacent two navigation cells is less than this scrambler type appearance pairing coherence time in time domain.
19. wireless signal conveyer as claimed in claim 12, wherein, this wireless signal is in a Single Frequency Network, to transmit.
20. wireless signal conveyer as claimed in claim 12 comprises:
One channel coder is in order to carry out channel coding to this data signals.
21. wireless signal conveyer as claimed in claim 20 comprises:
One time interleaver is coupled between this channel coder and this OFDM device, in order to this data signals after the channel coding is carried out time interleaving.
22. wireless signal conveyer as claimed in claim 12, wherein, those scrambler cells that this scrambler type appearance is included are incomplete same scrambler cell.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1357179A (en) * | 1999-04-19 | 2002-07-03 | 艾利森电话股份有限公司 | System and method for implementing multiple carriers in cellular networks |
| CN101060363A (en) * | 2006-04-17 | 2007-10-24 | 华为技术有限公司 | Universal mobile communication system transmission method and its system |
| CN101141179A (en) * | 2006-09-08 | 2008-03-12 | 华为技术有限公司 | Method and device for implementing information transfer in wireless communication system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1357179A (en) * | 1999-04-19 | 2002-07-03 | 艾利森电话股份有限公司 | System and method for implementing multiple carriers in cellular networks |
| CN101060363A (en) * | 2006-04-17 | 2007-10-24 | 华为技术有限公司 | Universal mobile communication system transmission method and its system |
| CN101141179A (en) * | 2006-09-08 | 2008-03-12 | 华为技术有限公司 | Method and device for implementing information transfer in wireless communication system |
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