CN101356758B - OFDM reception device and OFDM receiver using the same - Google Patents
OFDM reception device and OFDM receiver using the same Download PDFInfo
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- CN101356758B CN101356758B CN200780001384.7A CN200780001384A CN101356758B CN 101356758 B CN101356758 B CN 101356758B CN 200780001384 A CN200780001384 A CN 200780001384A CN 101356758 B CN101356758 B CN 101356758B
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Abstract
An OFDM reception device includes: a reception unit for receiving a signal; a first transmission path estimation unit for estimating a transmission path distortion by using a signal of a first time interval outputted from the reception unit; a second transmission path estimation unit for estimating a transmission path distortion by using a signal of a second time interval shorter than the first time interval outputted from the reception unit; a selection unit for selecting one of the signal from the first transmission path estimation unit and the signal from the second transmission path estimation unit according to a control signal from a control unit and outputting the signal; and a correction unit for correcting a reception signal outputted from the reception unit according to the transmission path estimation signal from the selection unit. The control unit decides the control signal to the selection unit according to the reception state of the reception unit.
Description
Technical field
The present invention relates to receive OFDM (below, write a Chinese character in simplified form " OFDM ") signal and estimate that the characteristic of channel is with OFDM receiving system that improves receptivity and the OFDM receiving equipment that uses it.
Background technology
In recent years, begun to carry out adopting the digital broadcasting of OFDM modulation system.
But the portable terminal receiving system is to use small size antenna to come the system of received signal.Therefore, compare the position received signal that described small size antenna is must be on distance ground lower with employed family expenses large-scale antenna in the fixedly receiving system of family expenses.And, while because moving, the user watches broadcasting, so the reception environment of portable terminal receiving system variation significantly.Especially, in the abominable reception environment of the channel distortion of the frequency selectivity that is caused by multipath and the decline that is caused by mobile reception etc., the signal waveform in the time of must restoring transmission according to the signal waveform that receives is to reproduce broadcast program.
Known before in so abominable reception environment, the channel correction technique is effective.
So-called channel correction technique is meant to estimate the wave distortion that channel produces, and the distortion of removing received signal, the technology of revising thus.In digital broadcasting, on frequency axis direction and time shaft direction, certain known between transmitter side and receiver side pilot signal is arranged with the arranged spaced of stipulating.Therefore, receiving system can be calculated amplitude variation and the amount of phase rotation according to the difference of pilot signal that is received and the inner pilot signal that produces of receiver, thereby learns wave distortion and the time change that produces in the channel.Therefore, carry out interpolation processing, estimate the wave distortion and the time change of pilot signal data-signal position in addition thus, and carry out correcting process, thereby can improve anti-multipath and anti-fading property according to this information.
In addition, as the prior art documentation ﹠ info relevant with the application's invention, known have a for example non-patent literature 1.
In the channel estimating of carrying out using pilot signal, receiving feature significantly changes according to being used to estimate the pilot positions of handling.For example, when using the pilot signal that on time-axis direction (symbol direction), separates the 1st interval and dispose to carry out channel estimation process, and separate than the 1st the short at interval the 2nd at interval and the pilot signal of configuration when carrying out channel estimation process when using, received signal to the tracing ability of time fluctuation and to frequency selectivity aberration estimation precision difference.Therefore, the anti-multipath of OFDM receiving system and anti-fading property difference.
Before, use any channel estimation methods to carry out interpolation processing, therefore be difficult to take into account anti-multipath and anti-fading property.
Non-patent literature 1: well head goods respects/gloomy good auxilliary/once field rolling/god open country one was flat for wood, on the ground デ ジ タ Le is broadcasted trusted device To お け Ru Xie De Fill Inter mode The and is sent with い Den that infer on the road, the Da Hui Talk of Electricity feelings Reported Communications Society drills the Theory collected works, VOL.2005 ソ サ イ エ テ イ 1, the 531 ペ one ジ (channel estimating of use diagonal interpolation (diagonal interpolation) mode in the received terrestrial digital broadcasting receiver, electronic information communication association conference speech collection of thesis, 2005 volumes, the 1st phase, the 531st page)
Summary of the invention
OFDM receiving system of the present invention has: acceptance division, and it receives ofdm signal; First channel estimation unit, it uses the very first time signal at interval that has of acceptance division output from then on to estimate channel distortion; Second channel estimation portion, it uses from the signal with second time interval of lacking at interval than the described very first time of acceptance division output estimates channel distortion; Control part, its accepting state according to acceptance division is exported control signal.The OFDM receiving system also has: selection portion, and it is according to control signal, and selection and output are from the channel estimating signal of first channel estimation unit with from any signal in the channel estimating signal of second channel estimation portion; And, correction portion, it is according to the channel estimating signal from selection portion, to revising from the received signal of acceptance division output.
According to such structure, in the OFDM receiving system of the present invention, first channel estimation unit is used the channel estimation methods of anti-multipath excellence, and second channel estimation portion uses the channel estimation methods of anti-fading property excellence.Like this, according to the accepting state of acceptance division and selectively use any estimated result to carry out correcting process, can take into account anti-fading property and anti-multipath thus.
And OFDM receiving system of the present invention comprises at least: first acceptance division that receives ofdm signal; Be connected to the first channel correction portion of this first acceptance division; Receive second acceptance division of ofdm signal; Be connected to the second channel correction portion of this second acceptance division; And the diversity portion that is connected to the first channel correction portion and second channel correction portion.And the first channel correction portion is used from the very first time signal at interval that has of first acceptance division output and is estimated channel distortion, with this received signal of exporting from first acceptance division is revised.The second channel correction portion is used from the signal with second time interval of lacking at interval than the very first time of second acceptance division output and is estimated channel distortion, with this received signal of exporting from second acceptance division is revised.
According to such structure, in the OFDM receiving system of the present invention, the first channel correction portion uses the channel estimation methods of anti-fading property excellence to revise, and the second channel correction portion uses the channel estimation methods of anti-multipath excellence to revise.Like this, each output signal divided assemble, thereby can take into account anti-fading property and anti-multipath.
Description of drawings
Fig. 1 is the block diagram of the OFDM receiving equipment of embodiment of the present invention 1.
Fig. 2 is the key diagram of the time shaft interpolation of embodiment of the present invention 1.
Fig. 3 is the key diagram of the frequency axis interpolation of embodiment of the present invention 1.
Fig. 4 is the key diagram of the diagonal interpolation of embodiment of the present invention 1.
Fig. 5 is the key diagram of the frequency axis interpolation of embodiment of the present invention 1.
Fig. 6 is the block diagram of the OFDM receiving system of embodiment of the present invention 2.
Fig. 7 is the block diagram of the OFDM receiving system of embodiment of the present invention 3.
Fig. 8 is the block diagram of another routine OFDM receiving system of embodiment of the present invention 3.
Fig. 9 is the block diagram of the OFDM receiving equipment of embodiment of the present invention 4.
Figure 10 is the block diagram of another routine OFDM receiving system of embodiment of the present invention 4.
Figure 11 is the block diagram of the OFDM receiving system of embodiment of the present invention 5.
Figure 12 is the block diagram of another routine OFDM receiving system of embodiment of the present invention 5.
Figure 13 is the block diagram of the OFDM receiving system of embodiment of the present invention 6.
Figure 14 is the block diagram of another routine OFDM receiving system of embodiment of the present invention 6.
The explanation of Reference numeral
2,302 acceptance divisions
3,207 first channel estimation unit
4,209 second channel estimation portions
5,211 control parts
6 selection portions
7,208,210 correction portions
8 antennas
9 tuning portions
10 AD converter sections
11 orthogonal detection portions
12 fast fourier transform portions
13 incoming level test sections
14 fading frequency estimation portions
15 signal quality measured portions
19、21、31、35、219、221、231、233、241、254
The OFDM receiving system
34,259 N channel estimation unit
61,261 signal processing parts
63,263 display parts
71,271,273 OFDM receiving equipments
202 first acceptance divisions
204 second acceptance divisions
203 first channel correction portions
205 second channel correction portions
206,226 diversity portions
208,210,260 correction portions
212 enable circuits
213 signal selecting parts
214 error correction portions
215 error rate measurement portions
251 N acceptance divisions
253 N channel correction portions
255 CN compare measurement section
Embodiment
Below, use accompanying drawing that embodiments of the present invention are described.
(execution mode 1)
Below, use Fig. 1 to Fig. 4 that embodiments of the present invention 1 are described.Fig. 1 is the block diagram of the OFDM receiving equipment 71 of embodiment of the present invention 1.As shown in Figure 1, OFDM receiving system 19 has: the acceptance division 2 that receives ofdm signal; First channel estimation unit 3, it utilizes the very first time signal at interval of acceptance division 2 outputs from then on to estimate channel distortion; And second channel estimation portion 4, its utilization is estimated channel distortion from the signal in second time interval that the ratio very first time of acceptance division 2 outputs lacks at interval.And, OFDM receiving system 19 also has selection portion 6, this selection portion 6 is according to selecting and output from the control signal of control part 5, from the channel estimating signal of first channel estimation unit 3 and from any the channel estimating signal in the channel estimating signal of second channel estimation portion 4.OFDM receiving system 19 also has correction portion 7, and this correction portion 7 is according to the channel estimating signal from selection portion 6, to revising from the received signal of acceptance division 2 outputs.
And acceptance division 2 has: antenna 8, and it receives the ofdm signal that sends with high-frequency signal; And tuning 9, it converts the high-frequency signal that this antenna 8 is received to intermediate-freuqncy signal.And acceptance division 2 also has: AD converter section 10, and it will be that intermediate-freuqncy signal converts digital signal to from the analog signal of tuning 9 output; And orthogonal detection portion 11, its digital signal to AD converter section 10 outputs is from then on carried out orthogonal detection and is handled.Acceptance division 2 also has fast fourier transform portion 12, and 12 pairs of signals from 11 outputs of orthogonal detection portion of this fast fourier transform portion carry out digital Fourier transform processing, with this time shaft conversion of signals are become the frequency axis signal.
Then, use accompanying drawing to illustrate that first channel estimation unit 3 and second channel estimation portion 4 use the pilot signal of ofdm signal to estimate the method for channel distortion.Fig. 2 has represented the signal configures of ofdm signal.In addition, the configuration of the pilot signal of Fig. 2 is an illustration, and the present invention is not subjected to the restriction of this configuration.On the position shown in the Shuan Quan, dispose pilot signal, and on the position shown in the Bai Quan, dispose data-signal.Because pilot signal is a signal known between transmitter side and receiver side, so OFDM receiving system 19 can use the pilot signal that is received to carry out channel estimating, so that data-signal is carried out correcting process.The processing method that some kinds of channel estimating are arranged herein.
The 1st method is at first carried out the time shaft interpolation.Now use Fig. 2 to come the time shaft interpolation is described.Shown in the dotted arrow among Fig. 2, use the pilot signal in same carrier wave in the time-axis direction arrangement, the data-signal between pilot signal is carried out interpolation.In Fig. 3, use the circle that has added oblique line to represent to have carried out in the above described manner the signal of time shaft interpolation.On the frequency axis direction, shown in the dotted arrow among Fig. 3, in prosign (symbol), per 3 carrier waves obtain the signal of pilot signal and elapsed time axle interpolation.Then, the 1st method is carried out the frequency axis interpolation.That is, use the signal of these pilot signals and elapsed time axle interpolation, at the enterprising row interpolation of frequency axis direction (with the direction shown in the dotted arrow).Its result, the remaining data shown in the white circle obtains interpolation.Therefore, can obtain the channel estimation value (not shown) of all data-signals.
Shown in the dotted arrow among Fig. 4, the 2nd method is at first at the enterprising row interpolation of diagonal.Among Fig. 5, use the circle that has added oblique line to represent to have carried out in the above described manner the signal of diagonal interpolation.Shown in the dotted arrow among Fig. 5, in prosign, obtain the signal of pilot signal and process diagonal interpolation.Then, the 2nd method is carried out the frequency axis interpolation.That is, use these pilot signals and, at the enterprising row interpolation of frequency axis direction (direction of representing with dotted arrow) through the signal of diagonal interpolation.Its result, the remaining data shown in the white circle obtains interpolation.Therefore, can obtain the channel estimation value (not shown) of all data-signals.
Herein, the 1st method and the 2nd method are compared.The 1st method use on time-axis direction with the very first time at interval, the pilot signal that disposes on promptly per 4 symbols is carried out interpolation, and the 2nd method was used on diagonal with second time interval, the pilot signal that disposes on promptly per 3 symbols is carried out interpolation.Therefore, the 2nd method is better for the tracing ability of time fluctuation, and bigger for the improvement of anti-fading property.
On the other hand, the 1st method is used pilot signal or the time shaft interpolated signal that disposes at per 3 carrier waves on the frequency axis direction, and the 2nd method is used pilot signal or diagonal interpolated signal in per 4 carrier waves configuration.Therefore, the 1st method is better aspect the frequency selectivity distortion, and bigger for the improvement of anti-multipath.
Like this, first channel estimation unit 3 is exported the result who uses described the 1st methods and estimate, and second channel estimation portion 4 exports the result who uses described the 2nd methods and estimate.Then, control part 5 is according to the accepting state of acceptance division 2, and when making the received signal quality variation because the frequency selectivity distortion is big, output is used to select the control signal of first channel estimation unit 3.And when making the received signal quality variation because time fluctuation is big, described control part 5 outputs are used to select the control signal of second channel estimation portion 4.Then, any channel estimating signal is selected and exported to selection portion 6 according to the control signal from control part 5.Then, correction portion 7 is used from the channel estimating signal of selection portion 6 inputs, comes thus, to select best channel estimation methods according to accepting state, thereby can take into account anti-multipath and anti-fading property revising from the received signal of acceptance division 2 outputs.
The simple control method of control part 5, the frequency of the with good grounds high-frequency signal that receives is come the method for selective channel method of estimation, below this control method is described.But the maximum translational speed of the OFDM receiving system 19 of received signal is closely related, promptly closely related with fading frequency with the speed of the time fluctuation of received signal.If establishing receive frequency is fc, but the maximum fading frequency of establishing received signal is fdmax, and establishing the light velocity is c, but the maximum movement speed v max of the OFDM receiving system 19 of received signal can represent with (formula 1) so.
Formula 1:
That is the maximum movement speed v max relation of being inversely proportional to of receive frequency fc and OFDM receiving system 19.Herein, utilize the receivable maximum fading frequency of aforementioned the 1st method to be fdmax1 if establish, if utilize the receivable maximum fading frequency of the 2nd method for fdmax2 (＞fdmax1), the 1st method so, can come received signal by maximum setting fc_t1 with receive frequency, setting fc_t1 represents with (formula 2).
Formula 2:
And the 2nd method can be come received signal by maximum setting fc_t2 with receive frequency, and setting fc_t2 represents with (formula 3).
Formula 3:
Suc as formula 2, shown in the formula 3, the maximum movement speed v max by maximum fading frequency fdmax1, fdmax2 and OFDM receiving system 19 obtains fc_t1 and fc_t2 respectively.Herein, the relation of fc_t1＜fc_t2 is set up.As mentioned above, the 1st method is better aspect anti-multipath.Therefore, when receive frequency during less than setting fc_t1, control part 5 is controlled, to select utilizing the 1st method to carry out first channel estimation unit 3 of channel estimating, and when receive frequency be that setting fc_t1 is when above, control part 5 is controlled, to select utilizing the 2nd method to carry out the second channel estimation portion 4 of channel estimating.Thus, required mobile receptivity can be in the receive frequency range of broad, guaranteed, and when receive frequency is low, anti-multipath can be guaranteed.For example, in the purposes of the highest translational speed of knowing OFDM receiving system 19 in advance of vehicle-mounted reception etc., when receive frequency fc hour, can improve anti-multipath by selecting first channel estimation unit 3.
In addition, also can change the channel estimation methods of first channel estimation unit 3 and second channel estimation portion 4 according to receive frequency fc.That is, control with the mode in second time interval at interval, can further take into account anti-fading property and anti-multipath thus to switch the described very first time according to receive frequency.
In addition, proposed the method for multiple channel estimating, for some system, just studied and do not using pilot signal to estimate to increase the method for transmission amount of information.In such system, OFDM method of reseptance of the present invention also is effective.
(execution mode 2)
Below, use Fig. 6 that embodiments of the present invention 2 are described.Fig. 6 is the block diagram of the OFDM receiving system 21 of embodiment of the present invention 2.To the identical mark of the structure mark identical and omit its explanation, difference is described in detail with execution mode 1.In Fig. 6, OFDM receiving system 21 also has except the structure that Fig. 1 is arranged: incoming level test section 13, and it is connected between the AD converter section 10 and orthogonal detection portion 11 of acceptance division 2, and detects the signal level of received signal; And fading frequency estimation portion 14, it is connected on the incoming level test section 13, the fading frequency of estimating received signal, and this fading frequency outputed in the control part 5.
In this structure, when from the fading frequency of fading frequency estimation portion 14 input during less than setting, control part 5 is used to select control signal from the input signal of first channel estimation unit 3 to selection portion 6 outputs.And, when from the fading frequency of fading frequency estimation portion 14 input when setting is above, control part 5 is used to select control signal from the input signal of second channel estimation portion 4 to selection portion 6 outputs.In addition, though for example when normal the reception, estimate that fading frequency can reach about 100Hz, the setting of fading frequency can be set to come about 80Hz control part 5 is controlled.As implement described in the mode 1, in case determine the maximum movement speed v max of OFDM receiving system 19, can reach (formula 3) by (formula 2) so and decide: in first channel estimation unit 3 or the second channel estimation portion 4 which control part 5 should select according to the receive frequency of acceptance division 2.By setting by this way, can select any in first channel estimation unit 3 and the second channel estimation portion 4 more accurately, thereby can take into account anti-fading property and anti-multipath.In addition, anti-fading property can change because of the performance improvement of acceptance division or channel estimating mode, but because the invention is characterized in two channel estimation unit having used characteristic different, so the present invention is not limited to this occurrence.
Herein, can by analyze incoming level through the time change, in fading frequency estimation portion 14, carry out fading frequency and estimate.For example, the incoming level value in past can be saved in the memory, and estimate fading frequency by the distribution of calculating the incoming level value.
(execution mode 3)
Below, use Fig. 7 that embodiments of the present invention 3 are described.Fig. 7 is the block diagram of the OFDM receiving system 31 of embodiment of the present invention 3.To the identical mark of the structure mark identical and omit its explanation, difference is described in detail with execution mode 1.In Fig. 7, OFDM receiving system 31 also has signal quality measured 15 except the structure that Fig. 1 is arranged, and this signal quality measured 15 is connected to correction portion 7, and exports the signal quality of received signals to control part 5.
In this structure, when the signal quality ratio of exporting from signal quality measured 15 was stipulated value difference, the control signal that control part 5 outputs are selected from the signal of another channel estimation unit selection portion 6 can be taken into account anti-multipath and anti-fading property thus.
Can use carrier level with the noise level of received signal ratio (hereinafter referred to as CN than) as the signal quality in signal quality measured 15.Promptly, under the situation of having selected first channel estimation unit 3, for example corrupt to 10dB when following when the CN ratio, exist translational speed to become big and cause fading frequency to become big possibility, therefore, control part 5 is controlled to select the second channel estimation portion 4 of anti-fading property excellence.On the other hand, under the situation of having selected second channel estimation portion 4, for example corrupt to 10dB when following when the CN ratio, exist multipath to become big and cause the frequency selectivity distortion to become big possibility, therefore, control part 5 is controlled to select first channel estimation unit 3 of anti-multipath excellence.By above control, can select the channel estimation methods that is more suitable for according to accepting state, thereby can take into account anti-multipath and anti-fading property.
In addition, as the signal quality of the ofdm signal of execution mode 3, the setting of CN ratio is made as 10dB, but can comes appropriate change according to the modulation parameter of broadcast system.And, also can use the signal level of received signal or error rate as signal quality.In addition, error rate for example can be used bit error rate or Packet Error Ratio.And the setting as signal quality of the signal level of received signal for example also can be made as-80dBm.And the setting as signal quality of the bit error rate of received signal for example also can be made as 2 * 10
-4
In addition, when control part 5 has switched channel estimation unit, the time that the state of the control signal by will exporting to selection portion 6 is maintained fixed, can further improve characteristic.Promptly, because it is to utilize the pilot signal of specific time interval to carry out interpolation processing that the estimation in the channel estimation unit is handled, so when control part 5 when fully selection portion 6 being carried out switching controls greater than the cycle in this time interval, can ignore the deterioration of following the correcting process of switching and producing.Therefore, can be made as for example 500 milliseconds the set time.When 5 pairs of channel estimation unit of control part were carried out switching, during about 500 milliseconds after switching in, be subjected to following the processing delay of switching and producing and measure the influence that postpones, signal quality measured reliability can temporarily reduce.Therefore, be maintained fixed the time, can be subjected to above-mentioned the influence thus by the state that will be input to the control signal in the selection portion 6.Like this, when control part 5 carries out switching controls with the cycle that can't ignore with respect to this time interval, in correction portion 7, follow the quality of reception deterioration of switching.On the other hand, by setting switching cycle less, can improve tracing ability for the variation of reception environment.Therefore, in case carried out switching controls, control part 5 was not controlled selection portion 6 in the set time, and the state of retentive control signal can be set switching cycle less thus, and can suppress to follow the quality of reception deterioration of switching.But according to the difference of the processing method of broadcast system or demodulation section etc., therefore the set time difference can suitably be selected.
And, in the above description, used first channel estimation unit 3 and second channel estimation portion 4 the two channel estimation unit that are used as having nothing in common with each other, but as shown in Figure 8, also can have the different channel estimation unit more than three or three.Fig. 8 is the block diagram of another routine OFDM receiving system 35 of embodiment of the present invention 3.As shown in the figure, OFDM receiving system 35 possesses N channel estimation unit, has omitted the 3rd later channel estimation unit among the figure, but has represented N N channel estimation unit 34.Selection portion 6, comprise first channel estimation unit 3 and second channel estimation portion 4 the two, also utilize any the estimated result in N the channel estimation unit that has nothing in common with each other to carry out correcting process.Therefore, can realize simultaneously and the corresponding a plurality of characteristics more than three of the characteristic of channel estimation unit.
For example, the situation with three channel estimation unit is narrated.If this kind situation comprises the 3rd channel estimation unit (not shown), this 3rd channel estimation unit is to carry out channel estimating than first channel estimation unit 3, second channel estimation portion in 4 the 3rd shorter time intervals.For example, utilize the estimated result of the 3rd channel estimation unit in the 3rd time interval to carry out correcting process herein, when fading frequency during more than or equal to 150Hz.And, when fading frequency during, utilize the estimated result of the second channel estimation portion 4 in second time interval to carry out correcting process more than or equal to 100Hz and less than 150Hz.In addition, when fading frequency during, utilize the estimated result of the very first time first channel estimation unit 3 at interval to carry out correcting process less than 100Hz.By such mode, can select in three channel estimation unit according to signal quality and switch, thereby can carry out accurate more control.
(execution mode 4)
Below, use Fig. 9 to Figure 10 that embodiments of the present invention 4 are described.Fig. 9 is the block diagram of the OFDM receiving equipment 271 of embodiment of the present invention 4.As shown in Figure 9, OFDM receiving system 219 has: first acceptance division 202 that receives ofdm signal; And be connected to the first channel correction portion 203 on first acceptance division 202.And OFDM receiving system 219 also has: second acceptance division 204 that receives ofdm signal; And be connected to second channel correction portion 205 on this second acceptance division 204.In addition, first acceptance division 202 possesses identical structure and function with second acceptance division 204.And OFDM receiving system 219 also has the diversity portion 206 that is connected on the first channel correction portion 203 and the second channel correction portion 205.And first acceptance division 202 and second acceptance division 204 possess and the identical structure of acceptance division shown in Figure 12 in the execution mode 1, and have the fast fourier transform portion (not shown) that carries out Fourier transform to received signal respectively.
In addition, the OFDM receiving equipment 271 that is carrying OFDM receiving system 219 has: the signal processing part 261 that is connected to the outlet side of diversity portion 206; And the display part 263 that is connected to the outlet side of signal processing part 261.And the first channel correction portion 203 is made of first channel estimation unit 207 and correction portion 208, and this first channel estimation unit 207 is according to estimating channel status from the received signal of first acceptance division, 202 outputs; This correction portion 208 is revised to received signal according to the estimated result of first channel estimation unit 207.Second channel correction portion 205 is made of second channel estimation portion 209 and correction portion 210, and this second channel estimation portion 209 is according to estimating channel status from the received signal of second acceptance division, 204 outputs; Described correction portion 210 is revised to received signal according to the estimated result of second channel estimation portion 209.In addition, first channel estimation unit 207 possess with execution mode 1 in identical structure and the function of first channel estimation unit 3.Equally, second channel estimation portion 209 possesses structure and the function identical with the second channel estimation portion 4 in the execution mode 1.Therefore omit the detailed description that is equal to part.
In such structure, the first channel correction portion 203 is used from the very first time received signal at interval of first acceptance division, 202 outputs and is carried out channel estimating.Then, according to this estimated result, correction portion 208 outputs to revised result in the diversity portion 206.Second channel correction portion 205 use from 204 outputs of second acceptance division, than the very first time at interval the received signal in the second short time interval carry out channel estimating.Then, according to this estimated result, correction portion 210 outputs to revised result in the diversity portion 206.In addition, diversity portion 206 synthesizes the input signal from the first channel correction portion 203 and second channel correction portion 205 according to each signal quality that the signal quality calculator (not shown) by diversity portion 206 inside calculates.Synthesize, for example can determine synthetic ratio with the ratio (C/N) of noise level according to the carrier level of the first channel correction portion 203 and second channel correction portion 205 output signal separately.Thus, not only can utilize the first channel correction portion 203 to realize anti-multipath but also can utilize second channel correction portion 205 to realize anti-fading property.But synthetic method is not limited to the method, also can use other method.
For the concrete example of situation, also with in the execution mode 1 use the mode that Fig. 2 to Fig. 5 narrated similarly to carry out the estimation of channel distortion, and carry out the correction of received signal with pilot signal.
Promptly, the first channel correction portion 203 is used the 1st method described in the execution mode 1, and use following pilot signal to estimate channel distortion, this pilot signal is included in from the received signal of first acceptance division, 202 outputs, and disposes with the 1st mark space (per 4 symbols).Then, to revising from the received signal of first acceptance division, 202 outputs.In addition, second channel correction portion 205 is used the 2nd method described in the execution mode 1, and use following pilot signal to estimate channel distortion, this pilot signal is included in from the received signal of second acceptance division, 204 outputs, and is to dispose with the 2nd mark space (per 3 symbols) shorter than the 1st mark space.Then, to revising from the received signal of second acceptance division, 204 outputs.
Therefore, use the 1st method to estimate by first channel estimation unit 207,203 outputs of the first channel correction portion are carried out revised received signal according to this estimated result.And, use the 2nd method to estimate by second channel estimation portion 209,205 outputs of second channel correction portion are carried out revised received signal according to this estimated result.Then, 206 pairs of signals from described first channel correction portion 203 and second channel correction portion 205 of diversity portion synthesize, thereby can take into account the anti-multipath that obtained by the frequency selectivity distorted characteristic in the 1st method and follow characteristic and the anti-fading property that obtains by the time in the 2nd method.
And, except structure shown in Figure 9, the body that is connected in series of N acceptance division and channel correction portion can also be set as shown in figure 10.Figure 10 is the block diagram of another routine OFDM receiving system 221 of embodiment of the present invention 4.As shown in the figure, OFDM receiving system 221 possesses the body that is connected in series of N acceptance division and channel correction portion, has omitted the 3rd the later body that is connected in series among the figure, but has represented N be connected in series body i.e. N acceptance division 251 and N channel correction portion 253.And N channel correction portion 253 is made of N channel estimation unit 259 and correction portion 260, and this N channel estimation unit 259 is according to estimating channel status from the received signal of N acceptance division 251 outputs; This correction portion 260 is revised to received signal according to the estimated result of N channel estimation unit 259.And each channel correction portion is revised by the channel estimation methods that use has nothing in common with each other, and then by diversity portion 226 each output is synthesized, and can obtain the effect of further characteristic being improved thus.
In addition, proposed the method for multiple channel estimating, for some system, just studied and do not using pilot signal to estimate to increase the method for transmission amount of information.In such system, OFDM method of reseptance of the present invention also is effective.
(execution mode 5)
Below, use Figure 11 that embodiments of the present invention 5 are described.Figure 11 is the block diagram of the OFDM receiving system 231 of embodiment of the present invention 5.To the identical symbol of the structure mark identical and omit its explanation, difference is described in detail with execution mode 4.In Figure 11, OFDM receiving system 231 also has except the structure that comprises Fig. 9: control part 211; And enable circuits 212, it makes second acceptance division 204 begin the control of moving or stopping to move according to the control signal from control part 211 inputs.And, OFDM receiving system 231 also has signal selecting part 213, this signal selecting part 213 is connected respectively on first acceptance division 202 and second acceptance division 204, and the control signal according to from control part 211 inputs outputs to the input signal of any in first acceptance division 202 and second acceptance division 204 in the second channel correction portion 205.In addition, OFDM receiving system 231 also has: be connected to the error correction portion 214 in the diversity portion 206; And be connected error rate measurement portion 215 between error correction portion 214 and the control part 211.And shown in the dotted line among Figure 11, error rate measurement portion 215 also can be connected in the diversity portion 206 and measure the preceding CN ratio of error correction.
In this structure, when the measured error rate of error rate measurement portion 215 during less than setting, the control signal that control part 211 stops to move to enable circuits 212 outputs, and to the control signal of signal selecting part 213 output selections from the input signal of first acceptance division 202.And, when error rate during, the control signal that control part 211 begins to move to enable circuits 212 outputs, and select control signal from the input signal of second acceptance division 204 to signal selecting part 213 outputs more than or equal to setting.In addition, error rate can be used for example bit error rate or Packet Error Ratio.And the setting of the bit error rate of received signal for example also can be made as 2 * 10
-4
By this control, when good and error rate was less than setting when reception environment, enable circuits 212 made second acceptance division 204 stop action, to realize low power consumption.And, the input signal that signal selecting part 213 is selected from first acceptance division 202.Thus, for the signal that first acceptance division 202 is received, not only revise, and utilize different channel estimation methods to revise by second channel correction portion 205 by the first channel correction portion 203.And, utilize 206 pairs of output signals of diversity portion to synthesize from these first channel correction portions 203 and second channel correction portion 205, can take into account low power consumption and anti-fading property and anti-multipath thus.
On the other hand, when abominable and error rate is more than or equal to setting when reception environment, make second acceptance division 204 begin action, and the input signal selected from second acceptance division 204 of signal selecting part 213, receiving sensitivity can be improved thus.That is, utilize diversity portion 206 that the signal that the antenna (not shown) that is had separately by first acceptance division 202 and second acceptance division 204 is received is synthesized, when the noise of these two antenna systems was uncorrelated, receiving sensitivity was improved.For example, if the signal that each antenna received uncorrelated (coefficient correlation is 0), receiving sensitivity will improve 3dB so.
By carrying out above control, the OFDM receiving system 231 of execution mode 5 is when reception environment is good, reduce power consumption by making second acceptance division 204 stop action, and use the first channel correction portion 203 and second channel correction portion 205 these two correction portions to revise, therefore also can suppress the receiving feature variation.On the other hand, when reception environment was abominable, this OFDM receiving system 231 can be guaranteed the receiving sensitivity characteristic by making second acceptance division 204 begin action.
And control part 211 not only can use error rate to control, and also can use the index of expression signal qualitys such as CN ratio to control.Figure 12 is the block diagram of another routine OFDM receiving system 233 of embodiment of the present invention 5.As shown in figure 12, OFDM receiving system 233 possesses CN than measurement section 255, to replace error rate measurement portion 215 shown in Figure 11.CN can be according to measuring the CN ratio from the signal of diversity portion 206 outputs than measurement section 255.Like this, recently control, can shorten signal quality and detect the required time as the index of expression signal quality by using CN.In addition, the setting of the CN of received signal ratio can be made as for example 10dB.
(execution mode 6)
Below, use Figure 13 that embodiments of the present invention 6 are described.Figure 13 is the block diagram of the OFDM receiving equipment 273 of embodiment of the present invention 6.To the identical mark of the structure mark identical and omit its explanation, difference is described in detail with execution mode 4.In Figure 13, OFDM receiving system 241 has: the acceptance division 302 that receives ofdm signal; Be connected to the first channel correction portion 203 on the acceptance division 302; Be connected to the second channel correction portion 205 on the acceptance division 302; And the diversity portion 206 that is connected with the first channel correction portion 203 and second channel correction portion 205.In addition, acceptance division 302 possess with execution mode 4 in identical structure and the function of first acceptance division 202.And the OFDM receiving equipment 273 that is carrying OFDM receiving system 241 possesses: the signal processing part 261 that is connected to the outlet side of diversity portion 206; And the display part 263 that is connected to the outlet side of signal processing part 261.
In this structure, the first channel correction portion 203 uses following pilot signal to estimate channel distortion, and this pilot signal is included in from the received signal of acceptance division 302 outputs, and disposes with the 1st mark space.Then, to revising from the received signal of acceptance division 302 outputs.Second channel correction portion 205 uses following pilot signal to estimate channel distortion, and this pilot signal is included in from the received signal of acceptance division 302 outputs, and is to dispose with the 2nd mark space shorter than the 1st mark space.Then, to revising from the received signal of acceptance division 302 outputs.
The first channel correction portion 203 uses aforesaid the 1st method to estimate channel distortion, with this received signal of exporting from acceptance division 302 is revised, second channel correction portion 205 uses aforesaid the 2nd method to estimate channel distortion, with this received signal of exporting from acceptance division 302 is revised.Then, 206 pairs of signals from the first channel correction portion 203 and 205 inputs of second channel correction portion of diversity portion synthesize, and can take into account anti-multipath that is obtained by the 1st method and the anti-fading property that is obtained by the 2nd method with this.
In addition, compare, can omit second acceptance division 204 in the OFDM receiving system 241 shown in Figure 13 in execution mode 6, therefore can further realize miniaturization, low power consumption with the OFDM receiving system 219 shown in Figure 9 in the execution mode 4.
And, in the above description, the channel estimation unit of having used the first channel correction portion 203 and 205 the two conducts of second channel correction portion to have nothing in common with each other, but as shown in figure 14, also can have the different channel correction portion more than three.Figure 14 is the block diagram of another routine OFDM receiving system 254 of embodiment of the present invention 6.As shown in the figure, OFDM receiving system 254 possesses N channel correction portion, has omitted the 3rd later channel correction portion among the figure, but expression has N N channel correction portion 253.Like this, acceptance division 302 and the channel correction portion more than three that is connected on the acceptance division 302 are set, and use the channel estimation methods that has nothing in common with each other to revise by each channel correction portion.Then, utilize diversity portion 206 that each output is synthesized, thereby can obtain the effect further characteristic improved.
The industrial utilization possibility
OFDM receiving system of the present invention has a plurality of channel estimating apparatus, and these a plurality of channel estimating apparatus have not identical characteristic separately, can take into account a plurality of characteristics such as anti fading performance and anti-multipath thus. OFDM receiving system of the present invention is for need to be in various environment particularly useful while moving the OFDM receiving equipments such as the portable terminal that receives or car-mounted terminal.
Claims (19)
1. OFDM receiving system comprises:
Acceptance division, it receives ofdm signal;
First channel estimation unit, it uses from the very first time signal at interval that has of described acceptance division output estimates channel distortion;
Second channel estimation portion, it uses from the signal with second time interval of lacking at interval than the described very first time of described acceptance division output estimates channel distortion;
Control part, its accepting state according to described acceptance division is exported control signal;
Selection portion, it is according to described control signal, select and output from the channel estimating signal of described first channel estimation unit with from any signal in the channel estimating signal of described second channel estimation portion;
Correction portion, it is according to the described channel estimating signal from described selection portion, to revising from the received signal of described acceptance division output; And
Signal quality measured portion, it measures the signal quality of the signal that described correction portion exports,
When the described signal quality from described signal quality measured output compared the regulation value difference, described control part output made the control signal of described selection portion selection from the signal of another channel estimation unit.
2. OFDM receiving system according to claim 1, wherein,
Described control part is set the frequency of the described ofdm signal that described acceptance division receives, and
When the frequency of the described ofdm signal that sets during less than setting, described control part is selected described control signal from the described channel estimating signal of described first channel estimation unit to described selection portion output,
When the frequency of the described ofdm signal that sets during more than or equal to setting, described control part is selected described control signal from the described channel estimating signal of described second channel estimation portion to described selection portion output.
3. OFDM receiving system according to claim 1 also comprises:
The incoming level test section, it detects the incoming level of the described ofdm signal that described acceptance division receives; And
Fading frequency estimation portion, it estimates the fading frequency of described ofdm signal, and outputs in the described control part according to the described incoming level of the described ofdm signal of exporting from described incoming level test section,
When from the described fading frequency of described fading frequency estimation portion output during less than setting, described control part is selected described control signal from the described channel estimating signal of described first channel estimation unit to described selection portion output,
When from the described fading frequency of described fading frequency estimation portion output during more than or equal to setting, described control part is selected described control signal from the described channel estimating signal of described second channel estimation portion to described selection portion output.
4. OFDM receiving system according to claim 1, wherein,
Described signal quality measured measured described signal quality is the signal level of the signal exported of described correction portion.
5. OFDM receiving system according to claim 1, wherein,
Described signal quality measured measured described signal quality is the ratio of carrier level with the noise level of the signal exported of described correction portion.
6. OFDM receiving system according to claim 1, wherein,
Described signal quality measured measured described signal quality is the error rate of the signal exported of described correction portion.
7. OFDM receiving system according to claim 1, wherein,
When described control part change outputs to the described control signal of described selection portion, the state that outputs to the described control signal of described selection portion is maintained fixed the time.
8. OFDM receiving system according to claim 1, wherein,
Have the channel estimation unit that is connected to described acceptance division more than three, described selection portion is according to selecting from any signal in the signal of described channel estimation unit from the described control signal of described control part.
9. OFDM receiving equipment comprises:
Acceptance division, it receives ofdm signal;
First channel estimation unit, it uses from the very first time signal at interval that has of described acceptance division output estimates channel distortion;
Second channel estimation portion, it uses from the signal with second time interval of lacking at interval than the described very first time of described acceptance division output estimates channel distortion;
Control part, its accepting state according to described acceptance division is exported control signal;
Selection portion, it is according to described control signal, select and output from the channel estimating signal of described first channel estimation unit with from any signal in the channel estimating signal of described second channel estimation portion;
Correction portion, it is according to the described channel estimating signal from described selection portion, to revising from the received signal of described acceptance division output;
Signal quality measured portion, it measures the signal quality of the signal that described correction portion exports;
Be connected to the signal processing part of the outlet side of described correction portion; And
Be connected to the display part of the outlet side of described signal processing part,
When the described signal quality from described signal quality measured output compared the regulation value difference, described control part output made the control signal of described selection portion selection from the signal of another channel estimation unit.
10. OFDM receiving system comprises:
Receive first acceptance division of ofdm signal;
Be connected to the first channel correction portion of described first acceptance division;
Receive second acceptance division of described ofdm signal;
Be connected to the second channel correction portion of described second acceptance division; And
Be connected to the diversity portion of described first channel correction portion and described second channel correction portion,
The described first channel correction portion is used from the very first time signal at interval that has of described first acceptance division output and is estimated channel distortion, with this received signal of exporting from described first acceptance division revised,
Described second channel correction portion is used from the signal with second time interval of lacking at interval than the described very first time of described second acceptance division output and is estimated channel distortion, with this received signal of exporting from described second acceptance division is revised.
11. OFDM receiving system according to claim 10, wherein,
Described ofdm signal has pilot signal,
The described first channel correction portion is used to be included in from the described received signal of described first acceptance division output and with the pilot signal of the 1st mark space configuration and is estimated channel distortion, with this described received signal of exporting from described first acceptance division revised,
Described second channel correction portion, use is included in from the described received signal of described second acceptance division output and with the pilot signal of the 2nd mark space configuration shorter than described the 1st mark space estimates channel distortion, with this described received signal of exporting from described second acceptance division is revised.
12. OFDM receiving system according to claim 10, wherein,
The body that is connected in series that is connected in series and is formed by described acceptance division and described channel correction portion more than three is set, the described channel correction portion of each described body that is connected in series uses the signal in the time interval that has nothing in common with each other to estimate channel distortion, to revising from the described received signal of described acceptance division output.
13., also comprise according to claim 10 or 11 described OFDM receiving systems:
Control part;
Enable circuits, it begins action or stops action according to control described second acceptance division from the control signal of described control part input;
Signal selecting part, it is connected respectively to described first acceptance division and described second acceptance division, and, according to described control signal from described control part input, to output in the described second channel correction portion from the described received signal of described first acceptance division with from any the described received signal in the described received signal of described second acceptance division;
Error correction portion, it is connected to described diversity portion; And
Error rate measurement portion, it is connected between described error correction portion and the described control part and measures error rate,
When described error rate during, the described control signal that described control part stops to move to described enable circuits output, and select described control signal from the described received signal of described first acceptance division to described signal selecting part output less than setting,
When described error rate during more than or equal to described setting, the described control signal that described control part begins to move to described enable circuits output, and to the described control signal of described signal selecting part output selection from the described received signal of described second acceptance division.
14., also comprise according to claim 10 or 11 described OFDM receiving systems:
Control part;
Enable circuits, it begins action or stops action according to control described second acceptance division from the control signal of described control part input;
Signal selecting part, it is connected respectively to described first acceptance division and described second acceptance division, and, according to described control signal from described control part input, to output in the described second channel correction portion from the described received signal of described first acceptance division with from the described received signal of described second acceptance division any; And
CN is than measurement section, and it is connected to described diversity portion and measures the CN ratio,
When described CN compares greater than setting, the described control signal that described control part stops to move to described enable circuits output, and to the described control signal of described signal selecting part output selection from the described received signal of described first acceptance division,
When described CN compares smaller or equal to described setting, the described control signal that described control part begins to move to described enable circuits output, and to the described control signal of described signal selecting part output selection from the described received signal of described second acceptance division.
15. an OFDM receiving system comprises:
Receive the acceptance division of ofdm signal;
Be connected to the first channel correction portion of described acceptance division;
Be connected to the second channel correction portion of described acceptance division; And
Be connected to the diversity portion of described first channel correction portion and described second channel correction portion,
The described first channel correction portion is used from the very first time signal at interval that has of described acceptance division output and is estimated channel distortion, with this received signal of exporting from described acceptance division revised,
Described second channel correction portion is used from the signal with second time interval of lacking at interval than the described very first time of described acceptance division output and is estimated channel distortion, to revising from the received signal of described acceptance division output.
16. OFDM receiving system according to claim 15, wherein,
Described ofdm signal has pilot signal,
The described first channel correction portion, its use are included in from the signal of described acceptance division output and with the pilot signal of the 1st mark space configuration estimates channel distortion, with this received signal of exporting from described acceptance division is revised,
Described second channel correction portion, its use is included in from the described received signal of described acceptance division output and with the pilot signal of the 2nd mark space configuration shorter than described the 1st mark space estimates channel distortion, with this described received signal of exporting from described acceptance division is revised.
17. OFDM receiving system according to claim 15, wherein,
Described channel correction portion more than three is set,
Each described channel correction portion is used from the signal with the time interval that has nothing in common with each other of described acceptance division output and is estimated channel distortion, with this described received signal of exporting from described acceptance division is revised.
18. an OFDM receiving equipment comprises:
Receive first acceptance division of ofdm signal;
Be connected to the first channel correction portion of described first acceptance division;
Receive second acceptance division of described ofdm signal;
Be connected to the second channel correction portion of described second acceptance division;
Be connected to the diversity portion of described first channel correction portion and described second channel correction portion;
Be connected to the signal processing part of the outlet side of described diversity portion; And
Be connected to the display part of the outlet side of described signal processing part,
The described first channel correction portion is used from the very first time signal at interval that has of described first acceptance division output and is estimated channel distortion, with this received signal of exporting from described first acceptance division revised,
Described second channel correction portion is used from the signal with second time interval of lacking at interval than the described very first time of described second acceptance division output and is estimated channel distortion, to revising from the received signal of described second acceptance division output.
19. an OFDM receiving equipment comprises:
Receive the acceptance division of ofdm signal;
Be connected to the first channel correction portion of described acceptance division;
Be connected to the second channel correction portion of described acceptance division;
Be connected to the diversity portion of described first channel correction portion and described second channel correction portion;
Be connected to the signal processing part of the outlet side of described diversity portion; And
Be connected to the display part of the outlet side of described signal processing part,
The described first channel correction portion is used from the very first time signal at interval that has of described acceptance division output and is estimated channel distortion, with this received signal of exporting from described acceptance division revised,
Described second channel correction portion is used from the signal with second time interval of lacking at interval than the described very first time of described acceptance division output and is estimated channel distortion, to revising from the described received signal of described acceptance division output.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006158187A JP2007329626A (en) | 2006-06-07 | 2006-06-07 | Ofdm receiving device and ofdm receiving equipment using the same |
| JP158187/2006 | 2006-06-07 | ||
| JP240992/2006 | 2006-09-06 | ||
| JP2006240992A JP4905003B2 (en) | 2006-09-06 | 2006-09-06 | OFDM receiver and OFDM receiver using the same |
| PCT/JP2007/060967 WO2007142091A1 (en) | 2006-06-07 | 2007-05-30 | Ofdm reception device and ofdm receiver using the same |
Publications (2)
| Publication Number | Publication Date |
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| CN101356758A CN101356758A (en) | 2009-01-28 |
| CN101356758B true CN101356758B (en) | 2011-08-03 |
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| CN200780001384.7A Expired - Fee Related CN101356758B (en) | 2006-06-07 | 2007-05-30 | OFDM reception device and OFDM receiver using the same |
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| CN (1) | CN101356758B (en) |
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| US20140018025A1 (en) | 2011-03-30 | 2014-01-16 | Ntt Docomo, Inc. | Receiving device, receiving method, and computer program |
| JP5881453B2 (en) * | 2012-02-14 | 2016-03-09 | 三菱電機株式会社 | Equalizer, receiver, and equalization method |
| US8995543B2 (en) * | 2013-06-28 | 2015-03-31 | Intel Mobile Communications GmbH | Method and device for channel estimation with colliding interference cancellation |
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|---|---|---|---|---|
| CN1543103A (en) * | 2003-05-02 | 2004-11-03 | ���ǵ�����ʽ���� | Apparatus and method for performing channel estimation in an orthogonal frequency division multiplexing (ofdm) system using multiple antennas |
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| JP2004282613A (en) * | 2003-03-18 | 2004-10-07 | Sony Corp | Equalization apparatus and receiving apparatus with the same |
| US7433433B2 (en) * | 2003-11-13 | 2008-10-07 | Telefonaktiebolaget L M Ericsson (Publ) | Channel estimation by adaptive interpolation |
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| CN1543103A (en) * | 2003-05-02 | 2004-11-03 | ���ǵ�����ʽ���� | Apparatus and method for performing channel estimation in an orthogonal frequency division multiplexing (ofdm) system using multiple antennas |
Non-Patent Citations (2)
| Title |
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| JP特开2004-282613A 2004.10.07 |
| 董江波，王刚，李道本.线性插值信道估计中导频间隔的最优化设计.《北京邮电大学学报》.2004,第27卷增刊卷207-211. * |
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| CN101356758A (en) | 2009-01-28 |
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