CN101018218A - An interference restraint method of the adjacent channels and signal receiving end - Google Patents
An interference restraint method of the adjacent channels and signal receiving end Download PDFInfo
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- CN101018218A CN101018218A CNA2006101652328A CN200610165232A CN101018218A CN 101018218 A CN101018218 A CN 101018218A CN A2006101652328 A CNA2006101652328 A CN A2006101652328A CN 200610165232 A CN200610165232 A CN 200610165232A CN 101018218 A CN101018218 A CN 101018218A
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Abstract
The disclosed near-channel interference rejection method comprises: when receiving signal, the receiving end filters signal with an analog filter; a first sampling module samples the filter signal and filters the sampled signal with digital filter module; and a second sampling module samples signal and transforms the signal sampling rate into system signal rate. This invention combines both analog and digital filtering, rejects interference efficiently, and reduces system complexity and power consumption.
Description
Technical field
The present invention relates to wireless communication field, relate in particular to a kind of method that suppresses adjacent-channel interference, and signal receiving end.
Background technology
The media that mobile communication and broadcasting utilize radio wave to propagate as information, making rational planning for of frequency resource is very important.Current, multiple mobile communication and broadcast system are also deposited, and frequency resource is very nervous, and radio regulatory organization is carried out unified the division and distribution to radio frequency.For improving the frequency resource utilization ratio; adjacent channel protection between the mobile system neutralized system is more and more littler at interval; the influence of disturbing between adjacent channel is serious all the more; particularly for adopting OFDM (Orthogonal Frequency Division Multiplexing; OFDM) the digital mobile multi-media broadcasting system of technology; its amplitude spectrum is smooth and have little transition band in system bandwidth, as shown in Figure 1.For the correct data that receive, receiving terminal need effectively suppress adjacent-channel interference.
The method that the conventional digital mobile multimedia broadcast receiving terminal suppresses adjacent-channel interference increases high performance analog filter as shown in Figure 2 after AFE (analog front end), for example Surface Acoustic Wave Filter or ceramic filter are with the outer energy of check strap.These filters have good squareness factor, can effectively suppress the interference of adjacent channel.But the high performance analog filter has the big and high shortcoming of power consumption of volume, is not suitable for adopting in integrated circuit (IC)-components.
Summary of the invention
The invention provides a kind of adjacent-channel interference inhibition method, in order to solve in the prior art because of using analog filter to carry out the problem that adjacent-channel interference suppresses that the receiving terminal volume that causes is big, power consumption is high, design is complicated, is not suitable for the integrated device realization.
Based on identical technical conceive, the present invention provides a kind of signal receiving end in addition.
Adjacent-channel interference inhibition method provided by the invention, after receiving terminal receives signal, carry out following steps:
The analog filter of AFE (analog front end) inside carries out filtering to the received signal, obtains filtering signal;
Described filtering signal is carried out over-sampling, and the sampled signal that obtains is carried out digital filtering;
The filtered signal of numeral is sampled, signal sampling rate is transformed to the character rate of system.
Described over-sampling frequency is at least transmitting terminal baseband signal bandwidth and described analog filter cut-off frequency sum.
When carrying out data filtering, the character rate that the transition band bandwidth of employing is no more than described system deducts 2 times baseband signal bandwidth.
Receiving terminal provided by the invention comprises that there is the AFE (analog front end) of analog filter inside, also comprises first sampling module, digital filtering module and second sampling module;
Described analog filter, the signal that is used for described AFE (analog front end) is received carries out filtering;
Described first sampling module is used for the filtered signal of described analog filter is carried out over-sampling;
Described digital filtering module is used for the sampled signal of described first sampling module is carried out digital filtering;
Described second sampling module is used for the filtered signal of described digital filtering module is sampled, and the filtered signals sampling rate of described digital filtering module is transformed to the character rate of system.
The over-sampling frequency that described first sampling module is adopted is at least transmitting terminal signal baseband bandwidth and described analog filter cut-off frequency sum.
The character rate that the transition band bandwidth of described digital filtering module is no more than system deducts 2 times baseband signal bandwidth.
Beneficial effect of the present invention is as follows:
(1) the present invention is by being used in combination analog filtering and digital filtering technique at signal receiving end, interference to adjacent channel suppresses, analog filter by digital filtering module and AFE (analog front end) inside, adopt the hybrid mode of analog filtering and digital filtering to replace high performance analog filter of the prior art, thereby when guaranteeing interference suppressioning effect, reduced implementation complexity, so that adopt integrated circuit (IC)-components to realize, and then save power consumption.
(2) the present invention adopts the over-sampling frequency that the analog filtering signal is sampled, and has provided minimum over-sampling frequency, can reduce over-sampling device and Design of Digital Filter requirement when reducing the signal frequency aliasing.
(3) the present invention has provided span to the transition band bandwidth of digital filtering module, thereby guarantees that digital filtering module effectively suppresses the interference of adjacent channel, and reduces the computing cost of digital filtering module.
Description of drawings
Fig. 1 is the amplitude spectrum of OFDM symbol;
Fig. 2 is an adjacent-channel interference inhibition method schematic diagram of the prior art;
Fig. 3 is the digital mobile multimedia broadcast signal receiving terminal structural representation of the embodiment of the invention;
Fig. 4 is a schematic diagram of selecting the over-sampling frequency in the embodiment of the invention;
Fig. 5 is the frequency range schematic diagram of AFE (analog front end) in the embodiment of the invention;
Fig. 6 is the frequency response schematic diagram of the low-performance filters of AFE (analog front end) in the embodiment of the invention;
Fig. 7 is the frequency response schematic diagram of digital filter in the embodiment of the invention.
Embodiment
The embodiment of the invention proposes a kind of inhibition method of the adjacent-channel interference at the digital mobile multi-medium broadcasting receiving terminal, this method combines analog filtering and digital filtering technique, with the interference of effective inhibition adjacent channel, and make the receiving terminal that adopts this method be suitable for the integrated circuit (IC)-components realization.
Referring to Fig. 3, be the digital mobile multimedia broadcast signal receiving terminal structural representation of the embodiment of the invention.This receiving terminal comprises AFE (analog front end), over-sampling module, digital filter and down sample module.Analog signal is input to AFE (analog front end), passes through above-mentioned module successively, from down sample module output digital signal.There is the analog filter of low performance AFE (analog front end) inside.
Below in conjunction with receiving terminal shown in Figure 3, the adjacent-channel interference process of inhibition is described.
The low performance analog filter of AFE (analog front end) inside carries out preliminary filtering to the analog signal that is input to AFE (analog front end), with the outer energy of inhibition zone.But because the filter bandwidht in the AFE (analog front end) is greater than baseband signal bandwidth (the baseband signal bandwidth highest frequency that is defined as baseband signal and zero frequency is poor herein), so still there is the interference of adjacent channel in filtered signal.
Signal after AFE (analog front end) will be handled outputs to the over-sampling module.
The over-sampling module is carried out over-sampling to the signal of AFE (analog front end) output, and analog signal is transformed to digital signal.The over-sampling module adopts the over-sampling frequency to sample, in order to avoid produce frequency alias.For fear of frequency alias, generally, sample frequency is at least Nyquist sample rate (twice of baseband signal bandwidth).Be referred to as over-sampling with the method for sampling much larger than the Nyquist sample rate.Because stopband attenuation is not enough near the low-performance filters cut-off frequency in the AFE (analog front end), adopt over-sampling rate can alleviate the aliasing effect of bringing thus.But the over-sampling frequency is too high also can the follow-up Design of Digital Filter requirement of corresponding increase.
The principle that present embodiment is selected over-sampling rate is as shown in Figure 4: the baseband bandwidth of establishing input signal is B (2B is the pass band width of signal), the bandwidth of low-performance filters (for example 3dB decay position) is Bp, the cut-off frequency of low-performance filters (for example 50dB decay position) is Fd, then Zui Xiao over-sampling frequency is Fss=B+Fd, so just can guarantee frequency not aliasing advance effective bandwidth.
The over-sampling module outputs to digital filter with sampled signal.
Digital filter carries out filtering to oversampled signals, with the outer energy of further inhibition zone.Digital filter adopts low pass filter, and filtering bandwidth is the baseband bandwidth of input signal, and the scope of transition band bandwidth B t is 0～and (Fs-2 * B), wherein, Fs is the sample rate (sample rate of down sample module equates with the character rate of system) of down sample module.In order to reduce the computing cost of digital filtering, it is Bt=Fs-2 * B that present embodiment is selected the bandwidth of transition band.
Digital filter output filtering signal is to down sample module.
Down sample module adopts the frequency that equates with the character rate of system to sample.Because aforementioned over-sampling, through the signal rate of the digital filtering module output character rate much larger than system, so down sample module extracts the sample in the digital signal of input, the signals sampling rate is transformed to the character rate of system.
Be described with the process of inhibition of an application example below adjacent-channel interference.This exemplary application is in the mobile digital multi-media broadcast field, and the traffic frequencies bandwidth is 8MHz.
The mobile digital multi-media broadcast per second transmits 1 frame signal, and every frame is divided into 40 time slots, and the length of each time slot is 25ms, and the data of each slot transmission comprise 1 beacon and 53 OFDM modulated data blocks, and the sample frequency of transmitting terminal time-domain signal is 10MHz.
The frequency range of AFE (analog front end) is-12MHz～12MHz, can hold three traffic frequencies, and the frequency range of AFE (analog front end) as shown in Figure 5.Channel0 among the figure is the signal that needs, and Channel1 and Channel2 are the interference signal of adjacent channel.The homophase and the quadrature two paths of signals of AFE (analog front end) output zero intermediate frequency.The bandwidth of the low-performance filters of AFE (analog front end) inside (3dB) is 7MHz (desirable bandwidth is 4MHz), and cut-off frequency is 11MHz (decay 50dB).The homophase of AFE (analog front end) output and orthogonal signalling are behind this filter filtering, the interference signal that still has adjacent channel, Fig. 6 shows the frequency response of the low performance analog filter of AFE (analog front end) inside, as can be seen, the signal of frequency more than 7MHz is just by effective attenuation, but not enough to the signal attenuation between the 7MHz at 4MHz, interference signal still exists.
AFE (analog front end) outputs to the over-sampling module with filtered signal.
The over-sampling rate that the over-sampling module adopts is Fss=B+Fd, wherein, B is baseband signal bandwidth 4MHz, Fd is the cut-off frequency 11MHz (decay 50dB) of the analog filter of AFE (analog front end) inside, therefore adopt the over-sampling frequency of 15MHz that homophase and quadrature two paths of signals are sampled, can guarantee not occurrence frequency aliasing.
Over-sampling module output sampled signal is to digital filter.
Digital filter is a low pass filter, with the outer energy of further inhibition zone.The transition band bandwidth of digital filter is Fs-2 * B, and wherein, Fs is the sample rate 10MHz (character rate of system equates) of down sample module, and B is baseband bandwidth 4MHz, therefore adopts the transition band bandwidth of 2MHz.The frequency response of low pass filter as shown in Figure 7, the bandwidth of its 3dB correspondence is 4MHz, transition band bandwidth 2MHz, cut-off frequency is 6MHz (decay 60dB), as can be seen, therefore the signal of frequency more than 4MHz, adopted this low pass filter can effectively suppress the interference signal of adjacent channel by effective attenuation.
The signal of digital filter after with low-pass filtering outputs to down sample module.
Down sample module adopts the frequency 10MHz sampling low-pass filter signal that equates with the character rate of system, signal sampling rate is transformed to the character rate of system.
In sum, the embodiment of the invention adopts analog filtering and digital filtering technique, interference to adjacent channel suppresses, replace high performance analog filter of the prior art, thereby when guaranteeing interference suppressioning effect, reduced implementation complexity, so that adopt integrated circuit (IC)-components to realize, and then save power consumption.The embodiment of the invention adopts the over-sampling frequency that the analog filtering signal is sampled, and can guarantee not aliasing of signal frequency.The embodiment of the invention has also provided span to the transition band bandwidth of digital filter, thereby guarantees that digital filter effectively suppresses the interference of adjacent channel, and reduces the computing cost of digital filter.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.
Claims (6)
1, a kind of adjacent-channel interference inhibition method is characterized in that, after receiving terminal receives signal, carries out following steps:
The analog filter of AFE (analog front end) inside carries out filtering to the received signal, obtains filtering signal;
Described filtering signal is carried out over-sampling, and the sampled signal that obtains is carried out digital filtering;
The filtered signal of numeral is sampled, signal sampling rate is transformed to the character rate of system.
2, the method for claim 1 is characterized in that, described over-sampling frequency is at least transmitting terminal baseband signal bandwidth and described analog filter cut-off frequency sum.
3, the method for claim 1 is characterized in that, when carrying out data filtering, the character rate that the transition band bandwidth of employing is no more than system deducts 2 times baseband signal bandwidth.
4, a kind of signal receiving end comprises that there is the AFE (analog front end) of analog filter inside, it is characterized in that, also comprises first sampling module, digital filtering module and second sampling module;
Described analog filter, the signal that is used for described AFE (analog front end) is received carries out filtering;
Described first sampling module is used for the filtered signal of described analog filter is carried out over-sampling;
Described digital filtering module is used for the sampled signal of described first sampling module is carried out digital filtering;
Described second sampling module is used for the filtered signal of described digital filtering module is sampled, and the filtered signal sampling rate of described digital filtering module is transformed to the character rate of system.
5, signal receiving end as claimed in claim 4 is characterized in that, the over-sampling frequency that described first sampling module is adopted is at least baseband signal bandwidth and described analog filter cut-off frequency sum.
6, signal receiving end as claimed in claim 4 is characterized in that, the character rate that the transition band bandwidth of described digital filtering module is no more than system deducts 2 times baseband signal bandwidth.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103685095A (en) * | 2013-12-18 | 2014-03-26 | 北京创毅视讯科技有限公司 | Method and device for achieving adjacent-channel interference suppression |
| CN112367079A (en) * | 2011-09-01 | 2021-02-12 | 华为技术有限公司 | Generating digital clocks for systems having RF circuitry |
-
2006
- 2006-12-14 CN CN200610165232A patent/CN100589463C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112367079A (en) * | 2011-09-01 | 2021-02-12 | 华为技术有限公司 | Generating digital clocks for systems having RF circuitry |
| CN103685095A (en) * | 2013-12-18 | 2014-03-26 | 北京创毅视讯科技有限公司 | Method and device for achieving adjacent-channel interference suppression |
| CN103685095B (en) * | 2013-12-18 | 2017-01-04 | 北京创毅视讯科技有限公司 | A kind of method and apparatus realizing monkey chatter suppression |
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Denomination of invention: An interference restraint method of the adjacent channels and signal receiving end Effective date of registration: 20130205 Granted publication date: 20100210 Pledgee: China Development Bank Co Pledgor: Beijing InnoFidei Technology Co. Ltd.|Beijing smartwell xunlian Polytron Technologies Inc|Anhui smartwell Communication Technology Co. Ltd. Registration number: 2013990000087 |
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