CN104954033B - A kind of speed automatic gain for ofdm system controls circuit and method - Google Patents
A kind of speed automatic gain for ofdm system controls circuit and method Download PDFInfo
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- CN104954033B CN104954033B CN201510285016.6A CN201510285016A CN104954033B CN 104954033 B CN104954033 B CN 104954033B CN 201510285016 A CN201510285016 A CN 201510285016A CN 104954033 B CN104954033 B CN 104954033B
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Abstract
The invention belongs to wireless communication technology field, specially a kind of rapid automatic gain control method based on ofdm system.The present invention uses the OFDM receiver model based on AGC modules, in ofdm signal transmitting procedure, because transmission channel is complicated and changeable, inevitably occurs the decay and distortion that receive signal, and the generations of AGC modules is to solve problem of signal attenuation.But, the convergence rate that traditional AGC is present relatively slow, gain jitter and empty slot mistake adjust three shortcomings.The present invention is directed to these three shortcomings, it is proposed that a kind of rapid automatic gain control method is simultaneously accordingly emulated, it was demonstrated that this new method can effectively overcome these three shortcomings.Apparatus of the present invention include analogue amplifier based on the OFDM receiver module with AGC modules and gain adjusting part this two parts.
Description
Technical field
The invention belongs to wireless communication technology field, and in particular to a kind of speed automatic gain for ofdm system is controlled
Circuit and method.
Background technology
Following development of forth generation GSM (4G) and evolution issues turn into the focus of current research.Used in 4G
Key technology in, OFDM technology is undoubtedly most important.The main thought of OFDM technology is exactly by given channel in frequency domain
It is divided into many narrow orthogonal sub-channels, is modulated on each of the sub-channels using a subcarrier, and each subcarrier is parallel
Transmission, therefore the interference between signal waveform can be eliminated significantly.OFDM can also be distributed adaptively on different sub-channels
Load is transmitted, can so optimize total transmission rate.In addition, OFDM can also contrary frequency Selective intensity or arrowband interference.
Because the carrier wave of each sub-channels is mutually orthogonal in ofdm system, their frequency spectrum is overlapped, is so not only reduced
Interfering between subcarrier, while improving the availability of frequency spectrum again.
But in ofdm signal transmitting procedure, because transmission channel is complicated and changeable, inevitably occur to receive signal
Decay and distortion, AGC（Automatic growth control）The generation of module is exactly to solve problem of signal attenuation.AGC modules can be with
By docking number adaptive adjustment of progress of collecting mail, so that the dynamic range of stable output signal, to reduce due to signal dynamics
Quantization error caused by scope is too small or excessive.
Traditional AGC uses fixed step size method of adjustment mostly, when running into channel and significantly changing, it is impossible to which quick adjustment increases
Beneficial parameter is, it is necessary to be lot more time to converge to stationary value；And yield value is easily caused using the method for adjustment of fixed step size
Shake.Further, since the problem of tradition AGC does not account for empty slot, the time slot without actual data transfer is carried out need not
The adjustment wanted, may result in the raising of error rate of system.
The present invention is directed to tradition AGC these shortcomings, it is proposed that a kind of rapid automatic gain control method, and accordingly carries out
Emulation, it was demonstrated that this new method can effectively overcome these three shortcomings.
The content of the invention
It is an object of the invention to the speed automatic gain control for ofdm system of proposition（Automatic Gain
Control, AGC）Circuit module and rapid automatic gain control method.
OFDM receiver module with agc circuit module is as shown in Figure 1.Wherein, agc circuit module by analogue amplifier and
Gain tuning two parts are constituted；Analogue amplifier part is arranged at before the A/D modules of OFDM receiver, for being received to antenna
To signal be amplified so that the dynamic range for receiving signal is stable in a fixed range, to prevent from receiving signal too
The small dropout caused, and receive the excessive saturation distortion caused of signal；Gain adjusting part is arranged at OFDM receiver
After A/D modules, the output signal of the A/D modules for receiving OFDM receiver, and signal level is calculated and compared,
The yield value of analogue amplifier is adjusted, with the change for the reception dynamic range of signals for tackling channel variation generation.Herein, gain is adjusted
Whole point may also be arranged on before the A/D modules of OFDM receiver, directly receive the output signal of analogue amplifier, but increasing now
Benefit adjustment need to realize that cost will height compared with digital circuit using analog circuit.
Rapid automatic gain control method proposed by the present invention based on above-mentioned speed automatic gain control circuit module, tool
Body step is as follows：
Step 1：For AGC modules, gain initial value is set.AGC gain initial value could be arranged to appointing in 20dB~40dB
Meaning reasonable value.The preferred value of AGC gain initial value is 30dB.
Step 2：Measure the average power signal of each frequency.Sample each frequencyBeforeThe energy of individual data, willIt is individual
Data point energyd j Root mean square be used as frequencyAverage power signal.Wherein,For detection data length.Therefore, frequency's
Average power signalCalculation formula it is as follows：
。
Step 3：Judge whether power average value is less than noise gate, if, then it is assumed that the signal received is white noise,
Gain tuning is not carried out to it, while skipping AGC gain value adjustment member, skip to step 7.Otherwise it is assumed that being normal data letter
Number, the docking collection of letters number carries out a Gain tuning, and continues step 4.
Wherein, the settable any reasonable value higher than white noise mean power of noise gate, concrete numerical value is limited by reception
The anti-noise level of machine preamplifier.
Step 4：The maximum of average power signal and target power value are compared, its difference is that AGC adjusts increment.
Wherein, target power value is provided as signal any reasonable value of saturation distortion does not occur.Its preferred value is 0dB, i.e.,：Letter
Number saturation power.
Step 5：If AGC adjustment increments are adjusted beyond adjustment thresholding to AGC gain value.Otherwise not adjust.Its
In, the effect of adjustment thresholding is the adjustment frequency for controlling AGC.Adjust thresholding and set bigger, then what AGC gain value was finely tuned can
Can be lower, that is, the adjustment frequency of AGC gain value is reduced, but also result in AGC gain value now simultaneously and non-optimal, it is impossible to
Adjustment receives signal to optimal dynamic range.Conversely, can then improve signal adjustment quality, but the frequency of AGC gain value can be caused
Numerous adjustment.This is decided according to the actual requirements.
Step 6：If AGC gain value exceeds AGC gain range, AGC gain value is set to AGC gain range.Otherwise
Keep current AGC gain value.When AGC gain value is beyond actual reachable maxgain value, i.e.,：During gain range, it may lead
Cause system mistake.Therefore add and judge to ensure that AGC gain value is in normal range (NR) all the time herein.
Step 7：AGC processes are completed, the reception signal after output gain adjustment to rear class processing.
So far, the process of an AGC processing terminates.
The inventive method can flexibly and rapidly adjust AGC yield value, so as to ensure the signal work(after AGC is adjusted
Rate is stable in an optimum range, reduces the quantization error of rear class.
Brief description of the drawings
Fig. 1：OFDM receiver model with AGC modules.
Fig. 2：Rapid automatic gain control method flow chart.
Fig. 3：Quick AGC performances under awgn channel.
Embodiment
With reference to the accompanying drawings and examples, the present invention is further specifically described.
As shown in figure 1, being the OFDM receiver with agc circuit module.Wherein, agc circuit module by analogue amplifier and
Gain tuning two parts are constituted；Analogue amplifier part is arranged at before the A/D modules of OFDM receiver, for being received to antenna
To signal be amplified so that the dynamic range for receiving signal is stable in a fixed range, to prevent from receiving signal too
The small dropout caused, and receive the excessive saturation distortion caused of signal；Gain adjusting part is arranged at OFDM receiver
After A/D modules, the output signal of the A/D modules for receiving OFDM receiver, and signal level is calculated and compared,
The yield value of analogue amplifier is adjusted, with the change for the reception dynamic range of signals for tackling channel variation generation.
Rapid automatic gain control method proposed by the present invention based on above-mentioned speed automatic gain control circuit module, tool
Body step is as follows：
Step 1：For AGC modules, gain initial value is set.AGC gain initial value could be arranged to appointing in 20dB~40dB
Meaning reasonable value.The preferred value of AGC gain initial value is 30dB.
Step 2：Measure the average power signal of each frequency.Sample each frequencyBeforeThe energy of individual data, willIt is individual
Data point energyd j Root mean square be used as frequencyAverage power signal.Wherein,For detection data length.Therefore, frequency's
Average power signalCalculation formula it is as follows：
。
Step 3：Judge whether power average value is less than noise gate, if, then it is assumed that the signal received is white noise,
Gain tuning is not carried out to it, while skipping AGC gain value adjustment member, skip to step 7.Otherwise it is assumed that being normal data letter
Number, the docking collection of letters number carries out a Gain tuning, and continues step 4.
Wherein, the settable any reasonable value higher than white noise mean power of noise gate, concrete numerical value is limited by reception
The anti-noise level of machine preamplifier.
Step 4：The maximum of average power signal and target power value are compared, its difference is that AGC adjusts increment.
Wherein, target power value is provided as signal any reasonable value of saturation distortion does not occur.Its preferred value is 0dB, i.e.,：Letter
Number saturation power.
Step 5：If AGC adjustment increments are adjusted beyond adjustment thresholding to AGC gain value.Otherwise not adjust.Its
In, the effect of adjustment thresholding is the adjustment frequency for controlling AGC.Adjust thresholding and set bigger, then what AGC gain value was finely tuned can
Can be lower, that is, the adjustment frequency of AGC gain value is reduced, but also result in AGC gain value now simultaneously and non-optimal, it is impossible to
Adjustment receives signal to optimal dynamic range.Conversely, can then improve signal adjustment quality, but the frequency of AGC gain value can be caused
Numerous adjustment.This is decided according to the actual requirements.
Step 6：If AGC gain value exceeds AGC gain range, AGC gain value is set to AGC gain range.Otherwise
Keep current AGC gain value.When AGC gain value is beyond actual reachable maxgain value, i.e.,：During gain range, it may lead
Cause system mistake.Therefore add and judge to ensure that AGC gain value is in normal range (NR) all the time herein.
Step 7：AGC processes are completed, the reception signal after output gain adjustment to rear class processing.
So far, the process of an AGC processing terminates.
In step 3, judge whether power average value adopts with the following method less than noise gate：
Step 3.1：Set a counter to record the quantity of the power points higher than noise gate, and reset.
Step 3.2：The power average value of each frequency and noise gate are compared successively, if higher than noise gate,
Then counter is added one.
Step 3.3：If counter values are more than frequency sum, then judge whether power average value is more than noise gate,
On the contrary then judgement is less than noise gate.It may be configured as any reasonable value in 50%~80%.
Fig. 3 is the systematic function for employing quick AGC OFDM receiver under awgn channel.It can be found that working as channel
During the very little that decays, because the analogue amplifier in the quick AGC of emulation does not make the function that signal reduces, therefore cause certain
Saturation distortion, but this phenomenon can by adjust analogue amplifier gain parameter solve.
Claims (1)
1. a kind of rapid automatic gain control method for ofdm system, the automatic gain control circuit module is by Simulation scale-up
Device and Gain tuning two parts composition；Wherein, analogue amplifier part is arranged at before the A/D modules of OFDM receiver, is used for
The signal that antenna is received is amplified, so that the dynamic range for receiving signal is stable in a fixed range, to prevent
The too small dropout caused of signal is received, and receives the excessive saturation distortion caused of signal；Gain adjusting part is arranged at
After the A/D modules of OFDM receiver, the output signal of the A/D modules for receiving OFDM receiver, and signal level is entered
Row is calculated and compared, and adjusts the yield value of analogue amplifier, with the change for the reception dynamic range of signals for tackling channel variation generation
Change；Or, gain adjusting part is arranged on before the A/D modules of OFDM receiver, directly receives the output signal of analogue amplifier；
It is characterized in that concretely comprising the following steps：
Step 1：Gain initial value is set for AGC modules, the gain initial value is any reasonable value in 20dB~40dB；
Step 2：Measure the average power signal of each frequency：Sample each frequencyBeforeNThe energy of individual data, willNIndividual data point energy
Amountd j Root mean square be used as frequencyAverage power signal；Wherein,NFor detection data length, frequencyAverage power signalCalculation formula it is as follows：
Step 3：Judge whether power average value is less than noise gate, if, then it is assumed that the signal received is white noise, not right
It carries out Gain tuning, while skipping AGC gain value adjustment member, skips to step 7；Otherwise it is assumed that be normal data-signal,
The docking collection of letters number carries out a Gain tuning, and continues step 4；Wherein, the noise gate is set above white noise mean power
Any reasonable value；
Step 4：The maximum of average power signal and target power value are compared, its difference is that AGC adjusts increment；Its
In, target power value is configured as signal and any reasonable value of saturation distortion does not occur；
Step 5：If AGC adjustment increments are adjusted beyond adjustment thresholding to AGC gain value；Otherwise not adjust；Wherein,
Adjustment thresholding is set according to actual needs；
Step 6：If AGC gain value exceeds AGC gain range, AGC gain value is set to AGC gain range；Otherwise keep
Current AGC gain value；
Step 7：AGC processes are completed, the reception signal after output gain adjustment to rear class processing；
In the step 3, judge whether power average value is as follows less than the method that noise gate is used：
Step 3.1：Set a counter to record the quantity of the power points higher than noise gate, and reset；
Step 3.2：The power average value of each frequency and noise gate are compared successively, if higher than noise gate, will
Counter adds one；
Step 3.3：If counter values are more than frequency sum, then judge that power average value is more than noise gate, it is on the contrary then sentence
Surely it is less than noise gate；It is set to any reasonable value in 50%~80%.
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| CN201510285016.6A CN104954033B (en) | 2015-05-29 | 2015-05-29 | A kind of speed automatic gain for ofdm system controls circuit and method |
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| CN104954033B true CN104954033B (en) | 2017-07-28 |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108768425B (en) * | 2018-07-02 | 2021-03-30 | 成都国恒空间技术工程有限公司 | Dynamic adjusting method for automatic gain control AGC |
| CN110474691B (en) * | 2019-08-09 | 2021-06-25 | 三维通信股份有限公司 | Gain control method and device |
| CN110620745B (en) * | 2019-09-12 | 2022-03-04 | 苏州门海微电子科技有限公司 | Digital front-end system for suppressing narrow-band interference and suppression method thereof |
| CN113014282B (en) * | 2021-02-18 | 2023-04-11 | 深圳捷扬微电子有限公司 | Automatic gain control method, device, receiver and ultra-wideband communication system |
| CN117580143B (en) * | 2024-01-15 | 2024-03-22 | 南京思宇电气技术有限公司 | Automatic gain control method and system based on dual-mode communication unit |
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| CN101005284A (en) * | 2006-01-19 | 2007-07-25 | 联发科技股份有限公司 | Automatic gain control apparatus |
| CN101373606A (en) * | 2007-08-24 | 2009-02-25 | 联发科技股份有限公司 | Method and system for signal gain control in optical disc drives |
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Patent Citations (6)
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| CN1725633A (en) * | 2004-07-23 | 2006-01-25 | 三洋电机株式会社 | Automatic level control circuit with improved recovery action |
| CN1697440A (en) * | 2005-05-25 | 2005-11-16 | 北京北方烽火科技有限公司 | Automatic gain control device in use for multicarrier receiver |
| CN101005284A (en) * | 2006-01-19 | 2007-07-25 | 联发科技股份有限公司 | Automatic gain control apparatus |
| CN101479947A (en) * | 2006-06-27 | 2009-07-08 | 新泻精密株式会社 | Automatic gain control circuit |
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