Digital control method for analog AGC of MF-TDMA return link receiver
阅读说明：本技术 Mf-tdma返向链路接收机模拟agc的数字控制方法 (Digital control method for analog AGC of MF-TDMA return link receiver ) 是由 贺俊文 于 2021-09-14 设计创作，主要内容包括：一种MF-TDMA返向链路接收机模拟AGC的数字控制方法,包括：初始化步骤和动态增益调整步骤：初始化步骤包括：根据网络规划估算模拟AGC的最小增益G-(min)和最大增益G-(max),以获得模拟AGC增益的动态调整范围；动态增益调整步骤包括：根据每一次资源分配后的网络配置情况,并以所述模拟AGC最小增益G-(min)为参考基准,估算模拟AGC的增益调整增量,并根据估算的增益调整增量在所述动态调整范围内对模拟AGC的增益进行调整。本方法根据每一次资源分配后的网络配置情况对模拟AGC进行预测控制,不仅解决了模拟AGC无限放大噪声的问题,而且解决了频繁调整模拟AGC导致的接收信号幅度抖动问题,具有良好的稳定性。(A digital control method for analog AGC of an MF-TDMA return link receiver, comprising: an initialization step and a dynamic gain adjustment step: the initialization step comprises: estimating minimum gain G of analog AGC according to network planning min And a maximum gain G max To obtain the dynamic adjustment range of the analog AGC gain; the dynamic gain adjustment step comprises: according to the network configuration condition after each resource allocation, and the analog AGC minimum gain G min And estimating the gain adjustment increment of the analog AGC as a reference, and adjusting the gain of the analog AGC in the dynamic adjustment range according to the estimated gain adjustment increment. The method carries out predictive control on the analog AGC according to the network configuration condition after each resource allocation, not only solves the problem of infinite amplification noise of the analog AGC, but also solves the problem of amplitude jitter of a received signal caused by frequently adjusting the analog AGC, and has good stability.)
1. A digital control method for simulating AGC of an MF-TDMA return link receiver is characterized by comprising the following steps of initialization and dynamic gain adjustment:
the initialization step comprises: estimating minimum gain G of analog AGC according to network planningminAnd a maximum gain GmaxObtaining the dynamic adjustment range of analog AGC gain;
the dynamic gain adjustment step comprises: according to the network configuration condition after each resource allocation, and the analog AGC minimum gain GminAnd estimating the gain adjustment increment of the analog AGC as a reference, and adjusting the gain of the analog AGC in the dynamic adjustment range according to the estimated gain adjustment increment.
2. The digital control method for analog AGC of an MF-TDMA return link receiver according to claim 1, wherein the dynamic gain adjustment step comprises:
according to the network configuration condition after each resource allocation, estimating the amplitude ratio of the signal to the noise to obtain:
wherein A issAnd AnIndividual watchShowing the amplitude of the signal and noise, B, under the new configurationiIs the bandwidth of the ith carrier within the expected sampling bandwidth of the ADC,is the symbol SNR budget value of the waveform with the maximum symbol SNR budget value adopted by the ith carrier under the new configuration, BADCIs the desired sampling bandwidth of the ADC;
with minimum gain G of analog AGCminEstimating the gain increment needed to be adjusted by analog AGC when the amplitude of the received signal reaches the target amplitude for reference, solving the equation set
Wherein A isobjIs the target amplitude for the analog AGC to amplitude adjust the received signal,is the signal amplitude calculated according to the amplitude ratio k under the assumption of minimum gain,the sum of the signal noise amplitudes calculated according to the amplitude ratio k under the assumption of minimum gain is used to obtain the gain increment which needs to be adjusted by the analog AGC:
with minimum gain G of analog AGCminEstimating the target gain G to which the analog AGC needs to be adjusted when the amplitude of the received signal reaches the target amplitude for referenceobjTo obtain
Target gain G from analog AGCobjAnd the current gain GcurrentEstimating a gain adjustment delta Δ G to obtain
ΔG＝Gobj-Gcurrent；
And adjusting the gain of the analog AGC in the dynamic adjustment range according to the gain adjustment increment delta G.
3. The digital control method for analog AGC of an MF-TDMA return link receiver according to claim 2, c h a r a c t e r i z e d i n that for carriers not enabled,
4. the digital control method for analog AGC of MF-TDMA return link receiver of claim 1, wherein a minimum gain G of the analog AGCminThe estimation method comprises the steps of:
determining the symbol SNR budget for the waveform with the maximum symbol SNR budget for the network planning, which is the linear value of the symbol SNR, using (E)s/N0)maxRepresents;
according to network planning, determining a scene with the maximum received expected signal power: the expected sampling bandwidth range of the ADC is completely occupied by a carrier, and the carrier adopts a waveform with the maximum symbol signal-to-noise ratio precalculated value in network planning, so that the gain of the analog AGC is minimum and the noise amplitude is minimum in the scene;
estimating the amplitude ratio of the signal to the noise under the scene of the maximum power of the received expected signal to obtain
Wherein the content of the first and second substances,is the receiving periodSignal amplitude in the scene of the maximum signal power is expected;
estimating a minimum noise amplitude in a scenario where the received desired signal power is at a maximumSolving a system of equations
To obtain
Wherein A isobjThe target amplitude of the amplitude adjustment of the received signal is performed by the analog AGC;
under the condition that the system is idle and only receives noise, the gain of the analog AGC is adjusted to enable the noise peak value to reachWith the gain at that time as the minimum gain G of the analog AGCmin。
5. The digital control method for analog AGC of MF-TDMA return link receiver of claim 1, wherein a maximum gain G of the analog AGCmaxThe estimation method comprises the steps of:
determining the expected sampling bandwidth B of ADC according to network planningADCAnd bandwidth B of the carrier with the smallest bandwidth in its rangemin；
According to the network planning, determining the symbol SNR budget value of the waveform with the minimum symbol SNR budget value, which is the linear value of the symbol SNR, for(Es/N0)minRepresents;
according to network planning, determining a scene with minimum received expected signal power: in the expected sampling bandwidth range of the ADC, only the carrier with the minimum bandwidth is communicated, and the carrier adopts the waveform with the minimum symbol signal-to-noise ratio precalculated value in network planning, so that the analog AGC has the maximum gain and the maximum noise amplitude in the scene;
estimating the amplitude ratio of the signal to the noise under the scene of the minimum power of the received expected signal to obtain
Wherein the content of the first and second substances,is the signal amplitude in the scenario where the received desired signal power is minimal;
estimating a maximum noise amplitude in a scenario where the received desired signal power is minimalSolving a system of equations
To obtain
Under the condition that the system is idle and only receives noise, the gain of the analog AGC is adjusted to enable the noise peak value to reachWith the gain at that time as the maximum gain G of the analog AGCmax。
6. The digital control method for analog AGC of an MF-TDMA return link receiver according to claim 1, wherein the initializing step further comprises: setting an initial gain of the analog AGC to a maximum gain G of the analog AGCmax。
7. The digital control method for analog AGC of an MF-TDMA return link receiver according to claim 1, further comprising the pre-step of: before the initialization step, the passband bandwidth of the anti-aliasing low-pass filter located before the ADC is set to the desired sampling bandwidth of the ADC.
Technical Field
The invention belongs to the technical field of digital communication, relates to a gain control technology of an MF-TDMA receiver, and particularly relates to a digital control method for simulating AGC of an MF-TDMA return link receiver.
Background
The return link of an MF-TDMA satellite communication system typically comprises a plurality of carriers in each of which users transmit information in bursts. If the return link receiver adopts a broadband low-pass direct sampling mode to perform analog-to-digital conversion on the mixed signals of a plurality of carriers, the signals of the carriers share the analog AGC and the ADC of the receiver, and further share the quantization bit width resource of the ADC.
The analog AGC is located in front of the ADC, and the main function of the analog AGC is to amplify the amplitude of a received (noisy) expected signal as much as possible on the premise of ensuring that the amplitude overflow distortion does not occur to the expected signal so as to fully utilize the quantization bit width resource of the ADC. In the above background, the operating scenario of the MF-TDMA return link receiver for simulating AGC has the following characteristics: 1) the multi-channel signals share one analog AGC channel, and further share the gain of the analog AGC; 2) the return link signal has strong dynamic variability. This dynamic variability manifests itself, on the one hand, as dynamic changes in the carriers, i.e., carrier switching on and off as a result of TDMA burst communication mechanisms; on the other hand, the number of users in a carrier increases or decreases, and the waveform of the users changes. These factors can cause significant fluctuations in the received signal power, presenting practical difficulties in the control of analog AGC.
The conventional control method for analog AGC is a closed-loop feedback control method based on a target amplitude (or reference amplitude): firstly, determining a target amplitude of a received signal; then estimating the true amplitude of the received signal; finally, according to the relation between the real amplitude of the received signal and the target amplitude, the gain of the analog AGC is adjusted: if the real amplitude of the received signal is smaller than the target amplitude, increasing the gain of the analog AGC; if the true amplitude of the received signal is greater than the target amplitude, the gain of the analog AGC is reduced.
However, the ideal effect of applying the method to the analog AGC control of the MF-TDMA return link receiver is difficult to achieve, and the main reason is the dynamic variability of the MF-TDMA return link burst signal. For example, when a burst signal is not expected for a period of time, only a noise signal is received in the signal received by the receiver. Because the amplitude of the noise signal is very small, usually much smaller than the target amplitude of the AGC, the closed-loop feedback control method based on the target amplitude will continuously increase the gain of the analog AGC until the noise amplitude is amplified to the target amplitude; then, if a desired burst signal arrives at the receiver, amplitude overflow distortion must occur.
Disclosure of Invention
In order to solve the above related prior art problems, the present invention provides a digital control method for analog AGC of MF-TDMA return link receiver, which performs predictive control on the analog AGC according to the network configuration condition after each resource allocation, not only solves the problem of infinite amplification noise of the analog AGC, but also solves the problem of amplitude jitter of the received signal caused by frequently adjusting the analog AGC, and has good stability.
In order to achieve the purpose of the invention, the invention is realized by the following technical scheme:
a digital control method for simulating AGC of an MF-TDMA return link receiver comprises an initialization step and a dynamic gain adjustment step.
Wherein the initialization step includes a minimum gain estimation method and a maximum gain estimation method:
1. the minimum gain estimation method comprises the following specific steps:
1) and determining the symbol signal-to-noise ratio budget value of the waveform with the maximum symbol signal-to-noise ratio budget value according to network planning. This value is a linear value of the symbol signal-to-noise ratio, used as (E)s/N0)maxAnd (4) showing.
2) According to network planning, determining a scene with the maximum received (noisy) expected signal power: the expected sampling bandwidth range of the ADC is completely occupied by one carrier wave, and the carrier wave adopts a waveform with the maximum symbol signal-to-noise ratio precalculated value in network planning. In this scenario, the gain of the analog AGC is minimal, and therefore, the noise amplitude is also minimal.
3) Estimating the amplitude ratio of the signal to the noise under the scene to obtain
Wherein the content of the first and second substances,is the signal amplitude in the above scenario.
4) Estimating minimum noise amplitude in the above scenarioSolving a system of equations
To obtain
Wherein A isobjIs the target amplitude for the analog AGC to amplitude adjust the received signal.
5) Under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the minimum gain G of the analog AGCmin(in dB).
2. The maximum gain estimation method comprises the following specific steps:
1) determining the expected sampling bandwidth B of ADC according to network planningADCAnd bandwidth B of the carrier with the smallest bandwidth in its rangemin。
2) And determining the symbol signal-to-noise ratio budget value of the waveform with the minimum symbol signal-to-noise ratio budget value according to network planning. This value is a linear value of the symbol signal-to-noise ratio, used as (E)s/N0)minAnd (4) showing.
3) According to the network planning, determining the scene with the minimum received (noisy) expected signal power: within the expected sampling bandwidth range of the ADC, only the carrier with the minimum bandwidth is communicated, and the carrier adopts a waveform with the minimum symbol signal-to-noise ratio (SNR) precalculated value in network planning. In this scenario, the gain of the analog AGC is the largest, and thus the noise amplitude is also the largest.
4) Estimating the amplitude ratio of the signal to the noise under the scene to obtain
Wherein the content of the first and second substances,is the signal amplitude in the above scenario.
5) Estimating maximum noise amplitude in the above scenarioSolving a system of equations
To obtain
6) Under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the maximum gain G of the analog AGCmax(in dB).
The dynamic gain adjustment method comprises the following two steps: 1. estimating gain adjustment increment of the analog AGC according to the network configuration condition after each resource allocation; 2. the gain of the analog AGC is adjusted based on the estimated gain adjustment increment.
Further, the gain adjustment increment estimation method comprises the following specific steps:
1) estimating the amplitude ratio of the signal to the noise according to the network configuration condition after each resource allocation to obtain
Wherein A issAnd AnRespectively representing the amplitudes of signal and noise under the new configuration, BiIs the bandwidth of the ith carrier within the expected sampling bandwidth of the ADC,the symbol SNR budget value of the waveform with the maximum symbol SNR budget value adopted by the ith carrier wave under the new configuration is obtained. For the carriers that are not enabled,
2) the gain increment (in dB) that the analog AGC needs to adjust when the amplitude of the received (noisy) signal reaches the target amplitude is estimated with the minimum gain of the analog AGC as a reference. Solving a system of equations
To obtain
3) Estimating the target gain G to be adjusted by the analog AGC when the amplitude of the received (with noise) signal reaches the target amplitude by taking the minimum gain of the analog AGC as a referenceobj(unit is dB) to
4) Target gain G from analog AGCobjAnd the current gain GcurrentEstimating gain adjustment deltaΔ G (in dB) to
ΔG＝Gobj-Gcurrent。
The invention has the beneficial effects that:
the analog AGC is subjected to predictive control according to the network configuration condition after each resource allocation, the problem of infinite amplification noise of the analog AGC is solved, the problem of amplitude jitter of a received signal caused by frequent adjustment of the analog AGC is solved, and the method has good stability.
Drawings
FIG. 1 is an algorithmic flow chart of one embodiment of the method of the present invention.
Detailed Description
In order to make the purpose, technical scheme and specific implementation method of the application clearer, the application is further described in detail by combining with an example of the attached drawings.
The embodiment of the application provides a digital control method for simulating AGC of an MF-TDMA return link receiver, and the design idea of the method is as follows: the analog AGC is dynamically adjusted by taking a resource allocation period as a period, namely the gain of the analog AGC is estimated and adjusted according to the network configuration condition after each resource allocation, and the method is an open-loop feedforward control method based on target amplitude. The network configuration parameters relied on by the method are as follows: the expected sampling bandwidth of the ADC, the bandwidth of the carrier, the allocation scheme of the waveform, and a symbol snr budget for the waveform, where the symbol snr budget for the waveform is equal to a demodulation threshold symbol snr for the waveform plus a symbol snr margin.
The method consists of an initialization method and a dynamic gain adjustment method. The initialization method is used to estimate the dynamic adjustment range of the analog AGC gain, i.e., the minimum gain and the maximum gain of the analog AGC, according to the network plan. The dynamic gain adjustment method is used for estimating the gain adjustment increment of the analog AGC according to the network configuration after the resource allocation and adjusting the gain of the analog AGC according to the increment. Theoretically, the adjustment result of the analog AGC gain should be within the above dynamic adjustment range.
The minimum gain estimation method comprises the following steps: first, according to the networkPlanning and determining the scene with the maximum received (noisy) expected signal power: the expected sampling bandwidth range of the ADC is completely occupied by one carrier wave, and the carrier wave adopts a waveform with the maximum symbol signal-to-noise ratio precalculated value in network planning. In this scenario, the gain of the analog AGC is minimal, and therefore, the noise amplitude is also minimal. Then, the minimum noise amplitude in this scenario is estimatedFinally, under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the minimum gain of the analog AGC.
The maximum gain estimation method comprises the following steps: first, the scenario with the minimum received (noisy) desired signal power is determined according to the network planning: within the expected sampling bandwidth range of the ADC, only the carrier with the minimum bandwidth is communicated, and the carrier adopts a waveform with the minimum symbol signal-to-noise ratio (SNR) precalculated value in network planning. In this scenario, the gain of the analog AGC is the largest, and thus the noise amplitude is also the largest. Then, the maximum noise amplitude in this scenario is estimatedFinally, under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the maximum gain of the analog AGC.
The dynamic gain adjustment method comprises the following two steps:
1) and estimating the gain adjustment increment of the analog AGC according to the network configuration condition after each resource allocation.
2) The gain of the analog AGC is adjusted based on the estimated gain adjustment increment.
The method for estimating the gain adjustment increment comprises the following steps: firstly, the amplitude ratio of the signal to the noise in the range of the ADC expected sampling bandwidth is estimated according to the network configuration condition after resource allocation. Then, a target gain value to which the analog AGC needs to be adjusted when the amplitude of the received (noisy) signal reaches the target amplitude is estimated with the minimum gain of the analog AGC as a reference. And finally, estimating gain adjustment increment according to the target gain value and the current gain value of the analog AGC.
The following describes the implementation process of the present application in detail by taking the flow shown in fig. 1 as an example:
firstly, a precondition is prepared for using the method of the invention: the passband bandwidth of the anti-aliasing low pass filter located before the ADC is set to the desired sampling bandwidth of the ADC.
And secondly, initializing a digital control algorithm of the analog AGC. The initialization mainly completes the following three tasks: estimating the minimum gain and the maximum gain of the analog AGC and setting an initial value of the analog AGC gain.
1. Estimating the minimum gain of the analog AGC:
1) and determining the symbol signal-to-noise ratio budget value of the waveform with the maximum symbol signal-to-noise ratio budget value according to network planning. This value is a linear value of the symbol signal-to-noise ratio, used as (E)s/N0)maxAnd (4) showing.
2) According to network planning, determining a scene with the maximum received (noisy) expected signal power: the expected sampling bandwidth range of the ADC is completely occupied by one carrier wave, and the carrier wave adopts a waveform with the maximum symbol signal-to-noise ratio precalculated value in network planning. In this scenario, the gain of the analog AGC is minimal, and therefore, the noise amplitude is also minimal.
3) Estimating the amplitude ratio of the signal to the noise under the scene to obtain
Wherein the content of the first and second substances,is the above scenarioThe signal amplitude of (d).
4) Estimating minimum noise amplitude in the above scenarioSolving a system of equations
To obtain
Wherein A isobjIs the target amplitude for the analog AGC to amplitude adjust the received signal.
5) Under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the minimum gain G of the analog AGCmin(in dB).
2. Estimating the maximum gain of the analog AGC:
1) determining the expected sampling bandwidth B of ADC according to network planningADCAnd bandwidth B of the carrier with the smallest bandwidth in its rangemin。
2) And determining the symbol signal-to-noise ratio budget value of the waveform with the minimum symbol signal-to-noise ratio budget value according to network planning. This value is a linear value of the symbol signal-to-noise ratio, used as (E)s/N0)minAnd (4) showing.
3) According to the network planning, determining the scene with the minimum received (noisy) expected signal power: within the expected sampling bandwidth range of the ADC, only the carrier with the minimum bandwidth is communicated, and the carrier adopts a waveform with the minimum symbol signal-to-noise ratio (SNR) precalculated value in network planning. In this scenario, the gain of the analog AGC is the largest, and thus the noise amplitude is also the largest.
4) Estimating the amplitude ratio of the signal to the noise under the scene to obtain
Wherein the content of the first and second substances,is the signal amplitude in the above scenario.
5) Estimating maximum noise amplitude in the above scenarioSolving a system of equations
To obtain
6) Under system no-load (i.e., noise only reception) conditions, the gain of the analog AGC is adjusted so that the noise peak (nearly) reachesThe level of (c). The gain at this time is the maximum gain G of the analog AGCmax(in dB).
3. Setting an initial value of analog AGC gain: setting initial gain of analog AGC to Gmax。
And thirdly, estimating and adjusting the gain of the analog AGC by taking the resource allocation period as a period.
The dynamic gain adjustment method comprises two steps: 1. estimating gain adjustment increment of the analog AGC according to the network configuration condition after each resource allocation; 2. the gain of the analog AGC is adjusted based on the estimated gain adjustment increment.
The gain adjustment increment estimation method comprises the following specific steps:
1) estimating the amplitude ratio of the signal to the noise according to the network configuration condition after each resource allocation to obtain
Wherein A issAnd AnRespectively representing the amplitudes of signal and noise under the new configuration, BiIs the bandwidth of the ith carrier within the expected sampling bandwidth of the ADC,the symbol SNR budget value of the waveform with the maximum symbol SNR budget value adopted by the ith carrier wave under the new configuration is obtained. For the carriers that are not enabled,
2) the gain increment (in dB) that the analog AGC needs to adjust when the amplitude of the received (noisy) signal reaches the target amplitude is estimated with the minimum gain of the analog AGC as a reference. Solving a system of equations
To obtain
3) Estimation of the amplitude of the received (noisy) signal to a target, based on the minimum gain of the analog AGC, is performedAt amplitude, the analog AGC needs to adjust to the target gain Gobj(unit is dB) to
4) Target gain G from analog AGCobjAnd the current gain GcurrentThe gain adjustment delta Δ G (in dB) is estimated
ΔG＝Gobj-Gcurrent。
5) And adjusting the gain of the analog AGC in the dynamic adjustment range according to the gain adjustment increment delta G.