A method for adaptive power control in a satellite mobile communication system

Abstract

The application discloses a kind of satellite mobile communication system adaptive power control methods, this method is: first, the current service channel signal and noise ratio is measured to the service channel burst of local end and predicts the channel quality after long delay;Then local end enters closed loop power control procedure, judge whether to the receiving opportunity of power control channel along with road, if to the power control channel along with road opportunity, then calculate the attenuation value of transmitting power of opposite end, the attenuation value of transmitting power of local end is calculated using closed loop power control;Then using open loop power control correction local end this time transmitting power;Finally, according to the lower limit of system set transmitting power value and the upper limit of transmitting power value, the amplitude limiting and quantization of local end this time transmitting power are carried out, and the transmitting power level is set according to the power of quantization.The application improves the performance of satellite mobile communication system power control, improves system communication capacity and communication quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of satellite mobile communication system, and particularly relates to a satellite mobile communication system adaptive power control method. BACKGROUND

[0002] As an extension and supplement of ground cellular mobile communication, satellite mobile communication system is mainly used for communication in remote areas and emergency communication, and solves the problem of limited coverage of ground cellular mobile communication system in remote areas and sea areas. Generally, a typical satellite mobile communication system is composed of GEO / LEO satellite, satellite terminal / mobile earth station, gateway station (GW) and operation control system, and can provide users with services such as intranet telephone, short message, Internet access and fax, and realizes global service interconnection through interconnection with PSTN, PLMN and Internet.

[0003] In the satellite mobile communication system, various types of satellite terminals such as handheld, vehicle-mounted, airborne and ship-mounted terminals are supported. Due to the differences in the antennas and radio frequency devices carried, the receiving and transmitting capabilities of different types of satellite terminals are quite different. If the terminal transmitting power is not limited, it will inevitably lead to mutual interference between the same frequency beams, and if the satellite transmitting power is not adaptively adjusted, it will inevitably lead to a reduction in the number of users supported by the user system.

[0004] Compared with ground wireless communication channels, satellite channels have long delay characteristics. Taking the GEO satellite mobile communication system as an example, the one-way delay is at least 540 ms, and the current channel state information cannot be used as the basis for adaptive control. Obviously, the closed-loop power control algorithm used in ground mobile communication is no longer suitable for satellite mobile communication system.

[0005] Accurate channel measurement and fast channel quality feedback are the prerequisites for the system to implement effective power control. However, the long delay problem caused by satellite mobile communication system makes the feedback data of the opposite end channel measurement unable to reflect the current channel quality, which seriously reduces the power control performance of satellite mobile communication system.

[0006] Patent 1 (application number: 201680053046.7, application date: 2016-09-09) proposes a duty cycle-based power control scheme for satellite communication, and the satellite network controls the duty cycle of the waveform transmission, thereby controlling the average transmission power of the satellite when the satellite transmits to the UT, but cannot adapt to different use environments for power control; Patent 2 (application number: 201010179809.7, application date: 2010-05-21) proposes an uplink adaptive closed-loop power control method for a satellite communication system, which uses a power control algorithm based on binary search growth to solve the interference on the satellite signal link due to environmental factors, but the adaptive power control of the main user uplink cannot perform global power control. SUMMARY

[0007] The purpose of the present application is to provide a satellite mobile communication system power control method that can adaptively control the power of a satellite mobile communication system, improve system communication capacity and communication quality.

[0008] The technical solution for achieving the purpose of the present application is a satellite mobile communication system adaptive power control method, comprising the following steps:

[0009] Step 1, the terminal first receives the service channel burst and measures the ratio of the current service channel signal to noise , estimates the current signal quality according to the length of the power control channel, and predicts the channel quality after a long delay;

[0010] Step 2, the terminal enters the closed-loop power control process and judges whether it is the receiving time of the power control channel, if it is the power control channel time, calculate the transmit power attenuation value of the opposite end ;

[0011] Step 3, use the closed-loop power control to calculate the transmit power attenuation value of the terminal ;

[0012] Step 4, use the open-loop power control to correct the transmit power of the terminal this time ;

[0013] Step 5, limit and quantize , and set the transmit power level according to the quantized power.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] (1) It can adaptively control the power of a satellite mobile communication system;

[0016] (2) It improves the performance of the satellite mobile communication system power control, improves the system communication capacity and communication quality. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating an adaptive power control method for a satellite mobile communication system according to the present invention. Detailed Implementation

[0018] This invention discloses an adaptive power control method for a satellite mobile communication system, comprising the following steps:

[0019] Step 1: The local end first receives the traffic channel burst and measures the current traffic channel signal-to-noise ratio. The current signal quality is estimated based on the length of the power-controlled channel, and the channel quality is predicted after a long delay.

[0020] Step 2: The local end enters the closed-loop power control process and determines whether it is time to receive data through the associated power control channel. If it is time to receive data through the associated power control channel, the local end calculates the transmit power attenuation value. ;

[0021] Step 3: Calculate the transmit power attenuation value at this end using closed-loop power control. ;

[0022] Step 4: Correct the local transmit power using open-loop power control. ;

[0023] Step 5, for Perform amplitude limiting and quantization, and set the transmit power level according to the quantized power.

[0024] Furthermore, the aforementioned satellite mobile communication system includes GEO / LEO satellites, satellite terminals / mobile earth stations, gateway stations (GW), and operation and control systems, providing users with intranet telephone, SMS, internet access, and fax services. Through interconnection with PSTN, PLMN, and the Internet, it achieves global service interconnection.

[0025] Furthermore, in step 1, the local end first receives the service channel burst and measures the current burst. The ratio of signal to noise in each service channel The current signal quality is estimated based on the length of the power-controlled channel, and the channel quality after a long delay is predicted, as follows:

[0026] Step 1.1: In a satellite mobile communication system, the burst data of the accompanying power control channel is uniformly distributed across k consecutive service channels. To accurately estimate the current channel quality, it is necessary to average the channel quality of the bursts from the k consecutive service channels and apply correlation corrections to reduce the impact of the randomness of individual burst signals and estimate the current average signal quality. ;

[0027] Step 1.2, calculate the prediction coefficient using the current estimated value and the expected prediction distance ;

[0028] Step 1.3, calculate the channel quality prediction value of the zth frame .

[0029] Further, in the satellite mobile communication system, the burst data of the power control channel is evenly distributed in k consecutive traffic channels, each channel contains a power control block. In order to accurately estimate the current channel quality, it is necessary to average and correct the channel quality of k consecutive traffic channel bursts to reduce the influence of the randomness of a single burst signal, and estimate the current average signal quality , which is as follows:

[0030] Step 1.1.1, calculate the average channel quality of the nth group of traffic channels , each group of channels contains k consecutive traffic channels, which constitutes a power control channel:

[0031]

[0032] Step 1.1.2, calculate the channel quality variance of the nth group of traffic channels :

[0033]

[0034] Step 1.1.3, if n=1, initialize the local SNR average variance as , if n>1, update the local storage variance using the following formula, and correct the average value calculated for the block as follows:

[0035]

[0036] Use the current SNR average variance to correct the current average signal quality:

[0037]

[0038] wherein is a filter coefficient factor, is a correction factor, both of which are broadcast to terminal users by the network side.

[0039] Further, in step 1.2, the prediction coefficient is calculated using the received N groups of SNR averages of the power control channel and the expected prediction distance , and the calculation formula is:

[0040]

[0041]

[0042] wherein, represents a matrix, L is a prediction coefficient matrix used the number of the number of samples of the side power control channel SNR used to obtain represents the mth prediction coefficient matrix, m is 0 to L-1; is the mth service channel SNR average value relative to the expected prediction distance is the mth service channel SNR average value relative to the expected prediction distance and the prediction coefficient L, is the mth service channel SNR average value of the service channel relative to the prediction coefficient L.

[0043] Further, the step 1.3 calculates the channel quality prediction value of the zth frame , the formula is:

[0044]

[0045] wherein, is the mth service channel SNR average value relative to the prediction distance .

[0046] Further, the step 2 describes that the local end enters the closed loop power control process, judges whether the receiving time of the side power control channel is reached, if the side control channel time is reached, the attenuation value of the transmitting power of the opposite end is calculated , which is as follows:

[0047] Step 2.1, if the power control message is decoded correctly, the effective transmitting power of the opposite end is extracted ; if the decoding is not correct, the last decoding correct is taken as the transmitting power of this time;

[0048] Step 2.2, value is calculated as follows:

[0049] )

[0050] wherein, Gain is the closed loop power control gain factor, SNRT is the target SNR to be satisfied for a certain channel error rate requirement, SNR(n) is the channel quality prediction value predicted by using the formula in the step 1.3, n is at least the current frame number plus the time consumed by one round trip, when SNRT​ Gain = GainDn, otherwise Gain = GainUp, GainDn and GainUp represent closed loop power control down factor and closed loop power control up factor respectively;

[0051] Step 2.3, the transcoding link attenuation value of the on-the-way transmission, and filling into the on-the-way power control signaling which is about to be transmitted, waiting for sending.

[0052] Further, the step 3 describes the calculation of the attenuation value of the local transmission power by using closed loop power control , which is as follows:

[0053] Step 3.1, if the power control message can be correctly decoded and the escape character can be obtained, the , the last correctly demodulated is selected from the decoded message, and the step parameter Step is set as 0;

[0054] Step 3.2, if the power control message cannot be correctly decoded or the valid escape character cannot be obtained, the of the last correctly demodulated is taken as the of this time, and the step parameter Step is set as 0.5dB;

[0055] Step 3.3, the closed loop

[0056]

[0057] Further, the step 4 describes the correction of the local transmission power of this time by using open loop power control , which is as follows:

[0058] Step 4.1, the quality of the next frame of on-the-way control channel is predicted by using formula (6) , the SNR obtained by the previous n1 to n2 updates is averaged to obtain ;

[0059] Step 4.2, the open loop power margin is calculated as - ;

[0060] Step 4.3, if ≥ , then

[0061]

[0062] Step 4.4, if ≤ , then

[0063]

[0064] wherein, nl, n2, , , , are broadcast signal parameters, nl is L-1 in link prediction in step 1.3, n2 is N used in link prediction in step 1.3, represents open loop power margin, represents open loop down power control factor, open loop up power control factor, represents threshold value of activating open loop power control.

[0065] Further, the step 5 limits and quantizes , and the details are as follows:

[0066] According to the lower limit of transmitting power value P min and the upper limit of transmitting power value P max , the transmitting power of this time of the local side is limited and quantized, and the transmitting power level is set according to the quantized power.

[0067] The present application is further explained in detail below in combination with the drawings and specific embodiments.

[0068] Embodiment

[0069] In combination with Figure 1 , the adaptive power control method of the satellite mobile communication system of the present application comprises the following steps:

[0070] Step 1, the local side first receives the traffic channel burst, measures the ratio of current traffic channel signal to noise , estimates the current signal quality according to the length of the power control channel, and predicts the channel quality after long delay;

[0071] Step 2, the local side enters the closed loop power control process, judges whether it is the receiving time of the power control channel, if it is the power control channel time, calculates the transmitting power attenuation value of the opposite side ;

[0072] Step 3, uses the closed loop power control to calculate the transmitting power attenuation value of the local side ;

[0073] Step 4, uses the open loop power control to correct the transmitting power of this time of the local side ;

[0074] Step 5, limits and quantizes The amplitude is limited and quantized, and a transmission power level is set according to the quantized power.

[0075] As a specific example, the satellite mobile communication system, including GEO / LEO satellites, satellite terminals / mobile earth stations, gateway stations GW and operation control systems, can provide users with in-network telephone, short message, Internet access and fax services, and realize global service interconnection through interconnection with PSTN, PLMN and Internet.

[0076] As a specific example, the first step is to receive the service channel burst and measure the current signal-to-noise ratio of the service channel , estimate the current signal quality according to the length of the power control channel, and predict the channel quality after a long delay, as follows:

[0077] Step 1.1, in the satellite mobile communication system, the burst data of the power control channel are uniformly distributed in k consecutive service channels, in order to accurately estimate the current channel quality, the channel quality of k consecutive service channel bursts needs to be averaged and corrected, to reduce the influence of the randomness of single burst signal, and estimate the current average signal quality ;

[0078] Step 1.2, using the current estimated value and the expected prediction distance , calculate the prediction coefficient ;

[0079] Step 1.3, calculate the channel quality prediction value of the zth frame .

[0080] As a specific example, in the satellite mobile communication system, the burst data of the power control channel are uniformly distributed in k consecutive service channels, each channel contains a power control block, in order to accurately estimate the current channel quality, the channel quality of k consecutive service channel bursts needs to be averaged and corrected, to reduce the influence of the randomness of single burst signal, and estimate the current average signal quality , as follows:

[0081] Step 1.1.1, calculate the average channel quality of the nth group of service channels , each group of channels contains k consecutive service channels, constituting a power control channel:

[0082]

[0083] Step 1.1.2, calculate the channel quality variance of the nth group of service channels :​

[0084]

[0085] Step 1.1.3: If n=1, initialize the local SNR average variance as follows: If n>1, update the local storage variance using the following formula, and correct the mean calculated for this block as follows:

[0086]

[0087] Using the current SNR average variance To correct the current average signal quality:

[0088]

[0089] In the formula, For filter coefficient factors, These are correction factors, all of which are broadcast to end users from the network side.

[0090] As a specific example, step 1.2 involves using the average SNR of the received N sets of associated channels and the expected predicted distance. Calculate the prediction coefficient The calculation formula is:

[0091]

[0092]

[0093] in, Let L be the matrix, where L is the prediction coefficient matrix used. The quantity, N, represents the quantity used to obtain The number of samples for the SNR of the power control channel with the path. This represents the m-th prediction coefficient matrix, where m ranges from 0 to L-1. For the distance relative to the expected prediction distance The average SNR of the m-th service channel For the distance relative to the expected prediction distance And the average SNR of the m-th traffic channel with prediction coefficient L, is the average SNR of the m-th service channel relative to the prediction coefficient L.

[0094] As a specific example, step 1.3 describes calculating the channel quality prediction value for the z-th frame. The formula is:

[0095]

[0096] in, for the relative prediction distance of the SNR average value of m service channels.

[0097] As a specific example, the home side enters the closed loop power control procedure described in step 2 to determine whether it is the time to receive the power control channel. If it is the time to receive the power control channel, the attenuation value of the transmitting power of the opposite side is calculated , as follows:

[0098] Step 2.1, if the power control message is decoded correctly, the effective transmitting power of the opposite side is extracted ; if the decoding is not correct, the last decoded correctly is taken as the transmitting power this time;

[0099] Step 2.2, the value is calculated as follows:

[0100] )

[0101] where Gain is the closed loop power control gain factor, SNRT is the target SNR to meet the certain channel error rate requirement, SNR(n) is the predicted channel quality predicted by the formula in step 1.3, n is at least the current frame number plus the time consumed by one round trip, when SNRT Gain = GainDn, otherwise Gain = GainUp, GainDn and GainUp represent the closed loop power control down factor and the closed loop power control up factor respectively;

[0102] Step 2.3, the is converted into the link attenuation value to be transmitted and filled into the power control signaling to be transmitted, waiting for sending.

[0103] As a specific example, the transmitting power attenuation value of the home side is calculated by using the closed loop power control described in step 3 , as follows:

[0104] Step 3.1, if the power control message can be decoded correctly and the escape character can be obtained, the minimum value is selected from the , the last correctly demodulated , and the step parameter Step is set to 0;

[0105] Step 3.2, if the power control message cannot be decoded correctly or the effective escape character cannot be obtained, the last correctly demodulated is taken as the , and the step parameter Step is set to 0.5dB;

[0106] Step 3.3, the closed loop is calculated according to the following formula :

[0107]

[0108] As a specific example, the step 4 described using open loop power control to modify the local this time transmission power, as follows:

[0109] Step 4.1, using formula (6) to predict the next frame along with the control channel quality , the SNR obtained by the previous n1 to n2 update is averaged to get ;

[0110] Step 4.2, calculate the open loop power margin is - ;

[0111] Step 4.3, if ≥ , then

[0112]

[0113] Step 4.4, if ≤ , then

[0114]

[0115] Wherein, n1, n2, , , , are broadcast signal parameters. n1 is L-1 in step 1.3 link prediction, n2 is N used in step 1.3 link prediction, represent the open loop power margin, represent the open loop down power control factor, open loop up power control factor, represent the threshold value of the activation of open loop power control.

[0116] As a specific example, step 5 described according to P min and P max to amplitude limiting and quantization, and according to the quantized power setting transmission power level, as follows:

[0117] The P min is the lower limit of the system set transmission power value, the P max is the upper limit of the system set transmission power value, according to P min and P max to Amplitude limiting and quantization are performed, and a transmission power level is set according to the quantized power.

[0118] The above merely preferred embodiments of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered within the scope of the present application.

Claims

1. A method for adaptive power control in a satellite mobile communication system, characterized by The method comprises the following steps: Step 1, the terminal first receives the service channel burst, and measures the current service channel signal-to-noise ratio According to the length of the power control channel, the current signal quality is estimated, and the channel quality after long delay is predicted. Step 2, the terminal enters the closed loop power control process, judges whether it is the receiving time of the power control channel, if it is the time of the power control channel, calculates the attenuation value of the transmitting power of the opposite terminal ; Step 3, calculate the attenuation value of the transmitting power of the local end by using closed loop power control ; Step 4, correct the current transmit power of the local end by using open loop power control ; Step 5, for Perform amplitude limiting and quantization, and set the transmit power level according to the quantized power; Step 1 describes the local end first receiving the service channel burst and measuring the current burst. The ratio of signal to noise in each service channel The current signal quality is estimated based on the length of the power-controlled channel, and the channel quality after a long delay is predicted, as follows: Step 1.

1. In the satellite mobile communication system, the burst data of the power control channel are uniformly distributed in k continuous traffic channels. If the quality of the current channel is to be accurately estimated, the channel quality of the k continuous traffic channel bursts needs to be averaged and corrected, so as to reduce the influence of the randomness of a single burst signal and estimate the current average signal quality ; Step 1.2, compute the prediction coefficients using the current estimate of the values and the expected prediction distance ;​ Step 1.3, calculating the channel quality prediction value for the z-th frame ; The local loop power control flow described in step 2 judges whether the receiving time of the power control channel is reached, and if the power control channel time is reached, the attenuation value of the transmitting power of the opposite end is calculated , as follows: Step 2.

1. If the power control message is decoded correctly, extract the effective transmit power of the opposite end ; If the decoding is not correct, then the last decoding that was correct is as the current transmit power; Step 2.2, The value is calculated as follows: ； Wherein, Gain is closed loop power control gain factor, SNRT is target SNR to meet certain channel error rate requirement, SNR(n) is channel quality prediction value predicted by using formula in step 1.3, n is at least current frame number plus time length consumed by one round trip, when SNRT Gain=GainDn, otherwise Gain=GainUp, GainDn and GainUp represent closed loop power control down factor and closed loop power control up factor respectively; Step 2.3, the Transcode the link attenuation value into a sideband transmitted value and fill into the sideband power control signaling to be transmitted, and wait for transmission.

2. The method of claim 1, wherein the step of determining the power level of the uplink signal comprises the steps of: determining a power level of the uplink signal; and determining a power level of the downlink signal. The satellite mobile communication system comprises GEO / LEO satellites, satellite terminals / mobile earth stations, gateway stations (GW) and operation control systems, and provides users with in-network telephone, short message, Internet access and fax services, and realizes global service interconnection through interconnection with PSTN, PLMN and Internet.

3. The adaptive power control method for a satellite mobile communication system according to claim 2, characterized in that, In the satellite mobile communication system, the burst data of the power control channel are evenly distributed in k continuous traffic channels, each channel contains a power control block, and if the current channel quality is to be accurately estimated, the channel quality of the k continuous traffic channel bursts needs to be averaged and corrected, reducing the influence of the randomness of a single burst signal to estimate the current average signal quality , as follows: Step 1.1.1, calculating the average channel quality of the nth group of traffic channels Each group of channels contains k consecutive traffic channels, constituting a power control channel. ； Step 1.1.2, calculating channel quality variance of the nth group of traffic channels : ； Step 1.1.3, if n = 1, initialize the local SNR average variance as if n > 1, update the local stored variance using the following formula, while correcting the average calculated for the current block as follows: ； The current SNR average variance is used to correct the current average signal quality: ​ ； In the formula, is a filter coefficient factor, is a correction factor, both of which are broadcast to the terminal user by the network side.

4. The method of claim 1, wherein the step of transmitting the power control command comprises the step of: transmitting the power control command to the satellite gateway in response to the received power control command. Step 1.2: Calculate the prediction coefficients using the received SNR average of N groups of on-path channels and the expected prediction distance The calculation formula is:​ ； ； wherein represents a matrix, L is a prediction coefficient matrix used the number of samples, N represents a number of samples used to obtain the in-channel power control channel SNR, represents the mth prediction coefficient matrix, m is 0 to L-1; is the mth traffic channel SNR average relative to the expected prediction distance and the prediction coefficient L, is the mth traffic channel SNR average relative to the expected prediction distance and the prediction coefficient L, is the mth traffic channel SNR average relative to the prediction coefficient L.

5. The method of claim 1, wherein the step of transmitting the power control command comprises the step of: transmitting the power control command to the satellite gateway in response to the received power control command. calculating the channel quality prediction value of the z-th frame as described in step 1.3 , the formula is: ； wherein is the average SNR of the m service channels for the relative prediction distance is the average SNR of the m service channels for the relative prediction distance 6. The method of claim 5, wherein the step of determining the power level of the uplink signal comprises the steps of: determining a power level of the uplink signal; and determining a power level of the downlink signal. calculating the attenuation value of the transmitting power of the local end by using closed loop power control as described in step 3 as follows: Step 3.

1. If the power control message is decoded correctly and the escape character is obtained, decode the the last correctly demodulated the minimum among the above, and set the step parameter Step to 0; Step 3.2, if the power control message cannot be decoded correctly or a valid escape character cannot be obtained, the last correctly demodulated As the present At the same time, the step parameter Step is set to 0.5dB; Step 3.

3. Calculate the closed loop as follows : 。 7. The method of claim 5, wherein the step of determining the power level of the uplink signal comprises the steps of: determining a power level of the uplink signal; and determining a power level of the downlink signal. Step 4: The open loop power control is used to correct the transmitting power of the current transmission at the local end The specific process is as follows: Step 4.1, predict the next frame of the control channel quality with the formula in step 1.3 The SNR obtained from the first n1 to n2 updates is averaged to obtain ; Step 4.2, calculate open loop power headroom To - ; Step 4.3, if ≥ then ； Step 4.4, if ≤ then ； wherein n1, n2, , , , are broadcast signal parameters, n1 is L-1 at the time of link prediction in step 1.3, n2 is N used at the time of link prediction in step 1.3, represents an open loop power margin, represents an open loop down power control factor, an open loop up power control factor, represents a threshold value for activating open loop power control.

8. The method of claim 1, wherein the step of transmitting the power control command comprises the step of: transmitting the power control command to the satellite gateway in response to the received power control command. The pairings described in Step 5 are subjected to clipping and quantization, as follows: clipping and quantization, as follows: According to the system set transmit power value lower limit P min and system set transmit power value upper limit P max , the local end of this transmission power amplitude limiting and quantization, according to the quantization of power settings transmission power level.

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