CN114845404B - Uplink power control method for narrow-band GEO satellite communication asymmetric channel user - Google Patents

Uplink power control method for narrow-band GEO satellite communication asymmetric channel user Download PDF

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CN114845404B
CN114845404B CN202210459589.6A CN202210459589A CN114845404B CN 114845404 B CN114845404 B CN 114845404B CN 202210459589 A CN202210459589 A CN 202210459589A CN 114845404 B CN114845404 B CN 114845404B
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satellite
user
uplink
power
channel
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CN114845404A (en
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张天桥
陈金平
刘利
章林锋
任晖
蒲俊宇
刘帅
田翌君
黄双临
王冬霞
吴杉
刘治君
沙海
王许煜
徐赟
薛峰
赵华凯
张卫楠
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32021 Army Of Chinese Pla
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/20—Control channels or signalling for resource management
    • H04W72/21—Control channels or signalling for resource management in the uplink direction of a wireless link, i.e. towards the network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0473—Wireless resource allocation based on the type of the allocated resource the resource being transmission power
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention belongs to the technical field of GEO satellite mobile communication service, and particularly relates to a narrow-band GEO satellite communication asymmetric channel user uplink power control method. The invention comprises the following steps: step 1, calculating an off-axis angle of a user position relative to a beam center under a satellite coordinate system, and estimating the downlink signal receiving power of the user under an ideal condition based on a satellite beam gain directional diagram; step 2, calculating to obtain the non-ideal attenuation condition of the downlink channel by comparing the actual downlink signal receiving power and the ideal receiving power of the user; step 3, the user terminal prepares for the open-loop precompensation of the uplink transmitting power by using the non-ideal attenuation value of the channel and the frequency compensation factor; and 4, the control section decides to carry out non-real-time closed-loop control on the user transmitting power according to actual needs. The invention reduces the same-frequency multiple access interference and improves the satellite communication uplink access capacity by optimizing the user uplink power control strategy of the weak real-time asymmetric GEO satellite narrowband communication channel.

Description

Narrow-band GEO satellite communication asymmetric channel user uplink power control method
Technical Field
The invention belongs to the technical field of GEO satellite mobile communication service, and particularly relates to a narrow-band GEO satellite communication asymmetric channel user uplink power control method.
Background
With the rapid development of global economy and technology, the demand of human beings for satellite mobile communication is more and more vigorous. Compared with ground mobile communication, the satellite mobile communication has the advantages of wide coverage area, irrelevant communication cost and distance, random access, no influence of regional disasters and the like, can cover remote areas such as oceans, deserts, airplane routes and the like, and has important functions of emergency communication and the like when ground communication facilities of the land disasters are damaged. In the field of satellite mobile communication, a user side uplink power control technology is a key link of communication channel resource adjustment and interference management. Specifically, in the field of geosynchronous orbit (GEO) satellite narrowband mobile communication service and short message service, the characteristic of weak two-way interaction real-time performance (maximum round-trip delay of 540 ms) generally exists, and meanwhile, the problems that the total throughput of downlink transmission (limited by satellite transmission EIRP) is lower than the total throughput capacity of an uplink and the like are solved.
In the fields of GEO satellite narrowband mobile communication service and short message service, the satellite-ground link realistic conditions that the uplink information transmission capacity is relatively large and the downlink information transmission capacity is small (such as Beidou short messages) are limited, and the satellite-ground link realistic conditions are that a large number of mobile users are not suitable for carrying out frequent closed loop power control signaling transmission; even when closed-loop power control is performed, the timeliness of the power control command has a great problem in applicability because of the large round-trip propagation delay. Meanwhile, satellite communication also faces the problem of imbalance of arrival power caused by channel fading fluctuation and large difference of transmitting power of user terminals in different application scenes. Uplink signals simultaneously transmitted by users in the same frequency band interfere with each other, which affects the robustness of a communication link and restricts the uplink channel transmission throughput capacity of a system.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for controlling the uplink power of the user of the narrow-band GEO satellite communication asymmetric channel reduces the same frequency multiple access interference and improves the uplink access capacity of the satellite communication by optimizing the user uplink power control strategy of the weak real-time asymmetric GEO satellite narrow-band communication channel.
The technical scheme adopted by the invention is as follows:
a method for controlling uplink power of a user with a narrow-band GEO satellite communication asymmetric channel comprises the following steps:
step 1, calculating an off-axis angle of a user position relative to a beam center under a satellite coordinate system, and estimating the downlink signal receiving power of the user under an ideal condition based on a satellite beam gain directional diagram; step 2, calculating to obtain the non-ideal attenuation condition of the downlink channel by comparing the actual downlink signal receiving power and the ideal receiving power of the user; step 3, the user terminal uses the channel non-ideal attenuation value and the frequency compensation factor to prepare for the open-loop precompensation of the uplink transmitting power; and 4, the control section decides to carry out non-real-time closed-loop control on the user transmitting power according to actual needs.
The step 1 specifically comprises the following steps:
step 1.1, a user receives a downlink signal transmitted by a certain beam B of the GEO satellite, a user terminal selects the satellite beam to access, and the user terminal obtains the satellite orbit position O (x) through a broadcast message of the GEO satellite o ,y o ,z o ) Beam B geographic center position B (x) b ,y b ,z b ) And positioning by utilizing GNSS satellite to obtain the self position U (x) of the user u ,y u ,z u ) So as to calculate the included angle UOB of the user relative to the beam center in the GEO satellite coverage area and record the included angle UOB as theta u I.e., the off-axis angle of the user with respect to the satellite beam center, the calculation formula is as follows:
Figure BDA0003620042780000021
wherein the content of the first and second substances,
Figure BDA0003620042780000022
in the formula, under the rectangular coordinate system of earth center and earth fixation,
Figure BDA0003620042780000023
is the satellite to beam center vector and,
Figure BDA0003620042780000024
a satellite-to-user vector;
the calculation formula of the elevation angle of the user observation satellite is as follows:
Figure BDA0003620042780000031
wherein, [ Delta e, [ Delta n, [ Delta u ]] T An observation vector of a satellite coordinate in a station center coordinate system with the user coordinate as an origin; [ Delta e,. DELTA.n,. DELTA.u] T And observation vectors [ delta x, delta y, delta z ] from the user to the satellite under the earth-centered earth-fixed rectangular coordinate system] T The relationship is as follows:
Figure BDA0003620042780000032
in the formula, the coordinate transformation matrix S is as follows,
Figure BDA0003620042780000033
geodetic longitude and latitude corresponding to the user position:
Figure BDA0003620042780000034
user-to-satellite observation vector [ Δ x, Δ y, Δ z] T Comprises the following steps:
Figure BDA0003620042780000035
step 1.2, calculating the theoretical downlink signal receiving carrier-to-noise ratio CNR of the user by using the satellite antenna transmission gain and the radio propagation formula ut,r_ideal ，
CNR ut,r_ideal ＝EIRP sat +G sat,t (θ u )-L dwn +G ut,r (ε)-10log(kB dwn T sat ) (6)
Wherein, EIRP sat Equivalent radiated power in the known satellite beam center direction; g sat,t (θ u ) For satellite antennas in the user direction theta u Normalized transmit gain of, L dwn For propagation loss of downstream signals in free space, G ut,r (epsilon) is the reception gain of the user terminal in the satellite direction, the reception gain of the omnidirectional antenna is recorded as 0dBi, k is Boltzmann constant, B dwn Operating the bandwidth, T, for the downlink signal sat The equivalent noise temperature of the user terminal is the user terminal;
Figure BDA0003620042780000036
Figure BDA0003620042780000041
in the above two formulae, J 1 (x) A Bessel function of the first order, a being the radius of the satellite beam circular aperture, f dwn For the downlink operating frequency, c is the speed of light, and d is the spatial distance from the satellite to the user terminal.
The step 2 specifically comprises the following steps:
step 2.1, the user terminal carries out tracking reception and channel estimation on the satellite downlink signal to obtain the actual satellite downlink signal reception carrier-to-noise ratio (CNR) ut,r_real ；
Step 2.2, calculating the non-ideal variable quantity p of the satellite downlink channel according to the difference between the actual value and the theoretical value of the downlink channel dwn And the calculation formula is as follows,
p dwn ＝CNR ut,r_real -CNR ut,r_ideal (9)。
the step 3 specifically comprises the following steps:
step 3.1, the user-satellite uplink channel has multi-gear uplink information rate according to different application scene requirements, and the gear is recorded as N (N is more than or equal to 1 and less than or equal to N); calculating the upstream sending information rate r based on the relative geometrical relation of user satellite n (N is more than or equal to 1 and less than or equal to N) minimum receiving carrier-to-noise ratio threshold CNR sat,r_ideal (r n )，
Figure BDA0003620042780000042
In the formula (I), the compound is shown in the specification,
Figure BDA0003620042780000043
for a single information bit energy to noise density ratio of
Figure BDA0003620042780000044
Error rate of time transmission, 10 -5 Is the transmission error rate threshold;
step 3.2, the spare allowance, the upper and the lower of the uplink necessary channel are consideredThe line channel compensation factor is used for calculating the information rate r of each gear n Corresponding uplink transmission power baseline P ut,t_dmd (r n )，
Figure BDA0003620042780000045
In the formula, B up Working bandwidth, T, for user uplink signals sat Receiving equivalent noise temperatures for the satellite, all known system parameters; g sat,r (θ u ) For satellite receiving antennas in the direction of the user theta u The receive gain of (a); l is up Propagation loss in free space for the uplink signal; g ut,t (epsilon) is the emission gain of the user terminal relative to the satellite direction, and the omnidirectional antenna is marked as 0dBi; alpha is an uplink and downlink channel compensation factor; g gap Margin is reserved for an uplink, and the margin is set to be 7dB;
Figure BDA0003620042780000051
Figure BDA0003620042780000052
Figure BDA0003620042780000053
selecting a message information rate matching the transmit power by equation (15): the user terminal is limited by its maximum transmitting capability P top Limiting and selecting the transmitting power P as high as possible within the range of the transmitting capability of the terminal ut,t_dmd (r n ) And an information rate r n (ii) a If the highest rate r N Corresponding transmission power requirement P ut,t_dmd (r N )≤P top Within the transmitting capability of the terminal, at the highest rate r N Transmitting; if the power requirement exceeds the terminal transmission capability P top Then the speed gear r is decreased in sequence n Until P is matched ut,t_dmd (r n )≤P top ＜P ut,t_dmd (r n+1 ) Then select the rate r n Power P ut,t_dmd (r n ) (ii) a If the speed gear is retreated to the lowest speed r 1 Yet, P t_dmd_1 ＞P top Then, it means that the uplink channel condition of the terminal does not have the access condition, and chooses not to transmit,
Figure BDA0003620042780000054
the step 4 specifically comprises the following steps:
reach carrier to noise ratio (CNR) for user terminal in control segment i Using preprocessing, using a broadband W as a sliding window to carry out smooth filtering processing, and inhibiting the estimated noise of the signal receiving equipment to the terminal power;
Figure BDA0003620042780000055
if the user terminal reaches the smooth value of the carrier-to-noise ratio for M times recently and continuously
Figure BDA0003620042780000056
Transmit power protection thresholds CNR all exceeding corresponding rates th (r n ) Then, a power control command is sent to the user terminal to indicate that the reduction amplitude of the transmission power is:
Figure BDA0003620042780000061
if the user terminal does not have the continuous power overrun behavior, the power closed-loop control is not started so as to reduce the downlink signaling of the system and save the downlink channel resources as much as possible.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
1. the invention provides a narrow-band GEO satellite communication asymmetric channel user uplink power control method, which is researched aiming at a user uplink power control method of a weak real-time (round-trip delay is about 520 ms) and asymmetric (downlink channel capacity is obviously lower than that of an uplink channel) GEO satellite narrow-band communication channel, and provides a method for combining open-loop control and intermittent closed-loop control based on user section prior information, wherein on the basis that a user section predicts a satellite multi-beam channel state, according to the receiving intensity of actual satellite downlink signals and the off-axis angle of a user terminal relative to a satellite beam center, the non-ideal attenuation (channel fading, multipath, rain fading and the like) of the downlink channel is calculated, and the uplink signal power is pre-compensated by taking the non-ideal attenuation as a base line; meanwhile, combining the self power amplification transmitting capability of the user terminal, starting to gradually retreat from the highest rate to select the uplink information rate, and completing the power control and rate matching of the open-loop uplink signal; in the control section (satellite or ground control station), based on the user uplink signal power received for many times in the appointed time window, smooth filtering and decision accumulation are carried out, and then closed-loop power control is initiated for the user.
2. The uplink power control method for the user with the asymmetric channel in the narrow-band GEO satellite communication, provided by the invention, has the advantages that the uplink transmitting power of the user terminal is effectively controlled by comprehensively utilizing the strategies based on the open-loop and intermittent closed-loop control of the prior information under the adverse conditions of large GEO round-trip delay, narrow downlink channel bandwidth and the like for diversified concurrent user transmitting rate and power requirements in an asynchronous CDMA uplink access channel, the multiple access interference of users in the same frequency band is reduced as much as possible, and the uplink access capacity of the satellite communication is effectively improved.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flowchart of a method for controlling uplink power of a user with an asymmetric channel for narrowband GEO satellite communication according to the present invention;
FIG. 2 is a schematic diagram of the two-way communication of the GEO satellite disclosed in the present invention;
FIG. 3 is a schematic view of the mutual observation geometry relationship between the GEO satellite and the user terminal disclosed by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The uplink and downlink transmission signal links of the GEO satellite are abstracted mathematically, the user side antenna is simplified into a 0dBi gain omnidirectional antenna according to the common antenna conditions of an airborne mobile communication terminal, a ship-borne mobile communication terminal and a vehicle-borne mobile communication terminal, the satellite antenna is a multi-beam parabolic antenna, and the gain of a single beam antenna is defined according to 3GPP TR 38.811 V15.1.0 (2019-06) section 6.4. As shown in fig. 1, the uplink power control method for users with asymmetric channels in narrowband GEO satellite communication provided by the present invention includes the following steps: firstly, calculating an off-axis angle of a user position relative to a beam center under a satellite coordinate system, and estimating the downlink signal receiving power of the user under an ideal condition based on a satellite beam gain directional diagram; calculating to obtain the non-ideal attenuation condition of a downlink channel by comparing the actual downlink signal receiving power and the ideal receiving power of a user; then, the user terminal prepares for the open-loop precompensation of the uplink transmitting power by utilizing the non-ideal attenuation value of the channel and the frequency compensation factor; and finally, the control section decides to carry out non-real-time closed-loop control on the user transmitting power according to actual needs.
Specifically, the user is based on the GEO satellite bidirectional communication flow, as shown in fig. 2, the user uplink power control includes the following steps:
step 1, user receiving downlink signal power estimation
Step 1.1, as shown in fig. 3, the GEO satellite continuously covers the target service area with multiple beams, the transmission/reception gains of each antenna beam in different off-axis angle directions are generally different, the user receives the downlink signal transmitted by a certain beam B of the GEO satellite, and the user terminal selects the satellite beam to access. The user terminal obtains the satellite orbit position O (x) through GEO satellite broadcast messages o ,y o ,z o ) Beam B geographic center position B (x) b ,y b ,z b ) And positioning by using GNSS satellite to obtain the user self-position U (x) u ,y u ,z u ) Therefore, an included angle UOB of the user relative to the beam center in the GEO satellite coverage area is calculated and recorded as theta u I.e., the off-axis angle of the user with respect to the satellite beam center, the calculation formula is as follows:
Figure BDA0003620042780000081
wherein the content of the first and second substances,
Figure BDA0003620042780000082
in the formula, under the rectangular coordinate system of earth center and earth fixation,
Figure BDA0003620042780000083
is the satellite to beam center vector and,
Figure BDA0003620042780000084
a satellite-to-user vector; o (x) o ,y o ,z o ) For communication of satellite orbital position, B (x) b ,y b ,z b ) Obtaining a beam geographic center position through a satellite downlink broadcast message; u (x) u ,y u ,z u ) The position of the user is obtained through GNSS positioning calculation.
The calculation formula of the elevation angle of the user observation satellite is as follows:
Figure BDA0003620042780000085
wherein, [ Delta e, [ Delta n, [ Delta u ]] T An observation vector of a satellite coordinate in a station center coordinate system with the user coordinate as an origin; [ Delta e,. DELTA.n,. DELTA.u] T Observation vector [ delta x, delta y, delta z from user to satellite under rectangular coordinate system with earth center and earth fixed] T The relationship is as follows:
Figure BDA0003620042780000091
in the formula, the coordinate transformation matrix S is as follows,
Figure BDA0003620042780000092
geodetic longitude and latitude corresponding to the user position:
Figure BDA0003620042780000093
user-to-satellite observation vector [ Δ x, Δ y, Δ z] T Comprises the following steps:
Figure BDA0003620042780000094
step 1.2, calculating the theoretical downlink signal receiving carrier-to-noise ratio CNR of the user by using the satellite antenna transmission gain and the radio propagation formula ut,r_ideal ，
CNR ut,r_ideal ＝EIRP sat +G sat,t (θ u )-L dwn +G ut,r (ε)-10log(kB dwn T sat ) (6)
Wherein, EIRP sat Equivalent radiated power in the known satellite beam center direction; g sat,t (θ u ) For satellite antennas in the user direction theta u Normalized transmission gain of, L dwn For propagation loss of downstream signals in free space, G ut,r (ε) is the reception gain of the user terminal in the satellite direction, the reception gain of the omnidirectional antenna is recorded as 0dBi, k is Boltzmann constant, B dwn Operating the bandwidth, T, for the downlink signal sat The equivalent noise temperature of the user terminal itself.
Figure BDA0003620042780000095
Figure BDA0003620042780000096
In the above two formulae, J 1 (x) Bessel function of the first order, a being the radius of the satellite beam circular aperture, f dwn For the downlink operating frequency, c is the speed of light, and d is the spatial distance from the satellite to the user terminal.
Step 2, evaluating the nonideal attenuation of the downlink propagation link
Step 2.1, the user terminal carries out tracking reception and channel estimation on the satellite downlink signal to obtain the actual receiving carrier-to-noise ratio strength CNR of the satellite downlink signal ut,r_real 。
Step 2.2, calculating the nonideal satellite downlink channel through the difference between the actual value and the theoretical value of the downlink channelAmount of change p dwn The calculation formula is as follows, and the influencing factors mainly include channel fading, multipath, rain attenuation and the like.
p dwn ＝CNR ut,r_real -CNR ut,r_ideal (9)
This value may also appear to be positive due to bias in the satellite antenna gain model.
Step 3, open loop precompensation of user uplink transmitting power:
step 3.1, the user-satellite uplink channel generally has multi-gear uplink information rate according to different application scene requirements, and the gear is marked as N (N is more than or equal to 1 and less than or equal to N); calculating the upstream sending information rate r based on the relative geometrical relation of user satellite n (N is more than or equal to 1 and less than or equal to N) minimum receiving carrier-to-noise ratio threshold CNR sat,r_ideal (r n )。
Figure BDA0003620042780000101
In the formula (I), the compound is shown in the specification,
Figure BDA0003620042780000102
for a single information bit energy to noise density ratio of
Figure BDA0003620042780000103
Error rate of time transmission, 10 -5 Is a transmission error rate threshold; for example, by looking up the ber curve of the specified modulation scheme, BPSK modulation is performed under the additive high-speed white noise condition 10 -5 Corresponding to threshold of bit error rate
Figure BDA0003620042780000104
The requirement is 9.6dB; g FEC Gain is encoded for the forward error correction channel.
Step 3.2, the necessary channel margin of the uplink and the compensation factor of the uplink and the downlink are considered, and the information rate r of each gear is calculated n Corresponding uplink transmission power baseline P ut,t_dmd (r n )。
Figure BDA0003620042780000105
In the formula, B up Working bandwidth, T, for user uplink signals sat Receiving equivalent noise temperatures for the satellite, all known system parameters; g sat,r (θ u ) For satellite receiving antennas in the direction of the user theta u The receive gain of (a); l is up Propagation loss in free space for the uplink signal; g ut,t (epsilon) is the emission gain of the user terminal relative to the satellite direction, and the omnidirectional antenna is marked as 0dBi; alpha is an uplink and downlink channel compensation factor; g gap The margin is typically set to 7dB for the uplink.
Figure BDA0003620042780000111
Figure BDA0003620042780000112
Figure BDA0003620042780000113
And (3) transmission rate matching: the user terminal is limited by its maximum transmitting capability P top Limiting, selecting the transmitting power P as high as possible within the range of the transmitting capability of the terminal ut,t_dmd (r n ) And an information rate r n . If the highest rate r N Corresponding transmission power requirement P ut,t_dmd (r N )≤P top Within the transmitting capability of the terminal, at the highest rate r N Transmitting; if the power requirement exceeds the terminal transmission capability P top Then sequentially decrease the speed gear r n Until P is matched ut,t_dmd (r n )≤P top ＜P ut,t_dmd (r n+1 ) Then select the rate r n Power P ut,t_dmd (r n ) (ii) a If the speed gear is retreated to the lowest speed r 1 Is still P t_dmd_1 ＞P top Then, it indicates the terminal uplink messageAnd selecting not to transmit if the channel condition does not have the access condition.
Figure BDA0003620042780000114
Step 4, the control section carries out closed-loop control on the user transmitting power:
arrival carrier-to-noise ratio (CNR) for user terminals in the control section (ground central station or processing satellite) i Using preprocessing, performing smooth filtering processing by using a broadband W as a sliding window, and suppressing the estimation noise of the signal receiving equipment to the terminal power;
Figure BDA0003620042780000115
if the user terminal reaches the smooth value of the carrier-to-noise ratio for M times recently and continuously
Figure BDA0003620042780000116
Transmission power protection threshold CNR of all exceeding corresponding speed th (r n ) Then sending power control command to user terminal to indicate the reduction of transmitting power to
Figure BDA0003620042780000121
If the user terminal does not have the continuous power overrun behavior, the power closed-loop control is not started so as to reduce the downlink signaling of the system and save the downlink channel resources as much as possible.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (1)

1. A narrow-band GEO satellite communication asymmetric channel user uplink power control method is characterized in that: the method comprises the following steps: step (1), calculating an off-axis angle of a user position relative to a beam center under a satellite coordinate system, and estimating the downlink signal receiving power of the user under an ideal condition based on a satellite beam gain directional diagram; step (2), calculating to obtain a non-ideal attenuation value of a downlink channel by comparing the actual downlink signal receiving power of a user with the downlink signal receiving power of the user under an ideal condition; step (3), the user terminal utilizes the non-ideal attenuation value and the frequency compensation factor of the downlink channel to prepare for open loop precompensation of uplink transmitting power; step (4), the control section decides to carry out non-real-time closed-loop control on the user transmitting power according to actual needs;
the step (1) specifically comprises the following steps:
step (1.1), the user receives the downlink signal transmitted by a certain beam B of the GEO satellite, the user terminal selects the satellite beam to access, and the user terminal obtains the satellite orbit position O (x) through the broadcast message of the GEO satellite o ,y o ,z o ) Beam B geographic center position B (x) b ,y b ,z b ) And positioning by utilizing GNSS satellite to obtain the self position U (x) of the user u ,y u ,z u ) Therefore, an included angle UOB of the user relative to the beam center in the GEO satellite coverage area is calculated and recorded as theta u I.e., the off-axis angle of the user with respect to the satellite beam center, the calculation formula is as follows:
Figure FDA0003814442960000011
wherein the content of the first and second substances,
Figure FDA0003814442960000012
in the formula, under the rectangular coordinate system of earth center and earth fixation,
Figure FDA0003814442960000013
is the satellite to beam center vector and,
Figure FDA0003814442960000014
a satellite-to-user vector;
the elevation angle calculation formula of the user observation satellite is as follows:
Figure FDA0003814442960000021
wherein, [ Delta e, [ Delta n, [ Delta u ]] Τ An observation vector of a satellite coordinate in a station center coordinate system with the user coordinate as an origin; [ Delta e,. DELTA.n,. DELTA.u] Τ Observation vector [ delta x, delta y, delta z from user to satellite under rectangular coordinate system with earth center and earth fixed] Τ The relationship is as follows:
Figure FDA0003814442960000022
in the formula, the coordinate transformation matrix S is as follows,
Figure FDA0003814442960000023
geodetic longitude and latitude corresponding to the user position:
Figure FDA0003814442960000024
user to satellite observation vector [ Δ x, Δ y，Δz] Τ Comprises the following steps:
Figure FDA0003814442960000025
step (1.2), calculating the theoretical downlink signal receiving carrier-to-noise ratio (CNR) of the user by using the satellite antenna transmission gain and the radio propagation formula ut,r_ideal ，
CNR ut,r_ideal ＝EIRP sat +G sat,t (θ u )-L dwn +G ut,r (ε)-10log(kB dwn T sat ) (6)
Wherein, EIRP sat The equivalent radiated power in the known satellite beam center direction; g sat,t (θ u ) For satellite antenna in user direction theta u Normalized transmit gain of, L dwn For propagation loss of downstream signals in free space, G ut,r (ε) is the reception gain of the user terminal in the satellite direction, the reception gain of the omnidirectional antenna is recorded as 0dBi, k is Boltzmann constant, B dwn Working the bandwidth, T, for the downstream signal sat The equivalent noise temperature of the user terminal is the user terminal;
Figure FDA0003814442960000031
Figure FDA0003814442960000032
in the above two formulae, J 1 (x) A Bessel function of the first order, a being the radius of the satellite beam circular aperture, f dwn Is the downlink working frequency, c is the speed of light, d is the spatial distance from the satellite to the user terminal;
the step (2) specifically comprises the following steps:
step (2.1), the user terminal tracks and receives the satellite downlink signal and estimates the channel to obtain the actual satellite downlink signal receiving carrier-to-noise ratio intensity CNR ut,r_real ；
Step (2.2), calculating the non-ideal variable quantity p of the satellite downlink channel according to the difference between the actual value and the theoretical value of the downlink channel dwn The calculation formula is as follows,
p dwn ＝CNR ut,r_real -CNR ut,r_ideal (9)；
the step (3) specifically comprises the following steps:
step (3.1), the user-satellite uplink channel has multi-gear uplink information rate according to different application scene requirements, and the gear is recorded as N (N is more than or equal to 1 and less than or equal to N); calculating the upstream sending information rate r based on the relative geometrical relation of user satellite n (N is more than or equal to 1 and less than or equal to N) minimum receiving carrier-to-noise ratio threshold CNR sat,r_ideal (r n )，
Figure FDA0003814442960000033
In the formula (I), the compound is shown in the specification,
Figure FDA0003814442960000034
for a single information bit energy to noise density ratio of
Figure FDA0003814442960000035
Transmission error rate of time, 10 -5 For transmission of threshold of error rate, G FEC Coding gain for a forward error correction channel;
step (3.2), the necessary channel margin of the uplink and the compensation factor of the uplink and the downlink are considered, and the information rate r of each gear is calculated n Corresponding uplink transmission power baseline P ut,t_dmd (r n )，
Figure FDA0003814442960000041
In the formula, B up Working bandwidth, T, for user uplink signals sat Receiving equivalent noise temperatures for the satellite, all known system parameters; g sat,r (θ u ) For satellite receiving antennas in the direction of the user theta u The receive gain of (a); l is up Propagation loss in free space for the uplink signal; g ut,t (epsilon) is the transmission gain of the user terminal relative to the satellite direction, and the omnidirectional antenna is marked as 0dBi; alpha is an uplink and downlink channel compensation factor; g gap Margin is reserved for an uplink, and the margin is set to be 7dB;
Figure FDA0003814442960000042
Figure FDA0003814442960000043
Figure FDA0003814442960000044
wherein: f. of up Is an uplink operating frequency;
selecting a message information rate matching the transmit power by equation (15): the user terminal is limited by its maximum transmitting capability P top Limiting and selecting the transmitting power P as high as possible within the range of the transmitting capability of the terminal ut,t_dmd (r n ) And an information rate r n (ii) a If the highest rate r N Corresponding transmission power requirement P ut,t_dmd (r N )≤P top Within the transmitting capability of the terminal, at the highest rate r N Transmitting; if the power requirement exceeds the terminal transmission capability P top Then the speed gear r is decreased in sequence n Until P is matched ut,t_dmd (r n )≤P top ＜P ut,t_dmd (r n+1 ) Then select the rate r n Power P ut,t_dmd (r n ) (ii) a If the speed gear is retreated to the lowest speed r 1 Is still P t_dmd_1 ＞P top Then, it means that the uplink channel condition of the terminal does not have the access condition, and chooses not to transmit,
Figure FDA0003814442960000051
the step (4) specifically comprises the following steps:
reach carrier to noise ratio (CNR) for user terminal in control segment i Using preprocessing, using a broadband W as a sliding window to carry out smooth filtering processing, and inhibiting the estimated noise of the signal receiving equipment to the terminal power;
Figure FDA0003814442960000052
if the user terminal reaches the smooth value of the carrier-to-noise ratio for M times recently and continuously
Figure FDA0003814442960000053
Transmission power protection threshold CNR of all exceeding corresponding speed th (r n ) Then, a power control command is sent to the user terminal to indicate that the reduction amplitude of the transmission power is:
Figure FDA0003814442960000054
if the user terminal does not have the continuous power overrun behavior, the power closed-loop control is not started so as to reduce the downlink signaling of the system and save the downlink channel resources as much as possible.
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