Satellite return channel ACM method under frequency resource limited condition

Abstract

The application discloses a satellite return channel ACM method under a frequency resource limited condition, and relates to the adaptive modulation and coding technology in the field of satellite communication. According to the signal quality of a remote station and the service application quantity, the modulation and coding mode of a return carrier is dynamically planned, and the modulation and coding mode best matched with each remote station is allocated to the remote station under the condition that the number of return carriers is small. The application fully utilizes the return carrier resource, can effectively improve the service capacity of the return channel, and improves the stability of the remote station in network operation and service transmission under a poor channel environment, and is especially suitable for small and medium-sized satellite networking application under the frequency resource limited condition.

Description

Technical Field

[0001] This invention relates to adaptive modulation and coding technology in the field of satellite communication, and is particularly suitable for satellite communication systems with limited frequency resources. Background Technology

[0002] Currently, large-scale satellite communication systems based on geostationary orbit satellites commonly use adaptive modulation and coding (ACM) technology. In favorable satellite channel conditions, higher-order modulation and coding schemes are selected to improve channel capacity, while in adverse satellite channel conditions, lower-order modulation and coding schemes are chosen to ensure stable system operation. ACM technology can adaptively select a matching modulation and coding scheme based on satellite channel quality, effectively improving carrier utilization and satellite transponder power resource utilization.

[0003] Satellite backchannel ACM control employs a centralized control method at the central station. The central station dynamically adjusts the modulation and coding scheme (ModCod) used by each remote station based on the signal quality of the transmitted signals. Currently, backchannel ACM technology typically pre-plans multiple backcarriers with different ModCods, and the central station allocates the corresponding backcarriers based on the signal quality of the remote stations. This control method works well in large-scale satellite communication systems because they have a large number of backcarriers and a rich selection of ModCods. However, small- and medium-scale satellite communication systems have fewer backcarriers and a limited ModCod selection. Using this control method in such systems may lead to a mismatch between the ModCod of a remote station and its transmitted signal quality, reducing carrier utilization and wasting satellite transponder power resources. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of ACM technology in small-to-medium-scale satellite communication systems described in the background, and to propose a satellite return channel ACM method suitable for frequency-restricted conditions. This method dynamically adjusts the return carrier ModCod according to the operating status of the satellite communication system, achieving optimal matching between the remote station's ModCod and its transmitted signal quality, thereby improving carrier utilization and avoiding waste of satellite transponder power resources.

[0005] The technical solution adopted in this invention is as follows:

[0006] A satellite return channel ACM method under frequency resource constraints, wherein the satellite return channel consists of N return carriers with the same symbol rate, includes the following steps:

[0007] (1) Configure the modulation coding types supported by the system and the access thresholds for each modulation coding type. The set of modulation coding types supported by the system is denoted as M, and the smallest modulation coding type in set M is denoted as ModCodMin.

[0008] (2) The remote station uses ModCodMin to transmit return network control signaling, which includes the remote station's service request quantity Req. rt The central station receives the return network control signaling sent by the remote station and estimates the symbol signal-to-noise ratio Es / N0 of the signal sent by the remote station. rt ;

[0009] (3) The central station periodically calculates the symbol signal-to-noise ratio Es / N0 of each remote station. rt and business application volume Req rt The mean symbol signal-to-noise ratio and the mean number of service requests within the statistical period are calculated and denoted as Es / N0, respectively. avg and Req. avg ;

[0010] (4) The central station according to Es / N0 avg Given the current modulation and coding type of the remote station and the access thresholds for each modulation and coding type within set M, calculate the desired modulation and coding type for each remote station, denoted as ModCod. exp ;

[0011] (5) Central station statistical expectation station grouping SE m , where m∈M, SE m ModCod exp Let m be the set of sites;

[0012] (6) The central station groups SEs according to the expected station for each modulation and coding type. m Generate carrier planning and determine the set M of modulation and coding types to be used for the return carrier. u and the number of carriers (CN) for each modulation and coding type. m , where m∈M u ;

[0013] (7) The central station according to M u Generation station group S m , where m∈M u S m This represents the set of remote stations using modulation and coding type m. The actual modulation and coding type used by each remote station is determined and denoted as ModCod. r ;

[0014] (8) The central station adjusts the carrier planning based on the average requested traffic volume of each site, and generates a traffic-weighted carrier quantity CN for each modulation and coding type. m ;

[0015] (9) After the central station completes the return carrier planning, it determines the effective frame;

[0016] (10) When the effective frame arrives, the central station uses the newly generated return carrier planning to calculate the return frame plan, and the station group S m The remote station allocates time slots on a carrier with modulation and coding type m, and broadcasts the return frame plan to the remote station through the forward network control time slot; at the same time, the central station plans M using the newly generated return carrier. u and CN m Configure the central station demodulator;

[0017] (11) The remote station receives the frame plan, extracts the carrier and time slot allocated to the station, and sends the station's service data to the corresponding time slot according to the modulation and coding type of the corresponding carrier.

[0018] Furthermore, the specific method of step (4) is as follows:

[0019] When the remote station's Es / N0 avg When the threshold for the modulation and coding type currently used by the remote station is greater than the threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp :

[0020] Condition 1-1, ModCod x ∈M;

[0021] Conditions 1-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements;

[0022] Conditions 1-3, ModCod x Not less than the modulation and coding type currently used by the remote station;

[0023] When the remote station's Es / N0 avg When the threshold of the modulation and coding type currently used by the remote station is less than the allowable threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp :

[0024] Condition 2-1, ModCod x ∈M;

[0025] Condition 2-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements;

[0026] Condition 2-3, ModCod x Not greater than the modulation and coding type currently used by the remote station;

[0027] When the remote station's Es / N0 avg When the threshold of the currently used modulation and coding type is greater than or equal to the threshold of the currently used modulation and coding type and less than or equal to the threshold of the currently used modulation and coding type, the currently used modulation and coding type is determined as the desired modulation and coding type (ModCod) of the remote station. exp .

[0028] Furthermore, the specific method of step (6) is as follows:

[0029] (601) Calculate the ideal number of carriers CNE for modulation and coding type m. m :

[0030] CNE m =N×card(SE) m ) / ∑ i∈M card(SE i (m∈M)

[0031] And initialize the remaining number of carriers N f and the number of carriers CN for each modulation and coding type m :

[0032] N f =N

[0033] CN m =0 (m∈M);

[0034] (602) Define CNEModCoDSt as the target modulation and coding type, and initialize CNEModCoDSt to ModCodMin;

[0035] (603) Allocate a carrier for CNEModCoDSt:

[0036] N f =N f -1

[0037] CN ModCodDst =CNE ModCodDst +1

[0038] Update the ideal number of carriers (CNE) for the target modulation and coding type. ModCodDst value:

[0039] CNE ModCodDst =CNE ModCoDSt -1(CNE ModCodDst ≥1)

[0040] CNE ModCodDst =0(CNE) ModCodDst <1)

[0041] And determine whether condition 3-1 or condition 3-2 is satisfied:

[0042] Condition 3-1, N f =0;

[0043] Condition 3-2, CNE m =0 (m∈M);

[0044] If condition 3-1 or condition 3-2 is met, proceed to step (606); otherwise, proceed to step (604).

[0045] (604) Traverse set M to find CNE m The maximum value of CNE x Assign the value x to ModCodDst and allocate a carrier to ModCodDst:

[0046] N f =N f -1

[0047] CN ModCodDst =CN ModCodDst +1

[0048] And update CNE ModCodDst Value:

[0049] CNE ModCodDst =CNE ModCodDst -1(CNE ModCodDst ≥1)

[0050] CNE ModCodDst =0(CNE) ModCodDst <1);

[0051] (605) Determine whether condition 3-1 or condition 3-2 is met. If condition 3-1 or condition 3-2 is met, execute step (606); otherwise, repeat step (604).

[0052] (606) If N f ≠0, the remaining N f Carriers are assigned to ModCodMin:

[0053] CN ModCodMin =CN ModCodMin +N f .

[0054] Furthermore, the specific method of step (8) is as follows:

[0055] (801) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type x that satisfies condition 4-1:

[0056] Condition 4-1, reducing the number of return carriers allocated to modulation and coding type x can still satisfy station group S x Business volume application;

[0057] (802) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type y that satisfies condition 4-2:

[0058] Condition 4-2, the carrier service capacity of modulation and coding type y is less than that of station group S. y Business volume application;

[0059] (803) Perform carrier allocation adjustment: CN x =CN x -1, CN y =CN y +1;

[0060] (804) Repeat steps (801), (802), and (803) until condition 4-3 or condition 4-4 is met, at which point execution terminates.

[0061] Condition 4-3: There is no modulation and coding type that satisfies condition 4-1.

[0062] Condition 4-4: There is no modulation and coding type that satisfies condition 4-2.

[0063] Compared with the prior art, the present invention has the following advantages:

[0064] 1. This invention dynamically plans the return carrier ModCod, reducing the proportion of remote stations in the network where ModCod and signal quality are mismatched;

[0065] 2. When planning the return carrier ModCod, this invention comprehensively considers the packetization of remote stations with different signal quality during system operation and the service transmission requirements of each remote station packet, which effectively improves the utilization rate of the return carrier and increases the system throughput. Attached Figure Description

[0066] Figure 1 This is a flowchart of the back channel ACM control in an embodiment of the present invention.

[0067] Figure 2 This is a schematic diagram illustrating the desired ModCod selection in an embodiment of the present invention.

[0068] Figure 3 This is a flowchart of the return carrier planning process in an embodiment of the present invention.

[0069] Figure 4This is a schematic diagram of station grouping in an embodiment of the present invention.

[0070] Figure 5 This is a flowchart of the return carrier planning and adjustment process in an embodiment of the present invention. Detailed Implementation

[0071] The invention will be further explained below with reference to the accompanying drawings.

[0072] A satellite backhaul channel ACM method under frequency resource constraints is disclosed, applicable to satellite communication systems with limited backhaul frequency resources. The satellite communication system includes a central station and remote stations. Carrier resources include one or more forward carriers and N backhaul carriers with the same symbol rate. Under conditions of limited backhaul resources, the number of backhaul carriers is generally small.

[0073] Reference Figure 1-5 The specific steps of this method are as follows:

[0074] (1) Configure the modulation and coding types (ModCod) supported by the system and the admission and admission thresholds of each ModCod. The set of ModCods supported by the system is denoted as M, and the smallest ModCod in set M is denoted as ModCodMin.

[0075] (2) The remote station uses ModCodMin to transmit return network control signaling, which includes the remote station's service request quantity Req. rt The central station receives the return network control signaling sent by the remote station and estimates the symbol signal-to-noise ratio Es / N0 of the signal sent by the remote station. rt ;

[0076] The remote station periodically sends back network control signaling to the central station via the back network control time slot. After receiving the back network control signaling, the central station can estimate the symbol signal-to-noise ratio of the signal transmitted by the remote station based on the ModCod of the network control carrier. Figure 1 As shown.

[0077] (3) The central station periodically calculates the Es / N0 of each remote station. rt and Req. rt The average symbol signal-to-noise ratio and the average number of service applications within the statistical period are calculated and denoted as Es / N0, respectively. avg and Req. avg .

[0078] (4) The central station according to Es / N0 avg Calculate the current ModCod of the remote station and the admission and access thresholds of each ModCod in set M, and denote it as ModCod. exp The specific method is as follows:

[0079] When the remote station's Es / N0avg When the threshold for the modulation and coding type currently used by the remote station is greater than the threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp :

[0080] Condition 1-1, ModCod x ∈M;

[0081] Conditions 1-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements;

[0082] Conditions 1-3, ModCod x Not less than the modulation and coding type currently used by the remote station;

[0083] When the remote station's Es / N0 avg When the threshold of the modulation and coding type currently used by the remote station is less than the allowable threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp :

[0084] Condition 2-1, ModCos x ∈M;

[0085] Condition 2-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements;

[0086] Condition 2-3, ModCos x Not greater than the modulation and coding type currently used by the remote station;

[0087] When the remote station's Es / N0 avg When the threshold of the currently used modulation and coding type is greater than or equal to the threshold of the currently used modulation and coding type and less than or equal to the threshold of the currently used modulation and coding type, the currently used modulation and coding type is determined as the desired modulation and coding type (ModCod) of the remote station. exp . Figure 2 This demonstrates the process by which the remote station expects ModCod to change dynamically.

[0088] (5) Central station statistical expectation station grouping SE m , where m∈M, SE m ModCod exp Let m be the set of sites.

[0089] (6) The central station calculates the SE of each ModCod.m Generate carrier planning and determine the set M of ModCod used for the return carrier. u And the number of carriers CN for each ModCod m , where m∈M u ;like Figure 3 As shown, the specific implementation method is as follows:

[0090] (601) Calculate the ideal number of carriers CNE for modulation and coding type m. m :

[0091] CNE m =N×card(SE) m ) / ∑ i∈M card(SE i (m∈M)

[0092] Initialize the remaining number of carriers Nf and the number of carriers CN for each modulation and coding type. m :

[0093] N f =N

[0094] CN m =0 (m∈M);

[0095] (602) Define ModCodDst as the target modulation and coding type, and initialize CNEModCoDSt to ModCodMin;

[0096] (603) Allocate a carrier for CNEModCoDSt:

[0097] N f =N f -1

[0098] CN ModCodDst =CNE ModCodDst +1

[0099] Update the ideal number of carriers (CNE) for the target modulation and coding type. ModCodDst value:

[0100] CNE ModCodDst =CNE ModCoDSt -1(CNE ModCodDst ≥1)

[0101] CNE ModCodDst =0(CNE) ModCodDst <1)

[0102] And determine whether condition 3-1 or condition 3-2 is satisfied:

[0103] Condition 3-1, N f =0;

[0104] Condition 3-2, CNE m =0 (m∈M);

[0105] If condition 3-1 or condition 3-2 is met, proceed to step (606); otherwise, proceed to step (604).

[0106] (604) Traverse set M to find CNE m The maximum value of CNE x Assign the value x to ModCodDst and allocate a carrier to ModCodDst:

[0107] N f =N f -1

[0108] CN ModCodDst =CNE ModCodDst +1

[0109] And update CNE ModCodDst Value:

[0110] CNE ModCodDst =CNE ModCoDSt -1(CNE ModCodDst ≥1)

[0111] CNE ModCodDst =0(CNE) ModCodDst <1);

[0112] (605) Determine whether condition 3-1 or condition 3-2 is met. If condition 3-1 or condition 3-2 is met, execute step (606); otherwise, repeat step (604).

[0113] (606) If N f ≠0, the remaining N f Carriers are assigned to ModCodMin:

[0114] CN ModCodMin =CN ModCodMin +N f .

[0115] (7) The central station according to M u Generation station group S m , where m∈M u S m This represents the set of remote stations using modulation and coding type m. The actual modulation and coding type used by each remote station is determined and denoted as ModCod. r Station grouping diagram as shown Figure 4 As shown.

[0116] (8) The central station adjusts the carrier planning based on the average requested traffic volume of each site, and generates a traffic-weighted carrier quantity CN for each modulation and coding type. m ;

[0117] like Figure 5 As shown, the specific implementation method is as follows:

[0118] (801) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type x that satisfies condition 4-1:

[0119] Condition 4-1, reducing the number of return carriers allocated to modulation and coding type x can still satisfy station group S x Business volume application;

[0120] (802) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type y that satisfies condition 4-2:

[0121] Condition 4-2, the carrier service capacity of modulation and coding type y is less than that of station group S. y Business volume application;

[0122] (803) Perform carrier allocation adjustment: CN x =CN x -1, CN y =CN y +1;

[0123] (804) Repeat steps (801), (802), and (803) until condition 4-3 or condition 4-4 is met, at which point execution terminates.

[0124] Condition 4-3: There is no modulation and coding type that satisfies condition 4-1.

[0125] Condition 4-4: There is no modulation and coding type that satisfies condition 4-2.

[0126] (9) After the central station completes the return carrier planning, it determines the effective frame;

[0127] After the central station completes the calculation of the return carrier planning, it generates the return carrier planning result M. u and CN m The new return carrier plan does not take effect immediately. Instead, the frame number at which the return carrier plan takes effect is determined. The system agrees to use the new return carrier plan when the effective frame arrives.

[0128] (10) When the effective frame arrives, the central station uses the newly generated return carrier planning to calculate the return frame plan, and the station group S m The remote station allocates time slots on a carrier with modulation and coding type m, and broadcasts the return frame plan to the remote station through the forward network control time slot; at the same time, the central station plans M using the newly generated return carrier. u and CN m Configure the central station demodulator.

[0129] (11) The remote station receives the frame plan, extracts the carrier and time slot allocated to the station, and sends the station's service data to the corresponding time slot according to the modulation and coding type of the corresponding carrier.

Claims

1. A satellite return channel ACM method under frequency resource constraints, wherein the satellite return channel consists of N return carriers with the same symbol rate, characterized in that, Includes the following steps: (1) Configure the modulation coding types supported by the system and the access thresholds for each modulation coding type. The set of modulation coding types supported by the system is denoted as M, and the smallest modulation coding type in set M is denoted as ModCodMin. (2) The remote station uses ModCodMin to transmit return network control signaling, which includes the remote station's service request quantity Req. rt The central station receives the return network control signaling sent by the remote station and estimates the symbol signal-to-noise ratio Es / N0 of the signal sent by the remote station. rt ; (3) The central station periodically calculates the symbol signal-to-noise ratio Es / N0 of each remote station. rt and business application volume Req rt The mean symbol signal-to-noise ratio and the mean number of service requests within the statistical period are calculated and denoted as Es / N0, respectively. avg and Req. avg ; (4) The central station according to Es / N0 avg Given the current modulation and coding type of the remote station and the access thresholds for each modulation and coding type within set M, calculate the desired modulation and coding type for each remote station, denoted as ModCod. exp ; (5) Central station statistical expectation station grouping SE m , where m∈M, SE m ModCod exp Let m be the set of sites; (6) The central station groups SEs according to the expected station for each modulation and coding type. m Generate carrier planning and determine the set M of modulation and coding types to be used for the return carrier. u and the number of carriers (CN) for each modulation and coding type. m , where m∈M u ; (7) The central station according to M u Generation station group S m , where m∈M u S m This represents the set of remote stations using modulation and coding type m. The actual modulation and coding type used by each remote station is determined and denoted as ModCod. r ; (8) The central station adjusts the carrier planning based on the average requested traffic volume of each site, and generates a traffic-weighted carrier quantity CN for each modulation and coding type. m ; (9) After the central station completes the return carrier planning, it determines the effective frame; (10) When the effective frame arrives, the central station uses the newly generated return carrier planning to calculate the return frame plan, and the station group S m The remote station allocates time slots on a carrier with modulation and coding type m, and broadcasts the return frame plan to the remote station through the forward network control time slot; at the same time, the central station plans M using the newly generated return carrier. u and CN m Configure the central station demodulator; (11) The remote station receives the frame plan, extracts the carrier and time slot allocated to the station, and sends the station's service data to the corresponding time slot according to the modulation and coding type of the corresponding carrier.

2. The satellite return channel ACM method under frequency resource constraints according to claim 1, characterized in that, The specific method for step (4) is as follows: When the remote station's Es / N0 avg When the threshold for the modulation and coding type currently used by the remote station is greater than the threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp : Condition 1-1, ModCos x ∈M; Conditions 1-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements; Conditions 1-3, ModCos x Not less than the modulation and coding type currently used by the remote station; When the remote station's Es / N0 avg When the threshold of the modulation and coding type currently used by the remote station is less than the allowable threshold, search for all ModCod modulation and coding types that meet the following conditions. x The maximum value among them is selected as the desired modulation and coding type (ModCod) for the remote station. exp : Condition 2-1, ModCod x ∈M; Condition 2-2, Es / N0 of the remote station avg Greater than ModCod x Entry requirements; Condition 2-3, ModCod x Not greater than the modulation and coding type currently used by the remote station; When the remote station's Es / N0 avg When the threshold of the currently used modulation and coding type is greater than or equal to the threshold of the currently used modulation and coding type and less than or equal to the threshold of the currently used modulation and coding type, the currently used modulation and coding type is determined as the desired modulation and coding type (ModCod) of the remote station. exp .

3. The satellite return channel ACM method under frequency resource constraints according to claim 1, characterized in that, The specific method for step (6) is as follows: (601) Calculate the ideal number of carriers CNE for modulation and coding type m. m : CNE m =N×card(SE m ) / ∑ i∈M card(SE i )(m∈M) And initialize the remaining number of carriers N f and the number of carriers CN for each modulation and coding type m : N f =N CN m =0(m∈M); (602) Define ModCodDst as the target modulation and coding type, and initialize ModCodDst to ModCodMin; (603) Allocate a carrier to ModCodDst: N f =N f -1 CN ModCodDst =CN ModCodDst +1 Update the ideal number of carriers (CNE) for the target modulation and coding type. ModCodDst value: CNE ModCodDst =CNE ModCodDst -1(CNE ModCodDst ≥1) CNE ModCodDst =0(CNE ModCodDst <1) And determine whether condition 3-1 or condition 3-2 is satisfied: Condition 3-1, N f = 0; Condition 3-2, CNE m =0 (m∈M); If condition 3-1 or condition 3-2 is met, proceed to step (606); otherwise, proceed to step (604). (604) Traverse set M to find CNE m The maximum value of CNE x Assign the value x to ModCodDst and allocate a carrier to ModCodDst: N f =N f -1 CN ModCodDst =CN ModCodDst +1 And update CNE ModCodDst Value: CNE ModCodDst =CNE ModCodDst -1(CNE ModCodDst ≥1) CNE ModCodDst =0(CNE ModCodDst <1); (605) Determine whether condition 3-1 or condition 3-2 is met. If condition 3-1 or condition 3-2 is met, execute step (606); otherwise, repeat step (604). (606) If N f ≠0, the remaining N f Carriers are assigned to ModCodMin: CN ModCodMin =CN ModCodMin +N f 。 4. The satellite return channel ACM method under frequency resource constraints according to claim 1, characterized in that, The specific method of step (8) is as follows: (801) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type x that satisfies condition 4-1: Condition 4-1, reducing the number of return carriers allocated to modulation and coding type x can still satisfy station group S x Business volume application; (802) Traverse set M u CN of various modulation and coding types m and S m Find the modulation and coding type y that satisfies condition 4-2: Condition 4-2, the carrier service capacity of modulation and coding type y is less than that of station group S. y Business volume application; (803) Perform carrier allocation adjustment: CN x =CN x -1, CN y =CN y +1; (804) Repeat steps (801), (802), and (803) until condition 4-3 or condition 4-4 is met, at which point execution terminates. Condition 4-3: There is no modulation and coding type that satisfies condition 4-1. Condition 4-4: There is no modulation and coding type that satisfies condition 4-2.

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