Satellite network transmission protocol timer adaptive adjustment method

Abstract

The application discloses a kind of satellite network transmission protocol timer adaptive adjustment method.For the problem that ACK feedback is extremely sparse in satellite network, leading to the difficulty of end-to-end delay estimation and timely convergence, the application obtains the delay cycle table of transmission path between any source-destination node pair based on the periodic topology link planning of satellite network, and maintains it locally in each node.During the connection establishment and operation of the transmission protocol, the transmission path delay of the current time window is obtained by searching the table in real time, and this is used as a reference to configure the time class timing parameters of the satellite network transmission protocol, and it is adaptively reconfigured when the delay cycle switches.The application makes the timer parameters of the transmission protocol consistent with the actual link, eliminates false timeout judgment and redundant retransmission, and improves the link utilization efficiency and end-to-end transmission performance.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, and in particular relates to an adaptive adjustment method for a satellite network transmission protocol timer. Background Technology

[0002] In satellite networks, transmission protocols typically rely on time-based timing parameters for reliable transmission and retransmission control, and these timer parameters are often closely related to end-to-end latency. In engineering implementation, Quick UDP Internet Connections (QUIC) based on the User Datagram Protocol (UDP) have become an important technical direction and can be used as a representative implementation of satellite network transmission protocols. The core of the QUIC protocol's acknowledgment and retransmission mechanism relies on the acknowledgment (ACK) messages returned by the receiver to estimate the end-to-end latency, and then sets time-related retransmission timer parameters such as packet loss time thresholds and probe timeouts (PTOs) based on this.

[0003] Specifically, QUIC's ACK-based packet loss detection mainly includes two mechanisms: First, time-threshold-based packet loss detection. When an unacknowledged data packet has been sent for more than the specified time threshold without being acknowledged, the data packet is considered lost. The time threshold parameter directly depends on the end-to-end latency estimation. Second, packet number-threshold-based packet loss detection. When the packet number of a data packet lags behind the acknowledged packet number by more than a preset packet number threshold, the data packet is considered lost. This mechanism's determination does not directly depend on the end-to-end latency estimation. Both of these packet loss detection mechanisms typically rely on the premise that a subsequent data packet with a larger packet number has been acknowledged. If no subsequent data packet with a larger packet number is acknowledged after the data packet awaiting acknowledgment, neither the packet number-threshold-based nor the time-threshold-based packet loss detection will be triggered in time. Therefore, QUIC sets up a Probe Timeout (PTO) mechanism to trigger the sending of a probe message when the acknowledgment progress stalls and no ACK is received for an extended period, prompting the peer to generate and return an ACK, providing the necessary acknowledgment progress conditions for subsequent packet loss determination. Therefore, in cases of sparse ACKs and tail packet loss, the triggering of the above packet loss detection mechanism depends on PTO, and the calculation of PTO is also based on end-to-end latency estimation.

[0004] However, influenced by factors such as orbital motion, celestial obstruction, and ground station visibility windows, the link between the source and destination exhibits intermittent connectivity, leading to significant fluctuations in round-trip time (RTT). In deep space environments, signal propagation delays on deep space links such as Earth-Mars can reach several minutes or even tens of minutes, resulting in substantial RTTs. Acknowledgment (ACK) feedback is often extremely sparse or even unavailable for extended periods, making it difficult for end-to-end delay estimations based primarily on ACKs to converge in a timely manner. The packet loss time threshold and PTO configuration are severely mismatched with the actual link delay, easily leading to frequent erroneous packet loss assessments and redundant retransmissions. This further triggers unnecessary probe message transmission and retransmission overhead, consuming limited deep space link resources and significantly reducing link utilization. These problems are not unique to QUIC but are also prevalent in satellite network transmission protocols that use acknowledgment feedback to drive time parameter updates.

[0005] Meanwhile, satellite networks possess strong orbital dynamics and periodic characteristics, as well as mission planning and scheduling capabilities, enabling the formation of periodic topological connections between any two points on the network. Based on these periodic topological connections, the transmission path delay and corresponding effective time range between any source-destination pair can be derived under a given data injection time. One technique for characterizing and utilizing this periodic topological connection is Contact Graph Routing (CGR). The CGR algorithm models the connection relationships between nodes at different times as a time-varying graph and completes link planning under a preset data injection time, obtaining the path strategy and delay parameters between any source-destination pair. Existing CGR methods primarily use the delay information for path strategy and forwarding decisions, but the configuration and updating of time-related parameters of the transmission protocol typically lack a coordination mechanism with the link planning results. Therefore, it is necessary to utilize the transmission path delay obtained from link planning to adjust the time-related timing parameters of the satellite network transmission protocol, and adaptively reconfigure them during the updating and switching of corresponding entries in the delay periodicity table, thereby improving the transmission efficiency of the satellite network transmission protocol. Summary of the Invention

[0006] Objective: To address the problems of existing transmission protocols applied to satellite networks, such as the inability to converge end-to-end delay estimation in a timely manner, and the severe mismatch between time threshold-based packet loss detection conditions and probe timeout timing parameters and actual link delays, which easily leads to incorrect timeout determinations, over-probing, and redundant retransmissions, this invention discloses an adaptive adjustment method for timers in satellite network transmission protocols. This invention obtains the transmission path delay based on the periodic topology of the satellite network and, based on this, configures and adaptively updates the time-related timing parameters in the satellite network transmission protocol, improving link utilization efficiency and end-to-end transmission performance.

[0007] The above objectives are achieved through the following technical solutions:

[0008] The satellite network transmission protocol timer adaptive adjustment method of the present invention obtains a delay period table of the transmission path between any source and destination node pairs based on the periodic topology link planning of the satellite network, and maintains it locally on each node. During connection establishment and operation, the transmission protocol looks up the table in real time to obtain the transmission path delay of the current time window, and uses this as a benchmark to configure the time-type timing parameters of the satellite network transmission protocol, and adaptively reconfigures them when the delay period changes.

[0009] Furthermore, the method specifically includes the following steps:

[0010] S1. Based on the pre-generated periodic topology connection relationship of the satellite network, establish a time-varying diagram of the connection relationship, perform link planning, obtain the transmission path delay from the current node to different destination nodes in different time intervals, and form a delay periodic table based on time-period connections; when there are multiple candidate entries that simultaneously meet the valid time range, the entry with the smallest transmission path delay is selected as the current active entry.

[0011] S2. Store and maintain the time-based connection delay period table in each node, enabling the transmission protocol to be based on the destination node address. and the current system time Real-time lookup of transmission path latency for the current time window ;

[0012] S3. During connection establishment and operation, the transport layer uses the read transmission path delay value as a reference to adjust the timing parameters of the satellite network transmission protocol:

[0013] Round trip delay Directly adopt Configure the initial round-trip time using the following formula:

[0014] ;

[0015] Packet loss timer Combined with system resolution and magnification factor The calculation is performed using the following formula:

[0016] ;

[0017] Detection timer Introducing a safety factor To suppress overprobeing, the formula is:

[0018] ;

[0019] S4. When the current system time... When the effective time range is exceeded, causing a change in the delay periodicity table entry, or when the acknowledgment message is detected to be advancing its acknowledgment progress, the transmission protocol automatically triggers the reconfiguration of timer parameters and the reset of the probe timer backoff state, so that it is recalculated based on the current transmission path delay. Run at the baseline value.

[0020] Furthermore, the time delay periodic table based on time-period connections in step S1 includes the following fields:

[0021] Start Time: Indicates the effective start time of the transmission path corresponding to the transmission path delay;

[0022] End time: Indicates the effective end time of the transmission path corresponding to the transmission path delay;

[0023] Destination node: Represents the address of the destination node;

[0024] Transmission path delay: Represents the transmission path delay from the current node to the destination node calculated by link planning.

[0025] Furthermore, the generation method of the time-delay periodic table based on time-period connections includes, but is not limited to, the following two:

[0026] 1) The results are calculated uniformly by either the ground mission planning and network management system and uploaded to each node;

[0027] 2) Calculated by the on-board node and generated locally on the node.

[0028] Beneficial effects: This invention provides an adaptive adjustment method for timers in satellite network transmission protocols. It uses the transmission path delay obtained from link planning as the benchmark for time-based timing control of satellite network transmission protocols, adjusts the time-based timing parameters of satellite network transmission protocols, and adaptively reconfigures them when the delay period switches. This avoids the timing parameter configuration mismatch problem caused by the existing satellite network transmission protocols relying on ACK samples for passive end-to-end delay estimation, reduces the probability of erroneous judgment timeouts, over-probing, and redundant retransmissions, and improves link utilization efficiency and end-to-end transmission performance. Attached Figure Description

[0029] Figure 1 A schematic diagram of the overall process for the adaptive adjustment method of satellite network transmission protocol timers;

[0030] Figure 2 This is a structural diagram of a time-delay periodic table based on time-period connections;

[0031] Figure 3 This is a schematic diagram of the deep space network topology and configuration. Detailed Implementation

[0032] The invention will be further described below with reference to the accompanying drawings and specific application scenarios.

[0033] Existing satellite network transmission protocols typically maintain state parameters related to time-based timing control, such as round-trip time, packet loss timers, and probe timers, providing a basic timescale for connection establishment, reliable transmission, and timing control. In typical terrestrial internet application scenarios, during connection initialization and the lack of ACK samples, the sending end sets the aforementioned timescale based on a preset end-to-end delay; during connection operation, the sending end relies on ACK feedback from the receiving end to obtain the actual end-to-end delay and updates the timescale accordingly. This framework is essentially based on the assumptions of continuous end-to-end path connectivity, low end-to-end delay, and the ability to obtain sufficient ACK samples within a short timescale in terrestrial internet, thus forming a timescale suitable for timing control.

[0034] For ease of explanation, the following uses QUIC, a UDP-based transport protocol implementation, as an example to illustrate the adaptation problem of acknowledgment feedback-driven time parameter adjustment in satellite networks and the improvement method of this invention. QUIC's time-threshold-based packet loss detection triggers packet loss determination and retransmission when unacknowledged data packets have been sent for more than the specified time threshold without being acknowledged. The time threshold parameter setting directly depends on the end-to-end delay estimation. Furthermore, QUIC uses a probe timeout to trigger the sending of probe messages when no ACK is received for an extended period, prompting the peer to generate an ACK feedback. The PTO calculation is also based on the end-to-end delay estimation. Both the time-threshold-based packet loss detection and the probe timeout mechanism rely on a time scale that reflects the end-to-end path delay.

[0035] In satellite network environments, ACK feedback is often extremely sparse or even unavailable for extended periods. This makes it difficult to rely solely on the timescale of ACK samples for acquisition and updates. The configuration of packet loss time thresholds and PTOs is severely mismatched with actual link latency, easily leading to frequent erroneous packet loss and redundant retransmissions, and triggering unnecessary probe message transmissions, significantly reducing deep space link utilization. Since the connection window and available bandwidth of satellite network links are strictly constrained, the aforementioned redundancy control behaviors will further encroach on limited transmission resources, resulting in decreased link utilization and degraded end-to-end transmission performance.

[0036] To address the aforementioned issues, this invention proposes an adaptive adjustment method for satellite network transmission protocol timers. The core idea is as follows: based on a pre-generated periodic topology of the satellite network, a time-varying graph of connection relationships is established. Link planning is performed to obtain the transmission path delay and its effective time range between any source and destination node pairs, forming a delay periodic table based on time-period connections, which is maintained locally at each node. During connection establishment and operation, the transmission protocol looks up the delay periodic table based on the destination node address to obtain the transmission path delay for the current time window. The timing parameters of the satellite network transmission protocol are configured using this transmission path delay as a benchmark, and adaptive reconfiguration is performed during delay periodic table updates and switching.

[0037] This invention does not rely on passively converging end-to-end delay through ACK samples to form a time scale, which enables the timing parameters of the transmission protocol to be consistent with the actual link, eliminates error timeout judgment and redundant retransmission, and improves link utilization efficiency and end-to-end transmission performance.

[0038] Specifically, the satellite network transmission protocol timer adaptive adjustment method of the present invention includes:

[0039] 1. Obtain the transmission path delay between any pair of nodes based on link planning.

[0040] The periodic topology connections of a satellite network can be pre-generated by the mission planning system based on information such as spacecraft orbit, attitude, and ground station visibility windows. After parsing the periodic topology connections of the satellite network, the CGR algorithm constructs a time-varying graph of the connections based on fields such as sending node identifier, receiving node identifier, connection start time, connection end time, link propagation delay, and available bandwidth. Under preset data injection time conditions, it completes link planning, obtains the transmission path delay from the current node to different destination nodes and their corresponding effective time range, and forms a time delay periodic table based on time-period connections.

[0041] The time-based connection delay periodic table exists in each node. Each node maintains a time-based delay periodic table from its own source to different destination nodes, which stores the transmission path delay and its effective time range from the current node to different destination nodes.

[0042] like Figure 2 As shown, the time-delay periodic table based on time-period connections includes the following fields:

[0043] Start Time: Indicates the effective start time of the transmission path corresponding to the transmission path delay;

[0044] End time: Indicates the effective end time of the transmission path corresponding to the transmission path delay;

[0045] Destination node: Represents the address of the destination node;

[0046] Transmission path delay: Represents the transmission path delay from the current node to the destination node calculated by link planning.

[0047] The generation methods for time-delay periodic tables based on time-period connections include, but are not limited to, the following two:

[0048] 1) The results are calculated uniformly by either the ground mission planning and network management system and uploaded to each node;

[0049] 2) Calculated by the on-board node and generated locally on the node.

[0050] The start and end times are used to define the applicable range of transmission path delay. When searching the delay periodic table based on time-based connections, the transmission protocol selects the entry that matches the current time. The start and end times use the same time base as the current time to ensure consistency in entry matching. When multiple candidate entries simultaneously meet the valid time range, the entry with the smallest transmission path delay is selected as the current entry. The delay periodic table based on time-based connections can be refreshed and replaced as the satellite network's periodic topology connections are updated.

[0051] 2. Adaptively adjust the timing parameters of the satellite network transmission protocol based on the time delay periodic table.

[0052] Based on the aforementioned delay periodicity table, this invention performs a lookup at the transport layer side based on the destination node address and the current time, reads the entry matching the current time, obtains the corresponding transmission path delay, and uses this transmission path delay as a unified time scale for the time-based timing control of the satellite network transmission protocol. This allows the time-based timing parameters of the satellite network transmission protocol to be adaptively reconfigured during updates and switches of the entries, resulting in timing parameters consistent with the actual link. The destination node address and the current time are denoted as... , The transport layer obtains the transmission path delay from the delay periodicity table, denoted as... .

[0053] This invention no longer uses ACK sample-driven passive estimation as the source of the time scale, but directly adopts... As the transmission path delay of the connection at the current moment, when using QUIC as an example implementation, this delay value can be used to configure the round-trip delay of QUIC. The round-trip delay parameter is denoted as... This allows the system to obtain timing parameters consistent with the actual link during the connection establishment phase, and to adjust synchronously when the corresponding entries in the delay period table are updated or switched.

[0054] ;

[0055] In particular, in deep space network environments, transmission path delay is primarily determined by propagation delay and waiting delay introduced by the connection window, and typically exhibits segmented stability and predictable, time-segmented switching characteristics. direct as The configuration basis can avoid the risks of timescale drift and long-term mismatch caused by using a fixed initial delay and relying on sparse ACK samples.

[0056] In terms of packet loss detection based on time thresholds, this invention also uses... As a benchmark, and with a minimum granularity lower bound set, error timeout judgments and redundant retransmissions are avoided, forming a time threshold that matches the transmission path delay. The packet loss timer duration is denoted as... A preferred calculation formula is as follows:

[0057] ;

[0058] in, It is usually determined by the system clock resolution and the timer implementation method. This is an amplification factor used to balance the probability of misjudgment with the speed of recovery triggering. Smaller values ​​will trigger packet loss recovery faster, but are more prone to false positives. A larger value will suppress false positives, but will delay the triggering of packet loss recovery.

[0059] Regarding the configuration of the probe timer, this invention uses... As a benchmark, and introduce coefficients Provides necessary safety margins to suppress excessive probing and additional overhead caused by latency fluctuations or ACK sparsity. The probe timer duration is denoted as... A preferred calculation formula is as follows:

[0060] ;

[0061] in, This is the safety factor. The value of reflects a trade-off between detection timeliness and detection overhead suppression: Smaller sizes can trigger detection faster but are prone to over-probing. A larger PTO can suppress probing but may prolong the recovery trigger time. If necessary, to suppress excessive probing under conditions of prolonged stagnation in the confirmation progress, the PTO can also increase according to a preset backoff rule. For example, a multiplicative backoff: when no progress in the confirmation status is observed after several consecutive PTO triggers, the current PTO is increased by a preset multiplier. This multiplier can be 2, or other constants greater than 1, and a maximum upper limit can be set to avoid unbounded growth. When the time delay periodic table is updated or switched, or when progress in the confirmation status occurs, the PTO reverts to a new PTO based on the new... The recalculated baseline value.

[0062] Through the above configuration, this invention abandons estimating transmission path delay using ACK samples, and instead directly uses the transmission path delay from the delay periodicity table as the time scale source. Therefore, when QUIC is used as an example implementation, QUIC's time-based timing control can directly obtain a stable time scale that can switch according to time intervals, thus improving the existing QUIC methods for characterizing the lower bound and fluctuation amplitude of end-to-end delay. and In the context of this invention, the parameters can be weakened, simplifying parameter maintenance and calculation, while avoiding the risk of unstable estimation and timer mismatch due to insufficient samples under ACK sparsity conditions.

[0063] When the current time spans into a new valid time range, or when the time delay periodicity table is refreshed or replaced due to periodic updates to the satellite network topology, the transport layer re-searches for and obtains the new time delay periodicity table. And update accordingly. , , Equal-time timing control parameters enable the retransmission timing control of the connection to continuously track the link planning results, reduce the probability of erroneous timeouts, overprobing, and redundant retransmissions, and improve link utilization efficiency and end-to-end transmission performance.

[0064] A specific application scenario is described below.

[0065] Based on the existing Internet architecture, this invention obtains a time delay period table for the transmission path between any source and destination node pairs by planning the periodic topology links of the satellite network. Based on this, the timing parameters of the satellite network transmission protocol are adjusted, and adaptive reconfiguration is performed when the time delay period switches. This invention can be applied to deep space networks, hybrid networks of Geostationary Earth Orbit (GEO), Medium Earth Orbit (MEO), and Low Earth Orbit (LEO) satellites, mobile vehicular networks, as well as intermittent communication networks and self-organizing networks.

[0066] One practical application scenario of this invention is deep space network data transmission. To illustrate how this invention is used in a real network, the deep space network data transmission scenario is abstracted into a four-node topology, as shown in the attached figure. Figure 3 As shown, it includes a deep-space terminal, a deep-space relay satellite, a ground station, and a ground server. QUIC is selected as the example transmission protocol in the specific implementation. Both the deep-space terminal and the ground server deploy the QUIC protocol and the CGR algorithm; the specific internal interaction flow is shown in the appendix. Figure 1 As shown.

[0067] The IPv6 address of the deep space terminal is configured as 2001:DB8:100:1::10 / 64, and the IPv6 address of the ground server is configured as 2001:DB8:400:1::40 / 64.

[0068] (1) Generation of a time-delay periodic table based on time-period connections

[0069] In this application scenario, the mission planning system generates a periodic topology connection relationship of the satellite network covering a future period based on information such as spacecraft orbit, attitude, and ground station visibility window. The CGR algorithm parses the periodic topology connection relationship, establishes a time-varying graph of the connection relationship, and performs link planning to obtain the transmission path delay from the current node to different destination nodes and their corresponding start and end times. A time-based connection delay periodic table is formed and maintained locally on the node. Taking the Deep Space Terminal as an example, the time-based connection delay periodic table maintained locally by the Deep Space Terminal is listed in Table 1. The units of start time, end time, and transmission path delay are all seconds. For ease of explanation, the reference time in this example is... The start and end times in the table are expressed in relative seconds from the reference time. In engineering implementation, a unified time base consistent with the node system clock can also be used.

[0070] Table 1. Latency Period Table for Deep Space Terminal Based on Time-Based Connections

[0071] Start time End time destination node End-to-end delay value 0 10 2001:DB8:400:1::40 1.5 10 20 2001:DB8:400:1::40 3

[0072] (2) Adaptive reconfiguration of timing parameters for QUIC time class

[0073] To achieve adaptive reconfiguration of the QUIC time class timing parameters of the Deep Space Terminal, the specific process is as follows:

[0074] 1) When the deep space terminal establishes a QUIC connection with the ground server and prepares for reliable data transmission, the transmission protocol looks up the latency period table based on the destination node address and the current time, and reads the transmission path latency of the current entry. At that time, the deep space terminal matched The table entry for the interval, with a transmission path latency of 1.5 seconds, is denoted as... ;

[0075] 2) The transmission protocol no longer passively measures and converges end-to-end delay using ACK samples, but instead uses the transmission path delay as a benchmark to directly configure the round-trip delay, so that... ; and configure the duration of the packet loss timer and the detection timer accordingly. , , ,but , ;

[0076] 3) During connection operation, QUIC uses its existing mechanisms to control sending, acknowledgment, and retransmission;

[0077] 4) When the confirmation progress stalls and the probe timer duration is reached, the sending end triggers a probe message. To suppress excessive probing under conditions of long delay and intermittent connectivity, if no progress in the confirmation status is observed after several consecutive PTO triggers, the probe timer duration will be increased according to a multiple backoff rule, for example, by a factor of 2 each time, and a maximum backoff limit will be set to avoid unbounded growth. Once progress in the confirmation status is observed, or any of the following occurs: an entry update or switch in the delay periodic table, the PTO backoff state is reset and returns to the baseline value reconfigured based on the current transmission path delay.

[0078] 5) When When a valid time range is crossed, causing an update or switch in the corresponding entry of the destination node, the transmission protocol re-acquires the delay periodicity table, reads the new entry, and reconfigures the time-related timing parameters accordingly. At that time, the deep space terminal matched The table entry for the interval has a transmission path latency of 3 seconds, meaning... and reconfigure synchronously. , , .

Claims

1. A method for adaptive adjustment of a satellite network transmission protocol timer, characterized in that, Includes the following steps: S1. Based on the pre-generated periodic topology connection relationship of the satellite network, establish a time-varying diagram of the connection relationship, perform link planning, obtain the transmission path delay from the current node to different destination nodes in different time intervals, and form a delay periodic table based on time-period connections; when there are multiple candidate entries that simultaneously meet the valid time range, the entry with the smallest transmission path delay is selected as the current active entry. S2. Store and maintain the time-based connection delay period table in each node, enabling the transmission protocol to be based on the destination node address. and the current system time Real-time lookup of transmission path latency for the current time window ; S3. During connection establishment and operation, the transport layer uses the read transmission path delay value as a reference to adjust the timing parameters of the satellite network transmission protocol: Round trip delay Directly adopt Configure the initial round-trip time using the following formula: ； Packet loss timer Combined with system resolution and magnification factor The calculation is performed using the following formula: ； Detection timer Introducing a safety factor To suppress overprobeing, the formula is: ； S4. When the current system time... When the effective time range is exceeded, causing a change in the delay periodicity table entry, or when the acknowledgment message is detected to be advancing its acknowledgment progress, the transmission protocol automatically triggers the reconfiguration of timer parameters and the reset of the probe timer backoff state, so that it is re-based on the transmission path delay at the current moment. Run at the baseline value.

2. The satellite network transmission protocol timer adaptive adjustment method according to claim 1, characterized in that: The time delay period table based on time-based connections described in step S1 includes: start time, end time, destination node address, and transmission path delay fields.

3. The satellite network transmission protocol timer adaptive adjustment method according to claim 1, characterized in that: The time delay periodic table based on time-period connections described in step S1 is generated in the following way: Including the following two types: 1) The results are calculated uniformly by either the ground mission planning and network management system and uploaded to each node; 2) Calculated by the on-board node and generated locally on the node.

Images