CN-122026982-A - Method and system for scheduling code transmission service of satellite terminal

CN122026982ACN 122026982 ACN122026982 ACN 122026982ACN-122026982-A

Abstract

The invention discloses a method and a system for scheduling coding transmission service of a satellite terminal, which comprise the steps of taking a repair packet as an independent virtual stream into a unified scheduling frame, deriving a virtual repair stream weight, introducing a WFQ scheduling algorithm, calculating virtual completion time of the packet to be scheduled through the weight and system virtual time, ensuring that bandwidth allocation of the repair stream is proportional to the weight, introducing a DRR scheduling algorithm, maintaining a red word counter for each stream in a round robin scheduling mode, realizing approximate proportional fairness with complexity of decision time, and being suitable for satellite terminal environments with limited resources. The invention effectively solves the problem of transmission reliability in a long-time delay and high packet loss environment in a non-ground network by taking the repair packet as an independent virtual stream into a unified scheduling framework. The repair flow and each service flow participate in scheduling decision together, the weight of the repair flow is calculated dynamically based on the network packet loss rate, and the optimal balance of transmission reliability and bandwidth efficiency is realized.

Inventors

LI YE
WANG YING
WANG TINGTING
HU YINGDONG
WANG JUE

Assignees

南通大学

Dates

Publication Date: 20260512
Application Date: 20251223

Claims (9)

1. The method for scheduling the coded transmission service of the satellite terminal is characterized by comprising the following steps: step 1, a virtual repair flow weight is deduced by taking a repair packet as an independent virtual flow into a unified scheduling framework; Step 2, regarding the repair packet as the first Virtual flows are introduced into a weighted fair queue WFQ scheduling algorithm, virtual completion time of the packets to be scheduled is calculated through weights and system virtual time, and bandwidth allocation of the repair flows is guaranteed to be proportional to the weights; and step 3, introducing a red polling (DRR) scheduling algorithm, maintaining a red counter for each stream by adopting a round-robin scheduling mode, realizing approximate proportional fairness with the complexity of decision time, and being suitable for the satellite terminal environment with limited resources.
2. The method for scheduling coded transmission services of a satellite terminal according to claim 1, wherein in step 1, the unified scheduling framework includes: traffic flow presence Each of the traffic flows A buffer area is arranged, and the packet enters the buffer area in a poisson-pareto burst process; Weight assignment-each traffic flow is assigned a weight Representing relative importance; scheduler, selectable per time slot One of the actions.
3. The method for scheduling coded transmission services of a satellite terminal according to claim 1, wherein step 1 comprises the steps of Individual selection of actions Traffic flow The buffer of the queue head packet is fetched and sent as a source packet, and the method comprises the following steps of Generating and transmitting a repair packet based on random linear combination of unacknowledged source packets, wherein the packet loss rate of a link is I.e. with probability per packet Loss, propagation delay of The sender maintains the unacknowledged packet list, the receiver uses the instant Gaussian elimination decoder to detect the interruption of ordered delivery and activate the decoding, when the number of packets is repaired The lost packet can be recovered when the number of the lost packets is increased, wherein the flow in the time period The proportion of packets delivered in order is called the order delivery proportion Match ordered delivery ratio And weight of The ratio relation of (a), namely: ; Deducing the first The weight of each virtual repair flow is firstly set as the proportion of source packets in the total transmitted packets The repair packet ratio is The following steps are: ; Set the source packet transmission rate as The repair packet transmission rate is P e is the link packet loss rate, the number of repair packets received by the receiving end is To recover from loss Individual source packets, need to satisfy: ; Namely: ; Due to And (2) and Substituting to obtain: ; And (3) solving to obtain: ; to ensure margin, repair packet proportion is required Is higher than I.e. Repair packet flow corresponding weights The proportional relationship with other streams can be expressed as: ; Repair flow weights may be obtained: ; Wherein the method comprises the steps of Is an extra repair packet proportion and satisfies the constraint 。
4. The method for scheduling coded transmission traffic of a satellite terminal according to claim 3, wherein step 2 comprises the steps of WFQ scheduling algorithm maintaining a virtual completion time for each stream i Assigning weights to traffic flows The repair flow weight is When a scheduler prepares to schedule a packet for forwarding, the algorithm compares all the packets at the head of the queue and selects the packet with the minimum virtual completion time for forwarding, and the principle of the WFQ algorithm is as follows: System virtual time initialization and calculation, system virtual time initialization is 0 at the beginning, as an event every time a packet arrives or leaves, global virtual time when event occurs Updating is performed according to the following formula: ; In the formula, Represent the first The moment at which the individual events occur, Expressed as a time interval length, and satisfies ; Initializing and calculating virtual start time and virtual completion time, initializing the virtual start time and the virtual completion time to 0, and calculating the virtual start time and the virtual completion time according to the system virtual time when the packet arrives, wherein the calculation formula is as follows: ; ; In the formula, For the packet arrival time, S i k is a virtual start time, representing the time when the packet starts to be served on the virtual time axis, The virtual completion time is the time when the grouping completes the service on the virtual time axis; At each scheduled time slot, the scheduler performs an update of the virtual time Calculating virtual completion time of each stream; Selecting a streaming service with minimum virtual completion time if a traffic stream is selected If a repair flow is selected, generating a transmission repair packet; By selecting the stream providing service with the minimum virtual completion time, the operation times and input scale required by the execution of the algorithm are realized Is proportional to the logarithm of (i.e. complexity) Proportional fairness and time delay guarantee.
5. The method for scheduling coded transmission service of satellite terminal according to claim 1, wherein step 3 is specifically that in the DRR scheduling algorithm, each service flow is scheduled at the beginning of each round Is given a credit replenishment constant The current credit amount maintained by each service flow is called as a red word Representing the maximum length that the stream can send a packet, each time the scheduler polls the non-empty traffic stream queue If the length of the head data packet of the queue Not greater than Then the data packet is sent and will Subtracting out Up to Less than The DRR adopts a round-robin scheduling mode to maintain a red counter for each stream, realizes approximate proportional fairness with decision time complexity, and is suitable for a satellite terminal environment with limited resources.
6. A coded transmission service scheduling system for a satellite terminal for implementing the method of claim 1, comprising: the repair grouping module comprises a service flow module, a weight distribution module and a scheduler module; the WFQ scheduling algorithm module calculates virtual completion time of the packets to be scheduled through the weight and the system virtual time, and ensures that bandwidth allocation of the repair flow is proportional to the weight; And the DRR scheduling algorithm module maintains a red word counter for each flow in a round-robin scheduling mode, realizes approximate proportional fairness with the complexity of decision time, and is suitable for a satellite terminal environment with limited resources.
7. A computer device comprising a memory, a processor and a computer program stored on the memory, characterized in that the processor executes the computer program to carry out the steps of the method of claim 1.
8. A computer readable storage medium having stored thereon a computer program/instruction which when executed by a processor performs the steps of the method of claim 1.
9. A computer program product comprising computer programs/instructions which, when executed by a processor, implement the steps of the method of claim 1.

Description

Method and system for scheduling code transmission service of satellite terminal Technical Field The invention belongs to the field of data transmission optimization of satellite terminals in satellite communication, and particularly relates to a method and a system for scheduling coding transmission service of a satellite terminal. Background The low-delay packet transmission technology is a key requirement in the field of current satellite communication terminals, and plays a vital role in typical satellite application scenes such as emergency communication, ocean vessels, real-time monitoring and the like. Such services place extremely high demands on the data transmission capabilities of satellite terminals, not only requiring maintenance of stable throughput, but more importantly, must meet stringent low latency and high reliability metrics. In satellite channel environment, any loss or transmission timeout of data packets may directly cause interruption of critical services, which seriously affects the service quality and user experience of the satellite communication system. However, the transmission model of the conventional TCP/IP network and the retransmission-dependent error control mechanism thereof face serious challenges in the environment with long transmission delay and high bit error rate specific to the satellite network. The satellite terminal needs to face the problems of signal attenuation, atmospheric influence, intermittent connection of satellite-to-ground links and the like in the communication process, and the factors make the conventional transmission mechanism based on retransmission difficult to meet the deterministic quality of service requirement of real-time service. In order to improve the transmission reliability of the satellite terminal and reduce the end-to-end delivery delay, the forward erasure coding technology becomes an important solution in the satellite communication system. The technology encodes the original data block at the transmitting side of the satellite terminal to generate redundant data packets, and the receiving terminal can recover the original information by decoding only by successfully receiving enough data packets, thereby effectively adapting to the long time delay characteristic of the satellite link. In a multi-service flow transmission scene of a satellite terminal, a system faces unique scheduling challenges that service flows with different priorities need to share limited satellite link resources, and each service flow has different demands on time delay and reliability, and meanwhile, the satellite terminal also needs to make accurate scheduling decisions between sending an original data packet and a redundant repair packet, so that the repair capability under severe channel conditions is ensured, and the precious bandwidth resources of the satellite link are fully considered. The conventional traffic flow scheduling strategies in satellite terminals, whether scheduling algorithms based on polling or scheduling algorithms based on generalized processor sharing models, mostly adopt predefined static scheduling strategies. These methods perform well in terrestrial network environments where channel conditions are relatively stable, but the limitations of conventional scheduling algorithms are increasingly prominent in dynamically changing satellite network environments, particularly in satellite terminals employing forward erasure coding techniques. The FEC transmission mechanism in the satellite terminal not only changes the characteristics of service flows due to the coding process, but also enables the equivalent service rate to change continuously due to the dynamic fluctuation of satellite link quality, the static scheduling decision based on fixed weight is difficult to adapt to the complex and changeable satellite communication environment, and the self-adaptive optimal resource allocation among multiple service flows cannot be realized, so that the method becomes a key bottleneck for restricting the improvement of the transmission performance of the satellite terminal. Disclosure of Invention The invention aims to provide a method and a system for scheduling coding transmission service of a satellite terminal. The method is focused on designing a controller for multi-service flow scheduling under forward erasure coding transmission so as to realize fair and efficient data delivery in a long-delay and high-packet-loss satellite communication network. By taking the repair packet as an independent virtual stream into a unified scheduling framework, the problem of transmission reliability in a long-time delay and high packet loss environment in a non-ground network is effectively solved. Under the framework, the repair flow and each service flow participate in scheduling decision together, the weight of the repair flow is dynamically calculated based on the network packet loss rate, and the optimal balance of transmission reliability and