CN110808920B

CN110808920B - Satellite communication flow control method with coexistence of CCSDS frame and IP message

Info

Publication number: CN110808920B
Application number: CN201911035659.XA
Authority: CN
Inventors: 陈宇; 卞春江; 陈实; 周海; 李辉; 刘一腾
Original assignee: National Space Science Center of CAS
Current assignee: National Space Science Center of CAS
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2023-05-16
Anticipated expiration: 2039-10-29
Also published as: CN110808920A

Abstract

The invention discloses a satellite communication flow control method for coexistence of CCSDS frames and IP messages, which comprises the following steps: respectively carrying out type identification and marking on the received IP message and CCSDS message; the same type of message is loaded into CCSDS data frames; dynamically allocating bandwidth for various CCSDS data frames by using token overall allocation; putting the CCSDS frame into a corresponding virtual channel; the virtual channels are scheduled based on dynamic scheduling of the urgency of the frame. The method of the invention identifies and marks the IP message and CCSDS message type according to the message multiple specific domain information, and carries out overall bandwidth allocation on the CCSDS data frame based on the frame type, and preferentially schedules the channel with high time delay requirement and high channel weight, thereby improving the service quality of the satellite communication in which the CCSDS protocol and the IP protocol coexist; the method of the invention transmits according to the priority, namely, transmits according to the requirement of QoS index, so that various types of services can meet the QoS index and provide the service quality guarantee.

Description

Satellite communication flow control method with coexistence of CCSDS frame and IP message

Technical Field

The invention relates to the field of satellite communication, in particular to a satellite communication flow control method with coexistence of CCSDS frames and IP messages.

Background

The existing satellite communication flow control method mainly comprises the following three methods:

1. the first come first serve flow control method comprises the following steps: the satellite virtual channels are selected strictly according to the time sequence of frame arrival, i.e. the virtual channel reached by the first frame is selected at the current scheduling moment to occupy the physical channel, and the data frame is sent.

2. The flow control method based on polling scheduling comprises the following steps: the polling scheduling algorithm sequentially selects each virtual channel in turn according to the sequence to occupy the physical channel and send the data frame, namely, a fixed time slice is allocated to each virtual channel in the system, and the virtual channel occupies the physical channel and sends the data frame in the respective time slice.

3. Flow control method based on static priority: according to the different real-time and importance requirements of each virtual channel, each virtual channel is allocated with a static priority, and then the virtual channels are scheduled and selected for transmission according to the static priority, namely, the virtual channel with the highest priority is scheduled and selected to occupy the physical channel and the data frame is transmitted.

In ground and space station communications, the link layer protocol uses a CCSDS data link layer protocol, and the network layer protocol uses both an IP protocol and a CCSDS packet protocol. The information transmission scheme between the satellite and the ground must satisfy the service quality of both the IP message and the CCSDS message. For the task of communication with the space station,

the existing satellite communication flow control method has two disadvantages.

1. The flow control cannot be performed on both IP messages and CCSDS messages.

Specifically, for spatial information transmitted using an IP protocol format and a CCSDS protocol format, i.e., an IP packet and a CCSDS packet, the prior art does not provide a specific transmission scheme capable of satisfying both the IP packet and the CCSDS packet service quality.

2. Existing flow control methods do not provide quality of service (QoS).

The quality of service refers to a series of service requirements that the network is required to meet when transmitting a data stream, and may be specifically quantified as performance indexes such as bandwidth (bandwidth), delay (delay), delay jitter (delay jitter), packet loss rate (packet loss), throughput (throughput), and the like. The QoS aims to provide a specific bandwidth for a specific service, reduce the transmission delay and delay jitter of a message, reduce the packet loss rate, and provide a better and predictable network service. The service in the satellite communication scene and the service in the ground network are concerned with the performance indexes as well, however, the existing satellite communication flow control method cannot distinguish service types and cannot realize service quality guarantee according to specific service types.

Disclosure of Invention

The invention aims to overcome the technical defects and provides a space information transmission flow control method suitable for coexistence of CCSDS protocol and IP protocol so as to ensure the service quality of CCSDS protocol and IP protocol message transmission.

In order to achieve the above object, the present invention provides a method for controlling satellite communication flow in which a CCSDS frame and an IP packet coexist, the method comprising:

respectively carrying out type identification and marking on the received IP message and CCSDS message;

the same type of message is loaded into CCSDS data frames;

dynamically allocating bandwidth for various CCSDS data frames by using token overall allocation;

putting the CCSDS frame into a corresponding virtual channel;

the virtual channels are scheduled based on dynamic scheduling of the urgency of the frame.

As an improvement of the above method, the IP packet is derived from a ground local area network or a space local area network, and the CCSDS packet is derived from a ground local area network or a space local area network; the IP message carries data of satellite service 7, satellite service 6, satellite service 5 and satellite service 4; the CCSDS message carries data of satellite service 3, satellite service 2, satellite service 1 and satellite service 0.

As an improvement of the above method, the type identification and marking of the received IP message and CCSDS message respectively specifically includes:

identifying the service type of data in the IP message; one or more of a source address, a destination address, a source port number, a destination port number, a protocol type and TOS information carried by the IP message;

identifying the service type of the CCSDS frame according to the frame type carried by the CCSDS message;

determining the priority for the IP message according to the service type of the data in the IP message, marking the IP message, and determining the priority for the CCSDS message according to the service type of the data in the CCSDS message;

the priority corresponds to the service types one by one, each service type corresponds to one priority, and each service type corresponds to a plurality of QoS description parameters including time delay, time delay jitter, packet loss rate and throughput.

As an improvement of the above method, the determining the priority is based on: according to the pre-stored corresponding relation between the service type and the priority, the method specifically comprises the following steps:

identifying whether the message carries priority;

if so, searching the corresponding relation between the pre-stored service type and the priority to find the priority corresponding to the service type, judging whether the carried priority is consistent with the found priority, and if not, modifying the priority of the message into the found priority;

if not, searching the corresponding relation between the pre-stored service type and the priority according to the identified service type to find the priority corresponding to the service type, and distributing the priority to the IP message.

As an improvement of the above method, the determining the priority is based on: according to the pre-stored corresponding relation of the service type, the user and the priority, the method specifically comprises the following steps:

identifying whether the message carries priority;

if so, acquiring the information and the service type of the user from the message, searching the corresponding relation of the user, the service type and the priority stored in advance, finding the priority corresponding to the user and the service type, judging whether the carried priority is consistent with the found priority, and if not, modifying the priority of the inconsistent IP message into the found priority;

if not, acquiring the information and the service type of the user from the message, searching the corresponding relation of the pre-stored user, service type and priority according to the information and the identified service type of the user, finding the priority corresponding to the user and the service type, and distributing the priority to the message.

As an improvement of the above method, the method further includes, after performing type identification and marking on the received IP packet and the CCSDS packet, respectively: traffic shaping is used to limit the maximum traffic per class of satellite traffic.

As an improvement of the above method, the loading of the same type of messages into the CCSDS data frame specifically includes:

selecting the IP messages of the same type and packaging the IP messages in a CCSDS frame; when the IP message is packaged, setting a virtual channel identification domain in an AOS frame according to the priority of the IP message, thereby completing the correspondence between the priority of the IP message and the virtual channel;

multiplexing and sectionally loading CCSDS frames with the same priority into packet areas of multiplexing protocol data units with fixed length, and respectively adding MPDU main header, frame main header and frame tail to generate a frame.

As an improvement of the method, the utilization token overall allocation dynamically allocates bandwidth for various CCSDS data frames; the method specifically comprises the following steps:

configuring a token generator and a token bucket for each satellite service; setting an initial bandwidth for each service, each token generator generating tokens at a fixed rate according to the initial bandwidth; the satellite service 7 and the satellite service 6 are allocated in a quota, the satellite service 5, the satellite service 4 and the satellite service 3 are allocated in a full quota and can be borrowed, and the satellite service 2, the satellite service 1 and the satellite service 0 are allocated in a balance and can be expanded;

putting tokens generated by each token generator into a certain token bucket according to a token overall distribution algorithm;

when transmitting satellite service data, a token needs to be obtained from a token bucket of the satellite service to transmit a CCSDS message, and the number of tokens in the token bucket is reduced by 1; if the token bucket has no tokens, the CCSDS message cannot be transmitted.

As an improvement of the above method, the placing the tokens generated by each token generator into a token bucket according to the token overall allocation algorithm specifically includes:

step S1), judging whether the satellite service token bucket is full, if so, entering step S2), otherwise, putting the token into the service token bucket, and ending;

step S2) judging whether the token is a token of the quota allocation service, if so, discarding the token, and ending; otherwise, go to step S3);

step S3) judging that the weight of all balance-scalable service token receivers is 0, and if so, resetting the weight of all balance-scalable service token receivers; and directs to the first balance allocation extensible service; otherwise, entering step S4);

step S4) traversing all balance expandable service token barrels, finding out token barrels which are not full and have non-zero weight, placing tokens and ending; if not, the token is discarded and ended.

As an improvement of the above method, before placing the CCSDS message into the corresponding virtual channel, the method further includes: when allocating bandwidth for data with service type of satellite service 3, satellite service 2, satellite service 1 or satellite service 0, scheduling the IP data packet specifically includes:

sending various CCSDS messages into corresponding IP queues; the IP queues adopt weighted polling queue scheduling, namely, the scheduling is carried out among each queue in turn, so that the messages in each queue can be forwarded to a certain degree.

As an improvement of the above method, the CCSDS messages are put into corresponding virtual channels; the method comprises the following steps:

and acquiring the priority of the message from the CCSDS message, acquiring a corresponding virtual channel according to the pre-stored corresponding relation between the priority of the message and the virtual channel, and transmitting the acquired virtual channel.

As an improvement of the above method, the dynamic scheduling based on the urgency of the frame schedules the virtual channel, specifically including:

the urgency F of the frame is calculated as:

f= (Tmax-Tw) ×p, where Tmax is the maximum scheduling delay allowed by the virtual channel; tw is the time that the frame has been waiting in the virtual channel: the time difference between the current scheduling time kΔt of the virtual channel and the arrival time Ta of the current first frame in the virtual channel is defined as the time that the frame in the virtual channel has been waiting, i.e.:

Tw=kDeltat-TaP is a static priority, the real-time transmission of each virtual channel before starting transmission is called a static priority, a virtual channel with high real-time requirement can be given a static priority with a value of 1, otherwise, a static priority with a number of 10 is given; the maximum value of the static priority is 10, and the minimum value is 1;

firstly, scheduling a virtual channel with a minimum urgency value F of a transmission frame; if two or more virtual channels have the value F of the emergency degree of the minimum frame at the same time, the static priority of the virtual channels needs to be considered, the virtual channels with the minimum static priority value are scheduled and transmitted preferentially, and if more than one channel with the minimum static priority at the same time occurs, the channels with the small sequence numbers are selected and provided with service preferentially.

The invention has the advantages that:

1. the invention identifies and marks the IP message and CCSDS message type according to the message multiple specific domain information, and carries out overall bandwidth allocation on the CCSDS data frame based on the frame type, and preferentially schedules the channel with high time delay requirement and high channel weight, thereby improving the service quality of satellite communication in which the CCSDS protocol and the IP protocol coexist;

2. the method of the invention transmits the spatial information transmitted by adopting the IP format and the CCSDS format according to the priority, namely, the spatial information is transmitted according to the QoS index requirement, so that various types of services can meet the QoS index and the service quality guarantee is provided;

3. the method of the invention meets the QoS requirements of different services in satellite communication and the dynamic bandwidth allocation requirement of satellite channels.

Drawings

FIG. 1 is a satellite communication protocol architecture;

FIG. 2 is a schematic diagram of a flow control method of the present invention;

FIG. 3 is a schematic diagram of a traffic shaping process according to the present invention;

fig. 4 is a schematic diagram of MPDU encapsulation for a fixed slot-with padding;

fig. 5 is a schematic diagram of MPDU encapsulation for a fixed slot-just filled case;

fig. 6 is a schematic diagram of MPDU encapsulation for a fixed slot-case with remaining packets;

FIG. 7 is a schematic diagram of an IP Over CCSDS encapsulation;

FIG. 8 is a CCSDS frame encapsulation process;

fig. 9 is a flow chart of dynamic bandwidth allocation based on token pool allocation;

FIG. 10 is a flow chart of token pool allocation;

FIG. 11 is a flow chart of IP packet scheduling;

fig. 12 is a flow chart of a virtual channel scheduling algorithm based on the urgency of the frame.

Detailed Description

The technical scheme of the invention is described in detail below with reference to the accompanying drawings and specific embodiments.

Abbreviations and key term definitions are first introduced:

bandwidth: refers to the amount of data that a satellite link can transmit per unit time.

Delay time: refers to the time that network data spends on average from the network entry to the exit. Factors that create delay include packet delay, queuing delay, switching delay, and propagation delay.

Delay jitter: meaning that the time delays presented by different packets in the same traffic stream are different.

Packet loss rate: refers to the ratio of the lost messages to the total number of messages sent.

Throughput: refers to the ability to efficiently transfer data between network users.

The invention provides a satellite communication flow control method with coexistence of CCSDS frames and IP messages, which meets the requirements of different service QoS in satellite communication and the requirements of dynamic bandwidth allocation of satellite channels.

Compared with terrestrial communication, satellite communication transmission has the following three characteristics:

real-time demand differentiation of traffic, for example: the satellite remote control service is the most important data of the proposition, and relates to normal flight and operation of the satellite, and the real-time requirement is highest; the telemetry service is satellite operation information transmitted from a satellite to a ground command center, and has high real-time requirement; voice image services, real-time requirements are common. Local area network services have no requirement for real-time.

The priority of the service is divided into a plurality of grades, the space information is strictly classified according to the urgency, and the priority transmission of the information with high urgency is ensured under the condition of shortage of satellite communication resources.

The space resources for traffic transmission are limited: satellite platforms have limited processing power and satellite communication links have limited bandwidth. The design targets of the flow control method are as follows:

the real-time requirement of time-sensitive business is met; the priority forwarding requirement of the high-priority service is met; the bandwidth utilization rate is improved, and the management and guarantee capacity of the bandwidth is provided.

The satellite communication protocol architecture is shown in fig. 1. The satellite communication protocol architecture employs a CCSDS protocol and an IP protocol. In the protocol system, the application layer includes the transmission of 8 types of satellite services, and the priorities of the satellite services 0 to 7 are sequentially increased. At the network layer, CCSDS space packets carry class 4 traffic and IP and CCSDS encapsulation packets carry class 4 traffic. At the data link layer, the flow control is realized based on CCSDS AOS protocol, which comprises the following steps: frame encapsulation, bandwidth allocation and virtual channel scheduling based on traffic priority. According to the service application mode 4 in table 1, each service corresponds to one virtual channel, as shown in table 1.

Table 1: service type in satellite communications

First, by classifying data by satellite traffic type, as shown in table 1, the data is classified into 8 classes. Allocating a corresponding virtual channel for each type of satellite service; then, carrying out overall dynamic bandwidth allocation on each virtual channel; and finally, scheduling the packaged message according to the priority of each service by adopting a virtual channel dynamic scheduling algorithm based on the emergency degree, and ensuring the priority transmission of important low-delay data. Thus, the method not only meets the QoS requirements of different services in the space-sky information transmission, but also meets the requirements of dynamic bandwidth allocation of the space-sky information transmission.

As shown in fig. 2, the method of the present invention comprises: traffic classification and marking, traffic shaping, packet channel multiplexing, bandwidth allocation, IP packet scheduling, and virtual channel scheduling.

Step 1) service classification and marking:

an IP message is received from a terrestrial local area network or a spatial local area network, and a CCSDS message is received from a terrestrial CCSDS device or a spatial CCSDS device.

The IP packets received by the flow control device carry data of satellite service 7, satellite service 6, satellite service 5, and satellite service 4. The received CCSDS messages carry data of satellite service 3, satellite service 2, satellite service 1, satellite service 0.

The traffic type of the data in the IP packet and the CCSDS packet is identified.

And identifying the service type of the data in the IP message according to one or more of the source address, the destination address, the source port number, the destination port number, the protocol type, the TOS and other information carried by the IP message.

And identifying the service type of the CCSDS frame according to the frame type carried by the CCSDS message.

The priority is determined for the IP message according to the service type of the data in the IP message, the IP message is marked, and the priority is determined for the CCSDS message according to the service type of the data in the CCSDS message.

The method for determining the priority of the messages (IP messages and CCSDS messages) comprises two methods:

table 2: correspondence between service type and priority

First kind: according to the pre-stored corresponding relation between the service type and the priority, as shown in Table 2

1. Identifying whether the message carries priority, if so, searching the corresponding relation between the pre-stored service type and the priority to find the priority corresponding to the service type, judging whether the carried priority is consistent with the found priority, and if not, modifying the priority of the message into the found priority.

2. And identifying whether the message carries the priority, if not, searching the corresponding relation between the pre-stored service type and the priority according to the identified service type to find the priority corresponding to the service type, and distributing the priority to the IP message.

Second kind: according to the pre-stored corresponding relation of service type, user and priority

1. Identifying whether the message carries priority, if so, acquiring the information and the service type of the user from the message, searching the corresponding relation of the user, the service type and the priority stored in advance to find the priority corresponding to the user and the service type, judging whether the carried priority is consistent with the found priority, and if not, modifying the priority of the inconsistent IP message into the found priority.

2. And identifying whether the message carries the priority, if not, acquiring the information and the service type of the user from the message, searching the pre-stored corresponding relation among the user, the service type and the priority according to the information of the user and the identified service type, finding the priority corresponding to the user and the service type, and distributing the priority to the message.

Regarding the setting of the priority: the priorities are in one-to-one correspondence with the service types, and each service type is uniquely corresponding to one priority. Each traffic type corresponds to several QoS descriptive parameters, such as delay, delay jitter, packet loss rate, throughput.

Step 2) traffic shaping

Traffic shaping uses traffic shaping to limit the maximum traffic per class of satellite traffic.

When the message arrives, firstly classifying the message according to a preset matching rule, and then entering a buffer area and a token bucket for processing. And the token bucket is used for placing tokens into the bucket according to the speed set by a user, if enough tokens in the token bucket can be used for sending messages, the messages are directly sent out continuously, and meanwhile, the token amount in the token bucket is correspondingly reduced along with the message sending. When tokens in the token bucket are so few that the message can not be sent any more, the message is cached in the buffer zone (the message which subsequently arrives at the buffer zone, the message which arrives at the buffer zone is detected to directly enter the buffer zone queue, and if the length of the queue reaches the upper limit, the message is directly discarded). When there is a message in the buffer area, the buffer area takes out the message from the buffer area queue according to a certain period to send, and each sending is compared with the number of tokens in the token bucket until the number of tokens in the token bucket is reduced to the point that the message in the buffer area queue can not be sent any more or the message in the buffer area queue is completely sent. As shown in fig. 3.

Step 3) packet channel multiplexing

Frame generation refers to a mechanism that provides a shared virtual channel (frame) for various types of data packets generated by higher layer protocols.

An isochronous frame generation algorithm is employed. The isochronous frame generation algorithm refers to encapsulating the packets arriving at the upper layer into a frame and releasing every fixed period of time. In the source envelope packaging process, three situations may occur:

first kind: in the fixed framing waiting time Sw, if the number of arriving packets N is less than N, the rest MPDU packet area needs to be filled with idle data packets, as shown in FIG. 4;

second kind: during the fixed framing latency Sw, the number of packets arriving N is exactly equal to N, as shown in fig. 5;

third kind: in the fixed framing waiting time Sw, the number of arriving packets N is greater than N, and at this time, only the first N CCSDS packets are encapsulated into one MPDU and transmitted, and the other remaining packets remain in the next MPDU for transmission, as shown in fig. 6.

Packet channel multiplexing of IP messages

The same type of IP message is selected and encapsulated in a CCSDS frame. When the IP message is packaged, the VCID (virtual channel identification domain) identification domain in the AOS frame is set according to the priority of the IP message, so that the correspondence between the priority of the IP message and the virtual channel is completed. As shown in fig. 7.

Packet channel multiplexing of CCSDS frames: the CCSDS frames with the same priority are multiplexed and segmented into packet areas of Multiplexing Protocol Data Units (MPDUs) with fixed length, and MPDU main header, frame main header and frame tail are respectively added, so that a frame is generated. The MPDU is fixed in length within a specific task and fits within the data region of a Virtual Channel Data Unit (VCDU) of a fixed length, and the data structure changes are shown in fig. 8.

Step 4) Bandwidth Allocation

Since various satellite services in satellite communications have different priorities. The invention provides a dynamic bandwidth allocation method based on token overall allocation, and a schematic diagram is shown in fig. 9. The basic composition structure is as follows: a token generator: tokens are generated at a constant rate. Token overall distribution module: and overall distribution is carried out on the tokens in each token bucket. Token bucket: a container of tokens.

A token bucket shaper is configured for each class of traffic flow to shape its traffic. The output flow of each service flow is controlled by the corresponding token bucket, and the parameter setting of the token bucket determines the speed of the output flow and the bandwidth occupation ratio. The token generator of the token bucket and the token bucket are divided, the token generator generates tokens at a fixed rate, the tokens are collected and comprehensively scheduled, and under the condition that the token bucket is not full, all the generated tokens are put into the corresponding token bucket and are used for guaranteeing burst requirements possibly occurring in the data. After the token bucket for the quota allocation service is full, the newly generated tokens are discarded. The full allocation may borrow a token bucket for allocation traffic or balance allocation scalable traffic to fill up and use the newly generated tokens for data transfer rather than discarding. When data to be transmitted in the balance allocation expandable service token bucket cannot be transmitted due to insufficient tokens, newly generated redundant tokens are called into the token bucket with insufficient tokens. Therefore, the link bandwidth sharing among various service types is realized, and the utilization rate of the network bandwidth is improved.

Firstly, bandwidth is allocated for each type of satellite service, and then bandwidth allocation is carried out on all the services based on a token overall allocation mechanism.

Table 3: bandwidth allocation mode of satellite service

The bandwidth allocation method is divided into 3 types: the quota allocation, the full allocation, can be borrowed and the balance allocation can be extended.

Quota allocation: and allocating fixed bandwidth resources, wherein the bandwidth resources of the service are not occupied by other services, and the bandwidth resources of other services are not used. For example, the satellite service 7 and the satellite service 6 adopt a quota allocation manner.

The full allocation may lend itself: and when the traffic flow of the service of the class is smaller than the initial bandwidth, the surplus bandwidth of the service of the class can be borrowed to the balance allocation expandable service. When the service flow of the category is increased, the borrowed bandwidth must be returned to the service bandwidth of the category. The full allocation may borrow out class traffic without borrowing other traffic bandwidth. For example, the satellite service 5, the satellite service 4, and the satellite service 3 are in a full-allocation lendable manner.

Balance allocation is scalable: the initially allocated bandwidth is the remaining bandwidth resources of the flow control device. When the traffic is less than the initial bandwidth, the spare bandwidth can be borrowed for other balance allocation expandable services. When the service flow is increased, other balance allocation expandable services must return the initial bandwidth of the service, and can borrow bandwidth from other services, so that after the maximum bandwidth of each user is reached, other service bandwidths are not borrowed. For example, satellite service 2, satellite service 1, and satellite service 0 employ balance allocation scalability.

The method specifically comprises the following steps:

step 4-1) token generator and token bucket configuration

Each service is configured with a token generator and a token bucket. Tokens generated by each token generator are placed into a certain token bucket according to an overall allocation algorithm. When transmitting certain service data, a token needs to be acquired from the service token bucket to transmit a CCSDS message, and the number of tokens in the token bucket is reduced by 1. If the traffic token bucket has no tokens, no CCSDS message can be transmitted.

Step 4-2) initial Bandwidth

An initial bandwidth is set for each service, and each token generator generates tokens based on the initial bandwidth. The tokens of each service are preferably placed in the token bucket of the service. Thus, when there is a service flow, all services can obtain the initial bandwidth; when the token bucket is full, i.e. no traffic flows, the spare tokens are allocated to other token buckets, i.e. bandwidth is allocated to other traffic.

Step 4-3) token pool allocation

The overall token allocation mode is divided into 3 types:

1. fixed bandwidth

Tokens are put into the corresponding token bucket only and discarded if the token bucket is full.

2. Bandwidth lending

The full-allocation lendable service may lend the excess bandwidth to the balance-allocation expandable service, and the balance-allocation expandable service may lend the excess bandwidth to other balance-allocation expandable services. Bandwidth lending is based on weighted priority rules. And presetting a weight for each service type, and scheduling the surplus tokens according to the weight of each service when the tokens are comprehensively distributed. Ensuring that each service can obtain rich bandwidth allocation in proportion.

3. Bandwidth return

After the bandwidth is borrowed, when the traffic of the service is increased, the borrowed bandwidth returns to the service.

As shown in fig. 10, the token pool allocation algorithm is described as follows:

The token overall allocation strategy has the following characteristics:

1. the quota allocation mode ensures the high-grade service bandwidth: the important service has high requirement on the packet loss rate and the service occupies less bandwidth resource, so the fixed bandwidth can be allocated for the important service by adopting a quota bandwidth allocation mode, and the packet loss rate of the service is ensured to be the minimum value.

2. The full-amount allocation can be borrowed to ensure that the bandwidth of the medium-level service is effectively utilized: an initial bandwidth is set for each service type, and the initial bandwidth can ensure the normal operation of the corresponding service, so that the initial bandwidth is configured according to the maximum value of the application scene. When a certain service flow is low, the service bandwidth can be borrowed to the balance expandable service. When the traffic volume increases, resulting in an insufficient bandwidth left by itself, and its initial bandwidth is occupied by other traffic, its initial bandwidth must be restored. This mechanism ensures efficient utilization of medium level traffic bandwidth.

3. The balance allocation extensible mode ensures the minimum bandwidth of low-grade service: and through a weighted priority token overall allocation strategy, surplus bandwidth is allocated to the service with insufficient bandwidth according to the weight proportion, so that the condition that the service is starved and dead is avoided, and the phenomenon of TCP global synchronization during service recovery is avoided.

From the three characteristics, the dynamic bandwidth allocation strategy based on the token overall allocation provided by the invention firstly meets the initial bandwidth of normal operation of all services, has the dynamic allocation capability of dynamically occupying unused bandwidth among services, and improves the utilization rate of satellite communication bandwidth. Meanwhile, the dynamic allocation mechanism is based on the allocation of the weighted priority rule, and the smooth transition of the network traffic is ensured.

Step 5) IP packet scheduling

When allocating bandwidth for data of traffic types VC3, VC2, VC1, VC0, since these traffic are multi-user IP traffic, IP packet scheduling is required before entering the virtual channel. The scheduling method is shown in the figure. As shown in fig. 11, the specific steps are as follows:

step 5-1) classifying the messages according to CCSDS message types. The satellite services 3-0 are all IP services, one or more IP messages are encapsulated in a CCSDS frame, and the priority of the IP messages is consistent.

Step 5-2) sending various CCSDS messages into corresponding IP queues. The IP queues adopt weighted polling queue scheduling, namely, the scheduling is carried out among each queue in turn, so that the messages in each queue can be forwarded to a certain degree.

As shown in the figure, the IP message output port has N queues, the transmission bandwidth of the output port is M, the priority increases from 1 to N, firstly, corresponding weight values are set for each queue, and the priority is W in turn ₀ -W _N The weight value represents the proportion of the obtained bandwidth, and the bandwidth obtained by the queue x is M x W _x Sum of weight values. For example, the transmission bandwidth of one port is 1000M, the weight values set for 5 queues at the output port are respectively 4, 3, 1 and 1, and the forwarding bandwidth obtained by the corresponding queues is divided400M,300M,100M, respectively.

The WRR queues also have the advantage that although each queue is scheduled in turn, the time to allocate service is not fixed, and when there is no message in a certain priority queue, then the next priority queue will be scheduled, so that bandwidth resources can be fully utilized. The method is suitable for intermittent transmission of IP service.

Step 5-3) putting the CCSDS message into a corresponding virtual channel.

Step 6) virtual channel scheduling

Because the service types transmitted by different virtual channels are different, and the service types corresponding to the priorities are in one-to-one correspondence with the virtual channels, the service types are equivalent to the virtual channels themselves, and have different service system grades. Therefore, the scheduling of virtual channels is also one of the measures for providing quality of service guarantee for different application data.

When the virtual channel scheduling is carried out, the waiting time of the frame in the virtual channel and the maximum time delay allowed by the frame in each virtual channel are considered, so that the real transmission urgency of the frame can be fully reflected, and a virtual channel dynamic scheduling algorithm based on the urgency of the CCSDS frame is provided.

The dynamic scheduling algorithm based on the urgency of the frame involves 3 factors: maximum scheduling delay allowed by the virtual channel, time the frame in the virtual channel has been waiting, static priority.

Maximum allowable scheduling delay Tmax of the virtual channel: each virtual channel has an allowable maximum scheduling delay, and different sources have different requirements on the maximum scheduling delay. Frames in the virtual channel buffer will be lost when the waiting time of those frames exceeds the maximum scheduling delay that it allows.

The time Tw that the frame has been waiting in the virtual channel: the time difference between the current scheduling time kΔt of the virtual channel and the arrival time Ta of the current first frame in the virtual channel is defined as the time that the frame in the virtual channel has been waiting, i.e.:

Tw＝kΔt–Ta (1)

static priority P: the real-time transmission of each virtual channel before starting transmission is called as static priority, and a virtual channel with high real-time requirement can be endowed with a static priority with smaller value, otherwise, a static priority with larger value can be endowed, so that different requirements of different virtual channels on transmission delay are reflected.

The urgency F of a frame may be defined as follows:

F＝(Tmax-Tw)×P (2)

substituting the formula (1) into the formula (2) to obtain:

F＝(Tmax-Tw)×P

＝(Tmax-kΔt+Ta)×P (3)

in the scheduling process, at any asynchronous scheduling time, a virtual channel having a minimum value F of urgency of a transmission frame is first scheduled. This is because the smaller the value F of the urgency of a frame is, the higher the real-time requirement of the virtual channel is. If two or more virtual channels have the value F of the emergency degree of the minimum frame at the same time, the static priority of the virtual channels needs to be considered, the virtual channels with the minimum static priority value are scheduled and transmitted preferentially, and if more than one channel with the minimum static priority at the same time occurs, the channels with the small sequence numbers are selected and provided with service preferentially. As shown in fig. 12.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.

Claims

1. A method for controlling traffic of satellite communication in which a CCSDS frame and an IP message coexist, the method comprising:

step S1), respectively carrying out type identification and marking on the received IP message and CCSDS message; the IP message is from a ground local area network or a space local area network, and the CCSDS message is from the ground local area network or the space local area network; the IP message carries data of satellite service 7, satellite service 6, satellite service 5 and satellite service 4; the CCSDS message carries data of satellite service 3, satellite service 2, satellite service 1 and satellite service 0;

step S2) loading the same type of messages into CCSDS data frames;

step S3), dynamically allocating bandwidth for various CCSDS data frames by using token overall allocation;

step S4) putting various CCSDS data frames into corresponding virtual channels, wherein the steps comprise: respectively placing a CCSDS data frame filled with the IP message and a CCSDS data frame filled with the CCSDS message into corresponding virtual channels; wherein, before the CCSDS data frame filled with the CCSDS message is put into the corresponding virtual channel, the method further comprises the following steps: when the service type is the data of satellite service 3, satellite service 2, satellite service 1 or satellite service 0 is allocated with bandwidth, the IP data packet is scheduled;

step S5), calculating the urgency of the frame, and scheduling the virtual channel based on the dynamic scheduling of the urgency of the frame;

wherein, the step S3) specifically includes:

step S3-1) configuring a token generator and a token bucket for each satellite service; setting an initial bandwidth for each service, each token generator generating tokens at a fixed rate according to the initial bandwidth; the satellite service 7 and the satellite service 6 are allocated in a quota, the satellite service 5, the satellite service 4 and the satellite service 3 are allocated in a full quota and can be borrowed, and the satellite service 2, the satellite service 1 and the satellite service 0 are allocated in a balance and can be expanded;

step S3-2), putting the tokens generated by each token generator into a certain token bucket according to a token overall allocation algorithm;

step S3-3), when transmitting satellite service data, a token is acquired from a token bucket of the satellite service to transmit a CCSDS message, and the number of the tokens in the token bucket is reduced by 1; if the token bucket has no token, the CCSDS message cannot be transmitted;

the step S3-2) specifically comprises the following steps:

step S3-2-1) judging whether the satellite service token bucket is full, if so, entering step S3-2-2), otherwise, putting the token into the service token bucket, and ending;

step S3-2-2) judges whether the token is a token of the quota allocation service, if yes, the token is discarded, and the process is finished; otherwise, enter step S3-2-3);

step S3-2-3) judges that the weight of all balance expandable service token receivers is 0, if yes, resets the weight of all balance expandable service token receivers; and directs to the first balance allocation extensible service; otherwise, enter step S3-2-4);

step S3-2-4), traversing all balance expandable service token barrels, finding out token barrels which are not full and have non-zero weight, placing tokens, and ending; if the token cannot be found, discarding the token, and ending;

in the step S4), when the bandwidth is allocated to the data with the service type being satellite service 3, satellite service 2, satellite service 1 or satellite service 0, the scheduling of the IP packet specifically includes:

sending various CCSDS messages into corresponding IP queues; the IP queues adopt weighted polling queue scheduling, namely, scheduling is carried out among each queue in turn, so that the messages in each queue can be forwarded to a certain degree;

in the step S5) of the above-mentioned process,

the urgency F of the frame is calculated as:

F＝(Tmax-Tw)×P

tmax is the maximum scheduling time delay allowed by the virtual channel; tw is the time that the frame in the virtual channel has been waiting, and the calculation formula is:

Tw＝kΔt–Ta

k delta t is the current scheduling time of the virtual channel, ta is the arrival time of the current first frame in the virtual channel, and P is the static priority, namely the real-time property of the transmission of each virtual channel before starting transmission;

in the step S5), the virtual channel is scheduled based on dynamic scheduling of the urgency of the frame, which specifically includes:

2. The method of claim 1, wherein the type identification and marking of the received IP message and the CCSDS message respectively comprises:

3. The method of claim 2, wherein the determining the priority is based on: according to the pre-stored corresponding relation between the service type and the priority, the method specifically comprises the following steps:

identifying whether the message carries priority;

4. The method of claim 2, wherein the determining the priority is based on: according to the pre-stored corresponding relation of the service type, the user and the priority, the method specifically comprises the following steps:

identifying whether the message carries priority;

5. The method of claim 1, wherein the type identifying and marking of the received IP message and CCSDS message, respectively, further comprises: traffic shaping is used to limit the maximum traffic per class of satellite traffic.

6. The method of claim 4, wherein the same type of messages are loaded into CCSDS data frames, specifically comprising:

7. The method of claim 1, wherein the CCSDS messages are placed into corresponding virtual channels; the method comprises the following steps:

and acquiring the priority of the message from the CCSDS message, acquiring a corresponding virtual channel according to the pre-stored corresponding relation between the priority of the message and the virtual channel, and transmitting the CCSDS message through the virtual channel according to the acquired priority of the message.