CN103152290B - A kind of broadband multimedia satellite system Bandwidth Dynamic dispatching method - Google Patents

Abstract

The invention discloses a kind of broadband multimedia satellite system Bandwidth Dynamic dispatching method, the method comprises bandwidth request list update, determine the real number allocation result of bandwidth request, transfer the real number allocation result of bandwidth request to integer, distribute the remaining time slots operating procedure that four periodic sequence start, the method can taken into account in broadband multimedia satellite system while packet transfer delay performance, improves the fairness of bandwidth scheduling service.

Description

A Dynamic Bandwidth Scheduling Method for Broadband Multimedia Satellite System

technical field

The present invention relates to a bandwidth scheduling method in a broadband multimedia satellite system, in particular to a bandwidth dynamic scheduling method in a broadband multimedia satellite system using a multi-frequency time division multiple access (Multi-frequency Time Division Multiple Access MF-TDMA) system .

Background technique

The broadband multimedia satellite system is characterized by the transmission of high-speed broadband multimedia services and has developed rapidly in recent years. Compared with the traditional satellite communication system, its biggest difference is that the business carried by it has changed from low-speed data and voice services to high-speed, interactive multimedia services integrating images, audio, video and text. Since the system carries more users and more sudden business, it brings more serious challenges to the bandwidth management of the system.

In order to efficiently utilize bandwidth resources, most of the existing broadband multimedia satellite systems adopt the MF-TDMA system, and its bandwidth management is divided into two levels: connection and burst: the connection layer is mainly for connection admission control for real-time services such as voice and video; The sending layer is mainly for dynamic scheduling of bandwidth for non-real-time services such as web pages and e-mails. Compared with fixed allocation and random allocation, dynamic bandwidth scheduling can ensure the reliable transmission of services and realize the statistical multiplexing of bandwidth for different terminals and different service connections in the satellite beam coverage area, which greatly improves the utilization rate of system bandwidth. It is a broadband multimedia satellite The main strategy adopted by the system bandwidth management.

The representative bandwidth dynamic scheduling algorithm in the broadband multimedia satellite system is proposed by Le-Ngoc et al. [1] in the document "Interactive Multimedia Satellite Access Communications, IEEE Communications Magazine, vol.41, pp.78-85, 2003" The Combined Free/Demand Assignment Multiple Access (Combined Free/Demand Assignment Multiple Access CFDAMA) protocol family and its variants. The widely used digital video broadcast system (Digital Video Broadcast-Return Channel via Satellite DVB-RCS) standard based on the satellite return link is based on this agreement. The CFDAMA protocol adopts a policy of first-come-first-serve based on bandwidth requests, and the first-come-first-serve method is based on bandwidth requests. The problem with this method is that first-come-first-serve cannot guarantee the service well priority.

In order to solve this problem, Lee Ki-dong et al. wrote "A real-time algorithm for timeslot assignment in multirate return channels of interactive satellite multimedia networks, IEEE Journal on Selected Areas in Communications, vol.22, pp.518-528, 2004. "Proposed a method for bandwidth scheduling based on terminal priority weights. This method divides terminals into different priorities according to the types of services carried by the terminals. Bandwidth scheduling is based on pre-divided priorities. The problem with this method is that the priority of the terminal But it is difficult to change if it is determined. This method is called Fixed Priority Based Scheduling (FPS) algorithm here, and this method cannot ensure the fairness of bandwidth scheduling between terminals of the same priority;

In order to solve this problem, Nicola et al. proposed in the document "An IP-based satellite communication system architecture for interactive multimedia services," International Journal of Satellite Communications and Networking, vol. The bandwidth request of the level terminal is served in a skipping manner, which is called the Skipping Priority based Scheduling (SPS) algorithm here, but this algorithm does not take into account the packet transmission timing (Packet Transmission) of the terminal in the MF-TDMA system. The influence of Opportunity PTO) on the order in which bandwidth requests are sent;

In order to solve this problem, W.K.Chai et al. proposed a scheduling algorithm in the order of packet waiting time in the document "Scheduling for proportionally differentiated service provision in geostationary bandwidth on demand satellite networks, GLOBALCOM2005, pp.3722-3727", which is called waiting time priority here Scheduling (Waiting TimePriority Scheduling WTPS) algorithm, which improves the system packet transmission delay performance, but it is difficult to guarantee the fairness of the service under high load, especially when the system is "overloaded". To sum up, the existing bandwidth dynamic scheduling algorithms do not take into account the overall consideration of bandwidth scheduling service fairness and packet transmission delay performance.

Contents of the invention

The purpose of the present invention is to propose a bandwidth dynamic scheduling method suitable for MF-TDMA wideband multimedia satellite system. The method can improve the fairness of bandwidth scheduling service while taking into account the delay performance of packet transmission in the broadband multimedia satellite system.

The technical scheme of the present invention is: a kind of broadband multimedia satellite system bandwidth dynamic dispatching method, it is characterized in that, this method comprises the operation steps of four periodical sequential starts:

Step 1: update the bandwidth request list, that is, update the status of the bandwidth request in the list, and read the newly arrived bandwidth request in the previous bandwidth scheduling cycle into the bandwidth request list;

Step 2: Determine the real number distribution result of the bandwidth request, that is, take the waiting time of the bandwidth request as priority and adopt a fairness scheduling algorithm to determine the real number distribution result of each bandwidth request according to the number of time slot requests of each bandwidth request;

Step 3: Convert the real number allocation result of the bandwidth request into an integer, that is, round down the real number allocation result obtained in step 2 to obtain the corresponding integer allocation result;

Step 4: Allocate the remaining time slots, that is, according to the integer allocation result obtained in step 3, allocate the remaining available time slots in the system one by one in order of bandwidth request priority from high to low and terminal serial numbers from large to small.

Further, in step 1, a bandwidth request list needs to be maintained, which is characterized in that the list arranges the bandwidth requests according to the terminal serial numbers from 1 to Q, where Q is a positive integer greater than 1, and maintains L priority slots for each terminal The lowest priority is 1, and the highest is L, where L is a positive integer greater than 1. Each bandwidth request is identified by the number of timeslot requests x _{i, j} and the waiting time T _{i, j} of bandwidth requests , where i is the serial number of the terminal, and j is the priority identification.

Further, the method for updating the bandwidth request list in step 1 specifically includes:

Step 1.1: update the status of the bandwidth request of each terminal priority L according to formulas (1) and (2);

x _{i, L} = x _{i, L-1} + x _{i, L} i∈[1...Q] (1)

T _{i, L} = T _{i, L} + T i∈[1...Q] (2)

Step 1.2: Update the status of the bandwidth requests of priority levels L-1 to 2 in sequence according to formulas (3) and (4);

x _{i, j} = x _{i, j-1} i∈[1...Q] j∈[2...L-1] (3)

T _{i, j} = T _{i, j-1} +T i∈[1...Q] j∈[2...L-1] (4)

Step 1.3: Update the status of the bandwidth request with priority 1 in the list according to the bandwidth request R _i arriving in the previous scheduling period according to formula (5).

x _i,1 =R _i i∈[1...Q] (5)

Further, in step 2, with the bandwidth request waiting time T _{i, j} as the priority, use the fairness scheduling algorithm to determine the real number allocation result y _{x of} each bandwidth request according to the number of time slot requests x _{i, j} of each bandwidth request, _j , where y _{i, j} is a positive real number, the specific steps for determining the real number distribution result y _{i, j} include:

Step 2.1: Initialize variable λ ^(k) = 0.01 k = 1;

Step 2.2: Initialize variables i=1...Qn=1;

Step 2.3: Calculate y _{i, j} according to formula (6), and determine the value of y _{i, j} according to formula (7).

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Step 2.4: Update according to formula (8)

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Wherein R _max is the upper limit of the number of requests per terminal time slot, which is a positive integer greater than 1.

Step 2.5: Determine whether formula (9) is true, if true, go to step 2.6, if not, execute n=n+1, and go to step 2.3;

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 0.1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

Step 2.6: Update λ ^{(k+1) according to formula (10)} ;

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

Where C is the total number of time slots available in the system, which is a positive integer greater than 1.

Step 2.7: Determine whether formula (11) is true, if true, save the real number distribution results y _{i, j} and go to step 3, if not, execute k=k+1, and go to step 2.2;

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 0.1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Further, in step 3, the real number distribution result _{yi and j} obtained in step 2 are rounded down, and the method of obtaining the integer distribution result is carried out according to formula (12);

Further, the specific steps of allocating remaining time slots in step 4 include:

Step 4.1: Obtain the number of remaining time slots C _remain according to formula (13);

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; remain</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

Step 4.2: let i=Q, jL;

Step 4.3: Calculate y _{i, j} according to formula (14);

y _i,j =y _i,j +min( _xi,j -y _i,j ,C _remain ) (14)

Step 4.4: Update C _remain according to formula (15), if C _remain >0, then execute step 4.5, otherwise go to step 4.7;

C _remain ＝C _remain −min(x _{i, j} −y _{i, j} , C _remain ) (15)

Step 4.5: If i>1, execute i=i-1 and go to step 4.3, otherwise go to step 4.6

Step 4.6: If j>1, execute j=j-1, i=Q and go to step 4.3, otherwise go to step 4.7.

Step 4.7: Update the time slot request number of each bandwidth request in the bandwidth request list according to formula (16).

x _i,j =y _i,j -x _i,j (16)

The beneficial effects of adopting the present invention are: since the present invention takes the waiting time of bandwidth request as the priority of bandwidth scheduling, it can improve the real-time performance of packet transmission under high-load business conditions in the system, and it can effectively guarantee Fairness in the bandwidth scheduling process.

Description of drawings

Fig. 1 is a work flow chart of the present invention;

Fig. 2 is in adopting PowONOFF service source, under the situation that the normalized system service load is 0.95, the end-to-end transmission time delay probability cumulative distribution contrast chart of the present invention and other algorithms;

Fig. 3 is a comparison diagram of the cumulative distribution of end-to-end transmission delay probabilities between the present invention and other algorithms when the PowONOFF service source is used and the normalized system service load is 0.97;

Fig. 4 is under the situation that adopts PowONOFF business source, the service fairness contrast chart of the present invention and other algorithms;

Figure 5 is a comparison diagram of the cumulative distribution of end-to-end transmission delay probabilities between the present invention and other algorithms when the ExpONOFF service source is used and the normalized system service load is 0.95;

Figure 6 is a comparison diagram of the cumulative distribution of end-to-end transmission delay probabilities between the present invention and other algorithms when the ExpONOFF service source is used and the normalized system service load is 0.97;

Fig. 7 is under the situation that adopts ExpONOFF business source, the service fairness contrast chart of the present invention and other algorithms;

Detailed ways

The specific technical solution of the present invention will be described below in conjunction with accompanying drawings 1-7.

As shown in FIG. 1 , the present invention is realized through four sequentially activated operation steps, and the activated period is T (unit is millisecond). T may be an MF-TDMA frame length or an integer multiple of the frame length. The MF-TDMA frame length can be designed according to system requirements, for example, it can refer to the design in the Digital Video Broadcasting-Return Channel via Satellite DVB-RCS (Digital videobroadcasting-return channel via satellite DVB-RCS) standard formulated by the European Telecommunications Standardization Organization. The MF-TDMA frame length is 26.5 milliseconds.

Step 1: update the bandwidth request list, that is, update the status of the bandwidth request in the bandwidth request list, and read the newly arrived bandwidth request in the previous bandwidth scheduling cycle into the bandwidth request list. Table 1 gives an example of a bandwidth request list. It can be seen from the table that the terminal serial numbers are arranged in the order of 1 to Q, where Q is a positive integer greater than 1, and each terminal has L priority bandwidth requests. The lowest priority is 1, the highest is L, where L is a positive integer greater than 1, and each bandwidth request is identified by the number of timeslot requests x _{i, j} and the waiting time T _{i, j} of bandwidth requests, where x _{i, j} is a positive integer, T _{i, j} is a positive real number, i is the serial number of the terminal, and j is the priority identification.

Table 1 Example of bandwidth request list

Terminal serial number priority 1 ... priority j ... Priority L 1 x _1,1 /T _1,1 ... x _1,j /T _1,j ... x _1,L /T _1,L 2 x _2,1 /T _2,1 ... x _2,j /T _2,j ... x _2,L /T _2,L : : : : : : i x _i,1 /T _i,1 ... x _i,j /T _i,j x _i,L /T _i,L : : ... Q X _Q,1 /T _Q,1 ... x _Q,j /T _Q,j x _Q,L /T _Q,L

Further, step 1 can be divided into the following three operation steps:

Step 1.1: update the status of the bandwidth request of each terminal priority L according to formulas (1) and (2);

x _{i, L} = x _{i, L-1} + x _{i, L} i∈[1...Q] (1)

T _{i, L} = T _{i, L} + T i∈[1...Q] (2)

Step 1.2: Update the status of the bandwidth requests of priority levels L-1 to 2 in sequence according to formulas (3) and (4);

x _{i, j} = x _{i, j-1} i∈[1...Q] j∈[2...L-1] (3)

T _i,j =T _i,j-1 +T i∈[1...Q] j∈[2...L-1] (4)

Step 1.3: Update the status of the bandwidth request with priority 1 in the list according to the bandwidth request R _i arriving in the previous scheduling period according to formula (5).

x _i,1 =R _i i∈[1...Q] (5)

Step 2: Determine the real number allocation result of the bandwidth request. Taking the bandwidth request waiting time T _{i, j} as the priority, adopt the fairness scheduling algorithm to determine the real number distribution result y _{i, j} of each bandwidth request according to the number of time slot requests x _{i, j} of each bandwidth request, where y _{i, j} is positive real number;

Further, step 2 can be divided into 7 operation steps. In this embodiment, the total number of time slots available in the system is C, and the upper limit of the number of time slot requests per terminal is R _max .

Step 2.1: Initialize variable λ ^(k) = 0.01 k = 1;

Step 2.2: Initialize variables i=1...Qn=1;

Step 2.3: Calculate y _{i, j} according to formula (6), and determine the value of y _{i, j} according to formula (7).

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Step 2.4: Update according to formula (8)

${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Step 2.5: Determine whether formula (9) is true, if true, go to step 2.6, if not, execute n=n+1, and go to step 2.3;

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 0.1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

Step 2.6: Update λ ^{(k+1) according to formula (10)} ;

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

Step 2.7: Determine whether formula (11) is true, if true, save the real number distribution results y _{i, j} and go to step 3, if not, execute k=k+1, and go to step 2.2;

$<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Step 3: Round down the real number distribution results y _{i and j} obtained in step 2 according to formula (12) to obtain the integer distribution results;

Step 4: Allocate remaining time slots. That is, according to the integer allocation result obtained in step 3, the remaining available time slots in the system are allocated one by one in the order of bandwidth request priorities from L to 1, and terminal serial numbers from Q to 1. Further, it can be divided into the following seven steps:

Step 4.1: Obtain the number of remaining time slots C _remain according to formula (13);

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; remain</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

Step 4.2: let i=Q, jL;

Step 4.3: Calculate y _{i, j} according to formula (14);

y _i,j =y _i,j +min( _xi,j -y _i,j ,C _remain ) (14)

Step 4.4: Update C _remain according to formula (15), if C _remain >0, then execute step 4.5, otherwise go to step 4.7;

C _remain ＝C _remain −min(x _{i, j} −y _{i, j} , C _remain ) (15)

Step 4.5: If i>1, execute i=i-1 and go to step 4.3, otherwise go to step 4.6

Step 4.6: If j>1, execute j=j-1, i=Q and go to step 4.3, otherwise go to step 4.7.

Step 4.7: Update the time slot request number of each bandwidth request in the bandwidth request list according to formula (16).

x _i,j =y _i,j -x _i,j (16)

Under the environment of OPNET Modeler14.0, the implementation benefit of the present invention is verified by computer simulation experiments, and the simulation adopts two kinds of business models, PowONOFF and ExpONOFF, and relevant parameters are as shown in Table 2. Metrics include packet end-to-end transmission delay and service fairness. The packet transmission delay is measured by the probability cumulative distribution function (Cumulative Distribution Function CDF), and the service fairness is measured by the fairness factor Y, which is obtained by formula (17).

$\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; QL</span>}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 17</span>}<span\; class="notranslate">\; )</span>$

Table 2 Simulation parameters

parameter value frame length (seconds) 0.192 slot/frame 1024 cell/slot 1 Uplink Basic Information Rate 2.048Mbps Downlink multiplexing mode Statistical multiplexing downlink basic information rate 8.192Mbps On-board exchange system ATMs business source model PowONOFF/ExpONOFF Normalized system business load 0.1-0.97 Simulation time (seconds) 180

Figure 2 and Figure 3 show the comparison of packet end-to-end transmission delay performance when the service source model is PowONOFF and the load is 0.95 and 0.97. The horizontal axis is the end-to-end packet transmission delay value, and the vertical axis is the corresponding Probability cumulative distribution function. It can be seen from the figure that the delay performance of the SPS algorithm is the worst when the load is 0.95, and the delay performance of the FPS algorithm is the worst when the load is 0.97. This shows that the SPS algorithm cannot always improve the delay performance of the system. Under these two load conditions, the packet transmission delay performance of the present invention is better than the other two algorithms, which is mainly because the present invention fully considers the waiting time of data packets at the terminal buffer in the process of bandwidth scheduling.

Figure 4 shows the comparison of service fairness when the input is the PowONOFF model, the horizontal axis is the normalized system business load, and the vertical axis is the fairness factor. The larger the fairness factor, the better the service fairness. It can be seen from the figure that under low service load conditions, various algorithms can fully meet the bandwidth requirements of the terminal, so the fairness factor is 1. After the load is greater than 0.9, due to the burstiness of the business, the system business is overloaded in some time periods, the terminal bandwidth request cannot be satisfied, and the service fairness is affected. In contrast, the present invention adopts a fair scheduling strategy, so the fairness factor consistently outperforms the other two algorithms.

Figure 5 and Figure 6 show the comparison of packet transmission delay performance when the input is the ExpONOFF service source load is 0.95 and 0.97 respectively, the horizontal axis is the end-to-end packet transmission delay value, and the vertical axis is the corresponding probability cumulative distribution function . As can be seen from the figure, the packet transmission delay performance of the present invention is better than the other two algorithms,

Figure 7 shows the comparison of service fairness when the input is the ExpONOFF model, the horizontal axis is the normalized system business load, and the vertical axis is the fairness factor. The larger the fairness factor, the better the service fairness. It can be seen from the figure that under low service load conditions, various algorithms can fully meet the bandwidth requirements of the terminal, so the fairness factor is 1. After the load is greater than 0.9, due to the suddenness of the business, the system business is overloaded in some time periods, the terminal bandwidth cannot be satisfied, and the service fairness is affected. In contrast, the present invention adopts a fair scheduling strategy, so the fairness factor consistently outperforms the other two algorithms.

Claims (4)

1. a broadband multimedia satellite system bandwidth dynamic scheduling method, is characterized in that, the method comprises the operation step that four periodical sequences start: Step 1: update the bandwidth request list, that is, update the status of the bandwidth request in the list, and read the newly arrived bandwidth request in the previous bandwidth scheduling cycle into the bandwidth request list; Step 2: Determine the real number distribution result of the bandwidth request, that is, take the waiting time of the bandwidth request as priority and adopt a fairness scheduling algorithm to determine the real number distribution result of each bandwidth request according to the number of time slot requests of each bandwidth request; Step 3: Convert the real number allocation result of the bandwidth request into an integer, that is, round down the real number allocation result obtained in step 2 to obtain the corresponding integer allocation result; Step 4: Allocate the remaining time slots, that is, according to the integer allocation result obtained in step 3, allocate the remaining available time slots in the system one by one in order of bandwidth request priority from high to low, and terminal serial numbers from large to small; In step 2, the bandwidth request waiting time T _i,j is the priority, and the fairness scheduling algorithm is used to determine the real number allocation result y _i,j of each bandwidth request according to the number of time slot requests x _i,j of each bandwidth request, Where y _{i, j} are positive real numbers, the specific steps for determining the real number distribution result y _{i, j} include: Step 2.1: Initialize variable λ ^(k) = 0.01 k = 1; Step 2.2: Initialize variable N _i ⁽ⁿ⁾ =0.01 i=1...Q n=1; Step 2.3: Calculate y _{i, j} according to formula (6), and determine the value of y _{i, j} according to formula (7); ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$ ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\\ {\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; ></span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$ Step 2.4: Update according to formula (8) ${\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>}_{}$ Where R _max is the upper limit of the number of requests per terminal time slot, which is a positive integer greater than 1; Step 2.5: judge whether formula (9) is established, if established, then go to step 2.6, if not, execute n=n+1, and go to step 2.3; $<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 0.1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$ Step 2.6: update λ ^{(k+1) according to formula (10)} ; ${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 0.01</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$ Where C is the total number of time slots available in the system, which is a positive integer greater than 1; $<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span><span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; 0.1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$ Step 2.7: Determine whether formula (11) is true, if true, save the real number distribution result y _{i, j} and go to step 3, if not, execute k=k+1, and go to step 2.2; The list arranges the bandwidth requests according to the terminal serial numbers from 1 to Q, where Q is a positive integer greater than 1, and maintains L priority bandwidth requests for each terminal, the lowest priority is 1, and the highest is L, where L is a positive integer greater than 1, and each bandwidth request is identified by the number of time slot requests x _i,j and the waiting time T _i,j of the bandwidth request, where i is the terminal serial number, and j is the priority identification. 2. The method according to claim 1, wherein the method for updating the bandwidth request list in step 1 specifically comprises: Step 1.1: update the status of the bandwidth request of each terminal priority L according to formulas (1) and (2); x _{i, L} = x _{i, L-1} + x _{i, L} i∈[1...Q] (1) T _i,L ＝T _i,L +T i∈[1...Q] (2) Step 1.2: Update the status of the bandwidth requests of priority levels L-1 to 2 in sequence according to formulas (3) and (4); x _{i, j} = x _{i, j-1} i∈[1...Q] j∈[2...L-1] (3) T _i,j ＝T _i,j-1 +T i∈[1…Q] j∈[2…L-1] (4) x _i,1 =R _i i∈[1...Q] (5) Step 1.3: Update the status of the bandwidth request with priority 1 in the list according to the bandwidth request R _i arriving in the previous scheduling period according to formula (5). ${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}}$ 3. method as claimed in claim 1, is characterized in that, in step 3, the real number distribution result _{yi, j} obtained in said step 2 is rounded down, The method to obtain the integer distribution result is according to formula (12). 4. The method according to claim 1, characterized in that, the concrete steps of allocating remaining time slots in step 4 comprise: Step 4.1: Obtain the number of remaining time slots C _remain according to formula (13); ${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; remain</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$ Step 4.2: let i=Q, j=L; Step 4.3: Calculate y _i,j according to formula (14); y _i,j =y _i,j +min( _xi,j -y _i,j ,C _remain ) (14) Step 4.4: Update C _remain according to formula (15), if C _remain >0, then execute step 4.5, otherwise go to step 4.7; C _remain ＝C _remain -min( _xi,j -y _i,j ,C _remain ) (15) Step 4.5: If i>1, execute i=i-1 and go to step 4.3, otherwise go to step 4.6 Step 4.6: If j>1, execute j=j-1, i=Q and go to step 4.3, otherwise go to step 4.7; x _i,j =y _i,j -x _i,j (16) Step 4.7: Update the time slot request number of each bandwidth request in the bandwidth request list according to formula (16).