阅读说明：本技术 一种低轨卫星系统资源调度方法 (Low-earth-orbit satellite system resource scheduling method ) 是由 柴蓉 刘冲 陈前斌 于 2020-06-15 设计创作，主要内容包括：本发明涉及一种低轨卫星系统资源调度方法,属于无线通信技术领域。该方法包括以下步骤：S1：建模物联网网关关联变量；S2：建模卫星间数据转发变量；S3：建模地面站关联变量；S4：建模物联网网关、卫星及地面站数据缓存模型；S5：建模物联网网关、地面站关联、卫星间数据转发及资源分配限制条件；S6：基于物联网网关最大传输时延最小化确定用户关联及资源调度策略。本发明通过对低轨卫星通信系统联合设计物联网网关关联及资源调度策略,实现物联网网关最大传输时延最小化。(The invention relates to a resource scheduling method for a low-orbit satellite system, and belongs to the technical field of wireless communication. The method comprises the following steps: s1: modeling an internet of things gateway association variable; s2: modeling data forwarding variables among satellites; s3: modeling a ground station association variable; s4: modeling an internet of things gateway, a satellite and a ground station data cache model; s5: modeling an internet of things gateway, associating ground stations, forwarding data among satellites and limiting conditions of resource allocation; s6: and determining a user association and resource scheduling strategy based on the maximum transmission delay minimization of the gateway of the Internet of things. According to the invention, the maximum transmission delay minimization of the gateway of the Internet of things is realized by jointly designing the gateway association and resource scheduling strategy of the Internet of things for the low-orbit satellite communication system.)

1. A method for scheduling low earth orbit satellite system resources is characterized in that: the method comprises the following steps:

s1: modeling an internet of things gateway association variable;

s2: modeling data forwarding variables among satellites;

s3: modeling a ground station association variable;

s4: modeling an internet of things gateway, a satellite and a ground station data cache model;

s5: modeling an internet of things gateway, ground station association and resource allocation limiting conditions;

s6: and determining a user association and resource scheduling strategy based on the maximum transmission delay minimization of the gateway of the Internet of things.

2. The method of claim 1, wherein the method further comprises: enabling the number of the internet of things gateways to be N, the number of the satellites to be M and the number of the ground stations to be K; g_nRepresents the nth gateway of the Internet of things, S_mDenotes the m-th satellite, V_kRepresenting the kth ground station, N is more than or equal to 1 and less than or equal to N, M is more than or equal to 1 and less than or equal to M, and K is more than or equal to 1 and less than or equal to K.

3. The method of claim 2, wherein the method further comprises: in step S1, the modeling internet of things gateway association selection variables specifically include: let u_n,m,t∈ {0,1} is gateway G of Internet of things_nAnd satellite S_mAssociated variable in the t-th time slot, if u_n,m,t1, denotes the internet of things gateway G_nAnd satellite S_mAssociating in the t-th time slot, otherwise u_n,m,t＝0。

4. The method for scheduling resource of low earth orbit satellite system of claim 3, wherein the step S2 of modeling the inter-satellite data transmission variables comprises signaling α_m,l,t∈ {0,1} denotes satellite S_mAnd S_lData transmission variable in the t-th time slot, if α_m,l,t1 denotes a satellite S_mTransmitting data to satellite S in the tth time slot_lOtherwise, α_m,l,t＝0。

5. The method of claim 4, wherein the method further comprises: in the step S3, modeling the ground stationThe joint variables specifically include: let x_m,k,tRepresenting a satellite S_mWith ground station V_kAssociated variable in the t-th time slot, if x_m,k,t1 denotes a satellite S_mWith ground station V_kIn the t-th time slot, otherwise, x_m,k,t＝0。

6. The method of claim 5, wherein the method further comprises: in step S4, the modeling internet of things gateway data cache model and the satellite data cache model specifically include: the method comprises the steps that an Internet of things gateway collects a certain amount of data and caches the data in the Internet of things gateway, and the Internet of things gateway uploads the data to a satellite through an uplink; the satellite offloading the received internet of things gateway to the other satellite or the ground station;

1) the gateway data caching model of the Internet of things is

2) the satellite data caching model is

Wherein the content of the first and second substances,representing a satellite S_mThe total amount of data buffered at the end of the t time slot;as a satellite S_mThe total data amount of the receiving gateway in the t time slot is specifically represented as:

3) The ground station data caching model isWherein the content of the first and second substances,the total amount of data buffered at the end of the t time slot for the ground station.

7. The method of claim 6, wherein the method further comprises: in step S5, the data forwarding restriction conditions among the gateway, the ground station association, and the satellite specifically include:

1) the gateway association constraint is

2) The limiting condition among satellites is

The modeling resource limiting conditions specifically include:

1) gateway G of internet of things_nThe amount of buffered data is limited to

2) Satellite S_mThe amount of buffered data is limited toWherein the content of the first and second substances,

8. The method of claim 7, wherein the method further comprises: the step S6 specifically includes: when the conditions of gateway, ground station association, data forwarding among satellites and resource limitation are met, and the aim of minimizing the maximum transmission delay of the gateway is taken as the target, an association selection strategy is optimized and determined, namely:

wherein the content of the first and second substances,

Technical Field

The invention belongs to the technical field of wireless communication, and relates to a resource scheduling method for a low-earth-orbit satellite system.

Background

The Internet of things (IoT), namely the Internet with all things connected, is a network extending and expanding on the basis of the Internet, and by combining various information sensing devices with the Internet, the interconnection and the intercommunication of people, machines and things at any time and any place can be realized. The Internet of things is widely applied to multiple fields, such as industry, agriculture, environment, traffic, logistics, security and the like, intelligent development of the fields is effectively promoted, and industrial benefits are improved. For part of internet of things applications, the working environment of the internet of things equipment is severe, reliable cellular network coverage is not available, and the data scheduling problem faces huge challenges, so that how to efficiently transmit the internet of things equipment data becomes an important research topic.

In the existing research at present, documents provide a data transmission strategy based on low-earth orbit satellite forwarding aiming at the problem of data transmission of the internet of things distributed in remote areas, and provide an online algorithm based on a Lyapunov optimization theory to realize data uploading of the internet of things under the condition that the limitations of the gateway capacity and the satellite capacity of the internet of things are met.

In the existing research, uplink transmission or downlink transmission link of data of the internet of things is considered more, uplink and downlink data transmission of the internet of things is not considered comprehensively, and data transmission delay optimization is considered fully, which may cause that the data transmission performance is severely limited.

Disclosure of Invention

In view of the above, the present invention provides a method for scheduling low-earth-orbit satellite system resources. In the method, the internet of things gateway collects data of the internet of things equipment, the internet of things equipment is successfully unloaded to the ground station through low-earth satellite relay, association selection among the internet of things gateways, satellites and between the satellites and the ground station and resource limitation of the satellites are comprehensively considered, and maximum internet of things gateway transmission delay minimization is effectively achieved, so that fairness among the internet of things gateways is ensured, and system performance is improved.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for scheduling low earth orbit satellite system resources comprises the following steps:

s1: modeling an internet of things gateway association variable;

s2: modeling data forwarding variables among satellites;

s3: modeling a ground station association variable;

s4: modeling an internet of things gateway, a satellite and a ground station data cache model;

s5: modeling an internet of things gateway, ground station association and resource allocation limiting conditions;

s6: and determining a user association and resource scheduling strategy based on the maximum transmission delay minimization of the gateway of the Internet of things.

Optionally, the number of the internet of things gateways is N, the number of the satellites is M, and the number of the ground stations is K; g_nRepresents the nth gateway of the Internet of things, S_mDenotes the m-th satellite, V_kRepresenting the kth ground station, N is more than or equal to 1 and less than or equal to N, M is more than or equal to 1 and less than or equal to M, and K is more than or equal to 1 and less than or equal to K.

Optionally, in step S1, the modeling internet of things gateway association selection variable specifically includes: let u_n,m,t∈ {0,1} is gateway G of Internet of things_nAnd satellite S_mAssociated variable in the t-th time slot, if u_n,m,t1, denotes the internet of things gateway G_nAnd satellite S_mAssociating in the t-th time slot, otherwise u_n,m,t＝0。

Optionally, in the step S2, modeling the data transmission variable between satellites specifically includes signaling α_m,l,t∈ {0,1} denotes satellite S_mAnd S_lData transmission variable in the t-th time slot, if α_m,l,t1 denotes a satellite S_mTransmitting data to satellite S in the tth time slot_lOtherwise, α_m,l,t＝0。

Optionally, in step S3, the modeling of the ground station associated variable specifically includes: let x_m,k,tRepresenting a satellite S_mWith ground station V_kAssociated variable in the t-th time slot, if x_m,k,t1 denotes a satellite S_mWith ground station V_kIn the t-th time slot, otherwise, x_m,k,t＝0。

Optionally, in step S4, the modeling internet of things gateway data caching model and the satellite data caching model specifically include: the method comprises the steps that an Internet of things gateway collects a certain amount of data and caches the data in the Internet of things gateway, and the Internet of things gateway uploads the data to a satellite through an uplink; the satellite offloading the received internet of things gateway to the other satellite or the ground station;

1) internet of things gateway data caching modelIs composed ofWherein the content of the first and second substances,is a gateway G_nThe total amount of data buffered at the end of the t-th slot,

is a gateway G of the Internet of things_nThe total amount of data to be transmitted is collected, tau is the length of a unit time slot,is a gateway G of the Internet of things_nT th₀Time slot upload of data to satellite S_mThe rate of the speed of the one or more sensors,the concrete expression is as follows:

wherein p is_nIs a gateway G_nThe transmission power of the transmitter,

as a satellite S_mThe bandwidth of the channel with the gateway,

is at the t₀Time slot gateway G_nTransmitting data to satellite S_mCorresponding channel gain, σ²Is the channel noise power;

2) the satellite data caching model is

Wherein the content of the first and second substances,representing a satellite S_mThe total amount of data buffered at the end of the t time slot;as a satellite S_mThe total data amount of the receiving gateway in the t time slot is specifically represented as:as a satellite S_mThe total amount of data received from other satellites in the t time slot is specifically represented as:wherein the content of the first and second substances,

as a satellite S_mAnd satellite S_lThe transmission rate between the two is specifically represented as:wherein, g_rGain of satellite receiving antenna, g_tTransmitting antenna gain, p, for the satellite_lAs a satellite S_lThe transmission power of the transmitted data to the other satellites,

as a satellite S_mAnd satellite S_lFree space loss of the channel between, k_sIs the Boltzmann constant, T_sFor system thermal noise temperature, E_bEnergy consumed for each bit of data, N₀Is the power spectral density;as a satellite S_mThe total amount of data transmitted to other satellites in the t time slot is specifically expressed as:

as a satellite S_mThe total amount of data transmitted to the ground station at time slot t, specifically expressed as

Wherein the content of the first and second substances,as a satellite S_mSending data to ground station V_kThe rate of (d) is specifically expressed as:wherein the content of the first and second substances,as a satellite S_mTransmitting data to ground station power, h_m,k,tFor the t time slot satellite S_mWith ground station V_kInter-channel gain;

3) the ground station data caching model is

Wherein the content of the first and second substances,the total amount of data buffered at the end of the t time slot for the ground station.

Optionally, in step S5, the data forwarding restriction conditions among the gateway, the ground station association, and the satellite specifically include:

1) the gateway association constraint is

2) The limiting condition among satellites is

The limitation of the satellite and the ground station is

The modeling resource limiting conditions specifically include:

1) gateway G of internet of things_nThe amount of buffered data is limited to

2) Satellite S_mThe amount of buffered data is limited to

Wherein the content of the first and second substances,denotes S_mSatellite maximum buffer capacity.

Optionally, the step S6 specifically includes: when the conditions of gateway, ground station association, data forwarding among satellites and resource limitation are met, and the aim of minimizing the maximum transmission delay of the gateway is taken as the target, an association selection strategy is optimized and determined, namely:

wherein the content of the first and second substances,respectively represent optimized u_n,m,t、α_m,l,t、x_m,k,tT represents the maximum time delay required for the gateway data to be transmitted to the ground station, wherein,

the invention has the beneficial effects that: according to the invention, the fairness among users is ensured and the user experience is improved by comprehensively considering the gateway of the Internet of things, the association selection between the satellite and the ground station and the resource scheduling.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of a low earth orbit satellite Internet of things system scenario;

FIG. 2 is a schematic flow chart of the method of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

As shown in fig. 1, in the method for scheduling resources of the low-earth satellite internet of things system, channel quality between a satellite and a ground station is considered according to channel quality difference between the internet of things and the satellite, so that an internet of things gateway can select different associated satellites, and data is unloaded to the ground station through a relay, thereby improving the overall system performance.

Fig. 2 is a schematic flow chart of the method of the present invention, and as shown in fig. 2, the method of the present invention specifically includes the following steps:

1. gateway association variable of modeling Internet of things

Let u_n,m,t∈ {0,1} is gateway G of Internet of things_nAnd satellite S_mAssociated variable in the t-th time slot, if u_n,m,t1, denotes the internet of things gateway G_nAnd satellite S_mAssociating in the t-th time slot, otherwise u_n,m,t＝0。

2. Modeling data transfer variable between satellites

Let α_m,l,t∈ {0,1} denotes satellite S_mAnd S_lData transmission variable in the t-th time slot, if α_m,l,t1 denotes a satellite S_mTransmitting data to satellite S in the tth time slot_lOtherwise, α_m,l,t＝0。

3. Modeling ground station associated variables

Let x_m,k,tRepresenting a satellite S_mWith ground station V_kAssociated variable in the t-th time slot, if x_m,k,t1 denotes a satellite S_mWith ground station V_kIn the t-th time slot, otherwise, x_m,k,t＝0。

4. Modeling Internet of things gateway, satellite and ground station data caching model

The method comprises the steps that an Internet of things gateway collects a certain amount of data and caches the data in the Internet of things gateway, and the Internet of things gateway uploads the data to a satellite through an uplink; the satellite offloads the received internet of things gateway to the other satellite or the ground station.

1) The gateway data caching model of the Internet of things isWherein the content of the first and second substances,is a gateway G_nThe total amount of data buffered at the end of the t-th slot,is a gateway G of the Internet of things_nThe total amount of data to be transmitted is collected, tau is the length of a unit time slot,is a gateway G of the Internet of things_nT th₀Time slot upload of data to satellite S_mThe rate of the speed of the one or more sensors,the concrete expression is as follows:wherein p is_nIs a gateway G_nThe transmission power of the transmitter,as a satellite S_mThe bandwidth of the channel with the gateway,is at the t₀Time slot gateway G_nTransmitting data to satellite S_mCorresponding channel gain, σ²Is the channel noise power;

2) the satellite data caching model is

Wherein the content of the first and second substances,

representing a satellite S_mThe total amount of data buffered at the end of the t time slot;as a satellite S_mThe total data amount of the receiving gateway in the t time slot is specifically represented as:as a satellite S_mThe total amount of data received from other satellites in the t time slot is specifically represented as:

wherein the content of the first and second substances,as a satellite S_mAnd satellite S_lThe transmission rate between the two is specifically represented as:wherein, g_rGain of satellite receiving antenna, g_tTransmitting antenna gain, p, for the satellite_lAs a satellite S_lThe transmission power of the transmitted data to the other satellites,

as a satellite S_mAnd satellite S_lFree space loss of the channel between, k_sIs the Boltzmann constant, T_sFor system thermal noise temperature, E_bEnergy consumed for each bit of data, N₀Is the power spectral density;as a satellite S_mThe total amount of data transmitted to other satellites in the t time slot is specifically expressed as

As a satellite S_mThe total amount of data transmitted to the ground station at time slot t, specifically expressed asWherein the content of the first and second substances,as a satellite S_mSending data to ground station V_kThe rate of (d) is specifically expressed as:wherein the content of the first and second substances,as a satellite S_mTransmitting data to ground station power, h_m,k,tFor the t time slot satellite S_mWith ground station V_kInter-channel gain.

3) The ground station data caching model is

Wherein the content of the first and second substances,

the total amount of data buffered at the end of the t time slot for the ground station.

5. Modeling Internet of things gateway, ground station association and resource allocation limiting condition

The data forwarding limiting conditions of the gateway, the ground station association and the satellite specifically include:

1) the gateway association constraint is

2) The limiting condition among satellites is

The limitation of the satellite and the ground station is

The modeling resource limiting conditions specifically include:

1) gateway G of internet of things_nThe amount of buffered data is limited to

2) Satellite S_mThe amount of buffered data is limited toWherein the content of the first and second substances,

denotes S_mMaximum buffer capacity of the satellite;

6. determining user association and resource scheduling strategy based on maximum time delay minimization of internet of things gateway transmission

When the conditions of gateway, ground station association, data forwarding among satellites and resource limitation are met, and the aim of minimizing the maximum transmission delay of the gateway is taken as the target, an association selection strategy is optimized and determined, namely:

wherein the content of the first and second substances,

respectively represent optimized u_n,m,t、α_m,l,t、x_m,k,tT represents the maximum time delay required for the gateway data to be transmitted to the ground station, wherein,

finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.