阅读说明：本技术 基于跳波束场景下卫星移动终端的切换方法 (Switching method of satellite mobile terminal based on beam hopping scene ) 是由 张晨 潘宏宇 张更新 于 2021-07-30 设计创作，主要内容包括：本申请涉及一种基于跳波束场景下卫星移动终端的切换方法。该方法包括：获取终端的信道保持时间,分析出终端的新呼叫平均信道保持时间和切换呼叫信道保持时间,终端随机分布在每一个簇内,且切换请求和新连接请求到达率为独立的泊松过程,得到新连接请求到达率,分析出切换请求到达率,根据切换请求到达率和信道保持时间,分析出终端在波束下的平均连接时间,根据概率密度函数,分析得到新连接阻塞率和所有时隙被占用的概率；根据最大排队时间内未释放时隙的概率,终端在重叠区域内一直保持活跃连接的概率得到切换失败率；当切换失败率小于等于门限时,若收敛,输出切换失败率和新连接阻塞率,降低了高速终端的切换失败率。(The application relates to a switching method of a satellite mobile terminal based on a beam hopping scene. The method comprises the following steps: acquiring channel holding time of a terminal, analyzing new call average channel holding time and switching call channel holding time of the terminal, randomly distributing the terminal in each cluster, obtaining new connection request arrival rate by taking a switching request and a new connection request arrival rate as independent poisson processes, analyzing the switching request arrival rate, analyzing the average connection time of the terminal under a wave beam according to the switching request arrival rate and the channel holding time, and analyzing and obtaining new connection blocking rate and the probability of all occupied time slots according to a probability density function; according to the probability of unreleased time slots within the maximum queuing time, the probability that the terminal keeps active connection in the overlapping area all the time obtains the switching failure rate; when the switching failure rate is less than or equal to the threshold, if the switching failure rate and the new connection blocking rate are converged, the switching failure rate of the high-speed terminal is reduced.)

1. A switching method of a satellite mobile terminal based on a beam hopping scene is characterized by comprising the following steps:

step 1: obtaining channel holding time T of terminal_hold；

Step 2: analyzing the average channel holding time of the new call of the terminal through the random distribution of the initial time of the terminalAnd handover call channel hold time

And step 3: the terminals are randomly distributed in each cluster, and the arrival rates of the switching request and the new connection request are independent in the Poisson process, so that the new connection request arrival rate is lambda_new，iAnalyzing the arrival rate of the switching request lambda_handover，i；

And 4, step 4: root of herbaceous plantAccording to the arrival rate of the switching request lambda_handover，iAnd said channel hold time T_holdAnalyzing the average connection time of the terminal under the wave beam

And 5: setting occupied time slot in cluster as C, defining f_C(z) normalizing for the probability density function of time slot C;

step 6: according to the probability density function f_C(z) analyzing to obtain a new connection blocking rate P_nbAnd probability P that all time slots are occupied_all；

And 7: according to the probability P of unreleased time slot in the maximum queuing time_i ^occupiedProbability that the terminal keeps active connection all the time in the overlapping areaObtaining a handover failure rate P_hf；

And 8: when the handover failure rate P_hfGreater than a thresholdIncreasing the number of reserved time slots, and returning to the step 5;

and step 9: when the handover failure rate P_hfLess than or equal to the thresholdAnd if the convergence is reached, outputting the switching failure rate and the new connection blocking rate, otherwise, repeating the step 3.

2. The method of claim 1, wherein obtaining the channel hold time T of the terminal_holdThe formula of (1) is:

T_hold＝{T_res，T_un}

wherein, T_resIs the arrival waveTime interval between the instant of a bit and the instant of arrival at the boundary of adjacent wave bits, T_unIs an unimpeded connection time, T_unObey an exponential distribution.

3. The method of claim 1, wherein analyzing the average channel hold time for the terminal for new callsAnd handover call channel hold timeThe formula of (1) is:

wherein, tau is average connection time, e is natural constant, R_max，iThe time required for a terminal to pass one wave bit, i denotes the terminal type, i ═ a, for airplane, i ═ t, for train,indicating the new call average channel hold time of the terminal,indicating the handover call average channel hold time of the terminal.

4. Method according to claim 1, characterized in that the handover request arrival rate λ is analyzed_handover，iThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfIndicates the probability of handover failure, P_new，iIndicating the probability that the terminal needs to be handed over when a new call is made, P_handover，iIndicates the probability, lambda, that the terminal needs to be handed over in a handover call_new，iIndicating the new connection request arrival rate, λ_handover，iIndicating the handover request arrival rate.

5. The method of claim 1, wherein the average connection time of the terminal under a beam is analyzedThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfThe probability of a handover failure is indicated,indicating the new call average channel hold time of the terminal,indicating the average channel holding time, lambda, of the handover call of the terminal_new，iIndicating the new connection request arrival rate, λ_handover，iIndicating the handover request arrival rate.

6. Method according to claim 1, characterized in that the probability density function f of the time slot C is_C(z) is:

wherein, otherwise means z > threshold_j-1，threshold_jThreshold, λ, representing each connection type_jAn arrival rate of the connection type j is represented by 1,2,3,4, which respectively represent a train new connection request, an airplane new connection request, a train switching request, an airplane switching request, and Δ_j(z) represents the identification bit, takes values of 0 and 1, z represents the number of occupied time slots, and takes values in the range of 1,2 … … 140, when j is 1,3, tau_jAverage connection time of train when j is 2,4, tau is terminal type_jFor an average connection time with the terminal type being an airplane, since the train and the airplane share the same time slot resources, a distinction is made between the connection types, then Δ_new(j＝1，2)，Δ_handover(j＝3，4)，threshold_new(j＝1，2)，threshold_handover(j＝3，4)。

7. Method according to claim 1, characterised in that said new connection blocking rate P_nbAnd probability P that all time slots are occupied_allThe analytical formula of (a) is:

wherein, Delta_new(z-1) denotes a new connection request identification bit, Δ_handover(z-1) denotes a handover request identification bit, and W denotes a window length of one periodic slot.

8. The method of claim 1, wherein the method is performed in a batch processAccording to the probability P of unreleased time slot in the maximum queuing time_i ^occupiedProbability that the terminal keeps active connection all the time in the overlapping areaObtaining a handover failure rate P_hfThe method comprises the following steps:

through tau_i，Obtaining probability that terminal keeps active connection in overlapping regionThe formula is as follows:

wherein the content of the first and second substances,indicating that the handover queue threshold value, the algorithm is different,take different values, τ_iRepresents the inverse of the average connection time of the terminal;

by passingObtaining the probability P of unreleased time slot in the maximum queuing time_i ^occupiedThe formula is as follows:

wherein the content of the first and second substances,representing the ratio of the number of time slots occupied by the aircraft,represents the ratio of the number of time slots occupied by the train, and

by P_i ^occupied，P_iObtaining a handover failure rate P_hf：

Wherein, P_iProbability that the terminal requesting the handover is the i-th class terminal, a denotes an airplane and t denotes a train.

9. The method of claim 1, wherein the handover failure rate P is determined based on the determined handover failure rate_hfGreater than a thresholdAnd (5) increasing the number of the reserved time slots, and returning to the step of the step (5), wherein the step comprises the following steps:

will switch failure rate P_hfAnd a failure rate thresholdComparing;

if it isThe time slot reservation number K equals K +1, and S5 is repeated;

otherwise, step 9 is executed.

Technical Field

The application relates to the technical field of satellite communication, in particular to a switching method of a satellite mobile terminal based on a beam hopping scene.

Background

The basic idea of the beam hopping technique is to use a time slicing technique, and not all the wave bits but only a part of the wave bits are lighted for operation in the same time slice. Compared with the traditional multi-beam satellite system, the new idea can better meet the application scene of unbalanced service requirements. On the basis of the technology, in order to ensure the continuity of the communication between the wave bits of the high-speed mobile terminal, it is important to research a feasible beam switching algorithm.

Currently, the commonly used beam switching technology is basically under a multi-beam scene, and includes a hard switching algorithm based on received signal strength, a switching mechanism based on geographical location, and the like. The speed factor is not considered based on the switching mechanism of the geographic position, and the principle of switching first is followed, so that the method has great limitation; hard handoff based on received signal strength this algorithm does not take into account location considerations and hard handoff algorithms are prone to communication disruptions.

Therefore, the current beam switching technology makes the failure rate of high-speed terminal switching higher.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a handover method for a satellite mobile terminal in a beam hopping-based scenario, which can reduce the failure rate of high-speed terminal handover.

A switching method of a satellite mobile terminal based on a beam hopping scene comprises the following steps:

step 1: obtaining channel holding time T of terminal_hold；

Step 2: analyzing the average channel holding time of the new call of the terminal through the random distribution of the initial time of the terminalAnd handover call channel hold time

And step 3: the terminals are randomly distributed in each cluster, and the arrival rates of the switching request and the new connection request are independent in the Poisson process, so that the new connection request arrival rate is lambda_new，iAnalyzing the arrival rate of the switching request lambda_handover，i；

And 4, step 4: according to the arrival rate of the switching request lambda_handover，iAnd said channel hold time T_holdAnalyzing the average connection time of the terminal under the wave beam

And 5: setting occupied time slot in cluster as C, defining f_C(z) normalizing for the probability density function of time slot C;

step 6: according to the probability density function f_C(z) analyzing to obtain a new connection blocking rate P_nbAnd probability P that all time slots are occupied_all；

And 7: according to the probability P of unreleased time slot in the maximum queuing time_i ^occupiedProbability that the terminal keeps active connection all the time in the overlapping areaObtaining a handover failure rate P_hf；

And 8: when the handover failure rate P_hfGreater than a thresholdIncreasing the number of reserved time slots, and returning to the step 5;

and step 9: when the handover failure rate P_hfLess than or equal to the thresholdAnd if the convergence is reached, outputting the switching failure rate and the new connection blocking rate, otherwise, repeating the step 3.

In one embodiment, the channel holding time T of the terminal is obtained_holdThe formula of (1) is:

T_hold＝{T_res,T_un}

wherein, T_resIs the time interval between the instant of arrival at a wave position and the instant of arrival at the boundary of adjacent wave positions, T_unIs an unimpeded connection time, T_unObey an exponential distribution.

In one embodiment, the average channel holding time of the new call of the terminal is analyzedAnd handover call channel hold timeThe formula of (1) is:

wherein, tau is average connection time, e is natural constant, R_max,iThe time required for a terminal to pass one wave bit, i denotes the terminal type, i ═ a, for airplane, i ═ t, for train,indicating the new call average channel hold time of the terminal,indicating the handover call average channel hold time of the terminal.

In one embodiment, the handover request arrival rate λ is analyzed_handover,iThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfIndicates the probability of handover failure, P_new,iIndicating the probability that the terminal needs to be handed over when a new call is made, P_handover,iIndicates the probability, lambda, that the terminal needs to be handed over in a handover call_new,iIndicating the new connection request arrival rate, λ_handover,iIndicating the handover request arrival rate.

In one embodiment, the average connection time of the terminal under the beam is analyzedThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfThe probability of a handover failure is indicated,indicating the new call average channel hold time of the terminal,indicating the average channel holding time, lambda, of the handover call of the terminal_new,iIndicating the new connection request arrival rate, λ_handover,iIndicating the handover request arrival rate.

In one embodiment, the probability density function f of the time slot C_C(z) is:

wherein otherwise represents z>threshold_j-1，threshold_jThreshold, λ, representing each connection type_jAn arrival rate of the connection type j is represented by 1,2,3,4, which respectively represent a train new connection request, an airplane new connection request, a train switching request, an airplane switching request, and Δ_j(z) represents the identification bit, takes values of 0 and 1, z represents the number of occupied time slots, and takes values in the range of 1,2 … … 140, when j is 1,3, tau_jAverage connection time of train when j is 2,4, tau is terminal type_jFor an average connection time with the terminal type being an airplane, since the train and the airplane share the same time slot resources, a distinction is made between the connection types, then Δ_new(j＝1,2)，Δ_handover(j＝3,4)，threshold_new(j＝1,2)，threshold_handover(j＝3,4)。

In one embodiment, the new connection blocking rate P_nbAnd probability P that all time slots are occupied_allThe analytical formula of (a) is:

wherein, Delta_new(z-1) denotes a new connection request identification bit, Δ_handover(z-1) denotes a handover request identification bit, and W denotes a window length of one periodic slot.

In one embodiment, the method is based on the probability P of unreleased time slots within the maximum queuing time_i ^occupiedProbability that the terminal keeps active connection all the time in the overlapping areaObtaining a handover failure rate P_hfThe method comprises the following steps:

through tau_i，Obtaining probability that terminal keeps active connection in overlapping regionThe formula is as follows:

wherein the content of the first and second substances,indicating that the handover queue threshold value, the algorithm is different,take different values, τ_iRepresents the inverse of the average connection time of the terminal;

by passingObtaining the probability P of unreleased time slot in the maximum queuing time_i ^occupiedThe formula is as follows:

wherein the content of the first and second substances,representing the ratio of the number of time slots occupied by the aircraft,represents the ratio of the number of time slots occupied by the train, and

by P_i ^occupied，P_iObtaining a handover failure rate P_hf：

Wherein, P_iProbability that the terminal requesting the handover is the i-th class terminal, a denotes an airplane and t denotes a train.

In one embodiment, the switching failure rate P is_hfGreater than a thresholdAnd (5) increasing the number of the reserved time slots, and returning to the step of the step (5), wherein the step comprises the following steps:

will switch failure rate P_hfAnd a failure rate thresholdComparing;

if it isThe time slot reservation number K equals K +1, and S5 is repeated;

otherwise, step 9 is executed.

According to the switching method of the satellite mobile terminal based on the beam hopping scene, the new call average channel holding time and the switching call channel holding time of the terminal are analyzed through acquiring the channel holding time of the terminal and through the random distribution of the initial time of the terminal, the terminal is randomly distributed in each cluster, the switching request and the new connection request arrival rate are independent poisson processes, the new connection request arrival rate is obtained, the switching request arrival rate is analyzed, the average connection time of the terminal under the beam is analyzed according to the switching request arrival rate and the channel holding time, and the new connection blocking rate and the probability that all time slots are occupied are analyzed according to the probability density function; according to the probability of unreleased time slots within the maximum queuing time, the probability that the terminal keeps active connection in the overlapping area all the time obtains the switching failure rate; and when the switching failure rate is less than or equal to the threshold, judging the convergence, and if the switching failure rate is converged, outputting the switching failure rate and the new connection blocking rate, thereby reducing the switching failure rate of the high-speed terminal.

Drawings

FIG. 1 is a flowchart illustrating a handover method of a satellite mobile terminal in a beam hopping scenario according to an embodiment;

FIG. 2 is a diagram of a beam hopping system model of a simulation process;

FIG. 3 shows the handover failure rates of two handover algorithms in the simulation process under two scenarios;

fig. 4 shows the handover failure rates of two handover algorithms in the simulation process under two scenarios.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In one embodiment, as shown in fig. 1, a method for handover of a satellite mobile terminal in a beam hopping scenario is provided, which includes the following steps:

step 1: obtaining channel holding time T of terminal_hold；

Step 2: analyzing the average channel holding time of the new call of the terminal through the random distribution of the initial time of the terminalAnd handover call channel hold time

And step 3: terminals are randomly distributed in each cluster, and the arrival rate of the switching request and the new connection request is independent in the poisson process, so that the new connection request arrival rate is lambda_new,iAnalyzing the arrival rate of the switching request lambda_handover,i；

And 4, step 4: according to the handover request arrival rate lambda_handover,iAnd channel hold time T_holdAnalyzing the average connection time of the terminal under the beam

And 5: setting occupied time slot in cluster as C, defining f_C(z) normalizing for the probability density function of time slot C;

step 6: according to a probability density function f_C(z) analyzing to obtain a new connection blocking rate P_nbAnd probability P that all time slots are occupied_all；

And 7: according to the probability P of unreleased time slot in the maximum queuing time_i ^occupiedProbability of terminal remaining actively connected at all times in overlapping areaObtaining a handover failure rate P_hf；

And 8: when handover failure rate P_hfGreater than a thresholdIncreasing the number of reserved time slots, and returning to the step 5;

and step 9: when handover failure rate P_hfLess than or equal to the thresholdAnd if the convergence is reached, outputting the switching failure rate and the new connection blocking rate, otherwise, repeating the step 3.

According to the switching method of the satellite mobile terminal based on the beam hopping scene, the new call average channel holding time and the switching call channel holding time of the terminal are analyzed through acquiring the channel holding time of the terminal and through the random distribution of the initial time of the terminal, the terminal is randomly distributed in each cluster, the switching request and the new connection request arrival rate are independent poisson processes, the new connection request arrival rate is obtained, the switching request arrival rate is analyzed, the average connection time of the terminal under the beam is analyzed according to the switching request arrival rate and the channel holding time, and the new connection blocking rate and the probability that all time slots are occupied are analyzed according to a probability density function; according to the probability of unreleased time slots within the maximum queuing time, the probability that the terminal keeps active connection in the overlapping area all the time obtains the switching failure rate; and when the switching failure rate is less than or equal to the threshold, judging the convergence, and if the convergence is reached, outputting the switching failure rate and the new connection blocking rate, thereby reducing the switching failure rate of the high-speed terminal.

In one embodiment, the channel holding time T of the terminal is obtained_holdThe formula of (1) is:

T_hold＝{T_res，T_un}

wherein, T_resIs the time interval between the instant of arrival at a wave position and the instant of arrival at the boundary of adjacent wave positions, T_unIs an unimpeded connection time, T_unObey an exponential distribution.

In one embodiment, the average channel hold time for a new call for a terminal is analyzedAnd handover call channel hold timeThe formula of (1) is:

wherein, tau is average connection time, e is natural constant, R_max,iThe time required for a terminal to pass one wave bit, i denotes the terminal type, i ═ a, for airplane, i ═ t, for train,indicating the new call average channel hold time of the terminal,indicating the handover call average channel hold time of the terminal.

In one embodiment, the handover request arrival rate λ is analyzed_handover,iThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfIndicates the probability of handover failure, P_new,iIndicating the probability that the terminal needs to be handed over when a new call is made, P_handover,iIndicates the probability, lambda, that the terminal needs to be handed over in a handover call_new,iIndicating the new connection request arrival rate, λ_handover,iIndicating the handover request arrival rate.

In one embodiment, the average connection time of the terminal under the beam is analyzedThe formula of (1) is:

wherein, P_nbIndicates the new connection blocking rate, P_hfThe probability of a handover failure is indicated,indicating the new call average channel hold time of the terminal,indicating the average channel holding time, lambda, of the handover call of the terminal_new,iIndicating the new connection request arrival rate, λ_handover,iIndicating the handover request arrival rate.

In one embodiment, the probability density function f of time slot C_C(z) is:

wherein otherwise represents z>threshold_j-1，threshold_jThreshold, λ, representing each connection type_jAn arrival rate of the connection type j is represented by 1,2,3,4, which respectively represent a train new connection request, an airplane new connection request, a train switching request, an airplane switching request, and Δ_j(z) represents the identification bit, takes values of 0 and 1, z represents the number of occupied time slots, and takes values in the range of 1,2 … … 140, when j is 1,3, tau_jAverage connection time of train when j is 2,4, tau is terminal type_jFor an average connection time with the terminal type being an airplane, since the train and the airplane share the same time slot resources, a distinction is made between the connection types, then Δ_new(j＝1,2)，Δ_handover(j＝3,4)，threshold_new(j＝1,2)，threshold_handover(j＝3，4)。

In one embodiment, the new connection blocking rate P_nbAnd probability P that all time slots are occupied_allThe analytical formula of (a) is:

wherein, Delta_new(z-1) denotes a new connection request identification bit, Δ_handover(z-1) denotes a handover request identification bit, and W denotes a window length of one periodic slot.

At one endIn one embodiment, the probability P of unreleased time slots within the maximum queuing time is used_i ^occupiedProbability of terminal remaining actively connected at all times in overlapping areaObtaining a handover failure rate P_hfThe method comprises the following steps:

through tau_i，Obtaining probability that terminal keeps active connection in overlapping regionThe formula is as follows:

wherein the content of the first and second substances,indicating that the handover queue threshold value, the algorithm is different,take different values, τ_iRepresents the inverse of the average connection time of the terminal;

by passingObtaining the probability P of unreleased time slot in the maximum queuing time_i ^occupiedThe formula is as follows:

wherein the content of the first and second substances,representing the ratio of the number of time slots occupied by the aircraftThe value of the one or more of the one,represents the ratio of the number of time slots occupied by the train, and

by P_i ^occupied，P_iObtaining a handover failure rate P_hf：

Wherein, P_iProbability that the terminal requesting the handover is the i-th class terminal, a denotes an airplane and t denotes a train.

In one embodiment, when the handover fails the rate P_hfGreater than a thresholdAnd (5) increasing the number of the reserved time slots, and returning to the step of the step (5), wherein the step comprises the following steps: will switch failure rate P_hfAnd a failure rate thresholdComparing; if it isThe time slot reservation number K equals K +1, and S5 is repeated; otherwise, step 9 is executed.

According to the switching method of the satellite mobile terminal based on the beam hopping scene, the time slot resources are prepared for the terminal with high urgency by queuing the urgency of different terminals, and the switching failure rate is obtained. When the switching failure rate is higher than the set threshold, the reserved number of time slots is dynamically increased, so that the switching failure rate of the high-speed terminal between the wave beams is reduced, and the performance of the system is improved.

The effect of the present application can be further verified by the following simulation:

1. an experimental scene is as follows:

in this model, the GEO satellite altitude 35786KM and the beam radius is 200 KM. All the wave bits are divided into 3 clusters, each cluster includes 7 wave bits, and the arrival rate of the terminal in one wave bit is from 0 to 20. And the time slot window of each cluster is W, and each terminal needs at least 1 time slot resource for successful new connection or successful switching. For all types of terminals, the connection time follows an exponential distribution with a mean value of 1 h. Under the mechanism based on the time remaining, it is,

2. experimental contents and results:

in order to verify the performance of the invention, a system model diagram as shown in fig. 2 is adopted, and simulation results are shown in fig. 3 and fig. 4.

Compared with other algorithms, the dynamic time slot algorithm based on the residual time greatly reduces the switching failure rate of the mobile terminal. As can be seen from the simulation diagrams of fig. 3 and 4, the higher the arrival rate, the more the dynamic reserved slot algorithm based on the remaining time has a significant improvement on the handover failure rate. Because the resources in the beam are relatively sufficient under the condition of low arrival rate, and the time slot resources can not meet the requirements under the condition of higher arrival rate, the switching failure rate and the new connection blocking rate are gradually increased; in order to make the switching failure rate P_hfLess than a set threshold_PhfAs the terminal arrival rate increases, a greater number of slots is reserved.

It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.