Dynamic spectrum allocation method based on dual spectrum pools

Abstract

The present invention provides a dynamic spectrum allocation method based on a dual spectrum pool, which includes: determining relevant parameters for dynamic spectrum allocation, determining the allocation of newly arrived primary users based on the relevant parameters, constructing a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy, determining the allocation of newly arrived first-class secondary users and second-class secondary users, solving the blocking rate and call drop rate of the first-class secondary users and the second-class secondary users and the throughput of the primary users, the first-class secondary users and the second-class secondary users, compromising the performance indicators of various systems, constructing a system benefit function, and obtaining the CP channel number and RP channel number with the maximum system benefit and the optimal secondary user arrival rate. The present invention constructs a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy for two types of secondary users, obtains the relevant performance indicators of the steady-state secondary users to evaluate the system performance, and has better applicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of cognitive radio dynamic spectrum allocation, and in particular to a dynamic spectrum allocation method based on dual spectrum pools. Background Art

[0002] In cognitive wireless networks, the shortage of spectrum resources has become an important bottleneck restricting the development of more wireless technologies. This shortage of spectrum resources has been obvious in the 4G era, and will be more prominent in the 5G era. The spectrum resources allocated by the traditional static spectrum allocation method are at a relatively low utilization level. According to the statistics of the probability of spectrum occupation in six districts by the National Radio Network Research Testbed (NRNRT) project in the United States, the probability of spectrum occupation is less than 6%. The lack of spectrum resources is not only due to the physical scarcity of frequency bands, but more to the inflexible spectrum allocation and inadequate management policies. How to alleviate the shortage of spectrum resources has become an urgent problem to be solved.

[0003] At this time, cognitive radio technology (CR) came into being. CR was originally proposed by Dr. Mitola on the basis of software defined radio technology (SDR). After that, Goldsmith, Haykin and others expanded the definition and connotation of cognitive radio technology to a certain extent. Generally, cognitive radio can be considered as an intelligent non-spectrum authorized wireless communication system. The general idea is that the cognitive radio system can perceive the electromagnetic environment and its own needs around the system, and summarize the corresponding cognitive information through learning and reasoning. If it is found that there is a spectrum that is not used by the primary user at this time, that is, spectrum holes, cognitive radio can use dynamic spectrum allocation to allow secondary users to access the spectrum opportunistically, and adjust the system transmission strategy in real time and intelligently according to the perceived and inferred cognitive information. By "reusing" the authorized spectrum resources, the problem of spectrum resource shortage is fundamentally solved. Many studies only focus on the service quality of primary users, conduct modeling and evaluation for them, and propose many performance optimization strategies. When conducting strategy modeling and performance analysis, most literature usually assumes that the spectrum perception results of secondary users are ideal. However, in actual situations, the impact of spectrum perception errors caused by missed detection and false alarms of secondary users on system performance cannot be ignored. On the other hand, existing literature on non-ideal perception dynamic spectrum allocation strategies lacks perception of secondary users and ignores the situation where collisions and dropped calls occur between two secondary users. So far, there is a lack of research on dynamic spectrum allocation strategies that comprehensively consider the non-ideal perception of secondary users. Therefore, based on the above research background, it is urgent and necessary to seek a dynamic spectrum allocation method based on dual spectrum pools to ensure the service quality of primary users while taking into account the non-ideality of secondary user perception. Summary of the invention

[0004] In view of the defects in the above-mentioned prior art, the present invention proposes a dynamic spectrum allocation method based on dual spectrum pools. RP stands for Random Preemptive and CP stands for Collaborative Preemptive. The method includes determining relevant parameters for dynamic spectrum allocation, determining the allocation of newly arrived primary users based on the relevant parameters, constructing a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance collaborative access strategy, determining the allocation of newly arrived first-class secondary users and second-class secondary users, solving the blocking rate and call drop rate of the first-class secondary users and the second-class secondary users, and the throughput of the primary users, the first-class secondary users and the second-class secondary users, compromising the performance indicators of various systems, constructing a system benefit function, and obtaining the CP channel number and RP channel number with the maximum system benefit and the optimal secondary user arrival rate. The present invention constructs a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance collaborative access strategy for two types of secondary users, obtains the relevant performance indicators of the next secondary users in the steady state to evaluate the system performance, and has better applicability.

[0005] The present invention provides a dynamic spectrum allocation method based on dual spectrum pools, which comprises the following steps:

[0006] S1. Determine relevant parameters for dynamic spectrum allocation, wherein the relevant parameters include the arrival rate λ1 of the main user in the secondary user classification strategy, the arrival rate λ 21 , the arrival rate of the second-class secondary users λ 22 , the service rate of the main user μ1, the service rate of a type of secondary user μ 21 , the service rate of the second-class secondary users μ 22 , the number of CP and RP channels occupied by the main user i CP ,i RP , the number of CP and RP channels occupied by a type of secondary user j CP ,j RP , the number of CP and RP channels occupied by the second type of secondary users k CP ,k RP And the number of idle channels N of CP and RP CP,IDLE ,N RP,IDLE , the N CP,IDLE ,N RP,IDLE Respectively expressed as:

[0007] N CP,IDLE =γ CP -i CP -j CP -k CP (1)

[0008] N RP,IDLE =γRP -i RP -j RP -k RP (2)

[0009] Among them, γ CP Indicates the number of CP channels; γ RP Indicates the number of RP channels;

[0010] S2. When a primary user arrives at the system, the allocation of the newly arrived primary user is determined based on relevant parameters;

[0011] S3. Construct a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy, determine the allocation of newly arrived first-class secondary users and second-class secondary users, and establish a balance equation to solve the steady-state probability;

[0012] S4, solving the blocking rate and call drop rate of the first-class secondary users and the second-class secondary users;

[0013] S5. Calculate the throughput θ1, θ2, θ3 of the primary user, the first type of secondary user and the second type of secondary user:

[0014]

[0015] θ2=λ 21 (1-β1-α1) (8)

[0016] θ3=λ 22 (1-β2-α2) (9)

[0017] Where β1, β2 represent the blocking rates of the first and second secondary users respectively; α1, α2 represent the call drop rates of the first and second secondary users respectively; π(s) represents the steady-state probability under state s;

[0018] S6. Compromise the performance indicators of various systems and construct the system benefit function R:

[0019] R=r1θ1+r2θ2+r3θ3-r4(1 / μ 21 )(1-β1)-r5(1 / μ 22 )(1-β2)-r6(γ CP +γ RP ) (10)

[0020] Among them, r1 represents the benefit that can be obtained by successfully transmitting a primary user system; r2 represents the benefit that can be obtained by successfully transmitting a first-class secondary user system; r3 represents the benefit that can be obtained by successfully transmitting a second-class secondary user system; r4 and r5 represent the system loss of a first-class secondary user and a second-class secondary user staying in the system for one time slot respectively; r6 represents the loss of one channel provided by the system administrator;

[0021] S7. Use MATLAB to solve and obtain the maximum CP channel number γ of the system benefit function R CP * and the number of RP channels γ RP *.

[0022] Preferably, the step S2 specifically includes the following steps:

[0023] S21, when i RP +j RP +k RP ≤γ RP That is N RP,IDLE ≥0, the newly arrived primary user arrives with probability N RP,IDLE / γ RP -i RP Randomly access an idle RP channel, or with probability j RP / γ RP -i RP Access an RP channel occupied by a class of secondary users, or with probability k RP / γ RP -i RP Access an RP channel occupied by a second-class secondary user;

[0024] S22, when i RP =γ RP And N CP,IDLE When >0, the newly arrived primary user accesses an idle CP channel;

[0025] S23, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP > 0, the newly arrived primary user accesses a CP channel occupied by a second-class secondary user;

[0026] S24, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is NCP,IDLE = 0 and j CP When >0, the newly arrived primary user accesses a CP channel occupied by a type of secondary user;

[0027] S25, when i RP =γ RP And i CP =γ CP When , the newly arrived primary user will be blocked.

[0028] Preferably, the step S3 specifically includes the following steps:

[0029] S31, when a class of secondary users arrives at the system, a random preemptive access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived class of secondary users;

[0030] S311, when N CP,IDLE When >0, a newly arrived secondary user accesses an idle CP channel;

[0031] S312, when i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP > 0, the newly arrived secondary user of type 1 accesses a CP channel occupied by a secondary user of type 2;

[0032] S313, when i CP +j CP =γ CP And i RP +j RP <γ RP When a new type of secondary user arrives with probability N RP,IDLE / γ RP -i RP -j RP Access an idle RP channel, or with probability k RP / γ RP -i RP -j RP Access an RP channel occupied by a second-class secondary user;

[0033] S314, when i CP +j CP =γ CP And i RP +j RP =γ RP When , a newly arrived class of secondary users will be blocked;

[0034] S32, when the second-class secondary user arrives at the system, a conflict avoidance cooperative access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived second-class secondary user;

[0035] S321, when i CP +j CP +k CP <γ CP When , the newly arrived second-class secondary user accesses an idle CP channel;

[0036] S322, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP <γ RP When , the newly arrived second-class secondary user accesses an idle RP channel;

[0037] S323, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP =γ RP When , the newly arrived second-class secondary users will be blocked. The steady-state probability π(s) can be obtained from the equilibrium equation ΠQ=0,Πe=1, where Q represents the transfer rate matrix; e represents the identity matrix and e=[1,1,...,1] T .

[0038] Preferably, the step S5 specifically includes the following steps:

[0039] S41, solve the blocking rates β1 and β2 of the first-class secondary users and the second-class secondary users. For the newly arrived first-class secondary users, they will be blocked when all the channels in the system are occupied by the primary users and the first-class secondary users; for the newly arrived second-class secondary users, they will be blocked when there are no idle channels in the system. β1 and β2 are respectively:

[0040]

[0041]

[0042] S42, solve the call drop rates α1, α2 of the first and second secondary users. For the first secondary user, a new primary user arrives. When the RP channel is not fully occupied by the primary user and j RP >0, or i RP =γ RP , there is no idle CP channel and jCP > 0, the transmission of the first type of secondary users is interrupted by the primary users and they leave the system; for the second type of secondary users, when there is no idle CP channel and k CP >0, or i CP +j CP =γ CP And k RP When >0, the transmission of the second-class secondary user is interrupted by the first-class secondary user and leaves the system. α1 and α2 are:

[0043]

[0044]

[0045] Preferably, the method further includes solving the optimal secondary user arrival rate for maximizing the system benefit function when there are only primary users and secondary users under non-ideal perception, which specifically includes the following steps:

[0046] S81. Assume that missed detection of primary users, missed detection of secondary users and false alarms occur with a certain probability on each channel, which are called missed detection rates p mp , missed detection rate p ms And the false alarm rate p f , set the energy detection threshold τ pu and τ su , and τ pu >τ su , the missed detection rate p mp , missed detection rate p ms and false alarm rate p f The solution is as follows:

[0047]

[0048] in, N represents the number of times the secondary user detects the channel; γ represents the signal-to-noise ratio; represents the noise variance;

[0049] S82. When the secondary user senses that there are no idle CP channels and RP channels, solve the secondary user blocking rate P in state s. block :

[0050]

[0051] S83, solving the call drop rate P of the next type of secondary users in state s drop , the secondary user call drop rate P drop is the proportion of discarded secondary users among all arriving secondary users;

[0052] S84. Solving the secondary user effective throughput η s , the secondary user effective throughput ηs is the number of secondary users that successfully transmit per unit time, and the secondary user call drop rate and secondary user blocking rate under state s are solved:

[0053] η s =λ s (1-P block -P drop ) (16)

[0054] Among them, λ s represents the secondary user arrival rate;

[0055] S85. According to the secondary user effective throughput η s Determine the personal benefit function U ind :

[0056]

[0057] S86. According to the personal benefit function U ind Determine the system benefit function U sys :

[0058] U soc =(1-P block -P drop ) s U ind (18);

[0059] S87. Obtaining system benefit function U sys The optimal secondary user arrival rate when

[0060] Preferably, the step S83 specifically includes the following steps:

[0061] S831. When a secondary user accesses a channel occupied by a primary user or a secondary user, a conflict occurs between the secondary user and the primary user or between the secondary user and the secondary user. At this time, the conflicting secondary user drops the call. The secondary user drop rate under the secondary user access is:

[0062]

[0063] in, They represent the probability that a secondary user mistakenly accesses the CP and RP channels occupied by secondary users and primary users respectively; p0 represents the probability that a secondary user detects that there are no idle channels in the CP channel pool;

[0064] S832. When the primary user seizes the channel occupied by the secondary user, the secondary user correctly senses the arrival of the primary user and withdraws from the current channel. At this time, the secondary user's call drop occurs. The secondary user's call drop rate under the primary user access is:

[0065]

[0066] S833, state s next lower user call drop rate P drop for:

[0067] P drop =p drop_s1 +p drop_s2 (15).

[0068] Compared with the prior art, the technical effects of the present invention are:

[0069] 1. A dynamic spectrum allocation method based on dual spectrum pools designed in the present invention aims at the problems that the growing demand for data transmission, the shortage of existing spectrum resources, and the diversity of secondary users' transmission needs can no longer be met. The secondary users are classified into two categories, and a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy is constructed; the steady-state probability of the equilibrium equation solution model is established to obtain the blocking rate, call drop rate and throughput performance indicators of the first and second categories of secondary users and the third category of users in the steady state.

[0070] 2. The present invention designs a dynamic spectrum allocation method based on dual spectrum pools. Aiming at the non-ideality of spectrum perception by secondary users, a dual energy detection threshold is introduced into the dynamic spectrum allocation strategy. In order to take into account the service quality of primary users and the collision and conflict problems caused by non-ideal perception, a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance collaborative access strategy is constructed. The steady-state probability of the equilibrium equation solution model is established, and the blocking rate, call drop rate and effective throughput of secondary users are used as indicators to evaluate the system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings.

[0072] Figure 1 is a flow chart of a dynamic spectrum allocation method based on dual spectrum pools of the present invention;

[0073] Figure 2 It is a flow chart of the main user arrival of the present invention;

[0074] Figure 3 is a flow chart of arrival of a class of secondary users of the present invention;

[0075] Figure 4 is a flow chart of arrival of a class of secondary users of the present invention;

[0076] Figure 5 is a flow chart of the main user access of the present invention;

[0077] Figure 6 is a flow chart of secondary user access of the present invention;

[0078] Figure 7 It is a simulation diagram of the blocking rate of the second type of secondary users under the secondary user classification of the present invention;

[0079] Figure 8 It is a simulation diagram of call drop rate of two types of secondary users under the secondary user classification of the present invention;

[0080] Fig. 9 It is a simulation diagram of the blocking rate of the secondary user under non-ideal perception with only the primary user and the secondary user of the present invention;

[0081] Fig.10 It is a simulation diagram of the call drop rate of the secondary users under non-ideal perception with only primary users and secondary users according to the present invention. DETAILED DESCRIPTION

[0082] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0083] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0084] Figure 1 The present invention shows a dynamic spectrum allocation method based on dual spectrum pools, which includes the following steps:

[0085] S1. Determine relevant parameters for dynamic spectrum allocation, the relevant parameters including the arrival rate λ1 of the main user in the secondary user classification strategy, the arrival rate λ of a class of secondary users 21 , the arrival rate of the second-class secondary users λ 22 , the service rate of the main user μ1, the service rate of a type of secondary user μ 21 , the service rate of the second-class secondary users μ 22 , the number of CP and RP channels occupied by the main user i CP ,i RP , the number of CP and RP channels occupied by a type of secondary user j CP ,j RP , the number of CP and RP channels occupied by the second type of secondary users k CP ,k RP And the number of idle channels N of CP and RPCP,IDLE ,N RP,IDLE , N CP,IDLE ,N RP,IDLE Respectively expressed as:

[0086] N CP,IDLE =γ CP -i CP -j CP -k CP (1)

[0087] N RP,IDLE =γ RP -i RP -j RP -k RP (2)

[0088] Among them, γ CP Indicates the number of CP channels; γ RP Indicates the number of RP channels.

[0089] S2. When a primary user arrives at the system, the allocation of the newly arrived primary user is determined based on relevant parameters.

[0090] S21, when i RP +j RP +k RP ≤γ RP That is N RP,IDLE ≥0, the newly arrived primary user arrives with probability N RP,IDLE / γ RP -i RP Randomly access an idle RP channel, or with probability j RP / γ RP -i RP Access an RP channel occupied by a class of secondary users, or with probability k RP / γ RP -i RP Access an RP channel occupied by a second-class secondary user.

[0091] S22, when i RP =γ RP And N CP,IDLE When >0, the newly arrived primary user accesses an idle CP channel.

[0092] S23, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP When >0, the newly arrived primary user accesses a CP channel occupied by a second-class secondary user.

[0093] S24, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and j CP When >0, the newly arrived primary user accesses a CP channel occupied by a type of secondary user.

[0094] S25, when i RP =γ RP And i CP =γ CP When , the newly arrived primary user will be blocked.

[0095] Specifically, Figure 2 As shown in the figure, when a new primary user PU arrives at the system, it first accesses the RP channel. If there is a channel in the RP spectrum pool that is not occupied by other primary users, a free channel or a channel occupied by other secondary users is randomly allocated to the newly arrived primary user with equal probability; otherwise, the newly arrived primary user accesses the CP spectrum pool to determine whether there is an free channel. If so, an free CP channel is first allocated to the newly arrived primary user. Otherwise, based on the priority, the newly arrived primary user first occupies the channel being used by the second type of secondary users, and if not, it occupies the channel being used by the first type of secondary users; if both the RP channel and the CP channel are occupied by primary users, the newly arrived primary user is blocked.

[0096] S3. Construct a dynamic spectrum allocation strategy model that combines a random preemptive access strategy with a conflict avoidance cooperative access strategy, determine the allocation of newly arrived first-class secondary users and second-class secondary users, and establish a balance equation to solve the steady-state probability.

[0097] S31. When a class of secondary users arrives at the system, a random preemptive access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived class of secondary users.

[0098] S311, when N CP,IDLE When >0, a newly arrived secondary user accesses an idle CP channel.

[0099] S312, when i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP When >0, the newly arrived type-1 secondary user accesses a CP channel occupied by a type-2 secondary user.

[0100] S313, when iCP +j CP =γ CP And i RP +j RP <γ RP When a new type of secondary user arrives with probability N RP,IDLE / γ RP -i RP -j RP Access an idle RP channel, or with probability k RP / γ RP -i RP -j RP Access an RP channel occupied by a second-class secondary user.

[0101] S314, when i CP +j CP =γ CP And i RP +j RP =γ RP When , a newly arrived class of secondary users will be blocked.

[0102] Specifically, Figure 3 As shown, when a new class-I secondary user SU1 arrives at the system, the CP spectrum pool is accessed first. If there is an idle CP channel, an idle CP channel is allocated to the newly arrived class-I secondary user. Otherwise, a CP channel currently occupied by a class-II secondary user is allocated to the newly arrived class-I secondary user. If all CP channels are occupied by primary users or class-I secondary users, the newly arrived class-I secondary user accesses the RP spectrum pool to determine whether there is a channel in the RP spectrum pool that is not occupied by the primary user and the class-I secondary user. If so, a channel that is not occupied by the primary user and the class-I secondary user is randomly and equally likely allocated to the newly arrived class-I secondary user. Otherwise, the newly arrived class-I secondary user will be blocked.

[0103] S32: When the second-class secondary user arrives at the system, a conflict avoidance cooperative access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived second-class secondary user.

[0104] S321, when i CP +j CP +k CP <γ CP When , the newly arrived second-class secondary user accesses an idle CP channel.

[0105] S322, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP<γ RP When , the newly arrived second-class secondary user accesses an idle RP channel.

[0106] S323, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP =γ RP When , the newly arrived second-class secondary users will be blocked. The steady-state probability π(s) can be obtained from the equilibrium equation ΠQ=0,Πe=1, where Q represents the transfer rate matrix; e represents the identity matrix and e=[1,1,...,1] T .

[0107] Specifically, Figure 4 As shown, when a new second-class secondary user SU2 arrives at the system, the CP spectrum pool is accessed first. If there is an idle CP channel, an idle CP channel is allocated to the newly arrived second-class secondary user; otherwise, the RP spectrum pool is accessed to determine whether there is an idle channel in the RP spectrum pool. If so, an idle RP channel is allocated to the newly arrived second-class secondary user, otherwise the newly arrived second-class secondary user will be blocked. The steady-state probability π(s) can be calculated from the equilibrium equation ΠQ=0, Πe=1.

[0108] S4. Calculate the blocking rate and call drop rate of the first-class secondary users and the second-class secondary users.

[0109] S41, solve the blocking rates β1 and β2 of the first-class secondary users and the second-class secondary users. For the newly arrived first-class secondary users, they will be blocked when all the channels in the system are occupied by the primary users and the first-class secondary users; for the newly arrived second-class secondary users, they will be blocked when there are no idle channels in the system. β1 and β2 are respectively:

[0110]

[0111]

[0112] Among them, π(s) represents the steady-state probability in state s.

[0113] S42, solve the call drop rates α1, α2 of the first and second secondary users. For the first secondary user, a new primary user arrives. When the RP channel is not fully occupied by the primary user and j RP >0, or i RP =γ RP , there is no idle CP channel and j CP> 0, the transmission of the first type of secondary users is interrupted by the primary users and they leave the system; for the second type of secondary users, when there is no idle CP channel and k CP >0, or i CP +j CP =γ CP And k RP When >0, the transmission of the second-class secondary user is interrupted by the first-class secondary user and leaves the system. α1 and α2 are:

[0114]

[0115]

[0116] S5. Calculate the throughput θ1, θ2, θ3 of the primary user, the first type of secondary user and the second type of secondary user:

[0117]

[0118] θ2=λ 21 (1-β1-α1) (8).

[0119] θ3=λ 22 (1-β2-α2) (9).

[0120] S6. Compromise the performance indicators of various systems and construct the system benefit function R:

[0121] R=r1θ1+r2θ2+r3θ3-r4(1 / μ 21 )(1-β1)-r5(1 / μ 22 )(1-β2)-r6(γ CP +γ RP ) (10)

[0122] Among them, r1 represents the benefit that can be obtained by successfully transmitting a primary user system; r2 represents the benefit that can be obtained by successfully transmitting a class-one secondary user system; r3 represents the benefit that can be obtained by successfully transmitting a class-two secondary user system; r4 and r5 represent the system loss of a class-one secondary user and a class-two secondary user staying in the system for one time slot respectively; r6 represents the loss of a channel provided to the system administrator.

[0123] S7. Use MATLAB to solve and obtain the maximum CP channel number γ of the system benefit function R CP * and the number of RP channels γ RP *.

[0124] The method also includes solving the optimal secondary user arrival rate that maximizes the system benefit function when there are only primary users and secondary users under non-ideal perception, specifically including the following steps:

[0125] S81. Assume that missed detection of primary users, missed detection of secondary users and false alarms occur with a certain probability on each channel, which are called missed detection rates p mp , missed detection rate p ms And the false alarm rate p f , set the energy detection threshold τ pu and τ su , and τ pu >τ su , missed detection rate p mp , missed detection rate p ms and false alarm rate p f The solution is as follows:

[0126]

[0127] in, N represents the number of times the secondary user detects the channel; γ represents the signal-to-noise ratio; represents the noise variance.

[0128] S82. When the secondary user senses that there are no idle CP channels and RP channels, solve the secondary user blocking rate P in state s. block :

[0129]

[0130] S83, solving the call drop rate P of the next type of secondary users in state s drop , secondary user call drop rate P drop It is the proportion of discarded secondary users among all arriving secondary users.

[0131] S831. When a secondary user accesses a channel occupied by a primary user or a secondary user, a conflict occurs between the secondary user and the primary user or between the secondary user and the secondary user. At this time, the conflicting secondary user drops the call. The secondary user drop rate under the secondary user access is:

[0132]

[0133] in, They represent the probability that a secondary user mistakenly accesses the CP and RP channels occupied by secondary users and primary users respectively; p0 represents the probability that a secondary user detects that there are no idle channels in the CP channel pool.

[0134] S832. When the primary user seizes the channel occupied by the secondary user, the secondary user correctly senses the arrival of the primary user and withdraws from the current channel. At this time, the secondary user's call drop occurs. The secondary user's call drop rate under the primary user access is:

[0135]

[0136] S833, state s next lower user call drop rate P drop for:

[0137] P drop =p drop_s1 +p drop_s2 (15).

[0138] S84. Solving the secondary user effective throughput η s , secondary user effective throughput η s is the number of secondary users that successfully transmit per unit time, and the secondary user call drop rate and secondary user blocking rate under state s are solved:

[0139] η s =λ s (1-P block -P drop ) (16)

[0140] Among them, λ s Represents the secondary user arrival rate.

[0141] S85. According to the secondary user effective throughput η s Determine the personal benefit function U ind :

[0142]

[0143] S86. According to the personal benefit function U ind Determine the system benefit function U sys :

[0144] U soc =(1-P block -P drop ) s U ind (18).

[0145] S87. Obtaining system benefit function U sys The optimal secondary user arrival rate when

[0146] Specifically, Figure 5As shown, the access of the newly arrived primary user is scheduled by the control center. When the control center receives the access request of the primary user, it first determines whether there is an RP channel in the RP channel pool that is not occupied by the primary user through the local database. If so, it is randomly assigned to the primary user, and the primary user starts data transmission. If not, it determines whether there is an idle channel in the CP channel pool. If there is an idle channel, it is assigned to the primary user, and the primary user starts data transmission. If not, the CP channel occupied by the secondary user is assigned to the primary user, and the occupancy information of the primary user is stored in the local database. If both the RP channel pool and the CP channel pool are occupied by the primary user, the newly arrived primary user leaves the system due to congestion. If the primary user misses the detection when preempting the secondary user, the transmission fails. It is assumed that when the secondary user correctly perceives the arrival of the primary user, it can immediately withdraw from the current channel.

[0147] like Figure 6 As shown, the newly arrived secondary user first performs spectrum sensing on all channels in the CP channel pool, and selects an idle CP channel at random according to the sensing result and accesses it. If no idle channel is sensed in the CP channel pool, all channels in the RP channel pool are sensed, and an idle RP channel is selected at random according to the sensing result and accessed. If it is sensed that there is no idle channel in both the CP channel pool and the RP channel pool, the newly arrived secondary user leaves the system due to congestion. Due to the influence of signal attenuation and other factors in the actual network operation environment, false alarms and missed detections will inevitably occur in the secondary user's perception of the channel. When a false alarm occurs, the secondary user may miss the opportunity to access an idle channel; when a missed detection occurs, there is a situation where secondary users collide with secondary users or secondary users collide with primary users, and both the primary user and secondary users that collide are discarded.

[0148] In a specific embodiment, the system parameters used in setting the secondary user classification simulation experiment are shown in Table 1, and the system parameters used in setting the primary user and the secondary user and the non-ideal perception simulation experiment are shown in Table 2.

[0149]

[0150]

[0151] Table 1

[0152]

[0153] Table 2

[0154] The simulation of the blocking rate and call drop rate of the second type of secondary users under the secondary user classification is as follows Figure 7 and Figure 8 As shown in Figure 2, the simulation of the blocking rate and call drop rate of secondary users under non-ideal perception with only primary users and secondary users is shown in Figure 2. Fig. 9 and Fig.10As shown in the figure, it can be seen that as the simulation time goes by, these performance indicators gradually converge to the corresponding theoretical values ​​after the initial fluctuations, which shows that the derivation of the system performance indicator formula is correct and the proposed model is correct and reasonable.

[0155] The present invention designs a dynamic spectrum allocation method based on dual spectrum pools. Aiming at the problems that the increasing demand for data transmission, the shortage of existing spectrum resources, and the diversity of secondary user transmission requirements can no longer be met, the secondary user classification strategy is introduced into the existing dynamic spectrum allocation strategy; the secondary users are divided into two categories, and a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy is constructed; the steady-state probability of the equilibrium equation solution model is established to obtain the blocking rate, call drop rate and performance indicators of the throughput of the first and second categories of secondary users and the third category of users under steady state; considering the non-ideality of secondary users' perception of spectrum, the dual energy detection threshold is introduced into the dynamic spectrum allocation strategy; in order to take into account the service quality of the main users and the collision conflict problem caused by non-ideal perception, a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy is constructed; the equilibrium equation is used to perform steady-state analysis of the queuing model, and the blocking rate, call drop rate and effective throughput of the secondary users are used as indicators to evaluate the system performance.

[0156] Finally, it should be noted that the above embodiments are only intended to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A dynamic spectrum allocation method based on dual spectrum pools, characterized in that: It includes the following steps: S1. Determine relevant parameters for dynamic spectrum allocation, wherein the relevant parameters include the arrival rate λ1 of the main user in the secondary user classification strategy, the arrival rate λ 21 , the arrival rate of the second-class secondary users λ 22 , the service rate of the main user μ1, the service rate of a type of secondary user μ 21 , the service rate of the second-class secondary users μ 22 , the number of CP and RP channels occupied by the main user i CP ,i RP , the number of CP and RP channels occupied by a type of secondary user j CP ,j RP , the number of CP and RP channels occupied by the second type of secondary users k CP ,k RP And the number of idle channels N of CP and RP CP,IDLE ,N RP,IDLE , the N CP,IDLE ,N RP,IDLE Respectively expressed as: N CP,IDLE =c CP -i CP -j CP -k CP (1) N RP,IDLE =c RP -i RP -j RP -k RP (2) Among them, γ CP Indicates the number of CP channels; γ RP Indicates the number of RP channels; S2. When a primary user arrives at the system, the allocation of the newly arrived primary user is determined based on relevant parameters; S3. Construct a dynamic spectrum allocation strategy model combining a random preemptive access strategy and a conflict avoidance cooperative access strategy, determine the allocation of newly arrived first-class secondary users and second-class secondary users, and establish a balance equation to solve the steady-state probability; S4, solving the blocking rate and call drop rate of the first-class secondary users and the second-class secondary users; S5. Calculate the throughput θ1, θ2, θ3 of the primary user, the first type of secondary user and the second type of secondary user: θ2=λ 21 (1-β1-α1) (8) θ3=λ 22 (1-β2-α2) (9) Where β1, β2 represent the blocking rates of the first and second secondary users respectively; α1, α2 represent the call drop rates of the first and second secondary users respectively; π(s) represents the steady-state probability under state s; S6. Compromise the performance indicators of various systems and construct the system benefit function R: R=r1θ1+r2θ2+r3θ3-r4(1 / μ 21 )(1-β1)-r5(1 / μ 22 )(1-β2)-r6(γ CP +g RP ) (10) Among them, r1 represents the benefit that can be obtained by successfully transmitting a primary user system; r2 represents the benefit that can be obtained by successfully transmitting a first-class secondary user system; r3 represents the benefit that can be obtained by successfully transmitting a second-class secondary user system; r4 and r5 represent the system loss of a first-class secondary user and a second-class secondary user staying in the system for one time slot respectively; r6 represents the loss of one channel provided by the system administrator; S7. Use MATLAB to solve and obtain the maximum CP channel number γ of the system benefit function R CP * and the number of RP channels γ RP *; The step S2 specifically includes the following steps: S21, when i RP +j RP +k RP ≤γ RP That is N RP,IDLE ≥0, the newly arrived primary user arrives with probability N RP,IDLE / (γ RP -i RP ) randomly accesses an idle RP channel, or with probability j RP / (γ RP -i RP ) accesses an RP channel occupied by a class of secondary users, or with probability k RP / (γ RP -i RP ) accesses an RP channel occupied by a second-class secondary user; S22, when i RP =γ RP And N CP,IDLE When >0, the newly arrived primary user accesses an idle CP channel; S23, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP > 0, the newly arrived primary user accesses a CP channel occupied by a second-class secondary user; S24, when i RP =γ RP 、i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and j CP When >0, the newly arrived primary user accesses a CP channel occupied by a type of secondary user; S25, when i RP =γ RP And i CP =γ CP When , the newly arrived primary user will be blocked; The step S3 specifically comprises the following steps: S31, when a class of secondary users arrives at the system, a random preemptive access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived class of secondary users; S311, when N CP,IDLE When >0, a newly arrived secondary user accesses an idle CP channel; S312, when i CP +j CP +k CP =γ CP That is N CP,IDLE = 0 and k CP When >0, the newly arrived secondary user of type 1 accesses a CP channel occupied by the secondary user of type 2; S313, when i CP +j CP =γ CP And i RP +j RP <γ RP When a new type of secondary user arrives with probability N RP,IDLE / (γ RP -i RP -j RP ) accesses an idle RP channel, or with probability k RP / (γ RP -i RP -j RP ) accesses an RP channel occupied by a second-class secondary user; S314, when i CP +j CP =γ CP And i RP +j RP =γ RP When , a newly arrived class of secondary users will be blocked; S32, when the second-class secondary user arrives at the system, a conflict avoidance cooperative access strategy allocation model is constructed based on relevant parameters to determine the allocation of the newly arrived second-class secondary user; S321, when i CP +j CP +k CP <γ CP When , the newly arrived second-class secondary user accesses an idle CP channel; S322, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP <γ RP When , the newly arrived second-class secondary user accesses an idle RP channel; S323, when i CP +j CP +k CP =γ CP And i RP +j RP +k RP =γ RP When the newly arrived second-class secondary user is blocked, the steady-state probability π(s) is obtained by the equilibrium equation ΠQ=0,Πe=1, where Q represents the transfer rate matrix; e represents the identity matrix and e=[1,1,...,1] T .

2. The method for dynamic spectrum allocation based on dual spectrum pools according to claim 1, characterized in that: The step S4 specifically comprises the following steps: S41, solve the blocking rates β1 and β2 of the first-class secondary users and the second-class secondary users. For the newly arrived first-class secondary users, they will be blocked when all the channels in the system are occupied by the primary users and the first-class secondary users; for the newly arrived second-class secondary users, they will be blocked when there are no idle channels in the system. β1 and β2 are respectively: S42, solve the call drop rates α1, α2 of the first and second secondary users. For the first secondary user, a new primary user arrives. When the RP channel is not fully occupied by the primary user and j RP >0, or i RP =γ RP , there is no idle CP channel and j CP > 0, the transmission of the first type of secondary users is interrupted by the primary users and they leave the system; for the second type of secondary users, when there is no idle CP channel and k CP >0, or i CP +j CP =γ CP And k RP When >0, the transmission of the second-class secondary user is interrupted by the first-class secondary user and leaves the system. α1 and α2 are:

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