Industrial Internet of Things Service Quality Assurance and Spectrum Sharing Method Based on Sensing and Communication Integration

Abstract

The present invention discloses a method for service quality guarantee and spectrum sharing based on integrated communication and sensing in the industrial Internet of Things, including: in the underlying cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of constant transmission power; in the underlying cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of adaptive transmission power; in the upper-layer cognitive radio network, when the primary user and the secondary user transmit separately in the time domain, a strategy of fixed time slot allocation is adopted; in the upper-layer cognitive radio network, when the primary user and the secondary user transmit separately in the time domain, a strategy of adaptive time slot allocation is adopted. The method of the present invention can maximize the throughput of the secondary user in both the underlying cognitive radio network and the upper-layer cognitive radio network, and simultaneously meet the service quality requirements of the primary user.

Description

Technical Field

[0001] The present invention belongs to the research field of integrated communication and sensing in industrial Internet of Things, and relates to a method for quality of service guarantee and spectrum sharing based on integrated communication and sensing in industrial Internet of Things. Background Art

[0002] In the past decade, cognitive radio has been proven to be an efficient and promising technology for solving the problems of spectrum shortage and insufficient spectrum utilization. It can effectively fill the spectrum holes caused by static spectrum allocation. In traditional cognitive radio networks, secondary users are allowed to use the authorized spectrum of primary users. However, to protect the privileges of primary users, it is required that primary users cannot sense the presence of secondary users, which limits secondary users and results in ineffective spectrum utilization. Spectrum sensing is performed by secondary users to discover spectrum holes, but the spectrum sensing is not accurate enough to avoid interference from secondary users to primary users, which degrades the channel quality of primary users.

[0003] To further improve the effectiveness of spectrum utilization, a class of research relaxes the restrictions on secondary users and enables primary users to participate in sensing transmissions in the radio network. On the one hand, primary users share channel information with secondary users so that secondary users can use the corresponding spectrum according to this information. On the other hand, primary users and secondary users jointly determine a cooperative transmission scheme to optimize the performance of secondary users while ensuring the benefits of primary users. Although these research works provide new ways for spectrum use, several key issues regarding the cooperation between primary users and secondary users have not been thoroughly studied. First, the impact of secondary users on primary users is usually described by interference power, which cannot directly and accurately reflect the quality of service status of primary users. Second, the quality of service requirements of primary users may vary significantly due to different service types. Therefore, a unified framework should be constructed based on the quality of service requirements of primary users to formulate the strategies of secondary users. Finally, under the quality of service constraints of primary users, how much resources should primary users and secondary users share, and how secondary users can help primary users relay more resources.

[0004] To solve the above problems, it is a very feasible direction to propose a spectrum access method for secondary users that can protect the quality of service of primary users in a cooperative cognitive radio network. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art, and provides a method for quality of service guarantee and spectrum sharing based on integrated communication and sensing in industrial Internet of Things. This method can maximize the throughput of secondary users in both the underlying cognitive radio network and the top-level cognitive radio network, and at the same time meet the quality of service requirements of primary users.

[0006] To achieve the above purpose, the method for quality of service guarantee and spectrum sharing based on integrated communication and sensing in industrial Internet of Things described in the present invention includes:

[0007] In the underlying cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of constant transmission power;

[0008] In the underlying cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of adaptive transmission power;

[0009] In the upper-layer cognitive radio network, when the primary user and the secondary user transmit separately in the time domain, a strategy of fixed time slot allocation is adopted;

[0010] In the upper-layer cognitive radio network, when the primary user and the secondary user transmit separately in the time domain, a strategy of adaptive time slot allocation is adopted.

[0011] It also includes:

[0012] The quality of service requirement of the primary user is described by the effective capacity metric C(θ), where θ represents the quality of service index. When θ is larger, it indicates that the delay quality of service requirement is more stringent.

[0013] During the simultaneous transmission of the primary user and the secondary user in the underlying cognitive radio network:

[0014] The primary user link and the secondary user link work simultaneously;

[0015] The transmission power of the primary user remains unchanged, and the transmission power of the secondary user is constant or dynamically adjusted;

[0016] The primary user and the secondary user adjust the transmission rate in each time frame according to the instantaneous interference between them;

[0017] The receivers of the primary user and the secondary user decode independently.

[0018] When the primary user and the secondary user transmit simultaneously in the underlying cognitive radio network, the specific process of the secondary user adopting the strategy of constant transmission power is as follows:

[0019] Taking maximizing the average throughput of the secondary user, meeting the effective capacity requirement of the primary user, and limiting the average transmission power of the secondary user as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal transmission power of the secondary user.

[0020] When the primary user and the secondary user transmit simultaneously in the underlying cognitive radio network, the specific process of the secondary user adopting the strategy of adaptive transmission power is as follows:

[0021] Taking the maximization of the average throughput of secondary users, meeting the effective capacity requirements of primary users, limiting the average transmission power of secondary users, and limiting the instantaneous upper bound of the transmission power of secondary users as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal transmission power scheme for secondary users. Among them, based on optimization theory and probability transmission strategies, the optimization problem is transformed into a convex optimization problem, and then the Lagrangian equation of the optimization problem is solved based on the KKT conditions, and the Lagrange multipliers are obtained through numerical search methods to obtain the optimal transmission power scheme for secondary users.

[0022] In the time-domain separated transmission process of primary users and secondary users in the top-layer cognitive radio network:

[0023] Both the primary user transmitter and the secondary user transmitter transmit data with constant power;

[0024] The primary user transmitter and the secondary user transmitter transmit data in a time-domain separated manner;

[0025] The entire time slot is equally divided into two phases, and each phase is divided into two time slots, which are respectively marked as time slot 1, time slot 2, time slot 3, and time slot 4. Among them, the time lengths of time slot 1 and time slot 3 are equal, and the time lengths of time slot 2 and time slot 4 are equal;

[0026] Fix or dynamically adjust the time ratio of time slot 1.

[0027] In the top-layer cognitive radio network, the specific process of the primary user and the secondary user adopting a fixed time slot allocation strategy during time-domain separated transmission is as follows: Taking the maximization of the average throughput of secondary users, meeting the effective capacity requirements of primary users, keeping the average transmission powers of primary users and secondary users constant, and keeping the time ratio of time slot 1 under any channel state information unchanged as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal time ratio of time slot 1.

[0028] The specific process of the primary user and the secondary user adopting an adaptive time slot allocation strategy during time-domain separated transmission in the top-layer cognitive radio network is as follows:

[0029] Taking the maximization of the average throughput of secondary users, meeting the effective capacity requirements of primary users, and keeping the average transmission powers of primary users and secondary users constant as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal adaptive time slot allocation scheme;

[0030] Among them, the Lagrangian equation of the optimization problem is solved based on the KKT conditions, and the Lagrange multipliers are obtained through numerical search methods to obtain the optimal adaptive time slot allocation scheme.

[0031] The present invention has the following beneficial effects:

[0032] When the method for ensuring service quality and spectrum sharing based on integrated communication and sensing of the industrial Internet of Things described in the present invention is specifically operated, the primary user and the secondary user jointly design a transmission strategy in a collaborative manner by sharing channel and service quality information, adjusting the transmission rate, and adjusting the resource allocation strategy, so as to maximize the throughput of the secondary user while meeting the service quality requirements of the primary user. Compared with the traditional cognitive radio network, the present invention makes more full use of the spectrum, can directly reflect the service quality status of the primary user, can obtain how the secondary user controls its transmission power, and can obtain how much resources are shared by the primary user and the secondary user. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a system model diagram of a cooperative cognitive radio network;

[0034] Figure 2 It is a schematic diagram of the cooperation protocol in the top-layer cognitive radio network of the present invention;

[0035] Figure 3 It is a relationship curve graph of the average throughput of the secondary user and the service quality index θ of the primary user in the present invention;

[0036] Figure 4 It is a relationship curve graph of the average power consumption of the secondary user and the service quality index θ of the primary user in the present invention;

[0037] Figure 5 It is a schematic diagram of how many time slot resources the secondary user will use when collaborating in the present invention;

[0038] Figure 6 It is a relationship curve graph of the average throughput of the secondary user and the transmission power budget of the primary user in the present invention;

[0039] Figure 7 It is a relationship curve graph of the average throughput of the secondary user and the transmission power budget of the secondary user in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In the method for ensuring service quality and spectrum sharing based on integrated communication and sensing of the industrial Internet of Things described in the present invention, the primary user and the secondary user jointly design a transmission strategy in a collaborative manner by sharing channel and service quality information, adjusting the transmission rate, and adjusting the resource allocation strategy. The present invention includes two types of cognitive radio networks: in the bottom-layer cognitive radio network, there is cross-interference between the transceivers of the primary user and the secondary user, and the secondary user needs to control its transmission power and does not violate the service quality constraints of the primary user; in the top-layer cognitive radio network, the primary user and the secondary user avoid cross-interference through time-domain separation transmission, the primary user releases some time slots to the secondary user, and the secondary user transmits data to the primary user in an amplify-and-forward manner.

[0041] REFERENCEFigure 1 and Figure 2 The method for guaranteeing service quality and spectrum sharing based on communication and sensing integration in the industrial Internet of Things according to the present invention includes the following contents:

[0042] 1) Construct a model for simultaneous transmission of primary users and secondary users in the underlying cognitive radio network:

[0043] The specific process of step 1) is as follows:

[0044] 1a) The primary user link and the secondary user link work simultaneously;

[0045] 1b) The transmission power of the primary user transmitter remains unchanged, and the transmission power of the secondary user transmitter is dynamically adjusted;

[0046] 1c) The physical signal transmission model is:

[0047]

[0048] 1d) The primary user and the secondary user adjust the transmission rate in each time frame according to the instantaneous interference between them. The transmission rates (nats / frame) of the primary user link and the secondary user link are:

[0049]

[0050] Wherein, P1 and P2 are the transmission powers of the primary user transmitter and the secondary user transmitter respectively; P2 changes with the channel state information h; x p and x s are the complex signals transmitted by the primary user link and the secondary user link respectively; y pr and y sr are the received signals of the primary user receiver and the secondary user receiver respectively; n pr and n sr are independent circularly symmetric complex Gaussian noises with a variance of σ 2 ; h 11 、h 12 、h 22 、h 21 and h ps are the power gains of the channels between the primary user transmitter - primary user receiver, primary user transmitter - secondary user receiver, secondary user transmitter - secondary user receiver, secondary user transmitter - primary user receiver, and primary user transmitter - secondary user transmitter respectively;

[0051] 1e) There is no complex scheduling and coordination process between the primary user and the secondary user transmitters. Therefore, the primary user and secondary user receivers decode independently and have a simple decoder and protocol structure;

[0052] 2) When the primary user and the secondary user transmit simultaneously in the underlay cognitive radio network, the secondary user adopts a strategy of constant transmission power;

[0053] The specific process of step 2) is as follows:

[0054] 2a) By solving the optimization problem A1, the optimal transmission power of the secondary user is obtained

[0055]

[0056]

[0057]

[0058] Among them, is the average transmission power budget of the secondary user; is the effective capacity of the primary user.

[0059] 2b) According to the above constraints, let be the solution of the following equation:

[0060]

[0061] 2c) The optimal solution of A1 is:

[0062]

[0063] 3) When the primary user and the secondary user transmit simultaneously in the underlay cognitive radio network, the secondary user adopts a strategy of adaptive transmission power;

[0064] The specific process of step 3) is as follows:

[0065] 3a) Construct the optimization problem A2 to obtain the optimal transmission power scheme of the secondary user;

[0066]

[0067]

[0068]

[0069]

[0070] Among them, P upper is the upper bound of the instantaneous power;

[0071] 3b) A2 is not a convex optimization problem, and it is corrected to obtain the convex optimization problem A2_a.

[0072] Constraint 1) in A2 can be written as:

[0073]

[0074] Among them, g(P2) is monotonically decreasing and has an inflection point (P, g(P)).

[0075] U is the convex hull formed by (P2, g(P2)), is the upper boundary function and is a concave function. Based on the optimization theory and probability transmission strategy, the non-concave region of g(P2) is replaced by a straight line segment to convert the non-concave function g(P2) into a concave function to make the optimization problem easy to handle.

[0076] According to the function g(P2), P2 ∈ [0, P up , three cases are obtained

[0077] ① Case 1: g(P2) is below the straight line segment connecting (0, g(0)) and (P up , g(P up )) The straight line segment forms the upper boundary as:

[0078]

[0079] The maximum achievable transmission rate of the secondary user is:

[0080]

[0081] ② Case 2: (P, g(P)) is the only inflection point within [0, P up , and it is possible to uniquely find such that the straight line connecting and (P up , g(P up )) is the tangent of g(P2) at The straight line segment and the g(P2) within form the upper boundary:

[0082]

[0083] The maximum achievable transmission rate of the secondary user is:

[0084]

[0085] ③ Case 3: (P, g(P)) is the only inflection point within [0, P up . If P up < P, then g(P2) is a concave function within [0, P up , and g(P2) itself forms the upper boundary:

[0086]

[0087] The maximum achievable transmission rate of the secondary user is:

[0088]

[0089] 3c) Replace g(P2) with Construct the modified convex optimization problem A2_a:

[0090]

[0091]

[0092]

[0093]

[0094] The Lagrangian equation of A2_a is:

[0095] L1 = E{J1}

[0096] Where λ and η are the Lagrange multipliers of constraints 1) and 2).

[0097] A2_a is a convex optimization function, and the optimal solution satisfies:

[0098]

[0099] For case one, and are constant, and are represented by and respectively, then there is:

[0100]

[0101] For case two and case three, a closed-form expression does not exist and can be obtained by numerical search.

[0102] 3d) After obtaining , based on the KKT conditions, select the Lagrange multipliers and to satisfy:

[0103]

[0104] and are obtained by numerical search, and the Lagrangian dual problem is optimized by gradient descent to obtain and

[0105] 4) Model of time-domain separated transmission between primary users and secondary users in the top-layer cognitive radio network:

[0106] The specific process of step 4) is as follows:

[0107] 4a) Both the primary user transmitter and the secondary user transmitter transmit data with a constant power.

[0108] 4b) The entire time slot is equally divided into two phases, and each phase is further divided into two time slots, which are respectively labeled as time slots 1 to 4, where the lengths of time slots 1 and 3 are equal, and the lengths of time slots 2 and 4 are equal.

[0109] 4c) Top-layer data transmission method: The primary user transmitter transmits its own data in the first phase, transmits at a higher rate in time slot 1, and transmits at a lower rate in time slot 2; in time slot 1, the secondary user transmitter can receive and store the information transmitted by the primary user transmitter; in time slot 3, the secondary user transmitter amplifies the power and relays and forwards the signal to the primary user receiver. Therefore, the primary user receiver receives two copies of the signal, each experiencing different channel fades. Correspondingly, the primary user receiver processes the two copies of the signal through maximum ratio combining. Finally, in time slot 4, the secondary user transmitter transmits its own data.

[0110] 4d) The physical layer transmission signal is:

[0111]

[0112]

[0113]

[0114]

[0115]

[0116] where y pr,i , y ss,i and y sr,i are the received signals of the primary user receiver, the secondary user transmitter, and the secondary user receiver in the i-th time slot respectively; x p,i is the transmission signal of the primary user in the i-th time slot; n pr,i , n ss,i and n sr,i are all independent circularly symmetric complex Gaussian noises.

[0117] 5) When the primary users and secondary users in the top-layer cognitive radio network perform time-domain separated transmission, a fixed time slot allocation strategy is adopted.

[0118] The specific process of step 5) is as follows:

[0119] 5a) The construction optimization problem B1 obtains the optimal time ratio of time slot 1

[0120]

[0121]

[0122] Fixed

[0123] where R1(α) and R2(α) are the achievable rates of the primary user and the secondary user in one frame respectively.

[0124] 5b) If

[0125]

[0126] it indicates that even without cooperation, the quality-of-service requirements of the primary user can be satisfied, and the optimal solution maximizes the signal transmission time slot length of the secondary user.

[0127] If

[0128]

[0129] then the optimal solution indicates that even if all cooperative transmissions are carried out in the second phase, the quality-of-service requirements of the primary user still cannot be satisfied.

[0130] Except for the above two cases, the unique optimal solution is obtained from the following equation

[0131]

[0132] 6) When the primary user and the secondary user in the top-level cognitive radio network perform time-domain separation transmission, an adaptive time slot allocation strategy is adopted;

[0133] The specific process of step 6) is as follows:

[0134] 6a) Formulate the optimization problem B2 to obtain the optimal time slot allocation scheme:

[0135]

[0136]

[0137]

[0138] where α(h) is the time ratio of time slot 1.

[0139] 6b) The Lagrangian equation of B2 is:

[0140] L2 = E{J2}

[0141] Among them, μ is the Lagrange multiplier related to the constraint condition.

[0142] Under the boundary condition α ∈ [0, 1], solve the following equation

[0143]

[0144] to obtain the optimal α * as:

[0145]

[0146] Among them, [·] + = max{0, ·}.

[0147] 6c) Select a μ to make the constraint 1) in B2 hold with equality. Through the Lagrangian dual problem of the optimization problem B2, the Lagrange multiplier can be obtained by using the gradient descent method.

[0148] Simulation experiment

[0149] From Figure 3 it can be seen that in the underlying cognitive radio network, the adaptive power transmission strategy is superior to the constant power transmission strategy; the stricter the quality of service requirement of the primary user, the smaller the achievable throughput of the secondary user when using the constant power transmission strategy; the adaptive power allocation scheme is less sensitive to the change of the quality of service of the primary user; when the quality of service requirement of the primary user is very strict, both the constant power transmission and the adaptive power transmission have zero throughput; when the quality of service is very high or very low, the difference between the two time slot allocation schemes disappears; the time slot allocation algorithm of the top layer model is superior to the power allocation strategy of the bottom layer model.

[0150] From Figure 4 it can be seen that the stricter the quality of service constraint of the primary user, the less the transmission power of the secondary user.

[0151] From Figure 5 it can be seen that when the quality of service requirement is relatively loose, non - cooperation can also meet the quality of service requirement of the primary user; when the quality of service requirement is very strict, the secondary user needs to use all resources to relay the primary user's resources, making the average α equal to 1.

[0152] From Figure 6 it can be seen that when the transmission power of the primary user increases, the interference to the secondary user increases, and at the same time the achievable throughput of the secondary user increases, achieving better performance.

[0153] From Figure 7 it can be seen that when the transmission power of the secondary user increases, the achievable throughput of the secondary user will increase, achieving better performance.

Claims

1. An industrial Internet of Things service quality guarantee and spectrum sharing method based on integrated communication and sensing, characterized in that, including: In an underlay cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of constant transmission power; In an underlay cognitive radio network, when the primary user and the secondary user transmit simultaneously, the secondary user adopts a strategy of adaptive transmission power; In an overlay cognitive radio network, when the primary user and the secondary user transmit in a time-domain separated manner, a fixed time slot allocation strategy is adopted; In an overlay cognitive radio network, when the primary user and the secondary user transmit in a time-domain separated manner, an adaptive time slot allocation strategy is adopted; In an underlay cognitive radio network, when the primary user and the secondary user transmit simultaneously, the specific process of the secondary user adopting the strategy of adaptive transmission power is as follows: Taking maximizing the average throughput of the secondary user, meeting the effective capacity requirement of the primary user, restricting the average transmission power of the secondary user, and restricting the instantaneous upper bound of the transmission power of the secondary user as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal transmission power scheme of the secondary user. Among them, based on the optimization theory and the probability transmission strategy, the optimization problem is transformed into a convex optimization problem, and then the Lagrangian equation of the optimization problem is solved based on the KKT conditions, and the Lagrange multipliers are obtained through a numerical search method to obtain the optimal transmission power scheme of the secondary user; In an overlay cognitive radio network, the specific process of the primary user and the secondary user adopting a fixed time slot allocation strategy when transmitting in a time-domain separated manner is as follows: Taking maximizing the average throughput of the secondary user, meeting the effective capacity requirement of the primary user, keeping the average transmission power of the primary user and the secondary user constant, and keeping the time ratio of time slot 1 under any channel state information unchanged as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal time ratio of time slot 1; In an overlay cognitive radio network, the specific process of the primary user and the secondary user adopting an adaptive time slot allocation strategy when transmitting in a time-domain separated manner is as follows: Taking maximizing the average throughput of the secondary user, meeting the effective capacity requirement of the primary user, and keeping the average transmission power of the primary user and the secondary user constant as the objectives, an optimization problem is constructed, and then the optimization problem is solved to obtain the optimal adaptive time slot allocation scheme; Among them, the Lagrangian equation of the optimization problem is solved based on the KKT conditions, and the Lagrange multipliers are obtained through a numerical search method to obtain the optimal adaptive time slot allocation scheme.

2. The method for service quality guarantee and spectrum sharing based on integrated communication and sensing in the industrial Internet of Things according to claim 1, wherein, also including: The quality of service requirement of the primary user is described by the effective capacity metric C(θ), where θ represents the quality of service index. Among them, the larger θ is, the more stringent the delay quality of service requirement is.

3. The method for service quality guarantee and spectrum sharing based on integrated communication and sensing in the industrial Internet of Things according to claim 1, wherein During the simultaneous transmission of the primary user and the secondary user in an underlay cognitive radio network: The primary user link and the secondary user link work simultaneously; The transmission power of the primary user remains unchanged, and the transmission power of the secondary user is constant or dynamically adjusted; The primary user and the secondary user adjust the transmission rate in each time frame according to the instantaneous interference between them; The receivers of the primary user and the secondary user decode independently.

4. The method for ensuring service quality and spectrum sharing based on integrated communication and sensing in the industrial Internet of Things according to claim 1, wherein In an underlay cognitive radio network, when the primary user and the secondary user transmit simultaneously, the specific process of the secondary user adopting the strategy of constant transmission power is as follows: Construct an optimization problem with the goal of maximizing the average throughput of secondary users, meeting the effective capacity requirements of primary users, and limiting the average transmit power of secondary users, and then solve the optimization problem to obtain the optimal transmit power of secondary users.

5. The method for ensuring service quality and spectrum sharing based on integrated communication and sensing in the industrial Internet of Things according to claim 1, characterized in that, In the top-level cognitive radio network during the time-domain separated transmission of primary users and secondary users: Both the primary user transmitter and the secondary user transmitter transmit data with a constant power; The primary user transmitter and the secondary user transmitter transmit data in a time-domain separated manner; The entire time slot is equally divided into two phases, and each phase is divided into two time slots, which are respectively labeled as time slot 1, time slot 2, time slot 3, and time slot 4. Among them, the time lengths of time slot 1 and time slot 3 are equal, and the time lengths of time slot 2 and time slot 4 are equal; Fix or dynamically adjust the time ratio of time slot 1.

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