CN112821969B - Hybrid dynamic spectrum access method and device of full-duplex cognitive wireless network - Google Patents
Hybrid dynamic spectrum access method and device of full-duplex cognitive wireless network Download PDFInfo
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- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention provides a hybrid dynamic spectrum access method and a device of a full-duplex cognitive wireless network, wherein the method comprises the following steps: establishing a dual-channel radio frequency front end by combining full duplex cognition; establishing a bottom layer with limited energy and an interlaced mixed mode by using a time slot strategy; obtaining energy consumption and sampling in a sensing stage and a transmission stage; calculating the probability of false alarm and collision detection; establishing a full-duplex discrete four-state Markov transfer process; efficiently allocating limited energy to sensing and transmission to maximize traffic; an exhaustive search finds the best solution based on a limited number of perceptual samples. By the scheme, faster spectrum sensing and more reliable dynamic spectrum access can be realized, data transmission flow is improved, the reliability of conflict detection is guaranteed, and the information transmission rate of a secondary user is optimized under the condition of energy limitation.
Description
Technical Field
The invention relates to the field of cognitive wireless networks, in particular to a hybrid dynamic spectrum access method and a hybrid dynamic spectrum access device for a full-duplex cognitive wireless network.
Background
Cognitive wireless networks are dedicated to efficiently utilizing spectrum to solve spectrum scarcity problems, and are being developed for intelligent communication networks and adaptive radios by exploring cognitive functions. Currently, most communication systems are defined by hardware, have fixed resources, and operate in pre-allocated frequency bands. As a research hotspot, the cognitive radio network converts traditional radio into reconfigurable communication and has adaptive sensing and transmission functions.
The cognitive wireless network aims at efficiently utilizing spectrum resources, is a promising dynamic spectrum access technology and consists of a Secondary User (SU) and a Primary User (PU). The primary user obtains the authorized spectrum, and the secondary user can transmit data only by borrowing the primary user spectrum. The method comprises the following steps that a secondary user uses three main dynamic spectrum access technologies, namely a bottom layer (underlay), an overlay and an interlace, wherein in the bottom layer method, the secondary user and a main user are transmitted simultaneously, and meanwhile, the communication of the main user is not influenced; in the coverage method, a secondary user and a primary user transmit simultaneously, and the power of the secondary user is not only distributed to a secondary user network, but also serves as a relay of the primary user network; in the interleaving method, a secondary user and a primary user network coexist, and when the secondary user identifies a spectrum hole, data can be transmitted opportunistically.
Two functions of cognitive wireless networks are sensing and transmission. In a conventional network environment, spectrum sensing is performed in a time slot prior to data transmission, and is operated in a half-duplex mode. The cognitive radio network uses a listen-before-talk protocol in this mode, with a radio frequency channel for sensing and data transmission. Although the half-duplex mode of operation is widely used, two key issues remain: firstly, the sensing time slot shortens the data transmission time, so that the flow is correspondingly reduced; secondly, due to discontinuous perception, the reliability of detection is damaged, so that the cognitive radio network cannot detect the state change of the master user during the data transmission time slot, and the conflict is easily caused.
Disclosure of Invention
In view of this, embodiments of the present invention provide a hybrid dynamic spectrum access method and apparatus for a full-duplex cognitive wireless network, so as to solve the problems that the existing cognitive wireless network has low transmission flow and is easy to generate data collision.
In a first aspect of the embodiments of the present invention, a method for accessing a hybrid dynamic spectrum of a full-duplex cognitive wireless network is provided, including:
establishing a dual-channel radio frequency front end, a spectrum sensing module and a cognitive engine module, wherein the radio frequency front end comprises full duplex operation and control;
dividing time into a plurality of frames by using a time slot strategy, determining a spectrum access state according to a sensing result in each frame, and establishing a data transmission mode of a bottom layer with limited energy and interweaving;
acquiring energy consumption and perception sampling of a data perception stage and a data transmission stage;
respectively calculating the probability of false alarm and collision detection in different modes;
establishing a full-duplex discrete four-state Markov transfer model;
distributing limited energy to a sensing process and a transmission process to maximize flow;
and exhaustively obtaining an optimal solution according to the limited sensing samples to obtain a spectrum access result.
In a first aspect of the embodiments of the present invention, a hybrid dynamic spectrum access apparatus for a full-duplex cognitive wireless network is provided, including:
the system comprises a construction unit, a spectrum sensing module and a cognitive engine module, wherein the construction unit is used for constructing a dual-channel radio frequency front end, the spectrum sensing module and the cognitive engine module, and the radio frequency front end comprises full duplex operation and control;
the device comprises an establishing unit, a data transmission unit and a data transmission unit, wherein the establishing unit is used for dividing time into a plurality of frames by using a time slot strategy, determining a spectrum access state according to a sensing result in each frame, and establishing a data transmission mode of a bottom layer with limited energy and interweaving;
the acquisition unit is used for acquiring energy consumption and sensing samples of a data sensing stage and a data transmission stage;
the calculating unit is used for respectively calculating the probability of false alarm and collision detection in different modes;
the model building unit is used for building a full-duplex discrete four-state Markov transfer model;
the distribution unit is used for distributing the limited energy to the sensing process and the transmission process to maximize the data flow;
and the solving unit is used for exhaustively obtaining an optimal solution according to the limited sensing samples so as to obtain a frequency spectrum access result.
In a third aspect of the embodiments of the present invention, there is provided an electronic device, including a memory, a processor, and a computer program stored in the memory and executable by the processor, where the processor implements all or part of the steps of the method according to the first aspect of the embodiments of the present invention when executing the computer program.
In a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided, which stores a computer program that, when executed by a processor, implements all or part of the steps of the method provided by the first aspect of embodiments of the present invention.
In the embodiment of the invention, a multi-antenna full-duplex transceiver is equipped for a secondary user, and optimal energy distribution is carried out, so that sensing and transmission operations are realized, and higher capacity gain can be obtained; whether a master user is in an active state or not is designed, data transmission is carried out in an interweaving mode or a bottom layer mode, and a frequency spectrum can be flexibly sensed; considering the energy limitation and the mixed dynamic spectrum access of the main user conflict, the optimal solution is obtained through exhaustion, and the transmission flow can be improved. Meanwhile, continuous sensing sampling can be achieved, and the reliability of conflict detection is guaranteed.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic flowchart of a hybrid dynamic spectrum access method for a full-duplex cognitive wireless network according to an embodiment of the present invention;
FIG. 2 is a block diagram of a multi-band full-duplex cognitive radio according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating a discrete four-state frame structure according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of exhaustive search sampling according to an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons skilled in the art without any inventive work shall fall within the protection scope of the present invention, and the principle and features of the present invention shall be described below with reference to the accompanying drawings.
The terms "comprises" and "comprising," when used in this specification and claims, and in the appended drawings, are intended to cover non-exclusive inclusions, such that a process, method or system, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements.
It can be understood that, in the embodiment of the present invention, in order to overcome the defect of the half-duplex network, and to implement continuous sensing of the spectrum without switching between the sensing time slot and the data transmission time slot, a full-duplex cognitive wireless network is designed, so that the cognitive nodes can sense the spectrum at the same time and transmit data by using the radio frequency channel. The self-interference can be eliminated, and the flow of the wireless communication system is effectively doubled. Full duplex distributes traffic symmetrically along both directions of the bidirectional link, ensuring concurrent transmission and achieving maximum (2X) gain. Despite the presence of crosstalk, path loss, signal attenuation, internal interference between the transmitter (Tx) and receiver (Rx), the development of radio frequency circuit designs and beam forming antennas has prompted full duplex transmission in the same frequency band. Full-duplex transceivers require additional building blocks to eliminate self-interference (e.g., time domain methods, frequency domain methods and the use of circulators) and to compensate for in-phase and quadrature imbalances, but eliminate hidden station problems in competing networks, and provide greater agility to the network in response to environmental changes. For example, beamforming techniques in 5G networks, massive MIMO deployment, centralized architecture, and small cell design all facilitate full-duplex implementations. Smart device scheduling with appropriate rate and power allocation can achieve high capacity gain from full duplex operation.
The secondary users equipped with a plurality of full duplex transceivers are used to realize faster spectrum sensing and more effective dynamic spectrum access, and meet the complexity of clients at a hardware layer and the compatibility of a higher-layer traffic mode. By adopting a hybrid method of a bottom layer mode and/or an interleaving mode, the aim of optimizing the information rate of a secondary user under the energy limit is finally achieved aiming at keeping low cost, low power consumption and low complexity of user equipment, especially in the last kilometer.
Referring to fig. 1, fig. 1 is a schematic flow chart of a dynamic spectrum access method of a full-duplex cognitive wireless network according to an embodiment of the present invention, including:
s101, establishing a dual-channel radio frequency front end, a spectrum sensing module and a cognitive engine module, wherein the radio frequency front end comprises full duplex operation and control;
in one embodiment, as shown in fig. 2, multi-band operation is used as a combination of licensed and unlicensed bands for cognitive wireless networks. In consideration of channel damage and interference threats, the most favorable channel is selected for reliable operation by adopting multi-band and multi-channel operation, and a multi-band patch antenna, a dual-channel radio frequency front end, a broadband multi-channel spectrum sensing module, a cognitive engine and a baseband processing module are designed.
Wherein the radio frequency front end includes full duplex operation and control, transmitter and receiver parameter reconstruction, wide tuning range and multiband operation, integrated filter and minimum off-chip filter, and low noise low power design. With a direct conversion receiver, the signal is downconverted to baseband, eliminating the frequency and interference associated with a superheterodyne receiver. Transmitter and receiver parameters including center frequency, bandwidth, filter bandwidth, amplifier gain, transmit power, automatic gain control, etc. are configured according to the sensing results.
The spectrum sensing module, namely the broadband multi-channel spectrum sensing module, allocates broadband to a plurality of radio frequency channels, executes spectrum sensing in each channel, and combines results to cover a given broadband. In each frequency band, there are multiple channels in which multiple samples are collected, and for each channel, a Power Spectral Density (PSD) is calculated in frequency bin size. Spectrum sensing employs parallel detectors, such as energy detectors. And the signal-to-noise ratio estimation and the adaptive sampling are used for realizing reliable perception and calculating the probability of false alarm and collision detection.
The cognitive engine module, namely a cognitive engine and baseband processing module: and the cognitive engine processes the sensing result to adaptively configure the radio frequency front end, the baseband parameters and the frequency spectrum sensing module. In one aspect, a cognitive engine controls the coordination process between the sensing channel and the data transmission channel. The sensing channels are independently controlled, covering spectrum sensing in each frequency band. The channel occupation/vacancy detailed information is input into a lookup table, and then a proper data transmission channel is selected from the lookup table. Meanwhile, the parameters of the emitter and the receiver are self-adapted by the cognitive engine according to the perception result. On the other hand, the baseband processing module is in the baseband processing core and is used for configuring, controlling and transmitting data. Meanwhile, the baseband processing controls the data transmission channel, and dynamically configures packet length, inverse/fast fourier transform scale, cyclic prefix, and other parameters in the transmitter and the receiver.
S102, using a time slot strategy to divide time into a plurality of frames, determining a spectrum access state according to a sensing result in each frame, and establishing a bottom layer with limited energy or an interweaving mixed data transmission mode;
it should be noted that, although full-duplex communication brings many advantages, the industry rarely integrates it into commercial cellular and WiFi devices, and a full-duplex system cannot be deployed as widely as multi-user MIMO and other technologies. Therefore, N is designed and arranged in the embodiment of the invention s A receiver and N t Primary and secondary users of a transmitter antenna.
By adopting a plurality of full duplex antennas, the secondary user can simultaneously transmit and sense the activity of the primary user network, and self-interference is eliminated. The time slot strategy is used, time is divided into a plurality of frames, the spectrum range state is determined according to the sensing result in each frame, the wireless network is allowed to transmit in an interleaving mode or a bottom layer mode in a malformed mode, in the hybrid method, the cognitive wireless network optimizes the transmission mode on each frequency band based on interleaving or the bottom layer, and the maximum flow under actual constraint is met. The receiver of the secondary user can correctly decode the received signal regardless of whether the transmission is in the interleaved mode or the underlay mode. The transmission state in the secondary user receiver, transmitted through the backbone network, is determined by the energy of the received signal.
In one embodiment, fig. 3 shows a frame structure with a primary user in an inactive/active state and a secondary user in an underlay/interlace mode, where imperfect spectrum detection may result in poor spectrum access conditions when the primary user is in the inactive state, despite transmission errors in the underlay mode; when the primary user is in an active state, the detector basically cannot miss detection, and the interference between the primary user and the secondary user is indicated. The secondary users can then transmit in each band in a mixed mode: if the primary user is detected to be in an active state, the secondary user transmits data in a conservative bottom mode; if the primary user is detected to be inactive, the secondary user will take over the band completely and transmit data in the interleaved mode.
S103, acquiring energy consumption and sensing samples of a data sensing and data transmission stage;
the total available energy consists of the perceived consumed energy and the transmitted consumed energy. In the sensing stage, the consumed energy is proportional to the number of sampling bits, and the sensing result is improved as the number of samples is increased. The increase in energy during the transmission phase, where the receiver obtains the energy required for sampling or processing for different distances, path loss exponents, and channel transmission data, helps to improve channel capacity and throughput.
The four states of the primary user and the secondary user comprise: the primary user is in an inactive state, and the secondary user is in a bottom layer mode; the primary user is in an inactive state, and the secondary user is in an interleaving mode; the primary user is in an active state, and the secondary user is in a bottom layer mode; the primary user is in an active state and the secondary user is in an interleaved mode. The false alarm and collision detection probabilities in these states are different.
And obtaining perception samples according to different antenna numbers, sampling bit numbers, self-interference offset gains, channel responses among the antennas, antenna noise, a main user signal and secondary user self-interference. According to background noise of the antenna, main user signals and self interference of secondary users in a mixed mode, sensing sampling signals of different antennas obey independent zero-mean symmetric complex normal distribution in a sensing sampling state. The perception sampling signals of different antennas are independent, energy statistics is maximum invariant sufficient statistics, and the gamma distribution of shape parameters and scale parameters is achieved.
In particular, during the sensing phase, the power consumption of the semiconductor device is proportional to the clock frequency and the square of the supply voltage, so that the energy P consumed during the sensing phase s And the number m of sampling bits s In proportion, i.e. P s ＝m s p is the same as the above. The perceptual result improves with an increase in the number of samples, while, at the same time, an increase in the energy of the transmission phase helps to improve the capacity of the primary user channel,thereby increasing the flow rate.
During the transmission phase, the present invention sets a budget limit for the energy consumption within each frame. Transmitting b over a channel having a distance d and a path loss exponent η t Bit data. At the receiver, the energy required to sample and process the bits is m t p is the same as the formula (I). Suppose consumption of energy P a r η ＝m t (l-1) p and m t There is a linear relationship between them. Wherein E a Is the necessary power to radiate over a lossless distance, and
is the ratio of the energy consumed by each bit of radiation to the energy consumed by the sensing, let P t Is the energy consumed by the transmission, the total available energy P is set to be a constant, P is the minimum unit of P, and then
The total available energy comprises the perceived consumed energy (P) s ) And transferring the consumed energy (P) t ) I.e. by
Where all of the total available energy is Hp. Set K to round to an integer, therefore have
As shown in fig. 3, four possible states of the primary user and the secondary user are given:
indicating that the primary user is in an inactive state, the secondary user is in a bottom layer mode,
indicating that the primary user is inactive, the secondary user is in an interlace mode,
indicating that the primary user is active, the secondary user is in the bottom layer mode,
indicating that the primary user is active and the secondary user is in an interlace mode. In these states, the probability of false alarm and collision detection are different.
Let i be the number of antennas, n be the number of sampling bits, further let f (i, n) be the flow of the sampled signal sensed by the ith antenna for the nth time, g be the self-interference cancellation gain, r p (i) Channel response between the i-th antenna of the primary user, r s (i) Is the transmission response (r) to the ith antenna of the secondary user p (i) And r s (i) V (i, n) is the noise of the ith antenna, y, in each time frame and known to the primary and secondary users p (n) is a primary user signal, y s (n) is the self-interference of the secondary user. Where PU =1 and PU =0 respectively indicate whether the primary user is active or inactive. Among all subscripts, a subscript p represents a primary user, a subscript s represents a secondary user, and the subscript s 0 And subscript s 1 Indicating that the secondary user is in the underlay mode and the interlace mode, respectively, and the subscript v indicates noise. Four perceptual samples are then obtained:
state of state
State of state
Status of state
Status of state
Full duplex faces problems due to traffic asymmetry between uplink and downlink on higher layers. In particular, full duplex requires that traffic be distributed symmetrically along both directions of the bidirectional link to ensure concurrent transmission and obtain maximum (2X) gain. Setting independent zero-mean symmetric white complex normal distribution:
thus, in four perceptual sampling states there are:
status of state
Status of state
State of state
Status of state
Random flow f (i, 1), …, f (i, m) s ) Energy statistics can be found by independently and identically distributing under four possible states
Is a maximum invariant sufficient statistic, and has Gamma distributions p (i) to Gamma (p (i), theta (i)), and a probability density function of
The shape parameter is (m) s >0) Dimension parameter (θ (i)>0) In the four perceptual sampling states:
status of state
State of state
Status of state
Status of state
S104, respectively calculating the false alarm and conflict detection probabilities in different modes;
specifically, a joint probability density function of energy statistics is obtained by combining the number of receivers, and average energy statistics is obtained by using an energy detector according to a distance threshold of a bottom layer mode and a distance threshold of an interleaving mode. The sampled normal distribution accurately approximates the probability density function of the mean energy statistic by means of the central limit theorem.
Wherein the different mode false alarm and collision detection probabilities include: the probability of false alarm when the secondary user is in the interleaving mode, the probability of false alarm when the secondary user is in the bottom layer mode, the probability of collision detection when the secondary user is in the interleaving mode, and the probability of collision detection when the secondary user is in the bottom layer mode.
In one embodiment, the number of combined receivers N s The joint probability density function of the energy statistics p (i) is
Let d be 0 Distance threshold for the underlying mode, d 1 For distance threshold of the interleaved mode, the present embodiment uses an energy detector to obtain average energy statistics
For the number m of sampling bits s When the secondary user adopts the interleaving mode, m s Is equal to m s1 (ii) a When the secondary user adopts the underlying mode, m s Is equal to m s0 . Thus, P can be found ED As an accurate representation of the sum of the independent gamma distribution random variables. However, since N is actually sampled s m s Is large, the above normal distribution needs to accurately approximate P using the central limit theorem ED Is determined. Let subscript f denote false alarm, subscript c denote collision detection, subscript 0 denote that the secondary user is in the bottom layer mode, subscript 1 denote that the secondary user is in the interlace mode, and the probabilities under four conditions are calculated as follows:
S105, establishing a full-duplex discrete four-state Markov transfer model;
based on the four-state Markov transition process, a transition rule is derived from the two-state model. The flow conditions include three conditions: when the primary user is in an active state and the secondary user is in a bottom layer mode; when the primary user is in an inactive state and the secondary user is in an interleaving mode; when the primary user is in an inactive state and the secondary user is in the underlying mode.
The wrong primary user detection result can generate flow, so that the frequency spectrum cannot be effectively utilized. The average flow is given by the false alarm flow and the conflict detection flow, and changes along with the probability that the frequency spectrum lacks the primary user and the probability that the frequency spectrum has the primary user. The average traffic depends on the detection threshold and the number of perceptual samples in the underlying and interleaved states. Since the perceptual sample is a finite integer, the present embodiment may find the best solution through an exhaustive search.
In one embodiment, a four-state Markov transfer model is presented, having P for primary and secondary users ij The probabilities of SU = i and PU = j are indicated. PU =1 and PU =0 indicate whether the primary user is active or inactive, respectively. Further, SU =0 and SU =1 indicate that the secondary user is in the underlay mode or the interlace mode, respectively. From these two-state models, a transformation rule (1) is derived:
conversion rule (2):
according to the rule, the following results are obtained:
status of state
State of state
Status of state
Status of state
There is flow in 3 of the above 4 states: when the primary user is in active state and the secondary user is in bottom layerIn the mode; when the primary user is in an inactive state and the secondary user is in an interlace mode; when the primary user is in an inactive state and the secondary user is in the underlying mode. State 3 is the result of a false primary user detection. In this undesirable situation, some traffic is brought in, and the spectrum is not used efficiently. The average flow (F) is thus determined by the false alarm flow (F) c ) And collision detection traffic (F) f ) Two parts are given, i.e. F = F c +F f Let xi 0 Probability of spectrum lacking primary user, ξ 1 For the probability of the existence of primary users in the frequency spectrum, there are
S106, distributing the limited energy to sensing and transmission to maximize flow;
limited energy is efficiently allocated to sensing and transmission to maximize traffic. The cognitive radio network meets the requirement of error probability, and for each transmission mode, minimum detection probability and maximum false alarm probability constraint are set. Aiming at the probability of false alarm and conflict detection under four conditions, as well as the false alarm flow and the conflict detection flow, the objective function of the optimization problem is the maximized average flow, and the constraint condition is the probability constraint under the four conditions of combining the false alarm/conflict detection and the interweaved design/bottom layer design.
Optionally, the optimization problem is converted into a simple convex optimization, the first derivative is negative, and inequality constraints of distance thresholds in the interleaving and bottom layer design are given and expressed as convex rectangles. The false alarm flow rate increases with the distance threshold in the interlace design/floor design; in contrast, the collision detection traffic decreases with the distance threshold in the interlace design/underlay design. Thus, it is necessary to optimize the two distance thresholds and find a potential condition that makes the average flow rate convex.
In particular, cognitive wireless networks must meet certain requirements for error probability. Thus, for each transmission mode, one mayTo assume constraints on the minimum detection probability and the maximum false alarm probability. Order to
In order to be a false alarm probability threshold value,
is a detection probability threshold. Combining the probability of false alarm and conflict detection under four conditions, as well as the false alarm flow and the conflict detection flow, and optimizing the objective function of the problem to be the sub-user bottom layer mode
And secondary user interleaving mode
Lower maximum average flow F (d) 0 ,d 1 ) The constraint is the probability in the four cases of designing the base layer and the interleaving in combination with false alarm and collision detection, i.e. the constraint
The optimization problem is now converted into a simple convex optimization problem. Since the first derivatives are all negative, the inequality constraints in the optimization problem can be rewritten
And represents a convex rectangle. Hence, the false alarm flow rate F d With the bottom layer in the mixed mode and the threshold (d) in the interleaved design 0 And d 1 ) Increasing; in contrast, the collision detection flow rate F d With d 0 And d 1 And decreases. This triggers optimization of d 0 And d 1 And find a potential condition for F to be convex. Thus, considering that the blackplug matrix H of-F is positive and semi-definite, F is convex, which requires that all minimum determinants of H are positive.
And S107, exhaustively obtaining an optimal solution according to the limited sensing sample to obtain a frequency spectrum access result.
The traffic in false alarm and collision detection is convex with respect to the thresholds in the interleaving and underlying design. Also, the determinant of the blackplug matrix is positive for the thresholds in the interleaving and the underlying design. An exhaustive search numerical method is used to ensure that the flow reaches a global maximum. Traffic is represented as a function of probability of false alarm and collision detection, detection threshold, allocated power. The constraint is convex and the flow is a concave function with a global optimum. And finding a convex condition for defining an optimization problem, and searching a flow function under the limited energy resource.
In particular, the flow in false alarm and collision detection is relative to d 0 And d 1 Is convex. And, determinant of black plug matrix H to d 0 And d 1 Is positive. Thus, the following convex problem can be rewritten: the objective function is in the sub-user bottom mode
And secondary user interlace mode
Lower maximum average flow
The constraint is the threshold (d) in the underlying and interleaved designs 0 And d 1 ) And (4) limiting. Using the exhaustive search numerical method shown in fig. 4, it is possible to ensure that the flow reaches a global maximum.
Traffic is represented as a function of probability of false alarm and collision detection, detection threshold, allocated power. It has been shown that the constraints are all convex, while the flow is a concave function (the problem is equivalent to the convex optimization problem) and has a unique global optimum. Concave conditions defining the optimization problem are found to find a flow function under a limited energy resource. In order to achieve global optimization of the parameters, corresponding threshold conditions are obtained, and then optimal points of energy distribution are obtained.
In the sampling process, firstly, the maximum average flow is initialized, and the maximum secondary usage is initializedThe number of channel transmission bits in the user interlace mode/underlay mode. Then, respectively in the sub-user bottom layer mode
And secondary user interlace mode
Then, the number of cycles from 1 to the maximum value was counted, and a double cycle was performed. Specifically, the number of channel transmission bits in the secondary user base layer mode/interlace mode needs to be fixed to obtain the current maximum flow (F), then, whether the current maximum flow is greater than the recorded maximum flow is judged, if so, the recorded maximum flow is updated, and the number of channel transmission bits in the secondary user base layer mode/interlace mode is saved. And finally, returning the recorded maximum flow (F) and returning the stored channel transmission bit number under the bottom layer mode/the interleaving mode.
Compared with the prior art, the method provided by the implementation has the following beneficial effects: the secondary users are equipped with multi-antenna full-duplex transceivers to achieve both sensing and transmission operations by optimally allocating energy to achieve higher capacity gains. A new hybrid access sub-formula is designed to transmit in an interleaved and/or underlay mode to flexibly sense spectrum regardless of whether a primary user is active. And the energy limit and the conflicting hybrid dynamic spectrum access of the main user are jointly considered, and the flow is improved to the maximum extent through exhaustive search.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by functions and internal logic of the process, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
In another embodiment, there is also provided an apparatus for hybrid dynamic spectrum access for a full-duplex cognitive wireless network, the apparatus comprising:
the system comprises a construction unit, a spectrum sensing module and a cognitive engine module, wherein the construction unit is used for constructing a dual-channel radio frequency front end, the spectrum sensing module and the cognitive engine module, and the radio frequency front end comprises full duplex operation and control;
the device comprises an establishing unit, a time slot determining unit and a data transmission unit, wherein the establishing unit is used for dividing time into a plurality of frames by using a time slot strategy, determining a spectrum access state according to a sensing result in each frame, and establishing a data transmission mode of a bottom layer with limited energy and interweaving;
the acquisition unit is used for acquiring energy consumption and sensing sampling of a data sensing stage and a data transmission stage;
the calculating unit is used for respectively calculating the probability of false alarm and collision detection in different modes;
the model building unit is used for building a full-duplex discrete four-state Markov transfer model;
the distribution unit is used for distributing the limited energy to the sensing process and the transmission process to maximize the data flow;
and the solving unit is used for exhaustively obtaining an optimal solution according to the limited sensing sample so as to obtain a frequency spectrum access result.
It will be appreciated that in one embodiment, the electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor that, when executed, enables hybrid dynamic spectrum access for a full-duplex cognitive wireless network with respect to energy constraints and primary user collisions. Those skilled in the art will also understand that all or part of the steps in the method according to the above embodiments may be implemented by hardware that is related to instructions of a program, and the program may be stored in a computer-readable storage medium, such as ROM/RAM.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A hybrid dynamic spectrum access method of a full-duplex cognitive wireless network is characterized by comprising the following steps:
establishing a dual-channel radio frequency front end, a spectrum sensing module and a cognitive engine module, wherein the radio frequency front end comprises full duplex operation and control;
dividing time into a plurality of frames by using a time slot strategy, determining a spectrum access state according to a sensing result in each frame, and establishing a data transmission mode of a bottom layer with limited energy and interweaving;
wherein the establishing of the data transmission mode of the energy-limited bottom layer and the interleaving mixture comprises the following steps:
the secondary user transmits in a mixed mode in each frequency band, if the primary user is detected to be in an active state, the secondary user transmits data in a bottom layer mode, and if the primary user is detected to be in an inactive state, the secondary user takes over the frequency band completely and transmits the data in an interleaving mode;
acquiring energy consumption and perception sampling of a data perception stage and a data transmission stage;
respectively calculating the probability of false alarm and collision detection in different modes;
establishing a full-duplex discrete four-state Markov transfer model;
distributing limited energy to a sensing process and a transmission process to maximize flow;
and exhaustively obtaining an optimal solution according to the limited sensing samples to obtain a spectrum access result.
2. The method of claim 1, wherein the spectrum sensing module comprises:
performing spectrum sensing in each channel, and combining sensing results to cover a given broadband;
a plurality of samples are collected in a channel, and a power spectral density is calculated in a frequency bin size for each channel.
3. The method of claim 1, wherein obtaining energy consumption and perceptual samples for a data sensing phase and a data transmission phase comprises:
under a sensing sampling state, sensing sampling signals of different antennas follow independent zero-mean symmetrical complex normal distribution; the perception sampling signals of different antennas are independently and identically distributed, and energy statistics is provided with shape parameters and gamma distribution of the size parameters.
The four states of the primary user and the secondary user comprise: the primary user is in an inactive state, and the secondary user is in a bottom layer mode; the primary user is in an inactive state, and the secondary user is in an interleaving mode; the primary user is in an active state, and the secondary user is in a bottom layer mode; the primary user is in an active state and the secondary user is in an interlace mode.
4. The method of claim 1, wherein the calculating the false alarm and collision detection probabilities in different modes respectively comprises:
obtaining a joint probability density function of energy statistics by combining the number of receivers, and obtaining average energy statistics by using an energy detector according to a distance threshold of a bottom layer mode and a distance threshold of an interleaving mode;
the probability density function of the average energy statistics is accurately approximated using the central limit theorem.
5. The method of claim 1, wherein establishing a full-duplex discrete four-state markov transition model comprises:
obtaining Markov transfer processes in four states according to the fact that a secondary user is in an interweaving or bottom layer mode and a primary user is in an active or inactive state;
the average flow is calculated according to the false alarm flow and the conflict detection flow, and changes in probability along with the lack or existence of a master user in a frequency spectrum.
6. The method of claim 1, wherein the allocating limited energy to sensing and transmission processes, maximizing traffic comprises:
limited energy is distributed to a sensing process and a transmission process, the probability of false alarm and conflict detection is combined, an objective function of an optimization problem is set to be the maximum average flow under a secondary user bottom layer mode and a secondary user interweaving mode, and constraint conditions are set to be probability constraint under four conditions of false alarm, conflict detection and mixed mode.
7. The method of claim 1, wherein the exhaustively deriving an optimal solution from the finite perceptual sample comprises:
representing traffic as a function of probability of false alarm and collision detection, detection threshold, allocated power;
initializing the maximum average flow and the channel transmission digit in the maximum secondary user mixed mode, and respectively obtaining the current maximum flow and the stored channel transmission digit in the mixed mode in the secondary user interweaving mode and the secondary user bottom mode.
8. An apparatus for hybrid dynamic spectrum access for a full-duplex cognitive wireless network, comprising:
the system comprises a construction unit, a spectrum sensing module and a cognitive engine module, wherein the construction unit is used for constructing a dual-channel radio frequency front end, the spectrum sensing module and the cognitive engine module, and the radio frequency front end comprises full duplex operation and control;
the device comprises an establishing unit, a time slot determining unit and a data transmission unit, wherein the establishing unit is used for dividing time into a plurality of frames by using a time slot strategy, determining a spectrum access state according to a sensing result in each frame, and establishing a data transmission mode of a bottom layer with limited energy and interweaving;
the acquisition unit is used for acquiring energy consumption and sensing sampling of a data sensing stage and a data transmission stage;
the calculating unit is used for respectively calculating the probability of false alarm and collision detection in different modes;
the model building unit is used for building a full-duplex discrete four-state Markov transfer model;
the distribution unit is used for distributing the limited energy to the sensing process and the transmission process to maximize the data flow;
and the solving unit is used for exhaustively obtaining an optimal solution according to the limited sensing sample so as to obtain a frequency spectrum access result.
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