CN109982438A - A kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment - Google Patents
A kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/542—Allocation or scheduling criteria for wireless resources based on quality criteria using measured or perceived quality
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The present invention relates to a kind of multi-user resource distributing methods based under NOMA and SWIPT cognitive radio environment, run on based on multi-user's relay communications system under NOMA and SWIPT cognitive radio environment, including PU, m relaying R of a primary user1~Rm, two user's transmitting terminal ST1And ST2And one user receiving end SR, primary user PU are in communications status always；Increasing system user can access quantity, improve the frequency effect and efficiency of system.Complicated non-convex problem is converted to the linear programming problem for being easy to solve by the method for seeking optimal solution using traversal, final to realize the achievable rate for maximizing weak user in two grade network.
Description
Technical field
The present invention relates to one kind based on NOMA (simultaneous interpretation of wireless messages energy) and SWIPT (non-orthogonal multiple) cognitive radio
Multi-user resource distributing method under environment belongs to art communication systems field.
Background technique
With the appearance of 5G, geometric increase, the scarcity and use of frequency spectrum resource is presented in the demand of mobile device access
Family forms contradiction to the bigger demand of rate.NOMA can greatly improve spectrum efficiency, realize and be multiplexed in power domain,
Increase while user accesses quantity and reduce transmission delay, therefore receives more and more attention.The basic thought of NOMA is
Non orthogonal transmissions are used in transmitting terminal, different users shows different power differences in receiving end, actively introduces interference letter
Breath then realizes the correct demodulation of different user information using serial interference elimination (SIC).
Cognitive radio (CR) is considered as the most promising technology for solving current spectral underutilization of resources.The root of CR
This purpose is shared frequency spectrum, and secondary user's (unauthorized user) makes full use of primary user (authorized user) frequency spectrum to communicate, simultaneously
The influence for ensuring that the service quality (QoS) of primary user is unaffected or being subject to is lower than certain limit.There are two types of frequency spectrums to access at present
Mode covers (overlay) mode and bottom (underlay) mode.For covering pattern, secondary user needs to perceive primary user
Frequency spectrum and at primary user's free time access for communication frequency spectrum.Once primary user has communicating requirement, secondary user needs end
The process only communicated exits frequency spectrum access.For bottom mode, secondary user still accesses frequency when primary user is in communications status
Spectrum, still, interfering caused by primary user in secondary user's communication period must control within the acceptable range.
The it is proposed of wireless messages energy simultaneous interpretation (SWIPT) is to improve system energy efficiency to bring huge hope.SWIPT by pair
Radio frequency (RF) signal received at receiving end executes dynamic power distribution (DPS) strategy, and the radiofrequency signal received is divided into
Two parts, a part are used for energy stores, and another part is for decoding.Receiving device is it using the RF energy in environment
Electric energy itself is provided, the use of this technology can greatly prolong the service life of wireless network node, be difficult to especially for some
The low power consuming devices to charge in time.
The emphasis of resource allocation research under existing multi-user communication scene often focuses on the distribution of frequency spectrum or power,
The handling capacity of system or achievable rate is made to reach maximum or bit error rate minimum etc. by certain optimisation strategy.Optimize past
Toward the resource for concentrating on single dimension, and most of the cases only considers that base station to the downlink transfer of user, is provided between user
Source distributional equity takes into account deficiency, and few work for optimizing frequency spectrum and power distribution joint consideration.And incite somebody to action
The two combines, and the utilization rate of resource and the access amount of user will be increased in multiple.This is rare in the communication resource, user
Measure rapid growth is great research significance instantly.
There are some researchs in terms of cognitive radio and non-orthogonal multiple and wireless messages energy simultaneous interpretation now,
There are a small number of researchs for combining non-orthogonal multiple and cognitive radio.The appearance of NOMA technology be substantially to related communication resource into
Row non-orthogonal multiplexing, so that more users make full use of resource instantly in the form of non-orthogonal, and the introducing of multi-user is providing
The fairness problem between user is certainly existed in the distribution of source.In traditional NOMA mode, the use with good channel conditions
Family is assigned more transimission powers, and there is the user of the channel condition of difference to be assigned less transimission power.This mode
The fairness between user is had ignored, the achievable rate that may cause weak user (WU) is too low, and then decodes failure.
Summary of the invention
In view of the deficiencies of the prior art, the present invention provides a kind of based under NOMA and SWIPT cognitive radio environment
Multi-user resource distributing method；
The present invention has studied the performance of multi-user's relay communications system under cognitive radio environment.Mould used in the present invention
Formula is the mode of bottom access frequency spectrum.The present invention combines CR, NOMA and SWIPT, and proposes a kind of power distribution algorithm,
Consider to maximize in two grade network (network composed by secondary user) in the case where uplink and downlink transmission at the same time
The achievable rate of weak user.
Assuming that channel state information (CSI) is it is known that compared with traditional NOMA static power allocation strategy, the present invention is comprehensive
Consider that the channel condition of uplink and downlink transmission optimizes time transmission power of user and the power allocation factor of relaying.And it is arranged
Minimum Signal to Interference plus Noise Ratio (SINR) thresholding that strong user (SU) can be correctly decoded, to ensure at least one in two users
It can be correctly decoded.By optimizing transmission power, and the power allocation factor of relaying, reach the WU achievable rate in two grade network
To maximum.The present invention can not only increase the access quantity of secondary user, improve the spectrum efficiency of system, and combine
Fairness between user.
The technical solution of the present invention is as follows:
A kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment, runs on and is based on
Multi-user's relay communications system under NOMA and SWIPT cognitive radio environment, including PU, m relaying R of a primary user1~
Rm, two user's transmitting terminal ST1And ST2And one user receiving end SR, wherein assuming that primary user PU is in logical always
Letter state；
Since not secondary user's transmitting terminal (ST) arrives the direct access path of time user receiving end (SR), the signal of secondary user needs
Forwarding (AF) is amplified by relaying, relaying can execute dynamic power segmentation in the process, utilize the radio frequency energy being collected into
Amount is next forward signal service.In actual scene, transmitting terminal and receiving end often have fixed energy source, however
Quantity is more, distribution is wide, working environment is complicated, is difficult the characteristics of being charged in time due to having for relaying, it is assumed that it is not solid
Fixed energy source.Therefore, present invention adds energy to gather in link, will communicate temporally between secondary user's transmitting terminal and relaying
It is divided into two isometric stages, in time first stage, two times user's transmitting terminals send radiofrequency signal simultaneously, and relay reception is penetrated
Frequency signal simultaneously carries out energy harvesting；In the second stage time, relaying will execute residue after energy harvesting in time first stage
Signal be forwarded, the energy for forwarding is provided by the energy that is collected into stage first time；It comprises the following steps that
(1) interference of the two grade network work to primary user PU: two grade network includes two user's transmitting terminal ST1And ST2、m
A relaying R1~RmAnd one user receiving end SR, as two user's transmitting terminal ST1And ST2It sends in signal process,
Seek the interference I that primary user PU in stage first time is subject to1, I2, respectively as shown in formula (I), formula (II):
In formula (I), formula (II), P1Indicate time user's transmitting terminal ST1Transmission power, P2Indicate time user's transmitting terminal ST2's
Send power, dU, 1Indicate primary user PU to time user's transmitting terminal ST1Distance, dU, 2Indicate primary user PU to time user's transmitting terminal
ST2Distance, lU, 1Indicate primary user PU and time user's transmitting terminal ST1Between channel gain, lU, 2Indicate primary user PU and time use
Family transmitting terminal ST2Between channel gain, θ is path-loss factor；
Seek relaying RiI is interfered caused by primary user PU during forward signal3, as shown in formula (III):
In formula (III),It is primary user PU and relaying RiThe distance between, kiPrimary user PU is represented to relaying Ri's
Channel gain；Indicate that transmission power when the second time phase relay forwarding signal, θ are path-loss factor；
Under underlay mode, two grade network needs to control in certain threshold value I to the interference of primary userthIt is interior, therefore have,
I1≤Ith, I2≤Ith, I3≤Ith。
(2) weak user ST in two grade network is calculatedjAchievable rate:It is presented at receiving end in the present invention
High-power user is referred to as strong user SU, and the user that low-power is presented at receiving end is referred to as weak user WU, therefore strong user
It can be expressed as ST3-j；It acquires and respectively obtains time user's transmitting terminal ST in secondary user receiving end SR1With ST2The power of useful signal,
S is used respectively1, i, S2, iIt indicates, seeks the noise power N of time user receiving end SRi, respectively such as formula (IV), formula (V), formula (VI) institute
Show:
Formula (IV), formula (V), in formula (VI), η, η ∈ [0,1], the energy conversion efficiency of indication circuit, ρi∈ [0,1], under
Marking i indicates i-th of relaying, ρiIndicate power allocation factor when i-th of relaying executes energy harvesting, P1, P2Respectively indicate ST1
And ST2Transmission power, hI, 1, hI, 2Respectively indicate ST1To Ri、ST2To RiSmall scale rayleigh fading channel channel gain,
dI, 1, dI, 2Respectively indicating indicates RiTo ST1、RiTo ST2Distance, θ be the path loss factor, giIndicate RiTo the channel gain of SR,
It is RiThe distance between SR；The normalized power of the white Gaussian noise introduced when receiving signal for SR,It is PU to Ri's
Jamming power,For RiThe white Gaussian noise power introduced in receiving signal process,To relay RiDuring forward signal
The white Gaussian noise power introduced from frequency band to base band；
It needs first to decode high-power user when decoding NOMA signal, then decodes low-power using serial interference elimination
User.Therefore it needs to be determined that ST1With ST2Decoding order.Determine ST1With ST2Who is more suitable for strong user or weak use
Family.However who can not be directly determined out according to formula (X), formula (XI), formula (XII) and be more suitable for strong user or weak user.
In the case where two users' access, STjIndicate that weak user, j ∈ { 1,2 }, strong user are expressed as ST3-j, it is contemplated that it uses
Fairness problem between family, is arranged Signal to Interference plus Noise Ratio threshold value τ, and Signal to Interference plus Noise Ratio threshold value τ is that letter required for user is correctly decoded is dry
It makes an uproar the minimum value of ratio, therefore, strong user ST3-jSignal to Interference plus Noise Ratio SINRHShown in the condition of satisfaction such as formula (VII):
In formula (VII), j is 1 or 2,1≤i≤m；
When the Signal to Interference plus Noise Ratio of strong user meets formula (VII), weak user obtains decoded chance, and the letter for seeking weak user is dry
It makes an uproar and compares SINRL, as shown in formula (VIII):
Final purpose of the invention is in two grade network, and the decoded premise of guarantee one energy increases access customer number, and
Enable the achievable rate of WU to reach maximum, therefore, seeks the achievable rate R of weak userL, as shown in formula (IX):
(3) combined optimization sends power, function molecular group and relay selection algorithm, and objective function is formula (IX), limits item
Part C1-C6 is as follows:
st.C1 I1+I2≤Ith
C3 SINRH≥τ
C4 0≤ρi≤1
C5 0≤P1≤P1max
C6 0≤P2≤P2max
IthThe jamming margin born by primary user PU under bottom access module；
C1 indicates that interference control is under jamming margin within stage first time；
C2 indicates that the second time phase relaying controls under jamming margin the interference of primary user；
C3 indicates the condition that the Signal to Interference plus Noise Ratio of strong user meets；
C4 indicates the value limitation of power splitting factor, realisation according to actual physics；
C5, C6 give the limitation that time user's transmitting terminal sends power,
It notices and works as ρiWhen fixed, noise power NiConstant will be become, the achievable rate of weak user is only with two users'
Send power P1And P2It is related, therefore, select to power splitting factor ρiIt is traversed, entire optimization problem is known as linear programming
Step delta ρ is arranged, respectively in ST in problem1With ST2It is calculated in the case where as weak user, chooses weak user's achievable rate most
One group of big solution is as optimal solution；
The selection of relaying and the selection of weak user are indicated as shown in formula (X), formula (XI):
In formula (X), formula (XI), by being traversed to each relaying, so that the achievable rate of weak user reaches maximum, i*
Indicate optimal relaying, j*Indicate time user ST1, ST2In the weak user WU that is more suitable for.
Preferred according to the present invention, in time first stage, two times user's transmitting terminal sends radiofrequency signal simultaneously, relays
It receives radiofrequency signal and carries out energy harvesting；In the second stage time, relaying will execute energy harvesting in time first stage
Remaining signal is forwarded afterwards, and the energy for forwarding is provided by the energy being collected into stage first time；Including step
It is rapid as follows:
A, transmission process: stage first time: within stage first time, two user's transmitting terminal ST1And ST2Simultaneously
Signal is sent, R is relayediIt is activated and receives signal, 1≤i≤m, this will interfere PU during signal transmits.In order to prominent
The principal contradiction to go wrong, we will suitably simplify problem.Ignore for when executing collection of energy, relaying RiCircuit energy
Consumption, and assume that the distance between SR and PU are far, ignore in the interference caused by SR of PU communication period, as shown in formula (XII):
In formula (XII),Indicate the signal that relay reception is sent to time user, hI, 1It is time user's transmitting terminal ST1To relaying
RiSmall scale rayleigh fading channel, hI, 2It is time user's transmitting terminal ST2To relaying RiSmall scale rayleigh fading channel, dI, 1Table
Show relaying RiTo secondary user's transmitting terminal ST1Distance, dI, 2Indicate relaying RiTo secondary user's transmitting terminal ST2Distance, θ be path loss because
Son；aiIndicate PU to RiInterference, Gaussian distributed It is PU to RiJamming power, uiIndicate Gauss
White noise, x1, x2Respectively indicate ST1, ST2Transmitted power normalization signal, all channels are set as independent with the letter divided
Road gain is the Rayleigh stochastic variable of 0dB；
Relay RiAfter receiving signal, R is relayediPower segmentation is carried out, part signal is used for energy storage, and part signal is for turning
Hair；
B, the second time phase: relaying RiSignal is sent to secondary user receiving end SR, what secondary user receiving end SR was received
Shown in signal such as formula (XIII):
In formula (XIII), giIndicate relaying RiTo the channel gain of SR,Indicate relaying RiWith secondary user receiving end SR it
Between distance, c indicates the white Gaussian noise introduced when time user receiving end SR receives signal,
It is further preferred that power is divided, refer to:
By power splitter, power allocation factor ρ is seti, ρi∈ [0,1], subscript i represent i-th of relaying, and signal is divided into
Two parts, the energy of energy storage, i.e. relaying RiThe ENERGY E being collected intoiAs shown in formula (XIV):
In formula (XIV), η indicates the energy conversion efficiency of RF energy collecting circuit, η ∈ [0,1]；The portion of energy will be by
For forward signal, R is relayediTransmission powerAs shown in formula (XV):
For the terseness of expression, so thatRelay RiIt connects
Get off to execute the link of amplification forwarding signal, signal amplification factor wi, as shown in formula (XVI):
In formula (XVI), biIndicate signal in relaying RiBy the frequency band white Gaussian noise introduced into base band conversion processes,Due to the very little compared with signal power to be forwarded, so being omitted in formula (4).Signal to be forwardedAnd noise biIt is all amplified in repeating process, therefore RiIn the signal such as formula of the second time phase forwarding
(XVII) shown in:
The invention has the benefit that
1, a kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment of the present invention, increases
User accesses quantity, improves the frequency effect and efficiency of system.
2, the present invention is based on the multi-user resource distributing method under NOMA and SWIPT cognitive radio environment, consider simultaneously
The power consumption issues of trunking increase energy harvesting module, environmentally protective.
3, the present invention analyzes power distribution and relay selection problem in two grade network between user, full in strong user
So that the achievable rate of weak user is reached maximum in the case where sufficient decoding requirements as far as possible, takes into account the fairness between user.
Detailed description of the invention
Fig. 1 is that the present invention is based on the models of multi-user's relay communications system under NOMA and SWIPT cognitive radio environment
Schematic diagram；
Fig. 2 is to execute proposed algorithm to relay in the different achievable rates sent under power limits from random selection with interference
The schematic diagram of the variation of tolerance；
Fig. 3 is to execute proposed algorithm to relay in the different achievable rates sent under power limits from random selection with decoding
The schematic diagram of the variation of demand；
Specific embodiment
The present invention is further qualified with embodiment with reference to the accompanying drawings of the specification, but not limited to this.
Embodiment 1
A kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment, runs on and is based on
Multi-user's relay communications system under NOMA and SWIPT cognitive radio environment, as shown in Figure 1, including primary user PU, a m
A relaying R1~Rm, two user's transmitting terminal ST1And ST2And one user receiving end SR, primary user PU are in always
Communications status；
Due to not secondary user's transmitting terminal to the direct access path of time user receiving end, the signal needs of secondary user pass through relaying
Forwarding (AF) is amplified, relaying can execute dynamic power segmentation in the process, be to connect down using the RF energy being collected into
The forward signal service come.In actual scene, transmitting terminal and receiving end often have fixed energy source, however relay due to
Have that quantity is more, distribution is wide, working environment is complicated, is difficult the characteristics of being charged in time, it is assumed that its energy for not fixing
Source.Therefore, present invention adds energy to gather in link, is temporally divided into two for communicating between secondary user's transmitting terminal and relaying
In a isometric stage, in time first stage, two times user's transmitting terminals send radiofrequency signal simultaneously, and relay reception radiofrequency signal is simultaneously
Carry out energy harvesting；In the second stage time, relaying will have been executed in the time first stage energy harvesting after remaining signal into
Row forwarding, the energy for forwarding are provided by the energy being collected into stage first time；It comprises the following steps that
(1) interference of the two grade network work to primary user PU: two grade network includes two user's transmitting terminal ST1And ST2、m
A relaying R1~RmAnd one user receiving end SR, as two user's transmitting terminal ST1And ST2It sends in signal process,
Seek the interference I that primary user PU in stage first time is subject to1, I2, respectively as shown in formula (I), formula (II):
In formula (I), formula (II), P1Indicate time user's transmitting terminal ST1Transmission power, P2Indicate time user's transmitting terminal ST2's
Send power, dU, 1Indicate primary user PU to time user's transmitting terminal ST1Distance, dU, 2Indicate primary user PU to time user's transmitting terminal
ST2Distance, lU, 1Indicate primary user PU and time user's transmitting terminal ST1Between channel gain, lU, 2Indicate primary user PU and time use
Family transmitting terminal ST2Between channel gain, θ is path-loss factor；
Seek relaying RiI is interfered caused by primary user PU during forward signal3, as shown in formula (III):
In formula (III),It is primary user PU and relaying RiThe distance between, kiPrimary user PU is represented to relaying Ri's
Channel gain；Indicate that transmission power when the second time phase relay forwarding signal, θ are path-loss factor；
(2) weak user ST in two grade network is calculatedjAchievable rate:It is presented at receiving end high-power
User is referred to as strong user SU, and the user that low-power is presented at receiving end is referred to as weak user WU, and strong user is expressed as ST3-j；It asks
It obtains and respectively obtains time user's transmitting terminal ST in secondary user receiving end SR1With ST2The power of useful signal, uses S respectively1, i, S2, iTable
Show, seeks the noise power N of time user receiving end SRi, respectively as shown in formula (IV), formula (V), formula (VI):
Formula (IV), formula (V), in formula (VI), η, η ∈ [0,1], the energy conversion efficiency of indication circuit, ρi∈ [0,1], under
Marking i indicates i-th of relaying, ρiIndicate power allocation factor when i-th of relaying executes energy harvesting, P1, P2Respectively indicate ST1
And ST2Transmission power, hI, 1, hI, 2Respectively indicate ST1To Ri、ST2To RiSmall scale rayleigh fading channel channel gain,
dI, 1, dI, 2Respectively indicating indicates RiTo ST1、RiTo ST2Distance, θ be the path loss factor, giIndicate RiTo the channel gain of SR,
It is RiThe distance between SR；The normalized power of the white Gaussian noise introduced when receiving signal for SR,It is PU to Ri's
Jamming power,For RiThe white Gaussian noise power introduced in receiving signal process,To relay RiDuring forward signal
The white Gaussian noise power introduced from frequency band to base band；
It needs first to decode high-power user when decoding NOMA signal, then decodes low-power using serial interference elimination
User.Therefore it needs to be determined that ST1With ST2Decoding order.Determine ST1With ST2Who is more suitable for strong user or weak use
Family.However who can not be directly determined out according to formula (X), formula (XI), formula (XII) and be more suitable for strong user or weak user.
In the case where two users' access, STjIndicate that weak user, j ∈ { 1,2 }, strong user are expressed as ST3-j, it is contemplated that it uses
Fairness problem between family, is arranged Signal to Interference plus Noise Ratio threshold value τ, and Signal to Interference plus Noise Ratio threshold value τ is that letter required for user is correctly decoded is dry
It makes an uproar the minimum value of ratio, therefore, strong user ST3-jSignal to Interference plus Noise Ratio SINRHShown in the condition of satisfaction such as formula (VII):
In formula (VII), j is 1 or 2,1≤i≤m；
When the Signal to Interference plus Noise Ratio of strong user meets formula (VII), weak user obtains decoded chance, and the letter for seeking weak user is dry
It makes an uproar and compares SINRL, as shown in formula (VIII):
Final purpose of the invention is in two grade network, and the decoded premise of guarantee one energy increases access customer number, and
Enable its rate to reach maximum, therefore, seeks the achievable rate R of weak userL, as shown in formula (IX):
(3) combined optimization sends power, function molecular group and relay selection algorithm, and objective function is formula (IX), limits item
Part C1-C6 is as follows:
st.C1 I1+I2≤Ith
C3 SINRH≥τ
C4 0≤ρi≤1
C5 0≤P1≤P1max
C6 0≤P2≤P2max
IthThe jamming margin born by primary user PU under bottom access module；
C1 indicates that interference control is under jamming margin within stage first time；
C2 indicates that the second time phase relaying controls under jamming margin the interference of primary user；
C3 indicates the condition that the Signal to Interference plus Noise Ratio of strong user meets；
C4 indicates the value limitation of power splitting factor, realisation according to actual physics；
C5, C6 give the limitation that time user's transmitting terminal sends power,
It notices and works as ρiWhen fixed, noise power NiConstant will be become, the achievable rate of weak user is only with two users'
Send power P1And P2It is related, therefore, select to power splitting factor ρiIt is traversed, entire optimization problem is known as linear programming
Step delta ρ is arranged, respectively in ST in problem1With ST2It is calculated in the case where as weak user, chooses weak user's achievable rate most
One group of big solution is as optimal solution；
The selection of relaying and the selection of weak user are indicated as shown in formula (X), formula (XI):
In formula (X), formula (XI), by being traversed to each relaying, so that the achievable rate of weak user reaches maximum, i*
Indicate optimal relaying, j*Indicate time user ST1, ST2In the weak user WU that is more suitable for.
Embodiment 2
According to a kind of multi-user resource distribution based under NOMA and SWIPT cognitive radio environment described in embodiment 1
Method, difference are: in time first stage, two times user's transmitting terminal sends radiofrequency signal, relay reception radio frequency simultaneously
Signal simultaneously carries out energy harvesting；In the second stage time, relaying will execute remaining after energy gathers in time first stage
Signal is forwarded, and the energy for forwarding is provided by the energy being collected into stage first time；It comprises the following steps that
A, transmission process: stage first time: within stage first time, two user's transmitting terminal ST1And ST2Simultaneously
Signal is sent, R is relayediIt is activated and receives signal, 1≤i≤m, this will interfere PU during signal transmits.In order to prominent
The principal contradiction to go wrong, we will suitably simplify problem.Ignore the relaying R for executing collection of energyiEnergy consumption,
And assume that the distance between SR and PU are far, ignores in the interference caused by SR of PU communication period, as shown in formula (XII):
In formula (XII),Indicate the signal that relay reception is sent to time user, hI, 1It is time user's transmitting terminal ST1To relaying
RiSmall scale rayleigh fading channel, hI, 2It is time user's transmitting terminal ST2To relaying RiSmall scale rayleigh fading channel, dI, 1Table
Show relaying RiTo secondary user's transmitting terminal ST1Distance, dI, 2Indicate relaying RiTo secondary user's transmitting terminal ST2Distance, θ be path loss because
Son；aiIndicate PU to RiInterference, Gaussian distributed It is PU to RiJamming power, uiIndicate Gauss
White noise, x1, x2Respectively indicate ST1, ST2Transmitted power normalization signal, all channels are set as independent with the letter divided
Road gain is the Rayleigh stochastic variable of 0dB；
Relay RiAfter receiving signal, R is relayediPower segmentation is carried out, part signal is used for energy storage, and part signal is for turning
Hair；
B, the second time phase: relaying RiSignal is sent to secondary user receiving end SR, what secondary user receiving end SR was received
Shown in signal such as formula (XIII):
In formula (XIII), giIndicate relaying RiTo the channel gain of SR,Indicate relaying RiWith secondary user receiving end SR it
Between distance, c indicates the white Gaussian noise introduced when time user receiving end SR receives signal,
Power segmentation, refers to:
By power splitter, power allocation factor ρ is seti, ρi∈ [0,1], subscript i represent i-th of relaying, and signal is divided into
Two parts, the energy of energy storage, i.e. relaying RiThe ENERGY E being collected intoiAs shown in formula (XIV):
In formula (XIV), η indicates the energy conversion efficiency of RF energy collecting circuit, η ∈ [0,1]；The portion of energy will be by
For forward signal, R is relayediTransmission powerAs shown in formula (XV):
For the terseness of expression, so thatRelay RiIt connects
Get off to execute the link of amplification forwarding signal, signal amplification factor wi, as shown in formula (XVI):
In formula (XVI), biIndicate signal in relaying RiBy the frequency band white Gaussian noise introduced into base band conversion processes,Due to the very little compared with signal power to be forwarded, so being omitted in formula (4).Signal to be forwardedAnd noise biIt is all amplified in repeating process, therefore RiIn the signal such as formula of the second time phase forwarding
(XVII) shown in:
It is more under the cognitive radio environment based on the simultaneous interpretation of wireless messages energy and non-orthogonal multiple that the present embodiment is proposed
The system performance of user's relay communications system is as shown in Figure 2,3.By being compared with random relay selection, it is with 5 relayings
Example, Fig. 2's the results show that with primary user's jamming margin raising, the achievable rate of weak user can also correspondingly increase, but final
Limiting speed growth due to sending power tends towards stability.Fig. 3 then describes weak user's achievable rate in system and solves with strong user
The variation of code requirement, it is clear that decoding requirements needed for strong user are bigger, and the achievable rate of weak user is then smaller.Therefore, of the invention
Proposition increase the user of two grade network and access quantity, and introduce energy collection module, substantially increase system efficiency and
Frequency is imitated.
Claims (3)
1. a kind of multi-user resource distributing method based under NOMA and SWIPT cognitive radio environment, which is characterized in that operation
In based on multi-user's relay communications system under NOMA and SWIPT cognitive radio environment, including one primary user PU, m
After R1~Rm, two user's transmitting terminal ST1And ST2And one user receiving end SR, primary user PU are in communication always
State；The two isometric stages that are temporally divided into will be communicated between secondary user's transmitting terminal and relaying, in time first stage, two
Secondary user's transmitting terminal sends radiofrequency signal simultaneously, and relay reception radiofrequency signal simultaneously carries out energy harvesting；In the second stage time, in
Remaining signal is forwarded after having executed energy harvesting within by time first stage, when the energy for forwarding is by first
Between the energy that is collected into the stage provide；It comprises the following steps that
(1) interference of the two grade network work to primary user PU: two grade network includes two user's transmitting terminal ST1And ST2, in m
After R1~RmAnd one user receiving end SR, as two user's transmitting terminal ST1And ST2It sends in signal process, seeks
The interference I that primary user PU is subject in stage first time1, I2, respectively as shown in formula (I), formula (II):
In formula (I), formula (II), P1Indicate time user's transmitting terminal ST1Transmission power, P2Indicate time user's transmitting terminal ST2Transmission
Power, dU, 1Indicate primary user PU to time user's transmitting terminal ST1Distance, dU, 2Indicate primary user PU to time user's transmitting terminal ST2's
Distance, lU, 1Indicate primary user PU and time user's transmitting terminal ST1Between channel gain, lU, 2Indicate that primary user PU and time user are sent out
Sending end ST2Between channel gain, θ is path-loss factor；
Seek relaying RiI is interfered caused by primary user PU during forward signal3, as shown in formula (III):
In formula (III),It is primary user PU and relaying RiThe distance between, kiPrimary user PU is represented to relaying RiChannel
Gain；Indicate that transmission power when the second time phase relay forwarding signal, θ are path-loss factor；
(2) weak user ST in two grade network is calculatedjAchievable rate: high-power user's quilt is presented in j ∈ { 1,2 } at receiving end
Referred to as strong user SU, the user that low-power is presented at receiving end are referred to as weak user WU, and strong user is expressed as ST3-j；It acquires secondary
User receiving end SR respectively obtains time user's transmitting terminal ST1With ST2The power of useful signal, uses S respectively1, i, S2, iIt indicates, seeks
The noise power N of secondary user receiving end SRi, respectively as shown in formula (IV), formula (V), formula (VI):
Formula (IV), formula (V), in formula (VI), η, η ∈ [0,1], the energy conversion efficiency of indication circuit, ρi∈ [0,1], subscript i table
Show i-th of relaying, ρiIndicate power allocation factor when i-th of relaying executes energy harvesting, P1, P2Respectively indicate ST1And ST2's
Send power, hI, 1, hI, 2Respectively indicate ST1To Ri、ST2To RiSmall scale rayleigh fading channel channel gain, dI, 1, dI, 2
Respectively indicating indicates RiTo ST1、RiTo ST2Distance, θ be the path loss factor, giIndicate RiTo the channel gain of SR,It is RiWith
The distance between SR；The normalized power of the white Gaussian noise introduced when receiving signal for SR,It is PU to RiInterference function
Rate,For RiThe white Gaussian noise power introduced in receiving signal process,To relay RiFrom frequency band during forward signal
The white Gaussian noise power introduced to base band；
Be arranged Signal to Interference plus Noise Ratio threshold value τ, Signal to Interference plus Noise Ratio threshold value then user be correctly decoded required for Signal to Interference plus Noise Ratio minimum
Value, strong user ST3-jSignal to Interference plus Noise Ratio SINRHShown in the condition of satisfaction such as formula (VII):
In formula (VII), j is 1 or 2,1≤i≤m；
When the Signal to Interference plus Noise Ratio of strong user meets formula (VII), weak user obtains decoded chance, seeks the Signal to Interference plus Noise Ratio of weak user
SINRL, as shown in formula (VIII):
Seek the achievable rate R of weak userL, as shown in formula (IX):
(3) combined optimization sends power, function molecular group and relay selection algorithm, and objective function is formula (IX), restrictive condition C1-
C6 is as follows:
st.C1 I1+I2≤Ith
C3 SINRH≥τ
C4 0≤ρi≤1
C5 0≤P1≤P1max
C6 0≤P2≤P2max
IthThe jamming margin born by primary user PU under bottom access module；
C1 indicates that interference control is under jamming margin within stage first time；
C2 indicates that the second time phase relaying controls under jamming margin the interference of primary user；
C3 indicates the condition that the Signal to Interference plus Noise Ratio of strong user meets；
C4 indicates the value limitation of power splitting factor, realisation according to actual physics；
C5, C6 give the limit that time user's transmitting terminal sends power,
Selection is to power splitting factor ρiIt is traversed, entire optimization problem is known as linear programming problem, step delta ρ is arranged, respectively
In ST1With ST2It is calculated in the case where as weak user, chooses the maximum one group of solution of weak user's achievable rate as optimal solution；
The selection of relaying and the selection of weak user are indicated as shown in formula (X), formula (XI):
In formula (X), formula (XI), by being traversed to each relaying, so that the achievable rate of weak user reaches maximum, i*It indicates
Optimal relaying, j*Indicate time user ST1, ST2In the weak user WU that is more suitable for.
2. a kind of multi-user resource based under NOMA and SWIPT cognitive radio environment according to claim 1 distributes
Method, which is characterized in that in time first stage, two times user's transmitting terminal sends radiofrequency signal, relay reception radio frequency simultaneously
Signal simultaneously carries out energy harvesting；In the second stage time, relaying will execute remaining after energy gathers in time first stage
Signal is forwarded, and the energy for forwarding is provided by the energy being collected into stage first time；It comprises the following steps that
A, transmission process: stage first time: within stage first time, two user's transmitting terminal ST1And ST2It sends simultaneously
Signal relays RiIt is activated and receives signal, 1≤i≤m ignores the relaying R for executing collection of energyiEnergy consumption, and
And assume that the distance between SR and PU are far, ignore in the interference caused by SR of PU communication period, as shown in formula (XII):
In formula (XII),Indicate the signal that relay reception is sent to time user, hI, 1It is time user's transmitting terminal ST1To relaying Ri's
Small scale rayleigh fading channel, hI, 2It is time user's transmitting terminal ST2To relaying RiSmall scale rayleigh fading channel, dI, 1In expression
After RiTo secondary user's transmitting terminal ST1Distance, dI, 2Indicate relaying RiTo secondary user's transmitting terminal ST2Distance, θ be the path loss factor；ai
Indicate PU to RiInterference, Gaussian distributedIt is PU to RiJamming power, uiIndicate white Gaussian
Noise, x1, x2Respectively indicate ST1, ST2Transmitted power normalization signal, all channels are set as independent with the channel divided
Gain is the Rayleigh stochastic variable of 0dB:
Relay RiAfter receiving signal, R is relayediPower segmentation is carried out, part signal is used for energy storage, and part signal is for forwarding；
B, the second time phase: relaying RiSignal is sent to secondary user receiving end SR, the signal that secondary user receiving end SR is received is such as
Shown in formula (XIII):
In formula (XIII), giIndicate relaying RiTo the channel gain of SR,Indicate relaying RiBetween secondary user receiving end SR
Distance, c indicate the white Gaussian noise introduced when time user receiving end SR receives signal,
3. a kind of multi-user resource based under NOMA and SWIPT cognitive radio environment according to claim 2 distributes
Method, which is characterized in that power segmentation refers to:
By power splitter, power allocation factor ρ is seti, ρi∈ [0,1], subscript i represent i-th of relaying, and signal is divided into two
Point, the energy of energy storage, i.e. relaying RiThe ENERGY E being collected intoiAs shown in formula (XIV):
In formula (XIV), η indicates the energy conversion efficiency of RF energy collecting circuit, η ∈ [0,1]；The portion of energy will be used for
Forward signal relays RiTransmission powerAs shown in formula (XV):
So thatRelay RiNext amplification forwarding signal is executed
Link, signal amplification factor wi, as shown in formula (XVI):
In formula (XVI), biIndicate signal in relaying RiBy the frequency band white Gaussian noise introduced into base band conversion processes,RiShown in the signal such as formula (XVII) of the second time phase forwarding:
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| CN111371476A (en) * | 2020-03-17 | 2020-07-03 | 中国计量大学 | Wireless energy acquisition cooperation system based on multiple access |
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