CN112737657B - Optimal relay node selection and power distribution method under cooperative diversity system - Google Patents

Optimal relay node selection and power distribution method under cooperative diversity system Download PDF

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CN112737657B
CN112737657B CN202011601004.7A CN202011601004A CN112737657B CN 112737657 B CN112737657 B CN 112737657B CN 202011601004 A CN202011601004 A CN 202011601004A CN 112737657 B CN112737657 B CN 112737657B
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relay node
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CN112737657A (en
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包建荣
亓凯梁
刘超
姜斌
吴俊�
唐向宏
邱雨
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Hangzhou Dianzi University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/005—Control of transmission; Equalising
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W72/00—Local resource management
    • H04W72/04—Wireless resource allocation
    • H04W72/044—Wireless resource allocation based on the type of the allocated resource
    • H04W72/0473—Wireless resource allocation based on the type of the allocated resource the resource being transmission power
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • 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

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Abstract

The invention belongs to the field of digital communication, and particularly relates to an optimal relay node selection and power distribution method under a cooperative diversity system, which is mainly completed by the following steps of S1: a source node transmits a signal; s2: taking the modulated signal obtained in the step S12 as an input parameter, and performing calculation according to a candidate relay node set construction method to obtain a candidate relay node set with good channel quality from the source node to the relay node; s3: taking the alternative relay node set obtained in the step S2 as an input parameter, and performing calculation according to a cooperation judgment method to obtain a relay node set suitable for cooperation; s4: taking the relay node set suitable for cooperation obtained in the step S3 as an input parameter, and executing calculation according to an optimal relay node selection and power distribution method to obtain an optimal relay node which enables the channel capacity from a source node to a destination node to be maximum; s5: the destination node receives the signal. The invention reduces the system interruption probability and improves the energy utilization rate of the system.

Description

Optimal relay node selection and power distribution method under cooperative diversity system
Technical Field
The invention belongs to the field of digital communication, and particularly relates to an optimal relay node selection and power distribution method in a cooperative diversity system.
Background
In recent years, in the field of wireless communication, obtaining performance gain by diversity in a Multiple Input Multiple Output (MIMO) system has been receiving extensive attention and research in the industry. And cooperative communication is to allow users in the system to complete cooperation by relaying messages between each other to a destination. This effectively forms a distributed antenna array to achieve the spatial diversity gain achieved by a centralized MIMO system. The common relay method for cooperative communication includes: amplify-and-forward (AF), decode-and-forward (DF), Selective Relay (SR), Coding Cooperation (CC), and compress-and-forward (CF), among others. The Laneman J N et al analyzes a distributed space-time coding method in cooperation, reduces loss of frequency spectrum efficiency, and the Bletsas A et al provides an optimal relay method in a multi-relay system, selects a relay node with optimal performance from a plurality of relay nodes for forwarding, and proves that the performance is superior to that of distributed space-time coding under the condition of equal power. However, the prior art still has the defects that the system has low energy utilization rate under the condition of limited total power and the system is easy to interrupt.
The invention provides an optimal relay node selection and power distribution method under a cooperative diversity system based on a polarization code coding and decoding method, a modulation method and a Maximum Ratio Combining (MRC) method in the prior art. Wherein the content of the first and second substances,
1. polarization code coding and decoding method
An information sequence with length bit K is constructed into an information code word vector u with the length of 1 multiplied by L through a channel polarization theory (u is equal to1,u2,…,uL). Wherein K and L are natural numbers and have K<And L. The u element contains K information bits and L-K frozen bits, which do not convey information and can all be represented by codeword 0. Then, a polar code P (L, K) with a code length L and an information bit length K is coded into a codeword x by a polar coding method, and the codeword x can be decoded by a successive erasure coding (SC) method. The Channel Polarization Theory, Polarization coding and continuous deletion decoding Method are concretely described in 'E.Arikan, Channel Polarization: A Method for transforming Capacity-Achieveying Codes for symmetry Binary-Input memory Channels, IEEE Transactions on Information Theory, vol.55, No.7, pp.3051-3073, July 2009'.
2. Modulation method
The source node polarization channel coding obtains a code word x ═ (x)1,x2,…,xL) Modulation is accomplished through variations in amplitude, frequency, phase, etc. See specifically "H · morkar, jing, a · Y · golhoff, et al. Such as Binary Phase Shift Keying (BPSK) modulation, is achieved by: si＝1-2xiI is a natural number ranging from 1 to L, L represents a codeword length, siIs xiCorresponding BPSK modulation symbols, siE { -1,1 }. Other modulation methods are similar, see the above references.
3. Maximal Ratio Combining (MRC) method
To fully exploit the spatial diversity gain provided by multipath reception, MRC selects a weighting factor that maximizes the received SNR, thereby reducing outage probability. See in particular "D G Brennan, On the maximum signal-to-noise ratio conversion from partial noise signals, Proc IRE, vol 43, p1530, Oct 1955". In particular, the weight factor for MRC, given instantaneous channel state information, is given by:
Figure BDA0002869346520000021
wherein, i is a natural number,
Figure BDA0002869346520000022
for the link channel coefficient hiConjugation of (1).
Disclosure of Invention
Based on the defects that the system energy utilization rate is not high and the system is easy to interrupt under the condition that the total power is limited in the prior art, the invention provides an optimal relay node selection and power distribution method under a cooperative diversity system, and the system performance is improved by combining a channel polarization coding and selection decoding forwarding mode; the relay node which enables the channel capacity from the source node to the destination node to be maximum is selected for forwarding, and the system interruption probability is reduced.
The invention adopts the following technical scheme:
a method for selecting optimal relay nodes and distributing power under a cooperative diversity system is characterized by comprising the following steps,
s1: the source node transmits a signal, comprising the steps of,
s11: the source node performs channel polarization coding on an original signal to be transmitted, namely binary bit data;
s12 executing amplitude or phase modulation method to the code word obtained from S11 to obtain modulation signal, then broadcasting to all relay and destination nodes through transmitting antenna;
s2: taking the modulated signal obtained in the step S12 as an input parameter, and performing calculation according to a candidate relay node set construction method to obtain a candidate relay node set with good channel quality from the source node to the relay node;
s3: taking the alternative relay node set obtained in the step S2 as an input parameter, and performing calculation according to a cooperation judgment method to obtain a relay node set suitable for cooperation;
s4: taking the relay node set suitable for cooperation obtained in the step S3 as an input parameter, and executing calculation according to an optimal relay node selection and power distribution method to obtain an optimal relay node which enables the channel capacity from a source node to a destination node to be maximum;
s5: the destination node receives the signal.
Preferably, in step S2, the method for constructing an alternative relay node set includes the following steps:
step S21: in the multi-relay cooperative system, the system comprises a source node S, a destination node D and a plurality of relay nodes RiAnd i ranges from 1 to M. Where M represents the number of all relay nodes. The source node broadcasts the signal to the relay and the destination node, the destination node D and the ith (i is more than or equal to 1 and less than or equal to M) relay node RiThe received signals are respectively:
Figure BDA0002869346520000031
Figure BDA0002869346520000032
wherein x issIs a real number, representing a modulated signal; psIs a real number and represents the transmitting power of the source node S; h issdAnd
Figure BDA0002869346520000036
is zero mean and the variance is respectively
Figure BDA0002869346520000033
And
Figure BDA0002869346520000034
and mutually independent complex Gaussian random variables representing S-D and S-RiChannel coefficients of the link. Wherein eta issdAnd ηsriIs a real number, representing S-D and S-R, respectivelyiStandard deviation of the link channel coefficients. And n issdAnd
Figure BDA0002869346520000037
is zero mean and variance is real
Figure BDA0002869346520000035
And mutually independent complex Gaussian random variables respectively representing S-D and S-RiAdditive white gaussian noise of the link. Wherein σnIs a real number and represents the standard deviation of additive white gaussian noise.
Step S22: in order to obtain a relay node set with better channel quality from a source node to a relay node, a threshold theta (can be 1) is set, when S-R is usediAnd when the square of the channel coefficient mode of the link is greater than a threshold value, selecting the relay node into an alternative relay node set omega.
Figure BDA0002869346520000041
Preferably, the method for determining cooperation in step S3 includes the following steps:
step S31: adopting the alternative relay node set selected in the step 2.2, if the alternative relay node set Ω is empty, that is, the channel quality from the source node to the relay node does not meet the requirement, the system does not depend on the relay node, adopts the link to transmit directly, and all the power of the system is used for direct transmission:
Figure BDA0002869346520000042
wherein the content of the first and second substances,
Figure BDA0002869346520000043
for plural, representationSignals, P, received by destination node D in the case of link-direct transmissionTotalAnd is a real number representing the total power transmitted by the system.
Since no relay node participates, the channel capacity of the link direct transmission can be expressed as
Figure BDA0002869346520000044
Wherein, IDTAnd the real number represents the channel capacity of the link direct transmission.
Step S32: if the candidate relay node set omega is not empty, for any relay node R in omegaiFor the relay node to correctly decode and forward the source node signal, S-R needs to be satisfiediThe channel capacity of the link being greater than the transmission rate V of the system, i.e.
Figure BDA0002869346520000045
In order to ensure the source node transmitting power of the relay node for correct decoding, the following relationship is also required
Figure BDA0002869346520000046
Wherein the content of the first and second substances,
Figure BDA0002869346520000048
and the real number represents the transmission power of the source node when the ith relay node can successfully decode. For the situation that the total power of the system is limited, if the total power of the system is: p isTotalLess than the satisfaction of the relay node RiThe minimum power required to be correctly decoded:
Figure BDA0002869346520000047
the ith relay node does not participate in the cooperation, i is a natural number and ranges from 1 to | Ω |, and | Ω | is the number of elements in the candidate relay set Ω.
Step S33: respectively meterCalculate Ri-squaring of channel coefficient patterns of the D-link and S-D link, if
Figure BDA0002869346520000051
This indicates the ith relay node RiAnd the channel quality of the D link is worse than that of the S-D link, and the ith relay node does not participate in the cooperation. Wherein the content of the first and second substances,
Figure BDA0002869346520000052
is zero mean and variance of
Figure BDA0002869346520000053
Is a complex Gaussian random variable representing Ri-the channel coefficients of the D-link,
Figure BDA0002869346520000054
is a real number, represents Ri-standard deviation of D link channel coefficients.
As a preferred scheme, the optimal relay node selecting and power allocating method in step S4 includes the following steps:
step S41: for total system power PTotalGreater than and equal to relay node RiMinimum power required for correct decoding
Figure BDA0002869346520000055
And is
Figure BDA0002869346520000056
In the case of a relay node RiCan be correctly decoded and RiUnder the condition that the channel quality of the D link is stronger than that of the S-D link, in order to maximize the signal-to-noise ratio of the destination node, the relay node R is required to beiTransmitting with as much power as possible. Therefore, the ith relay node RiThe transmission power of (a) is:
Figure BDA0002869346520000057
then the channel capacity from the source node to the destination node at this time can be expressed as:
Figure BDA0002869346520000058
step S42: comparing channel capacity I from source node to destination node of link direct transmissionDTAnd selecting the ith relay node RiChannel capacity I from time source node to destination nodeiThe size of (2).
Because the outage probability of the system is Pr (I < V), wherein I represents the channel capacity from the source node to the destination node, and Pr (.) is a real variable and represents a probability value. The choice of maximizing the channel capacity from the source node to the destination node reduces the outage probability of the system.
The node with the largest channel capacity is then selected for decoding forwarding or direct forwarding.
Imax＝max(IDT,Ii,i＝1～|Ω|) (11)
Wherein, ImaxFor the selected maximum channel capacity, if Imax＝IDTIf the channel capacity of the link direct transmission is the maximum, the step S31 is skipped to, the direct transmission link S-D transmission is preferentially selected, and the relay node does not participate in the cooperative transmission; if Imax＝IiAnd i is 1 to omega, the selected ith relay node RiAfter the received signal is processed by the polar code continuous deleting decoding method described in the background technology, the channel polar code described in the background technology is executed again and forwarded to the destination node D. At RiThe signal forwarded by coding can be represented as
Figure BDA0002869346520000061
D the received signal
Figure BDA0002869346520000062
Can be expressed as
Figure BDA0002869346520000063
Wherein the content of the first and second substances,
Figure BDA0002869346520000064
is zero mean and variance is real
Figure BDA0002869346520000065
Is independent of each other, represents Ri-additive white gaussian noise for the D-link.
Preferably, in step S5, the step of receiving the signal by the destination node is: after receiving the signals of the two stages described in step S21 and step S42 or the signals directly forwarded by the link described in step S31 and step S41, the destination node performs a maximum ratio combining method to combine all the received signals, and then performs demodulation and decoding by a continuous erasure decoding method in sequence to obtain a signal sequence estimated by the destination node, which is the final result.
Compared with the prior art, the invention has the beneficial effects that:
the invention combines the channel polarization coding and decoding forwarding method, and realizes the optimal relay node selection and power distribution method scheme under a cooperative diversity system; aiming at the problem of low energy utilization rate of the system under the condition that the total power of the system is limited at present, a power distribution scheme between a source node and a selected relay node is provided; the relay node which enables the channel capacity from the source node to the destination node to be maximum is selected for forwarding, and the system interruption probability is reduced; and the system performance is improved by combining advanced channel polarization coding and selective decoding forwarding.
Drawings
Fig. 1 is a flowchart of an optimal relay node selection and power allocation method in a cooperative diversity system according to an embodiment of the present invention;
FIG. 2 is a flowchart illustrating a step of a source node transmitting a signal according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for constructing an alternative relay node set according to an embodiment of the present invention;
FIG. 4 is a flowchart of a method for determining collaboration in accordance with an embodiment of the present invention;
fig. 5 is a flowchart of an optimal relay node selection and power distribution method according to an embodiment of the present invention;
FIG. 6 is a flowchart illustrating a signal receiving procedure of a destination node according to an embodiment of the present invention;
Detailed Description
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.
The embodiment of the invention provides an optimal relay node selection and power distribution method in a cooperative diversity system, which comprises the following steps:
s1: the source node transmits a signal.
The method for transmitting the signal by the source node comprises the following steps:
s11: the source node performs channel polarization coding on the original signal to be transmitted as described in the background.
S12: the coded code word obtained in step S11 is subjected to the modulation method described in the background art, and then broadcast to all relays and destination nodes via the transmitting antenna.
S2: and taking the modulated signal obtained in the step S12 as an input parameter, and performing calculation according to a candidate relay node set construction method to obtain a candidate relay node set with good channel quality from the source node to the relay node.
The method for constructing the alternative relay node set comprises the following steps:
s21: in the multi-relay cooperative system, the system comprises a source node S, a destination node D and a plurality of relay nodes RiAnd i ranges from 1 to M. Where M represents the number of all relay nodes. The source node broadcasts the signal to the relay and the destination node, the destination node D and the ith (i is more than or equal to 1 and less than or equal to M) relay node RiThe received signals are respectively:
Figure BDA0002869346520000071
Figure BDA0002869346520000072
wherein x issFor real numbers, the tone obtained in step 1.2 is shownA processed signal; psIs a real number and represents the transmitting power of the source node S; h issdAnd
Figure BDA0002869346520000078
is zero mean and the variance is respectively
Figure BDA0002869346520000073
And
Figure BDA0002869346520000074
and mutually independent complex Gaussian random variables representing S-D and S-RiChannel coefficients of the link. Wherein eta issdAnd
Figure BDA0002869346520000075
is a real number, representing S-D and S-R, respectivelyiStandard deviation of the link channel coefficients. And n issdAnd
Figure BDA0002869346520000076
is zero mean and variance is real
Figure BDA0002869346520000077
And mutually independent complex Gaussian random variables respectively representing S-D and S-RiAdditive white gaussian noise of the link. Wherein σnIs a real number and represents the standard deviation of additive white gaussian noise.
S22: in order to obtain a relay node set with better channel quality from a source node to a relay node, a threshold theta (can be 1) is set, when S-R is usediAnd when the square of the channel coefficient mode of the link is larger than a threshold value, selecting the relay node into an alternative relay node set omega.
Figure BDA0002869346520000081
S3: and taking the alternative relay node set obtained in the step S2 as an input parameter, and performing calculation according to a cooperation judgment method to obtain a relay node set suitable for cooperation.
The cooperative judgment method is completed by adopting the following steps:
s31: adopting the alternative relay node set selected in step S22, if the alternative relay node set Ω is empty, that is, the channel quality from the source node to the relay node does not meet the requirement, the system does not rely on the relay node, adopts the link to transmit directly, and all the power of the system is used for direct transmission:
Figure BDA0002869346520000082
wherein the content of the first and second substances,
Figure BDA0002869346520000083
is a complex number representing the signal received by the destination node D in the case of direct transmission using a link, PTotalAnd is a real number representing the total power transmitted by the system.
Since no relay node participates, the channel capacity of the link direct transmission can be expressed as
Figure BDA0002869346520000084
Wherein, IDTAnd the real number represents the channel capacity of the link direct transmission.
S32: if the candidate relay node set omega is not empty, for any relay node R in omegaiFor the relay node to correctly decode and forward the source node signal, S-R needs to be satisfiediThe channel capacity of the link being greater than the transmission rate V of the system, i.e.
Figure BDA0002869346520000085
In order to ensure the source node transmitting power of the relay node for correct decoding, the following relationship is also required
Figure BDA0002869346520000086
Wherein the content of the first and second substances,
Figure BDA0002869346520000087
and the real number represents the transmission power of the source node when the ith relay node can successfully decode. For the case of the total power limit of the system, if the total power of the system is: pTotalLess than satisfactory relay node RiThe minimum power required to be correctly decoded:
Figure BDA0002869346520000088
the ith relay node does not participate in the cooperation, i is a natural number and ranges from 1 to | Ω |, and | Ω | is the number of elements in the candidate relay set Ω.
S33: respectively calculate RiSquaring of channel coefficient patterns for D-link and S-D link, if
Figure BDA0002869346520000091
This indicates the ith relay node RiAnd the channel quality of the D link is worse than that of the S-D link, and the ith relay node does not participate in the cooperation. Wherein the content of the first and second substances,
Figure BDA0002869346520000092
is zero mean and variance of
Figure BDA0002869346520000093
Is a complex Gaussian random variable representing Ri-the channel coefficients of the D-link,
Figure BDA0002869346520000094
is a real number, represents Ri-standard deviation of D link channel coefficients.
S4: and taking the relay node set suitable for cooperation obtained in the step S3 as an input parameter, and executing calculation according to an optimal relay node selection and power distribution method to obtain an optimal relay node which enables the channel capacity from the source node to the destination node to be maximum.
The optimal relay node selection and power distribution method is completed by adopting the following steps:
s41: for total work of systemRate PTotalGreater than and equal to relay node RiMinimum power required for correct decoding
Figure BDA0002869346520000095
And is provided with
Figure BDA0002869346520000096
In the case of a relay node RiCan be correctly decoded and RiUnder the condition that the channel quality of the D link is stronger than that of the S-D link, in order to maximize the signal-to-noise ratio of the destination node, the relay node R is required to beiTransmitting with as much power as possible. So the ith relay node RiWith a transmission power of
Figure BDA0002869346520000097
The channel capacity from the source node to the destination node at this time can be expressed as
Figure BDA0002869346520000098
S42: comparing channel capacity I from source node to destination node of link direct transmissionDTAnd selecting the ith relay node RiChannel capacity I from time source node to destination nodeiThe size of (2).
Because the outage probability of the system is Pr (I < V), where I represents the channel capacity from the source node to the destination node, and Pr (.) is a real number, representing a probability value. The choice of maximizing the channel capacity from the source node to the destination node reduces the outage probability of the system.
The node with the largest channel capacity is then selected for decoding forwarding or direct forwarding.
Imax＝max(IDT,Ii,i＝1～|Ω|) (22)
Wherein, ImaxFor the selected maximum channel capacity, if Imax＝IDTIf the channel capacity of the link direct transmission is the maximum, the process goes to step S31 to select the direct transmission preferentiallyLink S-D transmission, wherein the relay node does not participate in cooperative transmission; if Imax＝IiAnd i is 1 to omega, the selected ith relay node RiAfter the received signal is processed by the polar code continuous deleting decoding method described in the background technology, the channel polar code described in the background technology is executed again and forwarded to the destination node D. At RiThe signal forwarded by coding can be represented as
Figure BDA0002869346520000101
Then D received signal
Figure BDA0002869346520000102
Can be expressed as
Figure BDA0002869346520000103
Wherein the content of the first and second substances,
Figure BDA0002869346520000104
is zero mean and variance is real
Figure BDA0002869346520000105
Is a complex Gaussian random variable representing Ri-additive white gaussian noise for the D-link.
S5: the destination node receives the signal, comprising the steps of,
s51: after receiving the two-stage signals of step S21 and step S42 or the signals directly forwarded by link only of step S31 and step S41, the maximum ratio combining method reception described in the background is performed.
S52: the demodulation and polar code decoding methods described in the background art are sequentially performed on the received signal obtained in S51 to obtain an estimated signal, i.e., the final result of the method.
As shown in fig. 1, a method for selecting an optimal relay node and allocating power in a cooperative diversity system according to an embodiment of the present invention is mainly completed through the following steps: step one, a source node transmits signals: the source node sequentially executes channel polarization coding and modulation on an original signal to be transmitted, and broadcasts the original signal to all relay and target nodes through a transmitting antenna; step two, a method for constructing an alternative relay node set: selecting a relay node with better channel quality from a source node to the relay node as a standby relay node set; step three, the cooperation judging method comprises the following steps: judging whether a relay node participates in cooperation or not according to the condition that the total power of a system is limited and the channel state information; step four, the optimal relay node selection and power distribution method comprises the following steps: selecting a relay with the largest channel capacity from a source node to a destination node as an optimal relay node, and distributing power between the selected relay node and the source node; step five, the step of receiving signals by the destination node: after the signal reaches the destination node, the maximum ratio combining method is adopted for receiving, and then the signal is demodulated and polarized decoded to obtain an estimated original signal.
Fig. 2 is a flow chart of the steps of transmitting a signal by a source node. The source node performs channel polarization coding on the signal sequence to be transmitted, as described in the background. The coded codeword is then subjected to the modulation method described in the background art and broadcast in free space to all relay and destination nodes via the transmit antennas.
Fig. 3 is a flowchart of an alternative relay node set construction method. In the multi-relay cooperative system, a source node S, a destination node D and a plurality of relay nodes R are includediAnd i ranges from 1 to M. Where M represents the number of all relay nodes. The source node broadcasts the signal to the relay and the destination node, the destination node D and the ith (i is more than or equal to 1 and less than or equal to M) relay node RiThe received signals are respectively:
Figure BDA0002869346520000111
Figure BDA0002869346520000112
wherein x issIs a real number, representing a modulated signal; psIs a real number, representing the work of transmission of the source node SRate; h issdAnd
Figure BDA0002869346520000113
is zero mean and the variance is respectively
Figure BDA0002869346520000114
And
Figure BDA0002869346520000115
and mutually independent complex Gaussian random variables representing S-D and S-RiChannel coefficients of the link. Wherein etasdAnd
Figure BDA0002869346520000116
is a real number, representing S-D and S-R, respectivelyiStandard deviation of the link channel coefficients. And n issdAnd
Figure BDA0002869346520000117
is zero mean and variance is real
Figure BDA0002869346520000118
And mutually independent complex Gaussian random variables respectively representing S-D and S-RiAdditive white gaussian noise of the link. Wherein σnIs a real number representing the standard deviation of additive white gaussian noise.
In order to obtain a relay node set with better channel quality from a source node to a relay node, a threshold theta (can be 1) is set, when S-R is usediAnd when the square of the channel coefficient mode of the link is larger than a threshold value, selecting the relay node into an alternative relay node set omega.
Figure BDA0002869346520000119
Fig. 4 is a flowchart of a cooperation deciding method. Adopting an alternative relay node set, if the alternative relay node set omega is empty, namely the channel quality from a source node to a relay node does not meet the requirement, the system does not depend on the relay node, adopting a link for direct transmission, and using all power of the system for direct transmission:
Figure BDA00028693465200001110
wherein the content of the first and second substances,
Figure BDA00028693465200001111
is a complex number representing the signal received by the destination node D in the case of direct transmission using a link, PTotalAnd is a real number representing the total power transmitted by the system.
Since no relay node participates, the channel capacity of the link direct transmission can be expressed as
Figure BDA00028693465200001112
Wherein, IDTAnd is a real number, which represents the channel capacity of the link direct transmission.
If the candidate relay node set omega is not empty, for any relay node R in omegaiFor the relay node to correctly decode and forward the source node signal, S-R needs to be satisfiediThe channel capacity of the link being greater than the transmission rate V of the system, i.e.
Figure BDA0002869346520000121
In order to ensure the source node transmitting power of the relay node for correct decoding, the following relationship is also required
Figure BDA0002869346520000122
Wherein, PSiAnd the real number represents the transmission power of the source node when the ith relay node can successfully decode. For the situation that the total power of the system is limited, if the total power of the system is: pTotalLess than satisfactory relay node RiThe minimum power required to be correctly decoded:
Figure BDA0002869346520000123
the ith relay node does not participate in the cooperation, i is a natural number and ranges from 1 to | Ω |, and | Ω | is the number of elements in the candidate relay set Ω.
Respectively calculate Ri-squaring of channel coefficient patterns of the D-link and S-D link, if
Figure BDA0002869346520000124
This indicates the ith relay node RiAnd the channel quality of the D link is worse than that of the S-D link, and the ith relay node does not participate in the cooperation. Wherein the content of the first and second substances,
Figure BDA0002869346520000125
is zero mean and variance of
Figure BDA0002869346520000126
Is a complex Gaussian random variable representing Ri-the channel coefficients of the D-link,
Figure BDA0002869346520000127
is a real number, represents Ri-standard deviation of D link channel coefficients.
Fig. 5 is a flowchart of an optimal relay node selection and power allocation method. For total power P of systemTotalGreater than and equal to relay node RiMinimum power required for correct decoding
Figure BDA0002869346520000128
And is
Figure BDA0002869346520000129
In the case of a relay node RiCan be correctly decoded and RiUnder the condition that the channel quality of the D link is stronger than that of the S-D link, in order to maximize the signal-to-noise ratio of the destination node, the relay node R is required to beiTransmitting with as much power as possible. So the ith relay node RiWith a transmission power of
Figure BDA00028693465200001210
The channel capacity from the source node to the destination node at this time can be expressed as
Figure BDA00028693465200001211
Comparing channel capacity I from source node to destination node of link direct transmissionDTAnd selecting the ith relay node RiChannel capacity I from time source node to destination nodeiThe size of (2).
Because the outage probability of the system is Pr (I < V), where I represents the channel capacity from the source node to the destination node, and Pr (.) is a real number, representing a probability value. The choice of maximizing the channel capacity from the source node to the destination node reduces the outage probability of the system.
The node with the largest channel capacity is then selected for decoding forwarding or direct forwarding.
Imax＝max(IDT,Ii,i＝1～|Ω|) (33)
Wherein, ImaxFor the selected maximum channel capacity, if Imax＝IDTIf the channel capacity of the link direct transmission is the maximum, the step S31 is skipped to, the direct transmission link S-D transmission is preferentially selected, and the relay node does not participate in the cooperative transmission; if Imax＝IiAnd i is 1 to omega, the selected ith relay node RiAfter the received signal is processed by the polar code continuous deleting decoding method described in the background art, the channel polar code described in the background art is executed again and is forwarded to the destination node D. At RiThe signal forwarded by coding can be represented as
Figure BDA0002869346520000131
Then D received signal
Figure BDA0002869346520000132
Can be expressed as
Figure BDA0002869346520000133
Wherein the content of the first and second substances,
Figure BDA0002869346520000134
is zero mean and variance is real
Figure BDA0002869346520000135
Is a complex Gaussian random variable representing Ri-additive white gaussian noise for the D-link.
Fig. 6 is a flow chart of the steps of the destination node receiving a signal. For the signal transmitted to the destination node, the maximum ratio combining method described in the background art is performed to combine all the received signals. Then, the combined signal sequence is sequentially subjected to demodulation and polarization code decoding methods described in the background art to obtain a signal estimated by a target node, namely the final result of the method.
While the embodiments of the present invention have been described in detail, it will be apparent to those skilled in the art that variations may be made in the embodiments without departing from the spirit of the invention, and such variations are to be considered within the scope of the invention.

Claims (2)

1. A method for selecting optimal relay nodes and distributing power under a cooperative diversity system is characterized by comprising the following steps,
s1: the source node transmits a signal, comprising the steps of,
s11: the source node performs channel polarization coding on an original signal to be transmitted, namely binary bit data;
s12: executing an amplitude or phase modulation method on the coded code word obtained in the step S11 to obtain a modulation signal, and broadcasting the modulation signal to all relays and target nodes through a transmitting antenna;
s2: taking the modulated signal obtained in the step S12 as an input parameter, and performing calculation according to a candidate relay node set construction method to obtain a candidate relay node set with good channel quality from the source node to the relay node;
s3: taking the alternative relay node set obtained in the step S2 as an input parameter, and performing calculation according to a cooperation judgment method to obtain a relay node set suitable for cooperation;
s4: taking the relay node set suitable for cooperation obtained in the step S3 as an input parameter, and executing calculation according to an optimal relay node selection and power distribution method to obtain an optimal relay node which enables the channel capacity from a source node to a destination node to be maximum;
s5: a destination node receives a signal;
in step S2, the method for constructing an alternative relay node set includes the following steps:
s21: in the multi-relay cooperative system, the system comprises a source node S, a destination node D and a plurality of relay nodes RiI ranges from 1 to M; wherein M represents the number of all relay nodes; the source node broadcasts the signal to the relay and destination nodes, the destination node D and the ith relay node RiThe received signals are respectively:
Figure FDA0003578146610000011
Figure FDA0003578146610000012
wherein i is more than or equal to 1 and less than or equal to M, xsA real number, representing the modulated signal obtained in step S12; psIs a real number and represents the transmitting power of the source node S; h is a total ofsdAnd
Figure FDA0003578146610000013
is zero mean and the variance is respectively
Figure FDA0003578146610000014
And
Figure FDA0003578146610000015
and mutually independent complex Gaussian random variables respectively representing S-D and S-RiLink circuitThe channel coefficient of (a); wherein eta issdAnd
Figure FDA0003578146610000016
is a real number, representing S-D and S-R, respectivelyiStandard deviation of link channel coefficients; and n issdAnd
Figure FDA0003578146610000021
is zero mean and variance is real
Figure FDA0003578146610000022
And mutually independent complex Gaussian random variables respectively representing S-D and S-RiAdditive white gaussian noise of the link; wherein σnIs a real number, representing the standard deviation of additive white gaussian noise;
s22: setting a threshold theta when S-RiWhen the square of the channel coefficient mode of the link is larger than a threshold value, the relay node is selected into an alternative relay node set omega
Figure FDA0003578146610000023
In step S3, the cooperation determination method is completed by the following steps:
s31: adopting the alternative relay node set selected in step S22, if the alternative relay node set Ω is empty, that is, the channel quality from the source node to the relay node does not meet the requirement, the system does not rely on the relay node, adopts the link to transmit directly, and all the power of the system is used for direct transmission:
Figure FDA0003578146610000024
wherein the content of the first and second substances,
Figure FDA0003578146610000025
is a complex number representing the signal received by the destination node D in the case of direct transmission using a link, PTotalReal number, representing the total power emitted by the system;
since no relay node participates, the channel capacity of the link direct transmission is expressed as
Figure FDA0003578146610000026
Wherein, IDTThe real number represents the channel capacity of the link direct transmission;
s32: if the candidate relay node set omega is not empty, for any relay node R in omegaiFor the relay node to correctly decode and forward the source node signal, S-R needs to be satisfiediThe channel capacity of the link being greater than the transmission rate V of the system, i.e.
Figure FDA0003578146610000027
In order to ensure the source node transmitting power of the relay node for correct decoding, the following relationship is also required
Figure FDA0003578146610000028
Wherein the content of the first and second substances,
Figure FDA0003578146610000029
the real number represents the transmitting power of the source node when the ith relay node can successfully decode; for the limited total system power, if the total system power PTotalLess than satisfactory relay node RiMinimum power required for correct decoding
Figure FDA00035781466100000210
The ith relay node does not participate in cooperation, i is a natural number and ranges from 1 to | omega |, and | omega | is the number of elements in the candidate relay node set omega;
s33: respectively calculate RiSquaring of channel coefficient patterns for D-link and S-D link, if
Figure FDA0003578146610000031
It indicates the ith relay node RiThe channel quality of the D link is worse than that of the S-D link, and the ith relay node does not participate in cooperation; wherein the content of the first and second substances,
Figure FDA0003578146610000032
is zero mean and variance of
Figure FDA0003578146610000033
Is a complex Gaussian random variable representing Ri-the channel coefficients of the D-link,
Figure FDA0003578146610000034
is a real number, representing Ri-D standard deviation of link channel coefficients;
in step S4, the optimal relay node selection and power allocation method is completed by the following steps:
s41: for total system power PTotalGreater than and equal to relay node RiMinimum power required for correct decoding
Figure FDA0003578146610000035
And is provided with
Figure FDA0003578146610000036
In the case of a relay node RiCan be correctly decoded and Ri-the channel quality of the D-link is stronger than the channel quality of the S-D link;
ith relay node RiIs transmitted at a power of
Figure FDA0003578146610000037
The channel capacity from the source node to the destination node at this time is expressed as
Figure FDA0003578146610000038
S42: comparing the channel capacity I from the source node to the destination node of the link direct transmissionDTAnd selecting the ith relay node RiChannel capacity I from time source node to destination nodeiThe size of (d);
the interrupt probability of the system is Pr (I < V), wherein I represents the channel capacity from the source node to the destination node, and Pr (.) is a real number and represents a probability value; selecting the channel capacity from the source node to the destination node to be maximum, so that the interruption probability of the system can be reduced;
selecting the node with the maximum channel capacity for decoding and forwarding or direct transmission;
Imax＝max(IDT,Ii,i＝1～|Ω|) (10)
wherein, ImaxFor the selected maximum channel capacity, if Imax＝IDTIf the channel capacity of the link direct transmission is the maximum, the step S31 is skipped to, the direct transmission link S-D transmission is preferentially selected, and the relay node does not participate in the cooperative transmission; if Imax＝IiAnd i is 1 to omega, the selected ith relay node RiAfter the received signal is processed by the polar code continuous deleting decoding method, the channel polar coding is executed again and the signal is forwarded to a destination node D; at RiThe decoded and forwarded signal is represented as
Figure FDA0003578146610000041
Then D received signal
Figure FDA0003578146610000042
Is shown as
Figure FDA0003578146610000043
Wherein the content of the first and second substances,
Figure FDA0003578146610000044
is zero mean and variance is real
Figure FDA0003578146610000045
Is a complex Gaussian random variable representing Ri-additive white gaussian noise for the D-link.
2. The method for optimal relay node selection and power allocation under cooperative diversity system according to claim 1, wherein in step S5, the step of receiving signal by destination node is:
after receiving the signals of step S21 and step S42 or the signals forwarded by the link direct transmission of step S31, the destination node performs a maximum ratio combining method to combine all the received signals, and then sequentially performs demodulation and decoding by a continuous erasure decoding method to obtain a signal sequence estimated by the destination node, which is the final result.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104936251A (en) * 2015-04-28 2015-09-23 广西师范大学 Optimal power distribution based relay selection method and system of security cooperation
CN106413099A (en) * 2016-09-18 2017-02-15 西安电子科技大学 Optimal power allocation method of full duplex collaborative relay network

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101588627B (en) * 2009-06-23 2012-08-08 北京邮电大学 Optimal joint distribution method for power of source and relaying nodes in collaborative communication
US8774303B2 (en) * 2011-06-29 2014-07-08 Electronics And Telecommunications Research Institute Wireless communication method and apparatus using adaptive transmission polarization control
CN107172679A (en) * 2017-06-25 2017-09-15 广西师范大学 Relay selection method based on optimal power control in wireless EH collaborative networks
CN110213016B (en) * 2019-04-30 2021-09-21 杭州电子科技大学 Multi-relay selective polarization decoding forwarding method
CN110461034B (en) * 2019-07-19 2022-06-14 南京邮电大学 Power division factor optimization method based on energy collection multi-source relay cooperative communication system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104936251A (en) * 2015-04-28 2015-09-23 广西师范大学 Optimal power distribution based relay selection method and system of security cooperation
CN106413099A (en) * 2016-09-18 2017-02-15 西安电子科技大学 Optimal power allocation method of full duplex collaborative relay network

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