CN106211305B - A kind of power distribution method in amplification forwarding bidirectional relay system - Google Patents
A kind of power distribution method in amplification forwarding bidirectional relay system Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/30—TPC using constraints in the total amount of available transmission power
- H04W52/34—TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
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Abstract
The present invention relates to the power distribution methods in a kind of amplification forwarding bidirectional relay system, using the total frequency spectrum efficiency of bidirectional relay system as point of penetration, introduce total power constraint, it establishes system total frequency spectrum efficiency and maximizes model, a series of geometry optimizations are solved the problems, such as using successive approximation algorithm, find out optimal power parameterPromote the spectrum efficiency of amplification forwarding bidirectional relay system.
Description
Technical Field
The invention relates to the field of communication, in particular to a power distribution method in an amplifying and forwarding bidirectional relay system.
Background
The bidirectional relay system effectively expands the coverage area of a network, provides space diversity and reduces the energy loss of the system by arranging the relay station between the base station and the user or between the users. Compared with a one-way relay system, the two-way relay system can improve the spectral efficiency by about one time, but the system also has the problem of serious interference among users. According to the prior literature, there are many methods for eliminating the interference between users, such as dirty paper coding and some interference coordination techniques. However, these methods have high algorithm complexity and are not easy to implement in practical systems. Meanwhile, large-scale antenna technology has received much attention in the industry because of its excellent interference suppression capability. Therefore, deploying a large-scale antenna at the relay end is a very potential and simple and feasible interference coordination method.
The channel of the bidirectional relay system with the large-scale antenna is gradually orthogonal, the resolution of the antenna array is improved, and the spectral efficiency of the system can be obviously improved. However, as the explosive mobile data traffic increases, higher requirements are put on the spectrum efficiency of the bidirectional relay system. The method for improving the spectrum efficiency of the bidirectional relay system in the existing literature mainly includes: (1) optimizing a beam former to control the transmitting direction of the beam at the base station end; (2) selecting an antenna at a relay terminal, transmitting data by using an optimal channel or scheduling a user, and scheduling the user with good channel condition to transmit data; (3) the transmission power of the user and the relay is adjusted in real time using the channel instantaneous state information.
After analyzing the existing method, the inventor finds that: the methods mentioned in the literature are either too complex, lacking in feasibility, or narrow in application range, with certain limitations. The method (1) needs to obtain all channel information and solve the optimal beam former, and is relatively complex and difficult to implement; in the method (2), the communication and coordination between the relay and the user are required to be introduced for antenna selection or user scheduling, so that unnecessary expenses are increased; the method (3) requires real-time detection of channel change, and cannot be implemented in a high-speed mobile system with fast channel change.
Disclosure of Invention
The invention aims to provide a power distribution method in an amplify-and-forward bidirectional relay system aiming at the defects of the prior art, and the spectrum efficiency of the amplify-and-forward bidirectional relay system is improved.
The technical scheme provided by the invention for solving the technical problems is as follows:
a power distribution method in an amplify-and-forward two-way relay system comprises the following steps:
1) n pairs of users TA,iAnd TB,iCoherence time tau at each channelcThe internal simultaneous transmissions are orthogonal to each other and have a length taupPilot sequence to relay TRWherein i is more than or equal to 1 and less than or equal to N; the relay TRM antennas are equipped;
2) relay TRReceiving N pairs of users TA,iAnd TB,iAfter the pilot frequency sequence is sent, MMSE linear estimation is used according to the pilot frequency sequence information to obtain channel state information;
3) calculating user T according to channel state informationA,iSpectral efficiency R ofA,iAnd user TB,iSpectral efficiency R ofB,iTotal spectral efficiency
4) Converting total spectral efficiency intoEstablishing a power optimization problem; a power control algorithm is introduced to solve the optimization problem to obtain a power distribution parameter which enables the total spectral efficiency R to reach the maximumAndsaid p isA,iFor user TA,iTransmit power of pB,iFor user TB,iTransmit power of prFor relaying TRThe transmit power of (a);
5) amplifier-forward two-way relay system utilizing optimal power distribution parametersAndand carrying out data transmission.
The technical scheme provides a method with guiding significance for power distribution in the amplifying and forwarding bidirectional relay system, namely channel state information is estimated through a relay, an expression of total spectrum efficiency is calculated, and under the condition that the system obeys total power constraint, the transmission power of the relay and N to users is optimized simultaneously, so that the total spectrum efficiency of the system is maximum. Compared with the traditional method for improving the spectrum efficiency such as beam forming or antenna selection, the method has the characteristics of low algorithm complexity and simplicity and easiness in implementation, and meets the requirement for explosive mobile data growth in the future.
The channel state information in the step 2) comprises a user TA,iAnd relay TRUser TB,iAnd relay TRThe channel state information of (a) is specifically:
wherein, gAR,iAnd gRB,iRespectively represent users TA,i、TB,iAnd relay TRThe channel vector between the two channels of the channel vector,andrespectively represent users TA,i、TB,iAnd relay TREstimated channel vector of (d), eAR,iAnd eRB,iIs the estimated error vector of the channel.
The estimated channel vectorAndeach element in (1) respectively satisfies the mean value of 0 and the variance ofAnda complex Gaussian distribution of (A), wherein βAR,iFor user TA,iAnd relay TRLarge scale fading factor of βRB,iFor user TB,iAnd relay TRLarge scale fading factor, ppIs the transmit power of the pilot sequence.
The user T in the step 3)A,iSpectral efficiency R ofA,iComprises the following steps:
in the formula,
wherein, ai,j，bi,j，ci,j，di,jand eiIs a known constant value.
The user T in the step 3)B,iSpectral efficiency R ofB,iComprises the following steps:
in the formula,
wherein, andis a known constant value.
The power optimization problem established in the step 4) is as follows:
maximize R
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
wherein P is the total power constraint of the amplify-and-forward bidirectional relay system.
Further, the establishing of the power optimization problem is equivalently transformed into:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
the power optimization problem is an assisted geometric programming problem, and a successive approximation algorithm can be used for solving a series of geometric programming problems to obtain an approximate solution of the original problem.
The power control algorithm in the step 4) is a successive approximation algorithm, and comprises the following steps:
a) initialization: defining parameters epsilon and theta; let k equal to 1, set initial value
b) Iteration k: computingAnd
the following geometric planning problem is then solved:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
the optimal solution at the kth iteration is obtained and is expressed asAnd
c) iteration stop criterion: if it is notOrThe iteration is stopped and the process is stopped,the solution of the geometric programming problem at the moment is output asAndotherwise, executing step d);
d) updating an initial value: order toAnd k ═ k + 1; step b) is performed.
The data transmission in the step 5) refers to: user TA,iAnd TB,iRespectively transmitting power ofAndto relay TR(ii) a Relay TRAfter receiving the signal, the linear processing of maximum ratio combination/maximum ratio transmission is carried out and the signal is processed in the following wayForwards the power amplification to the user TA,iAnd TB,iImplementing user TA,iAnd TB,iTo communicate between them.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention fully combines the two-way relay system and the large-scale antenna technology, not only utilizes the advantages of wide coverage area and low energy loss of the two-way relay system, but also has stronger interference coordination capability of the large-scale antenna.
(2) The invention aims at the channel state information estimated by the relay terminal to obtain the expression of the total spectrum efficiency, and obtains the user distribution parameters by solving a series of geometric programming problems by utilizing a successive approximation algorithmThe spectrum efficiency of the system is maximized, and the requirements of future mobile communication systems are met.
Drawings
Fig. 1 is a communication structure diagram in an amplify-and-forward bidirectional relay system according to an embodiment of the present invention;
fig. 2 is a flowchart of a power distribution method of an amplify-and-forward bidirectional relay system according to an embodiment of the present invention;
fig. 3 is a comparison curve of spectral efficiency of the power allocation method and the average power allocation method in the embodiment of the present invention.
Detailed Description
The invention is further illustrated by the following examples and figures of the specification.
An amplify-and-forward two-way relay system as shown in fig. 1, which includes a relay T equipped with M antennasRAnd working in the mode of amplifying and forwarding, N pairs of single-antenna users TA,iAnd TB,i(ii) a User TA,iAnd TB,iBy means of relay TRThe communication is realized, the scattering of all channels is sufficient, and the Rayleigh fading model is satisfied.
The power allocation method shown in fig. 2 includes the following steps:
1) n pairs of users TA,iAnd TB,iCoherence time tau at each channelcThe internal simultaneous transmissions are orthogonal to each other and have a length taupPilot sequence to relay TRWherein i is more than or equal to 1 and less than or equal to N; the relay TRM antennas are equipped;
2) relay TRReceiving N pairs of users TA,iAnd TB,iAfter the pilot sequence is transmitted, MMSE linear estimation is used according to the pilot sequence information,obtaining channel state information;
3) calculating user T according to channel state informationA,iSpectral efficiency R ofA,iAnd user TB,iSpectral efficiency R ofB,iTotal spectral efficiency
4) Converting total spectral efficiency intoEstablishing a power optimization problem; a power control algorithm is introduced to solve the optimization problem to obtain a power distribution parameter which enables the total spectral efficiency R to reach the maximumAndsaid p isA,iFor user TA,iTransmit power of pB,iFor user TB,iTransmit power of prFor relaying TRThe transmit power of (a);
5) amplifier-forward two-way relay system utilizing optimal power distribution parametersAndand carrying out data transmission.
The channel state information in the step 2) comprises a user TA,iAnd relay TRUser TB,iAnd relay TRThe channel state information of (a) is specifically:
wherein, gAR,iAnd gRB,iRespectively represent users TA,i、TB,iAnd relay TRThe channel vector between the two channels of the channel vector,andrespectively represent users TA,i、TB,iAnd relay TREstimated channel vector of (d), eAR,iAnd eRB,iIs the estimated error vector of the channel.
The estimated channel vectorAndeach element in (1) respectively satisfies the mean value of 0 and the variance ofAnda complex Gaussian distribution of (A), wherein βAR,iFor user TA,iAnd relay TRLarge scale fading factor of βRB,iFor user TB,iAnd relay TRLarge scale fading factor, ppIs the transmit power of the pilot sequence.
The user T in the step 3)A,iSpectral efficiency R ofA,iComprises the following steps:
in the formula,
wherein, ai,j，bi,j，ci,j，di,jand eiIs a known constant value.
The user T in the step 3)B,iSpectral efficiency R ofB,iComprises the following steps:
in the formula,
wherein, andis a known constant value.
The power optimization problem established in the step 4) is as follows:
maximize R
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
wherein P is the total power constraint of the amplify-and-forward bidirectional relay system.
Further, the establishing of the power optimization problem is equivalently transformed into:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
the power optimization problem is an assisted geometric programming problem, and a successive approximation algorithm can be used for solving a series of geometric programming problems to obtain an approximate solution of the original problem.
The power control algorithm in the step 4) is a successive approximation algorithm, and comprises the following steps:
a) initialization: defining parameters epsilon and theta; let k equal to 1, set initial value
b) Iteration k: computingAnd
the following geometric planning problem is then solved:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
the optimal solution at the kth iteration is obtained and is expressed asAnd
c) iteration stop criterion: if it is notOrThe iteration is stopped, and the solution of the geometric programming problem at the moment is output asAndotherwise, executing step d);
d) updating an initial value: order toAnd k ═ k + 1; step b) is performed.
The data transmission in the step 5) refers to: user TA,iAnd TB,iRespectively transmitting power ofAndto relay TR(ii) a Relay TRAfter receiving the signal, the linear processing of maximum ratio combination/maximum ratio transmission is carried out and the signal is processed in the following wayForwards the power amplification to the user TA,iAnd TB,iImplementing user TA,iAnd TB,iTo communicate between them.
The embodiment achieves the technical effects that:
fig. 3 is a comparison effect diagram of the successive approximation algorithm and the average power allocation algorithm in this embodiment. Wherein an amplification is arrangedIn the forwarding bidirectional relay system, N is randomly distributed to 5 pairs of users, and the large-scale fading factor is βAR＝[0.2688,0.0368,0.00025,0.1398,0.0047]And βRB＝[0.0003,0.00025,0.0050,0.0794,0.0001]The total power constraint is P-10 dB, and the pilot transmission power is Pp＝10dB。
As can be seen from the figure, compared with the average power distribution scenario, the optimal power distribution can effectively improve the spectrum efficiency of the amplify-and-forward relay system, and the more antennas are configured for relaying, the more obvious the improvement effect is.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be covered by the present invention.
Claims (5)
1. A power distribution method in an amplify-and-forward two-way relay system is characterized by comprising the following steps:
1) n pairs of users TA,iAnd TB,iCoherence time tau at each channelcThe internal simultaneous transmissions are orthogonal to each other and have a length taupPilot sequence to relay TRWherein i is more than or equal to 1 and less than or equal to N; the relay TRM antennas are equipped;
2) relay TRReceiving N pairs of users TA,iAnd TB,iAfter the transmitted pilot sequence, the pilot sequence information is usedMMSE linear estimation is carried out to obtain channel state information;
the channel state information in the step 2) comprises a user TA,iAnd relay TRUser TB,iAnd relay TRThe channel state information of (a) is specifically:
wherein, gAR,iAnd gRB,iRespectively represent users TA,i、TB,iAnd relay TRThe channel vector between the two channels of the channel vector,andrespectively represent users TA,i、TB,iAnd relay TREstimated channel vector of (d), eAR,iAnd eRB,iAn estimated error vector for the channel;
the estimated channel vectorAndeach element in (1) respectively satisfies the mean value of 0 and the variance ofAnda complex Gaussian distribution of (A), wherein βAR,iFor user TA,iAnd relay TRLarge scale fading factor of βRB,iFor user TB,iAnd relay TRLarge scale fading factor, ppIs the transmit power of the pilot sequence;
3) calculating user T according to channel state informationA,iSpectral efficiency R ofA,iAnd user TB,iSpectral efficiency R ofB,iTotal spectral efficiency
The user T in the step 3)A,iSpectral efficiency R ofA,iComprises the following steps:
in the formula,
wherein,
the user T in the step 3)B,iSpectral efficiency R ofB,iComprises the following steps:
in the formula,
wherein,
4) converting total spectral efficiency intoEstablishing a power optimization problem; a power control algorithm is introduced to solve the optimization problem to obtain a power distribution parameter which enables the total spectral efficiency R to reach the maximumAndsaid p isA,iFor user TA,iTransmit power of pB,iFor user TB,iTransmit power of prFor relaying TRThe transmit power of (a);
5) amplifier-forward two-way relay system utilizing optimal power distribution parametersAndand carrying out data transmission.
2. The method for allocating power in the amplify-and-forward bidirectional relay system according to claim 1, wherein the power optimization problem established in step 4) is:
maximize R
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
wherein P is the total power constraint of the amplify-and-forward bidirectional relay system.
3. The method of claim 2, wherein the establishing the power optimization problem is equivalently transformed into:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0。
4. the power allocation method in the amplify-and-forward bidirectional relay system according to claim 3, wherein the power control algorithm in step 4) is a successive approximation algorithm, comprising:
a) initialization: defining parameters epsilon and theta; let k equal to 1, set initial value
b) Iteration k: computingAnd
the following geometric planning problem is then solved:
pA,i≥0,pB,i≥0,i＝1,...,N
pr≥0
the optimal solution at the kth iteration is obtained and is expressed asAnd
c) iteration stop criterion: if it is notOrThe iteration is stopped, and the solution of the geometric programming problem at the moment is output asAndotherwise, executing step d);
d) updating an initial value: order toAnd k ═ k + 1; step b) is performed.
5. The power allocation method in the amplify-and-forward bidirectional relay system according to claim 1, wherein the data transmission in step 5) refers to: user TA,iAnd TB,iRespectively transmitting power ofAndto relay TR(ii) a Relay TRAfter receiving the signal, the linear processing of maximum ratio combination/maximum ratio transmission is carried out and the signal is processed in the following wayForwards the power amplification to the user TA,iAnd TB,iImplementing user TA,iAnd TB,iTo communicate between them.
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| KR20110020352A (en) * | 2009-08-24 | 2011-03-03 | 서울대학교산학협력단 | Apparatus and method of cooperative interference mitigation and resource management in wireless dual-hop relay systems with multiple antennas |
| JP2011250023A (en) * | 2010-05-25 | 2011-12-08 | Panasonic Electric Works Co Ltd | Wireless communication system |
| JP2012165275A (en) * | 2011-02-08 | 2012-08-30 | Nippon Telegr & Teleph Corp <Ntt> | Radio communication system, transceiver station, and relay station |
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| KR20110020352A (en) * | 2009-08-24 | 2011-03-03 | 서울대학교산학협력단 | Apparatus and method of cooperative interference mitigation and resource management in wireless dual-hop relay systems with multiple antennas |
| JP2011250023A (en) * | 2010-05-25 | 2011-12-08 | Panasonic Electric Works Co Ltd | Wireless communication system |
| JP2012165275A (en) * | 2011-02-08 | 2012-08-30 | Nippon Telegr & Teleph Corp <Ntt> | Radio communication system, transceiver station, and relay station |
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