CN111030795B - Transmission method of time reversal wireless energy-carrying communication system under non-ideal channel - Google Patents

Transmission method of time reversal wireless energy-carrying communication system under non-ideal channel Download PDF

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CN111030795B
CN111030795B CN201911188194.1A CN201911188194A CN111030795B CN 111030795 B CN111030795 B CN 111030795B CN 201911188194 A CN201911188194 A CN 201911188194A CN 111030795 B CN111030795 B CN 111030795B
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CN111030795A (en
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董青
陈善学
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Chongqing University of Post and Telecommunications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H04L5/0055—Physical resource allocation for ACK/NACK
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H04L5/0057—Physical resource allocation for CQI

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Abstract

The invention discloses a transmission method of a time reversal wireless energy-carrying communication system under a non-ideal channel, which fully considers the influence of time reversal characteristics on the reliability and effectiveness of a multi-user multi-transmission single-receiving wireless energy-carrying communication system under non-ideal channel state information, enhances the effectiveness of the system by utilizing time reversal space-time focusing characteristics, and plans an optimization problem under the condition of non-ideal CSI through an energy-rate closed expression containing channel estimation errors.

Description

Transmission method of time reversal wireless energy-carrying communication system under non-ideal channel
Technical Field
The invention relates to the technical field of communication, in particular to a transmission method of a time reversal wireless energy-carrying communication system under a non-ideal channel.
Background
With the continuous evolution of communication technology, green communication and everything interconnection become the main development trend of future communication networks. Mass devices including mobile phones, sensors and household appliances are connected to a communication network, and functions of remote control, data collection, data exchange and the like are achieved. Low-cost and low-power consumption devices are also a typical type of future communication devices, and such devices will be increasingly used in the fields of Internet of Things (IoT) and Wireless Sensor Network (WSN). However, the energy required to operate such devices often comes from a fully pre-charged battery, which is difficult to recharge or replace due to cost, size, and application scenario constraints. Thus, it is a feasible and efficient solution to extract energy from the rf signals in the environment to charge each device while achieving secure reception of the information data. The method also lays a foundation for the concept of wireless energy-carrying communication.
In a Wireless energy Transfer (SWIPT) system, an EH path is generally used for energy collection, and an ID path is generally used for Information transmission. At present, the received radio frequency signal power can realize energy collection and information transmission in two ways, which are respectively: a Time division (TS) scheme for providing rf signals to each path in an alternating Time interval manner, and a power division (PS) scheme for simultaneously providing rf signals to each path according to a power division ratio.
However, the transmission scheme of the existing wireless energy-carrying communication system is based on ideal channel assumption, that is, the transmitting end can obtain accurate channel state information, and then effective collection of energy and information is realized by optimizing power division. However, in practice, due to the influence of factors such as Channel estimation error, and the State of the wireless Channel changes from moment to moment, it is very difficult to extract ideal Channel State Information (CSI) that can be completely matched with the Channel. Therefore, the following problems exist in the current solution: firstly, the influence of a non-ideal channel which is more in line with the reality on the SWIPT system is generally ignored; secondly, the influence of various interferences on multiple users is generally ignored in the existing scheme. This may result in a relaxation of the QoS constraints of the service quality of the SWIPT system, such that the transmission of the SWIPT system may not achieve the desired effect.
Disclosure of Invention
In order to solve the technical problem, the invention provides a transmission method of a time reversal wireless energy-carrying communication system under a non-ideal channel.
The technical scheme adopted by the invention is as follows:
a transmission method of a time reversal wireless energy-carrying communication system under a non-ideal channel comprises the following steps:
s1: a user terminal sends a detection pilot signal to a base station;
s2: the base station estimates the channel gain of the corresponding user terminal according to the received signal;
s3: calculating the optimal transmitting power p of the base station for transmitting data to the kth user terminal under the non-ideal channel by solving the first problem modelkThe first problem model is:
Figure BDA0002292913470000021
s.t.C1:Rk≥Rk *
C2:Ek≥Ek *
Figure BDA0002292913470000022
C4:0≤pk≤ppeak
Figure BDA0002292913470000023
Figure BDA0002292913470000024
and K e {1,2 … K }
Wherein P1 represents an objective function to be solved in the first problem model, C1, C2, C3, C4 and C5 represent constraints of an objective function P1 in the first problem model, and PkIndicating the transmission power, alpha, of the data transmitted by the base station to the corresponding kth user terminal in the kth time slotkRepresents the non-negative model variable corresponding to the kth user terminal, K represents the number of user terminals,
Figure BDA0002292913470000031
representing the channel gain for the kth user terminal in a non-ideal channel,
Figure BDA0002292913470000032
representing the antenna noise of the kth user terminal,
Figure BDA0002292913470000033
representing system noise, Rk *Minimum information reachable rate threshold, E, indicating the preset user terminal corresponding to the kth time slotk *Indicating the lowest received energy threshold, R, of the user terminal corresponding to the preset k-th time slotkRepresenting the actual information reachable rate of the user terminal corresponding to the k-th time slot under the non-ideal channel, EkRepresents the actual energy value of the user terminal corresponding to the k-th time slot under the non-ideal channel, P represents the preset maximum transmitting power of the base station,
Figure BDA0002292913470000034
indicating the inter-symbol interference power received by the kth user terminal in the irrational channel,
Figure BDA0002292913470000035
representing k usersThe intersymbol interference power received by the terminal under the non-ideal channel represents a weighting factor, p, biased to information transmission in the communication processpeakDenotes the peak power per time slot, 0 < beta < 1, Rk、Ek、
Figure BDA0002292913470000036
And
Figure BDA0002292913470000037
all are calculated by an expression containing channel estimation errors;
s4: the base station sets the transmitting power of the k time slot to pkAnd based on the transmitting power, sending the information data which is processed by time reversal to the corresponding user terminal;
s5: after receiving the information data, the user terminal transmits the signal power of beta times to the signal decoder, and transmits the signal power of 1-beta times to the energy collector.
Further, the step S3 is to calculate the transmission power p of the kth time slot of the base station by converting the first problem model into the second problem modelkThe second problem model is:
Figure BDA0002292913470000038
s.t.C6:Rk≥Rk *
C7:Ek≥Ek *
Figure BDA0002292913470000039
C9:0≤pk≤ppeak
Figure BDA00022929134700000310
and K e {1,2 … K }
Wherein P2 represents the object to be solved in the second problem modelThe scaling functions, C6, C7, C8, C9 and C10 represent the constraints of the objective function P2 in the second problem model, qkRepresenting non-negative intermediate variables, qk＝αkpk。
Further, in step S3, the CVX convex optimization toolbox is used to solve the objective function P2 to obtain the target solution Pk。
Further, the user terminal is a single antenna user terminal.
Further, the air conditioner is provided with a fan,
Figure BDA0002292913470000041
Rkand EkRespectively calculated by the following formula:
Figure BDA0002292913470000042
Figure BDA0002292913470000043
Figure BDA0002292913470000044
Figure BDA0002292913470000045
Figure BDA0002292913470000046
wherein the content of the first and second substances,
Figure BDA0002292913470000047
Figure BDA0002292913470000051
Figure BDA0002292913470000052
indicating the received power of the kth user terminal in the non-ideal channel,
Figure BDA0002292913470000053
expressing energy conversion efficiency, L expressing the total number of multipath, M expressing the total number of transmitting antennas of the base station, psi expressing a preset channel error, p'kWhich represents the transmit power of the user terminal k,
Figure BDA0002292913470000054
representing the noise power between the base station antenna x and the user terminal y,
Figure BDA0002292913470000055
gaussian white noise representing the r-th multipath between base station antenna i and user terminal j,
wherein (x, y) is { (M, L), (M ', L), (M, K +1-L), (M, L +1-L) }, (i, j, r) is { (M, K, L-1-L), (M, K, L), (M, K', L), (M ', K', L ') }, M, M' is {1,2 … M }, K, K 'is {1,2 … K }, L, L' is {1,2 … L },
Figure BDA0002292913470000056
representing a correlation matrix between base station antenna m and base station antenna m',
Figure BDA0002292913470000057
representing a correlation matrix between the transmit antennas of user terminal k and the transmit antennas of user terminal k' (R)U)kk'Representing a correlation matrix between user terminal k and user terminal k'.
The transmission method of the time reversal wireless energy-carrying communication system under the non-ideal channel fully considers the influence of time reversal characteristics on the reliability and effectiveness of the multi-user multi-sending single-receiving wireless energy-carrying communication system under the non-ideal channel state information, the effectiveness of the system is enhanced by utilizing the time reversal space-time focusing characteristics, the optimization problem is planned under the condition of non-ideal CSI through an energy-speed closed expression containing channel estimation errors, the energy collection efficiency can be improved under the condition of ensuring a certain information reachable speed through the method provided by the invention, and the reliability and the effectiveness of the system are improved compared with the traditional MISO-SWIPT.
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The invention will be further described with reference to the accompanying drawings and examples, in which:
fig. 1 is a schematic flow chart of a transmission method of a time-reversal wireless energy-carrying communication system under a non-ideal channel according to this embodiment;
FIG. 2 is a system block diagram of a time-reversal wireless energy-carrying communication system provided in the present embodiment;
fig. 3 is a graph of SINR versus SNR variation during the experiment. (ii) a
FIG. 4 is a diagram illustrating the variation of energy received by an energy harvester of a user terminal with the transmission power of a base station during an experiment;
fig. 5 is a schematic diagram of the variation of the energy received by the energy collector of the user terminal with the reachable information rate of the user terminal during the experiment.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments, it being understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.
The embodiment provides a transmission method of a time-reversal wireless energy-carrying communication system under a non-ideal channel, please refer to fig. 1, which includes the following steps:
s1: the user terminal transmits a sounding pilot signal to the base station.
S2: the base station estimates the channel gain of the corresponding user terminal according to the received signal.
In order to ensure that the user terminal can obtain energy maximally under the condition of a certain information reachable rate, a first problem model is preset.
S3: calculating the optimal data transmission of the base station to the kth user terminal under the non-ideal channel by solving the first problem modelTransmission power pkThe first problem model is:
Figure BDA0002292913470000061
s.t.C1:Rk≥Rk *
C2:Ek≥Ek *
Figure BDA0002292913470000062
C4:0≤pk≤ppeak
Figure BDA0002292913470000063
and K e {1,2 … K }
Wherein P1 represents the objective function to be solved in the first problem model, C1, C2, C3, C4 and C5 represent the constraint conditions of the objective function P1 in the first problem model, and PkIndicating the transmission power, alpha, of the data transmitted by the base station to the corresponding kth user terminal in the kth time slotkRepresents the non-negative model variable corresponding to the kth user terminal, K represents the number of user terminals,
Figure BDA0002292913470000064
representing the channel gain for the kth user terminal in a non-ideal channel,
Figure BDA0002292913470000071
representing the antenna noise of the kth user terminal,
Figure BDA0002292913470000072
representing system noise, Rk *Minimum information reachable rate threshold, E, indicating the preset user terminal corresponding to the kth time slotk *Indicating the lowest received energy threshold, R, of the user terminal corresponding to the preset k-th time slotkIndicating that the user terminal corresponding to the k-th time slot is in the irrational stateAchievable rate of actual information in desired channel, EkRepresents the actual energy value of the user terminal corresponding to the k-th time slot under the non-ideal channel, P represents the preset maximum transmitting power of the base station,
Figure BDA0002292913470000073
indicating the inter-symbol interference power received by the kth user terminal in the irrational channel,
Figure BDA0002292913470000074
represents the intersymbol interference power received by k user terminals under a non-ideal channel, represents a weighting factor biased to information transmission in the communication process, and represents ppeakDenotes the peak power per time slot, 0 < beta < 1, Rk、Ek、
Figure BDA0002292913470000075
And
Figure BDA0002292913470000076
are calculated by an expression containing channel estimation errors.
The first problem model is a non-convex optimization problem, and in the calculation process, a non-negative variable q can be introducedkTo ensure its continuity, convert the non-convex optimization problem into a convex optimization problem, wherein q isk＝αkpk(k 1, k), that is, the first problem model can be converted into a second problem model to calculate the transmission power p of the kth time slot of the base station in step S3kWherein the second problem model is:
Figure BDA0002292913470000077
s.t.C6:Rk≥Rk *
C7:Ek≥Ek *
Figure BDA0002292913470000078
C9:0≤pk≤ppeak
Figure BDA0002292913470000079
and K e {1,2 … K }
Wherein P2 represents the objective function to be solved in the second problem model, C6, C7, C8, C9 and C10 represent the constraint conditions of the objective function P2 in the second problem model, qkRepresenting non-negative intermediate variables, qk＝αkpk。
In step S3, the CVX convex optimization toolbox may be used to solve the objective function P2 to obtain the target solution Pk. It should be noted that step S3 in this embodiment may be executed by the base station, that is, p may be calculated by the base stationkHowever, in other embodiments pkOr can be calculated by another specially arranged computing terminal which calculates pkThen p iskAnd sending the data to the base station for setting the transmission power of the base station.
S4: the base station sets the transmitting power of the k time slot to pkAnd transmitting the information data subjected to the time reversal processing to the corresponding user terminal based on the transmission power.
Due to the Time-space focusing characteristic of TR (Time Reversal), the transmitted signal of the base station can collect most of the useful signal power in a short Time interval and form a focus at the target.
S5: after receiving the information data, the user terminal transmits the signal power of beta times to the signal decoder, and transmits the signal power of 1-beta times to the energy collector.
The user terminal in this embodiment may employ a PS receiver.
Referring to fig. 2, in the system block diagram of the time reversal wireless energy-carrying communication system provided in this embodiment, after receiving TR-modulated signal power transmitted by the base station, the user terminal in fig. 2 transfers the β portion of the signal power to the signal receiver (i.e., signal decoder), and transfers the 1- β portion of the signal power to the energy receiver (i.e., energy collector).
It should be noted that, preferably, the user terminal in this embodiment is a single-antenna user terminal.
Assuming that M transmitting antennas are used at a transmitting end (base station) and K receiving antennas are used at a legal receiving end (user terminal side), that is, K user terminals are provided in a system, each user terminal is a single-antenna user terminal, Channel Impulse Response (CIR) between a transmitting antenna M ∈ (1, M) at the transmitting end and a receiving antenna K ∈ (1, K) at the legal receiving end can be obtained through channel estimation, CIR in this embodiment can be recorded as:
Figure BDA0002292913470000081
wherein the content of the first and second substances,
Figure BDA0002292913470000082
and
Figure BDA0002292913470000083
respectively the amplitude and delay of the ith tap. Vector h with CSI discrete in time domainmk∈CL ×1Particular of E [ h ]mk[l]]＝0，
Figure BDA0002292913470000084
E[·]Indicating a signal expectation.
The signal received by a single antenna user terminal can be written as:
Figure BDA0002292913470000091
corresponds to the detailed description of each part in the above formula, wherein skAnd sk'Symbols to be transmitted (E (| s! y) representing the kth user and the kth' user, respectively2) 1). Modeling a multipath channel as a tapped delay line model, i.e. assuming hmk∈CL×1Is the m-th transmitting antenna and k-th userChannel state matrix E (| h) between antennasmk[l]|)＝0，
Figure BDA0002292913470000092
hmk∈CL×1Is introduced into the antenna noise of the system
Figure BDA0002292913470000093
And due to hmkIf it belongs to the vector set of complex numbers, then the complex channel h is pairedm[l]Performing complex conjugate and timing inversion operations
Figure BDA0002292913470000094
Thus, gmThe value of each tap can be written as:
Figure BDA0002292913470000095
in order to achieve the target energy collection effect under the existing non-ideal CSI condition, the method provided by the embodiment utilizes the TR space-time focusing characteristic to make up for the disadvantages of the swapt technology.
The wireless energy-carrying communication system provided by the embodiment comprises a base station with M transmitting antennas and N single-antenna user terminals. In a multipath channel, the maximum length of each channel impulse response is L. In the information sending stage, a sending party firstly completes the time reversal process of a signal under the condition of non-ideal CSI through a time reversal mirror, and the process is expanded and analyzed as follows:
since in practical applications the true channel is an unknown parameter, the effect of channel error estimation is modeled as follows:
Figure BDA0002292913470000096
Figure BDA0002292913470000097
and emk∈CL×1Respectively representing estimatesThe channel and error vectors, which are distributed independently of each other and with a non-negative error factor ψ, can be found to have the following characteristics:
E[|emk[l]|2]＝ψE[||hmk[l]|2]
Figure BDA0002292913470000098
TR technology based on non-ideal channel and obtained by combining the two formulas
Figure BDA0002292913470000099
Is represented by a symbol containing transmission power p'kThe non-ideal channel TR pre-filter vector, the value of each tap being defined as:
Figure BDA00022929134700000910
Figure BDA0002292913470000101
is hmk[l]In non-ideal channel conditions.
Thus, the signal received by the kth user terminal is
Figure BDA0002292913470000102
The SINR expression of the present system is:
Figure BDA0002292913470000103
the received power of each user terminal may be expressed as:
Figure BDA0002292913470000104
the power of the intersymbol interference may be expressed as:
Figure BDA0002292913470000105
the power of the inter-user interference can be expressed as:
Figure BDA0002292913470000106
the specific derivation process of the SINR (Signal to Interference plus Noise Ratio) is as follows
Figure BDA0002292913470000107
The method provided by the embodiment fully considers the influence of the channel error on the transmission, introduces the channel error in the derivation process, and further derives each expression, and each part is specifically derived as follows:
Figure BDA0002292913470000108
Figure BDA0002292913470000109
Figure BDA0002292913470000111
therefore, under the assumptions of the multipath error channel and the correlation given above, in the present embodiment
Figure BDA0002292913470000112
Figure BDA0002292913470000113
RkAnd EkCan be divided intoRespectively calculated by the following formula:
Figure BDA0002292913470000114
Figure BDA0002292913470000115
Figure BDA0002292913470000116
Figure BDA0002292913470000117
Figure BDA0002292913470000118
wherein the content of the first and second substances,
Figure BDA0002292913470000119
Figure BDA00022929134700001110
Figure BDA00022929134700001111
indicating the received power of the kth user terminal in the non-ideal channel,
Figure BDA00022929134700001112
expressing energy conversion efficiency, L expressing the total number of multipath, M expressing the total number of transmitting antennas of the base station, psi expressing a preset channel error, p'kWhich represents the transmit power of the user terminal k,
Figure BDA0002292913470000121
representing the noise power between the base station antenna x and the user terminal y,
Figure BDA0002292913470000122
gaussian white noise representing the r-th multipath between base station antenna i and user terminal j,
wherein (x, y) is { (M, L), (M ', L), (M, K +1-L), (M, L +1-L) }, (i, j, r) is { (M, K, L-1-L), (M, K, L), (M, K', L), (M ', K', L ') }, M, M' is {1,2 … M }, K, K 'is {1,2 … K }, L, L' is {1,2 … L },
Figure BDA0002292913470000123
representing a correlation matrix between base station antenna m and base station antenna m',
Figure BDA0002292913470000124
representing a correlation matrix between the transmit antennas of user terminal k and the transmit antennas of user terminal k' (R)U)kk'Representing a correlation matrix between user terminal k and user terminal k'.
The above calculation
Figure BDA0002292913470000125
RkAnd EkThe calculation formula fully considers the influence of channel errors, thereby improving the reliability and the effectiveness of the system.
In order to verify the effectiveness of the method provided by the embodiment, the transmission method of the wireless energy-carrying communication system based on the TR under different conditions is subjected to simulation verification of a theoretical derivation value, the variation trend of the system performance under the conditions is analyzed, finally, the performance is compared with the transmission scheme of the traditional wireless energy-carrying communication system, and the influence of the robustness scheme added with the TR and convex optimization on the system performance is researched. The parameters in the experimental procedure were: when m ═ m' (R)T)mm'(R ≠ m ≠ 1T)mm'＝ρT，ρTThe correlation degree between the m-th antenna and the m' -th antenna is expressed, and other common settings are that the number of taps L is 110, and the average transmission power p of the base station is 1W.
Relevant experimental simulations were performed.
Fig. 3 is a graph of SINR with SNR under two conditions of an ideal channel and a non-ideal channel in the time reversal process, and the channel error factor ψ in fig. 3 is 0.5, that is, under the non-ideal channel condition in practical application, the system is weakened to some extent.
Fig. 4 is a simulation diagram of the conventional wireless energy-carrying communication system transmission method under the ideal channel condition and the TR-based wireless energy-carrying communication system transmission method under the non-ideal channel condition provided by this embodiment in the experimental process when the correlation between the transmitting antennas of the base station is 0 (the antennas are independent of each other), which shows a schematic diagram of the energy received by the energy collector of the user terminal changing with the transmitting power of the user terminal. The specific change trend is as follows: when the transmission power of the base station is increased, the energy received by the energy receiver of the user terminal is also increased, but by the method provided by the embodiment, the energy efficiency is better than that of the conventional scheme under any transmission power, and the effectiveness of the method provided by the embodiment is verified.
Fig. 5 is a graph obtained by simulation when the correlation between the transmitting antennas of the base station is 0 (independent of each other), the power division ratio, and the number of antennas are changed. There are two transmission schemes, one is the transmission scheme (non-ideal channel robustness method) of the TR-based wireless energy-carrying communication system provided in this embodiment, and the other is the transmission scheme of the conventional ideal channel wireless energy-carrying communication system, as can be seen from the figure, when the power division ratio is small (the achievable information rate is small), the energy collected by the TR-based wireless energy-carrying communication system adopting the robustness scheme approaches the conventional scheme of increasing a certain number of antennas, and when the number of antennas is not changed, the robustness scheme is larger than the energy collected by the transmission scheme of the conventional ideal channel wireless energy-carrying communication system in both the achievable information rate and the collected energy. When the system performance needs to be considered integrally from two aspects of the reachable information rate and the collected energy, the size of an average rate-energy area in the robustness scheme is close to a square frame, and the area of the average rate-energy area is larger than that of the traditional scheme, so that the system can meet a certain reachable information rate and can also collect energy with a certain size. Compared with the conventional transmission method, the transmission method provided by the embodiment obviously improves the energy collection efficiency.
Aiming at the limitation of mutually independent antennas in SWIPT-MISO power division and hypothesis, the TR under the non-ideal channel condition is combined with the SWIPT-MISO, the energy collection of the TR and the SWIPT-MISO is optimized by utilizing a convex optimization algorithm, and a novel SWIPT-MISO transmission method based on the TR is provided. By the method, a PS receiver can be adopted, and a Clonecker model is introduced to derive an average speed-energy area theoretical expression under a multipath channel under the condition that the correlation of the antenna is considered. Simulation results show that when conditions such as the number of antennas at the transmitting end, the power division ratio and the like are changed, the obtained theoretical value and the simulated value are always on the same curve, the correctness of the derivation process of the method provided by the embodiment is verified, and the improvement effect of introducing the TR technology on the system performance is fully displayed in the performance comparison with the traditional SWIPT-MISO transmission scheme. On the other hand, the TR and the SWIPT-MISO are combined, so that the advantages of the TR and the SWIPT-MISO are complemented, and the ideal effect is achieved. The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal (such as a mobile phone, a computer, a server, an air conditioner, or a network device) to execute the method according to the embodiments of the present invention.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (4)

1. A transmission method for a time-reversal wireless energy-carrying communication system under a non-ideal channel, comprising the steps of:
s1: a user terminal sends a detection pilot signal to a base station;
s2: the base station estimates the channel gain of the corresponding user terminal according to the received signal;
s3: calculating the optimal transmitting power p of the base station for transmitting data to the kth user terminal under the non-ideal channel by solving the first problem modelkThe first problem model is:
P1:
Figure FDA0003461753790000011
s.t.C1:Rk≥Rk *
C2:Ek≥Ek *
C3:
Figure FDA0003461753790000012
C4:0≤pk≤ppeak
C5:
Figure FDA0003461753790000013
and k e {1,2L K }
Wherein P1 represents an objective function to be solved in the first problem model, C1, C2, C3, C4 and C5 represent constraints of an objective function P1 in the first problem model, and PkIndicating the number of transmissions of the base station to the corresponding kth user terminal in the kth time slotAccording to the transmission power, αkRepresents the non-negative model variable corresponding to the kth user terminal, K represents the number of user terminals,
Figure FDA0003461753790000014
representing the channel gain for the kth user terminal in a non-ideal channel,
Figure FDA0003461753790000015
representing the antenna noise of the kth user terminal,
Figure FDA0003461753790000016
representing system noise, Rk *Minimum information reachable rate threshold, E, indicating the preset user terminal corresponding to the kth time slotk *Indicating the lowest received energy threshold, R, of the user terminal corresponding to the preset k-th time slotkRepresenting the actual information reachable rate of the user terminal corresponding to the k-th time slot under the non-ideal channel, EkRepresents the actual energy value of the user terminal corresponding to the k-th time slot under the non-ideal channel, P represents the preset maximum transmitting power of the base station,
Figure FDA0003461753790000017
indicating the inter-symbol interference power received by the kth user terminal in the irrational channel,
Figure FDA0003461753790000018
represents the intersymbol interference power received by k user terminals under a non-ideal channel, represents a weighting factor biased to information transmission in the communication process, and represents ppeakDenotes the peak power per time slot, 0 < beta < 1, Rk、Ek、
Figure FDA0003461753790000021
And
Figure FDA0003461753790000022
all are calculated by an expression containing channel estimation errors;
Figure FDA0003461753790000023
Figure FDA0003461753790000024
Figure FDA0003461753790000025
Figure FDA0003461753790000026
Figure FDA0003461753790000027
wherein the content of the first and second substances,
Figure FDA0003461753790000028
Figure FDA0003461753790000029
Figure FDA00034617537900000210
indicating the received power of the kth user terminal in the non-ideal channel,
Figure FDA00034617537900000211
expressing energy conversion efficiency, L expressing the total number of multipath, M expressing the total number of transmitting antennas of the base station, psi expressing a preset channel error, p'kWhich represents the transmit power of the user terminal k,
Figure FDA0003461753790000031
representing the noise power between the base station antenna x and the user terminal y,
Figure FDA0003461753790000032
gaussian white noise representing the r-th multipath between base station antenna i and user terminal j,
wherein (x, y) is { (m, L), (m ', L), (m, k +1-L), (m, L +1-L) }, (i, j, r) is { (m, k, L-1-L), (m, k, L), (m, k', L), (m ', k', L ') }, m, m' is {1,2L M }, k, k 'is {1,2L K }, L, L' is {1,2L L },
Figure FDA0003461753790000033
representing a correlation matrix between base station antenna m and base station antenna m',
Figure FDA0003461753790000034
representing a correlation matrix between the transmit antennas of user terminal k and the transmit antennas of user terminal k' (R)U)kk'Representing a correlation matrix between user terminal k and user terminal k';
s4: the base station sets the transmitting power of the k time slot to pkAnd based on the transmitting power, sending the information data which is processed by time reversal to the corresponding user terminal;
s5: after receiving the information data, the user terminal transmits the signal power of beta times to the signal decoder, and transmits the signal power of 1-beta times to the energy collector.
2. The transmission method of a time-reversal wireless energy-carrying communication system under non-ideal channel as claimed in claim 1, wherein the step S3 is implemented by converting the first problem model into a second problem model to calculate the transmission power p of the kth time slot of the base stationkThe second problem model is:
P2:
Figure FDA0003461753790000035
s.t.C6:Rk≥Rk *
C7:Ek≥Ek *
C8:
Figure FDA0003461753790000036
C9:0≤pk≤ppeak
C10:
Figure FDA0003461753790000037
and k e {1,2L K }
Wherein P2 represents an objective function to be solved in the second problem model, C6, C7, C8, C9 and C10 represent constraints of an objective function P2 in the second problem model, and q represents a constraint condition of an objective function P2 in the second problem modelkRepresenting non-negative intermediate variables, qk＝αkpk。
3. The transmission method of time-reversal wireless energy-carrying communication system under non-ideal channel as claimed in claim 2, wherein the target solution P is obtained by solving the objective function P2 through CVX convex optimization toolbox in step S3k。
4. The transmission method for a time-reversal wireless energy-carrying communication system under non-ideal channels as claimed in claim 1, wherein the user terminal is a single-antenna user terminal.
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