CN110167179B - Method for prolonging service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation - Google Patents
Method for prolonging service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation Download PDFInfo
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Abstract
The invention discloses a service life prolonging method of energy-limited intelligent sensing equipment based on radio frequency energy compensation, which comprises the steps of establishing an intelligent sensing equipment network model; the intelligent terminal with sufficient energy initializes power division and time slot division, calculates the data transmission quantity of the intelligent sensing equipment with limited energy forwarded by the intelligent terminal and reports the data transmission quantity; the cellular base station counts the data transmission quantity of the intelligent terminals with sufficient energy, calculates the frequency band share of each intelligent terminal with sufficient energy and issues the frequency band share; the intelligent terminal with sufficient energy calculates power division and time slot division which maximize the self utility, calculates the data transmission quantity of the intelligent sensing equipment with limited energy and reports the data transmission quantity; repeating the steps until the transmission quantity of the data forwarded by all intelligent terminals with sufficient energy is maximum; and carrying out data transmission according to the optimal result. The method and the device can reasonably divide power and time slots for the intelligent terminal with sufficient energy and enable the intelligent terminal to obtain the corresponding spectrum share, and finally achieve the purpose of prolonging the service life of the intelligent sensing equipment.
Description
Technical Field
The invention particularly relates to a method for prolonging the service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation.
Background
With the development of economic technology, smart cities have also been developed. There are a large number of smart sensing devices in smart cities for sensing ambient data, most of which are powered by portable batteries and thus have limited runtime. For small amounts of data that need to be reported regularly, such as sensed city air quality data, city pipe system status monitoring data, public building structure monitoring data, city bridge structure monitoring data, if the smart sensing device is equipped with a Low Power Wide Area interface (LPWA) (e.g., General Packet Radio Service (GPRS) or Narrow Band Internet of Things (NB-IoT)), it will be able to report these sensed data to the data center easily through the cellular base station. However, as the number of such reports increases, the battery life of the smart aware device will gradually decrease. Especially when it is far away from the base station or at the edge of the cell coverage area, the energy consumption of the battery will be faster and may lead to greater interference between adjacent cells.
The life of the smart sensor device can be extended by replacing the battery, but this can be laborious, expensive, or even impossible (e.g. medical implant devices: the power supply battery capacity is usually constant, typically available for several years, and when the energy is exhausted, it needs to be replaced surgically). In order to extend the lifetime of such smart sensing devices, wireless chargeable sensors have been widely implanted in smart sensing devices. Thus, such smart aware devices may obtain power through wireless energy harvesting. In a smart city, the smart sensor devices can be wirelessly powered by a mobile charging vehicle as an energy emitter, but it is still difficult to cover all the smart sensor devices, and traffic jam is easily caused. In a traditional wireless power supply cellular network, a dedicated power beacon is usually deployed to provide energy supplement for a rechargeable wireless device, but to achieve high charging efficiency, it is necessary to ensure that a short distance is always kept between a smart sensing device and a charging source in a charging process. Obviously, most smart aware devices do not have such a condition.
In the intelligent sensing equipment network, if the energy of the equipment is insufficient, serious events such as data transmission delay and interruption of the network can occur, and the data transmission capability of the intelligent sensing equipment network is seriously influenced, so that the development and the application of the intelligent sensing equipment network are restricted.
Disclosure of Invention
The invention aims to provide a globally optimal method for prolonging the service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation, which is high in reliability.
The invention provides a method for prolonging the service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation, which comprises the following steps:
s1, establishing an intelligent sensing equipment network model: the intelligent sensing system comprises a cellular base station, a plurality of intelligent terminals with sufficient energy, and a plurality of intelligent sensing devices with limited energy, wherein each intelligent sensing device is connected with each intelligent terminal with sufficient energy; the intelligent terminal with sufficient energy is used for charging the connected intelligent sensing equipment with limited energy, acquiring data uploaded by the connected intelligent sensing equipment with limited energy, forwarding the data to the cellular base station and directly sending the data to the cellular base station; the energy-limited intelligent sensing equipment receives the charging energy of the intelligent terminal with sufficient energy and directly transmits data to the cellular base station or transmits data to the intelligent terminal with sufficient energy; aiming at a plurality of energy-limited intelligent sensing devices connected with each intelligent terminal with sufficient energy, the intelligent sensing devices are divided into an inner circle group intelligent sensing device and an outer circle group intelligent sensing device; the intelligent terminal with sufficient energy is defined as the intelligent terminal with the residual energy accounting for more than 80% of the total energy; the energy-limited intelligent sensing equipment is defined as intelligent sensing equipment which senses surrounding data by using a wireless chargeable sensor in an intelligent sensing equipment network and has residual energy accounting for less than 50% of the total energy; each intelligent terminal with sufficient energy calculates the channel gain between the intelligent terminal with sufficient energy and a plurality of connected intelligent sensing devices with limited energy, and sequences the intelligent sensing devices according to a decreasing rule, wherein the intelligent sensing devices with limited energy corresponding to the sequenced channel gains of the first 50% are defined as the intelligent sensing devices in the inner group; the intelligent sensing equipment with the sequenced channel gain being 50% of the last and corresponding energy being limited is defined as the sensing equipment of the outer group;
s2, each intelligent terminal with sufficient energy initializes the power division and time slot division of the intelligent terminal, calculates the data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the initialized power division and time slot division, and reports the data transmission quantity to the cellular base station;
s3, the cellular base station counts the data transmission quantity reported by all the intelligent terminals with sufficient energy, calculates the frequency band share of each intelligent terminal with sufficient energy, and sends the calculation result to each intelligent terminal with sufficient energy;
s4, each intelligent terminal with sufficient energy calculates power division and time slot division which maximize self utility (namely transmission quantity of self data) according to a frequency band share result fed back by the cellular base station, calculates data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the power division and time slot division result and reports the data transmission quantity to the cellular base station;
s5, repeating the steps S3-S4 until the data transmission quantity of the intelligent sensing equipment with limited energy forwarded by all intelligent terminals with sufficient energy is maximum;
and S6, the intelligent sensing equipment network transmits data according to the optimal result obtained in the step S5.
The power division in step S2 is specifically to divide data transmission power and charging power: the charging power is the charging power for the intelligent terminal with sufficient energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission power is the data transmission power for the intelligent terminal with sufficient energy to transmit data to the cellular network; the time slots are divided into two types: one is time slot division between an intelligent terminal with sufficient energy and an intelligent sensing device with limited energy, specifically divided into a charging time slot and a data transmission time slot: the charging time slot is the charging time length for the intelligent terminal with sufficient energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission time slot is the time length for the intelligent sensing equipment with limited energy to transmit data to the intelligent terminal with sufficient energy; the other type is time slot division between the intelligent terminal with sufficient energy and the cellular base station, and particularly, the time slot is divided into a time slot for forwarding data of others and a time slot for sending data of itself.
Step S2, calculating the data transmission amount forwarded by the intelligent sensing device whose energy is limited, specifically, calculating the data transmission amount by the following steps:
A. calculating the forwarding data volume of the inner circle group by adopting the following formula
Wherein the number of the intelligent terminal with sufficient energy is j, the number of the intelligent sensing equipment of the inner group is i 'and is k in total, the number of the intelligent sensing equipment of the outer group is i' and is n-k in total,
forwarding data volume for inner ring group, bj←i'(τ ') is the amount of data sent by the inner group of intelligent sensing devices i' to the intelligent terminal j with sufficient energy, and
wherein T' is the time slot length available to the inner array of smart sensors within a unit time interval T and
eta is the ratio, tau, divided into inner group users in the optimal charging time slot0For an optimal charging time slot, T is a unit time interval, k is the number of inner circle group intelligent sensing devices connected with the intelligent terminal j with sufficient energy, n is the number of all intelligent sensing devices connected with the intelligent terminal j with sufficient energy, and the time slot is divided into tau ═ tau'0,τ'1,...,τ'k]，τ'0T ' is a charging time slot length, tau ', provided by the intelligent terminal with sufficient energy for the intelligent perception device of the inner ring group 'i'T 'is the data transmission time slot length of the intelligent sensing equipment i' in the inner ring group, H is the communication bandwidth when the intelligent sensing equipment with limited energy sends sensing data to the intelligent terminal with sufficient energy, rho is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi',jThe channel gain between the intelligent sensing equipment i' of the inner ring group and the intelligent terminal j with sufficient energy is obtained; the channel gain is calculated by
di,jIs a straight line between a sending end i and a receiving end jDistance, GtFor transmit end antenna gain, GrFor the receiving end antenna gain, λ is the wavelength of the carrier signal, L is the system loss factor independent of propagation, dcrossoverIs a cross distance, htIs the transmitting end antenna height, hrIs the receiving end antenna height; sigmajThe channel noise power around the intelligent terminal j with sufficient energy;
B. calculating the straight hair data volume of the outer ring group by adopting the following formula
The numbers of the intelligent sensing equipment of the middle and outer ring groups are i', bs←i″(τ ') is the amount of data that outer cluster of smart sensor devices i' send directly to cellular base station s and
b is communication bandwidth when the energy-limited intelligent sensing equipment directly transmits data to the cellular base station, gi″,jIs the channel gain g between the outer group of intelligent sensing equipment i' and the intelligent terminal j with sufficient energys,i″For the channel gain, σ, between the outer cluster of smart sensors i' and the cell sitesIs the channel noise power around the cellular base station;
C. calculating the forwarding data quantity of the outer ring group by adopting the following formula
In the formula bj←i″(tau ') is the data quantity sent by the intelligent sensing equipment i' of the outer ring group to the intelligent terminal j with sufficient energy, and
t' is a unit time interval T, the length of the available time slot of the inner and outer circle group intelligent sensing equipment and
the slot division is τ ″ [ τ ″ ]0,τ″1,...,τ″n-k]，τ″0T 'is the charging time slot length, tau', for providing wireless charging for the intelligent terminal with sufficient energyi″T 'is the data transmission time slot length of the energy-limited intelligent sensing equipment i' of the outer ring group for transmitting data to the intelligent terminal with sufficient energy; gi″,jThe channel gain between the outer group of intelligent sensing equipment i' and the intelligent terminal j with sufficient energy is obtained;
D. the straight-hair data volume of the inner circle group is calculated by adopting the following formula
In the formula bs←i'(τ ") is the amount of data that inner group of smart aware devices i' send directly to the cellular base station and
E. And D, summing the inner ring group forwarding data volume obtained in the step A, the outer ring group straight-hair data volume obtained in the step B, the outer ring group forwarding data volume obtained in the step C and the inner ring group straight-hair data volume obtained in the step D, and thus obtaining the data transmission volume.
The method for calculating the data transmission quantity specifically comprises the following steps of:
a. the data forwarding power of the intelligent terminal j with sufficient energy is set to
The number of the connected intelligent sensing devices with limited energy is n, and an initial value of a variable x is set;
b. obtaining overall optimal slot partitioning
c. Dividing all n intelligent sensing devices with limited energy connected with the intelligent terminal j with sufficient energy into an outer group of intelligent sensing devices and an inner group of intelligent sensing devices;
d. calculating the length T 'of the available time slot of the inner circle group of intelligent sensing equipment and the length T' of the available time slot of the outer circle group in a unit time interval T;
e. setting the value of x as k and calculating the division result of the available time slot of the inner group of intelligent sensing equipment, and simultaneously setting the value of x as n-k and calculating the division result of the available time slot of the outer group of intelligent sensing equipment;
f. calculating inner ring group forwarding data volume
Outer lane group hair straightening data volume
Outer ring group forwarding data volume
And inner circle group hair straightening data volume
And directly summing to obtain the final data transmission quantity.
Calculating the time slot division result in the step e, specifically, calculating the division result by adopting the following steps:
(1) set variable i and assign 1, set variable AjAnd is initialized to 0;
(2) judging the value of the variable i and the value of x:
if i is less than or equal to x, entering the step (3);
if i is larger than x, entering the step (4);
(3) using a formula
To obtain thetai,jAnd A isjAnd thetai,jThe sum is assigned ajAnd let z bejAfter adding 1, repeating the step (2); where p is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi,jChannel gain, σ, of a communication link from an energy-limited smart-aware device i to a sufficiently energetic smart terminal jjThe channel noise power around the intelligent terminal j with sufficient energy;
(4) solving equations
Thereby obtaining
(5) Using formula
Is calculated to obtain
Thereby obtaining the final time slot division result.
Solving equation in step (4)
Thereby obtaining
Specifically, the method comprises the following steps of calculation
1) Setting variable zjAnd is initialized to 1;
2) according to the equation zj·lnzj-zjSolving corresponding A when +1 ═ A;
3) decision A, AjAnd AjThe relationship between the difference between the two and the set first threshold epsilon:
if A < AjAnd A isj-A > ε, then zjAdding 1 to the product and returning to the step 2);
if A > AjAnd A-AjIf epsilon is greater, then the variable max is used to save the upper bound as zjThe lower bound is z, saved by variable minj-1, go to step 4);
otherwise, go to step 6)
4) Judging the difference between max and min and a set second threshold value epsilon2The relationship of (1):
if | max-min | > ε2Entering step 5);
otherwise, entering step 6);
5) will be provided with
Is assigned to zjAnd according to equation zj·lnzj-zjSolving for the value of a and making a decision:
if A > AjThen max is updated to zjAnd returning to the step 4);
otherwise, update min to zjAnd returning to the step 4);
6) will zjIs assigned a value of
Thereby obtaining the final calculation result
Step S3, calculating the frequency band share of each intelligent terminal with sufficient energy, specifically, calculating the frequency band share of each intelligent terminal with sufficient energy by using the following equation:
in the formula
The data transmission power of the intelligent terminal j with sufficient energy,
the charging power of the intelligent terminal j with sufficient energy,
is the maximum transmitting power, alpha, of the intelligent terminal j with sufficient energyjThe time slot length, xi, used for sending the self data when the intelligent terminal j with sufficient energy sends the data to the cellular base stationjThe frequency band resource share obtained for the intelligent terminal j with sufficient energy, W is the total frequency band share, xi, provided by the cellular base station for all the intelligent terminals with sufficient energyjW is the frequency band share of the intelligent terminal j with sufficient energy; g is a radical of formulaj,sThe channel gain between the intelligent terminal j and the cellular base station is sufficient; sigmasIs the channel noise power around the cellular base station;
the amount of data is forwarded for the inner group,
the outer ring group is the amount of the straight-hair data,
the amount of data is forwarded for the outer group,
and phi is a set constant, and is the straight data quantity of the inner circle group.
The step S4 is to calculate the power division and the time slot division for maximizing the self-utility (i.e. the transmission amount of the self-data), specifically, the optimal power division and time slot division are calculated by the following steps:
1. transmitting data with power
Is initialized to
Time alpha for transmitting data of intelligent terminal j with sufficient energy in unit timejInitialization is 0.5;
2. calculating the final data forwarding amount of the intelligent terminal j with sufficient energy;
3. reporting the final data forwarding amount obtained in the step (2) to a cellular base station;
4. for a smart terminal j with sufficient energy:
if receiving the message which is sent by the cellular base station and comprises the data forwarding amounts of all intelligent terminals with sufficient energy, entering the step 5;
if receiving the end packet sent by the cellular base station, entering step 15;
5. setting and initializing variables max1 and min 1; the variable max1 is used to preserve the upper bound of the data transmission power of the smart terminal j with sufficient energy and is initialized to
The variable min1 is used for saving the lower bound of the data transmission power of the intelligent terminal j with sufficient energy and is initialized to 0;
6. judging the absolute value of the difference between max1 and min1 and the set third threshold value epsilon3The relationship of (1):
if | max1-min1| > ε3Entering step 7;
otherwise, go to step 9;
7. will be provided with
Is set to
Calculating the utility value of the intelligent terminal j with sufficient energy;
8. according to the utility calculation formula of the intelligent terminal j with sufficient energy, calculating
And
and a comparison is made:
if AA > BB, then
Assigns max1 and returns to step 6;
otherwise, it will
Assigns min1 and returns to step 6;
9. will be alphajInitializing to 1;
10. the following equations are judged:
if the formula is true, go to step 12; if the calculation formula is not satisfied, go to step 11;
11. will be alphajMinus 0.1 and return to step 10;
12. variables max2 and min2 are set, and max2 is set to αj+0.1，min2＝αj；
13. The absolute value of the difference between max2 and min2 is judged to be equal to the fourth threshold epsilon4The relationship of (1):
if | max2-min2| > ε4Then go to step 14;
otherwise, returning to the step 3;
14. will be provided with
Assigned to alphajAnd judging the following formula:
if the equation holds, min2 is assigned to αj；
If the calculation is not true, max2 is assigned to αjAnd returning to step 13;
15. if an end packet is received from the cellular base station, the algorithm is stopped.
The method for prolonging the service life of the energy-limited intelligent sensing equipment based on the radio frequency energy compensation can reasonably divide power and time slots for each intelligent terminal with sufficient energy, so that each intelligent terminal with sufficient energy can obtain a corresponding frequency spectrum share, the intelligent sensing equipment with limited energy can transmit sensing data by using the energy received from the intelligent terminal with sufficient energy as much as possible, the energy of the intelligent sensing equipment is saved, and the aim of prolonging the whole service life of the intelligent sensing equipment is fulfilled finally.
Drawings
FIG. 1 is a schematic process flow diagram of the process of the present invention.
Fig. 2 is a schematic diagram illustrating a trend of a minimum/maximum life-span improvement degree of a device according to various aspects of the present invention according to a number of smart sensing devices in a fixed area.
Fig. 3 is a diagram illustrating the trend of the minimum/maximum lifetime enhancement degree of different schemes according to the embodiment of the present invention along with the variation of the channel noise power in the fixed area.
Detailed Description
FIG. 1 is a schematic flow chart of the method of the present invention: the invention provides a method for prolonging the service life of energy-limited intelligent sensing equipment based on radio frequency energy compensation, which comprises the following steps:
s1, establishing an intelligent sensing equipment network model: the intelligent sensing system comprises a cellular base station, a plurality of intelligent terminals with sufficient energy and a plurality of intelligent sensing devices with limited energy, wherein the intelligent sensing devices are connected with each intelligent terminal with sufficient energy; the intelligent terminal with sufficient energy is used for charging the connected intelligent sensing equipment with limited energy, acquiring data uploaded by the connected intelligent sensing equipment with limited energy, forwarding the data to the cellular base station and directly sending the data to the cellular base station; the energy-limited intelligent sensing equipment receives the charging energy of the intelligent terminal with sufficient energy and directly transmits data to the cellular base station or transmits data to the intelligent terminal with sufficient energy; aiming at a plurality of energy-limited intelligent sensing devices connected with each intelligent terminal with sufficient energy, the intelligent sensing devices are divided into an inner circle group intelligent sensing device and an outer circle group intelligent sensing device; the intelligent terminal with sufficient energy is defined as the intelligent terminal with the residual energy accounting for more than 80% of the total energy; the energy-limited intelligent sensing equipment is defined as intelligent sensing equipment which senses surrounding data by using a wireless chargeable sensor in an intelligent sensing equipment network and has residual energy accounting for less than 50% of the total energy; each intelligent terminal with sufficient energy calculates the channel gain between the intelligent terminal and the connected intelligent sensing equipment with limited energy, and sorts the channel gains according to a decreasing rule, and the intelligent sensing equipment with limited energy corresponding to the sorted channel gain of the first 50 percent is defined as the intelligent sensing equipment of the inner ring group; the intelligent sensing equipment with the sequenced channel gain being 50% of the last and corresponding energy being limited is defined as the sensing equipment of the outer group;
s2, each intelligent terminal with sufficient energy initializes the power division and time slot division of the intelligent terminal, calculates the data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the initialized power division and time slot division, and reports the data transmission quantity to the cellular base station;
the power division is specifically to divide data transmission power and charging power: the charging power is the charging power for the intelligent terminal with sufficient energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission power is the data transmission power for the intelligent terminal with sufficient energy to transmit data to the cellular network; the time slots are divided into two types: one type is time slot division between an intelligent terminal with sufficient energy and an intelligent sensing device with limited energy, specifically, charging time slots and data transmission time slots are divided: the charging time slot is the charging time length for the intelligent sensing equipment with limited energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission time slot is the time length for the intelligent sensing equipment with limited energy to transmit data to the intelligent terminal with sufficient energy; the other is time slot division between the intelligent terminal with sufficient energy and the cellular base station, which is divided into time slot for forwarding other data and time slot for sending self data
Calculating the data transmission quantity forwarded by the intelligent sensing equipment with limited energy, specifically calculating the data transmission quantity by adopting the following steps:
wherein the number of the intelligent terminal with sufficient energy is j, the number of the intelligent sensing equipment in the inner group is i 'and k in total, the number of the intelligent sensing equipment in the outer group is i' and n-k in total,
forwarding data volume for inner ring group, bj←i'(τ ') is the amount of data sent by the inner group of intelligent sensing devices i' to the intelligent terminal j with sufficient energy, and
wherein T' is the time slot length available to the inner array of smart sensors within a unit time interval T and
eta is the ratio, tau, divided into inner group users in the optimal charging time slot0For an optimal charging time slot, T is a unit time interval, k is the number of inner circle group intelligent sensing devices connected with the intelligent terminal j with sufficient energy, n is the number of all intelligent sensing devices connected with the intelligent terminal j with sufficient energy, and the time slot is divided into tau ═ tau'0,τ'1,...,τ'k]，τ'0T ' is a charging time slot length, tau ', provided by the intelligent terminal with sufficient energy for the intelligent perception device of the inner ring group 'i'T 'is the data transmission time slot length of the inner group of intelligent sensing devices i', and H is the energy from the energy-limited intelligent sensing device to the connectionSufficient communication bandwidth when the intelligent terminal sends the sensing data, rho is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi',jThe channel gain between the intelligent sensing equipment i' of the inner ring group and the intelligent terminal j with sufficient energy is obtained; the channel gain is calculated by
di,jIs the linear distance, G, between the sender i and the receiver jtFor transmit end antenna gain, GrFor the receiving end antenna gain, λ is the wavelength of the carrier signal, L is the propagation independent system loss factor, dcrossoverFor the cross-distance (see the paper WB Heinzelman, Application-specific protocol architecture for wireless networks, Ph. D. Thesis, Massachusetts Institute of Technology (2000)), htIs the transmitting end antenna height, hrIs the receiving end antenna height; sigmajThe channel noise power around the intelligent terminal j with sufficient energy (can be-60 millidecibels/megahertz);
B. calculating the straight hair data volume of the outer ring group by adopting the following formula
The numbers of the intelligent sensing equipment of the middle and outer circle groups are i', bs←i″(τ ') is the amount of data that outer cluster of smart sensor devices i' send directly to cellular base station s and
b is communication bandwidth when the energy-limited intelligent sensing equipment directly transmits data to the cellular base station, gi″,jIntelligent terminal for outer ring group intelligent sensing equipment i' and sufficient energyChannel gain between j, gs,i″For the channel gain, σ, between the outer cluster of smart sensors i' and the cell sitesThe channel noise power around the cellular base station (which may take the value of-60 dbm/mhz);
C. calculating the forwarding data quantity of the outer ring group by adopting the following formula
In the formula bj←i″(tau ') is the data quantity sent by the intelligent sensing equipment i' of the outer ring group to the intelligent terminal j with sufficient energy, and
t' is a unit time interval T, the length of the available time slot of the inner and outer circle group intelligent sensing equipment and
the slot division is τ ″ [ τ ″ ]0,τ″1,...,τ″n-k]，τ″0T' is the charging time slot length for providing wireless charging for the intelligent terminal with sufficient energy; g ″)i,jThe channel gain between the outer group of intelligent sensing equipment i' and the intelligent terminal j with sufficient energy is obtained;
D. the straight-hair data volume of the inner circle group is calculated by adopting the following formula
In the formula bs←i'(τ ") is the amount of data that inner group smart aware device i' sends directly to the cellular base station and
E. summing the inner ring group forwarding data volume obtained in the step A, the outer ring group straight-hair data volume obtained in the step B, the outer ring group forwarding data volume obtained in the step C and the inner ring group straight-hair data volume obtained in the step D to obtain data transmission volume;
the above calculating the data forwarding amount specifically includes the following steps:
a. the data transmission power of the intelligent terminal j with sufficient energy is set to
The number of the connected intelligent sensing devices with limited energy is n, and an initial value of a variable x is set;
b. obtaining overall optimal slot partitioning
c. Dividing all n intelligent sensing devices with limited energy connected with the intelligent terminal j with sufficient energy into an outer group of intelligent sensing devices and an inner group of intelligent sensing devices;
d. calculating the available time slot length T 'of the inner circle group of intelligent sensing equipment and the available time slot length T' of the outer circle group in a unit time interval T;
e. setting the value of x as k and calculating the division result of the available time slot of the inner group of intelligent sensing equipment, and simultaneously setting the value of x as n-k and calculating the division result of the available time slot of the outer group of intelligent sensing equipment; specifically, the following steps are adopted to calculate the division result:
(1) set variable i and assign 1, set variable AjAnd is initialized to 0;
(2) judging the value of the variable i and the value of x:
if i is less than or equal to x, entering the step (3);
if i is larger than x, entering the step (4);
(3) using a formula
To obtain thetai,jAnd A isjAnd thetai,jThe sum is assigned ajZ is a combination ofjAfter adding 1, repeating the step (2); where p is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi,jChannel gain, σ, of a communication link from an energy-limited smart-aware device i to a sufficiently energetic smart terminal jjThe noise power of the surrounding channel of the intelligent terminal j with sufficient energy;
(4) solving equations
Thereby obtaining
Calculated by adopting the following steps
1) Setting variable zjAnd is initialized to 1;
2) according to the equation zj·lnzj-zjSolving corresponding A when the +1 is equal to A;
3) decision A, AjAnd AjThe relationship between the difference and a set first threshold value epsilon (which may be 0.0001) is as follows:
if A < AjAnd A isj-A > ε, then zjAdding 1 to the product and returning to the step 2);
if A > AjAnd A-AjIf epsilon is greater, then the variable max is used to save the upper bound as zjThe lower bound is z, saved by variable minj-1, go to step 4);
otherwise, go to step 6)
4) Judging the difference between max and min and a set second threshold value epsilon2(can take the value of 0.0001) relationship:
if | max-min | > ε2Entering step 5);
otherwise, entering step 6);
5) will be provided with
Is assigned to zjAnd according to equation zj·lnzj-zjSolving for the value of a and making a decision:
if A > AjThen max is updated to zjAnd returning to the step 4);
otherwise, update min to zjAnd returning to the step 4);
6) will zjIs assigned a value of
Thereby obtaining the final calculation result
(5) Using formula
Is calculated to obtain
Thereby obtaining a final time slot division result;
the above processes are all improvements made on the basis of the "Harvest-the-Transmit" protocol ("Collection-Then-transport" protocol) and the paper JuH, Zhang R.Throughput maximum differentiation in Wireless Power Communication Networks [ J ]. IEEE Transactions on Wireless Communications,2013,13(1): 418-428;
f. calculating inner ring group forwarding data volume
Outer lane group hair straightening data volume
Outer ring group forwarding data volume
And inner circle group hair straightening data volume
And directly summing to obtain the final data transmission quantity
S3, the cellular base station counts the data transmission quantity reported by all the intelligent terminals with sufficient energy, calculates the frequency band share of each intelligent terminal with sufficient energy, and sends the calculation result to each intelligent terminal with sufficient energy; specifically, the frequency band share of the intelligent terminal with sufficient energy is calculated by adopting the following formula:
in the formula
The data transmission power of the intelligent terminal j with sufficient energy,
the charging power of the intelligent terminal j with sufficient energy,
is the maximum transmitting power, alpha, of the intelligent terminal j with sufficient energyjThe time slot length, xi, used for sending the self data when the intelligent terminal j with sufficient energy sends the data to the cellular base stationjThe frequency band resource share obtained for the intelligent terminal j with sufficient energy, W is the total frequency band share, xi, provided by the cellular base station for all the intelligent terminals with sufficient energyjW is the frequency band share of the intelligent terminal j with sufficient energy; gj,sThe channel gain between the intelligent terminal j and the cellular base station with sufficient energy is obtained; sigmasIs the channel noise power around the cellular base station;
the amount of data is forwarded for the inner group,
the outer ring group is the amount of the straight-hair data,
the amount of data is forwarded for the outer group,
the data volume is directly sent for the inner circle group, and phi is a set constant;
s4, each intelligent terminal with sufficient energy calculates power division and time slot division which maximize self utility (namely transmission quantity of self data) according to a frequency band share result fed back by the cellular base station, calculates data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the power division and time slot division result and reports the data transmission quantity to the cellular base station; specifically, the optimal power division and time slot division are calculated by adopting the following steps:
1. transmitting data with power
Is initialized to
Time alpha for transmitting data of intelligent terminal j with sufficient energy in unit timejInitialization is 0.5;
2. calculating the final data forwarding amount of the intelligent terminal j with sufficient energy;
3. reporting the final data forwarding amount obtained in the step (2) to a cellular base station;
4. for a smart terminal j with sufficient energy:
if receiving the message which is sent by the cellular base station and comprises the data forwarding amounts of all intelligent terminals with sufficient energy, entering the step 5;
if receiving the end packet sent by the cellular base station, entering step 15;
5. setting and initializing variables max1 and min 1; the variable max1 is used to preserve the upper bound of the data transmission power of the smart terminal j with sufficient energy and is initialized to
The variable min1 is used for saving the lower bound of the data transmission power of the intelligent terminal j with sufficient energy and is initialized to 0;
6. judging the absolute value of the difference value between max1 and min1 and the set third threshold value epsilon3(can take the value of 0.0001) relationship:
if | max1-min1| > ε3Entering step 7;
otherwise, go to step 9;
7. will be provided with
Is set to
Calculating the utility value of the intelligent terminal j with sufficient energy;
8. according to the utility calculation formula of the intelligent terminal j with sufficient energy, calculating
And
and a comparison is made:
if AA > BB, then
Assigns max1 and returns to step 6;
otherwise, it will
Assigns min1 and returns to step 6;
9. will be alphajInitializing to 1;
10. the following equations are judged:
if the calculation formula is established, go to step 12; if the calculation formula is not satisfied, go to step 11;
11. will be alphajMinus 0.1 and return to step 10;
12. variables max2 and min2 are set, and max2 is set to αj+0.1，min2＝αj；
13. The absolute value of the difference between max2 and min2 is judged to be equal to the fourth threshold epsilon4(may take a value of 0.0001) relationship:
if | max2-min2| > ε4Then go to step 14;
otherwise, returning to the step 3;
14. will be provided with
Assigned to alphajAnd judging the following formula:
if the equation holds, min2 is assigned to αj；
If the calculation is not true, max2 is assigned to αjAnd returning to step 13;
15. stopping the algorithm if an end packet is received from the cellular base station;
s5, repeating the steps S3-S4 until the data transmission quantity of the intelligent sensing equipment with limited energy forwarded by all intelligent terminals with sufficient energy is maximum;
and S6, the intelligent sensing equipment network transmits data according to the optimal result obtained in the step S5.
The process of the invention is further illustrated below with reference to one example:
the microcellular network has a radius of 100 m and is formed by a network which is arranged in the center of the areaThe system comprises a cellular network and a group of intelligent nodes (including intelligent sensing equipment and intelligent terminals). For simplicity and without loss of generality, we assume that six intelligent terminals equally spaced from the cellular network and evenly distributed on a circle with a radius of 40 meters are selected to serve as energy-rich intelligent terminals, and each energy-rich intelligent terminal selects an energy-limited intelligent sensing device in a coverage area to provide wireless charging service and data forwarding service for the intelligent terminal. In this embodiment, unless otherwise specified, the number Ω of the energy-limited smart sensing devices isiThe value is 1000, and the variation range is 600-1200; if not specially stated, the value of the channel noise power is-60 millidecibels/megahertz, and the variation range is-120 to-50 millidecibels/megahertz. The simulation parameters are shown in table 1.
TABLE 1 simulation parameter schematic table
The results shown in fig. 2 to 3 were obtained using an OMNeT + +4.6 network simulator. Wherein scheme 1 is the process of this patent; scheme 2 is a throughput sum Maximization scheme in the document (JuH, Zhang R.Throughput Maximization in Wireless Power Communication Networks [ J ]. IEEE Transactions on Wireless Communications,2013,13(1): 418-428).
From fig. 2, it can be seen that, as the number of the smart sensing devices in the fixed area increases, the minimum lifetime promotion degrees in the schemes 1 and 2 both decrease, when the number of the smart sensing devices in the fixed area is small, the minimum lifetime promotion degree in the scheme 1 is still lower than that in the scheme 2, until after a threshold value is exceeded, the minimum lifetime promotion degree in the scheme 1 is always higher than that in the scheme 2; the maximum life span improvement degrees of the scheme 1 and the scheme 2 both show an increasing trend, and the maximum life span improvement degree of the scheme 1 is always lower than that of the scheme 2. This shows that the scheme that this patent proposed is in the volatility of life-span promotion degree under the great condition of intelligent perception equipment quantity in fixed area, and each intelligent perception equipment life-span promotion degree is comparatively balanced promptly.
The reason why the minimum life-span improvement degrees in the schemes 1 and 2 are in descending trend along with the increase of the number of the intelligent sensing devices in the fixed area and the maximum life-span improvement degrees are in ascending trend is that: as the number of smart aware devices in a fixed area increases, the number of energy-constrained smart aware devices associated with energy-rich smart devices may also present an increasing trend. For a certain smart device with sufficient energy, as the number of smart sensing devices in a fixed area increases, the location of the newly added associated energy-limited smart sensing device is random, and three situations will occur: 1. a certain newly added associated device becomes an associated device farthest from the intelligent device with sufficient energy; 2. a newly added associated device becomes the closest associated device to the intelligent device with sufficient energy; 3. the newly added associated device is neither the closest device nor the farthest device from the smart device with sufficient energy. When the case 1 occurs, the minimum data transmission time slot divided by the smart device with sufficient energy must be reduced, and thus the minimum life span improvement degree in the case 1 and the case 2 is reduced. When the situation 2 occurs, the maximum data transmission slots divided by the smart device with sufficient energy must be increased, and thus the maximum lifetime improvement degree in the schemes 1 and 2 is increased. When scenario 3 occurs, the minimum/maximum life boost level remains substantially unchanged. Therefore, overall, as the number of the smart sensor devices in the fixed area increases, the minimum life span improvement degrees of the scheme 1 and the scheme 2 are in a decreasing trend, and the maximum life span improvement degrees of the scheme 1 and the scheme 2 are in an increasing trend.
The reason why the maximum life span improvement degree of the scheme 1 is always lower than that of the scheme 2 is that: when the same number of energy-limited intelligent sensing devices are arranged in a fixed area, the number and the positions of energy-limited intelligent terminals associated with a certain intelligent device with sufficient energy are completely the same, when the scheme 1 provided by the patent is adopted, in order to meet the requirement that the energy-limited intelligent sensing device transmits sensing data with basic length, for the energy-limited intelligent sensing device with the maximum channel gain of the intelligent device with sufficient energy in a group of associated energy-limited intelligent sensing devices, fewer transmission time slots are obtained in a unit time compared with the scheme 2, so that the amount of sensing data transmitted to the intelligent device with sufficient energy by the device is reduced, and the maximum life-span improvement degree of the scheme 1 is lower than the maximum life-span improvement degree of the scheme 2.
When the number of the intelligent sensing devices in the fixed area is small, the minimum life-span improvement degree of the scheme 1 is still lower than that of the scheme 2, and the reason why the minimum life-span improvement degree of the scheme 1 is always higher than that of the scheme 2 is that: when the number of the intelligent sensing devices in the fixed area is small, the number of the energy-limited intelligent sensing devices associated with the intelligent devices with sufficient energy is small, and the data transmission time slots obtained by the device with the minimum channel gain by adopting the scheme 1 and the scheme 2 are not greatly different. Part of the energy collected by the energy-limited smart aware devices associated with scheme 1 is used to transmit data directly to the cellular base station, while all of the energy collected by the energy-limited smart terminals in scheme 2 is used to transmit data to the energy-rich smart devices. Because the distance from the energy-limited intelligent sensing equipment to the intelligent equipment with sufficient energy is far less than the distance from the base station, when the same amount of energy is used for sending data to the base station, the data volume of the data directly sent to the base station by the energy-limited intelligent sensing equipment is obviously less than the data volume forwarded by the intelligent equipment with sufficient energy. Therefore, when the number of smart aware devices in a fixed area is small, the minimum lifetime improvement degree of scheme 1 is still lower than that of scheme 2. When the number of the intelligent sensing devices in the fixed area is large, the number of the energy-limited intelligent sensing devices associated with the intelligent devices with sufficient energy is large, the advantage of the scheme 1 in allocating more data transmission time slots to the devices with smaller channel gains is more and more obvious, and the data transmission time slots distributed by the devices with the minimum channel gains in the scheme 1 are far better than that of the scheme 2, so that after the number of the intelligent sensing devices in the fixed area exceeds a threshold value, the minimum service life improvement degree of the scheme 1 is always higher than that of the scheme 2.
From fig. 3, it can be seen that, as the channel noise power in the fixed area increases, the minimum/maximum lifetime improvement degree of the scheme 1 and the minimum/maximum lifetime improvement degree of the scheme 2 both have decreasing trends, and the minimum lifetime improvement degree of the scheme 1 is always higher than the minimum lifetime improvement degree of the scheme 2, but the maximum lifetime improvement degree of the scheme 1 is always lower than the maximum lifetime improvement degree of the scheme 2.
The reason why the minimum/maximum life span improvement degrees of the schemes 1 and 2 are in a decreasing trend with the increase of the channel noise power in the fixed area is that: when the intelligent device with sufficient energy provides wireless charging service for the associated intelligent sensing device with limited energy, the total energy which can be collected by the intelligent sensing device with limited energy only depends on the charging power of the intelligent device with sufficient energy and is unrelated to the environmental noise power, therefore, when the intelligent device with sufficient energy uses the charging power with the same size, the total energy which can be received by the intelligent sensing device with limited energy is not changed, the data transmission power of an uplink cannot be changed, and the data transmission rate of the intelligent sensing device with limited energy to the intelligent device with sufficient energy or a cellular base station is in a descending trend along with the increase of the channel noise power under the same data transmission power; in addition, if a smart device with sufficient energy is transmitting data to a cellular base station using the same amount of data transmission power, the rate is also decreasing. Combining the above two reasons, the minimum/maximum lifetime promotion degrees of both scheme 1 and scheme 2 are in a decreasing trend as the channel noise power in the fixed area increases.
The reason why the minimum life span improvement degree of the scheme 1 is always higher than the minimum life span improvement degree of the scheme 2 and the maximum life span improvement degree is always lower than the maximum life span improvement degree of the scheme 2 is that: the goal of scenario 2 is to achieve throughput sum maximization by allocating more time to the perceiving device that is closer to the smart device where energy is sufficient; the purpose of the scheme 1 is to maximize the benefit of the intelligent sensing device with sufficient energy while satisfying the requirement that the intelligent sensing device with limited energy transmits the sensing data with basic length, which is realized by adopting the intelligent sensing device grouping and time slot improvement scheme based on the Harvest-Then-Transmit protocol. Therefore, for the energy-limited smart sensing device with the minimum channel gain of the smart device with sufficient energy in the set of energy-limited smart sensing devices associated with the smart device with sufficient energy, the scheme 1 provided by the patent may obtain more transmission time slots per unit time than the scheme 2, so as to send more sensing data to the smart device with sufficient energy, and therefore, the minimum lifetime improvement degree of the scheme 1 is always higher than that of the scheme 2. Correspondingly, for the energy-limited intelligent terminal with the maximum channel gain of the intelligent device with sufficient energy in the group of energy-limited intelligent terminals associated with the intelligent device with sufficient energy, the scheme 1 provided by the patent will obtain fewer transmission time slots in a unit time than the scheme 2, so that the amount of sensing data sent to the intelligent device with sufficient energy is reduced, and therefore, the maximum life span improvement degree of the scheme 1 is always lower than that of the scheme 2.
The invention improves the service life of each node in the system and simultaneously maximizes the data transmission efficiency and rate of the whole network.
Claims (7)
1. A service life prolonging method of energy-limited intelligent sensing equipment based on radio frequency energy compensation comprises the following steps:
s1, establishing an intelligent sensing equipment network model: the intelligent sensing system comprises a cellular base station, a plurality of intelligent terminals with sufficient energy and a plurality of intelligent sensing devices with limited energy, wherein the intelligent sensing devices are connected with each intelligent terminal with sufficient energy; the intelligent terminal with sufficient energy is used for charging the connected intelligent sensing equipment with limited energy, acquiring data uploaded by the connected intelligent sensing equipment with limited energy, forwarding the data to the cellular base station and directly sending the data to the cellular base station; the energy-limited intelligent sensing equipment receives the charging energy of the intelligent terminal with sufficient energy and directly transmits data to the cellular base station or transmits data to the intelligent terminal with sufficient energy; aiming at a plurality of energy-limited intelligent sensing devices connected with each intelligent terminal with sufficient energy, the intelligent sensing devices are divided into an inner circle group intelligent sensing device and an outer circle group intelligent sensing device; the intelligent terminal with sufficient energy is defined as the intelligent terminal with the residual energy accounting for more than 80% of the total energy; the energy-limited intelligent sensing equipment is defined as intelligent sensing equipment which senses surrounding data by using a wireless chargeable sensor in an intelligent sensing equipment network and has residual energy accounting for less than 50% of the total energy; each intelligent terminal with sufficient energy calculates the channel gain between the intelligent terminal with sufficient energy and a plurality of connected intelligent sensing devices with limited energy, and sequences the intelligent sensing devices according to a decreasing rule, wherein the intelligent sensing devices with limited energy corresponding to the sequenced channel gains of the first 50% are defined as the intelligent sensing devices in the inner group; the intelligent sensing equipment with the sequenced channel gain being 50% of the last and corresponding energy being limited is defined as the sensing equipment of the outer group;
s2, each intelligent terminal with sufficient energy initializes power division and time slot division of the intelligent terminal, calculates data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the initialized power division and time slot division, and reports the data transmission quantity to a cellular base station;
s3, the cellular base station counts the data transmission quantity reported by all the intelligent terminals with sufficient energy, calculates the frequency band share of each intelligent terminal with sufficient energy, and sends the calculation result to each intelligent terminal with sufficient energy; specifically, the frequency band share of the intelligent terminal with sufficient energy is calculated by adopting the following formula:
in the formula
The data transmission power of the intelligent terminal j with sufficient energy,
the charging power of the intelligent terminal j with sufficient energy,
is the maximum transmitting power, alpha, of the intelligent terminal j with sufficient energyjJ-direction cellular base for intelligent terminal with sufficient energyThe length of the time slot, ξ, used by a station to transmit its own data when it is transmitting datajThe frequency band resource share obtained for the intelligent terminal j with sufficient energy, W is the total frequency band share, xi, provided by the cellular base station for all the intelligent terminals with sufficient energyjW is the frequency band share of the intelligent terminal j with sufficient energy; gj,sThe channel gain between the intelligent terminal j and the cellular base station is sufficient; sigmasIs the channel noise power around the cellular base station;
the amount of data is forwarded for the inner group,
the outer ring group is the amount of the straight-hair data,
the amount of data is forwarded for the outer group,
the data volume is directly sent for the inner circle group, and phi is a set constant;
s4, each intelligent terminal with sufficient energy calculates power division and time slot division which maximize the self utility according to the frequency band share result fed back by the cellular base station, calculates the data transmission quantity forwarded by the intelligent sensing equipment with limited energy according to the power division and time slot division result and reports the data transmission quantity to the cellular base station;
s5, repeating the steps S3-S4 until the data transmission quantity of the intelligent sensing equipment with limited energy forwarded by all intelligent terminals with sufficient energy is maximum;
and S6, the intelligent sensing equipment network transmits data according to the optimal result obtained in the step S5.
2. The method for prolonging the service life of an energy-constrained intelligent sensing device based on radio frequency energy compensation as claimed in claim 1, wherein the power division in step S2 is specifically dividing data transmission power and charging power: the charging power is the charging power for the intelligent terminal with sufficient energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission power is the data transmission power for the intelligent terminal with sufficient energy to transmit data to the cellular network; the time slots are divided into two types: one is time slot division between an intelligent terminal with sufficient energy and an intelligent sensing device with limited energy, specifically divided into a charging time slot and a data transmission time slot: the charging time slot is the charging time length for the intelligent terminal with sufficient energy to charge the connected intelligent sensing equipment with limited energy, and the data transmission time slot is the time length for the intelligent sensing equipment with limited energy to transmit data to the intelligent terminal with sufficient energy; the other type is time slot division between the intelligent terminal with sufficient energy and the cellular base station, and particularly, the time slot is divided into a time slot for forwarding data of others and a time slot for sending data of itself.
3. The method for prolonging the service life of an energy-limited smart sensor device based on radio frequency energy compensation as claimed in claim 2, wherein the step S2 is to calculate the data transmission amount forwarded by the energy-limited smart sensor device, specifically to calculate the data transmission amount by the following steps:
A. calculating the forwarding data volume of the inner circle group by adopting the following formula
Wherein the number of the intelligent terminal with sufficient energy is j, the number of the intelligent sensing equipment of the inner group is i 'and is k in total, the number of the intelligent sensing equipment of the outer group is i' and is n-k in total,
forwarding data volume for inner ring group, bj←i'(τ') Intelligent sensing for inner circle groupThe data volume of i' to the intelligent terminal j with sufficient energy is prepared and
wherein T' is the time slot length available to the inner array of smart sensors within a unit time interval T and
eta is the ratio, tau, divided into inner group users in the optimal charging time slot0For an optimal charging time slot, T is a unit time interval, k is the number of inner circle group intelligent sensing devices connected with the intelligent terminal j with sufficient energy, n is the number of all intelligent sensing devices connected with the intelligent terminal j with sufficient energy, and the time slot is divided into tau ═ tau'0,τ'1,...,τ'k]，τ'0T ' is a charging time slot length, tau ', provided by the intelligent terminal with sufficient energy for the intelligent perception device of the inner ring group 'i’T 'is the data transmission time slot length of the intelligent sensing equipment i' in the inner ring group, H is the communication bandwidth when the intelligent sensing equipment with limited energy sends sensing data to the intelligent terminal with sufficient energy, rho is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi',jThe channel gain between the intelligent sensing equipment i' of the inner ring group and the intelligent terminal j with sufficient energy is obtained; the channel gain is calculated by
di,jIs the linear distance, G, between the sender i and receiver jtFor transmit end antenna gain, GrFor the receiving end antenna gain, λ is the wavelength of the carrier signal, L is the system loss factor independent of propagation, dcrossoverIs a cross distance, htIs the transmitting end antenna height, hrIs the receiving end antenna height; sigmajThe channel noise power around the intelligent terminal j with sufficient energy;
B. the straight hair data volume of the outer ring group is calculated by adopting the following formula
The serial numbers of the intelligent sensing equipment of the outer ring group in the formula are i' and bs←i”(τ ') is the amount of data sent directly by the outer group of smart sensing devices i' to the cellular base station s and
b is the communication bandwidth when the energy-limited intelligent sensing equipment directly transmits data to the cellular base station, gi”,jIs the channel gain g between the outer group of intelligent sensing equipment i' and the intelligent terminal j with sufficient energys,i”Is the channel gain, sigma, between the outer group of smart sensors i' and the cell sitesIs the channel noise power around the cellular base station;
C. calculating the forwarding data quantity of the outer ring group by adopting the following formula
In the formula bj←i”(tau ') is the data volume sent by the intelligent sensing equipment i' of the outer ring group to the intelligent terminal j with sufficient energy, and
t' is the length of the available time slot of the inner and outer ring sets of the intelligent sensing equipment in a unit time interval T and
time slot division τ ═ τ "0,τ”1,...,τ”n-k]，τ”0T 'charging time slot length, τ', for providing wireless charging for intelligent terminal with sufficient energy "i”T 'is the data transmission time slot length of the energy-limited intelligent sensing equipment i' of the outer ring group for transmitting data to the intelligent terminal with sufficient energy; gi”,jThe channel gain between the outer group of intelligent sensing equipment i' and the intelligent terminal j with sufficient energy is obtained;
D. the straight-hair data volume of the inner circle group is calculated by adopting the following formula
In the formula bs←i'(τ ') is the amount of data that inner group of smart aware devices i' send directly to cellular base station and
gs,i'the channel gain between the intelligent sensing equipment i' of the inner circle group and the cellular base station;
E. and D, summing the inner ring group forwarding data volume obtained in the step A, the outer ring group straight-hair data volume obtained in the step B, the outer ring group forwarding data volume obtained in the step C and the inner ring group straight-hair data volume obtained in the step D, and thus obtaining the data transmission volume.
4. The method for prolonging the service life of the energy-limited intelligent sensing device based on the radio frequency energy compensation as claimed in claim 3, wherein the step of calculating the data transmission quantity specifically comprises the following steps:
a. the data forwarding power of the intelligent terminal j with sufficient energy is set to
Energy of connectionThe number of the intelligent sensing equipment with limited quantity is n, and an initial value of a variable x is set;
b. obtaining overall optimal slot partitioning
c. Dividing all n intelligent sensing devices with limited energy connected with the intelligent terminal j with sufficient energy into an outer group of intelligent sensing devices and an inner group of intelligent sensing devices;
d. calculating the available time slot length T' of the inner circle group of intelligent sensing equipment and the available time slot length T of the outer circle group in the unit time interval T;
e. setting the value of x as k and calculating the division result of the available time slot of the inner group of intelligent sensing equipment, and simultaneously setting the value of x as n-k and calculating the division result of the available time slot of the outer group of intelligent sensing equipment;
f. calculating inner ring group forwarding data volume
Outer lane group hair straightening data volume
Outer ring group forwarding data volume
And inner circle group hair straightening data volume
And directly summing to obtain the final data transmission quantity.
5. The method as claimed in claim 4, wherein the step e of calculating the slot partition result specifically comprises the following steps:
(1) set variable i and assign 1, set variable AjAnd is initialized to 0;
(2) judging the value of the variable i and the value of x:
if i is less than or equal to x, entering the step (3);
if i is larger than x, entering the step (4);
(3) using a formula
To obtain
And A isjAnd
after summing, assign ajZ is a combination ofjAfter adding 1, repeating the step (2); where p is an energy conversion efficiency factor,
the charging power g of the intelligent terminal j with sufficient energyi,jChannel gain, σ, of a communication link from an energy-limited smart-aware device i to a sufficiently energetic smart terminal jjThe noise power of the surrounding channel of the intelligent terminal j with sufficient energy;
(4) solving equation
Thereby obtaining
(5) Using formula
Is calculated to obtain
Thereby obtaining the final time slot division result.
6. Root of herbaceous plantThe method for prolonging service life of energy-limited smart sensor based on radio frequency energy compensation as claimed in claim 5, wherein the equation of solution in step (4)
Thereby obtaining
Specifically, the method comprises the following steps of calculation
1) Setting variable zjAnd is initialized to 1;
2) according to the equation zj·lnzj-zjSolving corresponding A when +1 ═ A;
3) decision A, AjAnd AjThe relationship between the difference between and the set first threshold epsilon:
if A < AjAnd A isj-A > ε, then zjAdding 1 to the product and returning to the step 2);
if A > AjAnd A-AjIf epsilon is greater, then the variable max is used to save the upper bound as zjThe lower bound is z, saved by variable minj-1, go to step 4);
otherwise, go to step 6)
4) Judging the difference between max and min and a set second threshold value epsilon2The relationship of (1):
if | max-min | > ε2Entering step 5);
otherwise, entering step 6);
5) will be provided with
Is assigned to zjAnd according to equation zj·ln zj-zjSolving for the value of a and making a decision:
if A > AjThen max is updated to zjAnd returning to the step 4);
otherwise, update min to zjAnd returning to the step 4);
6) will zjIs assigned a value of
Thereby obtaining the final calculation result
7. The method of claim 6, wherein the step S4 is performed to calculate the power division and the time slot division for maximizing the utility of the smart sensor, specifically to calculate the optimal power division and time slot division by the following steps:
1. transmitting data with power
Is initialized to
Time alpha for transmitting data of the intelligent terminal j with sufficient energy in unit timejInitialization is 0.5;
2. calculating the final data forwarding amount of the intelligent terminal j with sufficient energy;
3. reporting the final data forwarding amount obtained in the step (2) to a cellular base station;
4. for a smart terminal j with sufficient energy:
if receiving the message which is sent by the cellular base station and comprises the data forwarding amounts of all the intelligent terminals with sufficient energy, entering the step 5;
if receiving the end packet sent by the cellular base station, entering step 15;
5. setting and initializing variables max1 and min 1; the variable max1 is used to preserve the upper bound of the data transmission power of the smart terminal j with sufficient energy and is initialized to
The variable min1 is used for saving the lower bound of the data transmission power of the intelligent terminal j with sufficient energy and is initialized to 0;
6. judging the absolute value of the difference value between max1 and min1 and the set third threshold value epsilon3The relationship of (1):
if | max1-min1| > ε3Entering step 7;
otherwise, go to step 9;
7. will be provided with
Is set to
Calculating the utility value of the intelligent terminal j with sufficient energy;
8. according to the utility calculation formula of the intelligent terminal j with sufficient energy, calculating
And
and a comparison is made:
if AA > BB, then
Assigns max1 and returns to step 6;
otherwise, it will
Assigns min1 and returns to step 6;
9. will alphajInitializing to 1;
10. the following equations are judged:
if the calculation formula is established, go to step 12; if the calculation formula is not satisfied, go to step 11;
11. will be alphajMinus 0.1 and return to step 10;
12. variables max2 and min2 are set, and max2 is set to αj+0.1，min2＝αj；
13. The absolute value of the difference between max2 and min2 is judged to be equal to the fourth threshold epsilon4The relationship of (1):
if | max2-min2| > ε4Then go to step 14;
otherwise, returning to the step 3;
14. will be provided with
Assigned to alphajAnd judging the following formula:
if the equation holds, min2 is assigned to αj；
If the calculation is not true, max2 is assigned to αjAnd returning to step 13;
15. if an end packet is received from the cellular base station, the algorithm is stopped.
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