KR101137729B1 - A method and apparatus for scheduling in multicarrier system considering power amplifier characteristic - Google Patents

Abstract

The present invention relates to an energy efficient uplink resource allocation method and apparatus in consideration of characteristics of a power amplifier in a multi-carrier system. The present invention relates to link scheduling by calculating a transmission time and a number of subcarriers for maximizing energy efficiency in a characteristic of a power amplifier. It relates to a method and apparatus for performing the same.

In an apparatus for scheduling a link to minimize packet transmission energy of a power amplifier in consideration of a multi-carrier system according to the present invention, the scheduling apparatus includes a processor and a memory, wherein the processor includes a maximum value of the information bit transmission time and an information bit transmission time. Set a search region including a minimum value, a maximum value of the number of carriers, and a minimum value of the number of carriers, search for one or more coordinate values that minimize packet transmission energy within the search region, and search based on the retrieved one or more coordinate values Resetting the area, the coordinate values include the information bit transmission time and the number of carriers.

Transmission time, subcarrier, multicarrier, OFDM, scheduling

Description

Scheduling Method and Apparatus Considering Power Amplifier Characteristics in Multi-carrier System {A METHOD AND APPARATUS FOR SCHEDULING IN MULTICARRIER SYSTEM CONSIDERING POWER AMPLIFIER CHARACTERISTIC}

The present invention relates to an energy efficient uplink resource allocation method and apparatus in consideration of the characteristics of a power amplifier in a multi-carrier system. The present invention relates to an uplink by calculating the transmission time and the number of subcarriers for maximizing energy efficiency in the characteristics of a power amplifier. A method and apparatus for performing scheduling.

According to Shannon's capacity theory, the energy consumption, or energy-per-bit, required to transmit a single bit of information is monotonically reduced as the transmission time increases. . Based on this monotonic reduction relationship, previous studies have basically used the lowest bit-order modulation and the lowest coding-rate channel coding to improve the energy efficiency of wireless communications. We propose a scheduling scheme that transmits information bits. Typical examples include lazy scheduling and move right techniques.

However, the correlation between the transmission time and the energy of the information bits is a result obtained without accurate consideration of the power amplifier in the terminal, as shown in FIG. Therefore, based on this correlation, the proposed scheduling technique can produce a completely different result than expected in implementing and applying a communication system. This result was found while overlooking the relationship between the energy consumed by the terminal and the transmitted energy in the process of deriving the existing correlation.

Conventionally, in order to obtain energy consumed by the terminal, the energy received from the DC voltage 103 of the power amplifier is amplified by the signal input through the P _in 101 with a fixed efficiency equal to or smaller than 1. Since it is used to output to the P _tx 105, it is assumed that the amount of DC voltage 103 linearly proportional to the P _tx 105 as the energy consumed by the terminal, based on the information bits as described above. The correlation between the transmission time and the energy is derived.

In fact, the general power amplifier does not have a fixed efficiency when the energy required to amplify the P _in (101) signal is supplied from the DC voltage (103), and the efficiency depends on the size of the P _tx (105). It has variable efficiency. In other words, the amplification efficiency varies according to the range of the signal to be amplified, and also has a characteristic that varies depending on the type of power amplifier. Therefore, the energy DC voltage 103 consumed by the terminal has a variable characteristic according to the size of the P _tx 105 and the type of the power amplifier.

As a result, considering the characteristics of the power amplifier used in the wireless communication module of the equipment, the aforementioned monotonic reduction relationship is no longer valid, and the energy per bit-per-bit is reduced when the transmission time of the information bits becomes longer than a certain threshold. Begins to increase. On the basis of this relationship, the present applicant has proposed modified lazy scheduling and modified move right scheduling.

In addition, the present applicant has proposed an uplink scheduling method and apparatus considering a power amplifier in a mobile communication terminal in Korean Patent Application No. 10-2007-0039257. The method includes calculating a packet transmission time for minimizing energy consumed during packet transmission by using a DC voltage and a nonlinear amplification efficiency used for signal amplification in a power amplifier, and calculating Including the process of scheduling the uplink data by using the packet transmission time, the packet transmission time for maximizing energy efficiency is calculated in consideration of the correlation between the transmission time and the energy of the information bits according to the characteristics of the power amplifier, By performing uplink scheduling by using, a method for reducing the amount of energy consumed in the terminal.

However, many systems currently being developed employ an orthogonal frequency division multiplex (OFDM) scheme to support high transmission efficiency and wide bandwidth, which brings another problem of transmission energy efficiency. In other words, in addition to the problems previously considered, a new power efficiency ratio is generated depending on the transmission bandwidth. In other words, the OFDM scheme divides the entire bandwidth into multiple subbands and uses the divided frequency subbands for parallel data transmission, thereby enabling variable bandwidth allocation for the communication environment of the terminal. Let's do it. This leads to the conclusion that different terminals can be allocated different bandwidths for data transmission and can choose the optimal transmission bandwidth for minimum energy consumption.

For reference, an orthogonal frequency division multiplexed communication system effectively divides the overall system bandwidth into multiple subbands, and these multiple subbands are also called frequency subchannels. Each frequency subchannel is associated with a separate subcarrier (or tone) in which data can be modulated. In an OFDM system, data to be transmitted (ie, information bits) is first encoded in a particular coding scheme to generate coding bits, which are then further grouped into multibit symbols that are then mapped to modulation symbols. Each modulation symbol corresponds to a point in the signal arrangement defined by the particular modulation scheme (eg, M-PSK or M-QAM) used for the transmission data. A modulation symbol may be transmitted on each frequency subchannel at every time interval that may depend on the bandwidth of each frequency subchannel. OFDM can be used to eliminate inter-symbol interference (ISI) caused by frequency selective fading, which is characterized by different amounts of attenuation across the system bandwidth. Thus, multicarrier systems such as OFDM are increasingly being employed in communication systems.

An object of the present invention is to perform scheduling of a communication link by calculating the number of subcarriers that maximize energy efficiency in consideration of characteristics of a power amplifier in a multicarrier system. In addition, an object of the present invention is to perform scheduling by simultaneously calculating the transmission time of information bits maximizing energy efficiency and the number of subcarriers in consideration of characteristics of a power amplifier.

In a multi-carrier communication system according to the present invention, a method for scheduling a link includes: obtaining a number of carriers capable of minimizing packet transmission energy of a power amplifier; And scheduling the link based on the estimated number of carriers.

The method of scheduling a link further includes obtaining an information bit transmission time that can minimize the packet transmission energy of the power amplifier, and the scheduling of the link may comprise: linking the link based on the estimated number of carriers and the information bit transmission time. It is desirable to include the step of scheduling.

In the multi-carrier communication system according to the present invention, a method for minimizing packet transmission energy of a power amplifier includes a maximum value of an information bit transmission time, a minimum value of an information bit transmission time, a maximum value of the number of carriers, and a minimum value of the number of carriers. Setting a search area; Searching for one or more coordinate values that minimize packet transmission energy within the search area; And resetting the search region based on the retrieved one or more coordinate values, wherein the coordinate values include information bit transmission time and the number of carriers.

In a method of minimizing packet transmission energy of a power amplifier, retrieving one or more coordinate values and resetting the search region are performed repeatedly until the search region converges, and information bits are transmitted when the search region converges. Preferably, the method further comprises the step of scheduling the power amplifier in time and number of carriers.

In a method of minimizing packet transmission energy of a power amplifier, setting the search region comprises: setting a predetermined initial information bit transmission time to a minimum value of the information bit transmission time of the search region; Setting a predetermined number of initial carriers to a minimum value of the number of carriers in the search area; Searching for the number of carriers capable of minimizing packet transmission energy of the power amplifier at a minimum value of the information bit transmission time of the search region and setting the maximum number of carriers in the search region; And searching for an information bit transmission time for minimizing the packet transmission energy of the power amplifier at a minimum value of the number of carriers in the search region and setting the maximum value of the information bit transmission time in the search region.

In a method of minimizing packet transmission energy of a power amplifier, retrieving one or more coordinate values comprises: selecting a first information bit transmission time between a maximum value and a minimum value of information bit transmission times of a search region; Selecting the number of first carriers between the maximum value of the number of carriers and the maximum value of the number of carriers in the search area; Retrieving the number of second carriers for minimizing packet transmission energy in the first information bit transmission time, and setting the first information bit transmission time and the number of second carriers to one of coordinate values; And retrieving a second information bit transmission time that minimizes packet transmission energy in the number of first carriers, and setting the second information bit transmission time and the number of first carriers to another one of the coordinate values.

In a method of minimizing packet transmission energy of a power amplifier, the first information bit transmission time is an intermediate value between the maximum and minimum values of the information bit transmission time of the search region, and the number of first carriers is the maximum of the number of carriers in the search region. It is preferred to be the middle value between the value and the minimum value.

In a method of minimizing packet transmission energy of a power amplifier, resetting the search region based on the retrieved one or more coordinate values comprises: selecting a coordinate value having the largest packet transmission energy among the retrieved one or more coordinate values; And setting the information bit transmission time of the selected coordinate value and the number of carriers to the maximum value of the information bit transmission time of the search region and the maximum value of the number of carriers of the search region.

The computer readable medium according to the present invention includes instructions for performing a method of minimizing packet transmission energy of a power amplifier.

An apparatus for scheduling a link in a multi-carrier system according to the present invention, the carrier number calculation unit for obtaining the number of carriers that can minimize the packet transmission energy of the power amplifier; And a scheduling unit that schedules the link based on the estimated number of carriers.

The apparatus for scheduling a link in a multi-carrier system further includes an information bit transmission time unit for obtaining an information bit transmission time for minimizing the packet transmission energy of the power amplifier, wherein the scheduling unit is configured to determine the link of the estimated carrier. It is desirable to schedule the link based on the number and information bit transmission time.

In an apparatus for scheduling a link to minimize packet transmission energy of a power amplifier in a multi-carrier system according to the present invention, the scheduling apparatus includes a processor and a memory, the processor including a maximum value of information bit transmission time and a minimum value of information bit transmission time. Set a search area including a maximum value of the number of carriers and a minimum value of the number of carriers, search for one or more coordinate values that minimize packet transmission energy within the search area, and search based on the searched one or more coordinate values. The coordinate value includes the information bit transmission time and the number of carriers.

Link scheduling apparatus in a multi-carrier wireless communication system according to the present invention includes a processor and a memory, the processor comprising: a maximum value of the information bit transmission time, the minimum value of the information bit transmission time, the maximum value of the number of carriers and the carrier Set a search area containing the minimum number of counts, search for one or more coordinate values within the search area that minimizes packet transmission energy, reset the search area based on the retrieved one or more coordinate values, and the coordinate values transmit information bits Time and number of carriers.

In a link scheduling apparatus in a multi-carrier wireless communication system, the scheduler performs repetition of retrieval of one or more coordinate values and retrieval of the retrieval area until the retrieval area is converged, the information bit transmission time when the retrieval area is converged, and It is desirable to schedule the power amplifier by the number of carriers.

In the link scheduling apparatus in the multi-carrier wireless communication system, setting the search area by the scheduler includes: setting a predetermined initial information bit transmission time to a minimum value of the information bit transmission time of the search area; Setting the number of predetermined first carriers to the minimum value of the number of carriers in the search area; Searching for the number of carriers capable of minimizing packet transmission energy of the power amplifier at a minimum value of the information bit transmission time of the search region and setting the maximum number of carriers in the search region; And searching for an information bit transmission time for minimizing the packet transmission energy of the power amplifier at a minimum value of the number of carriers in the search region and setting the information bit transmission time to the maximum value of the information bit transmission time in the search region.

In a link scheduling apparatus in a multi-carrier wireless communication system, retrieving one or more coordinate values may include selecting a first information bit transmission time between a maximum value and a minimum value of the information bit transmission time of a search area; Selecting the number of first carriers between the maximum value of the number of carriers and the maximum value of the number of carriers in the search area; Retrieving the number of second carriers that minimizes packet transmission energy in the first information bit transmission time and setting the first information bit transmission time and the number of second carriers to one of coordinate values; Retrieving a second information bit transmission time that minimizes packet transmission energy in the number of first carriers, and setting the second information bit transmission time and the number of first carriers to another one of coordinate values.

In a link scheduling apparatus in a multi-carrier wireless communication system, the first information bit transmission time is an intermediate value between the maximum value and the minimum value of the information bit transmission time in the search region, and the number of the first carriers is the maximum number of carriers in the search region. It is preferred to be the middle value between the value and the minimum value.

In the link scheduling apparatus in the multi-carrier wireless communication system, resetting the search region based on the retrieved one or more coordinate values includes: selecting a coordinate value having the largest packet transmission energy among the retrieved one or more coordinate values; And setting the information bit transmission time of the selected coordinate value and the number of carriers to the maximum value of the information bit transmission time of the search region and the maximum value of the number of carriers of the search region.

The mobile communication terminal according to the present invention includes a link scheduling apparatus in a multi-carrier wireless communication system.

The present invention calculates the packet transmission time and the number of subcarriers to maximize energy efficiency in consideration of the correlation between the transmission time of information bits and the number of subcarriers according to the characteristics of the power amplifier in the mobile communication terminal, By performing communication link scheduling, there is an effect that the amount of energy consumed in power amplification can be reduced.

Hereinafter, with reference to the accompanying drawings will be described in detail an industrial apparatus test method and system according to a preferred embodiment of the present invention. Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully appreciate the scope of the invention to those skilled in the art, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

As shown in FIG. 1, when a signal is input to the pin 101, the power amplifier has a size suitable for transmitting the input signal to a pass band based on the energy provided from the DC voltage 103. Amplifies the signal to output to the P _tx (105). In this case, the power amplifier varies the amount of power required to amplify the signal according to the range of the signal input to the P _in (101), which can be expressed as Equation 1 below. Equation 1 shows the nonlinear amplification efficiency of the power amplifier.

Here, P _pa is the power required for the amplification of the signal in the terminal, that is, the power amplifier, P _tx is the power of the signal transmitted through the passband in the power amplifier, P _{tx , max} is the maximum limit of P _tx Means. In addition, η (P _tx ) denotes amplification efficiency, which is a nonlinear function having P _tx as a parameter, and can be represented by Equation 2 below, for example, of a power amplifier model of a communication device which is commonly used.

Here, Equation 2 represents an energy amplification efficiency in consideration of the characteristics of the power amplifier.

In the following description, as shown in Equations 1 and 2, the relationship between the transmission time and the energy of information bits is calculated based on the nonlinear relationship between power consumption P _pa and amplification efficiency η (P _tx ) with P _tx . Let's look at it.

The energy consumed by the mobile communication terminal to transmit the actual signal is the energy provided by the power amplifier from the DC voltage 103, which can be expressed by Equation 3 below. Equation 3 below represents energy consumed by the terminal for uplink signal transmission.

Here, E _r (t) means energy consumed by the terminal for the signal transmission, t means time for transmitting one information bit, and P _tx , the signal power transmitted in the passband, It can be expressed as Equation 4 using Shannon's capacity formula.

Here, N denotes noise power in a Gaussian channel, and α denotes attenuation of power according to distance. As in Equation 3, the energy consumed by the UE for uplink signal transmission may be redefined as in Equation 5 using Equation 2.

Here, when the efficiency of the energy redefined as shown in Equation 5 is represented as a graph, it may be represented as shown in FIG. 2 is a graph illustrating energy efficiency according to transmission time in the prior art and the present invention. In the following description, the horizontal axis represents one information bit transmission time, and the vertical axis represents energy consumed. 2 is a graph E _c (t) showing a correlation between the transmission time and energy of information bits without considering the characteristics of the power amplifier according to the related art, and information bits considering the characteristics of the power amplifier according to the present invention. A graph E _r (t) is shown showing the correlation between the transmission time and the energy of. As shown in FIG. 2, the graph that does not consider the characteristics of the power amplifier in the related art decreases the energy consumption as the time for transmitting one information bit increases, whereas the graph considers the characteristics of the power amplifier according to the present invention. The energy consumption decreases until the time for transmitting one information bit reaches a specific time, but when the transmission time increases beyond the specific time, the energy consumption increases again. That is, considering the characteristics of the power amplifier, it can be seen that there is an optimal transmission time for minimizing the energy consumed by the terminal to transmit data. This satisfies 0 to 30 dB, which is a range of signal to noise ratio (SNR) in which a terminal transmits data in a general cellular system.

On the other hand, recently used wireless transmission method is orthogonal frequency division multiplexing (OFDM) (for example, IEEE 802.16e) or orthogonal frequency division multiple access (OFDMA) using a multi-carrier is the mainstream, as described above Scheduling, which only considers the energy and transmission time consumed by the amplifier, is no longer valid in a multi-carrier system. In the multi-carrier method, the peak-to-average power ratio (PAPR) is high due to the overlapping of subcarriers of various frequencies. In this case, in order to prevent distortion of the output signal, adjustment of the input / output power range of the power amplifier is required. Inevitable It is necessary to build a new energy model based on the power efficiency of the power amplifier considering PAPR, and to think about how to quickly find and allocate the number of the most energy efficient subcarriers and the information bit transmission time.

In order to derive the relationship between the efficiency of the power amplifier and the number of carriers when a plurality of carriers are used, an example of the relationship between the information bit transmission time and the power amplifier efficiency as shown in Equation 2 is given by Equation 6 below. Generalize and model.

Where a and b are constant parameters applied when modeling a specific power amplifier. One additional consideration here is the effect of PAPR caused by multicarriers. The efficiency of the power amplifier considering the effect of the above PAPR will be derived below.

Power amplifiers are devices in which peak power is limited. Therefore, when the input signal passes through the power amplifier, the output value becomes a constant maximum when the magnitude of the input signal becomes larger than the predetermined magnitude. That is, the output is truncated at a certain value. This truncation increases the nonlinear distortion of the signal and increases the bit error rate (BER) of the received signal. Therefore, to reduce this nonlinear distortion, the power amplifier must adjust the linear operating region to account for the peak value of the input signal. As such, the peak value of the input signal and the linear operating region of the power amplifier have an important correlation with each other, and the efficiency of the power amplifier varies according to the peak value and the linear operating region of the power amplifier.

PAPR is defined as in Equation 7 below.

x (t) is a signal input to the power amplifier, the numerator of the PAPR represents the peak value of the power of the input signal over a specific time range, and the denominator of the PAPR represents the average value of the power of the input signal.

The drain efficiency in a class A type power amplifier may be defined as Equation 8 below.

η means the efficiency of the power amplifier, P _DC means the direct current (DC) supplied to the power amplifier, P _{o , avg} Is output average power, P _{o , max} is output maximum power, P _{i , avg} is input average power, P _{i , max} is input maximum power.

The first relation in Equation 8 is derived from the definition of the efficiency of the power amplifier.

The relationship of P _{DC =} 2P _{o , max} is the design rule of a class A power amplifier. The relationship of P _{o , avg ,} P _{o , max} , P _{i , avg ,} P _{i , max} is shown in FIG. 3.

Meanwhile, the Complementary CDF of PAPR may be modeled by Equation 9.

Here, γ is a scalar value of PAPR and m is the number of subcarriers. The above equation means that the probability that the PAPR is greater than a specific value γ is F when m subcarriers are used. If this equation is rearranged again for γ, it can be expressed by the following equation (10).

Considering the equations regarding the efficiency of the power amplifiers of Equations 6 and 8 above, it is possible to derive an equation regarding the efficiency of the power amplifier as shown in Equation 11 below.

Here, a 'is a new constant considered by reflecting the offset after considering the PAPR considered when generating the data sheet of the power amplifier to the constant a proposed in Equation 6. That is, a '= a? PAPR.

For example, if the data sheet of the power amplifier has obtained the efficiency based on the average PAPR of 1024 multi-carriers, the efficiency of the system having m multi-carriers can be represented by the following equation (12).

In addition, the following equation (13) can be derived using equations (10) and (12).

Referring to the efficiency relation derived from Equation 13, first, in a situation where m, the number of subcarriers, is fixed, the efficiency varies according to a ', and the information bit transmission time and the power amplifier as derived from Equations 1 to 6 Will have a relationship with That is, there is an information bit transmission time for maximizing the efficiency of the power amplifier, and if the information bit transmission time is extended beyond that, the efficiency of the power amplifier is deteriorated.

The same conclusion is also drawn when viewed from the frequency axis. In the above equation, as the number of subcarriers m increases, the point where the PAPR increases and the efficiency decreases again appears. Thus, there is a number of subcarriers that maximize the efficiency of the power amplifier.

As a result, it can be seen that there is a transmission time that guarantees the minimum energy and the number of subcarriers. For example, when transmitting 650 bits of data, the energy consumption of the power amplifier was measured while changing the transmission time and the number of subcarriers under the following conditions.

Experimental Environment

IEEE 802.16e PHY Parameter

Data length: 650 bits

-AWGN channel noise power: -97 dBm / 50 MHz (-174 dBm / Hz)

Maximum power: 200 mW

Distance: 400 m

Complementary CDF (CCDF) of PAPR, F = 0.01

Experimental results according to the above experiments are shown in Figs. 4A and 4B.

4A and 3D graphs of energy consumed according to the number and transmission times of subcarriers are shown. FIG. 4B is a two-dimensional graph showing the number and transmission times of subcarriers in the graph of FIG. 4A on each axis. It is a drawing. From the above experimental results, it can be seen that there is a combination of the number of subcarriers with the minimum transmission power and the transmission time in a situation where data to be transmitted is given, and such a combination can be found.

In order to find the above combination, it is necessary to present an appropriate search algorithm. A resource allocation scheme of the IEEE 802.16e system based on OFDMA is assumed and an optimization scheme thereof is proposed. Resource allocation of IEEE 802.16e is performed through control data in the form of a resource map that periodically transmits a resource of a repeated MAC frame in front of the MAC frame. That is, the system knows the amount of information that users should send before the frame starts, and based on this, the system sends a map type information to each user of a resource of appropriate size. The simplest way to do this is to do a full search. The full search refers to a method of calculating energy consumed by the power amplifier for the samples of all subcarriers and transmission time, and then searching for the energy of the power amplifier which is the minimum among them. However, this approach has too much computation. Therefore, a simpler and faster resource allocation method is needed.

5 shows a diagram illustrating a method for finding the number of subcarriers and the information bit transmission time with the minimum transmission power.

In step S610, the first solution is searched, the transmission time (init_t1) for minimizing energy at the minimum number of carriers (init_m1) is searched, and the number of carriers (init_m2) for minimizing energy at the minimum transmission time (init_t2) is searched. do. That is, after obtaining the transmission time init_t1 when energy is minimized when the minimum number of carriers is constant as init_m1, the number of carriers whose energy is minimized when the minimum transmission time is constant as init_t2 is searched for init_m2. init_m1 need not necessarily be the minimum number of carriers and may be a predetermined constant value. init_t2 does not necessarily have to be a minimum information bit transfer time, but may also be a predetermined constant value.

After that, in step S615, a search area is set based on the parameters obtained in S610. The search area (search range) of the information bit transfer time is set to init_t2 or more and init_t1 or less, and the search area of the number of carriers is set to init_m1 or more and init_m2 or less. In addition, t_center is an intermediate value between init_t1 and init_t2, and m_center is an intermediate value between init_m1 and init_m2.

Thereafter, in step S620, line search is performed at each center point. That is, when the transmission time is constant as t_center, the number of carriers that minimizes energy is called m_min, and the energy value at that time is calculated as E_1. In addition, the transmission time for minimizing energy when the number of carriers is m_center is called t_min, and the energy value at that time is calculated and called E_2.

In step S625, the values of E_1 and E_2 are compared. If E_1 is greater than E_2, the flow proceeds to step S630, otherwise, the flow goes to step S635.

In step S630, the initial point is redefined, and the expression is equal to init_t1 = t_center and init_m1 = m_min. In other words, when E1 is larger than E2, the pair of coordinates (t_center, m_min) for setting the energy value to E_1 is set as a new initial point.

In step S635, the initial point is redefined, and the expression is equal to init_t2 = t_min and init_m2 = m_center. In other words, when E1 is smaller than E2, the pair of coordinates (t_min, m_center) that sets the value of energy to E_2 is set as a new initial point.

In step S640, it is determined whether the search area converges. The convergence is determined by whether the size of the search range of the bit information transmission time of the search area is smaller than 1 or the size of the search range of the number of carriers in the search area is smaller than 2. That is, when the difference between ini_t1 and init_t2 is less than 2 or the difference between init_m2 and init_m1 is less than 2, the convergence condition is satisfied. If the search area converges, the process proceeds to step S645 to find the final solution in the reduced search area. If the search area does not converge, the flow advances to step S615 to resume the search.

6A-6E show an example of a process of actually finding the information bit transmission time and the number of subcarriers by the method shown in FIG. Hereinafter, a method of finding a transmission time and the number of subcarriers will be described in detail with reference to the above two drawings.

Referring to FIG. 6A, when the minimum value of energy is first searched when the number of first subcarriers is fixed to 2, it is obtained that the minimum value of energy is 5.16 and the transmission time at that time is 117. In other words, after fixing the horizontal axis, find the point that minimizes energy on the horizontal axis. Then, searching for the minimum value of energy when fixing the transmission time to 5 finds that the minimum value of energy is 2.48 and the number of carriers at that time is 1107, i.e., after fixing the vertical axis, the minimum energy on the vertical axis is fixed. Find the point to make. This corresponds to step S610 of FIG. 5, init_m1 is set to 2, init_t1 is set to 117, init_m2 is set to 1107, and init_t2 is set to 5.

Referring to FIG. 6B, it can be seen that the search area of the transmission time is set to 5 or more and 117 or less and the search area of the number of carriers is set to 2 or more and 1107 or less. This corresponds to defining the search area in step S615.

In FIG. 6C, when the minimum energy is obtained when the transmission time is fixed to 89, which is the median transmission time in the search region, the energy is 3.31 when the number of carriers is 13. If the minimum energy when the number of carriers is fixed to 555, which is the median number of carriers in the search region, is obtained, it can be seen that the energy is 2.20 when the transmission time is 30. This corresponds to finding two coordinate pairs existing in the search area in step S620.

In FIG. 6D, a process of selecting the transmission time 89 and the number 13 of carriers when the energy consumed in the power amplification is 3.31, which is the maximum value among the above two energies, is illustrated. 6E shows a process of setting a new search area by setting (89, 13), which is the pair of the selected transmission time and carrier, as one coordinate of the search area of the new area. This corresponds to the steps of steps S625, S630, and S635.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is a diagram showing the structure of a general power amplifier.

2 is a diagram illustrating an energy efficiency graph according to information transmission time, which is considered based on the prior art and the technique proposed by the present invention in a system having a fixed subcarrier.

3 graphically illustrates the input and output relationships of an ideal linear power amplifier.

FIG. 4A is a diagram illustrating a three-dimensional graph of energy consumed according to the number of subcarriers and the transmission time, which is considered based on the energy efficiency relationship considered in the present invention in transmitting a certain amount of information.

FIG. 4B is a diagram of a two-dimensional graph showing the number of subcarriers and the transmission time in each axis of the graph of FIG. 4A.

5 shows a diagram illustrating a method for finding the number of subcarriers and the information bit transmission time with the minimum transmission power.

6A-6E show an example of a process of actually finding the information bit transmission time and the number of subcarriers by the method shown in FIG.

*** Description of the symbols for the main parts of the drawings ***

S610: Initial solution search step S615: Search area definition step

S620: line search step S625: energy value comparison step

Claims (19)

delete delete A method of minimizing packet transmission energy of a power amplifier in a multicarrier communication system, Setting a search region including a maximum value of the information bit transmission time, a minimum value of the information bit transmission time, a maximum value of the number of carriers, and a minimum value of the number of carriers; Retrieving at least one coordinate value within the retrieval area that minimizes packet transmission energy; And Resetting the search region based on the retrieved one or more coordinate values, Wherein the coordinate value comprises information bit transmission time and the number of carriers. The method of claim 3, wherein Retrieving the one or more coordinate values and resetting the search region are repeatedly performed until the search region converges, Scheduling the power amplifier with an information bit transmission time and the number of carriers when the search region is converged. The method of claim 3, wherein Setting the search area, Setting a predetermined initial information bit transmission time to a minimum value of the information bit transmission time of the search region; Setting a number of predetermined first carriers to a minimum value of the number of carriers in the search area; Retrieving the number of carriers capable of minimizing packet transmission energy of the power amplifier from the minimum value of the information bit transmission time of the search region and setting the maximum number of carriers of the search region; And Retrieving an information bit transmission time capable of minimizing packet transmission energy of the power amplifier at a minimum value of the number of carriers in the search region, and setting the packet to the maximum value of the information bit transmission time in the search region. How to minimize energy. The method of claim 3, wherein Retrieving the one or more coordinate values, Selecting a first information bit transmission time between a maximum value and a minimum value of the information bit transmission time of the search region; Selecting the number of first carriers between the maximum value of the number of carriers and the maximum value of the number of carriers in the search area; Retrieving the number of second carriers for minimizing the packet transmission energy in the first information bit transmission time and setting the first information bit transmission time and the number of the second carriers to one of the coordinate values; Retrieving a second information bit transmission time that minimizes the packet transmission energy from the number of first carriers, and setting the second information bit transmission time and the number of the first carriers to another one of the coordinate values. Packet transmission energy minimization method. The method of claim 6, The first information bit transmission time is an intermediate value between the maximum value and the minimum value of the information bit transmission time of the search region, And the number of the first carriers is a middle value between a maximum value and a minimum value of the number of carriers in the search region. The method of claim 6, Resetting the search area based on the retrieved one or more coordinate values, Selecting a coordinate value having the largest packet transmission energy among the retrieved one or more coordinate values; And And setting the information bit transmission time and the number of carriers of the selected coordinate value to a maximum value of the information bit transmission time of the search region and a maximum value of the number of carriers of the search region. A computer readable medium comprising instructions for performing the method of claim 3. delete delete An apparatus for scheduling a link to minimize packet transmission energy of a power amplifier in a multicarrier system, comprising: The scheduling apparatus includes a processor and a memory, The processor is Setting a search area including a maximum value of the information bit transmission time, a minimum value of the information bit transmission time, a maximum value of the number of carriers, and a minimum value of the number of carriers, Search for one or more coordinate values within the search region that minimize packet transmission energy, Reset the search area based on the retrieved one or more coordinate values, Wherein the coordinate value includes information bit transmission time and the number of carriers. A link scheduling apparatus in a multicarrier wireless communication system, Includes a processor and memory, The processor comprising: Setting a search area including a maximum value of the information bit transmission time, a minimum value of the information bit transmission time, a maximum value of the number of carriers, and a minimum value of the number of carriers, Search for one or more coordinate values within the search region that minimize packet transmission energy, Reset the search area based on the retrieved one or more coordinate values, Wherein the coordinate value includes information bit transmission time and the number of carriers. The method of claim 13, The scheduler is repeatedly performed to search the one or more coordinate values and to reset the search area until the search area converges, And schedule a power amplifier by the information bit transmission time and the number of carriers when the search region converges. The method of claim 13, The scheduler sets the search area, Setting a predetermined initial information bit transmission time to a minimum value of the information bit transmission time of the search region; Setting a number of predetermined first carriers to a minimum value of the number of carriers in the search area; Searching for the number of carriers capable of minimizing packet transmission energy of a power amplifier at a minimum value of the information bit transmission time of the search region and setting the maximum number of carriers in the search region; And And searching for an information bit transmission time for minimizing packet transmission energy of the power amplifier at a minimum value of the number of carriers in the search region, and setting the information bit transmission time to the maximum value of the information bit transmission time in the search region. . The method of claim 13, Retrieving the one or more coordinate values, Selecting a first information bit transmission time between a maximum value and a minimum value of the information bit transmission time of the search region; Selecting the number of first carriers between the maximum value of the number of carriers and the maximum value of the number of carriers in the search area; Retrieving the number of second carriers for minimizing the packet transmission energy in the first information bit transmission time, and setting the first information bit transmission time and the number of the second carriers to one of the coordinate values; Retrieving a second information bit transmission time for minimizing the packet transmission energy from the number of the first carriers, and setting the second information bit transmission time and the number of the first carriers to another one of the coordinate values. Scheduling device The method of claim 16, The first information bit transmission time is an intermediate value between the maximum value and the minimum value of the information bit transmission time of the search region, And the number of the first carriers is an intermediate value between a maximum value and a minimum value of the number of carriers in the search region. The method of claim 16, Resetting the search area based on the retrieved one or more coordinate values, Selecting a coordinate value having the largest packet transmission energy among the retrieved one or more coordinate values; And And setting the information bit transmission time and the number of carriers of the selected coordinate value to the maximum value of the information bit transmission time of the search region and the maximum value of the number of carriers of the search region. 19. A mobile terminal comprising the scheduling device of any of claims 13-18.

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