KR102115074B1 - Apparatus and Method for Reducing PAPR using SLM - Google Patents

Abstract

Disclosed is an apparatus and method for reducing PAPR using SLM. The disclosed apparatus includes a group setting unit that divides multiple antennas into a plurality of groups and sets the number of phase sequences to be used in each group; A phase selector for selecting one of a plurality of phase sequences set to be used for each group for each group; And a phase application unit that transmits a signal by applying the selected phase sequence to all antennas belonging to each group. According to the disclosed apparatus and method, it is possible to effectively reduce PAPR while using SLM in a multi-antenna environment.

Description

Apparatus and Method for Reducing PAPR using SLM}

Embodiments of the present invention relates to an apparatus and method for reducing PAPR, and more particularly, to an apparatus and method for reducing PAPR using Selected Mapping (SLM).

In a wireless communication system including a multi-carrier transmission system, a peak to average power ratio (PAPR) of a signal is a factor influencing the performance of a system.

The power amplifier of the transmitter has a limited linear amplification section, and when the PAPR is large, amplification can be performed in a section that exceeds the linear amplification section, which causes distortion of the signal, which increases the BER of the system and results in data rate loss. This is a major factor coming.

Therefore, in the wireless communication system, PAPR reduction is essential.

The most commonly used method for PAPR reduction is clipping of the signal. The clipping method is a method of clipping a signal to a predetermined signal level when the signal strength is higher than a predetermined level. This clipping method is advantageous in terms of PAPR because it involves distortion of the signal, but it is a method that causes loss in terms of data rate and BER.

For this reason, several methods for reducing PAPR without distortion of a signal have been proposed, and the most representative method is a SLM (Selected Mapping) method that lowers PAPR by adjusting the phase of the signal. The SLM method is a method of adjusting the phase by selecting the most effective phase sequence among a plurality of phase sequences, and additional information including the selected phase sequence information must be shared with the receiving end.

This SLM method has a problem in that it is difficult to be realistically used because a large amount of additional information needs to be transmitted in a MIMO environment where a large number of antennas are used and a massive-MIMO environment.

One aspect of the present invention is to propose a method and apparatus that can effectively reduce PAPR while using SLM in a multi-antenna environment.

According to an aspect of the present invention, a PAPR reduction apparatus using SLM in a multi-antenna environment, comprising: a group setting unit for dividing the multi-antenna into a plurality of groups and setting the number of phase sequences to be used in each group; A phase selector for selecting one of a plurality of phase sequences set to be used for each group for each group; And a phase application unit for transmitting signals by applying the selected phase sequence to all antennas belonging to each group.

The group setting unit, PAPR monitoring unit for obtaining the PAPR information for each of the multiple antennas; A group number and an antenna setting unit for each group for setting the number of groups and antennas belonging to each group based on the PAPR information for each of the multiple antennas; And a phase sequence number setting unit that sets the number of phase sequences to be used for each set group.

The group number and the antenna setting unit for each group sets a group such that antennas having similar PAPRs belong to the same group.

The phase sequence number setting unit is configured to use a relatively large number of phase sequences in a group consisting of antennas having a relatively high PAPR.

The group setting unit, a group number setting unit for arbitrarily setting the number of groups; A set-by-drop antenna setting unit for setting a set group-specific antenna; A phase sequence number setting unit for setting the number of phase sequences to be used for each set group; And an update control unit for controlling the update of the set number of groups, the number of antennas and phase sequences for each group.

The phase selection unit calculates energy efficiency based on the selected phase sequence, and the update control unit at least one of the set number of groups, the number of antennas for each crop, and the number of phase sequences when the calculated energy efficiency is less than a preset first boundary value. Control to update.

The phase selection unit selects a phase sequence corresponding to the smallest value of the maximum PAPR for antennas belonging to a group among phase sequences set for a specific group.

The update control unit updates the number of phase sequences per group when the energy efficiency is less than the first threshold value and is greater than the second threshold value, and the energy efficiency is greater than the third threshold value and less than the second threshold value. If the number of phase sequences for each group and the antenna for each group is updated, and the energy efficiency is less than a third threshold, the number of groups, the antenna for each group, and the number of phase sequences for each group are controlled to be updated.

According to another aspect of the present invention, a PAPR reduction method using SLM in a multi-antenna environment, comprising: (a) obtaining PAPR information for each multi-antenna; Dividing the multi-antenna into a plurality of groups and setting the number of phase sequences to be used in each group based on the obtained PAPR information for each multi-antenna (b); Selecting one of a plurality of phase sequences set to be used for each group by group (c); There is provided a PAPR reduction method using SLM comprising the step (d) of applying a phase sequence selected for each group to all antennas belonging to each group.

According to another aspect of the invention, the step of arbitrarily setting the number of groups, the antenna for each set group and the number of phase sequences to be used for each set group (a); Selecting one of a plurality of phase sequences set to be used for each group by group (b); Calculating (c) energy efficiency based on the phase sequence selected in step (b) and determining whether the energy efficiency is less than a preset first boundary value; Updating (d) at least one of the number of groups in the step (a), the antennas for each set group, and the phase sequence to be used for each set group when the energy efficiency is smaller than a preset first boundary value; And (e) applying a phase sequence selected for each group to all of the antennas belonging to each group when the energy efficiency is greater than a preset first boundary value, thereby transmitting a signal. Is provided.

According to the present invention, it is possible to effectively reduce the PAPR while using the SLM in a multi-antenna environment.

1 is a view for explaining the SLM applied to the present invention.
2 is a diagram conceptually showing a group-based SLM according to an embodiment of the present invention.
3 is a block diagram showing the structure of a PAPR reduction device using SLM according to an embodiment of the present invention.
4 is a block diagram showing the structure of a group setting unit according to a first embodiment of the present invention.
5 is a block diagram showing the structure of a group setting unit according to a second embodiment of the present invention.
6 is a flow chart showing the overall flow of the PAPR reduction method using SLM according to the first embodiment of the present invention.
7 is a flowchart illustrating the overall flow of a PAPR reduction method using SLM according to a second embodiment of the present invention.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals are used for similar components.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining the SLM applied to the present invention. The SLM method will be described first, and a PAPR reduction method according to an embodiment of the present invention will be described.

Referring to FIG. 1, a typical SLM device includes a serial / parallel converter (S / P, 102), a plurality of component-wise multipliers 103, a plurality of LN points IFFT 104, and a selector 105 ).

In FIG. 1, X is a frequency domain signal for the data to be transmitted, X is input to the serial / parallel converter 102, and the serial / parallel converter 102 generates a number of parallel signals for the frequency domain signal X. .

Each of the multiple parallel signals is multiplied by a different phase sequence, where the multiplied phase sequence and the number of phase sequences are preset, and the number of phase sequences is multiplied by the number of parallel signals generated through the serial / parallel converter 102. Corresponds.

The multiplication between each parallel signal and the i-th phase sequence P ⁱ is a component-wise multiplication and operation is performed by the component-wise multiplier 103.

The greater the number of phase sequences multiplied by the parallel signal, the better the PAPR reduction performance, but the more complicated the tradeoff relationship. 1 illustrates an example in which V phase sequences are applied.

Each of the signals multiplied by the phase sequence multiplied by the parallel signal is converted into a time domain signal by the LN point IFFT 104, and V time domain signals x ⁱ are generated.

The selector 105 selects a signal having the lowest PAPR among the V time domain signals and allows the selected signal to be transmitted. Here, L is an oversampling factor and N is a number of subcarriers.

The SLM method described with reference to FIG. 1 is a method of selecting and transmitting only the signal having the lowest PAPR performance after applying multiple phase sequences.

When the signal input to the selector 105 in the SLM method is expressed by an equation, it can be expressed as the following equation (1).

은 IFFT 연산자,

은 위상 시퀀스이고

은 컴포넌트-와이즈 곱셈 연산자이다. In Equation 1 above,

IFFT operator,

Is the phase sequence

Is a component-wise multiplication operator.

When the SLM is used, the transmitting end should provide additional information including the selected phase sequence information to the receiving end, and the receiving end performs decoding using the selected phase sequence information.

In a single antenna transmission / reception system, SLM can be effectively used to reduce PAPR, but in a MIMO environment and a massive-MIMO environment in which multiple antennas are used, additional information needs to be generated and transmitted for each antenna, and thus is difficult to apply. To solve this problem, we propose a group-based SLM method.

2 is a diagram conceptually showing a group-based SLM according to an embodiment of the present invention.

If SLM is applied to a multi-antenna environment such as MIMO, the optimal phase sequence must be determined for each antenna by performing SLM for each antenna, but this method increases complexity due to a large number of additional information.

Referring to FIG. 2, the group-based SLM of the present invention performs grouping on a plurality of antennas to generate a plurality of groups G1, G2, and GN. When grouping is performed, the same phase sequence is applied to antennas belonging to the same group. The group-based SLM of the present invention may be less effective in terms of PAPR reduction compared to the method of applying the optimal phase sequence for each antenna, but it can significantly reduce the number of additional information, so it is useful for MIMO environments and massive-MIMO environments. It can be applied realistically.

When group-based different phase concurrent SLMs (gbdpcSLMs) of different phases based on a group according to an embodiment of the present invention are expressed by Equation, Equation 2 is as follows.

In Equation 2 above, it can be seen that X _{1 '} and X _2' have different antenna signals or the same phase sequence applied, and different phase sequences are applied to each antenna group.

3 is a block diagram showing the structure of a PAPR reduction apparatus using SLM according to an embodiment of the present invention.

Referring to FIG. 3, the PAPR reduction apparatus using SLM according to an embodiment of the present invention includes a group setting unit 300, a phase selection unit 310 for each group, and a phase application unit 320.

The group setting unit 300 functions to set a group for a plurality of antennas and to set the number of phase sequences to be used in each group. Specifically, the group setting unit 300 sets the total number of groups, the number of antennas belonging to each group, and the number of phase sequences to be used in each group.

According to the first embodiment of the present invention, the group setting unit 300 may set a group by monitoring the PAPR of each antenna in real time.

According to the second embodiment of the present invention, the group setting unit 300 may set a group while randomly setting the group and updating the group based on the energy efficiency of the group.

4 is a block diagram showing the structure of a group setting unit according to a first embodiment of the present invention.

Referring to FIG. 4, the group setting unit according to the first embodiment of the present invention may include a PAPR monitoring unit 400, an antenna setting unit 410 for each group and a group and a phase sequence number setting unit 420. .

The PAPR monitoring unit 400 monitors the PAPR of each antenna in real time. For example, the PAPR monitoring unit 400 may arrange antennas in ascending order from the antenna having the highest PAPR to the antenna having the lowest PAPR.

The number of groups and the antenna setting unit for each group 410 sets the number of groups and antennas for each group based on the monitored PAPR. According to a preferred embodiment of the present invention, the number of groups and the antennas for each group are set such that antennas having similar PAPRs belong to the same group.

For example, grouping may be performed such that antennas in which the maximum PAPR and the minimum PAPR of antennas belonging to a group are less than or equal to a preset threshold belong to the same group.

As such, when grouping is performed, a specific group is made of antennas having a relatively high PAPR, and a specific group is made of antennas having a relatively low PAPR.

The phase sequence number setting unit 420 functions to set the number of phase sequences to be applied to each group. The phase sequence number setting unit 420 sets the number of phase sequences based on the PAPR of each group. The number of phase sequences is set such that a relatively large number of phase sequences is used in a group of antennas having relatively high PAPR. The number of phase sequences is set so that a relatively small number of abnormal sequences are used in a group of antennas having a relatively low PAPR.

와 같이 설정된다. For example, it is assumed that the first group to the fourth group are generated, the first group is assumed to be a group consisting of antennas having the highest PAPR, and the fourth group is called a group consisting of antennas having the lowest PAPR. It is assumed that the number of phase sequences set in each group _i is defined as V _i . In this case, the number of phase sequences

Is set as

5 is a block diagram showing the structure of a group setting unit according to a second embodiment of the present invention.

Referring to FIG. 5, the group setting unit according to the second embodiment of the present invention includes a group number setting unit 500, a group antenna setting unit 510, a phase sequence number setting unit 520, and an update control unit 530. Includes.

The first embodiment is an embodiment in which monitoring for PAPR is required. Such PAPR monitoring may increase system complexity and processing time. The second embodiment is an embodiment of setting a group without monitoring PAPR.

The group number setting unit 500 functions to set the total number of groups for grouping antennas. In the initial state, the number of groups is set randomly or based on the grouping result in the previous signal.

The antenna setting unit 510 for each group sets an antenna to belong to each group after setting the number of groups. The number of antennas belonging to each group and the antennas may also be initially set arbitrarily or may be set based on a grouping result in a previous signal. The antenna setting unit for each group may set the same number of antennas for each group, or may set the number of antennas for each group differently.

The phase sequence number setting unit 520 sets the number of phase sequences to be used for each group. The number of phase sequences to be used in each group may also be initially set arbitrarily or may be set based on the number of phase sequences in the previous signal. The phase sequence number setting unit may set the same number of phase sequences used in each group, or may set different number of phase sequences used in each group.

The update control unit 530 functions to update the number of set groups, the number of antennas and phase sequences for each group. In the case of the second embodiment, since the grouping and the number of phase sequences are set based on the arbitrary or past group setting, the effective PAPR reduction performance may not be provided. In this case, the update control unit 530 may include the group number setting unit 500 and each group. The antenna setting unit 510 and the phase sequence number setting unit 520 are controlled to update the setting information.

In the second embodiment, the update control operation by the update control unit 530 will be described in detail again after describing the operation of the phase selection unit 310 for each group.

The phase selection unit 310 for each group serves to select a phase sequence that provides optimal PAPR performance in each set group.

Since the group includes a plurality of antennas, PAPR is different for each phase sequence. According to an embodiment of the present invention, the phase selection unit 310 for each group may use a phase sequence in which the maximum PAPR is the smallest among the plurality of phase sequences used in a specific group for the entire antenna belonging to the group. Select by sequence.

According to another embodiment of the present invention, among the plurality of phase sequences used in a specific group, a PAPR average may be calculated for all antennas belonging to the group and a phase sequence corresponding to the lowest PAPR average may be selected.

Of course, it will be apparent to those skilled in the art that the phase sequence selection showing the optimum performance in addition to the above-described method can be made by various methods from various viewpoints.

In the case of the first embodiment, the phase sequence is selected in the above manner, but in the case of the second embodiment, the phase selector 310 for each group additionally calculates energy efficiency according to the selected phase.

(Watt)의 비로 정의된다. 구체적으로 에너지 효율(EE)은 다음의 수학식 3과 같이 정의될 수 있다.Here, Energy Efficiency (EE) refers to frequency efficiency and power consumption associated with PAPR and power amplifier.

It is defined as the ratio of (Watt). Specifically, energy efficiency (EE) may be defined as in Equation 3 below.

 In Equation 3, the unit of energy efficiency can be expressed as bps / Hz / Watt.

In the second embodiment, the energy efficiency calculated by the phase selection unit 310 for each group is fed back to the update control unit 530. The update control unit 530 determines whether to update or not based on the calculated energy efficiency.

When the calculated energy efficiency is equal to or greater than a preset first boundary value, updating of the set values is not performed, and the phase selected by the phase selection unit 310 for each group is used.

However, when the calculated energy efficiency is less than or equal to a preset first boundary value, the update control unit 530 controls to update the set values.

According to an embodiment of the present invention, the update operation may be controlled using the first to third boundary values. Here, the same relationship as the first boundary value> second boundary value> third boundary value is established.

When the calculated energy efficiency is less than the third boundary value, the update control unit 530 controls to update both the number of groups, the number of antennas for each group, and the number of phase sequences.

When the calculated energy efficiency is greater than the third boundary value or less than the second boundary value, the update control unit 530 controls to update the number of antennas and phase sequences for each group without updating the group number.

When the calculated energy efficiency is greater than the second boundary value or less than the first boundary value, the number of groups and antennas for each group are not updated and controlled so that only the number of phase sequences is updated.

Of course, it will be apparent to those skilled in the art that other update methods may be applied in addition to the above-described update method.

When the update is made, the phase sequence selection for each group and energy efficiency calculation are performed again, and the update is repeated until the energy efficiency becomes equal to or higher than the first threshold value.

The phase application unit 320 transmits a signal by applying a phase sequence selected for each group. As described above, the selected phase sequence is applied to all antennas belonging to each group.

6 is a flow chart showing the overall flow of the PAPR reduction method using SLM according to the first embodiment of the present invention.

Referring to FIG. 6, first, PAPR information for a signal to be transmitted for each antenna is obtained through monitoring (step 600).

When the PAPR for each antenna is obtained, grouping of the antennas is performed based on the obtained PAPR (step 602). As described above, grouping is performed such that antennas having similar PAPRs belong to the same group.

When grouping is completed, the number of phase sequences to be used for each group is determined (step 604). The number of phase sequences is determined so that groups formed of antennas with relatively high PAPR use a larger number of phase sequences.

When the number of phase sequences for each group is determined, a phase sequence having optimal PAPR performance for each group is selected (step 606). As described above, a phase sequence in which the maximum PAPR is the smallest among the antennas belonging to the group may be selected, or a phase sequence in which the PAPR average is lowest for the entire antennas in the group may be selected.

When the phase sequence for each group is determined, a signal is transmitted by applying the selected phase sequence to the antennas belonging to each group (step 608).

7 is a flowchart illustrating the overall flow of a PAPR reduction method using SLM according to a second embodiment of the present invention.

Referring to FIG. 7, the number of groups for transmit antennas, the number of antennas belonging to each group, and the number of phase sequences to be used in the group are set (step 700).

When the number of groups, antennas belonging to the group, and the number of phase sequences are determined, a phase sequence to be applied to each group is selected (step 702). As described above, a phase sequence in which the maximum PAPR is the smallest among the antennas belonging to the group may be selected, or a phase sequence in which the PAPR average is lowest for the entire antennas in the group may be selected.

When the phase sequence is selected, energy efficiency is calculated by applying the selected phase sequence (step 704).

When the energy efficiency is calculated, it is determined whether the calculated energy efficiency is greater than or equal to a preset threshold (706).

If it is equal to or greater than a preset threshold, a signal is transmitted by applying the selected phase sequence (step 708). However, if the calculated energy efficiency is less than or equal to a preset threshold, the step of setting the number of groups, antennas belonging to each group, and the number of phase sequences to be used in the group is repeated.

As described above, in the present invention, specific matters such as specific components and the like have been described by limited embodiments and drawings, but these are provided only to help the overall understanding of the present invention, and the present invention is not limited to the above embodiments , Anyone having ordinary knowledge in the field to which the present invention pertains can make various modifications and variations from these descriptions. Accordingly, the spirit of the present invention should not be limited to the described embodiments, and should not be determined, and all claims that are equivalent or equivalent to the scope of the claims as well as the claims described below belong to the scope of the spirit of the invention. .

Claims (15)

As a PAPR reduction device using SLM in a multi-antenna environment,
A group setting unit which divides the multiple antennas into a plurality of groups and sets the number of phase sequences to be used for each group;
A phase selector for selecting one of a plurality of phase sequences set to be used for each group by group; And
It includes a phase application unit for transmitting a signal by applying the selected phase sequence for all antennas belonging to the group,
The group setting unit,
A PAPR monitoring unit for acquiring PAPR information for each antenna;
A group number and a group antenna setting unit for setting the number of groups and antennas belonging to each group based on the PAPR information for each antenna; And
And a phase sequence number setting unit for setting the number of phase sequences to be used for each set group.
delete According to claim 1,
The number of groups and the antenna setting unit for each group is a PAPR reduction apparatus using SLM, characterized in that to set the group so that antennas having similar PAPR belong to the same group.
According to claim 3,
The phase sequence number setting unit is configured to use a relatively large number of phase sequences in a group consisting of antennas with a relatively high PAPR PAPR reduction apparatus using SLM.
According to claim 1,
The group setting unit,
A group number setting unit for arbitrarily setting the number of groups;
A group-specific antenna setting unit for setting the set group-specific antennas;
A phase sequence number setting unit for setting the number of phase sequences to be used for each set group; And
And an update control unit controlling update of the set number of groups, antennas for each group, and number of phase sequences.
The method of claim 5,
The phase selection unit calculates energy efficiency based on the selected phase sequence, and the update control unit at least one of the set number of groups, the number of antennas for each group, and the number of phase sequences when the calculated energy efficiency is less than a preset first boundary value. PAPR reduction device using SLM, characterized in that to control to update.
The method of claim 1 or 5,
The phase selection unit PAPR reduction apparatus using SLM, characterized in that for selecting a phase sequence corresponding to the smallest value of the maximum PAPR for the antennas belonging to the group among the phase sequences set for a specific group.
The method of claim 6,
The update control unit updates the number of phase sequences to be used for each group when the energy efficiency is less than the first threshold value and is greater than the second threshold value, and the energy efficiency is greater than the third threshold value and greater than the second threshold value. If less, the number of phase sequences to be used for each group and the antennas for each group are updated, and when the energy efficiency is less than a third threshold, the number of groups, the antennas for each group, and the number of phase sequences to be used for each group are controlled to be updated. PAPR reduction device using SLM, characterized in that.
As a PAPR reduction method using SLM in a multi-antenna environment,
Obtaining PAPR information for each antenna (a);
Dividing the multiple antennas into a plurality of groups and setting the number of phase sequences to be used for each group based on the obtained PAPR information for each antenna (b);
Selecting one of a plurality of phase sequences set to be used for each group by group (c);
A step (d) of transmitting a signal by applying a phase sequence selected for each group to all antennas belonging to the group is included.
The step (b) is a PAPR reduction method using SLM, characterized in that a group is set so that antennas having similar PAPR belong to the same group.

delete The method of claim 9,
The step (b) is a method of reducing PAPR using SLM, characterized in that a relatively large number of phase sequences is set to be used for a group of antennas having a relatively high PAPR.
The method of claim 9,
In step (c), a PAPR reduction method using SLM is characterized in that a phase sequence corresponding to the smallest value of the maximum PAPR for antennas belonging to a group is selected from among the phase sequences set for a specific group.
(A) arbitrarily setting the number of groups, the antennas for each set group, and the number of phase sequences to be used for each set group;
Selecting one of a plurality of phase sequences set to be used for each group by group (b);
Calculating (c) energy efficiency based on the phase sequence selected in step (b) and determining whether the energy efficiency is less than a preset first boundary value;
Updating (d) at least one of the number of groups in step (a), the antennas for each set group, and the phase sequence to be used for each set group when the energy efficiency is less than the first boundary value; And
And when the energy efficiency is greater than the first boundary value, transmitting a signal by applying the phase sequence selected for each group to all antennas belonging to the group (e), thereby reducing PAPR using SLM. .
The method of claim 13,
In step (b), a PAPR reduction method using SLM is characterized in that a phase sequence corresponding to the smallest value of the maximum PAPR for antennas belonging to a group is selected from among the phase sequences set for a specific group.
The method of claim 13,
In step (d), when the energy efficiency is less than the first boundary value and is greater than a second boundary value, the number of phase sequences to be used for each group is updated, and the energy efficiency is greater than a third boundary value and the second boundary If less than the value, the number of phase sequences to be used for each group and the antennas for each group are updated. If the energy efficiency is less than the third boundary value, the number of groups, the antenna for each group, and the number of phase sequences to be used for each group are updated. PAPR reduction method using SLM characterized in that the control.

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