KR102313984B1 - Method and apparatus for receiving in beam space multiple input multiple output system - Google Patents

Abstract

When a set event occurs, the receiving apparatus of the beam space multiple input multiple output (MIMO) system sequentially forms a beam corresponding to the entire beam base pattern during a corresponding one symbol period to perform full beam scanning and communication, and the Effective beam communication is performed by reducing the number of beam base patterns used for communication by using the result of performing the full beam scanning and communication during the remaining symbol periods except for the symbol period in which all beam scanning and communication are performed.

Description

RECEIVING METHOD AND APPARATUS FOR RECEIVING IN BEAM SPACE MULTIPLE INPUT MULTIPLE OUTPUT SYSTEM

The present invention relates to a receiving method and apparatus in a beam spatial multiple input multiple output (MIMO) system.

Recently, various communication technologies have adopted the MIMO technique. The MIMO technique is an inevitable method for increasing the data rate, and the effect of maximizing frequency efficiency can be expected. As a representative example, the MIMO technique standardizes the use of the MIMO technique in the IEEE 802.16, 802.20, and Wibro standards of the portable Internet system, and is also used in a cellular communication system called Long Term Evolution (LTE) of the 3rd Generation Partnership Project (3GPP). MIMO technique was adopted.

Transmission performance in such a MIMO communication system generally increases in proportion to the number of antennas. Therefore, in order to maximize MIMO performance, the number of antennas needs to be increased, and accordingly, the number of RF (radio frequency) chains for signal processing increases as much as the number of antennas. However, as the number of antennas increases, implementation complexity increases and the size of the system increases, so that the number of antennas cannot be increased arbitrarily. In order to overcome this limitation, research to achieve MIMO performance using one or a small number of RF chains is being conducted recently. As a representative example, a beam using an ESPAR (Electrical Steering Parasitic Array Radiator) antenna or a Load Modulation Antenna There is spatial MIMO technology.

Compared to the existing MIMO technology, the beam space MIMO technology takes a slightly different form in terms of antenna/RF and baseband. Unlike the existing beam space MIMO, since there is only one RF chain, it is impossible to receive multiple signals at the same time. Therefore, the beam space MIMO receiver appropriately adjusts the load value in the baseband, rotates the beam basis pattern omnidirectionally according to time within one symbol period, and scans each beam basis pattern to add to the MIMO signal. get information about The ADC sampling frequency is changed according to the number of beam basis patterns, and the ADC sampling frequency depends on the number of beam basis patterns. In this case, the length of one symbol interval is constant. Therefore, the beam space MIMO receiver operates in a manner in which the number of samples of each beam base pattern is kept constant by changing the ADC sampling frequency. That is, if the number of beam base patterns scanned in one symbol period increases, the ADC sampling frequency increases, and the time interval occupied by one beam base pattern in the symbol period becomes shorter, thereby reducing the SNR. Accordingly, when many streams are received, the SNR is structurally reduced, and only very few streams can be received at the same time, so that the advantage of MIMO is largely lost. Therefore, there is a need for a receiving method capable of reducing such performance degradation to a minimum.

SUMMARY OF THE INVENTION An object of the present invention is to provide a receiving method and apparatus in a beam space MIMO system capable of maximally reducing a decrease in SNR according to the number of rotating beam base patterns for MIMO communication in a beam space MIMO system.

According to an embodiment of the present invention, there is provided a receiving method in a receiving apparatus of a beam space multiple input multiple output (MIMO) system. A receiving method of a beam spatial MIMO system includes the steps of sequentially forming beams corresponding to all beam base patterns during a corresponding one symbol period to perform full beam scanning and communication when a set event occurs, and the full beam scanning and and performing effective beam communication by reducing the number of beam base patterns used for MIMO communication by using the result of performing the entire beam scanning and communication in the remaining symbol periods except for the symbol period for performing communication.

According to an embodiment of the present invention, SNR degradation caused by performing full rotation in every symbol period in a beam space MIMO system is prevented as much as possible, and accordingly, a channel capable of guaranteeing good SNR to a receiving device is provided. The effect of maximally improving MIMO performance can be expected.

1 is a diagram illustrating an example of a receiving apparatus of a beam space MIMO system according to an embodiment of the present invention.
2 is a diagram illustrating an example of a beam space MIMO reception method according to an embodiment of the present invention.
3 is a diagram illustrating another example of a beam spatial MIMO reception method according to an embodiment of the present invention.
4 is a diagram illustrating an example of a method for performing full beam scanning and communication according to an embodiment of the present invention.
5 and 6 are views each showing an example of a method of reducing the number of beam base patterns according to an embodiment of the present invention.
7 and 8 are diagrams illustrating an example of a method for performing effective beam communication, respectively.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification and claims, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

A receiving method and apparatus in a beam space MIMO system according to an embodiment of the present invention will now be described in detail with reference to the drawings.

1 is a diagram illustrating an example of a receiving apparatus of a beam space MIMO system according to an embodiment of the present invention.

The receiving apparatus 100 of the beam space MIMO system includes an antenna array 110 , a single RF chain 120 , a baseband processing unit 130 , and a load calculation unit 140 .

The antenna array 110 receives a signal transmitted in the beam space by the transmitting apparatus of the beam space MIMO system. The antenna array 110 may include one active antenna element and a plurality of parasitic antenna elements. The transmitting apparatus of the beam space MIMO system maps data symbols to each beam base pattern in the beam space during one symbol period and transmits them through one RF chain. The transmitting apparatus uses beam base patterns orthogonal in beam space.

The antenna array 110 forms a beam having a beam base pattern corresponding to the control of the load calculator 140 , and receives a signal through the formed beam. The antenna array 110 may be implemented through Electrical Steering Parasitic Array Radiation (ESPAR), Switched Parasitic Array (SPA), Load Modulation Antenna, etc., and may have a different structure to implement beam space MIMO. have.

The single RF chain unit 120 includes one or fewer RF chains than the number of antennas in the antenna array 110 , and converts an RF band signal received through the antenna array 110 into a baseband signal. Specifically, the single RF chain unit 120 converts an analog signal into a baseband digital signal according to the ADC sampling frequency. The single RF chain unit 120 may change the ADC sampling frequency according to the ADC sampling frequency control of the load calculator 140 . The baseband processing unit 130 processes the baseband signal to extract data. The baseband processing unit 130 includes a plurality of buffers 132 ₁ to 132 _n and a control unit 134 . where n is the number of beam base patterns. Each of the buffers 132 ₁ to 132 _n stores the received signal of the corresponding beam base pattern. The controller 134 determines the number of valid beam basis patterns based on a received signal corresponding to the beam basis patterns. The control unit 134 transmits information on the effective beam basis pattern to the load calculation unit 140 so that effective beam communication can be performed later.

The load calculator 140 calculates a load value for each antenna element (parasitic antenna element) included in the antenna array 110 using the baseband signal, and calculates a load value for each antenna element (parasitic antenna element). Therefore, each antenna element is controlled.

When a specific event occurs, the load calculator 140 may control the antenna array 110 to sequentially form beams corresponding to all beam base patterns during a corresponding one symbol period. An operation of receiving a signal by sequentially forming beams corresponding to the entire beam base pattern during one symbol period is called “full beam scanning and communication”.

In general, a channel viewed by the receiving device 100 may not maintain a full rank and a good condition number in many cases. In addition, it is common that the channel environment does not change rapidly for a short time. Therefore, it may be a waste of resources to perform full beam scanning and communication operations during every symbol period like the reception apparatus of the existing beam space MIMO system. In addition, there is a method for determining which beam base pattern is meaningful through analysis of a received signal when the entire beam scanning and communication operation is performed once from the viewpoint of the terminal. Accordingly, the load calculator 140 does not perform full beam scanning and communication in every symbol interval, but performs full beam scanning and communication only when a specific event occurs. The specific event may include a command of a base station or a higher layer or a set full beam scanning and communication period. A command of the base station or an upper layer may be transmitted in a situation where it is necessary to search for a channel again, such as cell search and power-on.

In addition, the load calculator 140 reduces the number of beam base patterns to be used based on a result of performing full beam scanning and communication in a symbol section in which full beam scanning and communication are not performed, so that effective beam communication can be performed. Here, the effective beam communication refers to an operation of receiving a signal by forming beams corresponding to a number of beam basis patterns less than the total number of beam basis patterns during one symbol period. At this time, it should be possible to change the ADC sampling frequency of the single RF chain unit 120 according to the number of effective beam base patterns. That is, the ADC sampling frequency of the symbol section performing full beam scanning and communication and the ADC sampling frequency of the symbol section performing effective beam communication may be different from each other. It is set below the ADC sampling frequency of the symbol section performing scanning and communication. The load calculator 140 receives information on an effective beam base pattern from the baseband processor 130 and controls the ADC sampling frequency.

As described above, by reducing the number of beam base patterns used for MIMO communication through effective beam communication, it is possible to prevent SNR degradation as much as possible.

2 is a diagram illustrating an example of a beam space MIMO reception method according to an embodiment of the present invention.

Referring to FIG. 2 , upon receiving the full scanning command, the load calculator 140 performs full beam scanning and communication for one symbol period Ts, and scans the entire beam during the remaining symbol period Ts. The antenna array 110 is controlled so that effective beam communication for performing MIMO communication can be performed using only valid beams without doing so.

When the load calculation unit 140 receives the full scanning command from the base station or the upper layer, it can immediately control the antenna array 110 to perform full beam scanning and communication during the corresponding symbol period (Ts). The antenna array 110 may be controlled to perform full-beam scanning and communication in any one symbol period Ts with a specific difference.

3 is a diagram illustrating another example of a beam scanning method according to an embodiment of the present invention.

As shown in FIG. 3 , the load calculator 140 controls the antenna array 110 to perform full beam scanning and communication during one symbol period Ts according to the set full beam scanning and communication period, and the remaining During the symbol period, the antenna array 110 may be controlled to perform effective beam communication.

In addition, the load calculator 140 may control the antenna array 110 to perform full beam scanning and communication during one symbol period (Ts) when the entire beam scanning and communication period is reached, and within the entire beam scanning and communication period When a full scanning command is received from , full beam scanning and communication can be performed again during one symbol period (Ts).

4 is a diagram illustrating an example of a method for performing full beam scanning and communication according to an embodiment of the present invention.

Referring to FIG. 4 , when the number of all beam basis patterns (0, 1, 2, 3) is four, the load calculator 140 divides one symbol period Ts into four slot periods S1, S2, S3, S4), and controls the antenna array 110 to form a beam base pattern (0, 1, 2, 3) in the slot sections (S1, S2, S3, S4), respectively.

5 and 6 are views each showing an example of a method of reducing the number of beam base patterns according to an embodiment of the present invention.

Referring to FIG. 5 , the load calculation unit 140 does not use and discards a beam basis pattern that does not satisfy a specific criterion among all beam basis patterns 0, 1, 2, and 3 . For example, when the beam base pattern 3 from among the four beam base patterns 0, 1, 2, and 3 does not satisfy a specific criterion, the load calculation unit 140 sets the three beam base patterns 0, 1 , 2) can only be used.

Also, referring to FIG. 6 , the load calculation unit 140 may use a beam base pattern that does not satisfy a specific criterion among all the beam base patterns 0, 1, 2, and 3 in combination with other beam base patterns. For example, when the beam base pattern 3 among the four beam base patterns 0, 1, 2, and 3 does not satisfy a specific criterion, the load calculation unit 140 sets the beam base pattern 3 as the beam base. A beam base pattern (0') integrated into the pattern (0) may be formed, and the beam base patterns (0', 1, 2) may be used.

In this case, the baseband processing unit 130 may determine a beam base pattern that does not satisfy a specific criterion among all the beam base patterns 0, 1, 2, and 3 .

The baseband processing unit 130 may set various criteria necessary for reducing the beam base pattern. For example, the reference may be set to be a beam basis pattern in which the magnitude (strength) of a received reference signal or S(I)NR is equal to or greater than a set threshold value. The transmitting apparatus transmits the reference signal through each of the beam base patterns used in the beam space. The reference signal may include identification information of the beam base pattern. The baseband processing unit 130 measures the magnitude (strength) or S(I)NR of the received reference signal, compares whether the magnitude (strength) or S(I)NR of the received reference signal is greater than or equal to a set threshold value. A beam basis pattern that does not satisfy the criterion may be determined. The load calculation unit 140 may not use a beam base pattern that does not satisfy the criterion or may integrate it with another beam base pattern.

Also, for example, the criterion is that the magnitude (strength) or S(I)NR of the received reference signal is greater than or equal to a set threshold, and the S(I)NR of the reference signal is a beam base pattern corresponding to the highest set number. can be set. In this way, even if the magnitude (strength) or S(I)NR of the received reference signal is greater than or equal to a set threshold, only the beam base pattern having a good S(I)NR is excluded from the beam base pattern having a poor S(I)NR. It can be used, and the S(I)NR deviation of the beam basis pattern used can be reduced, and a good channel condition coefficient can be obtained. As described above, according to the effect of reducing the number of beam basis patterns, there is an effect that the overall S(I)NR increases and the average S(I)NR increases while the beam basis patterns with bad S(I)NR are excluded.

In this case, as the number of used beam base patterns decreases, the remaining time for scanning can be divided among the used beam base patterns.

7 and 8 are diagrams illustrating an example of a method for performing effective beam communication, respectively.

Referring to FIG. 7 , when only three beam basis patterns (0, 1, 2) are used among the four beam basis patterns (0, 1, 2, 3), the load calculation unit 140 calculates the beam basis pattern (3). ) is equally divided into the slot section [S4(3)] for scanning the three beam base patterns (0, 1, 2) into the slot section [S1(0), S2(1), S3(2)] can give Accordingly, the slot period [S1(0), S2(1), S3(2)] for scanning the beam base pattern 0, 1, 2 becomes longer.

On the other hand, referring to FIG. 8 , the load calculation unit 140 assigns appropriate weights to the used beam base patterns 0, 1, and 2 in an order that satisfies a specific criterion, and scans the beam base pattern 3 . The slot section [S4(3)] may be divided according to the weights set in the beam base pattern (0, 1, 2). For example, only the slot section [S1(0)] in which the beam base pattern 0 is scanned according to the weights set in the beam base pattern (0, 1, 2) is the slot section [S4] in which the beam base pattern 3 is scanned. (3)] can be increased. At this time, the slot section [S4(3)] for scanning the beam base pattern 3 in proportion to or inversely proportional to the weight set in the beam base pattern (0, 1, 2) is used for scanning the beam base pattern (0, 1, 2). It may be divided into at least one of the slot sections [S1(0), S2(1), S3(2)].

The embodiment of the present invention is not implemented only through the apparatus and/or method described above, and a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium in which the program is recorded may be implemented, Such an implementation can be easily implemented by an expert in the technical field to which the present invention pertains from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the right.

Claims (10)

A communication method in a communication device of a beam space multiple input multiple output (MIMO) system, comprising:
When a set event occurs, performing full-beam scanning and communication by sequentially forming a beam corresponding to the entire beam base pattern in an omnidirectional direction during a corresponding one symbol period, and
In the remaining symbol sections except for the symbol section in which the full beam scanning and communication are performed, an effective beam base pattern to be used for communication is determined using the result of performing the full beam scanning and communication, and a beam corresponding to the effective beam base pattern is selected. Forming sequentially in all directions to perform effective beam communication
including,
The step of performing the full beam scanning and communication and the step of performing the effective beam communication are each
determining a sampling frequency in a corresponding symbol interval according to the number of used beam base patterns; and
and converting an analog signal received through an antenna array into a digital signal according to the sampling frequency. In claim 1,
The step of performing the effective beam communication is
determining a beam basis pattern that does not satisfy a set criterion among all the beam basis patterns; and
and discarding a beam base pattern that does not satisfy the set criteria or integrating it with another beam base pattern. In claim 2,
The step of determining the beam base pattern that does not satisfy the set criteria is
receiving a reference signal transmitted through each of the full beam basis patterns; and
and determining a beam basis pattern that does not satisfy the set criterion based on the signal quality of the reference signal. In claim 1,
The performing of the effective beam communication includes increasing a scanning period of at least one beam basis pattern among the beam basis patterns used for the communication by a scanning period of the reduced beam basis pattern. delete A communication device for a beam space Multiple Input Multiple Output (MIMO) system, comprising:
An antenna array for transmitting and receiving signals by forming a beam of at least one beam base pattern;
A signal corresponding to each beam base pattern transmitted and received through the antenna array is processed, and the number of beam base patterns to be used is reduced through a reference set from signals corresponding to all beam base patterns transmitted and received through the antenna array, thereby reducing the effective beam base pattern. a baseband processing unit that determines the pattern;
Controls the antenna array to perform full-beam scanning and communication by sequentially forming beams corresponding to the entire beam base pattern during one symbol period of a set period, except for a symbol period in which the entire beam scanning and communication are performed In the remaining symbol period, a load calculation unit for controlling the antenna array to form a beam corresponding to the effective beam basis pattern to perform effective beam communication, and
A single radio frequency (RF) chain unit that converts a signal received through the antenna array into a baseband signal according to a sampling frequency
including,
The load calculator determines the sampling frequency according to the number of beam base patterns to be used for the full beam scanning and communication and the effective beam communication. In claim 6,
The baseband processing unit determines a beam base pattern that does not satisfy the set criteria from among all the beam base patterns, and discards the beam base patterns that do not satisfy the set criteria from among all the beam base patterns or satisfies the set criteria. A communication apparatus for a beam space MIMO system that determines the effective beam base pattern by integrating a non-functional beam base pattern with another beam base pattern. In claim 6,
The load calculator additionally allocates a scanning period of the reduced beam basis pattern to a scanning period of at least one beam basis pattern among the effective beam basis patterns in each of the remaining symbol periods. delete In claim 6,
wherein the antenna array includes one active antenna element and at least one parasitic antenna element.

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