KR101703371B1 - Receiver for receiving data frame transmitted from transmitter in mimo system and method thereof - Google Patents

Abstract

A receiving terminal for receiving a data frame transmitted from a transmitting terminal in a MIMO system and an operating method of the receiving terminal are disclosed. One embodiment receives a signal field repeatedly transmitted according to a frequency band applied to transmission of a data frame, sets a signal field based on a repetition pattern of the signal field, estimates a channel based on the hard-decision result , Soft decision of the signal field, combining soft decisions based on the repeat pattern, and decoding the signal field based on the result of the combination.

Description

TECHNICAL FIELD [0001] The present invention relates to a receiving terminal for receiving a data frame transmitted from a transmitting terminal in a MIMO system, and an operation method of the receiving terminal. [0002]

The present invention relates to a method and apparatus for receiving a data frame transmitted from a transmitting terminal in a MIMO system, and more particularly to a method and apparatus for efficiently using a signal field for each user in a MIMO and a wireless communication system using a variable frequency band. And to a method and apparatus for receiving data.

A wireless LAN is basically an access point (AP) serving as an access point of a distribution system (DS) and a basic service set (APS) composed of a plurality of wireless terminals (STA) (BSS) mode or an independent BSS (IBSS) mode which is composed only of a STA. (Hereinafter, AP and STA will collectively be referred to as " terminal ").

In a wireless communication system using multiple antennas, that is, a multiple input multiple output (MIMO) system, channel capacity increases with an increase in the number of antennas, thereby increasing frequency efficiency. The MIMO system can be classified into two types as follows. The first is SU-MIMO, which transmits multiple streams only to a single user. The second is MU-MIMO, which transmits multiple streams to multiple users by eliminating interference between users in the AP.

The MU-MIMO has an advantage that the multi-user diversity gain can be obtained as the channel capacity increases. In addition, the MU-MIMO scheme can transmit multiple streams to multiple users at the same time using the same frequency band, thereby increasing the throughput as compared with the conventional communication scheme. In general, although the throughput of the wireless communication system can be increased by increasing the frequency band, there is a disadvantage that the system cost increases as the frequency band increases. On the other hand, although the MU-MIMO scheme does not increase the frequency band, the complexity increases greatly compared to the existing communication scheme. Accordingly, standards such as 802.11ac adopts a method of simultaneously applying MU-MIMO technology while using a variable frequency depending on the surrounding situation.

In a wireless communication system that transmits a multi-antenna stream to a plurality of users at the same time using a variable frequency band, a signal field including information about the corresponding data field is transmitted along with the data field. The signal field is divided into two types as follows. The first is a common signal field that contains information that is commonly applied to users. The second is a dedicated signal field that contains information applied to each user. The common signal field can be recognized by all users belonging to or belonging to the common user group. In addition, the common signal field should be compatible because it is used for auto-detection to determine which communication frame the transmitted data frame was generated by. Therefore, there are restrictions on changing the format or configuration of the common signal field.

These common signal fields are transmitted via a simple repetition scheme for SNR gain and frequency diversity gain. However, since the dedicated signal field includes only user-specific information, it can have a more various structure.

For example, the IEEE 802.11ac VHT-SIG B has a structure as shown in FIG.

In case of using 20MHz band, VHT has 52 data tones and has 108 data tone in 40MHz band, 234 data tone in 80MHz band, and 234x2 data tone in 160MHz band. The legacy signal field is repeatedly transmitted in units of 20 MHz after modulation, whereas the VHT-SIG B is repeatedly encoded as described above before the encoder is input, and is then interleaved and then transmitted.

Therefore, there is a need for a technique for improving the performance of the receiver by efficiently using the repeating structure of the VHT-SIG B portion in view of the above points.

Embodiments provide a method and apparatus for improving the performance of a receiver by more efficiently utilizing a signal field transmitted together when a transmitting terminal transmits data to a receiving terminal in a MIMO system.

Herein, the objects of the embodiments are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description and can be understood more clearly by the embodiments of the present invention will be. It is also to be easily understood that the objects and advantages of the embodiments can be realized by the means shown in the claims and their combinations.

An operation method of a receiving terminal that receives a data frame transmitted from a transmitting terminal in a MIMO system according to one side includes receiving a pilot field for channel estimation between the transmitting terminal and the receiving terminal; Receiving a signal field repeatedly transmitted according to a frequency band applied to transmission of the data frame; Hard decision of the signal field based on a repetition pattern of the signal field; Estimating a channel based on the pilot field and the hard-decision result; Soft decision of the signal field; Combining the soft decisions results based on the repeated pattern; And decoding the signal field based on the result of the combining.

In this case, the step of determining the signal field includes extracting mutually corresponding repetition signals included in the signal field based on the repetition pattern of the signal field. Combining the extracted repetitive signals; And hardening the combined signal.

In addition, the step of determining the combined signal comprises: determining the strength of the combined signal; And determining whether to estimate the channel based on the hard-decision result according to the determined strength.

The estimating of the channel may include calculating an average value of the pilot field and the hard decision result; And estimating a channel for data symbols included in the data frame using the calculated average value.

In addition, the data frame may conform to the IEEE 802.11ac standard.

In addition, the signal field may include a VHT-SIG B field defined in the IEEE 802.11ac standard.

In addition, the pilot field may include a VHT-LTF field defined in the IEEE 802.11ac standard.

1 is a diagram for explaining a structure of an IEEE 802.11ac VHT-SIG B according to an embodiment;
2 is a flowchart illustrating an operation method of a receiving terminal that receives a data frame transmitted from a transmitting terminal in a MIMO system according to an exemplary embodiment.
FIG. 3 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using a 40 MHz band; FIG.
FIG. 4 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using an 80 MHz band; FIG.
FIG. 5 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using a 160 MHz band; FIG.

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

2 is a flowchart illustrating an operation method of a receiving terminal that receives a data frame transmitted from a transmitting terminal in a MIMO system according to an exemplary embodiment.

Referring to FIG. 2, in a MIMO system using a variable frequency band according to an exemplary embodiment, a method for transmitting and receiving data to and from a receiving terminal includes transmitting a signal repeatedly transmitted according to a frequency band applied to transmission of a data frame, Determining a size of the corresponding tone in the field, performing BPSK hard decision using the repeated pattern after size determination, combining the hard decision signal with the training field, using the combined signal Performing soft decision on the bits of the signal field, and combining the soft decision LLR values using a repetition pattern.

In order to explain these steps, the VHT 40 MHz band according to an embodiment will be described in detail below. The VHT 20, 80, and 160 MHz bands according to other embodiments are also applicable in the same manner.

FIG. 3 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using a 40 MHz band.

According to one embodiment, when VHT-SIG B is transmitted using the 40 MHz band, the codeword bits may be filled in the interleaver stage as shown in FIG.

More specifically, the 27-bit data bits including the tail bit are hatched using the 1/2 coding rate after repeating twice, resulting in 108 bits. In this case, the codeword is also repeated in units of 54 bits. At this time, the interleaver stages can perform interleaving in the order of writing in rows and reading in rows.

For example, the transmitted bits may be BPSK mapped to a frequency tone in the order of 0, 18, 36, 0, 18, 36, ..., 17, 35, 53, 17, 35,

A receiving terminal according to an exemplary embodiment can provide a technique for improving efficiency at a receiving end using the characteristics of the transmitting end.

In the receiver, it is possible to increase the hard decision reliability of the BPSK signal by separating the repeatedly transmitted frequency tones and receiving the received signals in combination. For example, in FIG. 3, it is possible to improve the hard decision reliability by combining two BPSK signals corresponding to the 0th codeword (for example, using a reception technique such as MRC) and performing hard decision on the combined result .

The receiving terminal according to an embodiment can obtain the channel estimation gain by combining the hard-decision BPSK signals with the VHT-LTF transmitted before VHT-SIG B.

However, although two BPSK signals are combined to improve reliability, both of them can be received through a channel having a relatively low reliability due to fading. Therefore, the receiving terminal according to another embodiment can determine whether to use the hard decision signal for channel estimation enhancement by performing the step of determining the size of the channel.

If it is determined that the hard decision signal is to be used for channel estimation, the receiving terminal multiplies the hard decision signal of VHT-LTF signal and hard decision signal of VHT-SIG B by +1 or -1, adds the signal to the average, And can be used as a channel estimation value of VHT-DATA symbols transmitted from the VHT-SIG B signal.

As a result, the receiving terminal according to one embodiment can have channel estimation performance such as channel estimation using two LTFs (e.g., VHT-LTF and hard decision signal).

Also, the receiving terminal according to an exemplary embodiment may improve the reliability of the decoding result of the VHT-SIG B signal by using the soft decision result of the two repeated BPSK signals to increase the reliability of the LLR value of the input signal of the decoder .

Therefore, the receiving terminal according to the embodiments can provide a technique of not only improving the decoding performance of the VHT-SIG B signal field, but also improving the reliability of the repeated VHT-SIG B signal. As the hard decision reliability of the VHT-SIG B signal increases, the effect of improving the channel estimation of the VHT-DATA also increases, so that the receiving terminal can provide a technique for enabling efficient reception.

FIG. 4 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using an 80 MHz band.

According to one embodiment, when VHT-SIG B is transmitted using the 80 MHz band, the codeword bits may be filled in the interleaver stage as shown in FIG.

In this case, the schemes described with reference to FIG. 3 can be directly extended.

For example, since there are four repeated signals in the case of the 80 MHz band, the receiving terminal according to the embodiment can be applied as in the case of using the 40 MHz band by combining four signals at the receiving end. In this case, since the four signals are combined, the reliability can be further improved.

5 is a diagram for explaining a repetition pattern of VHG-SIG B when VHT-SIG B according to an embodiment is transmitted using a 160 MHz band.

According to one embodiment, when VHT-SIG B is transmitted using the 160 MHz band, the codeword bits may be filled in the interleaver stage as shown in FIG.

In this case, the schemes described with reference to FIG. 3 can be directly extended.

For example, since there are eight repeated signals in the case of the 160 MHz band, the receiving terminal according to the embodiment can be applied as in the case of using the 40 MHz band by combining eight signals at the receiving end. In this case, since the eight signals are combined, the reliability can be further improved.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (7)

A method of operating a receiving terminal for receiving a data frame transmitted from a transmitting terminal in a MIMO system,
Receiving a pilot field for channel estimation between the transmitting terminal and the receiving terminal;
Receiving a signal field repeatedly transmitted according to a frequency band applied to transmission of the data frame;
Hard decision of the signal field based on a repetition pattern of the signal field;
Estimating a channel based on the pilot field and the hard-decision result;
Soft decision of the signal field;
Combining the soft decisions results based on the repeated pattern; And
Decoding the signal field based on the result of the combining
Lt; / RTI >
The step of determining the signal field comprises:
Extracting mutually corresponding repetition signals included in the signal field based on the repetition pattern of the signal field;
Combining the extracted repetitive signals; And
The step of determining the combined signal
The method comprising the steps of:
delete The method according to claim 1,
The step of determining the combined signal comprises:
Determining the strength of the combined signal; And
Determining whether to estimate a channel based on the hard-decision result according to the determined strength
≪ / RTI >
A method of operating a receiving terminal.
The method according to claim 1,
Estimating the channel comprises:
Calculating an average value of the pilot field and the hard-decision result; And
Estimating a channel for data symbols included in the data frame using the calculated average value;
/ RTI >
A method of operating a receiving terminal.
The method according to claim 1,
Wherein the data frame conforms to the IEEE 802.11ac standard,
A method of operating a receiving terminal.
The method according to claim 1,
The signal field includes a VHT-SIG B field defined in the IEEE 802.11ac standard.
A method of operating a receiving terminal.
The method according to claim 1,
The pilot field includes a VHT-LTF field defined in the IEEE 802.11ac standard.
A method of operating a receiving terminal.

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