KR100945491B1 - Method and apparatus for generating data frame in Wireless Personal Area Network - Google Patents

Abstract

The present invention relates to a method for generating a data frame for use in a WPAN, and according to the present invention, the data frame includes a plurality of subframes, each subframe including an FCS for detecting an error, and the transmitting device Since only the subframes generated by E can be selectively retransmitted, and the subframes to be retransmitted can be actively determined according to the importance, the WPAN can efficiently utilize the limited channel time.

Description

Method and apparatus for generating data frame in JPAN {Method and apparatus for generating data frame in Wireless Personal Area Network}

The present invention relates to a WPAN, and more particularly, to a method for generating a data frame used in the WPAN.

WPAN is a network that provides wireless connectivity in a relatively short personal operating space, such as a home or office. In WPAN, devices communicate in a TDMA manner in a piconet that has a range of about 10m and forms an ad hoc network.

The IEEE 802.15 Working Group (WG) was created to provide a communication standard in the Personal Operating Space, and among the four TGs (Task Group) belonging to the IEEE 802.15 WG, IEEE 802.15.3 provides high-speed data. The standardization of HR (High Rate) -WPAN for transmission is completed.

1 is a diagram illustrating a structure of a general data frame used in a WPAN.

The preamble 110 is a field in which patterns for packet detection, symbol synchronization, frequency synchronization, and the like are recorded.

The PHY header 120 is a field in which information on the length of the frame body, the data rate of the frame body, and the like is recorded. The PHY header 120 is a header of the physical layer, and the MAC header 130 is a header used in the MAC layer.

The MAC Service Data Unit (MSDU) 140 is data that the MAC layer receives from the upper layer, and is a part of the payload of the MAC Protocol Data Unit (MPDU) delivered to the PHY layer through the service of the MAC layer.

The frame check sequence (FCS) 150 is a field in which a cyclic redundancy check (CRC) code is recorded so that a reception side can detect such an error when an error due to transmission occurs in a data frame.

A more detailed description of the data frame used in the WPAN is described in the IEEE 802.15.3 HR-WPAN standard and so on, and will be omitted here.

In the WPAN, when the receiving device receives a data frame as shown in FIG. 1 from the transmitting device, an error is detected using the FCS. If there is no error, the receiving device sends an ACK to the transmitting device to indicate that the data frame has been received without error.

As described above, according to the related art, when an error occurs in any part of the MSDU 140, the receiving device does not transmit the ACK for the corresponding data frame, and thus the transmitting device must retransmit the entire data frame, thereby reducing bandwidth and resources. There is a problem of being used inefficiently. In a TDMA WPAN, this retransmission process can be fatal to QoS, especially if the entire data frame is retransmitted in the event that an error occurs that is less important than other data and can be ignored. There is a problem to use.

An object of the present invention is to provide an apparatus and method for generating a data frame to efficiently use the channel time allocated to a device in WPAN.

According to an aspect of the present invention, there is provided a method of generating a data frame used in a WPAN, the method comprising: generating a plurality of subframes using at least one MSDU; Generating a sub-header including information on the corresponding sub-frame for each of the sub-frames; And generating a PSDU using the subframes, the subheaders, and the MAC header, wherein each of the subframes has an FCS field for detecting an error of a corresponding subframe.

The generating of the subframes may include a subframe including only first type bits and only second type bits using first type bits and second type bits extracted from the at least one MSDU. A subframe including a subframe and all of the first type bits and the second type bits is generated, and the subheaders include a field indicating which bits the subframe consists of.

A subframe including both first type bits and second type bits of the subframes may include separate fields in which FCSs for detecting an error are independently recorded for the first type bits and the second type bits. It is preferable to include.

The PSDU generating step may include generating a CRC code for detecting an error of the sub headers; And combining the subframes, the subheaders, and the CRC code with a MAC header.

The sub headers preferably include a field indicating whether to request an independent ACK for the first type bits and the second type bits of the corresponding subframe.

The data frame generation method may further include generating a PPDU by applying an MCS for a PHY header, the subheaders, and the MAC header, which has a lower data rate than the subframes.

The subheaders are fields in which an identifier of a corresponding MSDU is recorded when a subframe is one of fragments and a field in which information on the order of the subframes in the subdivisions of a corresponding MSDU is recorded. It is preferable to include.

The data frame generation method may further include generating a PHY header including a field indicating whether the sub-headers are included in the data frame.

The data frame generation method may include generating a CRC code for detecting an error of a preamble, a PHY header, and the MAC header; And generating a PPDU using the CRC code and the PSDU.

The sub headers preferably include a field in which information on an MCS applied to a corresponding sub frame is recorded.

The present invention also provides a recording medium on which a computer program for executing the data frame generation method is recorded.

In addition, the present invention provides an apparatus for generating a data frame used in the WPAN, the apparatus comprising: a subframe generation unit for generating a plurality of subframes using at least one MSDU; A subheader generator configured to generate a subheader including information on a corresponding subframe for each of the subframes; And a PSDU generation unit for generating a PSDU using the subframes and the subheaders and the MAC header, wherein each of the subframes has an FCS field for detecting an error of the subframe.

According to the present invention, the transmitting device of the WPAN may selectively retransmit only a subframe in which an error occurs among a plurality of subframes included in one data frame.

In addition, when the data is uncompressed, each subframe may have different importance, and thus, the transmitting device may actively use a limited channel time by actively determining a subframe to be retransmitted according to a situation. Furthermore, even when there are relatively important data and less important data in one subframe, the FCS is recorded for each of them, so that an error can be independently detected for each of them at the receiving side.

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

2 is a diagram illustrating a process of generating a data frame according to an embodiment of the present invention.

In operation 201, a plurality of subframes are generated through fragmentation or aggregation of a MAC Service Data Unit (MSDU). That is, several subframes may be generated from one MSDU, or one subframe may be generated by merging several MSDUs.

If the MSDU is data compressed through a compression algorithm such as MPEG or JPEG, all bits will have the same importance. If uncompressed data such as RGB data, the information contained in each bit will have different importance. For example, in the case of RGB data, the upper four bits of one byte generally have more important information than the lower four bits. Hereinafter, the bits that are relatively important in each byte of the MSDU are referred to as More Significant Bits (MSB) and less significant bits as LSBs (Less Significant Bits). How many bits from one byte become the MSB may vary depending on the type of data and the implementation. However, all bits other than the MSB in one byte become LSBs.

In step 201, when generating subframes, it is preferable to generate a subframe including only the MSB, a subframe consisting only of the LSB, and a subframe including both the MSB and the LSB. That is, three types of subframes are generated. In this case, since the importance between subframes is different, when an error occurs in a subframe, the transmitter can determine which subframe to selectively retransmit and use the channel time efficiently.

In step 202, an FCS is recorded in each of the subframes. That is, according to the present invention, since each subframe has a separate FCS field, even when one data frame is transmitted, the receiving side can specifically detect in which subframe an error has occurred, If the subframe is notified that an error has occurred, the transmitting side can retransmit only the subframe in which the error has occurred, so that the channel time can be used efficiently.

In step 203, subheaders for subframes are generated. Information about subframes is recorded in the subheaders. A more detailed description of the sub header will be described later with reference to FIG. 3.

In step 204, a cyclic redundancy check (CRC) code for error detection of sub-headers is generated. If an error occurs in the subheaders, the receiver cannot decode the subframes to obtain the correct data. Therefore, first check whether there is an error in the subheaders. If an error occurs, the receiver does not decode the remaining parts at all. It is to save time and resources.

In step 205, generate a MAC header, a PHY header and a preamble.

In step 206, a CRC code for error detection of the MAC header, the PHY header and the preamble is generated. If an error occurs in these headers, it is to save time and resources by not decoding the remaining parts at the receiving side.

Meanwhile, when delivering the MPDU (= PSDU) from the MAC layer to the PHY layer, a Modulation and Coding Scheme (MCS) for the data frame is determined, and the PHY layer performs modulation and coding accordingly, and according to the MCS, the data rate ( Data Rate) is different. In general, the lower the data rate, the lower the probability of error. Therefore, the MAC header, the PHY header, the preamble, and the subheaders are preferably applied to the MCS, which yields a lower data rate than the subframes.

3 is a diagram showing the structure of a data frame according to an embodiment of the present invention.

As shown in FIG. 3, a data frame according to an embodiment of the present invention may include a preamble 301, a PHY header 302, a MAC header 304, an HCS1 305, subheaders 306, and an HCS2 ( 307, subframes 308.

The PHY header 302 includes a subheader flag 303 that indicates whether or not the subheaders 306 are included in the data frame.

The HCS1 305 is a field in which a header check sequence (HCS), which is a CRC code for detecting an error of the preamble 301, the PHY header 302, and the MAC header 304, is recorded, and the HCS2 307 is a subheader. A field in which an HCS which is a CRC code for detecting an error of 306 is recorded.

Meanwhile, the sub header 311 constituting the sub headers 306 includes the MCS Information field 321, the FCS Information field 322, the Subframe information field 323, the UEP ACK Request field 324, and the MSDU Number field ( 325, a Fragmentation Information field 326, a Subframe length field 327, and a reservation field 328.

The MCS Information field 321 includes information indicating which MCS is applied to a data frame. This information can be an index pointing to a specific MCS, and WPAN devices must have a table that matches the index and MCS in advance. An example of such a table is shown in FIG. 4.

In the FCS Information field 322, information indicating whether the FCS is included in the corresponding subframe is recorded. When the FCS information is set to 1, if the subframe includes both the MSB and the LSB, the subframe includes separate FCSs capable of independently detecting errors for the MSB and the LSB.

In the subframe information field 323, information indicating which bits the subframe consists of is recorded. That is, as described above, since the subframe is generated using the MSB and the LSB extracted from the MSDU, it indicates whether the corresponding subframe includes only the MSB, only the LSB, or both the MSB and the LSB.

The UEP ACK Request field 324 records information indicating whether to request an ACK according to Unequal Error Protection (UEP). The ACK according to the UEP means that when the corresponding subframe includes both the MSB and the LSB, the receiver notifies whether the error has occurred for each of the MSB and the LSB. By utilizing such a UEP ACK, when an error occurs only in the LSB, the transmitter may adjust QoS by retransmitting another MSB that is more important according to a communication environment without retransmitting the LSB. Such ACK policy related information is generally recorded in the MAC header 304. Therefore, in the present embodiment, this information is assumed to be recorded in the UEP ACK Request field 324 of the sub header 311, but may be recorded in the MAC header 304 according to the implementation.

Meanwhile, when the corresponding subframe is one of fragments of the MSDU, the identifier of the corresponding MSDU is recorded in the MSDU Number field 325, and the order of the corresponding subframe within the fragments in the Fragmentation Information field 326. Information about is recorded. In the present embodiment, 4 bits are allocated to the fragmentation information field 326, and 4 bits may be used to indicate whether the corresponding subframe is the first fragment, the last fragment, or one of the remaining fragments of the MSDU.

Information on the length of the corresponding subframe is recorded in the subframe length field 327, and the reservation field 328 is a field for recording additional information later.

In the present embodiment, as shown in FIG. 3, a specific number of bits is allocated to each field, but it will be apparent to those skilled in the art that the number of bits may vary depending on implementation.

4 is a diagram illustrating an MCS table according to an embodiment of the present invention.

As described above, information on which MCS to apply to the subframe is recorded in the MCS Information field 321.

For example, if 2 (000010) is recorded in the MCS Information field 321, the corresponding subframe is modulated in the 16-QAM scheme and coded in the 2/3 scheme.

If 3 (000011) is recorded in the MCS Information field 321, the corresponding subframe is modulated in the QPSK scheme, and the MSB is coded in the 4/7 scheme and the LSB in the 4/5 scheme. The 4/7 method adds 3 bits of redundancy to 4 bits of input and outputs 7 bits. The 4/5 method adds 1 bit of redundancy to 4 bits of input and outputs 5 bits. . The greater the redundancy, the easier the error correction is. Therefore, in this case, the error correction of the MSB is easier than in the case of the LSB, so that the MSB can be more strongly protected from the error.

5A and 5B illustrate structures of a sub header and a sub frame according to the first embodiment of the present invention.

As shown in FIG. 5A, the subframe according to the present embodiment uses the MCS number 3, uses the FCS, and includes the MSB and the LSB in the subframe, and requests the UEP ACK.

Therefore, at this time, the subframe has a structure as shown in FIG. 5B. That is, since the subframe includes both the MSB and the LSB and uses the FCS, the subframe has both the MSB FCS for error detection of the MSB and the LSB FCS for error detection of the LSB. This subframe is modulated in the QPSK scheme according to No. 3 MCS (see FIG. 4), and the MSB will be coded in 4/7 and LSB in 4/5.

In addition, since the UEP ACK is requested, the receiving side will notify the transmitting side whether or not an error has occurred for each of the MSB and LSB.

6A and 6B illustrate structures of a sub header and a sub frame according to the second embodiment of the present invention.

As shown in FIG. 6A, the subframe according to the present embodiment uses the MCS number 1, uses the FCS, and includes the MSB only in the subframe, and follows the MAC ACK policy without requesting the UEP ACK.

The subframe according to the present embodiment has a structure as shown in FIG. 6B. That is, the subframe includes only the MSB and includes an FCS for error detection of the MSB. This subframe is modulated in the QPSK scheme according to No. 1 MCS (see FIG. 4) and coded in the 2/3 scheme.

In addition, since the UEP ACK is not requested, the receiver processes the ACK process according to the ACK policy included in the MAC header of the data frame.

7A and 7B illustrate structures of a sub header and a sub frame according to the third embodiment of the present invention.

As shown in FIG. 7A, in the subframe according to the present embodiment, the MCS uses No. 0, uses the FCS, and includes only the LSB in the subframe, and follows the MAC ACK policy without requesting the UEP ACK.

The subframe according to the present embodiment has a structure as shown in FIG. 7B. That is, the subframe includes only the LSB and includes an FCS for error detection of the LSB. This subframe is modulated in the QPSK scheme according to the MCS No. 0 (see FIG. 4) and coded in a 1/3 scheme.

In addition, since the UEP ACK is not requested, the receiver processes the ACK process according to the ACK policy included in the MAC header of the data frame.

8A and 8B illustrate structures of a sub header and a sub frame according to the fourth embodiment of the present invention.

As shown in FIG. 8A, the subframe according to the present embodiment uses the MCS no. 2, does not use the FCS, includes only the MSB in the subframe, and follows the MAC ACK policy without requesting the UEP ACK. .

The subframe according to the present embodiment has a structure as shown in FIG. 8B. That is, the subframe consists only of the MSB and does not include the FCS for error detection. This subframe is modulated in the 16-QAM scheme according to No. 2 MCS (see FIG. 4) and coded in the 2/3 scheme.

In addition, since the UEP ACK is not requested, the receiver processes the ACK process according to the ACK policy included in the MAC header of the data frame.

9A and 9B illustrate structures of a sub header and a sub frame according to the fifth embodiment of the present invention.

As shown in FIG. 9A, in the subframe according to the present embodiment, the MCS uses No. 0, does not use the FCS, the LSB is included in the subframe, and follows the MAC ACK policy without requesting the UEP ACK. .

The subframe according to the present embodiment has a structure as shown in FIG. 9B. That is, the subframe includes only the LSB and does not include an FCS for error detection. This subframe is modulated in the QPSK scheme according to the MCS No. 0 (see FIG. 4) and coded in a 1/3 scheme.

In addition, since the UEP ACK is not requested, the receiver processes the ACK process according to the ACK policy included in the MAC header of the data frame.

10 is a diagram showing the structure of an ACK frame according to an embodiment of the present invention.

The ACK frame according to the present embodiment is a case where a transmitting side requests UEP ACK for a plurality of subframes. As shown in FIG. 10, when the ACK frame is used in the present embodiment, the receiving side may notify whether or not an error occurs for a plurality of subframes using one ACK frame. Furthermore, the MSB and the LBS of the subframes can be independently notified of whether an error has occurred, and the transmitting device can more efficiently use the channel time allocated to itself by retransmitting only the failed MSB instead of the LSB having the error. .

11 is a diagram illustrating an apparatus for generating a data frame according to an embodiment of the present invention.

As shown in FIG. 11, an apparatus 1100 (generally a WPAN device) for generating a data frame according to an embodiment of the present invention may include a subframe generator 1101, a subheader generator 1102, and a PSDU generator. A unit 1103, a PHY header generator 1104, a CRC code generator 1105, and a PPDU generator 1106 are included.

The subframe generation unit 1101 generates a plurality of subframes through division or merging of MSDUs.

Specifically, the subframe generation unit 1101 extracts the MSB and the LSB of the MSDU, and generates a subframe including only the MSB, a subframe including only the LSB, and a subframe including both the LSB and the MSB.

At this time, each of the subframes includes an FCS field for detecting an error of the corresponding subframe.

The sub header generating unit 1102 generates sub headers in which information about the sub frames is recorded. This sub-header contains fields as shown in FIG.

The PSDU generation unit 1103 generates a CRC code for detecting an error of the subframes, and combines the subframes, the subheaders and the CRC code with the MAC header to generate a PHY Protocol Service Unit (PSU).

The PHY header generator 1104 generates a PHY header which is a header used in the physical layer. At this time, the PHY header includes a flag indicating whether subheaders are included in the data frame.

The CRC code generator 1104 generates a CRC code for detecting an error of the preamble, the PHY header, and the MAC header.

The PPDU generation unit 1106 generates a PPDU using a PSDU, a PHY header, and a CRC code generated by the CRC code generation unit 1104. The PPDU generator 1106 performs modulation and coding on the data frame. The PPDU generator 1106 applies an MCS for which a data rate lower than that of the subframes is calculated for the preamble, the PHY header, and the MAC header. As a result, the probability that an error occurs in the preamble, the PHY header, and the MAC header is lower than that of the subframes.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium.

The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, a DVD, etc.) and a carrier wave (for example, the Internet). Storage medium).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a view showing the structure of a typical data frame used in the WPAN,

2 is a view showing a process of generating a data frame according to an embodiment of the present invention;

3 is a view showing the structure of a data frame according to an embodiment of the present invention;

4 is a diagram showing an MCS table according to an embodiment of the present invention;

5A and 5B illustrate the structure of a sub header and a sub frame according to the first embodiment of the present invention;

6A and 6B illustrate the structure of a sub header and a sub frame according to the second embodiment of the present invention;

7A and 7B illustrate structures of a sub header and a sub frame according to the third embodiment of the present invention;

8A and 8B illustrate structures of a sub header and a sub frame according to the fourth embodiment of the present invention;

9A and 9B illustrate structures of a sub header and a sub frame according to the fifth embodiment of the present invention;

10 is a view showing the structure of an ACK frame according to an embodiment of the present invention;

11 is a diagram illustrating an apparatus for generating a data frame according to an embodiment of the present invention.

Claims (23)

In the method for generating a data frame used in the WPAN, Generating a plurality of subframes using at least one MSDU; Generating a sub-header including information on the corresponding sub-frame for each of the sub-frames; And Generating a PSDU using the subframes and the subheaders and the MAC header, Each of the subframes has an FCS field for detecting an error of the corresponding subframe. The method of claim 1, The generating of the subframes may include a subframe including only first type bits and only second type bits using first type bits and second type bits extracted from the at least one MSDU. Generate a subframe including the subframe and all of the first type bits and the second type bits, The subheaders include a field indicating which bits the subframe consists of. The method of claim 1, A subframe including both first type bits and second type bits of the subframes may include separate fields in which FCSs for detecting errors are independently recorded for the first type bits and the second type bits. Method comprising a. The method of claim 1, The PSDU generation step, Generating a CRC code for detecting an error of the sub headers; And Combining the subframes, the subheaders and the CRC code with a MAC header. The method of claim 1, And the sub headers include a field indicating whether to request independent ACK for first type bits and second type bits of a corresponding subframe. The method of claim 1, And generating a PPDU for the PHY header, the subheaders, and the MAC header by applying an MCS for which a lower data rate is calculated than the subframes. The method of claim 1, The subheaders are fields in which an identifier of a corresponding MSDU is recorded when a subframe is one of fragments and a field in which information on the order of the subframes in the subdivisions of a corresponding MSDU is recorded. Method comprising a. The method of claim 1, Generating a PHY header comprising a field indicating whether the subframes are included in the data frame. The method of claim 1, Generating a CRC code for detecting errors in the preamble, the PHY header and the MAC header; And Generating a PPDU using the CRC code and the PSDU. The method of claim 1, The sub-headers include a field in which information on the MCS applied to the corresponding subframe is recorded. The method of claim 1, The sub-headers include a field in which information on the length of the corresponding sub-frame is recorded. In the apparatus for generating a data frame used in the WPAN, A subframe generation unit generating a plurality of subframes using at least one MSDU; A subheader generator configured to generate a subheader including information on a corresponding subframe for each of the subframes; And A PSDU generation unit generating a PSDU using the subframes and the subheaders and the MAC header, Each of the subframes has an FCS field for detecting an error of the corresponding subframe. The method of claim 12, The subframe generation unit may include: a subframe including only first type bits, a subframe including only second type bits, using first type bits and second type bits extracted from the at least one MSDU; Generate a subframe including both the first type bits and the second type bits, And the subheaders comprise a field indicating which bits the subframe consists of. The method of claim 12, A subframe including both first type bits and second type bits of the subframes may include separate fields in which an FCS for detecting an error is independently recorded for the first type bits and the second type bits. Apparatus comprising a. The method of claim 12, The PSDU generation unit, Generate a CRC code for detecting an error of the sub headers, and combine the sub frames, the sub headers, and the CRC code with a MAC header. The method of claim 12, And the sub headers include a field indicating whether to request an independent ACK for first type bits and second type bits of a corresponding subframe. The method of claim 12, The PHY header, the sub-headers and the MAC header further comprises a PPDU generation unit for generating a PPDU by applying the MCS is calculated that the lower data rate than the sub-frames. The method of claim 12, The sub-headers are fields in which an identifier of a corresponding MSDU is recorded and a field in which information about the order of the subframes within the corresponding MSDUs is recorded when the corresponding subframe is one of fragments of one MSDU. Apparatus comprising a. The method of claim 12, And a PHY header generator for generating a PHY header including a field indicating whether the sub-headers are included in the data frame. The method of claim 12, A CRC code generator for generating a CRC code for detecting an error of the preamble, the PHY header, and the MAC header; And The apparatus further comprises a PPDU generation unit for generating a PPDU using the CRC code and the PSDU. The method of claim 12, And the sub headers include a field in which information on an MCS applied to a corresponding sub frame is recorded. The method of claim 12, The sub-headers include a field in which information on the length of the corresponding sub-frame is recorded. A recording medium having recorded thereon a computer program for executing the method according to any one of claims 1 to 11.

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