Patent Application
20180191453
The present invention relates to technology of a wireless communication system.
Priority is claimed on Japanese Patent Application No. 2015-137687, filed Jul. 9, 2015, the content of which is incorporated herein by reference.
Advances in technology in which a user terminal typified by a mobile phone terminal performs data communication during movement (technology of mobile wireless data communication) are remarkable and technological innovation of various wireless communication schemes has been made and put to practical use. In recent years, communication standards accelerating fourth generation data communication such as a Long Term Evolution (LIE) scheme or a Worldwide Interoperability for Microwave Access (WiMAX) scheme using orthogonal frequency division multiple access (OFDMA) technology have become mainstream. In OFDMA, access of a plurality of terminal devices is enabled by orthogonal frequency division multiplexing (OFDM).
On the other hand, a communication scheme of a wireless local area network (LAN) in which a personal computer (PC) or the like is mainly mounted has been developed on the basis of a communication procedure with a base station device using a carrier sense multiple access with collision avoidance (CSMA/CA) scheme. The IEEE 802.11 working group who is establishing the standard of the communication scheme of the wireless LAN has begun to consider the application of technology of OFDMA to a wireless LAN communication scheme based or the current CSMA/CA to more efficiently implement data communication.
In the conventional technology of Patent Literature 1, with respect to a transmission method prescribed in the IEEE 802.11ac wireless LAN communication standard, a preamble of a frame includes a first signal field (VHT-SIG-A) and a second signal field (VHT-SIG-B). Also, in a multiuser (MU) mode, simultaneous data communication destined for a plurality of devices is implemented by performing space division multiplexing using a dedicated space-time stream for each of a plurality of destination devices.
[Patent Literature 1]
Japanese Patent No. 5607249
However, m the conventional technology of Patent Literature 1, it is possible to include only data destined for aw device per space-time stream. Thus, it is possible to perform multiplexed transmission only for a maximum number of devices capable of simultaneously using a space-time stream (four devices at maximum in the IEEE 802.11ac scheme).
Generally, in a wireless LAN, a collision probability of a radio frame is reduced by inspecting an unused state of a radio channel before a radio frame is transmitted and additionally providing a random waiting time to shift a transmission timing. The radio channel inspection procedure and the transmission waning procedure performed prior to the transmission of the radio frame become overheads that degrade the performance of communication. Particularly, because an influence of the overheads increases when the number of devices using the same radio channel increases, it is desirable to improve the communication efficiency by reducing the overheads.
The present invention has been made in view of such circumstances, and an objective of the present invention is to provide a transmitting device, a receiving device, a wireless communication system, a wireless communication method, and a computer program capable of improving the utilization efficiency of a radio frame.
(1) An aspect of the present invention is a transmitting device including: a data transmitting unit configured to wirelessly transmit a frame including a payload part in which data destined tor a plurality of receiving devices is frequency-division multiplexed and a header including a signal field part storing division information about frequency division of the payload part.
(2) An aspect of the present invention is a transmitting device including: a data transmitting unit configured to wirelessly transmit a frame including a payload part in which data destined for a plurality of receiving devices is frequency-division multiplexed and a header including a first signal field part and a second signal field part subsequent to the first signal field part, wherein the second signal field part includes a plurality of division parts into which a frequency is divided in the same bandwidth as that of the payload part, and wherein the first signal field part stores division information about frequency division of the second signal field part and the payload part.
(3) In the transmitting device of the above-described (2), an aspect of the present invention is the transmitting device in which the payload part has data destined for a plurality of receiving de vices farther time-division multiplexed in a band corresponding to at least one division part of the second signal field part and the at least one division part of the second signal field part stores division information about time division of a payload part corresponding to the at least one division part.
(4) All aspect of the present invention is a transmitting device including: a data transmitting unit configured to wirelessly transmit a frame including a payload part in which data destined for a plurality of receiving devices is frequency-division multiplexed and a header including a first signal field part and a second signal field part subsequent to the first signal field part, wherein the second signal field part includes a plurality of division parts into which a frequency is divided, wherein the first signal field part stores division information about frequency di vision of the second signal field part, wherein the payload part has data destined for a plurality of receiving devices frequency-division multiplexed in a hand corresponding to at least one division part of the second signal field part, and wherein the at least one division part of the second signal field part stores division information about frequency division of a payload part corresponding to the at least one division part.
(5) An aspect of the present invention is a transmitting device including: a data transmitting unit configured to wirelessly transmit a frame including a payload part in which data destined for a plurality of receiving devices is frequency-division multiplexed and a header including a first signal field part and a second signal field part subsequent to the first signal field part, wherein the second signal field part includes a plurality of division parts into which a frequency is divided, wherein the first signal field part stores division information about frequency division of the second signal field part, wherein the payload part has data destined for a plurality of receiving devices multiplexed in a combination of frequency division multiplexing and time division multiplexing in a band corresponding to at least one division part of the second signal field part, and wherein the at least one division part of the second signal field part stores division information about frequency division and time division of a payload part corresponding to the at least one division part.
(6) In the transmitting device according to any one of the above-described (2) to (5), an aspect of the present invention is the transmitting device in which the data transmitting unit wirelessly transmits the first signal field part within the frame in all directions and wirelessly transmits a plurality of space-time streams including at least the second signal field part and the payload part in each direction and the first signal field part stores division information of the second signal field part tor each space-time stream.
(7) In the transmitting device according to any one of the above-described (2) to (6), an aspect of the present invention is the transmitting device in which the first signal field part includes a destination device identifier indicating a receiving device of a destination of data stored in a division part for each division part of the payload part.
(8) An aspect of the present invention is a receiving device including: a data receiving unit configured to receive the frame wirelessly transmitted from the transmitting device according to any one of the above-described (1) to (6); a header analyzing unit configured to analyze the header of the frame received by the data receiving unit; and a payload demapping unit configured to acquire data from the payload part of the frame received by the data receiving unit on the basis of a result of analyzing the header in the header analyzing unit.
(9) An aspect of the present invention is a receiving device including: a data receiving unit configured to receive the frame wirelessly transmitted from the transmitting device according to the above-described (7); a header analyzing unit configured to analyze the header of the frame received by the data receiving unit; and a payload demapping unit configured to acquire data from only a division part including data destined tor the receiving device among division parts of the payload part of the frame received by the data receiving unit on the basis of a result of analyzing the header in the header analyzing unit.
(10) An aspect of the present invention is a wireless communication system including: a base station device including the transmitting device according to any one of the above-described (1) to (6); and a terminal device including the receiving device according to the above-described (8).
(11) An aspect of the present invention is a wireless communication system including: a base station device including the transmitting device according to the above-described (7); and a terminal device including the receiving device according to the above-described (9).
(12) An aspect of the present invention is a wireless communication method including a step of: wirelessly transmitting, by a transmitting device, a frame including a payload part in which data destined for a plurality of receiving devices is frequency-division multiplexed and a header including a signal field part storing division information about frequency division of the payload part.
(13) An aspect of the present invention is a computer program for causing a computer of a transmitting device to execute a step of: wirelessly transmitting a frame including a payload part in which data destined for a plurality of receiving devices is frequency-division multiplexed and a header including a signal field part storing division information about frequency division of the payload part.
According to the present invention, it is possible to improve utilization efficiency of a radio frame.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The transmitting device 100 shown, in
The user subcarrier mapping unit 102 allocates subcarriers and the like in the payload part of the radio frame with respect to each receiving device 200. The user subcarrier mapping unit 102 makes a plan of mapping of data to be stored in the payload part in consideration of a modulation method when a plurality of transmission data packets having the MAC frame format within the buffer memory 101 are transmitted to each receiving device 200.
The payload mapping unit 103 receives a transmission data packet from the buffer memory 101. The payload mapping unit 103 modulates the transmission data packet received from the buffer memory 101 in accordance with the mapping plan by the user subcarrier mapping unit 102 and maps modulated data to frequency resources and time resources of the payload part.
The header generating unit 104 generates a header of the radio frame on the basis of the mapping plan by the user subcarrier mapping unit 102. The data transmitting unit 105 generates a radio frame by using the header generated by the header generating unit 104 and the payload part generated by the payload mapping unit 103, converts the generated radio frame into a signal in a radio frequency band, and wirelessly transmits the signal. The radio frame wirelessly transmitted from the transmitting device 100 is received by the receiving device 200.
The receiving device 200 shown in
The header analyzing unit 202 performs header analysis on the radio frame converted into the signal of the baseband frequency by the data receiving unit 201. The header analyzing unit 202 outputs a header analysis result to the payload demapping unit 203.
The payload demapping unit 203 performs demapping and demodulation of the payload part of the radio frame converted into the baseband frequency signal by the data receiving unit 201 on the basis of the header analysis result from the header analyzing unit 202. The data selecting unit 204 selects only a MAC frame destined for its own receiving device 200 from a result of demapping and demodulating the payload part in the payload demapping unit 203 and discards MAC frames other than the MAC frame destined for its own receiving device 200.
The buffer memory 205 temporarily stores the MAC frame destined for its own receiving device 200 selected by the data selecting unit 204. The MAC frame stored in the buffer memory 205 is output from the buffer memory 205 in a data format of the received data packet. The received data packet may be output to another functional unit within the terminal device 20 equipped with the receiving device 200 or may be output to a device other than the terminal device 20 provided with the receiving device 200.
Also, the transmission data packet and the received data packet are, for example, Internet protocol (IP) packets.
Next, an example of a configuration of a radio frame according to the present embodiment will be described.
The radio frame shown in
The second signal field part and the payload part are frequency-divided with the same bandwidth. In the present embodiment, the OFDM scheme is used for frequency division multiplexing of data in the second signal field part and the payload part. For example, if the entire radio frame has a bandwidth of 80 MHz, 80 MHz of the entire band of the radio frame is divided into four small bands each having 20 MHz. In this case, the number of divisions is “N=4,” and the second signal field part is frequency-divided into four division parts HE-SIG-B-1, 2, 3, and 4. Also, the payload part is frequency-divided into four division parts of a “data part of destination 1,” a “data part of destination 2,” a “data, part of destination 3,” and a “data part of destination 4” corresponding to four division parts HE-SIG-B-1, 2, 3, and 4 of the second signal field part. Data destined for a plurality of receiving devices 200 is stored in each small band which is a division part of a payload part.
Each division part of the second signal field part stores information such as a modulation method of the division part of the corresponding payload part. For example, if the above-described number of divisions is “N=4,” the division part HE-SIG-B-1 in the second signal field part stores information such as the modulation method of the division part “data part of destination 1” of the payload part, the division part HE-SIG-B-2 stores information such as the modulation method of the division part “data part of destination 2” of the payload part, the division part HE-SIG-B-3 stores information such as the modulation method of the division part “data part of destination 3” of the payload part, and the division part HE-SIG-B-4 stores information such as the modulation method of the division part “data part of destination 4” of the payload part.
Also, the second signal field part may store a data length of data to be transmitted to each receiving device 200.
The first signal field part stores bandwidth information indicating a bandwidth of the entire radio frame shown in
Also, if the second signal field part is divided in a fixed form, an identifier indicating each division part of the fixed form may be predetermined and the identifier may be used as the division range information. For example, if the entire bandwidth of the radio frame is divided in units of 20 MHz, a number indicating an order corresponding to each division part such as a first 20 MHz division part, a second 20 MHz division part, and a third 20 MHz division part may be designated as the division range information.
Also, the arrangement of the first signal field part is not limited to the configuration example of
In
In the payload part of each of the small bands f1, f2, f3, and f4, modulated data in which data destined for each receiving device 200 is modulated in the modulation method indicated by the second signal field part is stored. The method of storing the modulated data in the payload part is defined in the wireless communication scheme used in the wireless LAN system 1. The direction of reading data within the payload past indicated by the arrows in
The header generating unit 104 of the transmitting device 100 generates a legacy preamble part, a first signal field part, an HE-STF part, an HE-LTF part, and a second signal field part to be included in the header of the radio frame. The header analyzing unit 202 of the receiving device 200 analyzes the legacy preamble part, the first signal field part, the HE-STF part, the HE-LTF part and the second signal field part included in the header of the radio frame.
The above is the description of the configuration example 1 of the radio frame.
Here, a modified, example of the configuration example 1 of the above-described radio frame will be described. In the configuration example 1 of the above-described radio frame, the first signal field part stores bandwidth information indicating a bandwidth of the entire radio frame and division information about frequency division of the second signal field part. The division information includes number-of-divisions information indicating the number of divisions N of the second signal field part and division range information indicating a frequency band of each division part of the second signal field part. In the present modified example, a destination device identifier indicating a destination device of data to be stored in die division part is further included for each division part of the pay load part with respect to the division information. The destination device identifier may be included in combination with the division range information. Thereby, the processing load of the receiving device 200 can be reduced. This point will be described below.
A conventional wireless LAN receiving device identifies a receiver address included in a MAC frame obtained by demodulating a payload part included in a radio frame to determine whether or not the radio frame is destined for its own device. According to this conventional radio frame determination method, in the case of the above-described radio frame shown in
On the other hand, according to the present modified example, by further including the destination device identifier in the division information stored in the first signal field part, the header analyzing unit 202 of the receiving device 200 can determine whether or not the radio frame includes data destined for its own receiving device 200 and further determine a payload part of a small band of the radio frame including data destined for its own receiving device 200 from a result of analyzing the first signal field part of the radio frame. Thereby, it is possible to reduce a processing load of the receiving device 200 because it is only necessary for the payload demapping unit 203 of the receiving device 200 to demodulate only a payload part of a small band including data destined for its own receiving device 200 among small bands of the radio frame.
Also, a MAC address of the receiving device 200 or a connection number (an association ID) of the wireless LAN system 1 may be used as the destination device identifier stored in the first signal field part. However, from a viewpoint of security, it is preferable to set a value obtained by converting the MAC address or the connection number according to an information compression process or the like or combining the MAC address or the connection number with other information as a destination device identifier instead of using the MAC address of the receiving device 200 or the connection number of the wireless LAN system 1 as a destination device identifier as it is. This is because the header is not generally encrypted and it is not preferable to store the MAC address or the connection number which is one piece of detailed information of the receiving device 200 in an unencrypted header as it is from the viewpoint of security.
Thus, for example, a value obtained by shortening the MAC address or the connection number may be designated as the destination device identifier. For example, a predetermined number of less significant bits of the MAC address or the connection number may be designated as the destination device identifier. Alternatively, the destination device identifier may be a combination of a multiaccess (MA) group identifier indicating a group to which the receiving device 200 belongs with respect to multiaccess of the wireless LAN system 1 and the value obtained by shortening the MAC address or the connection number. In this manner, preferably, it is impossible to uniquely identify the receiving device 200 only by analyzing the header of the radio frame.
Also, as the MA group identifier, an identifier of a group of the receiving device 200 of the destination of the data to be multiplexed by OFDMA may be used. Also, for example, a plurality of receiving devices 200 for which it is preferable to perform multiplexing by OFDMA may be grouped into the same identifier group.
In the example of
According to the example of
Also, in the configuration example 2 of the radio frame shown in
The header generating unit 104 of the transmitting device 100 generates a legacy preamble part, a first signal field part, an HE-STF part, an HE-LTF part, and a second signal field part to be included in the header of the radio frame. The header analyzing unit 202 of the receiving device 200 analyzes the legacy preamble part, the first signal field part, the HE-STF part, the HE-LTF part and the second signal field part included in the header of the radio frame.
The above is the description of the configuration example 2 of the radio frame.
In the example of
According to the example of
Also, in the configuration example 3 of the radio frame shown in
The header generating unit 104 of the transmitting device 100 generates a legacy preamble part, a first signal field part, an HE-STF part, an HE-LTF part, and a second signal field part to be included in the header of the radio frame. The header analyzing unit 202 of the receiving device 200 analyses the legacy preamble part, the first signal field part, the HE-STF part, the HE-LTF part and the second signal field part included in the header of the radio frame.
The above is the description of the configuration example 3 of the radio frame.
In the example of
Also, in the configuration example 4 of the radio frame shown in
The header generating unit 104 of the transmitting device 100 generates a legacy preamble part, a first signal field part, an. HE-STF part, an HE-LTF part, and a second signal field part to be included in the header of the radio frame. The header analyzing unit 202 of the receiving device 200 analyzes the legacy preamble part, the first signal field part, the HE-STF part, the HE-LTF part and the second signal field part included in the header of the radio frame.
The above is the description of the configuration example 4 of the radio frame.
Also, in one radio frame, any one of the above-described configuration examples 1 to 4 of the radio frame may be used alone, or any two or more thereof may be combined. For example, the payload part may be configured differently in each of the small bands f1, f2, f3, and f4 shown in
In the example of
The data receiving unit 201 of the transmitting device 100 wirelessly transmits the legacy preamble part (the legacy preamble) and the first signal field part (HE-SIG-A) within the radio frame shown in
The above is the description of the configuration example 5 of the radio frame. In the above-described example of
Also, in actual wireless communication in the wireless LAN system 1, signals defined in the wireless LAN system 1 such as a guard interval and a pilot signal are further added to the radio frame with respect to the above-described configuration examples 1 to 5 of the radio frame.
According to the above-described embodiment, because data destined for a plurality of receiving devices 200 can be stored in one radio frame, the utilization efficiency of the radio frame can be improved. Thereby, the effect of reducing the influence of the deterioration of the communication performance due to overheads of the radio channel inspection procedure or the transmission waiting procedure performed before the transmission of the radio frame can be obtained. The effects of the present embodiment will be described below with specific examples. In the following description of the specific example, an example using a transmission method defined in the IEEE 802.11ac wireless LAN communication standard will be described.
Although embodiments of the present invention have been described above with reference to the drawings, specific configurations arc not limited to the embodiments, and a design change, etc. may also be included without departing from the scope of the present invention.
For example, the present invention is applied to a wireless LAN system in the above-described embodiment, but may be applied to a wireless communication system other than the wireless LAN system.
Also, a computer program for implementing functions of the above-described transmitting device 100 or receiving device 200 may be recorded on a computer-readable recording medium and a computer system may read and execute the program recorded on the recording medium. Also, the “computer system” used here may include an operating system (OS) and hardware such as peripheral devices.
Also, the “computer-readable recording medium” refers to a non-transitory storage device including a rewritable nonvolatile memory such as a flexible disk, a magneto-optical disc, a read only memory (ROM), or a flash memory, a portable medium such as a digital versatile disk (DVD), and a hard disk embedded in the computer system.
Furthermore, the “computer-readable recording medium” is assumed to include a medium that holds a program for a constant period of time, such as a volatile memory (for example, a dynamic random access memory (DRAM)) inside a computer system serving as a server or a client when the program is transmitted via a network such as the Internet or a communication circuit such as a telephone circuit.
Also, the above-described program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by transmission waves in a transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) like the Internet or a communication circuit (communication line) like a telephone circuit.
Also, the above-described program may be a program for implementing some of the above-described functions. Further, the above-described program may be a program capable of implementing the above-described function in combination with a program already recorded on the computer system, i.e., a so-called differential file (differential program).
The present invention can be applied to a field of application in which it is necessary to improve utilization efficiency of a radio frame.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-137687 | Jul 2015 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2016/068685 | 6/23/2016 | WO | 00 |
