KR20120025378A - System and method for measuring round trip time based on wireless local area network - Google Patents

System and method for measuring round trip time based on wireless local area network Download PDF

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KR20120025378A
KR20120025378A KR1020110061089A KR20110061089A KR20120025378A KR 20120025378 A KR20120025378 A KR 20120025378A KR 1020110061089 A KR1020110061089 A KR 1020110061089A KR 20110061089 A KR20110061089 A KR 20110061089A KR 20120025378 A KR20120025378 A KR 20120025378A
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South Korea
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signal
time
transmission
rtt
reception
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KR1020110061089A
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Korean (ko)
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김동규
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한국전자통신연구원
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Priority to US13/226,858 priority Critical patent/US20120057481A1/en
Publication of KR20120025378A publication Critical patent/KR20120025378A/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/28—Flow control; Congestion control in relation to timing considerations
    • H04L47/283—Flow control; Congestion control in relation to timing considerations in response to processing delays, e.g. caused by jitter or round trip time [RTT]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/01—Protocols
    • H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
    • H04L67/125—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks involving control of end-device applications over a network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H04W64/003—Locating users or terminals or network equipment for network management purposes, e.g. mobility management locating network equipment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • Computing Systems (AREA)
  • General Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

PURPOSE: A system for measuring RTT(Round Trip Time) of WLAN(Wireless Local Access Network) and a method thereof are provided to measure more accurate RTT in a physical layer than in a network layer and a link layer. CONSTITUTION: A first and a second signal time measuring units(300,400) are respectively connected to two WLAN devices(100,200) for WLAN communication. The first and the second signal time measuring units measure the signal time difference between transmitting signals and receiving signals corresponding to the transmitting signal of the each WLAN device. A RTT estimating unit(500) estimates RTT by a measured signal time difference.

Description

Wireless LAN-based round trip time measurement system and method {SYSTEM AND METHOD FOR MEASURING ROUND TRIP TIME BASED ON WIRELESS LOCAL AREA NETWORK}

The present invention relates to a wireless local area network (WLAN) based round trip time measurement apparatus and method, and more particularly, to a round trip time measurement technique used for WLAN based positioning.

The positioning method using a wireless local area network (WLAN) is typically a method using Received Signal Strength (RSS), a method using an Angle of Arrival (AoA) and a signal round trip. There is a method using a round trip time (RTT).

The positioning method using RSS has various methods such as a method of estimating a location by measuring a signal transmission distance due to signal attenuation by measuring the strength of a received signal, a method of simply using a signal attenuation value, or a pattern of a signal attenuation value. It is proposed. The positioning method using the RSS has an advantage that it is easy to implement the software in the WLAN device, but the position estimation accuracy and the performance is estimated to be lower than the method using the AoA or RTT.

The positioning method using AoA is a method of estimating the position at which the signal is transmitted by analyzing the propagation path of the signal by measuring the incident angle of the signal received from the antenna having the position. As the spread of WLAN devices based on Multiple Input Multiple Output (MIMO) has been expanded, the possibility of implementation of a positioning method using AoA has been proposed, but since the technology needs to be installed in the hardware of WLAN devices, the feasibility is evaluated to be low. have. In addition, this method has a disadvantage in that the precision is significantly lowered in a multipath severe environment.

Positioning method using the RTT is the most widely used for positioning, such as GPS, IEEE802.15.4a, and transmits and receives signals between two WLAN devices to measure the distance between the two WLAN devices by measuring the RTT between the two WLAN devices From this, the position of the counterpart WLAN device is measured. The distance between two WLAN devices can be obtained as the product of the RTT and the propagation speed.

In the case of the positioning method using the RTT, the RTT measurement methods in the application layer, the network layer, and the link layer have been proposed since very precise position measurement is possible in an environment where positioning line of sight is secured. The RTT method that can be easily applied to WLAN devices is an RTT method at the application layer and the network layer, but it is difficult to accurately measure the RTT because random delay time occurs during data transmission between the medium access control layer and the physical layer. . The link layer RTT method, which has more precise measurement performance than the RTT method at the application layer and the network layer, cannot be applied to an existing WLAN device and has to change hardware of the existing WLAN device.

The present invention has been made in an effort to provide a wireless LAN-based round trip time measurement system and method capable of measuring precise RTT without changing hardware of an existing WLAN device.

According to an embodiment of the present invention, a system for measuring a round trip time (RTT) based on a wireless local area network (WLAN) is provided. The RTT measurement system includes first and second signal time meters and an RTT estimator. The first and second signal time meters are respectively connected to two WLAN devices performing WLAN communication, and measure the difference in signal time between a transmission signal from each WLAN device and a received signal of each WLAN device corresponding to the transmission signal. Measure The RTT estimator estimates the RTT using the signal time difference measured from the first and second time meters, respectively.

Each of the first and second signal time measuring instruments may include: a reception time detection unit detecting a transmission time of the transmission signal and a reception time of the reception signal, a signal detection unit determining the type of the transmission signal and the reception signal, and the transmission And a time calculator configured to calculate a signal time difference necessary for estimating the RTT by using a transmission time of the transmission signal and a reception time of the reception signal according to a signal and a type of the reception signal.

Each of the first and second signal time measuring instruments may further include an antenna configured to detect and transmit a transmission signal of a corresponding WLAN device and a reception signal of the corresponding WLAN device to the reception time detector.

The signal detector may determine the type of the transmission signal and the reception signal by demodulating and decoding the transmission signal and the reception signal.

One of the transmitted signal and the received signal includes a probe request or a probe response, and when the received signal is a probe request, the transmitted signal includes a probe response and the received signal is In the case of a probe response, the transmission signal may include a probe request and an acknowledgment for the probe response.

One of the transmission signal and the received signal includes a request to send or a clear to send, and when the received signal is the transmission request, the transmission signal includes the transmission confirmation, When the received signal confirms the transmission, the transmission signal may include a transmission request.

One of the transmitted signal and the received signal includes a command request or a command response, and when the received signal is the command request, the transmitted signal includes the command response and the received If the signal is the command response, the transmission signal may include a command request.

One of the transmitted signal and the received signal includes data or acknowledgment, and when the received signal is the data, the transmitted signal includes the acknowledgment and the received signal is the acknowledgment. The transmission signal may include data.

According to another embodiment of the present invention, a method for measuring an RTT using a signal transmitted and received between two wireless local area network (WLAN) devices in a round trip time (RTT) measurement system is provided. The RTT measuring method may include receiving a transmission signal of a WLAN device connected to itself and a reception signal corresponding to the transmission signal at first and second signal time meters respectively connected to two WLAN devices. Measuring a signal time difference between the transmission signal and the received signal in a second signal time meter, and estimating the RTT using the signal time difference measured by the first and second signal time meters in the RTT estimator, respectively. It includes.

The measuring may include receiving a transmission signal and a reception signal of a WLAN device connected to the self, detecting a reception time of the transmission signal and the reception signal, and a reception time and the transmission of the reception signal. Computing the signal time difference using the transmission time of the signal.

According to an embodiment of the present invention, since the RTT can be measured at the physical layer of the existing WLAN device without changing the hardware of the existing WLAN device, the RTT can be measured more accurately at the application layer, the network layer, and the link layer.

1 is a diagram illustrating a WLAN-based round trip time measurement system according to an exemplary embodiment of the present invention.
2 to 4 are diagrams illustrating a modified example of the WLAN-based round trip time measurement system.
5 to 7 are diagrams illustrating an RTT estimation method performed in the WLAN-based round trip time measurement system of FIGS. 2 to 4, respectively.
8 to 11 are diagrams illustrating a signal time difference between a signal used in a WLAN device and a corresponding signal.
12 is a diagram illustrating a signal time meter according to an exemplary embodiment of the present invention.
13 is a flowchart illustrating a method of measuring a signal time value in a signal time meter according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification and claims, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Now, a WLAN and a round trip time measurement system and method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a wireless LAN-based round trip time measurement system according to an embodiment of the present invention, Figures 2 to 4 are views showing a modified example of the wireless LAN-based round trip time measurement system.

Referring to FIG. 1, a WLAN-based round trip time measurement system 10 includes two wireless local area network (WLAN) devices 100 and 200, a signal time meter 300 and 400, and a round trip time. RTT) estimator 500.

The WLAN devices 100 and 200 refer to a device equipped with a WLAN wireless communication module. For example, the WLAN devices 100 and 200 may be user terminals such as a smartphone or a notebook computer equipped with a wireless access device (AP) or a WLAN wireless communication module. Can be.

These WLAN devices 100 and 200 may transmit and receive signals in WLAN wireless communication using the WLAN wireless communication module.

The signal time meters 300 and 400 are directly connected to the WLAN devices 100 and 200 in a wired or wireless manner, respectively. For example, the signal time meters 300 and 400 may be connected to the WLAN devices 100 and 200 through USB or serial connection, respectively.

The signal time detectors 300 and 400 detect a transmission time of a transmission signal and a reception time of a reception signal corresponding to the transmission signal in the physical layers of the two WLAN devices 100 and 200.

The signal time measuring units 300 and 400 respectively calculate a signal time difference between the transmission time point of the transmission signal and the reception time point of the reception signal, and transmit the calculated signal time difference to the RTT estimator 500.

The RTT estimator 500 estimates the RTT between the two WLAN devices 100 and 200 by using the signal time difference received from the signal time meters 300 and 400.

The distance between the two WLAN devices 100 and 200 may be calculated by multiplying the estimated RTT by the propagation speed, and the position of the counterpart WLAN device may be estimated from the calculated distance between the two WLAN devices 100 and 200.

The RTT estimator 500 may be implemented in software or hardware logic or a combination thereof depending on the purpose of implementation.

In addition, the RTT estimator 500 may be a separate device from the WLAN devices 100 and 200 and the signal time meters 300 and 400, as shown in FIG. May be implemented in one of (300, 400).

For example, as shown in FIG. 2, the RTT estimator 500 may be implemented as one device 30 together with the signal time meter 300, and as shown in FIG. 3, the WLAN device 100. , 200 may be implemented as one device 20 together with one of them. Alternatively, the RTT estimator 500 may be implemented in the external device 40 as shown in FIG. 4. In this case, the RTT estimator 500 implemented in the external device 40 may be connected to the signal time meter 400 and the WLAN device 200 through the network 1, and the signal time meter 300 may be the WLAN device 100. ) May be directly connected. In this case, the signal time difference information measured by the signal time measurer 300 may be transmitted to the RTT estimator 500 through the WLAN devices 100 and 200. The network 1 may be a public network such as a wide area network (WAN), a local network such as a local area network (LAN), or the like. Alternatively, the signal time meters 300 and 400 may be connected via the network 1.

Next, an RTT estimating method according to an embodiment of the present invention will be described in detail with reference to FIGS. 5 to 7.

5 to 7 are diagrams illustrating an RTT estimation method performed in the WLAN-based round trip time measurement system of FIGS. 2 to 4, respectively.

First, FIG. 5 is an RTT estimating method when the RTT estimator 500 is implemented as a single device together with the signal time measurer 300 as shown in FIG. 2. In FIG. 5, a device in which the RTT estimator 500 and the signal time measurer 300 are implemented is illustrated as a signal time measurer 300.

Referring to FIG. 5, two WLAN apparatuses 100 and 200 establish a WLAN wireless connection to transmit and receive a signal (S510), and transmit and receive a signal through WLAN wireless communication (S520). The signal time measuring devices 300 and 400 are signals between the transmission signal and the reception signal necessary for the RTT estimation from the transmission time of the transmission signal in the physical layer of the WLAN device 100 and 200 and the reception time of the reception signal corresponding to the transmission signal. Time difference is measured (S530, S540).

For example, when the WLAN device 100 transmits a signal and the WLAN device 200 transmits a response signal to the WLAN device 100 after receiving the signal at the WLAN device 200, the signal time meter ( 300 receives a signal transmitted by the WLAN device 100 and measures a transmission time point at which the WLAN device 100 transmits a signal. In addition, the signal time measuring unit 400 receives a signal transmitted from the WLAN device 100 in the same manner as the WLAN device 200 and measures a reception time of the signal. In addition, the signal time measuring unit 300 receives the response signal transmitted from the WLAN device 200 in the same manner as the WLAN device 100 and measures the reception time of the response signal. Thereafter, the signal time measuring unit 300 measures the signal time difference between the transmission time of the signal and the reception time of the response signal. The signal time measurer 400 may also measure the signal time difference in the same manner as the signal time measurer 300.

The signal time measurer 400 transmits the measurement information, that is, the signal time difference to the WLAN device 200 (S550), and the WLAN device 200 sends the signal time measurer 400 to the WLAN device 100 that is reconnected. The measurement information is transmitted (S560). The WLAN device 100 transmits the received measurement information to the signal time measurer 300 in which the RTT estimator 500 is implemented (S570).

The signal time measurer 300 estimates the RTT of the corresponding signal using the measurement information of the signal time measurer 400 and the measurement information measured by the signal time measurer 400 (S580).

When the RTT estimation is to be terminated, the two WLAN devices 100 and 200 may release the WLAN wireless connection setting.

FIG. 6 is an RTT estimating method when the RTT estimator 500 is implemented as one device together with the WLAN device 400 as shown in FIG. 3.

In FIG. 6, for convenience of description, a device in which the RTT estimator 500 and the WLAN device 400 are implemented is illustrated as a WLAN device 400.

Referring to FIG. 6, when the signal time difference required for the RTT estimation is measured in the signal time measuring units 300 and 400 in the same manner as in FIG. 5 (S610 ˜ S640), the signal time measuring unit 300 is the WLAN device 100. The measurement information is transmitted to the WLAN device 200 in which the RTT estimator 500 is implemented (S650 and S670), and the signal time measurer 400 transmits the measurement information to the WLAN device 200 (S660).

Then, the WLAN device 200 estimates the RTT using the time measurement information of the signal time meters 300 and 400 (S680).

FIG. 7 illustrates an RTT estimating method when the RTT estimator 500 is implemented in an external device as shown in FIG. 6.

Referring to FIG. 7, when the signal time difference required for the RTT estimation is measured in the signal time measuring units 300 and 400 in the same manner as in FIG. 5 (S710 to S740), the signal time measuring unit 400 determines the network 1. The measurement information is transmitted to the RTT estimator 500 through step S760.

In addition, the signal time measuring unit 300 transmits the measurement information to the WLAN device 100 connected thereto (S760), and the WLAN device 100 again transmits the measurement information of the signal time measuring unit 300 to the WLAN device 200. In step (S770). Then, the WLAN device 200 transmits the measurement information of the signal time measurer 300 to the RTT estimator 500 through the network 1 (S780).

The RTT estimator 500 estimates the RTT using the measurement information of the received signal time meters 300 and 400 (S790).

Next, a signal time difference used for RTT estimation according to a signal generally used in the WLAN apparatuses 100 and 200 and a type of the signal will be described in detail with reference to FIGS. 8 to 11.

8 to 11 are diagrams illustrating a signal time difference between a signal used in a WLAN device and a corresponding signal.

Referring to FIG. 8, the WLAN device 100 may transmit a probe request to the WLAN device 200 (S810).

The WLAN device 200 that receives the probe request transmits a probe response to the WLAN device 100 (S820), and the WLAN device 100 that receives the probe response receives the probe response. The acknowledgment is transmitted to the device 200 (S830).

In this case, the signal time measurer 300 receives a probe request transmitted by the WLAN device 100 at the physical layer, measures a transmission time a of the probe request, and measures a probe response ( The probe response is received in the same manner as the WLAN device 100 to measure the reception time c of the probe response. In addition, the signal time measuring unit 300 receives an acknowledgment transmitted by the WLAN device 100 and measures a transmission time e of the acknowledgment.

The signal time measuring unit 400 receives a probe request transmitted by the WLAN device 100 in the same manner as the WLAN device 200, and measures a reception time b of the probe request, and then measures the WLAN device. The probe 200 transmits a probe response and detects a transmission time d of the probe response. In addition, the signal time measuring unit 400 receives an acknowledgment transmitted by the WLAN device 100 in the same manner as the WLAN device 200 and measures a reception time f of the acknowledgment.

The signal time measuring unit 300 measures a signal time difference t1 between a transmission time a of a probe request and a reception time d of a received probe response, and then probe response. The signal time difference t2 between the reception time d of the e) and the transmission time e of the acknowledgment is measured. In addition, the signal time measuring unit 400 measures a signal time difference t3 between the reception time b of the probe request and the transmission time d of the probe response in the physical layer, and the probe response The signal time difference t4 between the transmission time d of the probe response and the reception time f of the acknowledgment is measured.

Thereafter, the signal time measurer 300 transmits the measured signal time differences t1 and t2 to the RTT estimator 500, and the signal time measurer 400 transmits the measured signal time differences t3 and t4 to the RTT estimator. Forward to 500.

Next, referring to FIG. 9, when there is data to be transmitted, the WLAN device 100 may transmit a request to send (RTS) to the WLAN device 200 for resource reservation (S910). After receiving the RTS, the WLAN device 200 transmits a transmission confirmation (Clear To Send, CTS) to the WLAN device 100 (S920).

In this case, the signal time measuring device 300 measures the transmission time g of the RTS and the reception time i of the CTS in the physical layer in the same manner as described in FIG. The signal time difference t5 of the reception time i of the CTS is measured and transmitted to the RTT estimator 500. In addition, the signal time measuring unit 400 also measures the reception time h of the RTS and the transmission time j of the CTS in the physical layer in the same manner as described in FIG. 8, and the reception time h of the RTS and the CTS of the CTS. The signal time difference t6 of the transmission time j is measured and transmitted to the RTT estimator 500.

In addition, referring to FIG. 10, the WLAN device 100 may transmit a command request to the WLAN device 200 (S1010). In response to the command request, the WLAN device 200 transmits a command response to the WLAN device 100 in response (S1020).

In this case, the signal time measurer 300 measures the transmission time k of the command request and the reception time m of the command response in the physical layer, and measures the time of the command request. The signal time difference t7 between the transmission time k and the reception time m of the command response is measured and transmitted to the RTT estimator 500. In addition, the signal time measuring unit 400 measures the reception time l of the command request and the transmission time n of the command response in the physical layer, and the reception time of the command request. The signal time difference t8 between (l) and the transmission time n of the command response is measured and transmitted to the RTT estimator 500.

Next, referring to FIG. 11, when a resource reservation for transmitting data is completed, the WLAN device 100 may transmit data to the WLAN device 200 (S1110). In operation S1120, the WLAN device 200 having received the data transmits an acknowledgment of the data to the WLAN device 100.

In this case, the signal time measuring device 300 measures the transmission time o of the data and the reception time q of the acknowledgment in the physical layer, and the transmission time o of the data. The signal time difference t9 of the reception time q of the acknowledgment is measured and transmitted to the RTT estimator 500. In addition, the signal time measuring unit 400 measures the reception time (p) of the data (Data) and the transmission time (r) of the acknowledgment (Acknowledgement) at the physical layer, and receives the reception time (p) and reception of the data (Data). The signal time difference t10 of the transmission time r of acknowledgment is measured and transmitted to the RTT estimator 500.

12 is a diagram illustrating a signal time meter according to an exemplary embodiment of the present invention.

Although FIG. 12 illustrates the signal time meter 300 of FIG. 1, the signal time meter 400 may also be configured similarly to the signal time meter 300.

Referring to FIG. 12, the signal time measuring unit 300 includes an interface unit 310, an antenna 320, a reception time detector 330, a signal detector 340, a time calculator 350, and a controller 360. do.

The interface unit 310 connects to the WLAN device 100 or the communication network 10.

The antenna 320 detects and transmits a signal transmitted through the physical layer of the WLAN device 100 or a received signal to the reception time detector 330.

The reception time detector 330 detects a reception time of a signal received and sensed through the antenna 320, that is, a baseband reception signal, and transmits the detected reception time to the signal detector 340 and the time calculator 350. do.

Here, the reception time point of the received signal refers to the transmission time point of the signal transmitted from the WLAN device 100 when the signal transmitted from the WLAN device 100 is received. In addition, the reception time of the received signal may be the reception time of the signal received by the WLAN device 100 when the signal received by the WLAN device 100 is received in the same manner as the WLAN device 100.

That is, the reception time detected by the reception time detection unit 330 may be a transmission time of a probe request illustrated in FIG. 8, or may be a reception time of a probe response illustrated in FIG. 8. have.

The signal detector 340 determines the type of the corresponding signal from the baseband received signal, and transmits the determination result to the time calculator 350. That is, the signal detector 340 is whether the baseband received signal is a probe request, a probe response, a probe response, an RTS, a CTS, or a command request, or a command response. Or acknowledgment.

The time calculator 350 calculates a signal time difference according to the type of the received signal by using the reception time of the reception signal and the reception time of the signal corresponding to the reception signal.

For example, when the signal is a probe response, the time calculator 350 transmits a probe request corresponding to a reception time of a probe response and a probe response. Signal time differences t1 and t2 shown in FIG. 8 may be calculated using the transmission time of the acknowledgment corresponding to the time point and the probe response. In addition, when the received signal is the CTS, the time calculator 350 may calculate the signal time difference t5 illustrated in FIG. 9 by using the reception time of the CTS and the transmission time of the RTS corresponding to the CTS.

The time calculator 350 transmits the calculated signal time difference to the RTT estimator 500 through the interface 310.

Meanwhile, when the RTT estimator 500 is implemented as one device together with the signal time measurer 300, the signal time difference of the signal time measurer 300 may be transmitted to the RTT estimator 500 through an internal interface.

The controller 360 controls the overall operation of the signal time meter 300.

13 is a flowchart illustrating a method of measuring a signal time value in a signal time meter according to an embodiment of the present invention.

Referring to FIG. 13, the antenna 320 detects the signal of the physical layer of the WLAN device 100 and transmits the signal to the reception time detector 330 (S1310).

The reception time detector 330 detects a reception time from the baseband reception signal received and sensed by the antenna 320 (S1320), and transmits the baseband reception signal to the signal detector 340. In addition, the reception time detector 330 transmits the reception time of the baseband reception signal to the time calculator 350.

The signal detector 340 demodulates and decodes the baseband received signal to determine the type of the received signal (S1330), and then transfers the information to the time calculator 350.

The time calculator 350 calculates a signal time difference based on the reception time of the detected reception signal and the reception time of the signal corresponding to the reception signal according to the type of the reception signal (S1340).

The time calculator 350 transmits the calculated signal time difference to the RTT estimator 500 (S1350).

An embodiment of the present invention is not implemented only through the above-described apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Such an implementation can be easily implemented by those skilled in the art to which the present invention pertains based on 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 of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (18)

In a system for measuring round trip time (RTT) based on a wireless local area network (WLAN),
First and second signal times, each connected to two WLAN devices performing WLAN communication, and measuring a signal time difference between a transmission signal from each WLAN device and a received signal of each WLAN device corresponding to the transmission signal; Meter, and
RTT estimator for estimating RTT using signal time difference measured from first and second time meters respectively
RTT measuring system comprising a. In claim 1,
Each of the first and second signal time meters,
A reception time detection unit detecting a transmission time of the transmission signal and a reception time of the reception signal;
A signal detector for determining types of the transmission signal and the reception signal, and
A time calculator configured to calculate a signal time difference required for estimating the RTT by using a transmission time of the transmission signal and a reception time of the reception signal according to the type of the transmission signal and the reception signal;
RTT measuring system comprising a. In claim 2,
Each of the first and second signal time meters,
RTT measurement system further comprises an antenna for detecting the transmission signal of the corresponding WLAN device and the received signal from the corresponding WLAN device to transmit to the reception time detection unit. The method of claim 2,
The signal detecting unit demodulates and decodes the transmission signal and the reception signal to determine the type of the transmission signal and the reception signal. In claim 2,
One of the transmission signal and the received signal includes a probe request or probe response,
If the received signal is a probe request, the transmitted signal includes a probe response; if the received signal is a probe response, the transmitted signal includes an probe request and an acknowledgment for the probe response. system. The method of claim 2,
One of the transmitted signal and the received signal includes a request to send or a clear to send,
The transmission signal includes the transmission confirmation when the received signal is the transmission request, and the transmission signal includes the transmission request when the reception signal is the transmission confirmation. In claim 2,
One of the transmitted signal and the received signal includes a command request or a command response,
The transmission signal includes the command response when the received signal is the command request, and the transmission signal includes the command request when the received signal is the command response. The method of claim 2,
One of the transmitted signal and the received signal comprises data or acknowledgment,
The transmission signal includes the acknowledgment when the received signal is the data, and the transmission signal includes data when the received signal is the acknowledgment. In claim 1,
The RTT estimator is implemented in one of two WLAN devices. In claim 1,
The RTT estimator is implemented in one device together with one of the first and second signal time meters. In a method of measuring RTT using a signal transmitted and received between two wireless local area network (WLAN) devices in a round trip time (RTT) measuring system,
Receiving a transmission signal of a WLAN device connected to itself and a reception signal corresponding to the transmission signal at a first and a second signal time meter respectively connected to two WLAN devices;
Measuring a signal time difference between the transmission signal and the reception signal at a first and a second signal time meter, respectively; and
Estimating an RTT using a signal time difference measured by the first and second signal time meters in an RTT estimator
RTT measuring method comprising a. In claim 11,
The measuring step,
Receiving a transmission signal and a reception signal of a WLAN device connected with the self;
Detecting a reception time of the transmission signal and the reception signal, and
Calculating a signal time difference using a reception time of the received signal and a transmission time of the transmission signal;
RTT measuring method comprising a. In claim 12,
One of the transmitted signal and the received signal includes a probe request or probe response,
If the received signal is a probe request, the transmit signal includes a probe response; if the received signal is a probe response, the transmit signal includes an probe request and an acknowledgment for the probe response. Way. In claim 12,
One of the transmitted signal and the received signal includes a request to send or a clear to send,
The transmission signal includes the transmission confirmation when the received signal is the transmission request, and the transmission signal includes the transmission request when the reception signal is the transmission confirmation. In claim 12,
One of the transmitted signal and the received signal includes a command request or a command response,
The transmission signal includes the command response when the received signal is the command request, and the transmission signal includes the command request when the received signal is the command response. In claim 12,
One of the transmitted signal and the received signal comprises data or acknowledgment,
The transmission signal includes the acknowledgment when the received signal is the data, and the transmission signal includes data when the received signal is the acknowledgment. In claim 11,
And the first and second signal time meters are each directly connected to a corresponding WLAN device by wire or wirelessly. In claim 11,
At least one of the first and second signal time meters is coupled to the RTT estimator via a network.
KR1020110061089A 2010-09-07 2011-06-23 System and method for measuring round trip time based on wireless local area network KR20120025378A (en)

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