KR20030083050A - Frequency scanning apparatus and method for a dedicated short range communication - Google Patents

Abstract

PURPOSE: A frequency scan device for short range wireless communication is provided to automatically scan a using frequency of a base station within a communication cell even though a user moves between communication cells, thereby smoothly supplying a communication service of the base station. CONSTITUTION: A CPU(100) inputs and outputs data for frequency scanning performed when a user moves between base stations using different frequencies. A frequency scan control unit(300) inputs the data from the CPU(100), and searches a using frequency of a specific base station providing a predetermined service within a current communication cell. A wireless communication unit(200) is controlled by the frequency scan control unit(300), and transceives a communication frame of the using frequency from the specific base station.

Description

Frequency scanning apparatus for short range wireless communication and frequency scanning method using same {Frequency scanning apparatus and method for a dedicated short range communication}

The present invention relates to an apparatus and method for scanning a frequency selected on a dedicated short range communication (DSRC) protocol, which is a short-range wireless communication standard between a roadside base station and a wireless communication terminal installed in a vehicle.

In general, a short range wireless communication system includes a plurality of small geographic areas, commonly referred to as 'cells', wherein a user-side wireless communication terminal in each communication cell provides a service by communicating with a base station using a predetermined communication protocol. You will be provided. In order to receive a service provided from such a short-range wireless communication system, a wireless communication terminal operates only at a single frequency transmitted from a base station of a predetermined carrier.

Meanwhile, among protocols applied to a short range wireless communication system, the DSRC protocol may support various intelligent transport systems (ITS) services such as an automatic toll collection system (ETC) as well as a traffic information and control system. The communication according to the DSRC protocol currently has a bandwidth of 10 MHz in the 5.8 GHz band and uses ASK (Amplitude-Shift Keying) demodulation method. In case of one-to-one communication in the lane, different band frequencies should be used between adjacent base stations to prevent communication interference between base stations. In this case, the wireless communication terminal should scan the frequency to find the frequency in the communication cell in which the vehicle is located.

However, since the existing wireless communication terminal is implemented to operate only at a single frequency, it is impossible for the user to receive service when the frequency in the current communication cell where the vehicle (ie, the wireless communication terminal) is located is different from the use frequency of the wireless communication terminal. . Accordingly, when the adjacent communication cells are serviced at frequencies of different bands, consumers need an apparatus for finding a frequency that can be serviced by a base station while moving.

SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency scan apparatus for short-range wireless communication and a frequency scan method using the same, which can solve the above-mentioned problems of the prior art to meet the needs of consumers.

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a block diagram illustrating a configuration of a frequency scan apparatus for short-range wireless communication according to the present invention.

FIG. 2 is a diagram for describing a dedicated short range communication (DSRC) communication frame transmitted in short range wireless communication.

3 is a flowchart illustrating a frequency scan method for short-range wireless communication according to the present invention.

FIG. 4 is a flowchart illustrating an initial register setting method of FIG. 3.

<Description of Symbols for Main Parts of Drawings>

100: central processing unit 200: wireless communication unit

300: frequency scan control unit 310: data storage

320: scan processor 330: frequency synthesis controller

340: change timer 350: rescan timer

360: clock generator

One aspect of the present invention for achieving the above technical problem relates to a frequency scanning device applied to the apparatus for short-range wireless communication. According to an aspect of the present invention, there is provided a frequency scanning apparatus comprising: central processing means for inputting and outputting data for frequency scanning performed during movement between base stations using different frequencies; Frequency scan control means for receiving the data from the central processing means and finding a frequency used by a specific base station for providing a predetermined service in a current communication cell; And wireless communication means, controlled by the frequency scan control means, for transmitting and receiving a communication frame of the used frequency to / from the specific base station.

Another aspect of the present invention for achieving the above technical problem relates to a frequency scanning method of a device for short-range wireless communication. According to another aspect of the present invention, there is provided a frequency scanning method comprising: (A) setting scan data including a plurality of frequencies to be used for the frequency scan; (B) driving a timer to check whether a communication frame is detected from a specific base station providing a service in a current communication cell in which the communication device is located; (C) in step (B), if it is determined that the communication frame is not detected within a predetermined time, performing step (B) using the next frequency to be used for the scan among the set scan data; ; And (D) in step (B), when the communication frame is detected, causing the communication device to communicate with the specific base station at the frequency used when detecting the communication frame.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. And, before describing the present invention in detail, it will be understood that the frequency scanning apparatus and method of the present invention described below can be applied to all the wireless communication terminal (hereinafter referred to as "communication terminal") to communicate according to the DSRC protocol.

Hereinafter, a frequency scan apparatus for short range wireless communication and a frequency scan method using the same will be described in detail with reference to FIGS. 1 to 4.

1 is a block diagram illustrating a configuration of a frequency scan apparatus for short-range wireless communication according to the present invention. Referring to FIG. 1, a frequency scan apparatus according to the present invention includes a central processing unit (CPU) 100, a wireless communication unit 200, and a frequency scan control unit 300. Here, the CPU 100 and the frequency scan control unit 300 may be implemented on one digital board.

The CPU 100 outputs data for the operation of the frequency scan control unit 300 (that is, use frequency scan of a base station providing a service in the current communication cell in which the communication terminal is located) to output the data of the frequency scan control unit 300. Write to data store 310. In addition, the CPU 100 may read data recorded in the data storage 310.

The wireless communication unit 200 includes a frequency synthesizer 210 and is controlled by the frequency scan control unit 300 to receive a DSRC communication frame transmitted from a roadside base station (or apparatus) at a set frequency, and to communicate. Transmit the DSRC communication frame transmitted from the terminal. The DSRC communication frame includes one frame control slot (FCMS), n message data slots (MDS), and k connection request slots (ACTS), as shown in FIG. Here, the FCMS is information transmitted from the roadside base station to the communication terminal and has a unique frame synchronization signal (FSW) composed of 32 bits. The MDS is information transmitted from a roadside base station or a communication terminal, the ACTS is information transmitted from a communication terminal to a roadside base station, and each of the MDS and ACTS has a unique channel synchronization signal (CSW) composed of 16 bits. In this embodiment, n is an integer of 0≤n≤8, k is an integer of 0≤k≤8, and the sum of MDS and ACTS included in one DSRC communication frame is greater than 1 or 1 And less than 8 or equal to 8 (ie 1 ≦ n + k ≦ 8). Accordingly, the DSRC communication frame in this embodiment transmitted from the base station includes one FCMS and has a slot length of at least two slot lengths up to nine slot lengths.

The frequency scan control unit 300 includes a data store 310, a scan processor 320, a frequency synthesis controller 330, a change timer 340, a rescan timer 350 and a clock. The generator 360 scans a frequency according to data input from the CPU 100 to find a frequency used by a base station that provides a service in a communication cell in which a communication terminal is currently located.

The data store 310 receives and sets data from the CPU 100 to perform a frequency scan, which includes a plurality of frequencies to be used for the scan. At this time, the apparatus of the present invention performs a frequency scan according to the data set in the data store 310. This data store 310 is, in this embodiment, a data area for the change timer 340 and the rescan timer 350, an area for storing a frequency to be used for scanning, and an intermediate frequency (IF). ), An area for storing the data value of the frequency synthesizer, and the like. Further, the data store 310 is configured with 16 bits in this embodiment, but may be configured with 32 bits in another embodiment of the present invention.

In this case, the data area for the change timer 340 and the rescan timer 350 uses a unit of 1 bit as an octet, and is configured to be programmed up to 128,000 octets.

In the region for storing the frequency to be used, a frequency used as a 10 MHz bandwidth from a start frequency is denoted by 1. For example, in the area for storing the frequency to be used, 5.80 Hz, 5.81 Hz, 5.84 Hz and 5.85 Hz are denoted by the values of 1100110000000000.

The area for storing the IF (Intermediate Frequency), when setting the data storage 310, not only selects the IF in consideration of compatibility with the wireless communication unit 200, but also decides whether to use the top or the bottom of the IF. It is configured to set whether or not to use. That is, it may be implemented to set one up and down selection bits to set whether to use the top or the bottom of the IF. For example, when the transmission frequency of the roadside base station is 5.80 kHz and the IF is 70 MHz, 5.87 kHz may be set as the reception frequency for performing the scan according to the value of the up / down selection bit, and 5.73 kHz may be set. It may be. In this case, IF selection is determined according to the value of the bit. For example, if the bit is [3: 0], it is 30 MHz for 0001, 40 MHz for 0010, and 170 for 1111. MHz.

In the area for storing the data value of the frequency synthesizer 210, a plurality of frequencies and / or related data to be used for scanning are sequentially set, including the initial transmission frequency of the communication terminal. The area for storing data values of the frequency synthesizer 210 is preferably designed in consideration of compatibility with various types of frequency synthesizer 210. In other words, since the number of setting data is different for each manufacturer of the frequency synthesizer 210, the area for storing the data value of the frequency synthesizer 210 preferably includes a register for managing the number of data of the frequency synthesizer 210. Do.

The scan processor 320 is driven when data is set in the data storage 310 and a frequency scan is started. The scan processor 320 processes the data into a predetermined form so as to have a format of data in each state according to a predetermined scan algorithm. To sequentially set the frequency synthesis controller 330. Specifically, the setting values of the timers 340 and 350 from the CPU 100 to the data store 310, the frequency to be used, the IF, the data value of the frequency synthesizer 210, and the number of bits of the frequency synthesizer 210. When scan data such as the above is set, the scan algorithm of the scan processor 320 sets the frequency synthesis controller 330 to use the frequency for the scan. For example, when scanning the upper frequency of the IF, the scan algorithm calculates and sets the transmission frequency + (plus) IF in the frequency synthesis controller 330, and when scanning the lower frequency of the IF, the scan The algorithm calculates the transmission frequency-(minus) IF and sets it in the frequency synthesis controller 330. After the scan processor 320 first sets data relating to the frequency to be scanned in the frequency synthesis controller 330, the timer In response to a detection failure signal (that is, a scan failure signal) to be described later generated from the fields 340 and 350, data such as a frequency to be used for the next scan is set in the frequency synthesis controller 330. Here, the number of frequencies to be scanned of the scan algorithm may vary depending on the operation of the data store 310.

When the frequency to be scanned is set, the frequency synthesis controller 330 sets a frequency to be scanned in the frequency synthesizer 210 of the wireless communication unit 200 and generates a scan operation signal for driving the change timer 340. .

The change timer 340 operates when a frequency to be used for the frequency synthesis controller 330 is set to generate a scan operation signal, and detects the FSW or CSW of the DSRC communication frame received by the wireless communication unit 200. That is, frequency scan is performed. At this time, when the FSW or CSW is detected, the change timer 340 generates a predetermined detection signal and terminates the operation as finding the transmission (ie, use) frequency of the roadside base station. In this case, the communication terminal to which the apparatus of the present invention is applied can communicate the DSRC communication frame with the roadside base station. On the other hand, if the FSW or CSW is not detected even after a predetermined time has elapsed, the change timer 340 generates the detection failure signal as the transmission frequency of the roadside base station is not found. At this time, a different scan frequency is set in the frequency synthesis controller 330, and the change timer 340 detects the FSW or CSW again.

The rescan timer 350 is driven in response to the detection signal of the change timer 340 after the frequency scan is finished (i.e., after the FSW or CSW is detected by the change timer 340). By detecting the FSW of the DSRC communication frame received at 200, the communication terminal monitors whether it is still in the communication cell of the base station using the scanned frequency. The rescan timer 350 is reset when the FSW is detected, and performs the FSW detection operation again. On the other hand, when the communication terminal is transported to a communication cell of another base station using a different frequency and the FSW is not detected for a predetermined time, the scan timer 350 generates the scan failure signal and ends the operation. At this time, the frequency scan as described above is performed again.

The clock generator 360 divides the system clock signal CLK input from the outside to generate the internal clock signal ICLK required for the operation of the scan processor 320.

Next, a frequency scan method for short-range wireless communication of the present invention will be described in detail with reference to FIGS. 3 and 4. As shown in FIG. 3, first, scan data is input to the data store 310 and set by the CPU 100 (S410). The setting step (S410) is described in detail with reference to Figure 4, the data for the timers (340, 350) is set (S411), the frequency to be used for scanning is selected (S413), IF is selected (S415), the data and the number of bits of the frequency synthesizer 210 are sequentially set (S417, S419). At this time, the data storage 310 first sets the initial scan frequency to the frequency synthesis controller 330 by transmitting data related to the frequency to be used for the frequency scan to the scan processor 320 (S420).

In this case, the frequency synthesis controller 330 sets the set initial scan frequency to the frequency synthesizer 210 of the wireless communication unit 200 and generates the scan operation signal to drive the change timer 340 (S430). .

At this time, the change timer 340 checks whether the DSRC communication frame is received by the wireless communication unit 200 to detect the FSW or CSW (S440). In the check step (S440), if it is confirmed that the FSW or CSW is not detected for a predetermined time, the change timer 340 generates a detection failure signal and ends the operation (S450).

On the other hand, in the check step (S440), if it is confirmed that the FSW or CSW is detected, the change timer 340 generates a frame detection signal to drive the rescan timer 350 (S460), the operation Quit. Then, the rescan timer 350 detects the FSW of the DSRC communication frame received by the wireless communication unit 200, thereby monitoring whether the communication terminal is in the communication cell of the base station using the currently scanned frequency. Specifically, in response to the detection signal of the change timer 340, the rescan timer 350 checks whether the FSW of the DSRC communication frame is detected (S470), and if it is confirmed that the FSW is detected, reset it. In step S480, the step S470 of checking whether the FSW is detected is repeatedly performed. On the other hand, in the check step (S470), when it is confirmed that the FSW has not been detected for a predetermined time, the rescan timer 350 generates the detection failure signal and ends the operation (S490).

In operation S450 or S490, when a detection failure signal is generated from the change timer 340 or the rescan timer 350, the scan processor 320 is set in the data store 310 according to a scan algorithm. It is checked whether there is data related to the frequency to be used for the next scan among the scan data, and it is checked whether all scans have been used up to the last frequency set in the data storage device 310 (S500).

In the checking step (S500), since the frequency used for driving the change timer 340 in the step S430 is the last frequency stored in the data storage 310, it is confirmed that there is no data related to the next scan frequency. In this case, the scan processor 320 determines whether it is no longer possible to perform a frequency scan due to a power off (S510). If it is determined in step S510 that it is no longer possible to perform a frequency scan, the apparatus of the present invention ends the operation. On the other hand, if it is possible to continue the frequency scan in the determination step (S510), the initial frequency setting step (S420) is performed.

On the other hand, in the check step (S500), if it is confirmed that the next scan frequency exists, the scan processor 320 sets the next scan frequency to the frequency synthesis controller 330 (S520). In this case, the frequency synthesis controller 330 sets the next scan frequency to the frequency synthesizer 210 of the wireless communication unit 200 and generates the scan operation signal to drive the change timer 340 (S430). ).

According to the frequency scan apparatus and method for short-range wireless communication according to the present invention as described above, by performing the communication by scanning the frequency of use of the base station, even while moving the communication cells serviced by the base stations using different frequencies You can get services.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. For example, in another embodiment of the present invention, an area for determining whether to use a scan may be provided in the data storage 310 to select a case of operating at a fixed frequency and a case of performing a scan. In another exemplary embodiment of the present invention, when performing a scan, communication is performed while setting a data value of the frequency synthesizer, and only a data value of the frequency synthesizer is set when no scan is performed. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the frequency scanning apparatus and method for short-range wireless communication of the present invention as described above, even if a user having a communication terminal moves between communication cells serviced by base stations using different frequencies, the present invention is automatically applied. Since the use frequency of the base station in the communication cell located is scanned, it is possible to smoothly receive the communication service provided from the base station.

Claims (8)

In the device for short-range wireless communication, Central processing means for inputting and outputting data for frequency scanning performed during movement between base stations using different frequencies; Frequency scan control means for receiving the data from the central processing means and finding a frequency used by a specific base station for providing a predetermined service in a current communication cell; And Wireless communication means controlled by said frequency scan control means for transmitting and receiving a communication frame of said used frequency to / from said specific base station; Frequency scanning device for short-range wireless communication, characterized in that it comprises a. The method of claim 1, wherein the frequency scan control means A data storage unit for storing and setting data input from the central processing unit; When the data is set in the data store, the data is processed and output in a predetermined form according to a predetermined scan algorithm for finding a frequency of the specific base station, but when a scan failure signal is input from the outside, A scan processor for outputting data; A frequency synthesizing controller which receives a predetermined type of data output from the scan processor, sets a frequency to be scanned in the wireless communication means, and generates a predetermined scan operation signal; And It is driven in response to the scan operation signal, and confirms whether a communication frame of the use frequency is input to the wireless communication means, and when it is confirmed that the communication frame of the use frequency is input, the communication frame of the use frequency is continued. A timer for generating the scan failure signal if it is determined that the communication frame of the frequency is not input for a predetermined time. Frequency scanning device for short-range wireless communication, characterized in that it comprises a. The method of claim 2, wherein the timer It is checked whether the communication frame of the use frequency is input to the wireless communication means, and when it is confirmed that the communication frame of the use frequency is input, a predetermined detection signal is generated, and the communication frame of the use frequency for the predetermined time. A first timer for generating the detection failure signal when it is determined that the input signal is not inputted; And By detecting the communication frame received by the wireless communication means in response to the detection signal of the first timer, it is monitored whether the communication device is in the communication cell of the base station using the currently scanned frequency, and the communication frame is If not detected, the second timer for generating the detection failure signal Frequency scanning device for short-range wireless communication, characterized in that it comprises a. The method of claim 2 or 3, wherein the frequency scan control means And a clock generator for dividing a clock signal input from the outside to generate an internal clock signal for the operation of the scan processor. In the frequency scanning method using a device for short-range wireless communication, (A) setting scan data including a plurality of frequencies for use in the frequency scan; (B) driving a timer to check whether a communication frame is detected from a specific base station providing a service in a current communication cell in which the communication device is located; (C) in step (B), if it is determined that the communication frame is not detected within a predetermined time, performing step (B) by setting a next frequency to be used for the scan among the set scan data; ; And (D) in step (B), when the communication frame is detected, causing the communication device to communicate with the specific base station at the frequency used when detecting the communication frame. Frequency scanning method for short-range wireless communication, characterized in that it comprises a. The method of claim 5, wherein step (D) (D1) further checking whether the communication frame is continuously detected, and monitoring whether the communication device is located in a current communication cell serviced by the specific base station, In step (D1), if it is determined that the communication frame has not been detected for a predetermined time, frequency scan for short-range wireless communication is performed again using step (B) using data for another scan. Way. The method of claim 5 or 6, wherein step (A) (A1) setting the scan data in a data store; And (A2) setting scan data to be used for the initial scan among scan data stored in the data storage device; Frequency scanning method for short-range wireless communication, characterized in that it comprises a. The method of claim 7, wherein step (A1) (A11) setting data related to the timer; (A12) setting a plurality of frequencies to use for the scan; And (A13) A method for scanning a short range wireless communication, comprising setting a predetermined intermediate frequency.