KR100780016B1 - Wireless Terminal Eliminates Interference and Interference in the ISM Band - Google Patents

Abstract

The present invention relates to a wireless terminal that eliminates crosstalk and interference in an ISM band. The present invention relates to a wireless terminal that is emitted from another electronic device (microwave oven, medical equipment, etc.) using the same frequency band when transmitting voice data through an existing ISM band. In order to improve the problem of device malfunction or loss of data transmitted in an interference section when interference occurs, a scan section is placed at the end of every superframe in a wireless data network using a frequency hopping scheme (FHSS). Sequentially scan and scan the frequency interference intervals by electromagnetic waves generated from other electronic devices in the ISM band in advance, thereby creating a new jump pattern that avoids the radio interference intervals based on the detected information and transmitting the data by the jump pattern. Crosstalk in the ISM band, thereby preventing data loss and malfunction It is an object of the present invention to provide a wireless terminal that eliminates interference with.

ISM band, wireless terminal, frequency hopping (FHSS)

Description

WIRELESS TERMINAL WITH INDUSTRIAL SCIENTIFIC MEDICAL BAND

1 is a schematic diagram of a conventional superframe structure.

Figure 2 is an exemplary view showing a frequency hopping state during radio wave interference by a conventional wireless terminal.

3 is a superframe structure diagram of a swap applied to a wireless terminal that eliminates crosstalk and interference in an ISM band according to the present invention.

4 is a flow chart showing a frequency hopping process according to the new hop sequence in FIG.

5 is an exemplary diagram illustrating a frequency hopping state during radio wave interference of a wireless terminal in which crosstalk and interference are eliminated in an ISM band according to the present invention.

The present invention relates to a signal transmission method that avoids radio wave interference. In particular, in a wireless data system using a frequency hopping scheme (FHSS), a scan section is provided at the end of each superframe, and the transmitting side is another electronic device in the ISM band. A signal transmission method that avoids radio interference by detecting a frequency interference section in advance whether or not an electromagnetic wave is generated from and receiving a new jump pattern that avoids a radio interference section by transmitting the data accordingly. It is about.

In general, the frequency range of the 2.4 GHz band is a region allocated to a wireless LAN in Korea, and is a frequency band that is permitted to be used without a license by the general public. Therefore, the wireless communication system operating in the ISM band can be used not only in domestic logistics automation system, WLL, information exchange system, but also in many countries including the United States, and its scope of application is wide.

The spread spectrum using the 2.4 GHz band includes a direct sequence spread spectrum (DSSS) and a frequency hopping spread spectrum (FHSS).

Among them, DSSS is a method of obtaining a spread signal by directly multiplying a spreading code by data, and FHSS is a method of shifting a frequency band according to spreading code.

In particular, the frequency hopping method is a method in which the carrier frequency of a signal to be spread is hopped and transmitted at regular time intervals according to the hopping pattern. The frequency hopping method converts a narrowband signal into a wideband signal with a time average.

This frequency hopping method creates a random hop pattern within an Industrial Scientific Medical (ISM) band that meets the standards of each country, transmits data at the frequency that matches the pattern, minimizes frequency duplication, and multi-paths with fast frequency conversion. It has a merit of low loss and simple configuration, and is widely used in low-cost wireless LAN.

Then, as one of the frequency hopping schemes described above, a shared wireless access protocol (SWAP), which is a home RF standard wireless data transmission method to be used for a home network, will be described with reference to FIG. 1.

1 shows a conventional superframe structure of a swap method, and as shown therein, a hop period (Hop) for hopping frequency; Beacon period (Beacon) for conveying information about the frequency pattern to jump, hop index and dwell time;

A voice retransmission section CFP1 for retransmitting a voice when an error occurs in the data of the voice transmission section CFP2; A data transmission section (CP) for transmitting data; It consists of a voice transmission section (CFP2) for transmitting voice. The structure of the superframe has a period of 20msec unlike the wireless LAN.

However, as described above, when there is an electronic device (eg, a microwave oven) using an ISM band within a distance of an effective field strength (RSSI: Return Signal Strength Indicator) of data transmitted in a swap method, as shown in FIG. Likewise, interference caused by electromagnetic waves generated by the microwave oven is received. Accordingly, the transmission data is recognized as indistinguishable data and is retransmitted, if the data retransmitted on the wireless terminal is a character. In case of files or files, time constraints are less, but voice data, which must be transmitted in real time, causes a great damage to call quality.

When transmitting voice data through this ISM band, if interference occurs due to electromagnetic waves emitted from other wireless terminals (DMB phones, PDAs, laptops) using the same frequency band, it may cause device malfunction or There was a problem that can lose the transmitted data.

Accordingly, the present invention has been made to solve the above-mentioned problems, the user's wireless terminal is detected in advance by scanning the frequency interference interval caused by electromagnetic waves generated from other electronic devices in the ISM band by scanning It is an object of the present invention to provide a signal transmission method that avoids radio wave interference in which data is transmitted by a new hop pattern so as to avoid it.

In order to achieve the above object, the wireless terminal removes the interference and interference in the ISM band according to the present invention,

Wireless data system using frequency hopping (FHSS),

A first step of further including a scan section at an end of the superframe for wireless transmission; A second step of sequentially scanning and detecting, by channel, a frequency interference section caused by electromagnetic waves generated from another electronic device in an industrial scientific medical band during the scan period;

Generating a new jump pattern for avoiding the radio interference section by the sensed information;

This is achieved by the fourth step of transmitting data by the newly generated jump pattern.

Hereinafter, described in detail with reference to the accompanying drawings of the present invention.

First, the ISM band (Industrial Scientific Medical Band) will be described.

The ISM band (Industrial Scientific Medical Band), originally part of the FCC regulations in the United States, is an industry-licensed and medical-use band that was originally unlicensed with weak field strengths, and is primarily 900 MHz (902 MHz to 928 MHz), 2.4 GHz (2.4 GHz). ~ 2.4835 GHz) and 5.8 GHz (5.725 GHz to 5.825 GHz) are most actively used for wireless LAN applications.

Since it is a license-free band, it can be used for free data communication, can be used all over the world, is easy to install, and can be configured in a small network in a home that can be freely deployed.

Representative wireless LAN standards using the ISM band include 2.1 Bluetooth, HomeRF, IEEE802.11, IrDA, and HIPERLAN.

Method name Bluetooth IEEE 802.11 Home RF IrDA HIPERLAN Transmission speed 1 Mbps (actually 721 kbps) 2 Mbps (IEEE 802.11b: 11 Mbps) 0.8 Mbps, 1.6 Mbps 4 Mbps (advanced IR: 16 Mbps) 23.5 Mbps Frequency band 2.4 GHz band 2.4 GHz band 2.4 GHz band infrared ray 5 GHz vs 17 GHz Modulation method Frequency hopping spread spectrum technology (hopping frequency up to 1600 times per second) Direct spreading and frequency hopping spread spectrum technology Frequency hopping spread spectrum technology (hopping frequency up to 50 times per second) 4-step PPM / 16-step PPM (primary modulation only) Frequency hopping spread spectrum technology Dedicated Voice Channel (Coding by CSVD or logarithmic PCM) radish radish radish 32 kbps ADPCM Transmission distance 10 m (1 mW, 0 dBm), 100 m (100 mW, +20 dBm) 100m (30m for 802.1b) 50 m 3.8m 30 m Primary Modulation GAUSSIAN Freq.Shift Keying (GMSK) BPSK / QPSK and GFSK GFSK remind Diff. GMSK Connection control method Master-Slave, Polling CSMA / CA CSMA / CA, TDMA Pplling EY-NPMA security Standard (Authentication, Encryption) option Standard (Encryption) radish NA

 The present invention provides a wireless terminal which eliminates crosstalk and interference in such an ISM band.

3 is a diagram illustrating a superframe structure of a swap applied to a wireless terminal which eliminates crosstalk and interference in an ISM band according to the present invention.

It is a hopping period (Hop) for hopping the frequency; Beacon period (Beacon) for conveying information about the frequency pattern to jump, hop index and dwell time; A voice retransmission period (Contention Free Period: CFP1) for retransmitting a voice when an error occurs in data of the voice transmission period (Contention Free Period: CFP2); A data transmission period (CP) for transmitting data; In the superframe structure composed of a voice transmission interval (CFP2) for transmitting voice,

The frame end further includes a scan section for sequentially measuring the electric field strength in the ISM band for each channel.

Hereinafter, specific operations and operations of the wireless terminal which eliminates crosstalk and interference in the ISM band according to the present invention will be described.

First, by measuring the electric field strength in the scan section of each end of the superframe having a period of 20msec, and by checking the presence of the sync bit, it is possible to know the distribution and the intensity of electromagnetic waves generated in the heterogeneous electronic devices. .

In other words, the scan section scans and emits radio waves from the transmitting side to the receiving side over the entire frequency band as if it were a radar, and measures the electric field strength of the received radio wave at the receiving side to detect whether there is radio interference. And not transmitting the hop pattern change command, but transmitting the radio wave from the heterogeneous electronic device over the entire frequency band during the scan period by the transmitting side.

In other words, instead of changing the frequency hopping pattern due to a reception error on the receiving side, the hopping pattern is changed in advance because the hopping pattern is changed in advance by whether or not electromagnetic waves from other electronic devices are received within the entire frequency channel section by the transmitting side itself. There is no need to detect if there is an interference interval.

In this case, the electric field strength is down-converted to an IF signal as a method adopted by almost all communication equipments, and the voltage value of the demodulated DC level signal is measured by the demodulator. You will know.

However, in the frequency hopping method, since the changing hopping frequency information is also known to the receiver side, the IF frequency is changed to a constant frequency by performing the down-conversion while changing the frequency of the local oscillator embedded therein. The measured signal strength is stored in a memory (not shown) and used as a data to make a new jump pattern that avoids a radio wave interference section next time. If the equipment using the ISM band is an electronic device such as a microwave oven, not a communication device, the period of the new leap pattern may be relatively long since the radio interference time is much longer than that of the communication device.

Next, a method of obtaining and applying the new jump pattern as described above will be described with reference to the flowchart of FIG. 4.

First, the basic process is to scan at the end of every superframe in the wireless data network using the frequency hopping scheme (FHSS), and to measure the return signal strength indicator (RSSI) in each ISM band for each frequency channel. Measured sequentially (ST1) and stored in the memory (not shown).

Next, the distribution and intensity of the electromagnetic wave occupied in the ISM band are determined by referring to the scan table (RSSI table) stored as described above (ST2), and if there is no radio wave distribution of the wireless terminal (ST3), the original normal jump sequence is performed. The channel is hopped by (ST5).

However, if a block-level frequency distribution is detected by the operation of a wireless terminal such as a DMB phone, if the radio wave distribution is narrow, the jump sequence is reconfigured to a channel outside the radio interference interval of the wireless terminal, and if the radio wave distribution is wide, the channel strength is low. The leap sequence is reconfigured (ST4).

At this time, frequency hopping is performed according to the new hopping sequence, thereby avoiding mutual interference with radio waves generated from the wireless terminal (ST6).

Here, the process of detecting the radio wave of the radio terminal will be described in more detail as follows. For example, the receiver of the hopping system transmits all frequencies in the frequency interval by 1 MHz every scan period located at the end of every superframe. The frequency is shifted in sequence, and the electric field strength at that frequency is measured. The measured frequency and the electric field intensity information are stored in a table in the form of a table (scan table creation).

The frequency hopping information is analyzed using the stored frequency and the electric field strength information, and it can be distinguished from a communication device using a method of leaping at an arbitrary frequency or a device occupying a broadband such as a microwave oven. (Wireless terminal detection)

In general, communication equipment using frequency hopping communicates by moving in an arbitrary frequency pattern with a frequency interval of 6 MHz or more.

If the equipment using the ISM band does not use the frequency hopping method, it can be easily distinguished because it occupies a certain frequency band and communicates like the DSSS (Direct Sequence Spread Spectrum) method.

Accordingly, when the equipment having the scanned information occupies adjacent frequency bands and emits a certain electric field strength or more is detected, the frequency bands are identified and other jump patterns are made to the bands out of this to communicate. Frequency avoidance)

In this way, after checking the operation and distribution of the radio terminal by periodic channel scan, if there is no radio interference section, the radio waves generated by the radio terminal (for example, DMB phone) as shown in FIG. Since it does not overlap with the interference interval, data can be transmitted without loss of data.

As described above, when the wireless terminal removes the crosstalk and the interference in the ISM band according to the present invention, the transmitting side uses the ISM band to transmit frequency interference intervals caused by electromagnetic waves generated from other electronic devices within the ISM band. By transmitting the data by a new jump pattern that detects the scan in advance and avoids the section, data loss and malfunction can be prevented.

Claims (2)

A first step of further including a scan section in a swap (SWAP) of a home RF system which is an end of a superframe for wireless transmission; A second step of sequentially scanning a frequency interference section due to electromagnetic waves generated from heterogeneous electronic devices in an Industrial Scientific Medical (ISM) band during each scan period for each channel in advance; A third step of generating a new hopping pattern that avoids the propagation interference interval based on the detected information; In the fourth step of transmitting data by the newly generated jump pattern, The hopping pattern generation process includes a first step of sequentially scanning a field strength (RSSI) in an ISM band to be used for each frequency channel through a frequency hopping method (FHSS) to generate a scan table; A second step of identifying distribution and intensity of electromagnetic waves of the wireless terminal occupied in the ISM band by referring to the scan table of the electric field strength; A third step of judging whether the radio terminal interferes with the radio wave based on the electromagnetic wave distribution and the intensity detected in the second step; A fourth step of transmitting data according to the original normal jump pattern when there is no radio interference by the wireless terminal as a result of the determination; If there is a radio wave interference by the wireless terminal as a result of the determination, there is a fifth step of transmitting data by reconstructing the hopping pattern to a new channel having no radio wave interference interval due to the electric field strength distribution. Signal transmission method of a wireless terminal with the interference removed. delete

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