KR20100090942A - Local area wireless communication system for transmitting voice with interference avoidance - Google Patents

Abstract

PURPOSE: A local wireless communication system having interference function is provided to explore a clean channel in a clean channel explorer and determine a frequency for master and slave wireless terminal, thereby transmitting a voice signal through clean frequency channel in each wireless terminal. CONSTITUTION: A clear channel search unit(C) extracts a plurality of clean channel by each hopping cycle. A master wireless terminal(M) constructs a frequency table by clean channel information. The master wireless terminal determines a frequency channel. One or more slave wireless terminals construct a frequency table which is the same as the master wireless terminal. The slave wireless terminals determine a frequency channels by a random value of the master wireless terminal.

Description

Local area wireless communication system for transmitting voice with interference avoidance

The present invention relates to a short-range wireless voice communication system having an interference avoidance function. In particular, the present invention relates to a short-range wireless voice communication system. A short range wireless voice communication system having an interference avoidance function for preventing delay, distortion, or disconnection.

Various low power wireless terminals have been developed and used using ISM (Industrial, Scientific, Medical) band band that can be used without permission worldwide. In Korea, the 2.4 GHz band and the 5.7 GHz frequency band are open for licence-exempt output under conditions that meet the criteria set forth in the Radio Law.

Accordingly, the development of wireless multimedia products that can transmit and receive wireless audio signals from wireless headphones, wireless microphones or wireless speakers, and wireless video signals from wireless surveillance cameras or wireless internet broadcasts at a short distance using the frequency band are being actively conducted. . However, this frequency band is allowed to be used by anyone without a license without any use restrictions, so that various application products can be used in the same area, and in this case, severe transmission quality degradation may occur due to frequency interference between various products. Can be. In addition, even when used as a single wireless terminal without such frequency interference, since the wavelength of the used frequency band is 15 cm or less, fading phenomenon occurs due to the multipath signal of the reflected wave by surrounding facilities and furniture, and thus, the transmission quality is deteriorated. The symptoms are serious.

Meanwhile, Bluetooth and Wireless LAN (WLAN) are the representative technologies for short range wireless multimedia transmission methods used in the 2.4 GHz ISM band. However, Bluetooth technology prevents degradation of transmission quality due to mutual interference. However, even if there is interference of a specific frequency by using the frequency hopping method, the data can be transmitted reliably by changing the frequency of use.However, in case of a frequency collision between users in a real-time multimedia signal transmission, the retransmission method reduces the transmission quality. Since Bluetooth cannot be solved, Bluetooth is not suitable for high quality multimedia transmission. Next, the wireless LAN technology has a variable frame multiple access structure, which is not suitable for high-quality multimedia transmission because of its ability to maintain a constant speed at all times, and is not suitable for use in a wireless terminal that has a high power consumption due to high power consumption. Due to the large bandwidth occupied, there is a problem that the number of users that can be used simultaneously in the same area is limited.

In addition, in wireless communication services, many users are required to share the audio device with one or more other users wirelessly in order to receive an audio source only by 1: 1 connection with the audio device, and furthermore, simultaneously or simultaneously with the playback of the audio source. It has led to demands to communicate with other users wirelessly.

In view of this, Korean Patent Publication No. 10-2008-96097 (hereinafter referred to as 'prior art') proposes a multi-party wireless communication system which allows a wireless communication of a plurality of wireless terminals without interference. The technology uses orthogonal hopping to prevent frequency collisions.

1 is a block diagram of a wireless terminal according to the prior art, Figure 2 is a block diagram of the RF module in Figure 1, Figure 3 is a diagram showing a frequency table for orthogonal hopping in the prior art.

As shown in FIG. 1, the wireless terminal according to the related art is an RF module 700, a modem 702, a controller 704, a mode switcher 706, an audio codec 708, a speaker 710, and a microphone. And 712.

In the above-described configuration, the RF module 700 receives a high frequency signal transmitted at a predetermined frequency from another wireless terminal, and also transmits a high frequency signal of an audio sound source provided by a user voice or an audio device connected to the wireless terminal at a predetermined frequency. In order to perform a function, according to the prior art, the wireless terminal applies an orthogonal hopping scheme to prevent frequency collision. Next, the modem 702 is composed of a reception area 702-1 and a transmission area 702-2, where the reception area 702-1 and the transmission area 702-2 are modes of a wireless terminal. (Refer to the prior art publication) to transmit and receive data in different time slots.

The reception area 702-1 performs a process of demodulating the received high frequency signal into a baseband signal when the RF module 700 selectively receives an audio sound source or a user voice transmitted from another wireless terminal. On the other hand, the transmission area 702-2 performs a process of modulating the user's voice into a high frequency signal.

The controller 704 controls the frequency selection process of the RF module 700 and the overall modulation and demodulation of the modem. The mode switching unit 706 corresponds to a user interface. Preferably, the mode switching unit 706 is connected to a button for mode switching on the wireless terminal, and transmits a mode switching signal of the user to the control unit 704. Accordingly, the controller 704 controls the RF module 700 to selectively receive a different frequency signal than before.

Finally, the audio codec 708 is connected to the speaker 710 and the microphone 712 and decodes the audio sound source or user voice demodulated into a baseband signal according to a preset algorithm. Is played through. The audio codec 708 also functions to encode an audio sound source provided by a user voice or an audio device connected to a wireless terminal and transmit it to the modem 702.

Next, an orthogonal hopping and wireless network protocol according to the prior art will be described in detail.

2 shows a detailed configuration of the RF module 700 for orthogonal leap of frequency in software or hardware. As shown in FIG. 2, the RF module 700 includes a frequency table 800 and a frequency sounding ( 802, hop sequence generator 804, and offset adder 806. Hereinafter, the RF module 700 is described as including the configuration shown in FIG. 2, but the components of FIG. 2 may be connected to the RF module 700 while being configured separately from the RF module 700.

In the above-described configuration, the frequency table 800 stores information about an optimum frequency selected as having a good reception sensitivity among the frequencies available for wireless communication. Preferably, the frequency table 800 is set to 0 to 15 as shown in FIG. It can have an address value. Frequency sounding 802 checks the propagation strength and ambient noise of all available frequencies. According to this, when a plurality of wireless terminals are provided, at least one may be set as a master that is in charge of synchronous control, and the other may be set as a slave operating under control of the master.

In this case, the frequency table may be determined by the master, and the slave may receive frequency table information from the master and maintain the same frequency table.

In FIG. 3, the fourth frequency among 79 frequencies is stored as Frq (4) at the frequency table '0', and the seventh frequency is stored as Frq (7) at the '1' address. In this manner, the Frq 79, that is, the 79th frequency is stored at the '15' address.

Meanwhile, the hopping sequence generator 804 outputs randomly one of the values '0' to '15' by a predetermined algorithm every cycle. In FIG. 3, '7' is output in the t th cycle, and (t + 1) In the second cycle, '3' is outputted. The group master with an offset of '0' uses the value output from the hopping sequence generator 804 as the address of the frequency table as it is, so the random address Fadd (0, t) value output at the time 't' is '7'. The 38th frequency Frq (38) addressed with 'is used for the user interval of the cycle. In the same way, the 18th frequency Frq (18) addressed to the random address Fadd (0, t + 1) value '3' output at the time 't + 1' is used for the user section of the cycle.

In the frequency table of the figure, the random address of the 't' time of the wireless terminal with the offset '3' becomes Fadd (3, t) = Fadd (0, t) +3 and is stored at the 10th address as 7 + 3 = 10. Is selected as the frequency used by the 65th frequency Frq (65). In the same way, when the offset of each wireless terminal is determined, the corresponding random address is generated and the frequency value stored in the random address is used as the frequency of the corresponding cycle. At this time, the offset adder 806 adds the offset value allocated every frame to the output random address so that the value can be used as the final frequency table address. The lower portion of the figure shows the frequency usage history 43 of each radio terminal in the t-th cycle. The group master uses the frequency stored at address '7' with offset '0', the wireless terminal 1 with offset '3' uses the frequency stored at address '10', and the radio with offset '6'. Terminal 2 uses the frequency stored in address '13', and wireless terminal 3 with offset '10' uses the frequency stored in address '1' so that all wireless terminals use different frequencies at the same time. There is no frequency conflict between users.

In the same way, the frequency usage history 44 used in the (t + 1) th cycle uses the frequencies stored in the frequency table addresses 3, 6, 9, and 13, respectively. Although frequency hopping randomly by cycle, wireless terminals always use different frequencies to enable orthogonal hopping without frequency collision. Other parts of the prior art are described in detail in the publication, and further description thereof will be omitted.

On the other hand, in the prior art, since the RF module of each wireless terminal is responsible for voice communication, the operation of frequency sounding, that is, selecting an optimal frequency and creating a frequency table is, for example, a state in which the power of the master wireless terminal is turned off. In this case, the operation is limited only in the case of being turned on (positive sounding) or when the master wireless terminal is not currently performing voice communication (sleeping sounding).

However, according to the prior art as described above, since the frequency table is not created at every jump, heterogeneous devices using the same frequency band, that is, the ISM band, for example, Access Point (AP), Bluetooth or Zigbee (Zigbee). Wireless Terminals When heterogeneous devices such as wireless LAN terminals or microwave ovens enter the operating area, radio interference occurs between these heterogeneous devices, such as delay, distortion or disconnection of voice signals. There was a problem that caused a serious deterioration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and is a master wireless radio channel searcher dedicated to real-time optimal frequency searching in a short-range wireless voice communication system having an interference avoidance function composed of a single master and one or more slave radio terminals. It is an object of the present invention to provide a short-range wireless voice communication system having an interference avoidance function that enables a jump to a frequency (channel) without interference from heterogeneous devices as well as homogeneous devices by operating separately from the terminal.

In the short-range wireless voice communication system having the interference avoiding function of the present invention for achieving the above object, in the short-range wireless voice communication system performing wireless communication between two or more wireless terminals in the short range, each hopping cycle A clean channel searcher which scans all available frequency channels for each extraction and extracts a plurality of clean channels; Constructing a frequency table based on clean channel information output from the clean channel searcher, outputting a random value for selecting a frequency channel to jump from the frequency table, and determining a frequency channel to which the user hops based on the random value. It comprises a single master radio terminal and at least one slave radio terminal for determining a frequency channel to which it hops based on the random value output from the master radio terminal in the same frequency table as the master radio terminal. It is characterized by.

In the above configuration, the slave wireless terminal may receive the clean channel information from the master wireless terminal or the clean channel searcher to build the frequency table.

Further, a unique offset value is assigned to the master radio terminal and each slave radio terminal, and the master radio terminal and each slave radio terminal are generated by adding the offset value unique to the random value to the master radio terminal and each slave radio terminal. The frequency channel matched to the address value of the frequency table may be determined as the frequency channel to which it hops.

According to the short-range wireless voice communication system having the interference avoiding function of the present invention, a separate clean channel searcher is used to search for clean channels that are not occupied or interfered by homogeneous or heterogeneous devices existing in the short range area at each hop cycle, and are mastered therefrom. And by allowing the slave wireless terminal to determine the frequency to use for each hopping cycle, each wireless terminal can transmit its voice signal through a frequency channel that is not occupied or interfered by the heterogeneous device as well as the homogeneous device, thereby delaying more. It enables high quality voice communication without distortion or disconnection.

Hereinafter, a short range wireless voice communication system having an interference avoidance function will be described in detail with reference to the accompanying drawings of the present invention.

4A to 4C are diagrams illustrating various applications of a short range wireless voice communication system having an interference avoiding function of the present invention, and dotted lines indicate unidirectional communication and solid lines indicate bidirectional communication. First, in the application example shown in FIG. 4A, a single master wireless terminal M and a single slave wireless terminal S exist in an arbitrary short-range region, and the blue channel searcher C is connected to the master wireless terminal M. Connected applications are shown. In this case, both the master (M) and slave (S) radio terminals may operate as the master (M) or slave (S) radio terminals, respectively, according to a given task in the state of being configured in the same configuration (hereinafter, Fig. 4 (b). ) And (c) are the same).

Each master (M) and slave (S) wireless terminal performs voice communication by hopping at its assigned frequency from the frequency table updated at every hopping cycle of voice communication. Frequency interference of the source can be prevented. Furthermore, frequency hopping is performed by a frequency table established by receiving a plurality of clean channels that are not currently occupied, that is, occupied or not used, by the clean channel searcher C, thereby preventing even frequency interference between heterogeneous devices. Will be. As described above, each master (M) or slave (S) wireless terminal transmits a voice signal using a frequency assigned to it, and the receiving wireless terminal checks the corresponding frequency on the frequency table and checks the corresponding frequency. By filtering only the signal, the corresponding voice signal can be received.

 Next, first, the application shown in FIG. 4B includes a single master (M) radio terminal and two or more slave radio terminals (S) in an arbitrary short range area, and a green channel searcher ( C) shows an example of the connected application, the master (M) radio terminal can transmit the same voice signal in one direction to all other slave (S) terminal using the frequency assigned to it. In the application shown in FIG. 4B, bidirectional communication may be performed between any slave S radio terminals (or between the slave and the master radio terminals), in which case each slave S radio terminal is connected to its own. By using the assigned frequency, it is possible to transmit its own voice signal to the slave (S) wireless terminal of the other party.

Next, in the application shown in FIG. 4C, a single master (M) radio terminal and two or more slave (S) radio terminals exist in an arbitrary short-range area, and the listening channel searcher (C) is located in the master (M) radio terminal. ) Shows an example of an application to which a) is connected. In this application, unlike in the example of FIG. 4B, an arbitrary slave S wireless terminal may transmit a voice signal in one direction to another slave S wireless terminal. 4A to 4C may correspond to the application examples of FIGS. 1 to 3 of the prior art publications, as well as the application examples corresponding to FIGS. 4 and 5 of the prior art publications. It will be possible.

5 is an internal functional block diagram of a master wireless terminal and a clean channel searcher in a short range wireless voice communication system having an interference avoiding function of the present invention, except that the master wireless terminal is connected to the clean channel searcher by wire / wireless. And the same configuration as the slave wireless terminal. As shown in FIG. 5, the master wireless terminal M of the short range wireless voice communication system having the interference avoiding function of the present invention is the RF module 100, the modem 110, the control unit 120, and the mode as in the prior art. The conversion unit 130 may include an audio codec 140, a speaker 150, and a microphone 160.

In the above-described configuration, the RF module 100 receives a high frequency signal transmitted from another wireless terminal at a predetermined frequency, and transmits a high frequency signal of an audio source provided by a user voice or an audio device connected to the wireless terminal to each hop cycle. Transmitting through a differently allocated frequency channel, an orthogonal hopping scheme is applied to prevent a frequency collision. Next, the modem 110 is composed of a reception area 112 and a transmission area 14, where the reception area 112 and the transmission area 114 is a mode of the wireless terminal, that is, whether it is a unidirectional mode or a bidirectional mode. Therefore, data is transmitted and received in different time slots.

The reception area 112 performs a process of demodulating the received high frequency signal and converting the received RF signal into a baseband signal when the RF module 100 selectively receives an audio sound source or a user voice transmitted by another wireless terminal. Meanwhile, the transmission area 114 performs a process of modulating a user's voice into a high frequency signal.

The controller 120 performs the function of controlling the frequency selection process of the RF module 100 and the overall modulation and demodulation of the modem, and performs the frequency hopping function described later. The mode switching unit 130 corresponds to a user interface. Preferably, the mode switching unit 130 is connected to a button for mode switching on the wireless terminal, that is, a button for switching between a unidirectional mode and a bidirectional mode, to the controller 120. Send the user mode switching signal. Accordingly, the controller 120 controls the RF module 100 to selectively receive a different frequency signal than before.

Finally, the audio codec 140 is connected to the speaker 150 and the microphone 160 to decode the audio source or the user voice demodulated into the baseband signal according to a preset algorithm. The decoded data is the speaker 150. Is played through. The audio codec 140 also functions to encode an audio sound source provided by an audio device connected to a user voice or a wireless terminal and transmit the encoded audio sound source to the modem 110.

Next, the clean channel searcher (C) scans the entire channel that can be used by each radio terminal (M or S) largely for each hopping cycle, so that the radio wave strength information on the corresponding channel, for example, RSSI (Received Signal Strength Indication) ) To analyze the radio wave intensity information outputted from the full channel scan unit 200 and the full channel scan unit 200 to output a predetermined number, for example, as many as 16 clean channels, that is, to other devices The clean channel extractor 210 and the clean channel extractor 210 extracting the channel occupied or uninterrupted by the clean channel extractor 210 are wired or wirelessly transmitted to the controller 120 of the master wireless terminal M. It may be made to include a communication unit 220.

In the above-described configuration, the clean channel extractor 210 may extract about 16 channels in total in the order of the smallest radio wave strength by analyzing the radio wave intensity information received from the all channel scan unit 200.

6 is a functional block diagram illustrating a frequency hopping process in the master and slave radio terminals of the short range wireless voice communication system having the interference avoiding function of the present invention. As shown in FIG. 6, the master radio terminal M of the present invention clean channel information, that is, magnetic (M) or slave (S) from the clean channel searcher (C) wired or wirelessly every hop cycle as described above. ) The radio terminal receives a plurality of hopping frequency information that can be used for transmitting a voice signal, constructs a frequency table 320 and simultaneously transfers the same to the slave radio terminal S by transmitting the same to each slave radio terminal S. The frequency table 320 will be shared. In this state, the master wireless terminal (M) generates a random (number) value according to the algorithm determined through the hopping sequence generator (300) and transfers it to the self (M) and the other slave wireless terminal (S). The generated random value is then added to the offset value given by the offset adder 310 of the self M and each slave radio terminal S so as not to overlap each other, and is output as an address value of the frequency table 320. . Then, the master (M) and slave (S) radio terminals then hop to a frequency matching the corresponding address value of the frequency table 320 and transmit their voice signal during the corresponding cycle.

Meanwhile, the master radio terminal transmits the clean channel information and the random value generated by the hop sequence generator to the slave radio terminal during the synchronization control period (see reference numeral 31 of FIG. 10 of the related art). By doing so, synchronization with the slave radio terminal can be maintained.

The short-range wireless voice communication system having the interference avoiding function of the present invention is not limited to the above-described embodiments, and various modifications can be made within the range allowed by the technical idea of the present invention. For example, unlike the above-described embodiment, each slave wireless terminal may receive clean channel information directly from the clean channel searcher simultaneously with the master wireless terminal without receiving the clean channel information from the master wireless terminal. The clean channel detector may be formed integrally with the master wireless terminal, that is, one body.

1 is a block diagram of a wireless terminal according to the prior art,

2 is a block diagram of an RF module in FIG.

3 illustrates a frequency table for orthogonal hopping in the prior art;

4A, 4B and 4C illustrate various applications of a short range wireless voice communication system having an interference avoidance function according to the present invention;

5 is an internal functional block diagram of each wireless terminal and a clean channel searcher in a short-range wireless voice communication system having an interference avoiding function of the present invention;

6 is a functional block diagram illustrating a frequency hopping process in the master and slave radio terminals of the short range wireless voice communication system having the interference avoiding function of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100: RF module, 110: modem,

112: reception area, 114: transmission area,

120: control unit, 130: mode switching unit,

140: audio codec, 150: speaker,

160: microphone, 200: all-channel scanning unit,

210: clean channel extraction unit, 220: communication unit,

300: jump sequence generator, 310: offset adder,

320: frequency table, M: master wireless terminal,

S: Slave wireless terminal, C: Clean channel searcher

Claims (5)

In a short range wireless voice communication system for wirelessly performing voice communication between two or more wireless terminals in a short range area, A clean channel searcher which scans all available frequency channels for each hopping cycle and extracts and outputs a plurality of clean channels; Constructing a frequency table based on clean channel information output from the clean channel searcher, outputting a random value for selecting a frequency channel to jump from the frequency table, and determining a frequency channel to which the user hops based on the random value. A single master wireless terminal and And at least one slave radio terminal configured to determine a frequency channel to which it should hop based on the random value output from the master radio terminal in the same frequency table as the master radio terminal. Short-range wireless voice communication system having a function. The short range wireless voice communication system of claim 1, wherein the slave wireless terminal receives the clean channel information from the master wireless terminal to construct the frequency table. The short range wireless voice communication system according to claim 1, wherein the slave wireless terminal receives the clean channel information directly from the clean channel searcher and constructs the frequency table. 4. The interference according to any one of claims 1 to 3, wherein the clean channel searcher extracts a plurality of clean channels in order of low propagation strength of each frequency channel obtained by scanning all available frequency channels. Short-range wireless voice communication system having an evasion function. The method of claim 4, wherein the master radio terminal and each of the slave radio terminal is assigned a unique offset value, The master radio terminal and each slave radio terminal determine the frequency channel matched to the address value of the frequency table generated by adding the offset value unique to the random terminal as the frequency channel to which the master hops. Short-range wireless voice communication system having an interference avoiding function, characterized in that.

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