KR101475006B1 - Wireless group communication system, device for wireless group communication system, and method for wireless group communication - Google Patents

Abstract

The wireless group communication system includes a master device and slave devices each performing wireless group communication with the master device in synchronization with a beacon signal transmitted through each of the beacon time slots from the master device. Each of the master device and the slave devices performs group call communication in a frequency band of 2.4 GHz or 900 MHz using a super frame including a beacon period including a beacon time slot, a control signal period, and a data period.

Description

Technical Field [0001] The present invention relates to a wireless group communication system, a wireless group communication system, and a wireless group communication method for a wireless group communication system,

The present invention relates to a communication module technology for multi-party communication (multi-party voice transmission / reception technology), and more particularly to a wireless group communication system capable of using 2.4 GHz and 900 MHz frequencies, And a wireless group communication method.

Recently, various Bluetooth or Zigbee type short range wireless communication devices have been provided. However, the short-range wireless communication apparatus of the above-described method may not be suitable for a multi-party conference, a sightseeing guide, or a simultaneous interpretation because it mainly uses data communication in a 1: 1 manner. Conventionally, a transceiver for multi-party conferencing has been provided. In such a transceiver system, a plurality of persons can hear the contents of a call at the same time, but it is possible to communicate only in one direction, so that a push-to-talk (PTT) Can be. An example of a short-range wireless communication system that solves the above problem is disclosed in Korean Patent Laid-Open No. 10-2011-0028103.

On the other hand, many wireless devices such as the above-described short-range wireless communication devices currently use 2.4 GHz. Typically, there are wireless LAN (WiFi), Bluetooth, and Zigbee. As a result, 2.4GHz radio resources are saturated and interference between the devices becomes a problem in many situations. Typically, there are a lot of wireless LANs, and when using other devices such as Bluetooth and ZigBee in the wireless LAN section, the wireless performance may remarkably deteriorate.

900MHz is assigned to low rate (data rate) and low bandwidth in wireless standard compared to 2.4GHz and is currently used mainly in analog communication. However, 900MHz has better radio characteristics than 2.4GHz, and currently used devices are limited. Therefore, 900MHz is a frequency band that has good radio characteristics because there is no collision between 900MHz devices.

SUMMARY OF THE INVENTION The object of the present invention is to monitor 2.4GHz and 900MHz of each frequency band environment in a given environment and change 2.4GHz and 900MHz in consideration of the monitored frequency environment A wireless group communication system for a wireless group communication system, and a wireless group communication method.

According to an aspect of the present invention, there is provided a wireless group communication system including: a master device; And a slave device performing a wireless group communication with the master device in synchronization with a beacon signal transmitted through each of the beacon time slots from the master device, wherein each of the master device and the slave devices May perform group talk communication in a frequency band of 2.4 GHz or 900 MHz using a superframe including a beacon period, a control signal period, and a data period including the beacon time slots.

The master device calculates a Received Signal Strength Indication value for a wireless communication signal of the 2.4 GHz frequency band received from each of the slave devices, A superframe including a beacon signal included in the beacon interval and a frequency change signal included in the control signal interval is transmitted to each of the slave devices, so that each of the master device and the slave devices The frequency band used can be changed to 900MHz. The master device may transmit a super frame including the frequency change signal five times.

Wherein the master device calculates a link quality indicator value for a radio communication signal of the 2.4 GHz frequency band received from each of the slave devices, A superframe including a beacon signal included in the beacon period and a frequency change signal included in the control signal interval is transmitted to each of the slave devices when the master device and the slave devices are used, Can be changed to 900 MHz. The master device may transmit a super frame including the frequency change signal five times.

Wherein the master device comprises: a 2.4 GHz transceiver for transmitting or receiving a radio communication signal in the frequency band of 2.4 GHz; A 900 MHz transceiver for transmitting or receiving a radio communication signal in the 900 MHz frequency band; An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And a micro controller unit (MCU) unit for controlling operations of the 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the audio codec unit.

Each of the slave devices includes a 2.4 GHz transceiver for transmitting or receiving a radio communication signal in the frequency band of 2.4 GHz; A 900 MHz transceiver for transmitting or receiving a radio communication signal in the 900 MHz frequency band; An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And an MCU unit for controlling operations of the 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the audio codec unit.

According to an aspect of the present invention, there is provided a wireless group communication device as a master device for a wireless group communication system, comprising: a wireless communication module for converting a wireless communication signal in a 2.4 GHz frequency band into a beacon period, a control signal period, A 2.4 GHz transceiver for transmitting or receiving via a superframe included; A 900 MHz transceiver for transmitting or receiving a wireless communication signal in a 900 MHz frequency band through a super frame including a beacon period, a control signal period, and a data period; An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And an MCU unit for controlling operations of the 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the audio codec unit. The MCU unit may include the 2.4 GHz transceiver unit or the 900 MHz transceiver unit in the superframe received through the 2.4 GHz transceiver unit or the 900 MHz transceiver unit. Receiving unit and the 900-MHz transceiver based on the received wireless communication signal.

The MCU unit calculates a received signal strength (RSSI) value for a 2.4-GHz frequency band wireless communication signal received from each of the slave devices via the 2.4 GHz transceiver unit, The beacon signal included in the beacon interval and the frequency change signal included in the control signal interval are transmitted to the slave devices through the 2.4 GHz transceiver when the received superframe is greater than the intensity value, The master device and the slave devices in synchronization with the beacon signal can change the frequency band to 900 MHz.

Wherein the MCU unit calculates a link quality index (LQI) value for the 2.4GHz frequency band wireless communication signal received from each of the slave devices through the 2.4GHz transceiver unit, And transmitting a superframe including the beacon signal included in the beacon period and the frequency change signal included in the control signal interval to each of the slave devices through the 2.4 GHz transceiver when it is smaller than the exponent value, The master device and the slave devices in synchronization with the beacon signal can change the frequency band to 900 MHz.

According to another aspect of the present invention, there is provided a wireless group communication method comprising the steps of: (a) transmitting a beacon signal synchronizing each of the slave devices with the master device and slave devices; Performing wireless audio communication in a 2.4 GHz frequency band using a super frame including a beacon period including a beacon time slot, a control signal period, and a data period; (b) calculating, by the master device, a received signal strength (RSSI) value for a wireless communication signal of a 2.4 GHz frequency band received from each of the slave devices; And (c) if the received signal strength value calculated in step (b) is greater than a reference received signal strength value, the master device transmits a beacon signal included in the beacon period and a frequency change signal included in the control signal period And changing the frequency band of use of each of the master device and the slave devices to 900 MHz by transmitting the superframe including the superframe to each of the slave devices.

According to another aspect of the present invention, there is provided a wireless group communication method comprising the steps of: (a) transmitting a beacon signal for synchronizing each of the slave devices with the master device and slave devices; Performing a wireless audio communication in a 2.4 GHz frequency band using a super frame including a beacon period including a beacon time slot, a control signal period, and a data period; (b) calculating, by the master device, a link quality index (LQI) value for a wireless communication signal in the 2.4 GHz frequency band received from each of the slave devices; And (c) when the link quality index value calculated in step (b) is smaller than a reference link quality index value, the master device transmits a beacon signal included in the beacon period and a frequency change signal included in the control signal interval And changing the frequency band of use of each of the master device and the slave devices to 900 MHz by transmitting the superframe including the superframe to each of the slave devices.

The wireless group communication system, the wireless group communication apparatus and the wireless group communication method for the wireless group communication system according to the present invention can selectively operate wireless communication signals in the 2.4 GHz or 900 MHz frequency band, Performance can be improved.

Also, since the present invention can selectively operate a wireless communication signal in the 2.4 GHz or 900 MHz frequency band, it is possible to provide a clean sound quality and a stable wireless communication signal without interfering with wireless communication in an adjacent area.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the drawings used in the detailed description of the present invention, a brief description of each drawing is provided.
1 is a diagram illustrating a wireless group communication system 100 according to an embodiment of the present invention.
2 is a diagram for explaining an embodiment of the master device 105 or the slave devices 110, 115, or 120 shown in FIG.
FIG. 3 is a view for explaining an example of a superframe structure used for signal transmission in the wireless transceivers 105, 110, 115, and 120 shown in FIG.
FIG. 4 is a diagram showing a data section of the super frame shown in FIG.
5 is a view for explaining a scan frame used in a slave device for receiving a beacon signal of the master device 105 shown in FIG.
FIG. 6 is a diagram for explaining a process (method) in which the slave device of FIG. 1 participates in group communication using superframe information of a beacon signal received from a master device.
FIG. 7 is a diagram for explaining a frequency conversion method according to an embodiment of the present invention applied to the wireless group communication system 100 shown in FIG.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, and the objects attained by the practice of the invention, reference should be made to the accompanying drawings, which illustrate embodiments of the invention, and to the description in the accompanying drawings.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Like reference numerals in the drawings denote like elements.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having", etc., are used to specify that a feature, a number, a step, an operation, an element, a component, or a combination thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and, unless expressly defined herein, are to be construed as either ideal or overly formal Do not.

The present invention relates to a superframe structure for monitoring each frequency band (2.4 Hz, 900 MHz), a frequency band monitoring method, a method for changing a frequency band using a control signal included in a superframe structure, .

1 is a diagram (block diagram) illustrating a wireless group communication system 100 according to an embodiment of the present invention.

Referring to FIG. 1, a wireless group communication system 100 includes a master device 105 and slave devices 110, 115, and 120. Each of the master device 105 or the slave devices 110, 115, and 120 may be a group communication device in which a plurality of users can perform group communication.

The wireless group communication system 100 basically can perform a communication method of a master / slave structure (master and slave structure). The master device 105 transmits a Beacon signal as a reference for communication and each of the slave devices 110, 115 and 120 synchronizes with a beacon signal transmitted from the master device 105 to communicate with each other .

Master device 105 is a device for managing a network of a group communication system and transmits a beacon (beacon signal) serving as a reference for group communication so that other wireless devices (slave devices 110, 115, and 120) To be synchronized. The master device 105 manages network resources (superframe resources), and allocates or allocates network resources to wireless devices. The network resource includes a beacon time slot, a frequency offset and a channel, a frequency offset is an index of a frequency to be used for group communication, and a channel is a time slot of a data interval to be used for group communication. Also, the master device 105 monitors the beacon of the other wireless device, grasps the network structure of the group communication system, and transmits network information to other wireless devices. Only one master device 105 in the group communication system may be formed, and a plurality of master devices 105 may be formed according to the situation.

Each of the slave devices 110, 115 and 120 may be directly connected to the master device 105 or via another slave device and may be connected to the master device 105 from a beacon or other slave device Synchronizes with the beacon being transmitted.

Each of the slave devices 110, 115, and 120 may be a relay transmission / reception device, a relay only device, and a reception-only device.

The relay transmission / reception device is a device that performs a relay function in addition to voice transmission / reception for group call, and the relay dedicated device is a device that performs a relay function without participating in a group call. The relay device such as the relay transceiver and the relay exclusive device receives the beacon and is synchronized with the master device 105 or other relay device. The beacon time slot is allocated from the master device 105, Allow the device to be synchronized. The relay device transmits the information of the connected wireless device directly or through at least one other relay device to the master device 105 so that the master device 105 can grasp the network status. The relay apparatus also receives network information from the master apparatus 105 directly or through another relay apparatus. The number of such repeaters may be determined by the transmission rate of a radio frequency (RF) transceiver used in the wireless device. The reception-only device is a device that does not participate in the group call but receives only the voice of the group call, and receives the voice of the group call without being allocated the network resource.

The master device 105, the relay transceiver and the relay dedicated device each transmit a beacon in a slot assigned to itself in a beacon period and receive a beacon from another wireless device in another slot in the beacon period. A receive-only device does not transmit a beacon but receives a beacon from another wireless device in a beacon period. The master device 105 and the relay transceiver transmit and receive the group call via the channel assigned to them, respectively, and the relay device relays the group call from the other wireless device to another wireless device. A receive-only device does not send a group call, but receives a group call from another wireless device.

Each of the master device 105 and the slave devices 110, 115 and 120 can be operated with 2.4 GHz and 900 MHz transceivers as shown in FIG. The wireless group communication system 100 using 2.4 GHz and 900 MHz can talk (talk) with 3 to 4 people at the same time. 900MHz has better radio characteristics than 2.4GHz, and currently used devices are limited. Therefore, 900MHz is a frequency band that has good radio characteristics because there is no collision between 900MHz devices.

2 is a diagram for explaining an embodiment of the master device 105 or the slave devices 110, 115, or 120 shown in FIG.

2, master device 105 or slave device 110, 115, or 120 is a wireless transceiver device (wireless device) and includes a 2.4 GHz antenna portion 202, a 900 MHz antenna portion 204, a 2.4 GHz A microcontroller unit (MCU) unit 215, and an audio CODEC unit 220. The transmission / reception unit 205, the 900 MHz transmission / reception unit 210,

The 2.4 GHz transceiver unit 205 may transmit or receive a wireless communication signal including an audio signal (user's voice signal) of 2.4 GHz frequency band received through the 2.4 GHz antenna unit 202. The 2.4 GHz transceiver unit 205 may include an RF module (radio frequency module) and a modem (MODEM). The RF module receives a signal received from another wireless transmitting / receiving device wirelessly through the 2.4 GHz antenna unit 202, and the modem can demodulate the received signal into a baseband signal.

The 900 MHz transceiver 210 may transmit or receive a wireless communication signal including an audio signal of 900 MHz frequency band received through the 900 MHz antenna unit 204. [ The 900 MHz transceiver 210 may include an RF module and a modem. The RF module receives a signal received from another wireless transmitting / receiving device wirelessly through the 900 MHz antenna unit 204, and the modem can demodulate the received signal into a baseband signal.

The audio codec unit 220 decodes an encoded digital signal output from the 2.4 GHz transceiver unit 205 or the 900 MHz transceiver unit 210 and outputs the decoded digital signal as an analog signal. The output analog signal may be output through a speaker (not shown) included in the WTRU. The audio codec unit 220 converts a voice input through a microphone (not shown) of the wireless transceiver into a digital signal through the audio codec unit 220 when transmitting an audio signal (voice). The converted digital signal is modulated by the 2.4 GHz transceiver 205 or the modem of the 900 MHz transceiver 210 and is upconverted to the high frequency through the RF module of the 2.4 GHz transceiver 205 or the 900 MHz transceiver 210 upconverted to be wirelessly transmitted to another wireless transmitting / receiving device.

The MCU unit 215 is a dedicated processor for controlling the wireless transceiver and includes components (2.4 GHz transceiver unit 205, 900 MHz transceiver unit 210, and audio codec unit 220) included in the wireless transceiver Can be controlled.

3 is a diagram illustrating a superframe structure for monitoring each frequency band according to an embodiment of the present invention. 3 is a view for explaining an example of a superframe structure used for signal transmission in the wireless transceivers 105, 110, 115, and 120 shown in FIG.

Referring to FIG. 3 and FIG. 1, scheduling is performed in a super frame unit using a time division multiple access (TDMA) scheme. That is, the master device 105 can schedule resources on a super frame basis using the time division multiple access scheme.

The super frame may include a beacon period, a control signal period, and a data period in the time domain. The beacon period is a period during which the master device 105 and the slave devices 110, 115, and 120 transmit beacon signals. The wireless device receives a beacon from another wireless device during a period in which the wireless device does not transmit the beacon during the beacon period. The beacon period includes a plurality of time slots, and the number of time slots may be determined by the transmission rate of the RF transceiver, that is, the number of relay apparatuses. The master device 105 manages the resources of the time slot of the beacon period. All of the slave devices 110, 115, or 120 receive the beacon transmitted by the master device 105 and are synchronized with the master device 105. When the slave device 110, 115 or 120 requests beacon assignment to the master device 105 after synchronization with the master device 105, the master device 105 allocates the remaining time slot to the slave device. When the master device 105 is disconnected from the slave devices 110, 115, or 120, the master device 105 recovers time slots assigned to the slave devices. Accordingly, different time slots may be allocated to the plurality of slave devices 110, 115, and 120 in the beacon period.

The control signal section is a section for transmitting / receiving a control signal, and includes a plurality of time slots. The control signal may include call connection request and response, call connection change request and response, resource allocation request and response, and the like. The number of time slots in the control signal interval may be determined according to the transmission rate (i.e., the number of slave devices (repeaters)) of a radio frequency (RF) transceiver used in the wireless transceiver, 1 < / RTI > This is the same as the number of channels of the data section shown in FIG.

FIG. 4 is a diagram showing a data section of the super frame shown in FIG.

Referring to FIG. 4, the data interval includes a plurality of channels (channel 0 to channel N) (data time slots) for transmitting and receiving voice data. The number of channels in the data interval may be determined according to the transmission rate of the RF transceiver, that is, the number of repeaters, and may be the same as the number of time slots in the control signal interval. As shown in FIG. 4, each channel of the data interval may be a bi-directional channel, that is, a transmission channel and a reception channel.

As shown in FIG. 5, slave devices (110, 115, or 120 in FIG. 1) receive a beacon using a scan frame. The scan frame is allocated twice as much as the super frame structure, and the scan frame structure is repeatedly performed while changing the frequency until the beacon is received.

5 is a view for explaining a scan frame used in a slave device for receiving a beacon signal of the master device 105 shown in FIG. That is, FIG. 5 shows a synchronization method in a slave device which is a wireless device of a wireless group communication system according to an embodiment of the present invention.

5 and 1, a slave device 110, 115, or 120 that is not synchronized with the master device 105 scans a beacon using a scan frame instead of a super frame. That is, the slave devices 110, 115, or 120 scan the beacon by repeating the scan frame while changing the scan frequency until the beacon is received. The slave device selects a wireless device that has transmitted the beacon with the best reception state among the received beacons while scanning, and synchronizes with the wireless device. At this time, the slave device can determine the reception state based on at least one of the received signal strength indication (RSSI) value and the reception error rate. That is, the slave device can select the wireless device that transmitted the beacon with the largest RSSI and no error. Whereby the slave device can be connected to another wireless device, i. E. A master device or a relay device, in the group communication system.

As shown in FIG. 6, slave devices (110, 115, and 120 in FIG. 1), which are group communication devices, receive a beacon of the master device (105 in FIG. The slave device receiving the beacon changes the scheduling to the super frame rescue using the super frame information of the received beacon. Then, the slave device participates in the wireless group communication by attempting resource allocation and call connection.

FIG. 6 is a diagram for explaining a process (method) in which the slave device of FIG. 1 participates in group communication using superframe information of a beacon signal received from a master device. That is, FIG. 6 shows a superframe structure after synchronization.

Referring to FIG. 6 and FIG. 1, the slave devices 110, 115, and 120 change the scheduling from a scan frame to a superframe and allocate resources to the synchronized wireless device through a control signal interval It attempts to connect the call through the requested and allocated resources.

A group communication method (call connection method) and a resource allocation method in a wireless group communication system according to an embodiment of the present invention will be described with reference to FIG.

After the wireless device synchronizes to another wireless device, it requests a resource allocation to the wireless device. At this time, the resource requested by the wireless device may be at least one of a beacon time slot, a call channel, and a frequency offset.

The wireless device, in particular the relay device, first receives and synchronizes the beacon from the master device 105. After synchronization, the wireless device requests beacon allocation to the synchronized device through the control signal interval of the superframe. If the synchronized device is the master device, the master device allocates a beacon time slot to the wireless device if there are remaining beacon time slots. If the device synchronized by the wireless device is not a master device but a relay device, the relay device relays the beacon allocation request of the wireless device to the master device or transmits the beacon allocation request to the master device. As such, the wireless device requests beacon assignment directly to the master device or requests beacon assignment to the master device via at least one other relay device.

The master device 105 allocates the remaining beacon time slot to the corresponding wireless device in response to the beacon allocation request, and sets the wireless device as a non-relayable wireless device if there is no remaining beacon time slot. A wireless device that can not relay can perform other functions normally except for the relay function and request the beacon allocation again when the connection of the group communication system is changed.

Meanwhile, the wireless devices participating in the group communication request the frequency offset and the channel allocation to be used for the group communication to the synchronized device through the control signal interval of the superframe after synchronization. Even in this case, the wireless device can directly request allocation to the master device or request allocation to the master device through at least one other relay device. The master device 105 assigns a frequency offset and a channel to the wireless device in response to the allocation request.

The wireless device participating in the group call requests a call connection to the connected wireless device, that is, the relay device or the master device. The wireless device receiving the call connection request provides network information such as channel and frequency offset information of itself and other wireless devices connected thereto with the wireless device requesting the call connection, and the wireless device participates in the group call based on the network information.

When a reception state of a device connected to the wireless device is deteriorated due to a movement of the wireless device during a group call, the wireless device recognizing the wireless device attempts to change the connection. The wireless device may determine the reception state based on the RSSI value of the beacon and / or data and / or the reception error rate or the like. For example, if the RSSI value falls below the reference RSSI value and the receive error rate increases, the wireless device may change the call connection. The wireless device may determine that the wireless device that transmits the beacon with the highest RSSI and the lowest reception error rate is the wireless device to which the wireless device is connected.

Referring to FIG. 1, a network management method (network information sharing method) in a group communication system according to an embodiment of the present invention will be described as follows.

The master device 105 periodically provides network information to the slave devices 110, 115, and 120. When the slave device is a relay device, the slave device transmits network information to another slave device connected to the slave device. In this way, all the slave devices of the group communication system can share the network information. The network information includes an ID of a wireless device connected to each link by an identifier (ID) of the wireless device.

In order to manage the network, the master device 105 stores a network information table including information of wireless devices allocated for each beacon time slot. The information of the wireless device includes a device ID, a frequency offset allocated to the wireless device, and link status information of the wireless device. Here, the link state information includes the ID of the wireless device forming the link and the link quality indicator (LQI) value of the link.

Each of the slave devices 110, 115, and 120 receives the network information and the beacon and generates a link table having link information for a wireless device connectable to the slave devices. Each of the slave devices 110, 115, and 120 generates network information including the used frequency offset and link information, and transmits the generated network information to the master device 105. At this time, the link information may include link-specific connection information (i.e., the ID of the connected wireless device) and LQI value for each link.

A slave device not directly connected to the master device 105 transmits its network information via another slave device having a relay function, that is, a relay device.

Through such network management, the wireless device periodically updates the RSSI value and the reception error rate of the beacon when receiving the network information and the beacon, and the wireless device transmits the beacon with the good RSSI and the low reception error rate Priority is assigned. According to another embodiment, the wireless device determines a wireless device to which a new link will be connected when the current link condition is degraded based on network information and beacons. At this time, the wireless device can determine a new wireless device so that no loop is generated between the plurality of wireless devices. According to another embodiment, the wireless device requests network information update when the information related to the received network information differs from the current status. According to another embodiment, the wireless device informs the wireless device connected to it of the link disconnection when the connection of the link, which can be directly connected with the master device or via the relay device, is lost and the link can not be recovered, Lt; / RTI >

A wireless device according to an embodiment of the present invention will now be described.

The wireless device includes a control unit and a transmission / reception unit. The control unit may set the operation of the wireless device to a mode (master mode) operating as a master device, a mode (relay mode) operating as a relay device, a mode operating as a receive-only device (receive mode), and the like. At this time, the relay mode may include a mode (relay transmission / reception mode) operating as a relay transmission / reception device and a mode (relay dedicated mode) operating as a relay dedicated device.

The control unit determines the wireless device having the best reception state based on the beacon scanned when the relay mode is in the relay mode, and manages the network information, the link table, and the like. The transmitting and receiving unit requests allocation of a beacon time slot to the synchronized wireless device and transmits a beacon through the allocated beacon time slot when the beacon time slot is allocated from the master device. In addition, the transmitting and receiving unit requests the frequency offset and the channel allocation to the synchronized wireless device, and tries the group call through the frequency offset and the channel allocated when the frequency offset and the channel are allocated from the master device.

As described above, according to the embodiment of the present invention, each wireless device can be connected to the master device through the relay device even when the wireless device is far from the master device, and the beacon time slot, frequency offset, data time slot, You can freely participate in the group call.

A method of detecting a frequency congestion according to an embodiment of the present invention will now be described.

The frequency congestion detection method may also be referred to as a frequency band monitoring method.

A method of detecting 2.4 GHz or 900 MHz congestion may be a channel scanning method of the master device and a method of using a communication error during communication.

The channel scanning method of the master device receives each frequency band before communication for each frequency and grasps (detects) the congestion degree of each frequency band using RSSI (Received Signal Strength Indication). It is possible to avoid the frequency band in which the RSSI value is low and select the high frequency band. When 2.4 GHz is scanned for the first time, 2.4 GHz is preferentially used, and when 2.4 GHz is congested in all bands, communication is performed using 900 MHz.

A method of using a communication error during communication informs each slave device to change the frequency by using a beacon signal when a continuous communication error occurs during communication. After broadcasting this five times (broadcasting, transmitting or broadcasting), the master device and the slave device change the frequency band. For this purpose, the master device records LQI (Link Quality Indicator, link quality index value or link quality information) for each frequency. The LQI can determine the class (the class of the LQI) using the RSSI and the frequency error rate (the reception error rate). For example, LQI = a x RSSI + b x CRC (0 < , a + b = 1). In the above equation, a and b are real numbers satisfying the above condition, and CRC is a cyclical redundancy check and may be a frequency error rate.

The frequency conversion method according to the embodiment of the present invention is described as follows.

The frequency conversion method may also be referred to as a method of changing a frequency band using a control signal.

7, the master device 105 monitors the LQI value and transmits a frequency change signal to each slave device 110, 115, or 120 using a beacon signal . If this is repeated five times, each device can change the frequency. That is, FIG. 7 is a view for explaining a frequency conversion method according to an embodiment of the present invention applied to the wireless group communication system 100 shown in FIG.

1 to 7, a wireless group communication system 100 according to an embodiment of the present invention will be described in detail as follows.

The wireless group communication system 100 is connected to the master device 105 and the master device 105 in synchronization with a beacon signal transmitted (transmitted or delivered) through each of the beacon time slots from the master device 105, And slave devices 110, 115, and 120 that respectively perform wireless group communication. Each of the master device 105 and the slave devices 110, 115 and 120 uses a super frame (super frame structure) including a beacon period, a control signal period and a data interval including beacon time slots To perform group talk communication (wireless group audio communication) in the frequency band of 2.4 (GHz) or 900 (MHz) (any one of 2.4 GHz and 900 MHz).

The master device 105 determines the reception signal intensity of the radio communication signal (beacon signal included in the radio signal having the 2.4 GHz frequency band) in the 2.4 GHz frequency band received from each of the slave devices 110, 115, A beacon signal included in the beacon interval and a frequency change included in the control signal interval when the calculated received signal strength value is greater than a reference received signal strength value, The frequency band used by each of the master device 105 and the slave devices 110, 115, and 120 is changed to 900 MHz by transmitting a super frame including a signal to each of the slave devices 110, . That is, the master device 105 detects the congestion degree of the 2.4 GHz frequency band by calculating the received signal strength value, and if it is determined that the frequency band of 2.4 GHz is relatively congested, Can be changed from 2.4 GHz to 900 MHz. The received signal strength (RSSI) value represents the strength of a silent signal received from the partner apparatus, for example, -100 (dBm) or higher and -0 (dBm) or lower. The reference received signal strength value may be a threshold value stored in the master device 105, for example, -50 (dBm). On the other hand, the master device 105 can transmit the superframe including the frequency change signal (the beacon signal and the frequency change signal) five times for more reliable use frequency change (change) operation.

In another embodiment of the present invention, the master device 105 transmits a radio communication signal in the 2.4 GHz frequency band (or a radio signal having a frequency band of 2.4 GHz) received from each of the slave devices 110, 115, The beacon signal included in the beacon interval when the calculated link quality index value is smaller than the reference link quality index value, and the beacon signal included in the beacon interval and the control signal < RTI ID = 0.0 &gt; 115 and 120 to each of the master device 105 and the slave devices 110, 115, and 120 by transmitting a super frame including the frequency change signal included in the interval to each of the slave devices 110, The frequency band can be changed to 900 MHz. That is, the master device 105 detects the congestion degree of the 2.4 GHz frequency band by obtaining the link quality index value, and if the 2.4 GHz frequency band is determined to be relatively congested, Can be changed from 2.4 GHz to 900 MHz. The LQI value indicates the quality of communication state between the master device 105 and the slave devices 110, 115, or 120. This value can be expressed as an integer between 0 and 255 as a bit error rate (BER) It may mean that the better the communication quality is. The LQI value may be expressed by a formula using an RSSI value (i.e., LQI = a x RSSI + b x CRC (0 <a <1, 0 <b <1, a + b = 1) . The reference link quality index (LQI) value may be, for example, 200 as a reference value stored in the master device 105. On the other hand, the master device 105 can transmit the superframe including the frequency change signal (the beacon signal and the frequency change signal) five times for more reliable frequency conversion (change) operation.

The master device 105 may include a 2.4 GHz transceiver 205, a 900 MHz transceiver 210, an audio codec 220 and an MCU 215 as shown in FIG. The 2.4 GHz transceiver unit 205 transmits or receives a radio communication signal in the 2.4 GHz frequency band and the 900 MHz transceiver unit 210 transmits or receives the radio communication signal in the 900 MHz frequency band. The audio codec unit 220 encodes the audio signal inputted through the microphone of the master device 105 and outputs the audio signal included in the wireless communication signal received through the 2.4 GHz transceiver 205 or the 900 MHz transceiver 210. [ / RTI &gt; The MCU unit 215 controls the operation of the 2.4 GHz transceiver unit 205, the operation of the 900 MHz transceiver unit 210, and the operation of the audio codec unit 220. The MCU unit 215 may also control the operation of changing the frequency band of the above-described wireless group communication system 100 from 2.4 GHz to 900 MHz.

Each of the slave devices 110, 115 and 120 may include a 2.4 GHz transceiver unit 205, a 900 MHz transceiver unit 210, an audio codec unit 220, and an MCU unit 215. The 2.4 GHz transceiver unit 205 transmits or receives a radio communication signal in the 2.4 GHz frequency band and the 900 MHz transceiver unit 210 transmits or receives the radio communication signal in the 900 MHz frequency band. The audio codec unit 220 encodes the audio signal input through the microphones of the slave devices 110, 115 or 120 and outputs the wireless communication signals received through the 2.4 GHz transceiver 205 or the 900 MHz transceiver 210. [ As shown in FIG. The MCU unit 215 controls the operation of the 2.4 GHz transceiver unit 205, the operation of the 900 MHz transceiver unit 210, and the operation of the audio codec unit 220.

1 to 7, a wireless group communication apparatus 105 which is a master apparatus for a wireless group communication system 100 according to an embodiment of the present invention will be described below.

The wireless group communication apparatus 105 as a master device included in the wireless group communication system 100 includes a 2.4 GHz transceiver unit 205, a 900 MHz transceiver unit 210, an audio codec unit 220, and an MCU unit 215 ).

The 2.4 GHz transceiver unit 205 transmits or receives a wireless communication signal in a 2.4 GHz frequency band through a super frame including a beacon period, a control signal period, and a data period. The 900 MHz transceiver 210 transmits or receives a radio communication signal in a 900 MHz frequency band through a super frame including a beacon period, a control signal period, and a data period. The audio codec unit 220 encodes the audio signal input through the microphone of the wireless group communication apparatus 105 and outputs the audio signal to the audio codec unit 220 included in the wireless communication signal received through the 2.4 GHz transceiver unit 205 or the 900 MHz transceiver unit 210 And decodes the audio signal. The MCU unit 215 controls the operation of the 2.4 GHz transceiver unit 205, the operation of the 900 MHz transceiver unit 210, and the operation of the audio codec unit 220. The MCU unit 215 receives either the 2.4 GHz transceiver unit 205 or the 900 MHz transceiver unit 210 based on the wireless communication signal received through the 2.4 GHz transceiver unit or the 900 MHz transceiver unit and included in the super frame (To be enabled).

The MCU unit 215 receives the radio communication signals in the 2.4 GHz frequency band received from the slave devices 110, 115 and 120 through the 2.4 GHz transceiver 205 (included in the radio signals having the frequency band of 2.4 GHz) The beacon signal included in the beacon interval and the frequency included in the control signal interval when the calculated received signal strength value is greater than the reference received signal strength value, The superframe including the change signal is transmitted to each of the slave devices 110, 115 and 120 through the 2.4 GHz transceiver 205 so that the master device 105 and the slave device The frequency band used by each of the antennas 110, 115, and 120 may be changed to 900 MHz. The reference received signal strength value may be a reference value stored in the master device 105, for example, -50 (dBm).

In another embodiment, the MCU unit 215 receives the 2.4-GHz frequency band wireless communication signals (or 2.4-GHz frequency signals) received via the 2.4-GHz transceiver 205 from each of the slave devices 110, (LQI) value for a beacon signal included in the beacon period when the calculated link quality index value is smaller than the reference link quality index value, The superframe including the frequency change signal included in the control signal interval is transmitted to each of the slave devices 110, 115 and 120 through the 2.4 GHz transceiver 205, The frequency band used by each of the slave devices 110, 115, and 120 synchronizing with the beacon signal can be changed to 900 MHz. The reference link quality index (LQI) value may be, for example, 200 as a reference value stored in the master device 105.

1 to 7, a wireless group communication method according to an embodiment of the present invention will be described as follows.

The wireless group communication method includes a communication performing step, a calculating step, and a changing step. According to the communication performing step, the master device 105 and the slave devices 110, 115, and 120 respectively synchronize the slave devices 110, 115, and 120 with the master device 105 A super frame including a beacon period, a control signal period, and a data period including a beacon time slot for transmitting a beacon signal is used to perform wireless audio communication with each other in the 2.4 GHz frequency band.

According to the calculation step, the master device 105 transmits a radio communication signal (beacon signal included in the radio signal having the 2.4 GHz frequency band) in the 2.4 GHz frequency band received from each of the slave devices 110, 115 and 120 0.0 &gt; (RSSI) &lt; / RTI &gt;

According to the changing step, if the master device 105 determines that the received signal strength value calculated in the calculating step is greater than the reference received signal strength value, the beacon signal included in the beacon period and the frequency varying signal included in the control signal period 115 and 120 to each of the master devices 105 and the slave devices 110, 115, and 120 to 900 MHz by transmitting a super frame including the slave devices 110, 115, and 120 to the slave devices 110, The reference received signal strength value may be a reference value stored in the master device 105, for example, -50 (dBm).

1 to 7, a wireless group communication method according to another embodiment of the present invention will be described as follows.

The wireless group communication method includes a communication performing step, a calculating step, and a changing step. According to the communication performing step, the master device 105 and the slave devices 110, 115, and 120 respectively synchronize the slave devices 110, 115, and 120 with the master device 105 A super frame including a beacon period, a control signal period, and a data period including a beacon time slot for transmitting a beacon signal is used to perform wireless audio communication with each other in the 2.4 GHz frequency band.

According to the calculating step, the master device 105 transmits a radio communication signal in the 2.4 GHz frequency band (or a beacon signal included in the radio signal having the 2.4 GHz frequency band) received from each of the slave devices 110, 115, Lt; RTI ID = 0.0 &gt; (LQI) &lt; / RTI &gt;

According to the changing step, when the link quality index value calculated in the calculating step is smaller than the reference link quality index value, the master device 105 transmits the beacon signal included in the beacon period and the frequency change signal included in the control signal period 115 and 120 to each of the master devices 105 and the slave devices 110, 115, and 120 to 900 MHz by transmitting a super frame including the slave devices 110, 115, and 120 to the slave devices 110, The reference link quality index (LQI) value may be, for example, 200 as a reference value stored in the master device 105.

The components or &quot; units &quot; or blocks or modules used in the present embodiment may be implemented in software such as a task, a class, a subroutine, a process, an object, an execution thread, , A field programmable gate array (FPGA), or an application-specific integrated circuit (ASIC), or a combination of the above software and hardware. The components or parts may be included in a computer-readable storage medium, or a part of the components may be dispersed in a plurality of computers.

As described above, the embodiments have been disclosed in the drawings and specification. Although specific terms are used herein, they are used for the purpose of describing the present invention only and are not used to limit the scope of the present invention described in the claims or the claims. It is therefore to be understood by those skilled in the art that various modifications and equivalent embodiments may be made without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

105: Master device
110: Slave device
115: Slave device
120: Slave device
202: 2.4 GHz antenna section
204: 900 MHz antenna unit
205: 2.4 GHz transceiver
210: 900 MHz transmission /
215: MCU unit
220: Audio codec unit

Claims (12)

A wireless group communication system comprising:
A master device; And
And slave devices each performing wireless group communication with the master device in synchronization with a beacon signal transmitted through each of the beacon time slots from the master device,
Each of the master device and the slave devices performs group call communication in a frequency band of 2.4 GHz or 900 MHz using a super frame including a beacon period, a control signal period, and a data period including the beacon time slots ,
Wherein the master device transmits a super frame including a beacon signal included in the beacon period and a frequency change signal included in the control signal interval to each of the slave devices according to a predetermined criterion, A wireless group communication system for changing a frequency band used by each of slave devices. The method according to claim 1,
The master device calculates a Received Signal Strength Indication value for a wireless communication signal of the 2.4 GHz frequency band received from each of the slave devices, A superframe including a beacon signal included in the beacon interval and a frequency change signal included in the control signal interval is transmitted to each of the slave devices, so that each of the master device and the slave devices A wireless group communication system that changes the frequency band used to 900 MHz. 3. The method of claim 2,
Wherein the master device transmits the superframe including the frequency change signal five times. The method according to claim 1,
Wherein the master device calculates a link quality indicator value for a radio communication signal of the 2.4 GHz frequency band received from each of the slave devices, A superframe including a beacon signal included in the beacon period and a frequency change signal included in the control signal interval is transmitted to each of the slave devices when the master device and the slave devices are used, To 900 MHz. &Lt; / RTI &gt; 5. The method of claim 4,
Wherein the master device transmits the superframe including the frequency change signal five times. The apparatus according to claim 1,
A 2.4 GHz transceiver for transmitting or receiving a radio communication signal in the 2.4 GHz frequency band;
A 900 MHz transceiver for transmitting or receiving a radio communication signal in the 900 MHz frequency band;
An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And
The 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the MCU unit for controlling the operation of the audio codec unit
The wireless group communication system comprising: 7. The apparatus of claim 6, wherein each of the slave devices comprises:
A 2.4 GHz transceiver for transmitting or receiving a radio communication signal in the 2.4 GHz frequency band;
A 900 MHz transceiver for transmitting or receiving a radio communication signal in the 900 MHz frequency band;
An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And
The 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the MCU unit for controlling the operation of the audio codec unit
The wireless group communication system comprising: A wireless group communication apparatus which is a master apparatus for a wireless group communication system,
A 2.4 GHz transceiver for transmitting or receiving a radio communication signal in a 2.4 GHz frequency band through a super frame including a beacon period, a control signal period, and a data period;
A 900 MHz transceiver for transmitting or receiving a wireless communication signal in a 900 MHz frequency band through a super frame including a beacon period, a control signal period, and a data period;
An audio CODEC for encoding an audio signal input through a microphone and for decoding an audio signal included in a wireless communication signal received through the 2.4 GHz transceiver or the 900 MHz transceiver; And
And an MCU unit for controlling operations of the 2.4 GHz transceiver unit, the 900 MHz transceiver unit, and the audio codec unit,
The MCU unit,
And controls the 2.4 GHz transceiver and the 900 MHz transceiver to operate based on a wireless communication signal included in the super frame received through the 2.4 GHz transceiver or the 900 MHz transceiver,
The master device controls the slave devices to transmit the super frame including the beacon signal included in the beacon period and the frequency change signal included in the control signal interval through the 2.4 GHz transceiver according to a predetermined criterion Thereby changing the frequency band used by each of the slave devices synchronizing with the master device and the beacon signal to 900 MHz. 9. The method of claim 8,
The MCU unit calculates a received signal strength (RSSI) value for a 2.4-GHz frequency band wireless communication signal received from each of the slave devices via the 2.4 GHz transceiver unit, The beacon signal included in the beacon interval and the frequency change signal included in the control signal interval are transmitted to the slave devices through the 2.4 GHz transceiver when the received superframe is greater than the intensity value, And changes the frequency band used by each of the master device and the slave devices synchronizing with the beacon signal to 900 MHz. 9. The method of claim 8,
Wherein the MCU unit calculates a link quality index (LQI) value for the 2.4GHz frequency band wireless communication signal received from each of the slave devices through the 2.4GHz transceiver unit, And transmitting a superframe including the beacon signal included in the beacon period and the frequency change signal included in the control signal interval to each of the slave devices through the 2.4 GHz transceiver when it is smaller than the exponent value, And changes the frequency band used by each of the master device and the slave devices synchronizing with the beacon signal to 900 MHz. A wireless group communication method comprising:
(a) a super frame including a beacon period, a control signal period, and a data period including a beacon time slot for transmitting a beacon signal for synchronizing each of the slave devices with the master device, Performing wireless audio communication in a frequency band of 2.4 GHz using the wireless audio communication;
(b) calculating, by the master device, a received signal strength (RSSI) value for a wireless communication signal of a 2.4 GHz frequency band received from each of the slave devices; And
(c) if the received signal strength value calculated in step (b) is greater than a reference received signal strength value, the master device includes a beacon signal included in the beacon period and a frequency change signal included in the control signal period To each of the slave devices, changing the frequency band of use of each of the master device and the slave devices to 900 MHz
The method comprising the steps of: A wireless group communication method comprising:
(a) a super frame including a beacon period, a control signal period, and a data period including a beacon time slot for transmitting a beacon signal for synchronizing each of the slave devices with the master device, Performing wireless audio communication in a frequency band of 2.4 GHz using the wireless audio communication;
(b) calculating, by the master device, a link quality index (LQI) value for a wireless communication signal in the 2.4 GHz frequency band received from each of the slave devices; And
(c) the master device includes a beacon signal included in the beacon period and a frequency change signal included in the control signal interval when the link quality index value calculated in step (b) is smaller than the reference link quality index value To each of the slave devices, changing the frequency band of use of each of the master device and the slave devices to 900 MHz
The method comprising the steps of:

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