Radio communication system, control method for radio communication system, and control program for radio communication system

Abstract

To provide a radio communication system capable of receiving audio data without trouble even if a radio base station is switched.SOLUTION: Each radio base station includes a ring buffer provided correspondingly to each radio terminal including a first radio terminal which is connected to the own station and a second radio terminal which is not connected to the own station, and comprises a buffer management section by which audio data included in a received audio packet are written in a region designated by a write index in the ring buffer provided correspondingly to the radio terminal of a destination to transmit the audio data and audio data written in a region designated by a read index in the ring buffer provided correspondingly to the first radio terminal are read out.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wireless communication system, a control method for a wireless communication system, and a wireless communication system Regarding the control program. [Background technology]

[0002] As described in Patent Document 1, a wireless communication system called an intercom system These systems are being used in stores and other places. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-165378 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, constructing a wireless communication system using wireless LAN communication standards (IEEE802.11, etc.) This is not limited to wireless LAN, but applies to wireless communications that use a specific communication standard for data communication. In a communication system, even if the wireless base station to which a wireless terminal is connected is switched, there is no problem. It is required to be able to receive voice data quickly.

[0005] The present invention is capable of transmitting voice data without any problems even when the wireless base station to which the wireless terminal is connected is switched. The present invention aims to provide a wireless communication system capable of receiving data. [Means for solving the problem]

[0006] A wireless communication system according to an aspect of the present invention includes a center device and multiple devices connected to the center device. A plurality of wireless base stations and one or more wireless terminals connected wirelessly to each of the wireless base stations and a center device that receives voice data and a destination to which the voice data is to be transmitted. The sequence number indicates the order of voice data transmitted from each wireless terminal. The voice packet is transmitted to all of the wireless base stations, and each wireless base station receives the voice packet from the The first wireless terminal connected to the station and the second wireless terminal not connected to the station are supported by the The audio data included in the received audio packet is stored in a ring buffer. The data is stored in a ring buffer provided corresponding to the destination wireless terminal to which the voice data is to be transmitted. The write index is written into the area designated by the write index, and the The audio data written to the area specified by the read index of the ring buffer and a buffer management unit that reads out the

[0007] A wireless communication system according to an embodiment of the present invention includes: The method of controlling the system is as follows: the center device transmits voice data and a wireless communication device to which the voice data is to be transmitted. A voice packet that includes multiple pairs of a sequence number that indicates the order of voice data transmitted by each terminal. a step of transmitting the packet to all of a plurality of wireless base stations connected to the center device; The wireless base station detects a first wireless terminal connected to the wireless base station and a second wireless terminal not connected to the wireless base station. A ring buffer is provided for each wireless terminal, and the received The voice data contained in the voice packet is sent to the wireless terminal to which the voice data is to be sent. The data is written to the area specified by the write index in the ring buffer. A read index of a ring buffer provided corresponding to the first wireless terminal is specified. and reading out the audio data written in the area.

[0008] A wireless communication system according to an embodiment of the present invention includes: The control program of the system is such that the center device determines voice data and destinations to which the voice data is to be sent. A voice data set including a sequence number indicating the order of voice data transmitted by each wireless terminal. transmitting the voice packets to all of a plurality of wireless base stations connected to the center device; Then, each wireless base station detects a first wireless terminal connected to the wireless base station and a second wireless terminal not connected to the wireless base station. A ring buffer is provided for each of the wireless terminals including the second wireless terminal, The voice data contained in the received voice packet is sent to the wireless terminal Write to the area specified by the write index of the ring buffer that corresponds to the and a read index of the ring buffer provided corresponding to the first wireless terminal. and reading out the audio data written in the specified area. Effect of the Invention

[0009] According to the wireless communication system of the present invention, the wireless base station to which the wireless terminal is connected is switched. Even if the signal is lost, audio data can still be received without any problems. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an example of the overall configuration of a wireless communication system according to an embodiment; [Diagram 2] 2 is a block diagram showing an example of the configuration of a center device in the wireless communication system of the embodiment; [Diagram 3] 1 is a block diagram showing an example of the configuration of a wireless base station in a wireless communication system according to an embodiment; [Figure 4] 1 is a block diagram showing an example of the configuration of a wireless terminal in a wireless communication system according to an embodiment; [Diagram 5] 1 is a conceptual diagram showing a base station management table managed by a base station management unit of a center device. [Figure 6] 11 is a conceptual diagram showing a terminal information table managed by a wireless terminal management unit of the center device. FIG. [Figure 7] 10 is a sequence diagram showing a communication sequence when a wireless terminal connects to a wireless base station and a center device registers the wireless terminal. FIG. [Figure 8] 11 is a conceptual diagram showing a wireless terminal registration request transmitted from a wireless terminal to a center device. FIG. [Figure 9] 1 is a conceptual diagram showing terminal information of a wireless terminal that a center device transmits to a wireless base station. [Figure 10] 1 is a conceptual diagram showing a wireless terminal information table managed by a wireless terminal management unit of a wireless base station. [Figure 11] FIG. 11 is a sequence diagram showing a registration process executed between a center device and a wireless base station. [Figure 12] FIG. 13 is a conceptual diagram showing a radio base station registration response that the center device transmits to the radio base station. [Figure 13] 10 is a sequence diagram showing an example of a voice data transmission / reception process executed between a center device, a wireless base station, and a wireless terminal; FIG. [Figure 14] 1 is a conceptual diagram showing an example of the structure of a multicast voice packet transmitted from a center device to a wireless base station; [Figure 15] 15 is a conceptual diagram showing an example of the configuration of terminal audio data of one wireless terminal included in aggregated audio data of the multicast audio packet shown in FIG. 14. FIG. [Figure 16] 1 is a conceptual diagram illustrating a ring buffer included in a buffer management unit of a wireless base station. [Figure 17] 1 is a conceptual diagram showing an example of the structure of a voice packet transmitted from a wireless base station to a wireless terminal; [Figure 18] 18 is a diagram showing an example of the configuration of a flag included in the voice packet shown in FIG. 17. [Figure 19] 18 is a diagram showing a specific example of the voice packet shown in FIG. 17. [Figure 20] FIG. 2 is a diagram showing reference timings at which a center device, a wireless base station, and a wireless terminal transmit voice packets. [Figure 21] 13 is a flowchart showing a transmission and reception process in a wireless base station. [Figure 22] 22 is a flow chart showing a receiving process of a multicast audio packet transmitted from a center device, out of the transmitting / receiving process in step S212 shown in FIG. [Diagram 23] 23 is a flowchart showing detailed processing of step S222 shown in FIG. 22. [Figure 24] 22 is a flowchart showing a receiving process of a voice packet transmitted from a wireless terminal, out of the transmitting and receiving process in step S212 shown in FIG. [Diagram 25] 22 is a flowchart showing a transmission process for transmitting voice packets to a center device and a wireless terminal, out of the transmission and reception process in step S212 shown in FIG. 21. [Figure 26] 26 is a flowchart showing a transmission process for transmitting a voice packet to the center device in step S252 shown in FIG. [Figure 27A] 26 is a partial flowchart showing a transmission process in which the wireless base station transmits a voice packet to the wireless terminal in step S252 shown in FIG. 25. [Figure 27B] 27B is a partial flowchart subsequent to FIG. 27A, showing the transmission process in which the wireless base station transmits a voice packet to the wireless terminal in step S252 shown in FIG. [Figure 27C] 27B is a partial flowchart subsequent to FIG. 27A, showing the transmission process in which the wireless base station transmits a voice packet to the wireless terminal in step S252 shown in FIG. [Figure 28] 10 is a flowchart showing a method by which a wireless terminal that has switched a wireless base station to which it is connected due to roaming acquires an IP address of the newly connected wireless base station. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following describes a wireless communication system, a control method for the wireless communication system, and a buffer pipe according to an embodiment of the present invention. The method for controlling the wireless communication system will be described with reference to the accompanying drawings. As shown in FIG. , center device 10, wireless base stations 20A, 20B, 20C, wireless terminals 30A, 30B, 30 The wireless base stations 20A to 20C are not specified, and the Any radio base station including other radio base stations not included in the above-mentioned system will be referred to as a radio base station 20. Without specifying any one of the wireless terminals 30A to 30D, other wireless terminals not shown in the figure It will be referred to as wireless terminal 30 .

[0012] The number of wireless base stations 20 and the number of wireless terminals 30 shown in FIG. The number of 0s and the number of wireless terminals 30 are not limited.

[0013] The center device 10 and the wireless base stations 20A to 20C are connected by a wired network 15N. The wireless base station 20 may be directly connected to the center device 10 or may be connected to other wireless The center device 10 may be connected to the wireless base station 20. The method of connection to the wireless base station 20 is not limited. The center device 10 manages the wireless base stations 20A to 20C and the wireless terminals 30A to 30D. The audio data received from the wireless terminals 30A to 30D via the Create voice data for a call.

[0014] The wireless communication ranges 40A, 40B, and 40C are defined by the wireless base station 20A, In FIG. 1, the wireless terminal 30A is connected to the wireless terminals 20B and 20C. The wireless terminal 30B is located within the wireless communication range 40A and is connected to the wireless base station 20A. The wireless terminal 30C is located within the wireless communication range 40B and is connected to the wireless base station 20B. and 30D are located within the wireless communication range 40C and are connected to the wireless base station 20C. The line communication ranges 40A, 40B, and 40C form a wireless network.

[0015] The wireless communication between the wireless base stations 20A to 20C and the wireless terminals 30A to 30D is performed by a wireless LAN. It complies with the IEEE802.11 communications standard.

[0016] As shown in FIG. 2, the center device 10 includes a receiving unit 11, a received data processing unit 12, a base station management unit, and a base station control unit. management unit 13, voice data processing unit 14, wireless terminal management unit 15, transmission cycle management unit 16, transmission data The data generating unit 17 and the transmitting unit 18 are connected to the receiving unit 11 by a solid arrow and to the transmitting unit 18 by a solid arrow. The solid arrows correspond to the wired network 15N connected to the wireless base station 20. The station management unit 13 manages the base station management table 130, and the wireless terminal management unit 15 manages the terminal information table 130. Manage Bull 150.

[0017] As shown in FIG. 3, the wireless base station 20 includes a receiving unit 21, a received data processing unit 22, and a synchronization management unit. a buffer management unit 24, a wireless terminal management unit 25, a transmission cycle management unit 26, a transmission data creation unit 27, The receiving unit 21 includes a receiving unit 27 and a transmitting unit 28. The arrow line corresponds to the wired network 15N connected to the wireless base station 20. The dashed and dotted arrows to the wireless terminal 30 and the dashed and dotted arrows from the transmitter 28 indicate wireless The buffer management unit 24 includes a buffer 240. The management unit 25 manages a wireless terminal information table 250 .

[0018] As shown in FIG. 4, the wireless terminal 30 includes a receiving unit 31, a received data processing unit 32, a synchronization management unit 33, a buffer management unit 34, a transmission cycle management unit 35, a transmission data creation unit 36, and a transmission unit 37. The dashed and dotted arrows to the receiving unit 31 and the dashed and dotted arrows from the transmitting unit 37 are The buffer management unit 34 corresponds to a wireless network with the wireless base station 20. 0.

[0019] The general operations of the center device 10, the wireless base station 20, and the wireless terminal 30 will be described below. The receiving unit 11 receives data from the wired network 15N. The receiving unit 11 receives data from the wireless base station 20 and transmits the data to the receiving unit 12. When the base station management unit 13 receives the wireless base station registration request, the base station management unit 13 The base station management unit 13 receives a wireless base station registration request from the wireless base station 20. 5, the base station management unit 13 assigns a base station ID to the base station P address. The base station ID and the IP address are stored in a management table 130 in pairs.

[0020] When the receiving unit 11 receives a wireless terminal registration request from the wireless base station 20, which will be described later, The terminal management unit 15 receives a wireless terminal registration request from the received data processing unit 12. The terminal management unit 15 assigns a terminal ID to the IP address of the wireless terminal 30. As shown in FIG. The wireless terminal management unit 15 receives the terminal ID, the IP address, the MAC address of the wireless terminal 30, and the buffer size of the playback buffer 340 are stored as a set in the terminal information table 150. The wireless terminal management unit 15 stores a voice message for each wireless terminal 30 to which the voice data is to be transmitted. The sequence number indicating the order of the voice data is managed.

[0021] The voice data processing unit 14 processes the voice data received by the receiving unit 11 to generate transmission data. The transmission cycle management unit 16 supplies the multicast audio packet to the multicast audio packet transmission unit 17. The transmission data creation unit 17 manages the timing. The transmission data is generated based on the voice data. The transmission data generation unit 17 transmits the transmission data to the plurality of wireless terminals 3. 0 to create a multicast audio packet. The transmitting unit 18 transmits the multicast audio packet to the wired network 15N.

[0022] An example of a multicast audio packet created by the audio data processing unit 14 is shown below. There are six wireless terminals 30A to 30F. Among them, the wireless terminals 30A to 30C belong to the communication group of group 1, and the wireless terminal 30D Assume that ~30F belongs to the call group of group 2.

[0023] The audio data processing unit 14 mixes the audio data received from the wireless terminals 30B and 30C. This voice data is then sent to the wireless terminal 30A as shown in FIG. The voice data processing unit 14 receives voice data from the wireless terminals 30A and 30C. The received voice data is mixed to generate voice data addressed to the wireless terminal 30B. The data processing unit 14 mixes the audio data received from the wireless terminals 30A and 30B. Then, voice data addressed to the wireless terminal 30C is created.

[0024] The aggregated voice data in FIG. 14, which will be described later, is addressed to the wireless terminal 30A, the wireless terminal 30B, and the wireless terminal 3 When including voice data addressed to 0C, the combination of terminal ID, sequence number, and voice data in Figure 15 is used. The aggregated voice data includes three of these.

[0025] The transmission data creation unit 17 converts the voice data sent from the voice data processing unit 14 to the voice data addressed to each wireless terminal 30. The data is used to create the multicast audio packet shown in Figure 14. The voice packet is not related to the group, and is addressed to a wireless terminal, for example, the wireless terminal 30C, which belongs to a different group. The audio data addressed to the wireless terminal 30D may be included in one multicast audio packet.

[0026] In FIG. 3, a receiver 21 receives multicast audio packets from a wired network 15N. The receiving unit 21 receives voice packets from the wireless network. The data processing unit 22 processes the data received by the receiving unit 21. As will be described later, the received data The processing unit 22 may analyze or judge the data received by the receiving unit 21. The transmission unit 23 generates a reference timing for the transmission unit 28 to transmit a voice packet, and controls the transmission period. The data is supplied to the management unit 26.

[0027] The buffer management unit 24 stores audio data in the buffer 240 and transfers the audio data from the buffer 240. The wireless terminal management unit 25 reads voice data from the wireless terminal and manages various data described later. The information of the wireless terminal 30 transmitted from the center device 10 and the information of the wireless terminal connected to the own station The information about the wireless terminal 30 is stored in the wireless terminal information table 250 to manage the wireless terminal 30.

[0028] The transmission cycle management unit 26 manages a transmission timer, which will be described later, and generates a transmission trigger, which will be described later. The transmission data creation unit 27 creates transmission data and supplies it to the transmission unit 28. transmits data to a wired network 15N or a wireless network.

[0029] In FIG. 4, a receiving unit 31 receives data from a wireless network. The control unit 32 processes the data received by the receiving unit 31. The synchronization control unit 33 controls the sending unit 37 to It generates a reference timing for transmitting voice packets and supplies it to the transmission cycle management unit 35. The buffer manager 34 manages a playback buffer 340 that stores audio data. The control unit 35 manages the timing of transmitting voice packets. The transmission unit 37 transmits the transmission data created by the transmission data creation unit 36 ​​via the wireless network. Send data to the network.

[0030] In FIG. 7, a wireless terminal 30A is connected to a wireless base station 20A, and a center device 10 is connected to the wireless terminal 30. 1 shows a communication sequence for registering the wireless terminal 30A. In step S71, the wireless terminal 30A The wireless base station 20A transmits a connection request to the wireless base station 20A, and in step S72, the wireless base station 20A receives a connection response. The wireless terminal 30A then transmits the response to the wireless terminal 30A. Steps S71 and S72 are executed by the wireless base station 20A and the wireless terminal 30A. This is the connection process.

[0031] In step S73, the wireless terminal 30A transmits a wireless terminal registration request R to the center device 10. As shown in FIG. 8, the wireless terminal 30A transmits the signal 73 to the center device 1 in step S73. The wireless terminal registration request R73 sent to the wireless terminal 30A includes the MAC address and The buffer size of the playback buffer 340 of the wireless terminal 30A is included. The center device 10 that has received the message R73 transmits the message R73 via the wireless base station 20A in step S74. Then, the center device 10 transmits a wireless terminal registration response to the wireless terminal 30A. A terminal ID is assigned to the wireless terminal 30A. As a result, the center device 10 Register.

[0032] Steps S73 and S74 are performed by the center device 10 and the wireless terminal 30A. This is the final registration process.

[0033] In steps S75, S76, and S77, the center device 10 I30A are transmitted to the wireless base stations 20A, 20B, and 20C, respectively. As shown in FIG. The terminal information I30A includes the terminal ID of the wireless terminal 30A assigned by the center device 10, The IP address, MAC address, and buffer size of the wireless terminal 30A. The MAC address and buffer size of the received wireless terminal registration request R73 are The IP address of the wireless terminal 30A is registered in the wireless terminal registration request R 73 can be obtained when receiving the

[0034] FIG. 10 shows a wireless terminal information table 25 managed by the wireless terminal management unit 25 of the wireless base station 20. 0. The receiver 21 of the wireless base station 20A to 20C receives the terminal information I30A shown in FIG. Upon receiving the terminal information I30A, the received data processor 22 supplies the terminal information I30A to the wireless terminal manager 25. The wireless terminal management unit 25 stores the terminal ID and IP address of the wireless terminal 30A in the wireless terminal information table 250. The wireless base station 20 stores the address, MAC address, buffer size, and reception time. If the receiving unit 21 of each of the wireless terminals A to C similarly receives the terminal information I30 of the other wireless terminals 30, The terminal information table 250 stores the terminal IDs, IP addresses, and MAC addresses of multiple wireless terminals 30. The address, buffer size, and time of receipt are saved.

[0035] FIG. 11 shows a registration process executed between the center device 10 and the wireless base station 20A. In step S111, the wireless base station 20A transmits a wireless base station registration request to the center device 10. As described above, the receiver 11 of the center device 10 transmits the radio base station registration When the registration request R111 is received, the base station management unit 13 checks the base station management table shown in FIG. The base station ID and the IP address are stored in a pair in the transmission unit 18 of the center device 10. In step S112, the wireless base station registration response R112 is sent to the wireless base station 20A. Believe.

[0036] As shown in FIG. 12, the wireless base station registration response R112 includes the The assigned base station ID, the wireless terminal connected to the center device 10 via the wireless base station 20, The number of connected terminals is the number of terminals of the wireless terminal 30, and the terminal information I30 of the connected wireless terminal 30 is The wireless terminals 30A, 30B and one or more other wireless terminals Assume that the terminal 30 is connected to the center device 10. At this time, the connected terminal information is The terminal information I30A of the wired terminal 30A, the terminal information I30B of the wireless terminal 30B, and one or more other includes terminal information I30 of the wireless terminal 30 or more.

[0037] 13, the communication between the center device 10, the wireless base station 20, and the wireless terminal 30 will be described. An example of a process for transmitting and receiving voice data will be described. In step S1301, the center device 10 The multicast voice packet including the voice data addressed to the wired terminal 30A and the wireless terminal 30B is transmitted to the wireless terminal 30B. The received signal is then transmitted to the radio base stations 20A to 20C by multicast.

[0038] In step S1302, the center device 10 receives voice messages addressed to the wireless terminals 30C and 30D. Multicasting a multicast voice packet including the data to the wireless base stations 20A to 20C. Send with.

[0039] In this manner, the voice data addressed to the multiple wireless terminals 30 is multicast to each of the wireless base stations 20. will be sent to.

[0040] In step S1303, the wireless base station 20A receives the data from the wireless terminal 30A and buffers it. The voice data being received is transmitted to the center device 10 as a voice packet. In step S1304, A receives the multicast voice packet from the center device 10 in step S1301. The voice data addressed to the wireless terminal 30A that has received and buffered voice packets is converted into voice packets. to the wireless terminal 30A.

[0041] In step S1305, which is the same as step S1304, the wireless base station 20B The wireless terminal that receives and buffers the multicast audio packets from the network device 10. The voice data addressed to the wireless terminal 30B is transmitted to the wireless terminal 30B as a voice packet.

[0042] In step S1306, the wireless base station 20B receives the data from the wireless terminal 30B and buffers it. The voice data being received is transmitted to the center device 10 as a voice packet. In steps S1307 and S1308, C receives the packets from the wireless terminals 30C and 30D, respectively. The buffered voice data is transmitted to the center device 10 as voice packets.

[0043] In step S1309, the wireless terminal 30A transmits the voice data as a voice packet to the wireless base station. In step S1310, the wireless terminal 30B transmits the voice data to the wireless terminal 20A. The received signal is transmitted to the wireless base station 20B as a

[0044] The center device 10, the wireless base stations 20A and 20B, and the wireless terminals 30A and 30B are Steps S1311 to S1320 are executed which are similar to steps S1301 to S1310.

[0045] FIG. 14 shows the information transmitted to the wireless base stations 20A to 20C in steps S1301, S1302, S1311, and S1312. The multicast audio packet is sent via the wireless A synchronization flag indicating that the packet is the basis for the transmission timing of the base station 20, The number of terminals indicates the number of terminal voice data included in the packet, and the number of terminals indicates the number of terminal voice data included in the packet. The aggregated voice data includes aggregated voice data generated by the wireless terminals 30 indicated by the terminal number. If the number of terminals is 0, the multicast audio packet contains the aggregated audio data. Does not include data.

[0046] FIG. 15 shows the structure of terminal voice data of one wireless terminal 30 included in the aggregated voice data. The terminal voice data is the destination of the voice data included in the aggregate voice data. The terminal ID of the wireless terminal 30, a sequence indicating the order of the voice data managed for each wireless terminal 30 A multicast audio packet consists of a sequence number and one period of audio data. The number of terminal voice data to be included in the packet is set to a size that does not cause fragmentation in IP communication. may be limited to.

[0047] As shown in FIG. 16, the buffer 240 includes a ring buffer 240R. Although only one ring buffer 240R is shown, the buffer 240 may be multiplexed for each wireless terminal 30. The ring buffer 240R has a buffer index It has four areas that can be selected by sequence number 0 to 3, and four sets of sequence numbers and sounds. The four areas of the ring buffer 240R can store the most recently transmitted voice data. Area for writing audio data from the audio data of a certain period to the audio data of a certain period before (here, 3 periods before) It is.

[0048] The buffer management unit 24 cycles through the buffer indexes 0 to 3 according to the write index. By specifying the address, you can specify the area where the sequence number and audio data are written. The buffer management unit 24 can set the buffer index to 0 according to the read index. By specifying ~3 cyclically, the area from which the sequence number and audio data are read can be specified. The buffer management unit 24 can specify the write index and the read index. The write index and the read index are not synchronized.

[0049] When the wireless base station 20 receives a multicast voice packet from the center device 10, The ring buffer manager 24 stores the ring buffer 24 corresponding to the terminal ID of the wireless terminal 30 shown in FIG. 0R and save the sequence number and the voice data. In FIG. 16, the write index Since the buffer index is 2, the buffer management unit 24 writes the sequence number Write the signal and audio data.

[0050] The wireless terminal management unit 25 detects a multicast group having a synchronization flag set as shown in FIG. The time when the voice packet was received is stored in the terminal ID of the wireless terminal information table 250 shown in FIG. The received time is stored as the corresponding received time.

[0051] In FIG. 16, since the read index is 1, the wireless base station 20 reads the ring buffer 240 When transmitting the voice data stored in the buffer R to the wireless terminal 30, the buffer management unit 24 reads the sequence number and audio data from the area with buffer index 1.

[0052] FIG. 17 shows the tones that the wireless base station 20A transmits to the wireless terminal 30A in steps S1304 and S1314. The voice packet is the voice packet that the wireless base station 20B transmits to the wireless terminal 30B in steps S1305 and S1315. 2 shows an example of the configuration of a voice packet.

[0053] The voice packet is transmitted to the wireless terminal 30 via the wireless base station 20. The sequence number stored in the area specified by the buffer index indicated by this The voice packets are transmitted in the order shown in FIG. The received time corresponding to the terminal ID in the wireless terminal information table 250 shown in FIG. The audio packet also contains a flag indicating the lay time and the information of the audio data included. The audio data stored in the area specified by the buffer index indicated by the index. The multiplexed audio data may include a plurality of audio data. do.

[0054] FIG. 18 shows an example of the configuration of the flag included in the voice packet shown in FIG. As shown in 18, the flag consists of 8 bits of data. The bit marked N is the most significant bit. The least significant bit is the bit marked N-7, and the most significant bit is the bit marked N-8. The sequence number is the audio data of the audio packet (the buffer index in Figure 16). This indicates whether the multiplexed voice data in the voice packet is included in the voice data in the voice packet. The second bit, marked N-1, is the sequence number included in the audio packet. Is the audio data of the sequence number one period before the sequence number included in the multiplexed audio data? Indicates whether or not.

[0055] Similarly, the 3rd to 7th bits, denoted as N-2 to N-6, are 2 to 7, respectively. Indicates whether the audio data of the sixth sequence number before is included in the multiplexed audio data. The most significant bit indicates that the audio data of the sequence number 7 periods ago is included in the multiplexed audio data. If audio data is included in the multiplexed audio data, the value of each bit is “ If audio data is not included in the multiplexed audio data, the value of each bit is “0 " is.

[0056] For example, if the flag is “11110111”, it will play the sound with the sequence number three periods before. The voice data is not included in the multiplexed voice data, and the voice data of other sequence numbers is included in the multiplexed audio data.

[0057] The multiplexed audio data included in the audio packet shown in FIG. 17 is the audio data indicated by the flag. Flags are not limited to 8 bits and can be other sizes. This is also fine.

[0058] FIG. 19 shows a specific example of the voice packet shown in FIG. 17. As shown in FIG. The message ID is 10, the sequence number is 3000, the delay time is 5, and the flag is 0000010. 1. Because the flag is 00000101, the multiplexed audio data is The audio data of 3000 and the audio data of sequence number 2998, which is the sequence two periods before. The voice packet shown in FIG. 19 includes voice data with sequence number 3000 and sequence number 3000. The audio data includes multiplexed audio data in which the audio data with sequence number 2998 is concatenated in this order.

[0059] FIG. 20 shows a case in which a center device 10, a wireless base station 20, and a wireless terminal 30 transmit voice packets. The center device 10 determines the first reference timing of the transmission period P1. CT1, CT2, etc. start transmitting multicast voice packets to the wireless base station 20. When the first reference times CT1, CT2, . . . arrive, the printer 10 performs the following steps as shown in FIG. A synchronization flag is set at the beginning of the packet so that the packet is addressed to all wireless terminals 30, the number of which is indicated by the number of terminals. The aggregated audio data is transmitted via multicast.

[0060] The wireless base station 20 uses the second reference timings AT1, AT2, ... of the transmission period P1 as a reference. The wireless base station 20 transmits voice packets to the center device 10 and the wireless terminal 30. The offset time d1 from the time when the flagged multicast audio packet was received The points in time when the time has elapsed are defined as second reference times AT1, AT2, . . .

[0061] In detail, the wireless base station 20 transmits the base station ID at the second reference timings AT1, AT2, . . . At the added time, the voice packet is transmitted to the center device 10. 0 can shift the timing of transmitting voice packets to the center device 10. A different value is added to each wireless base station 20 other than the base station ID to the reference timing AT1, AT2, ... The timing of transmitting voice packets to the center device 10 may be shifted by calculating the delay time.

[0062] A plurality of wireless base stations 20 stagger the timing of transmitting voice packets to the center device 10. This makes it possible to avoid collisions of voice packets in the wired network 15N, and There is almost no data loss of voice data.

[0063] The wireless base station 20 transmits voice packets to the wireless terminal 30 at second reference times AT1, AT2, . . . That is, all the wireless base stations 20 start transmitting the wireless terminals at the same timing. The voice packet is sent to the terminal 30.

[0064] The wireless terminal 30 transmits the signal to the wireless base station at the third reference timings ST1, ST2, . . . of the transmission period P1. The third reference timings ST1, ST2, . . . are the second reference timings ST1, ST2, . . . The offset time d2 has elapsed from the reference timings AT1, AT2, .... The line terminal 30 calculates the time stamp as shown in FIG. 17 based on the reception time of the voice packet transmitted from the wireless base station 20. Subtract the delay time included in the voice packet and add offset times d1 and d2. The points in time at which this is done are defined as third reference times ST1, ST2, . . .

[0065] Next, even if the wireless terminal 30 switches the wireless base station 20, the wireless terminal 30 always receives the latest voice data. A method for reducing interruptions in voice during roaming will be described. The wireless base stations 20A to 20C connected to the center device 10 receive the multicast voice Receive a packet.

[0066] Each wireless base station 20 receives voice messages addressed to a wireless terminal 30 (a first wireless terminal) connected to the wireless base station. The data is transmitted to the ring back terminal 30 connected to the local station. Each wireless base station 20 stores the received signal in a ring buffer 240R (first ring buffer). The voice data addressed to the wireless terminal 30 (second wireless terminal) that is not connected to the own station is The ring buffer 240R (second ring buffer) provided in correspondence with the wireless terminal 30 not having the Save it in the

[0067] The wireless base station 20 transmits the received signal to the wireless terminal 30 connected to the wireless base station 20 in the ring buffer 240R. Connect to your station to transmit the stored voice data as voice packets at the transmission cycle P1. The read index of the ring buffer 240R provided in correspondence with the wireless terminal 30 is The wireless base station 20 updates the packet every transmission period P1. Since there is no need to transmit voice packets to terminal 30, wireless terminal 3 that is not connected to the own station 0, the read index of the ring buffer 240R is not updated. It is possible that...

[0068] However, this would prevent the wireless terminal 30 from roaming to another wireless base station 20 (another When the wireless base station 20 is switched from the wireless terminal 30 to the wireless terminal 30, the latest voice data is It is not possible to transmit

[0069] Therefore, the buffer management unit 24 of each wireless base station 20 determines whether the wireless terminal 3 connected to the wireless base station The read index of the ring buffer 240R corresponding to the transmission period P1 Not only does it update the data every time the station is connected to the wireless terminal, but it also updates the data every time the station is connected to another station. The read index of the ring buffer 240R corresponding to the transmission period P Update every 1.

[0070] After updating the read index of the ring buffer 240R, the buffer management unit 24 automatically The ring buffer 240R provided for the wireless terminal 30 not connected to the station Clears the sequence number pointed to by the read index.

[0071] Clearing the sequence number means resetting the sequence number to an invalid value, "-1". The read index is used to invalidate the voice data to be transmitted in the next transmission period P1. 13 indicates the buffer index of the ring buffer 240R that contains the data.

[0072] In this manner, each wireless base station 20 detects whether the wireless terminal 30 is roaming to another wireless base station. When the wireless base station 20 is switched from the base station 20 to the wireless terminal 30, the latest Audio data can be transmitted.

[0073] In addition, the arrival of voice data transmitted from the center device 10 to the wireless base station 20 is delayed, No audio data has been written to the buffer index area pointed to by the read index. By clearing the sequence number, the buffer pointed to by the read index It is possible to determine whether or not audio data is written in the index area.

[0074] A second reference timing that is a reference for the timing at which the wireless base station 20 transmits a voice packet The groups AT1, AT2, ... are the same for all the wireless base stations 20. Therefore, for each transmission period P1, The read index of the ring buffer 240R provided for each wireless terminal 30 is By updating the frequency, the voice data to be transmitted to the wireless terminal 30 between the wireless base stations 20 can be synchronized. This can be done.

[0075] The flowchart shown in FIG. 21 shows a transmission / reception process in the wireless base station 20. When the process is started, the wireless base station 20 executes a timing synchronization process in step S211. In step S212, the transmission / reception process is executed, and the process ends.

[0076] Specifically, the receiving unit 21 receives a multi-channel signal with a synchronization flag set from the center device 10. When the multicast voice packet is received, in step S211, the received data processing unit 22 The received data is analyzed, and the synchronization management unit 23 determines the second reference timings AT1, AT2, . . . The transmission cycle management unit 26 generates the transmission cycle and supplies it to the transmission cycle management unit 26. The transmission cycle management unit 26 starts a transmission timer. The transmission timer is a timer that expires every transmission period P1. The receiving unit 21 and the transmitting unit 28 In step S212, the multicast voice packet transmitted from the center device 10 is The center device 10 and the wireless terminal 30 receive voice packets. The voice packet is transmitted to the terminal 30.

[0077] The flowchart shown in FIG. 22 is a flow chart of the transmission / reception process in step S212 shown in FIG. The figure shows the reception process of a multicast audio packet transmitted from the center device 10. When the process is started, the receiving unit 21 receives the message transmitted from the center device 10 in step S221. The buffer management unit 24 receives the multicast audio packet. Then, the audio data of the received multicast audio packet is stored in the buffer 240 .

[0078] The flowchart shown in FIG. 23 shows the detailed process of step S222 shown in FIG. When the process starts, the received data processor 22 performs a step S231 to It is determined whether the number of pieces of voice data is 1 or more. The number of wireless terminals 30 indicated by the number of terminals If processing of all the audio data has not been completed, the number of unprocessed audio data is one or more. If the number of unprocessed voice data is 1 or more (YES), the buffer management unit 24 proceeds to step S2 At 32, the ring buffer 240R corresponding to the terminal ID of the wireless terminal 30 is selected.

[0079] In step S233, the buffer management unit 24 stores the sound in the selected ring buffer 240R. In step S234, the buffer management unit 24 stores the sequence number. The buffer management unit 24 stores the ring buffer 240R in step S235. The untransmitted data stored in the transfer buffer 240R and not yet transmitted to the wireless terminal 30 is The received data processing unit 22 updates the number of pieces of data by incrementing the number of pieces of data by 1 in step S23. In step S6, the number of unprocessed voice data is updated to be decremented by 1, and the process returns to step S2. Change it back to 31.

[0080] If the number of unprocessed voice data is not 1 or more in step S231 (NO), the number of terminals is This means that the processing of all the voice data for the wireless terminals 30 has been completed. The base station 20 ends the process.

[0081] The flowchart shown in FIG. 24 is a flow chart of the transmission / reception process in step S212 shown in FIG. This shows the reception process of a voice packet transmitted from the wireless terminal 30. When the process starts, In step S241, the receiving unit 21 receives a voice packet transmitted from the wireless terminal 30. In step S242, the buffer management unit 24 transfers the voice data of the received voice packet. The received data processor 22 stores the received data in the ring buffer 240R. The number of data pieces not yet transmitted to the center device 10 is updated to increment by 1, and the process is continued. Terminate.

[0082] The flowchart shown in FIG. 25 is a flow chart of the transmission / reception process in step S212 shown in FIG. The transmission process for transmitting voice packets to the center device 10 and the wireless terminal 30 is shown. When the transmission period starts, the transmission cycle management unit 26 receives the reference timing from the synchronization management unit 23, In step S251, a transmission timer is started, and when the transmission timer expires, a transmission trigger is issued. When the transmission timer expires, a transmission trigger is generated. The transmission unit 28 performs the process in step S25. In step 2, the voice packet is transmitted to the center device 10 and the wireless terminal 30, and the process is terminated. .

[0083] The flow chart shown in FIG. 26 is a flow chart showing the process of sending a sound to the center device 10 in step S252 shown in FIG. When the process starts, the buffer management unit 24 In step S261, it is determined whether the number of unsent data is 1 or more. If the number of pieces of data is 1 or more (YES), the transmission data creation unit 27 performs the transmission data creation in step S262. In step S263, the transmitting unit 28 generates a voice packet to be transmitted. In step S264, the buffer management unit 24 transmits the unprocessed packet to the center device 10. The number of pieces of transmission data is updated to be incremented by 1, and the process returns to step S261.

[0084] If the number of untransmitted data is not 1 or more in step S261 (NO), the wireless base station 20 End the process.

[0085] By the transmission process shown in FIG. 26, the wireless base station 20 buffers the data in the buffer 240. The voice data received from each of the wireless terminals 30 in communication with the center device 10 is transmitted to the center device 10.

[0086] The flowcharts shown in FIGS. 27A to 27C are the steps in which the wireless base station 20 performs the steps shown in FIG. A transmission process for transmitting a voice packet to the wireless terminal 30 is shown in step S252.

[0087] In FIG. 27A, when the process starts, the buffer management unit 24 performs the following in step S2701: Then, it is determined whether the number of wireless terminals 30 to which a signal has not yet been transmitted (hereinafter, “non-transmitting terminals”) is 1 or more. If the number of transmitting terminals is 1 or more (YES), the buffer management unit 24 performs the voice The buffer management unit 24 selects a wireless terminal 30 (transmitting terminal) that transmits a voice packet. In step S2703, the number of unsent data addressed to the wireless terminal 30 selected in step S2702 is 1 or more. It is determined whether or not

[0088] If the number of unsent data is 1 or more in step S2703 (YES), the buffer management unit 24 In step S2704, it is determined whether this is the first transmission after wireless terminal 30 is connected. That is, the buffer management unit 24 determines whether the voice packet to be transmitted is received by the wireless terminal 30. The first voice packet that the wireless base station 20 transmits to the wireless terminal 30 after connecting to the base station 20. It is determined whether or not there is a

[0089] If it is the first transmission in step S2704 (YES), the transmission data creation unit 27 proceeds to step S2 In 705, the latest system pointed to by the read index stored in the ring buffer 240R is read. A voice packet including voice data of a sequence number and voice data of a sequence number before the latest one. After step S2705, the wireless base station 20 moves the process to step S2707. Make them carry out the procedure.

[0090] However, if the size of the voice data of the sequence number before the latest one exceeds the playback buffer of the wireless terminal 30, If the buffer size of the playback buffer 340 is larger than the buffer size of the playback buffer 340, Therefore, the transmission data creation unit 27 cannot reproduce the voice data that exceeds the limit. The size of the voice data of the sequence number before the new one is the size of the playback buffer 340 of the wireless terminal 30. If it is less than the buffer size, the audio data includes all the audio data of the sequence numbers before the latest one. Create a voice packet.

[0091] The transmission data creation unit 27 determines whether the size of the voice data of the sequence number before the latest one is equal to the size of the voice data of the wireless terminal. If the buffer size of the playback buffer 340 at the end of the Create a voice packet containing voice data that is equal to or smaller than the buffer size. The generation unit 27 selects the audio data with the newer sequence number and writes it to the playback buffer 340. It is sufficient to create voice packets that are smaller than the buffer size.

[0092] The transmission data creation unit 27 executes the process of step S2705, The interruption of the voice can be reduced. The connected wireless terminal 30 (third wireless terminal) is provided corresponding to the third wireless terminal. At least one ring buffer 240R (third ring buffer) is written to the ring buffer 240R. The third wireless terminal can receive a part of the voice data. The voice data that could not be received during the process of switching to the second wireless base station is stored in the playback buffer. The received data is within the buffer size of the audio device 340 and can be received as valid audio data. .

[0093] If it is not the first transmission in step S2704 (NO), the transmission data creation unit 27 In 2706, the latest system pointed to by the read index stored in the ring buffer 240R is read. The wireless base station 20 creates a voice packet including voice data of the sequence number. Following S2706, the process proceeds to step S2707.

[0094] In step S2707, the transmission unit 28 transmits the voice packet generated in step S2705 or S2706. The wireless terminal 30 then transmits the notification to the wireless terminal 30, and the process proceeds to step S2708 in FIG. 27B.

[0095] On the other hand, if the number of unsent data is not 1 or more in step S2703 (NO), the unsent voice data This means that there is no data, and the wireless base station 20 proceeds to step S2708 in FIG. 27B. Make them carry out the procedure.

[0096] In FIG. 27B, the buffer management unit 24 reads the read index in step S2708. In step S2709, the buffer management unit 24 decrements the number of unsent data by 1. This message updates the number of unsent data items.

[0097] In step S2710, the buffer management unit 24 checks whether the number of unsent data is equal to or less than 0. If the number of unsent data is equal to or less than 0 (YES), the buffer management unit 24 proceeds to step S At 2711, the sequence number of the ring buffer 240R pointed to by the read index is cleared. If the number of unsent data is not equal to or less than 0 (NO), the process proceeds to step S2712. The buffer management unit 24 moves the process to step S2712. In step S2712, the number of terminals to which the data has not been transmitted is decremented by 1 to update the number of terminals to which the data has not been transmitted. Return to step S2701 in 7A.

[0098] In this way, the buffer management unit 24 determines in step S2703 that the number of unsent data is 1 or more. When the read index and the number of unsent data are not received, the read index and the number of unsent data are updated, and the sequence number is cleared. As a result, the wireless base station 20 receives the multicast audio packets transmitted from the center device 10. Even if a packet is lost, the data transmitted from the wireless base station 20 to the wireless terminal 30 and other This allows synchronization with the data that the wireless base station 20 transmits to the wireless terminal 30.

[0099] In step S2701 of FIG. 27A, if the number of terminals to which data has not yet been transmitted is not 1 or more (NO), the buffer In step S2713 of FIG. 27C, the management unit 24 determines whether the number of unconnected terminals is 1 or more. The number of unconnected terminals is the number of wireless terminals 30 that are not connected to the wireless base station 20.

[0100] If the number of unconnected terminals is 1 or more in step S2713 (YES), the buffer management unit 24 In step S2714, an unconnected terminal is selected, and then in step S2715, the selected unconnected terminal is The buffer management unit 24 updates the value of the read index of the last ring buffer. In step S2716, the number of unsent data is decremented by 1 to update the number of unsent data.

[0101] In step S2717, the buffer management unit 24 checks whether the number of unsent data is equal to or less than 0. If the number of unsent data is equal to or less than 0 (YES), the buffer management unit 24 proceeds to step S In 2718, the sequence number of the ring buffer 240R pointed to by the read index is cleared. If the number of unsent data is not equal to or less than 0 (NO), the process proceeds to step S2719. The buffer management unit 24 moves the process to step S2719. At step S2719, the number of unconnected terminals is decremented by 1, the number of unconnected terminals is updated, and the process returns to step S2719. Return to step S2713.

[0102] When the number of unconnected terminals is 1 or more in step S2713, the buffer management unit 24 The index and the number of unsent data are updated, and the sequence number is cleared. The data that the wireless base station 20 transmits to the wireless terminal 30 and the data that another wireless base station 20 transmits to another wireless base station It is possible to synchronize data transmitted to a wireless terminal 30 connected to the wireless terminal 20.

[0103] If the number of unconnected terminals is not 1 or more in step S2713 (NO), the buffer management unit 24 End the process.

[0104] Using the sequence diagram shown in FIG. 28, the wireless base station 20 to be connected by roaming is switched. The method by which the changed wireless terminal 30 obtains the IP address of the newly connected wireless base station 20 will be described. FIG. 28 illustrates a case where the wireless base station 20 to which the wireless terminal 30A is connected is wirelessly transmitted from the wireless base station 20A. 13 shows a sequence diagram when switching to the radio base station 20B.

[0105] The wireless base stations 20A and 20B have second reference timings AT281, AT282, and AT 283... transmits voice packets to the center device 10 and the wireless terminal 30. In step S281, the wireless terminal 30A transmits voice data to the wireless terminal 30A. In step S282, the wireless terminal 30A transmits the voice data to the wireless base station 20A. A disconnects the connection with the wireless base station 20A through the disconnection process in step S283.

[0106] The wireless terminal 30A connects to the wireless base station 20B through the connection process in step S284. In step S285, the wireless base station 20B transmits the voice data to the wireless terminal 30A. The wireless terminal 30A receives the voice data transmitted from the wireless base station 20B. The IP address, communication ID, and delay time of the wireless base station 20B are obtained. The address can be obtained from the IP header of the IP packet.

[0107] The wireless terminal 30A receives the IP address, communication ID, and directory number of the wireless base station 20B. Step S28, which is the transmission timing assigned to the wireless terminal 30A, is performed using the time At 6, the voice data is transmitted to the wireless base station 20B.

[0108] As described above, according to the wireless communication system of the present embodiment, the communication standard of the wireless LAN is This configuration uses a 100-MHz 100-GHz band, and even if the wireless base station to which the wireless terminal is connected is switched, the sound can be heard without any problems. Voice data can be received.

[0109] The present invention is not limited to the above-described embodiment, and any other modifications and variations are possible without departing from the gist of the present invention. Various modifications are possible within a reasonable range. [Explanation of symbols]

[0110] 10 Center device 20,20A,20B,20C Wireless base station 30, 30A, 30B, 30C, 30D Wireless terminal 11,21,31 Receiver 12,22 Received data processing section 13 Base station management department 14 Audio data processing section 15,25 Wireless Terminal Management Department 16,26,35 Transmission cycle management section 17, 27, 36 Transmission data creation section 18,28,37 Transmitter 23,33 Synchronization management section 24,34 Buffer Management Unit 130 Base Station Management Table 150 Terminal Information Table 240 buffers 240R Ring Buffer 250 Wireless terminal information table 340 Playback Buffer

Claims

1. A center device; a plurality of radio base stations connected to the center device; One or more wireless devices wirelessly connected to each of the plurality of wireless base stations A line terminal, Equipped with The center device receives voice data and a voice data for each wireless terminal to which the voice data is to be transmitted. A voice packet including a plurality of pairs of a sequence number indicating the order of voice data to be transmitted is Transmit to all wireless base stations, Each wireless base station The first wireless terminal connected to the own station and the second wireless terminal not connected to the own station are included. a ring buffer provided for each wireless terminal including the The voice data contained in the received voice packet is sent to the wireless Write to the area specified by the write index in the ring buffer provided for the terminal. and a read index of a ring buffer provided corresponding to the first wireless terminal. a buffer management unit that reads the audio data written in the area specified by the address; have Wireless communication system.

2. A method for controlling a wireless communication system by using a computer There was, The center device transmits voice data and a voice data to each wireless terminal to which the voice data is to be transmitted. The center device transmits a voice packet including a plurality of pairs of a sequence number indicating the order of the voice data. transmitting the signal to all of a plurality of wireless base stations connected to the device; Each wireless base station The first wireless terminal connected to the own station and the second wireless terminal not connected to the own station are included. a ring buffer provided for each wireless terminal including the The voice data contained in the received voice packet is sent to the wireless Write to the area specified by the write index in the ring buffer provided for the terminal. and a read index of a ring buffer provided corresponding to the first wireless terminal. reading out the voice data written in the area specified by the address; Includes A method for controlling a wireless communication system.

3. A control program for a wireless communication system that controls the operation of the wireless communication system by a computer Ram, The center device transmits voice data and a voice data to each wireless terminal to which the voice data is to be transmitted. The center device transmits a voice packet including a plurality of pairs of a sequence number indicating the order of the voice data. transmitting the signal to all of a plurality of wireless base stations connected to the device; Each wireless base station The first wireless terminal connected to the own station and the second wireless terminal not connected to the own station are included. a ring buffer provided for each wireless terminal including the The voice data contained in the received voice packet is sent to the wireless Write to the area specified by the write index in the ring buffer provided for the terminal. and a read index of a ring buffer provided corresponding to the first wireless terminal. reading out the voice data written in the area specified by the address; Includes A control program for a wireless communication system.

Images