JP5028784B2 - Wireless LAN telephone system, wireless LAN telephone system base unit, wireless LAN telephone system slave unit, wireless LAN telephone communication method, wireless LAN telephone communication program, and recording medium - Google Patents

Description

  The present invention relates to a cordless telephone system using a wireless LAN, and more particularly to a wireless LAN telephone system that transmits and receives voice as voice packets between a parent device and a child device.

In recent years, IP telephones using VoIP technology have become widespread. IP phones packetize voice and send and receive voices over the Internet and dedicated networks, so call costs are low, and major providers offer services in various regions, so recently not only companies It has been used in many homes. Recently, there has also been a movement to make IP telephones cordless. For example, a product has been announced in which the parent device terminates the IP telephone protocol, and the parent device transmits the voice to the child device using a conventional cordless telephone system. In addition, the IP phone protocol is not terminated at the master unit, but can be terminated at the slave unit, and the slave unit can be brought to a public wireless access point such as a hotspot to make a cheap call. A cordless telephone using a wireless LAN has also been proposed (see, for example, Patent Document 1).
JP 2002-247647 A

  In the IP telephone system having such a configuration, it is known that voice packet delay greatly affects the quality of a call. In particular, when the amount of delay is large, a phenomenon occurs in which the partner speaks before the voice of the speaker reaches the partner. In general, when the one-way delay exceeds 150 ms, such a phenomenon occurs, and the conversation becomes confused or the user feels uncomfortable.

  In many cases, the wireless LAN is used not only for voice communication but also for data communication. Therefore, it is necessary to consider that the call is not interrupted or that the voice is delayed more than necessary even during data communication. Therefore, in the transmission / reception of voice data in a wireless LAN, the TDM system is often used in order to secure a voice communication band for each terminal. One example is HCCA proposed in IEEE 802.11e. In this method, a time slot is assigned to each terminal accommodated in an access point, and each terminal transmits and receives audio data within the time slot assigned to itself. In this way, voice is preferentially transmitted and received using TDM, so that sound is not interrupted or delay is not increased even when data communication is performed.

  However, in this method, since transmission is performed in a predetermined time slot, even if voice data is generated, transmission is awaited until the next time slot comes. In addition, the time slot interval (hereinafter referred to as a transmission interval, usually 10.24 ms or 20.48 ms is used) and the generation period of audio data (hereinafter referred to as a codec interval, usually 10 ms, 20 ms, 30 ms). It is technically difficult to perfectly match the data), and under worst conditions, the voice data is delayed by becoming "waiting for transmission" for a time equal to the transmission interval after the voice data is generated. It will be. In a wireless LAN telephone, the delay can be kept within an allowable range by reducing the codec interval and the transmission interval as well.

  From the above, even when voice communication and data communication are performed simultaneously on the wireless LAN, in order to perform communication so that the delay of the voice is within the allowable range, the voice is packetized in units of 10 ms. Therefore, it is desirable to communicate at a wireless LAN time slot interval of 10.24 ms.

  However, on the other hand, since the amount of data of the voice packet is small, it is known that unnecessary overhead occurs when the packet is converted into a radio frame. For example, in a wireless LAN cordless telephone system with a codec interval of 10 ms, 8 bits / 8 kHz sampling, 80 bytes per packet with no compression, and using the frame format proposed by IEEE 802.11b, voice data It only accounts for about 25%. The remaining 75% is the preamble and header of each layer protocol, and it can be seen that it is very wasteful if voice packets with a small amount of data are transmitted as radio frames (see FIG. 17). Under such circumstances, data communication is compressed by voice data, and traffic is severely restricted. Data communication takes time during a voice call, and the number of simultaneous calls per access point is severe. It is restricted.

  For this reason, at present, there is a strong demand for cordless telephone systems that use a wireless LAN, which suppresses the delay within an allowable range and does not consume a communication band more than necessary.

  The present invention has been made in view of the above-described problems of the prior art, and can reduce the audio delay by reducing the overhead of the radio frame, and can further reduce the delay per access point. The number of simultaneous calls can be increased, and further, when performing data communication during a call, a wireless LAN telephone system, a wireless LAN telephone system parent device, a wireless LAN capable of taking a large bandwidth available for data communication An object of the present invention is to provide a telephone system handset, a wireless LAN telephone communication method, a wireless LAN telephone communication program, and a recording medium.

In order to solve the above-described problems, the wireless LAN telephone communication method of the present invention is configured such that, on the transmission side, the audio codec period, audio codec delay × 2, codec waiting time, transmission waiting time, The transmission waiting allowable time, which is a value obtained by subtracting the network delay amount specified in advance, is calculated, and a plurality of voice packets are converted into at least one of LLC, IP, UDP, and RTP within the range of the transmission waiting allowable time . analyzes the transmission upper protocol header, in one frame of intersection based on the analysis result is omitted, as well as collectively transmitted, the receiving side, restored multiple voice packets into one frame To divide.

In addition, the wireless LAN telephone system slave of the present invention has a voice codec period, a voice codec delay × 2, a codec waiting time, a transmission waiting time, and a network delay amount specified in advance, based on a voice delay allowable time. A transmission waiting allowable time calculation unit that calculates a transmission waiting allowable time that is a value obtained by subtracting the value, a payload integration unit that generates transmission data by combining voice packets input within the transmission waiting time into one frame, and a voice packet When the upper protocol analysis unit that analyzes at least one upper protocol header of LLC, IP, UDP, and RTP and whether or not the received data was originally one voice packet are integrated. to, have a decomposing payload division unit the received data to a plurality of voice packets, the upper pro Coll analyzer analyzes the higher protocol header of a voice packet, the payload integration section based on the analysis result by the higher protocol analysis section, into one frame omitted intersection.

  In addition, the wireless LAN telephone system base unit of the present invention has a wired-wireless bridge unit that replaces a header for switching between wireless frames and wired frames.

  According to the present invention, it is possible to reduce the overhead of radio frame generation and reduce the delay of voice, further increase the number of simultaneous calls per access point, and further, data during a call. When communication is performed, a bandwidth that can be used for data communication can be increased.

In the wireless LAN telephone communication method according to the first aspect of the present invention, in a telephone system using a wireless LAN, on the transmission side, a voice codec period, a voice codec delay × 2, a codec waiting time is calculated from a voice delay allowable time. The transmission waiting time is calculated by subtracting the transmission waiting time and the delay amount of the network designated in advance, and a plurality of voice packets are converted into LLC, IP, UDP within the range of the transmission waiting time. , Analyzing at least one transmission upper protocol header of RTP , and collectively transmitting to one frame in which the common part is omitted based on the analysis result . Divide the voice packet as it was. With this configuration, there is an effect that the overhead in the case of radio frame conversion is reduced and the audio delay is reduced.

  The wireless LAN telephone communication method according to a second aspect of the present invention is the wireless LAN telephone communication method according to the first aspect, wherein QoS is ensured when performing communication between the transmitting side and the receiving side, and voice is transmitted by the TDM method. Communicate. With this configuration, overhead during radio frame conversion is reduced, voice delay is reduced, the number of simultaneous calls per access point is increased, and data is transmitted during data communication during a call. The bandwidth that can be used for communication is increased.

A wireless LAN telephone communication method according to a third aspect of the present invention is the wireless LAN telephone communication method according to the first or second aspect , wherein, on the transmitting side, the error rate of the wireless communication is below a predetermined threshold value. In addition, a plurality of voice packets are transmitted together as one, and when the error rate of wireless communication exceeds a predetermined threshold, it is transmitted without being combined into one frame. With this configuration, when the error rate is high, the radio frames are not combined into one, so the radio frame is not lengthened and remains divided short, and the error occurrence rate decreases because the length of the radio frame is short, When an error occurs, a radio frame that has been divided into short frames is retransmitted, so that the efficiency is higher than when a long radio frame is retransmitted.

The wireless LAN telephone communication program of the fourth invention of the present invention describes the procedure of the wireless LAN telephone communication method of any one of the first to third inventions. With this configuration, for example, the wireless LAN telephone communication method according to any one of the first to third aspects of the invention is realized in a general-purpose computer such as a personal computer.

The storage medium of the fifth invention of the present invention records the wireless LAN telephone communication program of the fourth invention. With this configuration, the wireless LAN telephone communication program of the fourth invention can be ported to a general-purpose computer such as a personal computer.

A wireless LAN telephone system child device according to a sixth aspect of the present invention is a child device of a wireless LAN telephone system that packetizes and transmits voice data using a wireless LAN, and includes a voice delay allowable time, a voice codec period. A transmission waiting time calculation unit for calculating a transmission waiting allowable time based on a speech codec delay × 2, a codec waiting time, a transmission waiting time, and a network delay amount specified in advance; A payload integration unit that generates transmission data by combining input voice packets into one frame, an upper protocol analysis unit that analyzes at least one upper protocol header of LLC, IP, UDP, and RTP of the voice packet, and received data Is originally a single voice packet, and if multiple voice packets are combined, Shin data have a payload division part for decomposing into a plurality of voice packets, wherein the upper protocol analysis section analyzes the higher protocol header of a voice packet, the payload integration unit, the analysis result by the upper protocol analyzer Based on this, the frames are combined into one frame in which common parts are omitted. With this configuration, the communication with the base unit has the effects of reducing the overhead of radio frame conversion and reducing the audio delay.

A wireless LAN telephone system slave unit according to a seventh aspect of the present invention is the wireless LAN telephone system slave unit according to the sixth aspect of the invention, further comprising a time slot management unit for managing time slots, and wireless communication with the master unit In TDM. With this configuration, overhead during radio frame conversion is reduced, voice delay is reduced, the number of simultaneous calls per access point is increased, and data is transmitted during data communication during a call. The bandwidth that can be used for communication is increased.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a functional block diagram showing a handset of the wireless LAN telephone system according to Embodiment 1 of the present invention. In FIG. 1, the subunit | mobile_unit 300 has a function structure shown to 101-120. Reference numeral 101 denotes an operation unit for designating a call destination, instructing a call when receiving a call, and instructing an end of call. Reference numeral 102 denotes a voice input unit for inputting voice. Reference numeral 103 denotes an audio output unit for outputting audio. Reference numeral 104 denotes a reception buffer for accumulating data extracted from the received radio frame. Reference numeral 105 denotes a transmission buffer for wireless transmission that accumulates data to be wirelessly transmitted. Reference numeral 107 denotes a wireless communication unit that converts the data stored in the transmission buffer 105 into a wireless frame and transmits the data, receives the wireless frame, and stores the contents of the frame in the reception buffer 104. Reference numeral 108 denotes an RTC for measuring the passage of time. Reference numeral 109 denotes a parameter storage unit that stores a voice delay allowable time, a voice codec period, a voice codec delay, and a network delay amount designated in advance.

  In addition, 110 performs A / D conversion on the voice input from the voice input unit 102, converts (encodes) the voice into a voice packet using a predetermined algorithm, and decodes the voice data using a predetermined algorithm. A codec unit that performs D / A conversion and outputs the result to the audio output unit 103. Reference numeral 111 denotes a transmission packet queue that stores a voice packet encoded by the codec unit 110 in a FIFO manner together with the time when encoding is completed, that is, the transmission request reception time. A payload integration unit 112 collects voice packets input to the transmission packet queue 111 within a transmission waiting time into one frame and writes them into the transmission buffer. Reference numeral 113 denotes a reception packet queue that disassembles data received as a radio frame into voice packets and stores them in a FIFO manner.

  Further, 114 determines whether or not the content stored in the reception buffer 104 was originally one voice packet. If a plurality of voice packets are integrated, the contents are separated into a plurality of voice packets, and the received packet queue. This is a payload division unit that writes data to 113 using a FIFO method. 115 is a value of the RTC 108 with reference to a voice delay allowable time, a radio frame service period, a voice codec period, a voice codec delay, and a predetermined network delay amount stored in the parameter storage unit 109. Is a transmission waiting time calculation unit that compares the transmission request reception time with the transmission request reception time. 116 is a call control unit that controls outgoing / incoming calls, connection / disconnection of calls, and dial tone, busy tone, ringer, ring back tone according to the state of each call to the voice output unit 103. is there.

  Reference numeral 117 denotes a protocol processing unit that processes call setting and cancellation and voice packet transmission / reception during a call according to a designated protocol. Reference numeral 118 denotes an upper protocol analysis unit that analyzes the upper protocol. Reference numeral 119 denotes an error rate determination unit that calculates an error rate in wireless communication and determines whether the error rate is lower than a predetermined error rate. Reference numeral 120 denotes a TS simple (time slot) management unit that manages a TDM time slot designated by the parent device. A control unit 130 controls the whole.

  FIG. 2 is a device block diagram showing the configuration of the wireless LAN telephone system slave unit according to the first embodiment of the present invention. In FIG. 2, the slave unit 300 has a hardware configuration indicated by 201 to 212 below. 201 is a central processing unit (hereinafter abbreviated as CPU), 202 is ROM, 203 is RAM, 204 is RTC, 205 is baseband, 206 is RF, 207 is A / D, 208 is , Microphone 209, D / A, 210, speaker, 211, keyboard, 212, codec.

  The relationship with the functional configuration of FIG. 1 will be described. The operation unit 101 includes a keyboard 211. The voice input unit 102 includes 208 microphones. The audio output unit 103 includes 210 speakers.

  Further, 104 reception buffers, 105 transmission buffers, 109 parameter storage units, 111 transmission packet queues, and 113 reception packet queues are configured by 203 RAMs. The wireless communication unit 107 includes a baseband unit 205 and an RF 206. 108 RTCs are composed of 204 RTCs. The codec unit 110 includes 212 codecs, 207 A / D, and 209 D / A.

  Also, 112 payload integration unit, 114 payload division unit, 115 transmission waiting time calculation unit, 116 call control unit, 117 protocol processing unit, 118 upper protocol analysis unit, 119 error rate determination unit, 120 The TS management unit and the control unit of 130 refer to the data stored in the ROM of 202 by the CPU of 201 and the data stored in the ROM of 202 or the RAM of 203. It is configured by executing while referring to or changing stored data.

  FIG. 3 is a functional block diagram showing the configuration of the wireless LAN telephone system base unit according to Embodiment 1 of the present invention. In FIG. 3, base unit 400 has a functional configuration indicated by 104 to 122. Reference numeral 104 denotes a reception buffer for accumulating data extracted from the received radio frame. Reference numeral 105 denotes a transmission buffer that accumulates data for wireless transmission. Reference numeral 106 denotes a LAN communication unit for connecting to a wired network. Reference numeral 107 denotes a wireless communication unit that converts the data stored in the transmission buffer 105 into a wireless frame and transmits the data, receives the wireless frame, and stores the contents of the frame in the reception buffer 104. Reference numeral 108 denotes an RTC for measuring the passage of time.

  Reference numeral 111 denotes a transmission packet queue that is stored in the FIFO method together with the transmission request reception time so that the later-described wired-wireless bridge unit 121 converts the frame from the LAN side determined to be relayed into a wireless frame and transmits it. is there. A payload integration unit 112 collects voice packets input to the transmission packet queue 111 within a transmission waiting time into one frame and writes them into the transmission buffer. Reference numeral 113 denotes a reception packet queue that disassembles data received as a radio frame into voice packets and stores them in a FIFO manner. 114 determines whether or not the content stored in the reception buffer 104 was originally one voice packet. When a plurality of voice packets are integrated, the contents are separated into a plurality of voice packets and stored in the reception packet queue 113. This is a payload division unit that writes in the FIFO method.

  Further, reference numeral 118 denotes an upper protocol analyzer that analyzes the upper protocol. Reference numeral 119 denotes an error rate determination unit that calculates an error rate in wireless communication and determines whether the error rate is lower than a predetermined error rate. Reference numeral 121 denotes a wired-wireless bridge that relays a frame between wired and wireless if necessary and discards the frame. Reference numeral 122 denotes a QoS management unit that assigns a TDM time slot to each slave unit. A control unit 130 controls the whole.

  FIG. 4 is an apparatus block diagram showing the configuration of the wireless LAN telephone system base unit according to Embodiment 1 of the present invention. In FIG. 4, base unit 400 has a hardware configuration indicated by 201 to 213 below. 201 is a CPU, 202 is a ROM, 203 is a RAM, 205 is a baseband unit, 206 is an RF, and 213 is a network I / F.

  The relationship with the functional configuration of FIG. 3 will be described. The 104 reception buffer, 105 transmission buffer, 111 transmission packet queue, and 113 reception packet queue are configured by 203 RAMs. The wireless communication unit 107 includes a baseband unit 205 and an RF 206. 108 RTCs are composed of 204 RTCs. The LAN communication unit 106 includes a network interface 213.

  112 payload integration unit, 114 payload division unit, 118 upper protocol analysis unit, 119 error rate determination unit, 121 wired-wireless bridge unit, 122 QoS management unit, and 130 control unit, The program stored in the ROM 202 by the CPU 201 is referred to the data stored in the ROM 202, the data stored in the RAM 203 is referred to, or changed. It is configured by executing while.

  Next, the overall configuration of the wireless LAN telephone system of the present embodiment will be described. FIG. 5 is a diagram showing the overall configuration of the wireless LAN telephone system according to Embodiment 1 of the present invention. As shown in the figure, the child device A300 is under the control of the parent device A400, and similarly, the child device B300 is under the management of the parent device B400. Base unit A 400 and base unit B 400 are each connected to the Internet. The base unit A400 and the base unit B400 have a bridging function, and relay a wireless frame from the slave unit as an Ethernet (registered trademark) frame to the Internet side using a LAN communication unit (wired). An Ethernet (registered trademark) frame from the Internet side is relayed as a wireless frame to the slave unit.

The operations of the master unit and the slave unit of the wireless LAN telephone system configured as described above will be described with reference to a sequence chart showing an outline of the operation of the wireless LAN telephone system according to the first embodiment of the present invention shown in FIG. The operation described below refers to a protocol called SIP that is often used in VoIP in recent years. However, in order not to make the description more complicated than necessary, the processing is somewhat simplified. In addition, here, explanation will be given with an emphasis on the cooperation between the parent device and the child device. Details of “encoding” and “decoding” of the slave unit, “bridge processing” of the master unit, and “wireless transmission” and “wireless reception” of the master unit and the slave unit will be described later. In this description, it is assumed that handset 300 is initially in a standby state.
[Step E01]
First, the user of handset A300 uses the operation unit 101 of handset A300 to specify a call destination. Here, it is assumed that the user inputs 050-1001-1234 as the call destination number from the operation unit 101 and instructs the call.
[Step M02]
The control unit 130 receives the call destination number input from the operation unit 101 and requests the call control unit 116 to set a call to the designated call destination number. The call control unit 116 creates an “INVITE” message and requests the protocol processing unit 117 to transmit to the handset B 300 in order to notify the handset B 300 of the “call connection request”. The protocol processing unit 117 transmits data indicating “INVITE” to the base unit A 400 through the wireless communication unit 107 (details will be described later as “slave unit transmission process”). Base unit A 400 converts the received wireless frame into a wired Ethernet (registered trademark) frame and transmits it to the Internet (details will be described later as “base unit bridge processing”). The Ethernet (registered trademark) frame transmitted from the base unit A400 arrives at the base unit B400 through the Internet (not shown in the figure). Base unit B 400 relays the received Ethernet (registered trademark) frame, converts it into a radio frame, and transmits it to hand unit B 300 (details will be described later as “base unit bridge processing”). The slave unit B300 receives the radio frame transmitted from the master unit B400, and notifies the call control unit 116 of the “INVITE” message via the radio communication unit 107 and the protocol processing unit 117 (for details, refer to “Slave unit reception process”). As described below). As a result, handset B300 is called.
[Step E03]
In handset B300, call control unit 116 requests codec unit 110 to play a ringer (ringing tone). As a result, the codec unit 110 outputs the voice stored in the voice output unit 103 as a ring tone.
[Step M04]
In the slave unit B300, the call control unit 116 creates a “RINGING” message and requests the protocol processing unit 117 to transmit to the slave unit A300 in order to notify the slave unit A300 that “incoming call has been accepted”. The protocol processing unit 117 transmits data meaning “RINGING” to the parent device B 400 via the wireless communication unit 107. This data is converted from a wireless frame to an Ethernet (registered trademark) frame by the base unit B400, and reaches the base unit A400 through the Internet. Further, base unit A 400 relays the received Ethernet (registered trademark) frame and transmits it to base unit A 300 as a radio frame.
[Step E05]
In the handset A300, the call control unit 116 receives the “RINGING” message via the wireless communication unit 107 and the protocol processing unit 117, and knows that the call destination has accepted the incoming call. The call control unit 116 requests the codec unit 110 to output a ring back tone (ringing tone, hereinafter abbreviated as RBT). As a result, the codec unit 110 outputs the RBT to the audio output unit 103.
[Step E06]
In handset B300, when the user hears the ringer and notices that he / she is receiving a call, he / she operates operation unit 101 to instruct a call. As a result, in handset B 300, control unit 130 receives the message “instructed to talk” from operation unit 101, and requests call control unit 116 to “connect the call”.
[Step M07]
In the slave unit B300, the call control unit 116 requests the TS management unit 120 to secure QoS. The TS management unit 120 transmits a “QoS request” to the parent device B 400 via the protocol processing unit 117 and the wireless communication unit 107. As a result, in the base unit B 400, the QoS management unit 122 receives the “QoS request” via the wireless communication unit 107 and the protocol processing unit 117, and the TDM time slot (specifically, Service start time and service cycle) are determined and transmitted to the slave unit B 300 via the protocol processing unit 117 and the wireless communication unit 107. In the slave device B300, the wireless communication unit 107 receives "designation of time slot" and notifies the TS management unit 120 via the protocol processing unit 117. As a result, the TS management unit 120 stores the TDM service cycle and the start time, and performs subsequent communication in the time slot designated by the base unit B400. The TS management unit 120 notifies the call control unit 116 of the completion of QoS reservation.

Further, the call control unit 116 activates an encoding task (described later) and a decoding task (described later). Thereafter, until the call disconnection is instructed, the codec unit 110 encodes the voice received from the voice input unit 102, and requests the protocol processing unit 117 to transmit the result as a voice packet to the child device A300. Then, as described above, the voice packet reaches the child device A300 via the parent device B400 and the parent device A400. Also, in the slave unit B300, the voice packet from the slave unit A300 received by the codec unit 110 via the wireless communication unit 107 and the protocol processing unit 117 is decoded, and the result is output to the voice output unit 103. Become.
[Step M08]
In the slave unit B300, the call control unit 116 creates a “CONNECT-OK” message to notify the slave unit A300 that “the user has responded to the incoming call”, and transmits the message to the slave unit A300. Request to 117. The protocol processing unit 117 transmits data indicating “CONNECT-OK” to the parent device B 400 via the wireless communication unit 107. As a result, the base unit B400 converts the radio frame received from the handset B300 into an Ethernet (registered trademark) frame and relays it, and the Ethernet (registered trademark) frame reaches the base unit A400 through the Internet. Base unit A400 converts the received Ethernet (registered trademark) frame into a radio frame, relays it, and transmits it to handset A300. In handset A300, call control unit 116 receives “CONNECT-OK” via wireless communication unit 107 and protocol processing unit 117, and requests codec unit 110 to stop the RBT. Thereby, the codec unit stops the RBT.
[Step M09]
In the child device A300, the same processing as in M07 is performed. I've omitted the details as I already explained.
[Step E10]
Thereafter, a communication path in which full-duplex QoS is guaranteed is ensured, and a call can be made. Here, it is assumed that the communication band of the Internet is sufficiently wide and the delay is about several tens of ms. That is, it is assumed that the bottleneck of communication between the child device A300 and the child device B300 is between the child device and the parent device.
[Step M11]
During a call, the voice of the user of the slave unit A300 is input to the voice input unit 102 of the slave unit A300, encoded by the codec unit 110 as described above, and transmitted to the slave unit B300 by the protocol processing unit 117 as a voice packet. . At this time, between the child device A300 and the parent device A400, the voice packet is transmitted in the service cycle managed by the TS management unit 120. In the slave unit B300, the codec unit 110 receives the voice packet via the wireless communication unit 107 and the protocol processing unit 117, decodes this, and outputs the result to the voice output unit 103 of the slave unit B300. The process in which the user's voice on the handset B300 side reaches the handset A300 is a process that is exactly symmetric to the above-described process, and therefore details are omitted.
[Step E12]
In slave unit B300, the user instructs call disconnection from operation unit 101. As a result, the control unit 130 receives a call disconnection instruction from the operation unit 101 and requests the call control unit 116 to disconnect the call. The call control unit 116 stops the encoding task and the decoding task. As a result, the codec unit 110 stops the codec. Thereafter, even if a voice packet is received, it is discarded, and the voice input is not encoded.
[Step M13]
In the slave device B300, the call control unit 116 requests the TS management unit 120 to release QoS. The TS management unit 120 requests the master device B 400 to release QoS via the protocol processing unit 117 and the wireless communication unit 107. In base unit B 400, wireless communication unit 107 receives a “QoS release” request and notifies QoS management unit 122. The QoS management unit 122 releases the TDM time slot previously assigned to the slave unit B300 and prepares it to be assigned if requested by another slave unit. When the QoS communication is completed, the wireless communication unit 107 of the parent device B 400 transmits a wireless frame that notifies the child device B 300 to that effect. When receiving the wireless frame, slave unit B 300 notifies TS management unit 120 via protocol processing unit 117. The TS management unit 120 releases QoS and notifies the call control unit 116 to that effect.
[Step M14]
In the slave unit B300, the call control unit 116 creates a “BYE” message and requests the protocol processing unit 117 to transmit it to the slave unit A300. The protocol processing unit 117 transmits data indicating “BYE” to the parent device B 400 via the wireless communication unit 107. As before, the “BYE” message arrives at the child device A300 via the parent device B400, the Internet, and the parent device A400.
[Step E15]
In handset A 300, call control unit 116 receives the message “BYE” via wireless communication unit 107 and protocol processing unit 117. The call control unit 116 stops the encoding task and the decoding task. As a result, the codec unit 110 stops the codec. Thereafter, even if a voice packet is received, it is discarded, and no encoding is performed for voice input.
[Step M16]
Similar to step M13, the slave unit A300 requests the master unit A400 to release QoS. I've omitted the details as I already explained.
[Step M17]
In the child device A300, the call control unit 116 creates a “BYE-OK” message and requests the protocol processing unit 117 to transmit the message to the child device B300. The protocol processing unit 117 transmits data indicating “BYE-OK” to the parent device A 400 via the wireless communication unit 107. As before, the message “BYE-OK” arrives at the child device B300 via the parent device A400, the Internet, and the parent device B400.
[Step E18]
In the slave unit B, the call control unit 116 receives the “BYE-OK” message via the wireless communication unit 107 and the protocol processing unit 117. Thereafter, the slave unit B300 enters the “standby mode”.

  Next, an outline of the operation of the slave unit of the present embodiment will be described. FIG. 7 is a diagram showing a task configuration of the wireless LAN telephone system slave unit according to the first embodiment of the present invention. In the present embodiment, handset 300 has an encoding task for encoding audio, a protocol processing task for controlling transmission / reception of data according to a protocol, a decoding task for decoding audio, a call control task for performing call setting / connection / disconnection, It is assumed that a wireless transmission task that transmits a voice packet as a wireless frame and a wireless reception task that receives a wireless frame and converts it into a voice packet are operating in parallel. The encoding task, decoding task, and call control task make a transmission request and a reception request to the protocol processing task. After making the reception request, when the protocol processing task receives the requested data, the protocol processing task notifies the requesting task to that effect. In addition, the arrow in a figure has shown the flow of data.

  Next, an outline of the operation of the base unit of the present embodiment will be described. FIG. 8 shows a task configuration of the wireless LAN telephone system base unit according to the first embodiment of the present invention. In the base unit 400, the radio transmission task, the radio reception task, and “the radio frame received by the radio reception task are examined, and it is determined whether to relay the frame between wired and wireless, as in the case of the slave unit. If there is, after converting the frame format, the Ethernet (registered trademark) frame is transmitted through the LAN communication unit 106, and the Ethernet (registered trademark) frame received through the LAN communication unit 106 is examined, and wired and wireless are transmitted. A bridge task is operating in parallel, which determines whether to relay a frame between them, and if necessary, converts the frame format and passes it to the wireless transmission task.

Hereinafter, the operation of each task of the slave unit will be described using a flowchart. First, the encoding task processing will be described with reference to the flowchart of FIG. 9 showing the encoding task operation of the wireless LAN telephone system slave unit according to the first embodiment of the present invention. The encoding task is activated during a call by the call control task. When the call ends, it is stopped by the call control task. The following description is the operation of the encoding task during a call.
[Step S01]
The codec unit 110 receives audio from the audio input unit 102, performs sampling (A / D conversion), and encoding.
[Step S02]
The codec unit 110 refers to the codec interval stored in the parameter storage unit 109 and determines whether or not encoding has been performed for the time specified by the codec interval while comparing with the RTC 108. If the designated time has elapsed, the process proceeds to step S03. Otherwise, the process returns to step S01.
[Step S03]
The codec unit 110 passes the sampled data to the protocol processing unit 117 and requests transmission. Return to step S01.

Next, the decoding task processing will be described with reference to the flowchart of FIG. 10 showing the decoding task operation of the wireless LAN telephone system slave unit according to the first embodiment of the present invention. The decode task is activated during a call by the call control task. When the call ends, it is stopped by the call control task. The following description is the operation of the decoding task during a call.
[Step S101]
The codec unit 110 confirms whether a reception notification is received from the protocol processing unit 117. If a reception notification has been received, the process proceeds to step S102. Otherwise, the process returns to step S101.
[Step S102]
The codec unit 110 receives received data from the protocol processing unit 117.
[Step S103]
The codec unit 110 decodes the received data, D / A converts the result, and outputs the output to the audio output unit 103. Return to step S101.

  Next, the operation of the call control task will be described with reference to the state chart showing the operation of the call control task of the wireless LAN telephone system slave unit according to the first and second embodiments of the present invention shown in FIG.

First, the operation of the call control task will be described from the side of handset A300 with respect to a series of processes in which handset A300 is turned on and the user of handset A300 makes a call, makes a call, and disconnects.
[Step E101]
When power on of slave unit 300 is instructed from operation unit 101, control unit 130 activates a call control task, a protocol processing task, a wireless transmission task, and a wireless reception task. When the call control task is activated, it transitions to a standby state. As a result, incoming and outgoing calls can be made thereafter.
[Step E102]
The user operates the operation unit 101 on the child device A300 to make a call to the child device B300. The control unit 130 of the slave unit A 300 receives the “call” notification from the operation unit 101, receives the call destination number, and requests the call control unit 116 to designate the other party number and make a “call connection” request. The call control unit 116 requests the protocol processing unit 117 to transmit the “INVITE” message to the child device B 300. Slave device B300 receives the “INVITE” message, becomes in-call, and returns a “RINGING” message to slave device A300. The call control unit 116 of the child device A300 receives the “RINGING” message from the child device B300 via the protocol processing unit 117, and transitions to a calling state. The call control unit 116 outputs the RBT to the voice output unit 103 to inform the user that “calling”.
[Step E103]
In cordless handset B300, a ringer (ringing tone) is ringing, and the user notices the ringing tone and accepts the incoming call. As a result, the slave unit B300 secures the QoS with the master unit B400, and after the encode task and the decode task are activated, a “CONNECT-OK” message is transmitted to the slave unit A300. In handset A300, call control unit 116 receives the “CONNECT-OK” message via protocol processing unit 117, and requests TS management unit 120 to ensure QoS. The TS management unit 120 makes a QoS reservation request to the parent device A400, and after the QoS is secured by the parent device A400, the TS (time slot) designated by the parent device A400 is received. The TS management unit 120 notifies the call control unit 116 that QoS reservation has been completed.

As a result, the call control unit 116 activates the above-described encoding task and decoding task, and the codec unit 110 performs A / D conversion and encoding on the subsequent voice from the voice input unit 102 and sends it to the protocol processing unit 117 as a voice packet. hand over. Further, the codec unit 110 decodes and D / A converts the voice packet received by the protocol processing unit 117, and outputs it to the voice output unit 103. Transition during a call.
[Step E109]
When the user of the child device A300 finishes the call, the operation unit 101 of the child device A300 is operated to disconnect the call. The control unit 130 receives a disconnection operation notification from the operation unit 101 and requests the call control unit 116 to perform “call disconnection”. The call control unit 116 stops the encoding task and the decoding task, and requests the TS management unit 120 for “QoS release”. The TS management unit 120 makes a “QoS release” request to the base unit A 400 via the protocol processing unit 117 and the wireless processing unit 107, and is transmitted from the base unit A 400 after QoS is released by the base unit A 400. “QoS release complete” is received via the wireless processing unit 107 and the protocol processing unit 117 and notified to the call control unit 116. As a result, the call control unit 116 requests the protocol processing unit 117 to send a “BYE” message to the child device B 300. The protocol processing unit 117 transmits data indicating a “BYE” message to the parent device A 400 via the wireless processing unit 107 and arrives at the child device B 300 via the Internet and the parent device B 400. Upon receiving the “BYE” message, handset B300 returns “BYE-OK” to handset A300. In handset A300, call control unit 116 receives the "BYE-OK" message via wireless communication unit 107 and protocol processing unit 117. Thereby, it changes to a standby state.
[Step E107]
When a user cancels a call while making a call, the operation unit 101 issues a call cancellation instruction, the control unit 130 receives a call cancellation instruction from the operation unit 101, and issues a call to the call control unit 116. Request cancellation. The call control unit 116 requests the protocol processing unit 117 to transmit a “CANCEL” message to the child device B 300. Handset B300 stops the ringer and sends a "CANCEL-OK" message to handset A300. In the slave unit A300, when the protocol processing unit 117 receives “CANCEL-OK” from the slave unit B300 and notifies the call control unit 116, the call control unit 116 transitions to a standby state.

Next, the operation of the call control task as seen from the handset B 300 side will be described.
[Step E104]
The protocol processing unit 117 receives the “INVITE” message from the child device A 300 and notifies the call control unit 116 of it. The call control unit 116 requests the protocol processing unit 117 to return a “RINGING” message to the child device A 300. The call control unit 116 outputs a ringer to the voice output unit 103 to inform the user that an incoming call has occurred. The call control unit 116 transitions to an incoming call state.
[Step E105]
The user learns that the ringer is receiving a call and operates the operation unit 101 to respond to the incoming call. The control unit 130 receives an incoming response from the operation unit 101 and requests the call control unit 116 for a response. The call control unit 116 requests the QoS management unit 120 to “guarante QoS”. The TS management unit 120 transmits a “QoS reservation request” to the base unit B 400. Master device B 400 receives this, secures QoS, and transmits “QoS secure completion” to slave device B 300. The protocol processing unit 117 receives “QoS reservation completion” and notifies the TS management unit 120 of the TS (time slot). The TS management unit 120 notifies the call control unit 116 of the completion of QoS reservation.

As a result, the call control unit 116 requests the protocol processing unit 117 to transmit a “CONNECT-OK” message to the child device A300. The protocol processing unit 117 transmits a “CONNECT-OK” message to the child device A300. Further, the call control unit 116 stops the ringer output to the audio output unit 103, starts the encoding task and the decoding task, and the audio from the subsequent audio input unit 102 is A / D converted / encoded, and the audio packet To the child device A300, and the voice packet from the child device A300 is decoded and D / A converted and output from the voice output unit 103.
[Step E109]
The protocol processing unit 117 receives the “BYE” message from the child device A 300 and notifies the call control unit 116 of it. The call control unit 116 requests a “QoS release” from the TS management unit 120, and the TS management unit 120 transmits a “QoS release request” to the parent device B 400. Master device B 400 receives this, releases QoS, and returns “QoS release complete” to child device B 300. The protocol processing unit 117 receives this and notifies the TS management unit 120 of it. The TS management unit 120 releases the QoS and notifies the call control unit 116 of the completion of the QoS release. The call control unit 116 stops the encoding task and the decoding task, and transitions to a standby state.

If the user of handset A300 cancels the call during a call, the process proceeds to step E108.
[Step E108]
The protocol processing unit 117 receives the “CANCEL” message and notifies the call control unit 116 of it. The call control unit 116 stops the ringer, requests the protocol processing unit 117 to transmit a “CANCEL-OK” message to the child device A300, and shifts to a standby state.

Next, the operation of the protocol processing task will be described with reference to the flowchart of FIG. 12 showing the operation of the protocol processing task of the wireless LAN telephone system slave unit according to the first and second embodiments of the present invention.
[Step S201]
The protocol processing unit 117 checks whether there is a transmission request from the encode task, the decode task, and the call control task. If there is, the process proceeds to step S202. If not, the process proceeds to step S203.
[Step S202]
The protocol processing unit 117 receives a transmission request, adds a header according to each protocol, and puts it in the transmission packet queue 111. The transmission packet queue 111 is prepared for each destination. Here, the destination is a transmission destination MAC address defined in IEEE 802.11. At this time, the time at which this transmission request is received is written in association with the transmission request with reference to the RTC 108. Proceed to step S201.

Here, a description will be given assuming that an audio packet is received from the encoding task. The protocol processing unit 117 adds an RTP header, UDP header, IP header, and LLC header to the voice packet and determines a destination MAC address (usually, the destination is given by an IP address, and the protocol processing unit 117 (The details are the same as the TCP / IP communication process, and will be omitted.) The protocol processing unit 117 selects a transmission packet queue having a destination MAC address of the voice packet from the transmission packet queue 111 prepared for each MAC address, and puts the voice packet in the transmission packet queue 111. At this time, the RTC 108 is referred to and written in the transmission packet queue as the transmission request reception time. Proceed to step S201.
[Step S203]
The protocol processing unit 117 checks whether data has arrived at the reception packet queue 113. If it has arrived, the process proceeds to step S204; otherwise, the process proceeds to step S201.
[Step S204]
The protocol processing unit 117 extracts received data from the received packet queue 113.
[Step S205]
Check the data destination. If the destination is a decode task, it notifies the decode task, and if it is a call control task, notifies the call control task. Proceed to step S201.

Next, the operation of the wireless transmission task of handset 300 will be described with reference to the flowchart of FIG. 13 showing the operation of the wireless transmission task of the wireless LAN telephone system handset according to the first embodiment of the present invention. The transmission packet queue 111 exists for each destination MAC address, and the wireless transmission task performs the following processing for each transmission packet queue 111. However, in the following description, the operation will be described focusing on one transmission packet queue 111.
[Step S301]
The control unit 130 compares the RTC 108 with the “next transmission time” set in the parameter storage unit 109. If the current time is equal to or exceeds the “next transmission time”, the control unit 130 proceeds to step S302. Otherwise, go to step S301. Here, it is assumed that the value of RTC 108 is 12:33 22.0113 994 and the “next transmission time” is 12:33 22.0113 994.
[Step S302]
The control unit 130 inquires of the TS management unit 120 about the “service period”, refers to the RTC 108, calculates the next transmission time, and updates the “next transmission time”. Here, since the service period is 10.24 ms and the value of the RTC 108 is 12:33 22.0113 994, the next transmission time is therefore 12:33 22.024.234.
[Step S303]
The control unit 130 refers to the transmission packet queue 111 and determines whether the queue is empty. If it is empty, the process proceeds to step S301; otherwise, the process proceeds to step S304.
[Step S304]
The control unit 130 pays attention to the first entry in the transmission packet queue 111.
[Step S305]
The control unit 130 inquires of the error rate determination unit 119 whether the error rate is lower than a preset threshold. The error rate determination unit 119 passes the determination result to the control unit 130. From the received determination result, if the error rate is low, the process proceeds to step S306; otherwise, the process proceeds to step S315. Here, the description will be continued assuming that the error rate is low.
[Step S306]
The control unit 130 requests the transmission waiting allowable time calculation unit 115 to calculate the transmission waiting allowable time. Thereby, the transmission waiting allowable time calculation unit 115 refers to the parameter storage unit 109, the RTC 108, and the transmission request reception time recorded in association with the entry, and calculates a delay allowable time. First, the transmission waiting time is obtained from the RTC 108 and the transmission request reception time. Here, it is assumed that the following values shown in (Expression 1) are obtained.

  Further, it is assumed that (Equation 2) is stored in the parameter storage unit 109 in advance.

  Note that codec delay means that A / D conversion is performed after audio is input, and data encoded by a specified algorithm (in this case, μ-law PCM 8 kHz 8-bit sampling is specified) is output. It is a time until the data frame is received, and it is possible to obtain a voice frame only after collecting this data corresponding to the codec period. In addition, the delay time from when the audio frame is decoded and D / A converted and output as audio is also set to the same value. Although this delay time may be asymmetric depending on the codec algorithm, it will be described here as being symmetric. Furthermore, the codec waiting time is a time for providing a jitter buffer on the receiving side to temporarily store voice packets waiting to be decoded so that the voice is not interrupted even if the arrival of the voice packet fluctuates. It is. The transmission waiting allowable time is calculated by the following equation using (Equation 3).

  FIG. 14 is a diagram showing the breakdown of the voice delay amount of the wireless LAN telephone system according to the first and second embodiments according to the present invention, in which the above formula is illustrated in an easy-to-understand manner.

The allowable transmission waiting time for the entry of interest from the above is 13 ms.
[Step S307]
The control unit 130 determines whether the next transmission is in time. If it is determined that it is in time, the process proceeds to step S309; otherwise, the process proceeds to step S308. Here, the current time is 12:33 22.013 994. In this case, since the transmission waiting allowable time is 13 ms, it is understood that the transmission should be performed by the worst, 12:33 22.026 994. Since the next transmission time is 12:33 22.024 234, it is determined that the next transmission is in time.
[Step S308]
The control unit 130 determines whether the data to be transmitted already exists in the transmission buffer 105 at the current transmission timing. That is, even if it is determined in step S307 that the next transmission is in time, if there is already data to be transmitted to the transmission buffer 105, it is better to transmit the data collectively. That is, when it exists, it progresses to step S309, otherwise, it progresses to step S301. Here, the description will be continued assuming that no data exists in the transmission buffer 105. In this case, the process proceeds to step S301.

Thereafter, it is assumed that the time has elapsed and the time has become 12:33 22.024 234. Here, steps S301 to S306 are executed. Here, it is assumed that two voice packets are enqueued in the transmission packet queue 111 as shown in FIG.
The transmission waiting time is (Equation 4).

Therefore, the transmission waiting allowable time = 3 ms. Since the next transmission time is 12: 33.22 034 474, it is determined in step S307 that entry 1 is not in time for the next transmission, and the process proceeds to step S309.
[Step S309]
The control unit 130 extracts the data of the entry of interest from the transmission packet queue 111.
[Step S310]
The control unit 130 instructs the payload integration unit 112 to merge data. Details will be described later. Data to be transmitted is written in the transmission buffer 105.
[Step S311]
The control unit 130 refers to the transmission packet queue 111 and determines whether there is still an entry. If there is, the process proceeds to step S312, and if not, the process proceeds to step S313. Here, since another entry is enqueued as shown in FIG. 15 which shows the contents of transmission packet queue 111 of the wireless LAN telephone system slave unit according to the first embodiment of the present invention, the process proceeds to step 12.
[Step S312]
The control unit 130 pays attention to the next entry. Proceed to step S305. Here, the control unit 130 pays attention to the entry 2, and further determines whether the entry 2 is in time for the next transmission in step S307. Here, since it is determined that it is in time, the process proceeds to step S308. Next, in step S308, since entry 1 has been written in the transmission buffer 105 earlier, the process proceeds to step S309. In step S309, data is extracted from the transmission packet queue 111, and in step S310, the transmission data is merged. Details of the merge processing will be described later. In this way, voice packets that can be determined to be sent at one time are collected into one radio frame. In step S311, it is determined that all entries in the transmission packet queue 111 have been evaluated, and the process advances to step S313.
[Step S313]
Here, it is assumed that the radio frame is encrypted by an encryption method defined by IEEE 802.11i. The control unit 130 instructs the wireless communication unit 107 to add the CCMP header and the MIC key. As a result, the wireless communication unit 107 calculates the CCMP header and the MIC key according to the encryption algorithm, and adds them to the payload position defined by IEEE802.11i in the transmission buffer 105.
[Step S314]
The control unit 130 instructs the wireless communication unit 107 to transmit the contents of the transmission buffer 105. As a result, the wireless communication unit 107 releases the instructed content as a wireless frame into the air. Proceed to step S301. Here, it is assumed that the preamble and FCS defined in IEEE 802.11 are added by the wireless communication unit 107.

On the other hand, if it is determined in step S305 that the error rate is high, the process proceeds to step S315.
[Step S315]
Processing similar to that in step S309 is performed.
[Step S316]
Processing similar to that in step S310 is performed.
[Step S317]
Processing similar to that in step S313 is performed.
[Step S318]
Processing similar to that in step S314 is performed.
[Step S319]
The control unit 130 refers to the transmission packet queue 111 and determines whether there are still unevaluated entries. If there is, the process proceeds to step S312, and if not, the process proceeds to step S301. In this case, as in the conventional wireless LAN, the voice packet is transmitted as it is as one wireless frame.

Next, details of the merge process will be described with reference to the flowchart of FIG. 16 showing the transmission merge process of the wireless LAN telephone system according to the first embodiment of the present invention. Here, the description will be made assuming that the contents of the entry extracted from the transmission packet queue 111 by the control unit 130 are passed to the payload integration unit 112.
[Step S401]
The payload integration unit 112 determines whether data is written in the transmission buffer 105. If it has been written, the process proceeds to step S407; otherwise, the process proceeds to step S402.
[Step S402]
The payload integration unit 112 writes the MAC header in the transmission buffer 105.
[Step S403]
The payload integration unit 112 passes the contents of the entry to the upper protocol analysis unit 118. Thus, the upper protocol analysis unit 118 recognizes the protocol header of the upper protocol (here, LLC, IP, UDP, RTP) in the packet and stores the header of each layer.
[Step S404]
The payload integration unit 112 calculates the total number of bytes of the received voice packet. Here, LLC header (8 bytes) + IPv6 header (40 bytes) + UDP header (8 bytes) + RTP header (12 bytes) + voice (80 bytes) = 148 bytes.
[Step S405]
The payload integration unit 112 writes the total number of bytes obtained in step S404 as the payload delimiter 1 in the transmission buffer 105. Here, 148 is written.
[Step S406]
The payload integration unit 112 writes the data received as a voice packet in the transmission buffer 105. End the merge process.
[Step S407]
The payload integration unit 112 passes the contents of the entry to the upper protocol analysis unit 118. Thereby, the upper protocol analysis unit 118 recognizes the protocol header of the upper protocol (here, LLC, IP, UDP, RTP) in the packet and compares it with the content stored in step S403. The upper protocol analysis unit 118 passes the result of analyzing the header to the payload integration unit 112. Here, the payload integration unit 112 is informed that the LLC header, IP header, and UDP header are redundant.
[Step S408]
The payload integrating unit 112 calculates the total number of bytes of data to be transmitted if a redundant header is omitted. Here, a total 93 of a 1-byte flag indicating which redundant header is included, a 12-byte RTP header that cannot be omitted, and 80-byte audio data is calculated.
[Step S409]
The payload integration unit 112 writes the value calculated in step S408 in the transmission buffer 105 as a payload delimiter. Here, 93 is written.
[Step S410]
Next, the payload integration unit 112 writes a flag 1 byte indicating which redundant header is in the transmission buffer 105. Here, according to the OSI layer model, the flags represent the second layer, the third layer, the fourth layer, and the fifth to seventh layers with 2 bits each, and 00 is “there was no corresponding header originally” , 01 represents “there was a header but it was omitted because it was redundant” and 10 “it could not be omitted”. Here, since the LLC header, IP header, and UDP header can be omitted, and the RTP header cannot be omitted, the value of the flag is 01011010.
[Step S411]
The payload integration unit 112 writes the header and audio data that could not be omitted to the transmission buffer 105. End the merge process.

  Here, 12 bytes of RTP header and 80 bytes of audio data are subsequently written in the transmission buffer 105. FIG. 17 is a diagram showing a format of a radio frame according to IEEE 802.11. FIG. 18 is a diagram showing a frame format when two voice packets are combined into one radio frame according to the first embodiment of the present invention. First, after the CCMP header is written by the encryption engine built in the wireless communication unit 107 and the MIC key is added, the PLCP preamble, the PLCP header, and the FCS are added when the wireless communication unit 107 generates a wireless frame. . From the comparison between FIG. 17 and FIG. 18, if two voice packets are not originally transmitted in two radio frames but are combined into one radio frame, the frame length is only 25% larger, so the transmission efficiency is greatly improved. I understand that.

Next, the operation of the wireless reception task will be described with reference to the flowchart of FIG. 19 showing the operation of the reception task of the wireless LAN telephone system according to the first embodiment of the present invention. Here, it is assumed that the wireless frame addressed to the local station is received by the wireless communication unit 107, and the content of the frame is written as data in the reception buffer 104 in a state where the encryption is released. That is, it is assumed that the CCMP header and the MIC key are removed. Here, it is assumed that the wireless communication unit ignores the frames other than the wireless frame addressed to the own station. That is, data written to the reception buffer is limited to data destined for the own station.
[Step S501]
The payload dividing unit 114 refers to the reception buffer 104 and determines whether data is received. If received, the process proceeds to step S502; otherwise, the process proceeds to step S501.
[Step S502]
The payload dividing unit 114 extracts data from the reception buffer 104.
[Step S503]
The payload dividing unit 114 takes out the MAC header.
[Step S504]
Payload divider 114 focuses on the first payload.
[Step S505]
The payload dividing unit 114 interprets the next one byte as a delimiter, reads a value, obtains how many bytes the payload is, and cuts out the payload by the number of bytes.
[Step S506]
The payload dividing unit 114 passes the payload obtained in step S505 to the upper protocol analyzing unit 118. As a result, the upper layer protocol analysis unit 118 interprets the headers in the second layer, the third layer, the fourth layer, and the fifth to seventh layers, and notifies the payload division unit 114 of them. Here, it is assumed that it can be interpreted as an LLC header, an IP header, a UDP header, and an RTP header. The upper protocol analysis unit 118 stores a header for each layer.
[Step S507]
The payload dividing unit 114 puts the obtained payload in the reception packet queue 113.
[Step S508]
The payload dividing unit 114 refers to the reception buffer 104 and determines whether all the payloads have been cut out. If all the payloads have been cut out, the process proceeds to step S501. Otherwise, the process proceeds to step S509.
[Step S509]
The payload dividing unit 114 refers to the reception buffer 104 and pays attention to the next payload.
[Step S510]
The payload dividing unit 114 interprets the next one byte in the reception buffer 104 as a delimiter, reads the value, obtains the number of the payload of interest, and cuts it out as many as the number of bytes.
[Step S511]
The payload dividing unit 114 interprets the next 1 byte as an omission flag and determines which layer's header is omitted. Further, for the omitted header, the higher-level protocol analysis unit 118 is instructed to restore the header from the contents of the header stored in step S506. Thereby, the upper layer protocol analysis unit 118 compares the payload and the content stored in step S506, and restores the header of each layer. Here, since a checksum is included in the IP header and the UDP header, the checksum is calculated from the contents of the payload and restored as a header. Thus, the entire voice packet before the header is omitted is restored. The process proceeds to step S507.

  Here, assuming that the value of the flag is 01011010, the flag represents the second layer, the third layer, the fourth layer, and the fifth to seventh layers with 2 bits each according to the OSI layer model. 00 represents “there was no corresponding header originally”, 01 represents “there was a header but was omitted because it was redundant”, and 10 “it could not be omitted”, so the LLC header was omitted, the IP header was omitted, and the UDP header, respectively. It can be interpreted as omission, no omission of the RTP header. Therefore, the portion after the flag of interest is interpreted as an RTP header, and the omitted header is restored based on the content stored in step S506. Further, the checksum is recalculated for the IP header and the UDP header, and the header is restored.

  By the above processing, even if a plurality of voice packets are originally combined into one radio frame, they are correctly divided into the original voice packets and passed to the protocol processing unit 117. The decoding task completes the decoding process within a specified delay time and reproduces it as sound.

Next, the task of base unit 400 will be described. However, since the wireless reception task is the same as that of the slave device 300, description thereof is omitted. The bridge task process will be described with reference to the flowchart of FIG. 20 showing the bridge task operation of the wireless LAN telephone system master according to the first embodiment of the present invention.
[Step S601]
The wired-wireless bridge unit 121 determines whether there is an entry in the reception packet queue 113. If there is an entry, the process proceeds to step S602; otherwise, the process proceeds to step S605.
[Step S602]
The wired-wireless bridge unit 121 extracts an entry from the reception packet queue 113.
[Step S603]
The wired-wireless bridge unit 121 refers to the contents of the entry extracted in step S602 and determines whether it is necessary to relay to the LAN side (wired). In this determination, the destination of the second layer is used. In the present embodiment, the second layer is determined based on the MAC address defined by IEEE 802.11. The address learning method for this determination is not related to the gist of the present invention, and is omitted. If relaying is necessary, the process proceeds to step S604; otherwise, the process proceeds to step S601.
[Step S604]
The wired-wireless bridge unit 121 converts the IEEE 802.11 MAC header format into the IEEE 802.3 MAC header format, and transmits the entry contents from the LAN communication unit 106. The process proceeds to step S601.
[Step S605]
The wired-wireless bridge unit 121 inquires of the LAN communication unit 106 whether data is received from the wired LAN. If it has been received, the process proceeds to step S606. Otherwise, the process proceeds to step S601.
[Step S606]
The wired-wireless bridge unit 121 receives received data from the LAN communication unit 106.
[Step S607]
The wired-wireless bridge unit 121 determines whether the reception data extracted in step S606 needs to be relayed to the wireless LAN side. Since the method of determining whether to relay is the same as the conventional bridge processing, it is omitted. If it is necessary to relay, the process proceeds to step S608; otherwise, the process proceeds to step S601.
[Step S608]
The wired-wireless bridge unit 121 converts the received data extracted in step S 606 from the IEEE 802.3 MAC header format to the IEEE 802.11 MAC header format, and puts the received data in the transmission packet queue 111.

Next, the wireless transmission task of base unit 400 will be described with reference to the flowchart of FIG. 21 showing the operation of the bridge task of the base unit of the wireless LAN telephone system according to Embodiment 1 of the present invention. The wireless transmission task of the parent device 400 is almost the same as the wireless transmission task of the child device 300, but the parent device 400 is different from the wireless transmission task of the child device 300 in that the transmission waiting allowable time is not calculated. Hereinafter, a different part from the radio | wireless transmission task of the subunit | mobile_unit 300 is demonstrated. The base unit 400 performs processing for a plurality of slave units 300 at the same time. Here, a description will be given focusing on the processing of base unit A 400 for handset A 300.
[Step S701]
This is the same as step S301 in FIG.
[Step S702]
The control unit 130 inquires of the QoS management unit 122 about the “service cycle” for the child device A 300, refers to the RTC 108, calculates the next transmission time, and updates the “next transmission time”. Here, since the service period is 10.24 ms and the value of the RTC 108 is 12:33 22.0113 994, the next transmission time is therefore 12:33 22.024.234.
[Steps S703 to S704]
This is the same as steps S303 to S304 in FIG.
[Step S705]
The control unit 130 inquires of the error rate determination unit 119 whether the error rate is lower than a preset threshold. The error rate determination unit 119 passes the determination result to the control unit 130. From the received determination result, if the error rate is low, the process proceeds to step S709; otherwise, the process proceeds to step S715.
[Steps S709 to S719]
This is the same as steps S309 to S319 in FIG.

  As described above, in base unit 400, packets that have arrived at transmission packet queue 111 by the time of transmission are unconditionally grouped into one radio frame (in the case of slave unit, it is determined whether or not the next transmission time is in time. If possible, the voice packets to be transmitted are stored and then transmitted together.)

  FIG. 22 is a diagram showing the timing of audio encoding and radio frame transmission in the conventional TDM system. As shown in the figure, the voice packet generated at the timing of C0 reaches the other party within the allowable delay time if it is originally transmitted during T0, but is transmitted at the timing of S0 in the conventional transmission method. In other words, in the conventional transmission method, the transmission is performed at the earliest transmission timing from the time when the transmission request is generated without considering at all when the transmission should be completed within the allowable delay time. On the other hand, FIG. 23 shows a diagram illustrating audio encoding and radio frame transmission timing according to the first embodiment of the present invention. Voice packets generated at C1 and C2 are transmitted together at the timing of S1. As described above, in the method according to the present invention, since a plurality of transmission packets are transmitted together in one frame within the allowable transmission timing, the amount of communication bandwidth consumed can be reduced. 22 and 23, when the transmission allowable timing is equal to or longer than the codec cycle, and the transmission timing cycle and the codec cycle are almost the same (in a wireless LAN telephone system, the system is often It can be seen that the transmission method according to the present invention can effectively use the communication band.

  As a result, the user can perform data communication without feeling an uncomfortable delay during a voice call and without stress even if data communication is performed at the same time.

  As described above, handset 300 of the wireless LAN telephone system according to the present embodiment inputs operation unit 101 for specifying a call destination, instructing a call when receiving a call, and instructing an end of call, and inputting voice. Audio input unit 102, audio output unit 103 for outputting audio, reception buffer 104 for accumulating received radio frames, transmission buffer 105 for accumulating data for transmission, and accumulation in this transmission buffer 105 Data is transmitted in the form of a radio frame, and the radio communication unit 107 that receives the radio frame and stores the contents of the frame in the reception buffer 104, the RTC 108 for measuring the passage of time, the audio delay allowable time, the audio A parameter storage unit 109 for storing a codec period, a voice codec delay, and a network delay amount specified in advance. To have.

  Then, the handset 300 of the wireless LAN telephone system further A / D-converts the voice input from the voice input unit 102 and converts (encodes) the voice data using a predetermined algorithm. The codec unit 110 that performs D / A conversion and outputs the audio packet to the audio output unit 103, the transmission packet queue 111 that stores the audio packet output by the codec unit 110 in the FIFO method, and the transmission A payload integration unit 112 that writes packets input to the transmission packet queue 111 within a waiting time into one frame and writes them to the transmission buffer 105, and receives the data received as a radio frame into packets and stores them in a FIFO manner. The contents stored in the packet queue 103 and the reception buffer 105 From the above, it is determined whether the packet is originally one voice packet. If a plurality of voice packets are integrated, the packet is divided into a plurality of voice packets and written in the received packet queue 113 by the FIFO method. And a speech delay allowable time, a speech codec period, a speech codec delay, a network delay amount, a predicted value of a wireless transmission period or a transmission waiting time, and an RTC stored in the parameter storage unit 109 The transmission waiting time calculation unit 115 that compares and refers to the values of the above and calculates the transmission waiting time, and controls the outgoing call, incoming call, connection / disconnection of the call, and a signal corresponding to each state of the call A call control unit 116 for outputting (dial tone, busy tone, ringer, ring back tone) to the voice output unit; Settings and release, and a protocol processing unit 117 for processing transmission and reception of voice packets during a call, a control unit 130 for controlling the entire apparatus.

  As a result, in communication with base unit 400, the overhead for radio frame formation is reduced, and the audio delay can be reduced.

  In addition, slave unit 300 of the wireless LAN telephone system of the present embodiment further includes TS management unit 120 that manages time slots, and performs wireless communication with master unit 400 by TDM. As a result, the overhead during radio frame conversion is reduced, the audio delay is reduced, the number of simultaneous calls per access point is increased, and data communication is performed when performing data communication during a call. Can use a large bandwidth.

  Furthermore, base unit 400 of the wireless LAN telephone system of the present embodiment has a wired / wireless bridge unit 121. The base unit 400 relays between different frames using the function of the wired-wireless bridge unit 121. That is, the wireless frame from the slave unit 300 is relayed to the Internet side as an Ethernet (registered trademark) frame using the LAN communication unit (wired), or the Ethernet (registered trademark) frame from the Internet side is relayed to the slave unit 300. Or relay it as a radio frame. For example, the MAC header format of IEEE802.11 is converted into the format of the MAC header of IEEE802.3, the content of the entry is transmitted from the LAN communication unit 106, and the received data is converted from the format of the IEEE802.3 MAC header to IEEE802.11. The frame is communicated between wired and wireless by relaying it to the MAC header format and putting it in the transmission packet queue 111.

(Embodiment 2)
FIG. 24 is a functional block diagram showing the configuration of the wireless LAN telephone system slave unit according to the second embodiment of the present invention. In FIG. 24, the slave unit 310 has a functional configuration indicated by 101 to 123. The hardware configuration of slave unit 310 is the same as that of the first embodiment (FIG. 2).

  In FIG. 24, reference numeral 101 denotes an operation unit for designating a call destination, instructing a call when receiving a call, and instructing an end of call. Reference numeral 102 denotes a voice input unit for inputting voice. Reference numeral 103 denotes an audio output unit for outputting audio. Reference numeral 104 denotes a reception buffer for accumulating data extracted from the received radio frame. Reference numeral 105 denotes a transmission buffer that accumulates data for wireless transmission. Reference numeral 107 denotes a wireless communication unit that converts the data stored in the transmission buffer 105 into a wireless frame and transmits the data, receives the wireless frame, and stores the contents of the frame in the reception buffer 104. Reference numeral 108 denotes an RTC for measuring the passage of time. Reference numeral 109 denotes a parameter storage unit that stores a voice delay allowable time, a voice codec period, a voice codec delay, and a network delay amount designated in advance.

  In addition, 110 performs A / D conversion on the voice input from the voice input unit 102, converts (encodes) the voice into a voice packet using a predetermined algorithm, and decodes the voice data using a predetermined algorithm. A codec unit that performs D / A conversion and outputs the result to the audio output unit 103. Reference numeral 111 denotes a transmission packet queue that stores a voice packet encoded by the codec unit 110 in a FIFO manner together with the time when encoding is completed, that is, the transmission request reception time. A payload integration unit 112 writes packets input to the transmission packet queue 111 within one transmission waiting time into one frame and writes them in a transmission buffer. Reference numeral 113 denotes a reception packet queue that disassembles data received as a radio frame into voice packets and stores them in a FIFO manner.

  Further, 114 determines whether or not the content stored in the reception buffer 104 was originally one voice packet. If a plurality of voice packets are integrated, the contents are separated into a plurality of voice packets, and the received packet queue. This is a payload division unit that writes data to 113 using a FIFO method. 115 refers to the allowable delay time of the voice, the codec period of the voice, the codec delay of the voice, and the network delay amount specified in advance stored in the parameter storage unit 109, and sets the value of the RTC 108 as the transmission request reception time. It is a transmission waiting time calculation unit that compares and calculates a transmission waiting time. 116 is a call control unit that controls outgoing / incoming calls, connection / disconnection of calls, and dial tone, busy tone, ringer, ring back tone according to the state of each call to the voice output unit 103. is there. Reference numeral 117 denotes a protocol processing unit that processes call setting and cancellation and voice packet transmission / reception during a call according to a designated protocol. A network delay measurement unit 123 measures the network delay. A control unit 130 controls the whole.

  The relationship with the hardware configuration of FIG. 2 will be described. The operation unit 101 includes a keyboard 211. The voice input unit 102 includes 208 microphones. The audio output unit 103 includes 210 speakers. 104 reception buffers, 105 transmission buffers, 109 parameter storage units, 111 transmission packet queues, and 113 reception packet queues are configured by 203 RAMs. The wireless communication unit 107 includes a baseband unit 205 and an RF 206. 108 RTCs are composed of 204 RTCs.

  The codec unit 110 includes 212 codecs, 207 A / D, and 209 D / A. 112 payload integration unit, 114 payload division unit, 115 transmission waiting time calculation unit, 123 network delay measurement unit, and 130 control unit are stored in the ROM of 202 by the CPU of 201. The program is configured by referring to data stored in the ROM 202 and referring to or changing data stored in the RAM 203.

  FIG. 25 is a functional block diagram showing the configuration of the wireless LAN telephone system base unit according to Embodiment 2 of the present invention. In FIG. 25, base unit 410 has a functional configuration indicated by reference numerals 104 to 121. The hardware configuration of base unit 410 is the same as that of the first embodiment (FIG. 4).

  In FIG. 25, reference numeral 104 denotes a reception buffer that accumulates data extracted from a received radio frame. Reference numeral 105 denotes a transmission buffer that accumulates data for wireless transmission. Reference numeral 106 denotes a LAN communication unit for connecting to a wired network. Reference numeral 107 denotes a wireless communication unit that converts the data stored in the transmission buffer 105 into a wireless frame and transmits the data, receives the wireless frame, and stores the contents of the frame in the reception buffer 104. Reference numeral 108 denotes an RTC for measuring the passage of time. Reference numeral 111 denotes a transmission packet queue that is stored in the FIFO method together with a transmission request reception time so that the later-described wired-wireless bridge unit 121 transmits a frame from the LAN side determined to be relayed as a wireless frame. A payload integration unit 112 writes the voice packets input to the transmission packet queue 111 within one transmission waiting time into one frame and writes them into a transmission buffer. Reference numeral 113 denotes a reception packet queue that disassembles data received as a radio frame into voice packets and stores them in a FIFO manner. 114 determines whether or not the content stored in the reception buffer 104 was originally one voice packet. When a plurality of voice packets are integrated, the contents are separated into a plurality of voice packets and stored in the reception packet queue 113. This is a payload division unit that writes in the FIFO method. Reference numeral 121 denotes a wired-wireless bridge unit that relays a frame between wired and wireless if necessary, and discards the frame otherwise. Reference numeral 130 denotes a control unit that controls the whole.

  The relationship with the hardware configuration of FIG. 4 will be described. The 104 reception buffer, 105 transmission buffer, 111 transmission packet queue, and 113 reception packet queue are configured by 203 RAMs. The wireless communication unit 107 includes a baseband unit 205 and an RF 206. 108 RTCs are composed of 204 RTCs. The LAN communication unit 106 includes a network interface 213.

  The payload integration unit 112, the payload division unit 114, the wired-wireless bridge unit 121, and the control unit 130 store programs stored in the ROM 202 of the CPU 201 in the ROM 202. This is configured by referring to the data stored in the memory, referring to the data stored in the RAM 203, or changing the data.

Since the overall configuration of the wireless LAN telephone system of the present embodiment is the same as that of the first embodiment, description thereof is omitted. The sequence chart showing the operation outline of the wireless LAN telephone system according to the second embodiment of the present invention in FIG. 26 shows the operation outline of the parent device 410 and the child device 310 of this embodiment. Note that this is almost the same as that in FIG. 6 in the first embodiment, except that there is no QoS securing and releasing process. In this description, it is assumed that the slave unit 310 is initially in a standby state.
[Steps E201 to E205]
This is the same as steps E01 to E05 in FIG. 6 in the first embodiment.
[Step E206]
In slave unit B300, when the user hears a ring tone and notices that he / she is receiving a call, he / she operates operation unit 101 to instruct a call. As a result, in handset B 300, control unit 130 receives the message “instructed to talk” from operation unit 101, and requests call control unit 116 to “connect the call”. Further, the call control unit 116 activates an encoding task and a decoding task. Thereafter, until the call disconnection is instructed, the codec unit 110 encodes the voice received from the voice input unit 102, and requests the protocol processing unit 117 to transmit the result as a voice packet to the child device A300. Then, as described above, the voice packet reaches the child device A300 via the parent device B400 and the parent device A400. Also, in the slave unit B300, the voice packet from the slave unit A300 received by the codec unit 110 via the wireless communication unit 107 and the protocol processing unit 117 is decoded, and the result is output to the voice output unit 103. Become. Proceed to step M208.
[Step M208]
This is the same as step M08 in FIG. 6 of the first embodiment. Proceed to step E210.
[Step E210]
Thereafter, a full-duplex communication path is secured, and a call becomes possible. Here, it is assumed that the communication band of the Internet is sufficiently wide and the delay is about several tens of ms. That is, it is assumed that the bottleneck of communication between the child device A300 and the child device B300 is between the child device and the parent device.
[Step M211]
During a call, the voice of the user of the slave unit A300 is input to the voice input unit 102 of the slave unit A300, encoded by the codec unit 110 as described above, and transmitted as a voice packet to the slave unit B300 by the protocol processing unit 117. In the slave unit B300, the codec unit 110 receives the voice packet via the wireless communication unit 107 and the protocol processing unit 117, decodes this, and outputs the result to the voice output unit 103 of the slave unit B300. The process in which the user's voice on the handset B300 side reaches the handset A300 is a process that is exactly symmetric to the above-described process, and therefore details are omitted.
[Step E212]
This is the same as step E12 in FIG. 6 of the first embodiment. Proceed to step M214.
[Step M214]
This is the same as step M14 in FIG. 6 of the first embodiment.
[Step E215]
This is the same as step E15 in FIG. 6 of the first embodiment. Proceed to step M217.
[Steps M217 to E218]
This is the same as steps M17 to E18 in FIG. 6 of the first embodiment.

  Next, the operation of the slave unit 310 will be described. FIG. 27 shows a task configuration of the wireless LAN telephone system slave unit according to the second embodiment of the present invention. Compared with the first embodiment (FIG. 7), a measurement task is added. On the other hand, the task configuration of base unit 410 is the same as that of the first embodiment (FIG. 8). First, the operation of the task of the slave unit 310 will be described. Of the tasks of the slave unit 310, the encoding task, decoding task, and protocol processing task are the same as those in the first embodiment, and a description thereof will be omitted.

A call control task of handset 310 in the present embodiment will be described along the state chart of FIG. First, the operation of the call control task will be described from the side of handset A300 with respect to a series of processes in which handset A300 is turned on and the user of handset A300 makes a call, makes a call, and disconnects.
[Step E101]
When the operation unit 101 instructs to turn on the power of the slave unit, the control unit 130 activates a call control task, a protocol processing task, a wireless transmission task, and a wireless reception task. When the call control task is activated, it transitions to a standby state. As a result, incoming and outgoing calls can be made thereafter.
[Step E102]
The user operates the operation unit 101 on the child device A300 to make a call to the child device B300. The control unit 130 of the slave unit A 300 receives the “call” notification from the operation unit 101, receives the call destination number, and requests the call control unit 116 to designate the other party number and make a “call connection” request. The call control unit 116 requests the protocol processing unit 117 to transmit the “INVITE” message to the child device B 300. Slave device B300 receives the “INVITE” message, becomes in-call, and returns a “RINGING” message to slave device A300. The call control unit 116 of the child device A300 receives the “RINGING” message from the child device B300 via the protocol processing unit 117, and transitions to a calling state. The call control unit 116 outputs the RBT to the voice output unit 103 to inform the user that “calling”.
[Step E103]
In cordless handset B300, a ringer (ringing tone) is ringing, and the user notices the ringing tone and accepts the incoming call. Thus, after the encode task and the decode task are activated, a “CONNECT-OK” message is transmitted to the child device A300. In handset A 300, call control unit 116 receives the “CONNECT-OK” message via protocol processing unit 117.

As a result, the call control unit 116 activates the above-described encoding task and decoding task, and the codec unit 110 performs A / D conversion and encoding on the subsequent voice from the voice input unit 102 and sends it to the protocol processing unit 117 as a voice packet. hand over. Further, the codec unit 110 decodes and D / A converts the voice packet received by the protocol processing unit 117, and outputs it to the voice output unit 103. Transition during a call.
[Step E109]
When the user of the child device A300 finishes the call, the operation unit 101 of the child device A300 is operated to disconnect the call. The control unit 130 receives a disconnection operation notification from the operation unit 101 and requests the call control unit 116 to perform “call disconnection”. The call control unit 116 stops the encoding task and the decoding task. As a result, the call control unit 116 requests the protocol processing unit 117 to send a “BYE” message to the child device B 300. The protocol processing unit 117 transmits data indicating a “BYE” message to the parent device A 400 via the wireless processing unit 107 and arrives at the child device B 300 via the Internet and the parent device B 400. Upon receiving the “BYE” message, handset B300 returns “BYE-OK” to handset A300. In handset A300, call control unit 116 receives the "BYE-OK" message via wireless communication unit 107 and protocol processing unit 117. Thereby, it changes to a standby state.
[Step E107]
When a user cancels a call while making a call, the operation unit 101 issues a call cancellation instruction, the control unit 130 receives a call cancellation instruction from the operation unit 101, and issues a call to the call control unit 116. Request cancellation. The call control unit 116 requests the protocol processing unit 117 to transmit a “CANCEL” message to the child device B 300. Handset B300 stops the ringer and sends a "CANCEL-OK" message to handset A300. In the slave unit A300, when the protocol processing unit 117 receives “CANCEL-OK” from the slave unit B300 and notifies the call control unit 116, the call control unit 116 transitions to a standby state.

Next, the operation of the call control task as seen from the handset B 300 side will be described.
[Step E104]
The protocol processing unit 117 receives the “INVITE” message from the child device A 300 and notifies the call control unit 116 of it. The call control unit 116 requests the protocol processing unit 117 to return a “RINGING” message to the child device A 300. The call control unit 116 outputs a ringer to the voice output unit 103 to inform the user that an incoming call has occurred. The call control unit 116 transitions to an incoming call state.
[Step E105]
The user learns that the ringer is receiving a call and operates the operation unit 101 to answer the incoming call. The control unit 130 receives an incoming response from the operation unit 101 and requests the call control unit 116 for a response.

As a result, the call control unit 116 requests the protocol processing unit 117 to transmit a “CONNECT-OK” message to the child device A300. The protocol processing unit 117 transmits a “CONNECT-OK” message to the child device A300. Further, the call control unit 116 stops the ringer output to the audio output unit 103, starts the encoding task and the decoding task, and the audio from the subsequent audio input unit 102 is A / D converted / encoded, and the audio packet To the child device A300, and the voice packet from the child device A300 is decoded and D / A converted and output from the voice output unit 103.
[Step E109]
The protocol processing unit 117 receives the “BYE” message from the child device A 300 and notifies the call control unit 116 of it. The call control unit 116 stops the encoding task and the decoding task, and transitions to a standby state. If the user of handset A300 cancels the call while making a call,
[Step E108]
The protocol processing unit 117 receives the “CANCEL” message and notifies the call control unit 116 of it. The call control unit 116 stops the ringer, requests the protocol processing unit 117 to transmit a “CANCEL-OK” message to the child device A300, and shifts to a standby state.

Next, the measurement task will be described with reference to the flowchart of FIG. 28 showing the operation of the measurement task of the wireless LAN telephone system slave unit according to the second embodiment of the present invention. In the present embodiment, it is assumed that the slave units 310 that are making a call are preliminarily combined with each other's RTC 108 by another method. As a method for adjusting the clocks of each other, a method using GPS and a method using a protocol called NTP are common, but details are not described here.
[Step S801]
The network delay measurement unit 123 refers to the reception packet queue 113 and determines whether or not the measurement packet has arrived. If it has arrived, the process proceeds to step S802; otherwise, the process proceeds to S803.
[Step S802]
The network delay measurement unit 123 takes out the packet from the reception packet queue 113.
[Step S803]
The network delay measurement unit 123 refers to the contents of the extracted packet, reads when the packet is transmitted, refers to the RTC 108, and compares it with the current time. The result is written in the parameter storage unit 109 as a network delay amount. The process proceeds to step S801. Here, it is assumed that the time written in the packet is 12:33 12.654 223. If the RTC 108 indicates 12:33 12.734 223, the time difference is 80 ms, and this is written in the parameter storage unit 109 as a network delay amount.
[Step S804]
The network delay measurement unit 123 refers to the RTC 108 and determines whether the scheduled transmission time has come. If the scheduled time is reached, the next scheduled transmission time is set, and the process proceeds to step S804. Otherwise, the process proceeds to step S801. Here, the measurement packet is transmitted once every 5 seconds. Therefore, the scheduled transmission time is 5 seconds later.
[Step S805]
The network delay measurement unit 123 refers to the RTC 108, reads the current time, and puts this in the transmission packet queue 111 as the packet contents. The process proceeds to step S801.

  As described above, the slave unit 310 exchanges measurement packets with each other to measure the delay amount of the network, and based on this, the transmission waiting allowable time is calculated by the wireless transmission task. As a result, even if the network traffic fluctuates and the amount of network delay changes, the transmission waiting allowable time can be calculated so as to cancel this change, so that a stable call can be secured.

FIG. 29 is a flowchart showing the operation of the wireless transmission task of the wireless LAN telephone system slave unit according to the second embodiment of the present invention. Compared with that of the first embodiment, it is not determined whether or not a plurality of voice packets are combined into one frame based on the error rate. That is, in the present embodiment, a process of always combining a plurality of voice packets into one frame is performed.
[Step S901]
This is the same as step S301 in FIG. 13 in the first embodiment.
[Step S902]
The control unit 130 predicts the scheduled transmission time. In this embodiment, it is assumed that communication is performed by the CSMA / CA method. In the CSMA / CA method, when a transmission request is generated, it is determined whether transmission is possible and transmission is performed. Next, it is only necessary to predict the time when the transmission request is generated. Therefore, when the next codec is finished, a transmission request is generated. Further, in the CDMA / CA system, since transmission is performed after waiting for a random time by a back-off algorithm after a transmission request is actually generated, 1 ms is adopted here as an average waiting time. Since the current time is 12:33 22.003 994 from the RTC 108, the control unit 130 refers to the parameter storage unit 109, sets the next transmission time from the codec period to 10 ms, and sets the average transmission waiting time to 1 ms, and 11 ms. Expect later 12:33 32.024 994.
[Step S903]
This is the same as step S303 in FIG. 13 in the first embodiment.
[Step S904]
The control unit 130 pays attention to the first entry in the transmission packet queue 111. The process proceeds to step S906.
[Step S906]
The control unit 130 requests the transmission waiting allowable time calculation unit 115 to calculate the transmission waiting allowable time by passing the transmission request reception time of the entry of interest. Thereby, the allowable delay time calculation unit calculates the allowable delay time with reference to the parameter storage unit 109, the RTC 108, and the transmission request reception time recorded in association with the entry. First, the transmission waiting time is obtained from the RTC 108 and the transmission request reception time. Here, it is assumed that the following values shown in (Equation 5) are obtained.

  Further, it is assumed that (Equation 6) is stored in the parameter storage unit 109 in advance.

  Since these values are the same as those described in the first embodiment, description thereof will be omitted.

  Based on the above values, the transmission waiting allowable time is calculated by (Equation 7).

FIG. 14 illustrates the above formula in an easy-to-understand manner. The allowable transmission waiting time for the entry of interest from the above is 13 ms.
[Step S907]
The control unit 130 determines whether the next transmission is in time. If it is determined that it is in time, the process proceeds to step S909; otherwise, the process proceeds to step S908. Here, the current time is 12:33 22.013 994. In this case, since the transmission waiting allowable time is 13 ms, it is understood that the transmission should be performed by the worst, 12:33 22.026 994. Since the next transmission time is 12:33 32.024 994, it is determined that the next transmission is in time.
[Step S908]
The control unit 130 determines whether the data to be transmitted already exists in the transmission buffer 105 at the current transmission timing. That is, even if it is determined in step S907 that the next transmission is in time, if there is already data to be transmitted in the transmission buffer 105, it is better to transmit the data collectively. That is, if it exists, the process proceeds to step S909, and otherwise, the process proceeds to step S901. Here, the description will be continued assuming that no data exists in the transmission buffer 105. In this case, the process proceeds to step S901. Thereafter, it is assumed that time elapses and the time becomes 12:33 32.024 994. At this time, it is assumed that the next transmission time is 12:33 32.035 994. Here, step S901 to step S904 and step S906 are executed. Here, it is assumed that two voice packets are enqueued in the transmission packet queue 111 as shown in FIG. In step S907, since it is determined that entry 1 is not in time for the next transmission, the process proceeds to step S909.
[Steps S909 to S911]
This is the same as steps S309 to S311 in FIG. 13 in the first embodiment.
[Step S912]
The control unit 130 pays attention to the next entry. The process proceeds to step S906.
[Steps S913 to S914]
This is the same as steps S313 to S314 in FIG. 13 in the first embodiment.

  In the above example, Step S907, Step S909, and Step S910 are executed. In Step S911, since there is another entry in the transmission packet queue 111, the process proceeds to Step S912, and the process proceeds to Step S906 and Step S907. In step S907, it is determined that entry 2 is in time for the next transmission time, and the process proceeds to step S908. In step S908, since the data corresponding to entry 1 has already been written in the transmission buffer 105, the process proceeds to step S909. After the data are merged in step S910, it is determined in step S911 that there is no unprocessed entry, and the process proceeds with steps S913 and S914.

Next, data merge processing will be described with reference to the flowchart of FIG. 30 showing transmission merge processing of the wireless LAN telephone system according to Embodiment 2 of the present invention. Compared with the first embodiment, payloads are simply combined into one frame without performing upper protocol analysis processing.
[Step S1001]
The payload integration unit 112 determines whether data is written in the transmission buffer 105. If written, the process proceeds to step S1004. Otherwise, the process proceeds to step S1002.
[Step S1002]
The payload integration unit 112 writes the MAC header in the transmission buffer 105. The process proceeds to step S1004.
[Steps S1004 to S1006]
This is the same as steps S404 to S406 in FIG. 16 in the first embodiment.

  As described above, the state of the transmission buffer 105 thus written is shown as a frame when a plurality of voice packets are combined into one wireless frame by the wireless LAN telephone system according to the second embodiment of the present invention shown in FIG. The format is shown in the figure.

Next, the operation of the wireless reception task will be described with reference to the flowchart of FIG. 32 showing the operation of the wireless reception task of the wireless LAN telephone system according to the second embodiment of the present invention. In the present embodiment, the wireless reception task performs the same processing on both the slave unit 310 and the master unit 410. Here, it is assumed that the radio frame addressed to the own station is received by the radio communication unit 107 and the contents of the frame are written in the reception buffer 104 as data.
[Steps S1101 to S1104]
This is the same as steps S501 to S504 in FIG. 19 in the first embodiment.
[Step S1105]
The payload dividing unit 114 interprets the first byte as a delimiter, reads a value, obtains how many bytes the payload is, and takes out subsequent payloads. The process proceeds to step S1107.
[Steps S1107 to S1110]
This is the same as steps S507 to S510 in FIG. 19 in the first embodiment.

  By the above processing, even if a plurality of voice packets are originally combined into one radio frame, they are correctly divided into the original voice packets and passed to the protocol processing unit 117. The decoding task completes the decoding process within a specified delay time and reproduces it as sound.

Next, regarding the parent device 410, the task configuration of the parent device 410 is the same as that of the first embodiment, and the bridge task is the same as that of the first embodiment. Since the wireless reception task is the same as that of the child device of the second embodiment, the description thereof is omitted, and only the wireless transmission task of the parent device 410 is described here. The wireless transmission task of base unit 410 in the present embodiment will be described with reference to the flowchart of FIG. 33 showing the operation of the wireless transmission task of the wireless LAN telephone system base unit according to the second embodiment of the present invention.
[Steps S1201 to S1203]
This is the same as steps S701 to S703 in FIG. 21 in the first embodiment.
[Step S1204]
The control unit 130 pays attention to the first entry in the transmission packet queue 111. It progresses to step S1209.
[Steps S1209 to S1211]
This is the same as steps S709 to S711 in FIG. 21 in the first embodiment.
[Step S1212]
The control unit 130 pays attention to the next entry. It progresses to step S1209.
[Steps S1213 to S1214]
This is the same as steps S713 to S714 in FIG. 21 in the first embodiment.

  As described above, if the slave unit 310 and the master unit 410 described in this embodiment are used in combination, the wireless communication band can be used effectively, and the delay of voice during a call is practical. It is possible to keep it within a certain range.

  As described above, the slave unit 310 of the wireless LAN telephone system according to the present embodiment has the network delay measuring unit 123 that measures the delay amount of the network. Even if it fluctuates, the delay of the voice becomes constant within an allowable range, and even if the delay of the network becomes large, the voice is not interrupted, and the delay becomes large and the conversation does not become confused.

  As described above, the wireless LAN telephone communication method and the wireless LAN telephone system according to the present invention do not consume a communication band more than necessary, and can transmit and receive audio data within an allowable range of audio delay. It is possible to provide a calling environment in which an uncomfortable delay is not felt to a speaker even if a phone call occurs. As a result, the number of slave units that can be accommodated per master unit can be greatly increased. In addition, even for users who are performing data communication using the same wireless communication band, a voice communication does not compress the data communication band, so that a communication environment with less stress can be provided.

Functional block diagram showing the configuration of the wireless LAN telephone system slave unit according to the first embodiment of the present invention Device block diagram showing the configuration of the wireless LAN telephone system slave unit according to the first embodiment of the present invention Functional block diagram showing the configuration of the wireless LAN telephone system base unit according to the first embodiment of the present invention Device block diagram showing the configuration of the wireless LAN telephone system base unit according to the first embodiment of the present invention 1 shows an overall configuration of a wireless LAN telephone system according to a first embodiment of the present invention. Sequence chart showing an operation outline of the wireless LAN telephone system according to the first embodiment of the present invention The figure which shows the task structure of the wireless LAN telephone system subunit | mobile_unit by Embodiment 1 which concerns on this invention The figure which shows the task structure of the main | base station of the wireless LAN telephone system by Embodiment 1 which concerns on this invention The flowchart which shows operation | movement of the encoding task of the wireless LAN telephone system subunit | mobile_unit by Embodiment 1 which concerns on this invention The flowchart which shows the operation | movement of the decoding task of the wireless LAN telephone system subunit | mobile_unit by Embodiment 1 which concerns on this invention Statechart showing operation of call control task of wireless LAN telephone system slave unit according to first and second embodiments of the present invention Flowchart showing the operation of the protocol processing task of the wireless LAN telephone system slave unit according to the first and second embodiments of the present invention. The flowchart which shows operation | movement of the radio | wireless transmission task of the wireless LAN telephone system subunit | mobile_unit by Embodiment 1 which concerns on this invention The figure which shows the breakdown of the delay amount of the audio | voice of the wireless LAN telephone system by Embodiment 1 and 2 which concerns on this invention The figure which shows the content of the transmission packet queue 111 of the wireless LAN telephone system subunit | mobile_unit by Embodiment 1 which concerns on this invention. 7 is a flowchart showing a transmission merge process of the wireless LAN telephone system according to the first embodiment of the present invention. The figure which shows the format of the radio | wireless frame by IEEE802.11. The figure which shows a frame format when two audio | voice packets are put together into one radio | wireless frame by Embodiment 1 which concerns on this invention. The flowchart which shows operation | movement of the reception task of the wireless LAN telephone system by Embodiment 1 which concerns on this invention The flowchart which shows operation | movement of the bridge | bridging task of the main | base station of the wireless LAN telephone system by Embodiment 1 which concerns on this invention The flowchart which shows the operation | movement of the radio | wireless transmission task of the main | base station of the wireless LAN telephone system by Embodiment 1 which concerns on this invention Diagram showing audio encoding and radio frame transmission timing in the conventional TDM system The figure which showed the audio | voice encoding by Embodiment 1 which concerns on this invention, and the transmission timing of a radio | wireless frame Functional block diagram showing the configuration of the wireless LAN telephone system slave unit according to the second embodiment of the present invention Functional block diagram showing a configuration of a wireless LAN telephone system base unit according to Embodiment 2 of the present invention Sequence chart showing an outline of operation of the wireless LAN telephone system according to the second embodiment of the present invention The figure which shows the task structure of the wireless LAN telephone system subunit | mobile_unit by Embodiment 2 which concerns on this invention. Flowchart according to the second embodiment of the present invention illustrating the operation of the measurement tasks of the wireless LAN telephone system handset The flowchart which shows operation | movement of the radio | wireless transmission task of the wireless LAN telephone system subunit | mobile_unit by Embodiment 2 which concerns on this invention. 7 is a flowchart showing transmission merge processing of the wireless LAN telephone system according to the second embodiment of the present invention. The figure which shows a frame format when several audio | voice packets are put together into one radio | wireless frame by the wireless LAN telephone system by Embodiment 2 which concerns on this invention. The flowchart which shows the operation | movement of the radio | wireless reception task of the wireless LAN telephone system by Embodiment 2 which concerns on this invention. The flowchart which shows operation | movement of the wireless transmission task of the wireless LAN telephone system main | base station by Embodiment 2 which concerns on this invention

Explanation of symbols

101 Operation Unit 102 Audio Input Unit 103 Audio Output Unit 104 Reception Buffer 105 Transmission Buffer 106 LAN Communication Unit 107 Wireless Communication Unit 108 RTC
109 Parameter storage unit 110 Codec unit 111 Transmission packet queue 112 Payload integration unit 113 Reception packet queue 114 Payload division unit 115 Transmission waiting time calculation unit 116 Call control unit 117 Protocol processing unit 118 Upper protocol analysis unit 119 Error rate determination unit 120 TS Management unit 121 Wired-to-wireless bridge unit 122 QoS management unit 123 Network delay measurement unit 130 Control unit 201 CPU
202 ROM
203 RAM
204 RTC
205 Baseband part 206 RF
207 A / D
208 Microphone 209 D / A
210 Speaker 211 Keyboard 212 Codec 213 Network I / F

Claims (7)

In a telephone system using a wireless LAN,
On the transmission side, the transmission delay allowable value is a value obtained by subtracting the audio codec period, the audio codec delay × 2, the codec waiting time, the transmission waiting time, and the network delay amount specified in advance from the allowable audio delay time. Calculate the time, analyze a plurality of voice packets within the allowable transmission waiting time period , and analyze at least one upper transmission protocol header of LLC, IP, UDP, RTP, and omit common parts based on the analysis result one of the frame, as well as collectively transmitted,
A wireless LAN telephone communication method characterized in that, on the receiving side, a plurality of voice packets collected in one frame are divided as they were. The wireless LAN telephone communication method according to claim 1,
A wireless LAN telephone communication method, wherein QoS is ensured and voice is exchanged by a TDM method when communication is performed between the transmission side and the reception side. In the wireless LAN telephone communication method according to any one of claims 1 or 2,
On the transmitting side, when the error rate of wireless communication is below a predetermined threshold, the plurality of voice packets are transmitted together, and when the error rate of wireless communication exceeds a predetermined threshold, one frame is transmitted. A wireless LAN telephone communication method characterized in that transmission is performed without putting together. A wireless LAN telephone communication program characterized by describing the procedure of the wireless LAN telephone communication method according to any one of claims 1 to 3 . A recording medium in which the wireless LAN telephone communication program according to claim 4 is recorded. A handset of a wireless LAN telephone system that uses wireless LAN to packetize and transmit and receive voice,
The allowable transmission delay time is calculated by subtracting the audio codec period, the audio codec delay × 2, the codec waiting time, the transmission waiting time, and the network delay amount specified in advance from the allowable audio delay time. A transmission waiting time calculation unit;
A payload integration unit for generating transmission data by combining voice packets input within a transmission waiting time into one frame;
An upper protocol analysis unit that analyzes at least one upper protocol header of LLC, IP, UDP, and RTP of the voice packet;
The received data is judged whether or not a original one voice packet, when a plurality of voice packets are integrated, have a decomposing payload division unit the received data to a plurality of voice packets,
The upper protocol analysis unit analyzes an upper protocol header of a voice packet, and the payload integration unit combines the frames into one frame in which common parts are omitted based on an analysis result by the upper protocol analysis unit. Wireless LAN phone system handset. In the wireless LAN telephone system handset according to claim 6 ,
A wireless LAN telephone system slave unit further comprising a time slot management unit for managing time slots and performing wireless communication with a parent unit by TDM.

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