JP5603782B2 - Intercom system for multifamily housing and trunk line distribution device - Google Patents

Description

The present invention relates to an intercom system for collective housing and a trunk line distribution device .

  In the conventional intercom system for apartment houses, the audio and video signals are analog-modulated between the common unit (lobby interphone) installed in the common entrance (lobby) of the apartment house and the dwelling unit installed in each unit. Was being transmitted. On the other hand, in recent years, in order to respond to needs such as an increase in the number of channels, an intercom system for an apartment house that digitally modulates and transmits audio and video has been proposed (see, for example, Patent Document 1).

  FIG. 3 is a system configuration diagram showing a conventional intercom system for an apartment house using a digital transmission system. In this conventional example, common unit devices (lobby intercoms) C1 and C2 installed at the common entrance of the apartment house, dwelling unit A installed in each dwelling unit, and lobby intercoms C1 and C2 via the common unit trunk lines LC1 and LC2, A trunk distribution device B connected to C2 and connected to the dwelling trunks LS1 and LS2 is provided. A large number of branching devices D are connected to the dwelling unit trunk lines LS1 and LS2, and the dwelling unit A of each dwelling unit is connected to the dwelling unit line LA branched from the dwelling unit trunk lines LS1 and LS2 by each branching unit D. In addition, the terminal of each dwelling unit trunk line LS1 and LS2 is terminated with a terminator E.

  The lobby interphones C1 and C2 divide the audio collected by the microphone and the digital data of the video captured by the imaging device into packets and transmit the packets. Packets (transmission signals) transmitted from the lobby intercoms C1 and C2 are received by the trunk distribution device B via the shared trunks LC1 and LC2. The main line distribution device B distributes (relays) packets received from the lobby intercoms C1 and C2 to the dwelling unit main lines LS1 and LS2. Then, the packet relayed by the trunk distribution device B is received only by the dwelling unit A having an address that matches the destination address. In the dwelling unit A, an analog audio signal is decoded from audio or video digital data included in the received packet, the audio is played from the speaker, and the video is displayed on a display device such as a liquid crystal display.

  Furthermore, the dwelling unit A divides the voice digital data collected by the microphone into packets and transmits it through the dwelling unit line LA. A packet (transmission signal) transmitted from the dwelling unit A is received by the trunk distribution device B via the dwelling unit trunks LS1 and LS2. The trunk line distribution device B relays the packet received from the dwelling unit A to the shared part trunk lines LC1 and LC2. Then, the packet relayed by the main line distributor B is received only by the lobby intercoms C1 and C2 having an address that matches the destination address. In the lobby intercoms C1 and C2, the voice digital data included in the received packet is decoded and the voice is emitted from the speaker. In this way, a visitor and a resident can make an interphone call using the lobby intercom C1 and the dwelling unit A, respectively.

Here, consider a case where a packet (transmission signal) transmitted via the dwelling unit trunk lines LS1 and LS2 is subjected to multicarrier adaptive modulation. For example, when a transmission signal is transmitted from the dwelling unit A that is branched and connected to the dwelling unit main line LS1, channel estimation of the dwelling unit main line LS1 is performed between the dwelling unit A and the main line distribution device B. That is, a packet including a control command (channel estimation request) for requesting the processing of the channel estimation for the mains distribution unit B (request packet), the transmission signal is digitally modulated using all subcarriers, dwelling unit A To the trunk distribution device B.

  When receiving the request packet transmitted from the dwelling unit A, the trunk distribution device B calculates the S / N ratio for each subcarrier when the request packet is received according to the channel estimation request, and calculates the calculated S / N ratio. Based on the above, it is determined whether or not each subcarrier can be used. Further, the main line distributor B determines the digital modulation scheme (multilevel modulation degree) based on the S / N ratios of all the subcarriers determined to be usable, and information on the subcarrier to be used and the multilevel modulation degree. Is sent back to the requesting dwelling unit A.

  In the dwelling unit A, when the reply packet transmitted from the trunk distribution device B is received, the subcarrier and the multi-level modulation degree are determined based on the information included in the reply packet, and the packet with the sub-carrier and the multi-level modulation degree is determined. The transmission signal obtained by digitally modulating the signal is transmitted through the main unit LS1.

JP 2010-178073 A

  By the way, as shown in FIG. 4, the trunk distribution apparatus B in the conventional example includes a plurality of dwelling trunk lines, each of which has a circuit for performing digital carrier and other digital data such as video and multi-carrier adaptive modulation and demodulating the received signal. Shared by LS1, ... That is, a plurality of dwelling unit trunk lines LS1, LS2 are connected in parallel to the transmission end Tx and the reception end Rx of the circuit via transmission amplifiers TA1, TA2 and reception amplifiers RA1, RA2, respectively. Therefore, the request packet transmitted from the dwelling unit A that is branched and connected to one dwelling unit trunk line LS1 and the request packet that is transmitted from the dwelling unit A that is branched and connected to the other dwelling unit trunk line LS2 are There was a risk of collision. This is because the dwelling units A branched and connected to different dwelling trunks LS1 and LS2 are connected via directional transmission amplifiers TA1 and TA2 or reception amplifiers RA1 and RA2, as shown in FIG. Therefore, the packet sent out on the main unit LS1 is amplified by the receiving amplifier RA1, but is not delivered to the input terminal of the transmission amplifier TA2 or the main unit LS2, and the packet sent out on the main unit LS2 is received by the receiving amplifier RA2. Is not distributed to the input end of the transmission amplifier TA1 or the dwelling unit trunk line LS1. Thus, even if the carrier sense is executed before transmitting the request packet, the carrier of the transmission signal transmitted by the other party cannot be detected, and the collision in the trunk distribution apparatus B cannot be avoided. If such request packet collisions occur frequently, channel estimation processing is not performed normally and communication cannot be started.

  The present invention has been made in view of the above problems, and an object of the present invention is to increase the probability that channel estimation is performed while suppressing collision of transmission signals.

An intercom system for collective housing according to the present invention includes a trunk distribution device that distributes a transmission signal transmitted from a shared device installed at a shared entrance via a shared trunk to a plurality of residential trunks, and the plurality of residential trunks. A plurality of dwell units connected to each other, and the dwell unit transmits a transmission signal for notifying the trunk distribution device of the start of channel estimation before requesting channel estimation of multicarrier adaptive modulation. The trunk line distribution apparatus multicasts or broadcasts a transmission signal for responding to the notification.

  In this collective housing intercom system, the time length of the transmission signal for notifying the start of channel estimation and the time length of the transmission signal for responding to the notification are shorter than the time length of the transmission signal for the channel estimation request. It is preferable.

  In this collective housing intercom system, the dwelling unit multicasts or broadcasts a transmission signal for notifying the start of channel estimation, and the trunk distribution device multicasts or broadcasts a transmission signal for a response to the notification. It is preferable.

  In the collective housing intercom system, the dwelling unit transmits the notification of the channel estimation start using a transmission signal modulated by a modulation method having a relatively low multilevel modulation degree, and the trunk distribution device responds to the notification. It is preferable that the response is returned as a transmission signal modulated by a modulation method having a relatively low multilevel modulation.

  In this collective housing intercom system, the dwell unit continuously transmits a transmission signal for notifying the start of channel estimation, and the trunk distribution device continuously transmits a transmission signal for a response to the notification. preferable.

  In this collective housing intercom system, the dwelling unit transmits a transmission signal for notifying the start of channel estimation, including a scheduled time until channel estimation processing based on the channel estimation request is completed, and the trunk line It is preferable that the distribution apparatus transmits a transmission signal for responding to the notification including a scheduled time until the channel estimation process is completed.

The trunk distribution device according to the present invention distributes a transmission signal transmitted from a common unit installed at a common entrance via a common unit trunk to a plurality of dwelling mains, and is branched and connected to each of the plurality of dwelling mains. A trunk distribution device that requires multi-carrier adaptive modulation channel estimation from a plurality of dwelling units, and that is transmitted from the dwelling unit prior to the channel estimation request, and a transmission signal for notifying the start of the channel estimation Is received, a transmission signal for responding to the notification is multicast or broadcasted.

The intercom system for multi-dwelling houses and the main line distribution device according to the present invention have an effect of suppressing the collision of transmission signals and increasing the probability that channel estimation is performed.

It is a system configuration figure showing an embodiment. It is a sequence diagram for demonstrating the channel estimation process in the same as the above. It is a system configuration diagram of a conventional example. It is a block diagram which shows the principal part of the trunk line distribution apparatus same as the above.

  As shown in FIG. 1, the intercom system for collective housing of this embodiment is shared with the common unit devices (lobby intercoms) C1 and C2 installed at the common entrance of the collective housing and the dwelling unit A installed in each dwelling unit. The main line distribution device B is connected to the lobby intercoms C1 and C2 via the managerial lines LC1 and LC2 and connected to the dwelling main lines LS1 and LS2. A large number of branching devices D are connected to the dwelling unit trunk lines LS1 and LS2, and the dwelling unit A of each dwelling unit is connected to the dwelling unit line LA branched from the dwelling unit trunk lines LS1 and LS2 by each branching unit D.

  The lobby intercoms C1 and C2 are an imaging device that picks up the visitors, a microphone and a speaker, a numeric keypad or touch panel for the visitor to enter the dwelling unit number of the visited residence, and the voice and video shared trunk lines LC1 and LC2. A transmission unit for transmitting packets through the network. In the lobby intercoms C1 and C2, when the ten key switch or touch panel is operated and the operation input of the dwelling unit number of any dwelling unit is accepted, the packet storing the dwelling unit number in the data field and the image of the visitor imaged by the imaging device A packet storing (video information) in the data field is transmitted (packet transmission) from the transmission unit to the address of the trunk distribution device B via the shared trunks LC1 and LC2.

  The trunk line distribution device B is connected to the first transmission processing unit 31 that performs packet transmission between the lobby intercoms C1 and C2 via the shared trunk lines LC1 and LC2 and the dwelling unit A via the residential unit trunk lines LS1 and LS2. A second transmission processing unit 32 that performs packet transmission, and a control unit 30 that controls the first transmission processing unit 31 and the second transmission processing unit 32. The control unit 30 includes hardware such as a CPU and a memory, and various programs (software) executed by the CPU, and includes an address assigned to the dwelling unit A of each dwelling unit and a dwelling unit number of the dwelling unit. The correspondence is stored in the memory. Then, the control unit 30 of the trunk line distribution device B compares the dwelling unit number stored in the data field of the packet received from the lobby intercoms C1 and C2 with the correspondence and converts it into an address. And the control packet in which the call command for notifying the call from the lobby intercoms C1 and C2 is stored in the data field and the video packet in which the video information is stored in the data field are sent from the second transmission processing unit 32 to the dwelling unit main line LS1. , Sent to LS2.

  Here, the transmission end of the first transmission processing unit 31 is connected to the common unit trunk lines LC1 and LC2 via the transmission amplifiers 33A and 33B, and the reception end of the first transmission processing unit 31 is shared via the reception amplifiers 34A and 34B. Connected to the trunk lines LC1 and LC2. The transmission end of the second transmission processing unit 32 is connected to the dwelling unit trunk lines LS1 and LS2 via transmission amplifiers 35A and 35B, and the reception end of the second transmission processing unit 32 is set to the dwelling unit trunk line LS1 via reception amplifiers 36A and 36B. , Connected to LS2. That is, a transmission signal transmitted from the transmission end of the first transmission processing unit 31 flows through all the shared-part trunk lines LC1 and LC2, and a transmission signal transmitted from the transmission end of the second transmission processing unit 32 is transmitted to all the dwelling unit trunk lines LS1. , Will flow to LS2.

  The dwelling unit A includes a dwelling unit control unit 1, a transmission processing unit 2, a call processing unit 3, a microphone 4, a speaker 5, an A / D converter 6, a D / A converter 7, a video processing unit 8, a display unit 9, An operation input receiving unit 10 is provided. The sound collected by the microphone 4 is converted into an electrical signal (voice signal), and the analog voice signal (speech voice signal) output from the microphone 4 is converted into a digital voice signal (speech) by the A / D converter 6. Voice data) and input to the call processing unit 3. Further, a digital voice signal (received voice data) output from the call processing unit 3 is converted into an analog voice signal (received voice signal) by the D / A converter 7. An analog received voice signal output from the D / A converter 7 is input to the speaker 5, and a voice (received voice) is generated from the speaker 5.

  The call processing unit 3 includes a voice switch, an echo canceller, and the like, and performs signal processing on the received voice signal input from the transmission processing unit 2 and the transmission voice signal input from the A / D converter 6 to perform howling and The echo is suppressed to realize a good hands-free call. The transmitted voice signal processed by the call processing unit 3 is output to the transmission processing unit 2.

  The display unit 9 includes a display device such as a liquid crystal display or an organic EL display, and a drive circuit that drives the display device to display an image (none is shown). The video processing unit 8 reconstructs the original video from the video signal (video data) output from the transmission processing unit 2 and causes the display unit 9 to display the reconstructed video.

  The dwelling unit control unit 1 includes hardware such as a CPU and a memory, and various programs (software) executed by the CPU. The operation input accepting unit 10 has an input device such as a touch panel or a push button switch, accepts various operation inputs by operating the input device, and sends operation signals corresponding to each operation input to the dwelling unit control unit 1. Output to. For example, a response button (not shown) is provided on the front of the housing of the dwelling unit A. When this response button is pressed, an operation input is received by the operation input receiving unit 10 and a response operation signal is output. Is done. In the dwelling unit control unit 1, when an operation signal is input from the operation input receiving unit 10, processing corresponding to each operation signal is executed.

  The transmission processing unit 2 performs packet transmission with the trunk distribution device B and other dwelling units A via the dwelling unit trunk lines LS1 and LS2 and the dwelling unit line LA. The transmission processing unit 2 divides the control signal (control data) created by the dwelling unit control unit 1 to create a packet (control packet), and the transmission voice signal (transmission) also created by the call processing unit 3 The voice data is divided to create a packet (voice packet). Further, the transmission processing unit 2 encodes the control packet and the voice packet, converts (modulates) the encoded bit string into an electric signal, and sends the encoded signal to the main trunk lines LS1 and LS2. Also, the transmission processing unit 2 converts (demodulates) the electric signal flowing from the dwelling trunk lines LS1 and LS2 into the bit string and decodes the packet (voice packet, control packet, video packet) from the demodulated bit string. The transmission processing unit 2 discards the packet if the address of the decrypted packet does not match its own address (address of the dwelling unit A), and if the address matches, it is included in the data field of the packet. If the data is video data (video signal), it is output to the video processing unit 8, if it is control data (control signal), it is output to the dwell unit control unit 1, and if it is audio data (voice signal), it is output to the call processing unit 3. To do. However, if the address of the packet is a multicast address or a broadcast address, the transmission processing unit 2 processes the packet without discarding it even if it does not match its own address.

  By the way, in packet transmission between the transmission processing unit 2 of the dwelling unit A and the second transmission processing unit 32 of the trunk distribution device B, packet transmission of the multicarrier adaptive modulation method is performed as in the conventional example. Therefore, as described in the prior art, before the dwelling unit A transmits a transmission signal, a packet (request packet) requesting channel estimation is transmitted to the trunk distribution device B, and then the result of the channel estimation processing is notified. It is necessary to receive a packet (reply packet). However, since the plurality of dwelling unit trunk lines LS1, LS2 are connected to the second transmission processing unit 32 of the same trunk distribution apparatus B via the transmission amplifiers TA1, TA2 or the reception amplifiers RA1, RA having directionality, Even if the carrier sense is executed, the carrier of the transmission signal transmitted by the other party cannot be detected between the dwelling units A branched and connected to the different dwelling unit trunk lines LS1 and LS2. Therefore, as described in the related art, when the collision of request packets frequently occurs in the trunk distribution apparatus B, there is a possibility that the channel estimation process is not performed normally and communication cannot be started.

  Therefore, in this embodiment, before the dwelling unit A requests the main line distribution device B to perform channel estimation, a transmission signal (channel estimation start notification packet) for notifying the start of channel estimation is transmitted, and the main line distribution device B A transmission signal (channel estimation start response packet) for responding to the notification is returned.

  Hereafter, with reference to the sequence diagram of FIG. 2, the operation | movement at the time of transmitting a transmission signal from the dwelling unit A branched and connected to the dwelling unit trunk line LS1 is demonstrated. In FIG. 2, the upper side of the time axis represents transmission from the dwelling unit A to the main line distribution device B, and the lower side of the time axis represents return from the main line distribution device B to the dwelling unit A.

  First, in the dwelling unit A, after the transmission processing unit 2 that has received the channel estimation start notification packet from the dwelling unit control unit 1 performs carrier sense, the channel estimation start notification packet is transmitted via the dwelling unit line LA. At this time, the transmission processing unit 2 transmits the data by multicast or broadcast so that a terminal (other dwelling unit A) other than the main line distribution device B can receive the data. Further, the transmission processing unit 2 modulates and modulates the channel estimation start notification packet with a modulation method having a relatively low multilevel modulation degree (for example, BPSK <binary phase shift keying> method) so that the packet can be received reliably. Transmit the transmission signal n times (n ≧ 2). Thereby, the main line distribution apparatus B and other dwelling units A can reliably receive the channel estimation start notification packet.

  The transmission signal transmitted from the dwelling unit A is received by the second transmission processing unit 32 of the trunk distribution device B. When receiving the channel estimation start notification packet from the transmission signal received by the second transmission processing unit 32, the control unit 30 of the trunk distribution apparatus B immediately creates a response packet (channel estimation start response packet) to the channel estimation start notification. To the second transmission processing unit 32. The second transmission processing unit 32 modulates the channel estimation start response packet with a modulation method having a relatively low multilevel modulation degree (for example, BPSK <binary phase shift keying> method), and multicast or broadcast the modulated transmission signal. And send n times continuously.

  When the transmission signal returned from the trunk distribution device B is received by the dwelling unit A that is the transmission source of the channel estimation start notification packet, the dwell unit control unit 1 of the dwelling unit A requests channel estimation processing. A request packet (request packet) is created and output to the transmission processing unit 2. The transmission processing unit 2 transmits a request packet to the trunk distribution apparatus B by a transmission signal digitally modulated using all subcarriers.

  In the trunk distribution device B, when the request packet transmitted from the dwelling unit A is received, the S / N ratio for each subcarrier when the control unit 30 receives the request packet is calculated according to the channel estimation request and is calculated. Whether or not each subcarrier can be used is determined based on the S / N ratio. Further, the control unit 30 of the main line distributor B determines a digital modulation method (multi-level modulation degree) based on the S / N ratio of all sub-carriers determined to be usable, and uses the sub-carrier and multi-level to be used. A packet including the modulation degree information (reply packet) is created and output to the second transmission processing unit 32. The second transmission processing unit 32 returns a transmission signal obtained by digitally modulating the reply packet to the requesting unit A.

  In the dwelling unit A, when the transmission packet is received by the transmission processing unit 2 in the transmission unit 2, the dwelling unit control unit 1 determines the subcarrier and the multi-level modulation degree based on the information included in the reply packet. Then, the transmission processing unit 2 of the dwelling unit A transmits a transmission signal obtained by digitally modulating the packet with the subcarrier and the multilevel modulation degree determined by the dwelling unit control unit 1.

  Here, the channel estimation start notification packet includes the address of the trunk distribution device B that is the channel estimation start notification destination, and the channel estimation start response packet includes the address of the dwelling unit A that is the channel estimation start notification source. It is included. Therefore, when the transmission processing unit 2 receives the channel estimation start notification packet and the channel estimation start response packet in the dwelling unit A other than the dwelling unit A that is the notification source of the channel estimation start, a predetermined scheduled time elapses. A transmission signal is not transmitted from the transmission processing unit 2. The scheduled time is the time until the channel estimation process based on the channel estimation request is completed.

  Thus, the shorter the packet length of the channel estimation start notification packet and the channel estimation start response packet (the time length of the transmission signal in which each packet is modulated) is shorter than the packet length of the request packet and the reply packet, The probability of success will increase. This is because the carrier cannot be detected between the dwelling unit A that is branched and connected to one dwelling unit trunk line LS1 and the dwelling unit A that is branched and connected to the other dwelling unit trunk line LS2. As the packet length of the transmission signal transmitted from the dwelling unit A that is branched and connected to the transmission unit B increases, the transmission signal transmitted from the dwelling unit A that is branched and connected to the other dwelling unit trunk line LS2 collides with the main line distributor B. This is because the probability increases.

  As described above, according to the present embodiment, another dwelling unit from when the channel estimation start notification packet is transmitted from the dwelling unit A to when the reply packet is returned from the trunk distribution device B to the dwelling unit A. The probability that a transmission signal is transmitted from A will be lower than before. As a result, it is possible to increase the probability that channel estimation is performed while suppressing collision of transmission signals.

  By the way, it is preferable not to fix the time (waiting time) for which the dwelling units A other than the dwelling unit A that is the notification source of the channel estimation start without waiting for transmission of transmission signals. This is because the time from the notification of the start of channel estimation to the completion of the channel estimation process based on the channel estimation request (hereinafter referred to as “channel estimation processing time”) is the transmission path at that time (the dwelling trunks LS1, LS2 This is because there is a high possibility of fluctuations depending on the communication load.

  Therefore, the dwelling unit A transmits the channel estimation start notification packet including the channel estimation processing time information T (the scheduled time), and the trunk distributor B includes the channel estimation processing time information T in the channel estimation start response packet. You may make it transmit including the information T 'of the time which deducted predetermined progress prediction time. Further, the dwell unit control unit 1 of the dwelling unit A and the control unit 30 of the main line distribution device B count the amount (number) of packets flowing through the dwell unit main lines LS1 and LS2 per unit time, and the counted packet amount (communication load) It is preferable to adjust the scheduled time according to (). For example, if the amount of packets per unit time is large (the communication load is high), it can be determined that there is a high probability that a plurality of dwelling units A will simultaneously request channel estimation, so if the scheduled time is made longer than usual, Good. On the other hand, when the amount of packets per unit time is small (communication load is low), it can be determined that there is a low probability that a plurality of dwelling units A will simultaneously request channel estimation, so the scheduled time can be made shorter than usual. That's fine.

  Then, the dwell unit control unit 1 of the dwelling unit A other than the dwelling unit A that is the channel estimation start notification source obtains the channel estimation processing time information (the scheduled time) from the channel estimation start notification packet or the channel estimation start response packet. The transmission signal is not transmitted until the scheduled time elapses. Therefore, the scheduled time (standby time) is adjusted to an appropriate length according to the communication load of the dwelling unit trunk lines LS1 and LS2, so that the channel estimation process can be performed efficiently.

A Unit B B Trunk distributor
C1, C2 Lobby intercom (common equipment)
LC1 and LC2 common use trunk line
LS1, LS2 Sumitomo trunk line

Claims (7)

A trunk distribution device that distributes a transmission signal transmitted from a shared device installed in a common entrance via a shared trunk to a plurality of residential trunks, and a plurality of dwelling units that are branched and connected to the plurality of residential trunks, respectively. The dwell unit transmits a transmission signal for notifying the start of channel estimation before requesting the channel estimation of multicarrier adaptive modulation to the trunk distribution device, and the trunk distribution device An intercom system for collective housing, characterized by multicasting or broadcasting a transmission signal for responding to   The time length of a transmission signal for notifying the start of channel estimation and the time length of a transmission signal for responding to the notification are shorter than the time length of the transmission signal for the channel estimation request. The intercom system for apartment buildings described.   The said dwelling unit multicasts or broadcasts a transmission signal for notifying the channel estimation start, and the trunk distribution device multicasts or broadcasts a transmission signal for a response to the notification. Or the intercom system for apartment houses of 2 description.   The dwell unit transmits the channel estimation start notification using a transmission signal modulated by a modulation method having a relatively low multi-level modulation degree, and the trunk distribution apparatus relatively multi-level modulates a response to the notification. The intercom system for an apartment house according to any one of claims 1 to 3, wherein a reply is made with a transmission signal modulated by a low modulation method.   5. The dwell unit continuously transmits a transmission signal for notifying the start of channel estimation, and the trunk distribution device continuously transmits a transmission signal for a response to the notification. The intercom system for collective housing as described in any one of the above.   The dwell unit transmits a transmission signal for notifying the start of channel estimation, including a scheduled time until the channel estimation process based on the channel estimation request is completed, and the trunk line distribution device transmits the channel estimation process. The intercom system for collective housing according to any one of claims 1 to 5, wherein a transmission signal for responding to the notification including a scheduled time until completion of the transmission is transmitted. Multi-carrier adaptation from a plurality of dwelling units that distribute transmission signals transmitted from a common unit installed in a common entrance via a common unit trunk line to a plurality of dwelling unit trunk lines and branch connections to the plurality of dwelling unit trunk lines. When the transmission signal for notifying the start of the channel estimation is received from the dwelling unit before the channel estimation request is received, a response to the notification A trunk distribution device configured to multicast or broadcast a transmission signal for

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