A group call voice processing device suitable for satellite communication

Abstract

The application discloses a group route voice processing device suitable for satellite communication and relates to the field of satellite communication. The device comprises a bottom plate module, a four-wire operational amplifier interface module, a PCM coding module, a 16-way analog two-wire interface, a plurality of user modules, an ARM main control module, an E1 interface module, a signaling adaptation module, a digital logic processing module, an echo cancellation module, a G729 signaling module and a power module. The device fully considers the characteristics of long transmission time delay, limited channel resources and multiple voice service types of satellite communication, adopts digital logic comprehensive processing plus a main control module to perform protocol processing, echo cancellation and logic dynamic control, supports four-wire service, multi-way analog two-wire voice and E1 voice three main voice services, has 3-way dynamically configurable PCM voice data, IP interface remote control and control interface based on CAN2.0, and has the characteristics of supporting all voice types, high integration, flexible voice configuration and rich control interface.

Description

Technical Field

[0001] This invention relates to the field of satellite communication, and in particular to a multi-channel voice processing device suitable for satellite communication, which can be used as a device for accessing and processing various types of voice in a satellite communication system. Background Technology

[0002] Voice communication in satellite communication systems is characterized by a variety of service modes and complex application scenarios. Traditional satellite communication voice processing devices generally include three types: one is analog two-wire voice service, used to connect telephones or PBXs for point-to-point voice dialing communication; the second is four-wire voice service supporting trunking services, used for broadcast or multicast network voice communication between multiple users; and the third is digital E1 voice service, used to support the access and switching functions of group data and voice.

[0003] Because the three existing voice services use different access methods, traditional voice processing devices typically require external multiplexing equipment and satellite communication channel equipment, supporting only a single voice service communication mode. Traditional voice processing devices suffer from drawbacks such as a single voice service mode, weak interoperability between voice processing devices of different modes, low efficiency of dynamic switching of group voice channels, complex protocol design between voice processing devices and satellite communication devices, and low utilization of satellite communication channels. Summary of the Invention

[0004] In view of this, the present invention proposes a group voice processing device suitable for satellite communication. The present invention features support for multiple voice service types, comprehensive functionality, rich interfaces, and high reliability. It can realize various types of group voice processing and can be efficiently integrated with existing satellite communication devices, thus possessing broad application prospects.

[0005] The technical solution adopted in this invention is as follows:

[0006] A group voice processing device suitable for satellite communication includes a baseboard module J, a four-wire operational amplifier interface module I, a PCM encoding module B, a 16-channel analog two-wire interface, multiple user modules C1 to CN, an ARM main control module D, an E1 interface module F, a signaling adapter module E, a digital logic processing module A, an echo cancellation module K, a G729 signaling module L, and a power supply module H.

[0007] Specifically, pin 1 of the digital logic processing module is connected to pin A of the baseboard module to transmit voice data from three PCM buses; pin 11 of the digital logic processing module is connected to pin 1 of the signaling adapter module to transmit protocol information in HDLC frame format; pin 12 of the digital logic processing module is connected to pin 2 of the signaling adapter module to transmit PCM bus voice data; pin 2 of the digital logic processing module is connected to pin 2 of the PCM encoding module, which is connected to the baseboard module via a four-wire operational amplifier interface module to transmit one four-wire command voice data; pin 13 of the digital logic processing module is connected to pin 3 of the echo cancellation module to transmit GPIO configuration information; and pins 14 and 15 of the digital logic processing module are connected to pins 2 and 3 of the echo cancellation module K to transmit PCM voice data before and after cancellation.

[0008] Pin 3 of the signaling adapter module is connected to pin 1 of the E1 interface module to transmit PCM voice data. Pin 2 of the E1 interface module is connected to pin F of the baseboard module to provide digital E1 voice signals to the outside.

[0009] Pin 1 of the G729 signaling module is connected to pin 17 of the digital logic processing module for transmitting PCM voice data; pin 2 of the G729 signaling module is connected to pin 16 of the digital logic processing module for transmitting TTL level serial asynchronous data.

[0010] Pin 1 of the power module is connected to an external +12V DC input power supply, while pins 2, 3, and 4 are +5V, +3.3V, and +1.8V power outputs, respectively, used to power other modules.

[0011] Furthermore, the user module has 16 channels, which are in parallel. Pin 1 of the user module is connected to the digital voice logic processing module for transmitting SPI control signals. Pin 2 of the user module is connected to the digital voice logic processing module for transmitting PCM voice data in time slots. Pin 3 of the user module is directly connected to the corresponding analog two-wire interface for transmitting the analog two-wire TIP and RING signals. The analog two-wire interface module is connected to the baseboard module J for transmitting 16 channels of analog two-wire voice data.

[0012] Furthermore, pin 1 of the ARM main control module is connected to pin 8 of the digital logic processing module to transmit a 32-bit DATA bus; pin 2 of the ARM main control module is connected to pin 9 of the digital logic processing module to transmit control bus signals; and pin 3 of the ARM main control module is connected to pin 10 of the digital logic processing module to transmit a 22-bit ADDR address bus signal.

[0013] Pin 5 of the ARM main control module is connected to pin 1 of the CAN port driver module for transmitting CAN2.0 bus data; pin 2 of the CAN port driver module is connected to pin E of the baseboard module for transmitting CAN bus control signals; pin 6 of the ARM main control module is connected to pin 1 of the network port driver module for converting ARM bus data into IP data; pin 2 of the network port driver module is connected to pin D of the baseboard module for transmitting 100Mbps Ethernet port data.

[0014] Furthermore, the digital logic processing module internally implements a real-time PCM voice data exchange network. This exchange network uses the FPGA's on-chip BRAM resources as the PCM voice data exchange table. Through receiving and transmitting logic state machines, combined with the PCM voice data exchange management table, it controls the writing and reading of data within the PCM voice data exchange table. In addition, the digital logic processing module provides an upper-level monitoring interface to the ARM main control module, allowing for the exchange of any PCM time slot with any corresponding PCM time slot according to the needs of the upper-level user. The real-time PCM voice data exchange network is used to perform the following steps:

[0015] 1) Receive the time slot switching configuration from the ARM main control module, initialize the PCM voice data switching management table according to the configuration. If there is no time slot switching configuration, the PCM voice data switching management table is initialized by default without switching any time slots, and then proceed to step 2).

[0016] 2) Receive PCM data from one end of the PCM interface. The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 3).

[0017] 3) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address, and sends the data to the corresponding PCM interface, then proceeds to step 4);

[0018] 4) Receive PCM data from the other end PCM interface. The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 5).

[0019] 5) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange management table, and sends the data to the peer PCM interface to complete the corresponding time slot exchange. Then it proceeds to step 2). If the time slot exchange configuration of the superior user changes, it restarts from step 1).

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention is a multifunctional group voice access and processing device that supports various voice services, mainly including four-wire trunked voice, 16-channel analog two-wire voice, and digital E1 voice. The 16-channel analog voice, four-wire trunked voice, and digital E1 voice can be dynamically scheduled and flexibly allocated, outputting and carrying to a 3-channel PCM voice bus for integration. The analog two-wire voice supports both user and trunk modes, facilitating direct access to telephones or PBXs; the E1 voice supports configurable SS7 signaling TUP and ISUP modes, achieving efficient integration of SS7 E1 signaling and satellite channel communication protocols.

[0022] 2. This invention fully considers the physical characteristics of satellite communication channels and introduces a callback cancellation module and a G729 signaling module suitable for satellite communication. The callback cancellation module solves the problem of voice echo caused by the delay when group voice is transmitted through synchronous satellite. The signal tone detection, generation and insertion of the G729 signaling module solves the problem of dynamic processing of signal tone under different voice service types, realizing an independent and complete closed loop for voice services.

[0023] 3. This invention designs a digital logic processing module and an ARM main control module as the core components of this device. A high-capacity, interface-rich FPGA digital logic processing module is selected. Through custom-developed digital logic software, the dynamic configuration of the protocols, interfaces, and PCM data of each module is realized at the physical level. The main control software runs on the ARM main control module, realizing the comprehensive management function of this device at the application layer. At the same time, it expands the Ethernet port and CAN interface, which is conducive to standard information interaction with external station control and terminal main control.

[0024] 4. This invention adopts a modular approach, with each functional module supported by a base plate module. The coupling between functional modules and between functional modules and the base plate module is low, with clear interfaces, reasonable logical partitioning, and excellent electrical characteristics. This device uses a standardized CPCI component interface, is equipped with an aluminum alloy cold plate and fastening devices, has a simple overall structure, is easy to assemble and disassemble, and can be easily integrated into a satellite communication terminal, achieving integrated integration of this device and satellite communication equipment.

[0025] 5. This invention has a high degree of integration, small size, light weight, low power consumption, stable and reliable performance. The entire device weighs only 1.3kg and can adapt to harsh environments from -25℃ to 65℃. It also has good three-proof and electromagnetic compatibility characteristics, and has strong promotion and application value. Attached Figure Description

[0026] Figure 1 This is a block diagram illustrating the principle of the present invention. Detailed Implementation

[0027] Reference Figure 1 A group voice processing device suitable for satellite communication includes a baseboard module J, a four-wire operational amplifier interface module I, a PCM encoding module B, a 16-channel analog two-wire interface, user modules C1-CN, an ARM main control module D, an E1 interface module F, a signaling adapter module E, a digital logic processing module A, an echo cancellation module K, a G729 signaling module L, and a power supply module H. Figure 1 This is a schematic block diagram of the device. The embodiments are as follows: Figure 1 Connecting lines.

[0028] Among them, the digital logic processing module A is a field-programmable gate array (FPGA), chip model FPGAEP3C120F780I7N, which has the advantages of multiple digital logic interfaces, strong processing capabilities, and dynamic software configuration and loading; pin 1 of the digital logic processing module A is connected to pin A of the baseboard module J, and is used to transmit voice data of 3 channels of PCM bus, each channel has a data information rate of 2.048MHz, and the 32 time slots of data inside the PCM bus are dynamically configurable;

[0029] Pin 11 of digital logic processing module A is connected to pin 1 of signaling adapter module E to transmit protocol information in HDLC frame format; pin 12 of digital logic processing module A is connected to pin 2 of signaling adapter module E to transmit PCM bus voice data.

[0030] Pin 2 of digital logic processing module A is connected to pin 2 of four-wire operational amplifier and encoding module B, used to transmit one channel of four-wire command voice data, occupying one time slot in the PCM bus, with an information rate of 64kbps; the four-wire operational amplifier and encoding module B consists of two parts: a PMC codec module and a four-wire operational amplifier interface module. The PMC codec module uses the W680310WG chip to realize the conversion function from two-wire to PCM voice; the four-wire operational amplifier interface is composed of operational amplifier circuits, and the operational amplifier chip is LM158AD, realizing the conversion from four-wire VIN_P, VIN_N, VOUT_P, VOUT_N to two-wire VIN and VOUT;

[0031] Pin 13 of digital logic processing module A is connected to pin 3 of echo cancellation module K to transmit GPIO configuration information and load the digital logic programming submodule software to configure parameters such as the working mode, cancellation delay, and encoding standard of echo cancellation module K. Pins 14 and 15 of digital logic processing module A are connected to pins 2 and 3 of echo cancellation module K to transmit PCM voice data before and after cancellation. The echo cancellation module K chip model is ZL50232 / QCC, which is a 32-channel voice group echo canceller that can provide 32 channels of 64ms or 16 channels of 128ms in accordance with ITU-T G.165 and G.168 standards.

[0032] Signaling adapter module E is an onboard communication module with a real-time embedded processor as its core. The CPU chip is the high-performance MPC8280CVVUPEA from the PowerPC series; the SDRAM chip is MT48LC8M16A2P-6AIT; the FLASH chip is JS28F320J3F75; the embedded real-time operating system is Vxworks, which implements digital E1 data, SS7 signaling processing, and dedicated satellite channel voice protocol processing and data conversion functions through the loading of dedicated software; Signaling adapter module E is equipped with SEM-140-02-03.0-HDA surface mount connector, and the dimensions of a single module are 95mm × 70mm × 12mm (length × width × height).

[0033] The signaling adapter module's E3 pin is connected to pin 1 of the E1 interface module F to transmit PCM voice data. The E1 interface module F's pin 2 is connected to pin F of the baseboard module J to provide digital E1 voice signals. The E1 interface module uses the DS21348 chip to convert PCM data into E1 differential data. The baseboard module J's F pin has E1 transmit / receive differential E1_R+, E1_R-, E1_T+, and E1_T-.

[0034] User modules C1 and C_N are multi-channel analog two-wire voice modules, currently configured with 16 channels. Taking user module C1 as an example, pin 1 of user module C1 is connected to pin 4 of digital voice logic processing module A for transmitting SPI control signals; pin 2 of user module C1 is connected to pin 5 of digital voice logic processing module A for transmitting PCM voice data in time slots. The PCM time slots and data synthesis for each voice channel are completed within digital logic processing module A. The user module model is the domestic MYP2608, packaged in DIP-27, with individual module dimensions of 60mm × 25.4mm × 10mm (length × width × height). The SPI control bus is used to configure the user module for off-hook / on-hook, ring detection and generation, polarity detection, 2 / 4-wire conversion, and encoding / decoding functions. The S / O control signal is used for switching the user module's operating mode. When S / O is set to 0, the user module operates in FXS user mode; when S / O is set to 1, the user module operates in trunk mode.

[0035] Pin 3 of user module C1 is directly connected to the analog two-wire interface, model JK250-120U, which provides surge protection and voltage protection, and transmits analog two-wire TIP and RING signals. Analog two-wire interface module C1 to CN are connected to pins C1 to CN of baseboard module J, and transmit 16 channels of analog two-wire voice signals through C1 to CN of baseboard module J, which can connect to 16 telephone stand-alone units or voice-controlled switching equipment.

[0036] The ARM main control module D uses the PXA270 processing module based on the XCALE architecture. Pin 1 of the ARM main control module D is connected to pin 8 of the digital logic processing module A to transmit a 32-bit DATA bus. Pin 2 of the ARM main control module D is connected to pin 9 of the digital logic processing module A to transmit control signals, including write enable (WE), read enable (OE), chip select (CS_1 to CS_5), and wait control (WAIT). Pin 3 of the ARM main control module D is connected to pin 10 of the digital logic processing module A to transmit a 22-bit ADDR address bus signal.

[0037] Pin 5 of the ARM main control module D is connected to pin 1 of the CAN port driver module G for transmitting CAN2.0 bus data. The chip model of the CAN port driver module G is TJA1050. Pin 2 of the CAN port driver module G is connected to pin E of the baseboard module J for transmitting CAN bus control and for managing and querying the ARM main control module.

[0038] Pin 6 of the ARM main control module D is connected to pin 1 of the network port driver module H to convert ARM bus data into IP data. The network port driver module includes a DM9000AE network driver chip and an H1102NL network transformer. Pin 2 of the network port driver module is connected to pin D of the baseboard module J for transmitting 100 Mbps Ethernet data that conforms to the IEEE 802.3 standard.

[0039] Pin 1 of the G729 signaling module L is connected to pin 17 of the digital logic processing module A for transmitting PCM voice data; pin 2 of the G729 signaling module L is connected to pin 16 of the digital logic processing module A for transmitting TTL level serial asynchronous data; the G729 signaling module L uses TMS320VC5509A, with a hardware module size of 28mm×36mm. Each side of the module has a row of 6100S-1x14PG-3.2 type single-row round hole sockets. It uses DSP algorithms to support the generation and detection of composite G.729 protocol dial tones, ringback tones, busy tones, and other signal tones, and has the advantages of fast processing speed and low power consumption.

[0040] Power module H is a miniaturized, high-efficiency series of switching power supplies that converts the +12V DC input power into +5V, +3.3V, and +1.8V output power to provide DC power to various modules, including user module C, ARM main control module, digital logic processing module A, and signaling adapter module E. The series of power chips are PTN04050AAH, and the linear regulators are LT1764EQ-3.3V and LT1764EQ-1.8V. A π-type filter network is added to the +12V input of pin 1 of power module H to ensure the stability of the input power.

[0041] The digital logic processing module internally implements a real-time PCM voice data exchange network (external interface is pins 1, 2, 5, and 7 of the digital logic processing module). This exchange network uses the FPGA's on-chip BRAM resources as the PCM voice data exchange table. Through receiving and transmitting logic state machines, combined with the PCM voice data exchange management table, it controls the writing and reading of data within the PCM voice data exchange table, offering advantages such as high speed and low latency, thus ensuring the continuity and integrity of the PCM voice data. Furthermore, the digital logic processing module provides an upper-level monitoring interface to the ARM main control module through pins 8, 9, and 10. This interface allows for the exchange of any PCM time slot with any corresponding PCM time slot according to the needs of the upper-level user. During use, the voice is clear and indistinguishable without any lag. The real-time PCM voice data exchange network is used to execute the following steps:

[0042] 1) Receive the time slot switching configuration from the ARM main control module through pins 8, 9, and 10, and initialize the PCM voice data exchange management table according to the configuration. If there is no time slot switching configuration, the PCM voice data exchange management table is initialized by default without switching any time slots, and then proceed to step 2).

[0043] 2) Receive PCM data from one end of the PCM interface (pins 1, 2, 5, 7). The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 3).

[0044] 3) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address, and sends the data to the corresponding PCM interface (pins 1, 2, 5, 7). Then proceed to step 4).

[0045] 4) Receive PCM data from the other end PCM interface (pins 1, 2, 5, 7). The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 5).

[0046] 5) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange management table, and sends the data to the PCM interface of the peer end (pins 1, 2, 5, 7) to complete the corresponding time slot exchange. After that, it proceeds to step 2). If the time slot exchange configuration of the superior user changes, it restarts from step 1).

[0047] The installation structure of this device is as follows: The group voice processing device uses baseboard module J as the base plate, and each functional module is carried on baseboard module J. The baseboard module is a CPCI architecture PCB printed circuit board with dimensions of length × width × height = 330mm × 143mm × 32mm. The height of the front and back sides of the printed circuit board components does not exceed 25mm. Baseboard module J uses CPCI socket assembly, with connector models H2A110FMD, H2B110FMD, H2B95FMD, H2A110FMD, and H2B110FMD. Baseboard module J and each functional module constitute the basic functions of the group voice processing device. A heat dissipation support cold plate is configured on the entire module. The cold plate is made of aluminum alloy, which is lightweight and has good conductivity and electromagnetic shielding performance. The upper two ends of the cold plate are equipped with locking handles to facilitate the installation and unloading of this device. The above modules and components are assembled together to form this device.

[0048] This invention fully considers the characteristics of satellite communication, such as transmission delay, limited channel resources, and diverse voice service types. It employs digital logic integrated processing plus a main control module for protocol processing, echo cancellation, and dynamic logic control. It supports three main voice services: four-line service, multiple analog two-line voice channels, and E1 voice. Externally, it features three dynamically configurable PCM voice data channels, IP interface remote control, and a CAN2.0-based control interface. This invention can realize the access processing of multiple analog voice channels, digital voice channels, and four-line service voice channels. It features comprehensive voice type support, high integration, flexible voice configuration, and rich control interfaces, making it particularly suitable for various types of multiple-channel voice access processing in the satellite communication field.

Claims

1. A group voice processing device suitable for satellite communication, characterized in that, It includes baseboard module J, four-wire operational amplifier interface module I, PCM encoding module B, 16-channel analog two-wire interface, multiple user modules C1~CN, ARM main control module D, E1 interface module F, signaling adapter module E, digital logic processing module A, echo cancellation module K, G729 signaling module L, and power supply module H; Specifically, pin 1 of the digital logic processing module is connected to pin A of the baseboard module to transmit voice data from three PCM buses; pin 11 of the digital logic processing module is connected to pin 1 of the signaling adapter module to transmit protocol information in the HDLC frame format; pin 12 of the digital logic processing module is connected to pin 2 of the signaling adapter module to transmit PCM bus voice data; pin 2 of the digital logic processing module is connected to pin 2 of the PCM encoding module, which is connected to the baseboard module via a four-wire operational amplifier interface module to transmit one four-wire command voice data; pin 13 of the digital logic processing module is connected to pin 3 of the echo cancellation module to transmit GPIO configuration information; and pins 14 and 15 of the digital logic processing module are connected to pins 2 and 3 of the echo cancellation module K to transmit PCM voice data before and after cancellation. Pin 3 of the signaling adapter module is connected to pin 1 of the E1 interface module to transmit PCM voice data, and pin 2 of the E1 interface module is connected to pin F of the baseboard module to provide digital E1 voice signals to the outside. Pin 1 of the G729 signaling module is connected to pin 17 of the digital logic processing module for transmitting PCM voice data; pin 2 of the G729 signaling module is connected to pin 16 of the digital logic processing module for transmitting TTL level serial asynchronous data. Pin 1 of the power module is connected to an external +12V DC input power supply, while pins 2, 3, and 4 are +5V, +3.3V, and +1.8V power outputs, respectively, used to power other modules.

2. The group voice processing device for satellite communication according to claim 1, characterized in that, The user module has 16 channels, which are in parallel. Pin 1 of the user module is connected to the digital voice logic processing module and is used to transmit SPI control signals. Pin 2 of the user module is connected to the digital voice logic processing module and is used to transmit PCM voice data in time slots. Pin 3 of the user module is directly connected to the corresponding analog two-wire interface and transmits the analog two-wire TIP and RING signals. The 16-channel analog two-wire interface is connected to the baseboard module J to transmit 16 channels of analog two-wire voice data.

3. A group voice processing device suitable for satellite communication according to claim 1, characterized in that, Pin 1 of the ARM main control module is connected to pin 8 of the digital logic processing module to transmit a 32-bit DATA bus; pin 2 of the ARM main control module is connected to pin 9 of the digital logic processing module to transmit control bus signals; pin 3 of the ARM main control module is connected to pin 10 of the digital logic processing module to transmit a 22-bit ADDR address bus signal. Pin 5 of the ARM main control module is connected to pin 1 of the CAN port driver module for transmitting CAN2.0 bus data; Pin 2 of the CAN port driver module is connected to pin E of the baseboard module to transmit control signals for the CAN bus. Pin 6 of the ARM main control module is connected to pin 1 of the network port driver module to convert ARM bus data into IP data; Pin 2 of the network port driver module connects to pin D of the baseboard module for transmitting 100 Mbps Ethernet data.

4. A group voice processing device suitable for satellite communication according to claim 1, characterized in that, The digital logic processing module internally implements a real-time PCM voice data exchange network. This network uses the FPGA's on-chip BRAM resources as the PCM voice data exchange table. It controls the writing and reading of data within the PCM voice data exchange table through receiving and transmitting logic state machines, combined with the PCM voice data exchange management table. Furthermore, the digital logic processing module provides an upper-level monitoring interface to the ARM main control module, allowing for the exchange of any PCM time slot with any corresponding PCM time slot according to the needs of the upper-level user. The real-time PCM voice data exchange network is used to perform the following steps: 1) Receive the time slot switching configuration from the ARM main control module, and initialize the PCM voice data exchange management table according to the configuration. If there is no time slot switching configuration, the PCM voice data exchange management table is initialized by default without switching any time slots, and then proceed to step 2). 2) Receive PCM data from one PCM interface. The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 3). 3) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address, and sends the data to the corresponding PCM interface, then proceeds to step 4). 4) Receive PCM data from the other end of the PCM interface. The receiving logic state machine writes the PCM voice data into the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange table, and then proceeds to step 5). 5) The sending logic state machine reads data from the corresponding address in the PCM voice data exchange management table according to the address in the PCM voice data exchange management table, and sends the data to the peer PCM interface to complete the corresponding time slot exchange. After that, it proceeds to step 2). If the time slot exchange configuration of the superior user changes, it restarts from step 1).

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