KR100258148B1 - Method of, inter-cell bearer handover in dect wireless pabx - Google Patents

Abstract

PURPOSE: A method for handling bearer hand over between base stations of DECT(Digital European Cordless Telephone) type wireless exchanger is provided to extend user's mobility to broader extent by performing hand over handling without any disconnection of a call when a user moves from a base station to another base station. CONSTITUTION: MBC-IE-TBC-HANDOVER-REQUEST message is checked whether the message is received to the second base station device area while a DECT terminal is communicating with the first base station device. MBC task management table is checked whether an identical PMID is present when MBC-IE-TBC-HANDOVER-REQUEST is received. The corresponding bearer is released by transmitting MFP-MBC-BEARER-RELEASE message when none of MBC task management table has an identical PMID. A base station device of a principle bearer, which is stored in the MBC management table is compared with a base station device whether it is identical by sending MBC-IE-TBC-HANDOVER-REQUEST message, when an identical PMID is present at the MBC task management table. If the base station device of a principle bearer and the base station device does not match, intra-cell barter hand over is processed. If the base station device of a principle bearer and the base station device matches, MFP-LLME-HANDOVER-IND is generated to check whether a hand over is possible. If the hand over is impossible, the corresponding bearer is released by receiving MFP-MBC-TBC-BEARER-RELEASE message from the second base station. If the hand over is possible, MFP-MBC-BEARER-GRANT message and MFP-ME-CONNECTION-BCH is transmitted to the second base station to perform a bearer connection and B-channel connection. If the connection is completed, MBC-IE-TBC-BEARER-ESTABLISHED message indicating that the hand over bearer is established is transmitted. HANDER-REQ message is sent out to an exchanger so that the B-channel becomes converted.

Description

Method of handling bearer handover between base stations in a DECT type wireless switch {METHOD OF, INTER-CELL BEARER HANDOVER IN DECT WIRELESS PABX}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearer handover processing method in a DECT (DECT) wireless private exchange system or a key phone system, and in particular, an inter-cell bearer hand that enables a call even when a terminal moves between base stations. It's about overhanding.

The first cordless telephone systems are cordless telephones such as the CTO and CT1. Since the CTO and CT1 wireless telephones use an analog method, it is not easy to guarantee call quality or reliability of information transmission between a base station and a portable device. The CT2, a digital wireless telephone of the CAI (Common Air Interface) standard, was introduced to improve the reliability of call quality and information transmission of wireless telephone systems. The CT2 radiotelephone provides wireless call service according to frequency division multiple access (FDMA) / time division duplex (TDD). However, even when using CT2, there is a problem in that it is not easy to provide an effective handover, and a coupling divider is required when using a single antenna. On the other hand, DECT is another digital wireless telephone technology introduced to improve the reliability of the call quality and information transmission of the wireless telephone system. DECT is a wireless access method standardized by the European Telecommunications Standards Institute (ETSI), and provides a wireless call service according to time division multiple access (TDMA) / TDD. DECT (The Digital European Cordless Telephone) is described in detail in ETS 300 175-1 to 175-9. Patents related to DECT include EP 0 486 089 (Efficient Carrier Scanning Method in Terminal), EP 0 445 887 (Method for Optimizing Beacon Message Transmission at Base Station), EP 0 587 225 (Method for Data Transmission to DECT Communication Channel), etc. There is this. As described above, many techniques related to DECT have been disclosed. However, there is no description on how to handle inter-cell bearer handovers occurring between base stations in the premises wireless system. Especially, the conventional DECT implementation method is residential. That is, in the case of a system used alone, there is a problem in that a service range is limited when only intra-cell bearer handover is compensated (change of DECT slot) because only one cell is configured.

Accordingly, an object of the present invention is to accommodate a plurality of base stations in the case of a deck type on-site wireless telephone system, so that a bearer handover process occurring between base stations in the on-premises wireless telephone system can be performed by using another scheme such as switching of voice lines. It is to provide a method that can compensate for the expansion of the mobility to a wider range.

1 is a system schematic diagram used in an embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of a base station access device of FIG. 1.

3 is a detailed block diagram of the base station apparatus of FIG.

4 is a detailed circuit diagram of a wireless signal processor of FIG.

5 is a flowchart of an inter-cell bearer handover referred to in an embodiment of the present invention.

6A-6H are message structures of a handover request referred to in an embodiment of the present invention.

7A and 7B are flowcharts of a base station connection apparatus referred to in the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A detailed description of a preferred embodiment of the present invention will now be described with reference to the accompanying drawings. In the following, reference numerals are given to components of each drawing, even though the same components are shown in different drawings. Note that they have the same sign.

In describing the present invention, when it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Terms to be described later are defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or a chip designer, and the definitions should be made based on the contents throughout the present specification. First, the general characteristics and protocol structure of the DECT for implementing the on-premises wireless telephone system according to the present invention will be described. It should be noted that the content described herein is only a part of the contents disclosed in ETS 300 175-1 to 175-9.

I. General characteristics

Frequency band: 1880 ?? 1900MHz

Number of carriers: 10

Carrier occupancy area; 1.728 MHz-peak transmit power: 250 mW

Carriermultiplex: TDMA (24 slots per frame)

Frame length: 10 ms

Basic duplexing; TDD using the same RF carrier in two slots

Gross bit rate: 1152 kbit / s

Net channel rates: 32 kbit / s (B slot (traffic) in each slot), 6.4 kbit / s (A field (control / signaling) in each slot)

II. Protocol Architecture

Physical Layer (PHL): This function separates radio spectrum into physical channels in a fixed frequency and time dimension.

Medium Access Control Layer (MAC Layer): Creates, maintains and releases a bearer by selecting physical channels and accessing or releasing the selected physical channels, and performing control information. It performs the function of multiplexing and demultiplexing packet information of slot unit together with upper layer information and error control information. The functions of the media access control layer may be classified into cluster control functions and cell site control functions.

Data Link Control Layer (DLC Layer): Performs a function of making or disconnecting a connection in response to a request of a network layer.

Network Layer (NWK Layer): Performs the function of exchanging messages for call establishment, maintenance, and release.

The premises wireless telephone system according to the embodiment of the present invention for accommodating the DECT terminal subscriber having the above characteristics and protocol structure is a PABX or key phone system (hereinafter referred to as a "main system") 100 as shown in FIG. At least).

In FIG. 1, the main system 100 not only includes the same components of the existing PABX or keyphone system but also additionally, one master base station connection device 120 and a plurality of slave base station connection devices 130 and 140. ) Is implemented more.

The analog interface 150, the keyset interface 160, the digital phone (DGP) interface 170, the serial output interface 180 and the analog trunk interface 190 of the main system 100 can be checked in the existing PABX or keyphone system. The possible components are:

In addition, the CPU 110 not only controls the overall operation of the call service performed in the existing PABX or key phone system, but also provides an operation of providing a wireless call service to the DECT terminal according to an embodiment of the present invention. To control.

It should be noted that other components for the operation of the call service performed in the existing PABX or keyphone system, for example, switching circuits, ring detectors, ring generators, dual tone multi frequency (DTMF), etc. It is a fact that only the various interfaces and the CPU 110 are shown to show that the subscribers are connected, not shown inside the 100.

The analog interface 150, the keyset interface 160, and the digital phone interface 170 of the main system 100 perform functions of interfacing general telephones, key phones and digital phones, respectively, and the serial output (SO) interface 180. Each of the and the analog trunk interface 190 is connected to an Integrated Services Digital Network (ISDN) and a Public Switched Telephone Network (PSTN).

Referring to FIG. 1, the main system 100 according to an embodiment of the present invention includes one master base station access device 120 and a plurality of slaves for providing a wireless call service to a DECT terminal (portable device). Slave) The base station access devices 130 and 140 are mounted in their slots.

The master base station access device 120 and the slave base station access devices (130, 140) are configured in the same way as can be seen from the description of FIG.

However, by the CPU 110, one base station connecting device is set as a master base station connecting device, and the other base station connecting devices are set as slave base station connecting devices.

In this case, the number of base station access points may be appropriately designed according to a designer's intention. It should be noted that only two slave base station access points are illustrated in FIG. 1.

A plurality of base stations 200 and 300 are connected to the master base station access device 120 by wire, and a plurality of base stations 400 and 500 are connected to the slave base station access device 130 by wire.

A plurality of portable devices are wirelessly connected to each base station. A plurality of portable devices 202 ?? 208 are connected to the base station 200, and a plurality of portable devices 302 ?? 308 are connected to the base station 300. A plurality of portable devices 402 ˜ 408 are connected to the base station 400, and a plurality of portable devices 502 ˜ 508 are connected to the base station 500.

Each of the base stations performs cell site function of the MAC layer of the DECT protocol by communicating with portable devices that access themselves through a wireless communication channel.

Each slave base station access device mounted in a slot of the main system 100 communicates with a base station connected to itself and performs a cluster control function of a MAC layer among DECT protocols and a mobile device attempting to connect with itself. primitive) is transmitted to the master base station access device 120, and performs a cluster control function according to the primitives received from the master base station access device 120.

The master base station access device 120, which is also mounted in the slot of the main system 100, communicates with the base station connected thereto to perform cluster control functions of the MAC layer of the DECT protocol with the mobile device and process the protocols of the DLC layer and the NWK layer. do.

In addition, the master base station access device 120 processes the DLC layer and NWK layer protocols with the mobile device connected to the slave base station access device, and communicates with the CPU 110 to convert the primitives received therefrom into the DECT protocol. Proceed to or notify the CPU 110 the primitives according to the DECT protocol execution result to provide a wireless call service.

2 is a view showing in detail the configuration of the master base station access device 120 and the slave base station access device (130, 140) mounted in the main system 100 according to the present invention.

As described above, the master base station access device 120 and the slave base station access devices 130 and 140 are configured in the same manner.

Referring to FIG. 2, the base station access unit includes a main system connection unit 122 that is in charge of connection with an existing PABX or key system, and a base station connection unit that performs a function of exchanging signals with the base station for connection with the base station. 124, and a control unit 126 for controlling each operation of the main system connection unit 122 and the base station connection unit 124.

The main system connection unit 122 is responsible for various signal connection and control data transmission / reception for the voice signal with the existing PABX or key system for accommodating the subscriber of the DECT terminal, and the transmission and reception of the control data is a dual port RAM. ), Synchronous communication, asynchronous communication, and the like.

This control data is used to convert the primitives received from the main system to proceed with the DECT protocol, or to send the primitives to be notified to the main system as a result of performing the DECT protocol to provide the wireless call service. In addition, the slave base station access device is used to transmit and receive primitives according to the execution of the cluster control function of the MAC layer, and the master base station access device is used to transmit and receive primitives according to protocol processing of the DLC layer and the NWK layer. The base station access unit 124 is connected to the base station to transmit and receive voice data, control data for DECT protocol processing, base station synchronization signal, and the like. The voice data received from the base station is transferred to the main system through the base station connection unit 124 and the main system connection unit 122, and the voice data from the main system is transferred to the base station. The control data for processing the DECT protocol received from the base station is transmitted to the control unit 126, and the control data and the synchronization signal received from the control unit 126 are transmitted to the base station. The control unit 126 controls the base station access point as a whole. In this case, it has a memory storing a program and a database required for controlling the access point of the base station. The program for controlling the master base station access device 120 may include software for guaranteeing connection and reliable communication with a base station connected thereto (eg, Link Access Procedures Balanced (LAPB), Link Access Procedures on the LAPD). D-channel) or Asynchronous], MAC layer multi-bearer control software that controls the multiplexing and management of all data through MAC layer connection with portable devices, and NWK layer. DLC layer processing software that provides reliable datalinks, NWK layer processing software, which is the main signaling layer of the DECT protocol, software for ensuring reliable communication with the main system, and connection with slave base station access devices. Software to handle this is included. The program for controlling the slave base station access device includes software (e.g., LAPB, LAPD, or Asychonous method) to ensure reliable communication with the connected base station and all data through MAC access to the mobile device. MAC layer multi-bearer control software for controlling the multiplexing and processing of the data, and software for handling the connection with the master base station access device. The database stores information on the portable device received from the main system, information on the slave base station access device and the base station, DECT protocol processing, and various variables necessary to ensure reliable communication with the base station.

3 is a view showing in more detail the configuration of a base station according to an embodiment of the present invention. Referring to FIG. 3, the base station processes a voice signal from the base station connecting device 210 for exchanging signals by connecting to the base station connecting device, and transmits the voice signal to the DECT protocol processor 230. The voice signal processing unit 220 processes the voice signal from the DECT protocol processor 230 and transmits the voice signal to the base station connection device connection unit 210, and processes the part of the PH layer and the MAC layer of the DECT protocol to the wireless signal processor 260. A connected DECT protocol processor 230, a controller 250 for controlling the operation of each part, a wireless signal processor 260 for processing a radio signal to enable communication between the base station and the portable device, and a power source for the base station It is composed of a power supply 240 for supplying. The base station access point connection unit 210 is connected to the base station access point and transmits and receives voice data, control data for DECT protocol processing, base station synchronization signal, and the like. That is, the base station access point connection unit 210 transfers the voice data received from the base station access point to the voice processing unit 220 and delivers the voice data received from the voice processing unit 220 to the base station access point, and receives from the base station access point. The control data for the DECT protocol processing is transferred to the control unit 250, the control data received from the control unit 250 is transmitted to the base station access device, and the base station access signal from the base station access device receives the DECT protocol processor 230. To pass. In addition, the base station connection device connection unit 210 transfers the power from the base station connection device to the power supply unit 240. The voice processing unit 220 receives voice data from the base station access unit 210 to suppress and remove echo, converts a PCM signal into an adaptive differential pulse code modulation (ADPCM) signal, and then selects a DECT. Transfer to the protocol processor 230. In addition, the voice processor 220 converts the ADPCM signal received from the DECT protocol processor 230 into a PCM signal, suppresses and removes the echo, and transmits the echo signal to the base station access point 210. The DECT protocol processor 230 processes a part of the PH layer and the MAC layer of the DECT protocol, transfers the ADPCM voice data received from the voice processor 220 to the wireless signal processor 260 and receives it from the wireless signal processor 260. The voice data is transmitted to the voice processor 220. The controller 250 performs an operation of controlling the base station as a whole, and has therein a memory storing various programs and databases necessary for controlling the base station. In addition, the control unit 250 is connected to the maintenance / repair terminal to check the state of the base station when necessary. Programs include software (LAPB, LAPD, or Asynchronous) to ensure connection and reliable communication with the base station access device connected to it, software for setting, maintaining, and releasing a dummy bearer, and a traffic bearer ( software for setting, maintaining, and releasing a traffic bearer, software for controlling a broadcast message, software for controlling a wireless connection, and the like. The database stores identification values assigned to the base station and various variables required for each software process. The power supply unit 240 converts the power supplied from the base station connecting device connection unit 210 or the power supplied from the power adapter (DC / DC) and supplies them to each component of the base station.

4 is a view showing in detail the configuration of the radio signal processing unit 260 of the configuration of the base station according to the present invention.

The modulator 262 is implemented as a Gaussian filter, and modulates the data from the DECT protocol processor 230 and outputs the modulated data. The frequency up converter 264 doubles the frequency of the data modulated by the modulator 262 to convert the frequency up to a frequency actually used. The band pass filter 266 suppresses signals other than the 1.88 ?? 1.9 GHz frequency band used in the system. Accordingly, the signal used in the system is output without being attenuated, and the unnecessary band signal not used in the system is attenuated and output. The power amplifier 268 uses a high output amplifier as an amplifier used to increase the output of a signal to be transmitted to the antenna AT. The transmission / reception switching switch 270 selects the transmission and reception of the radio signal, and is controlled by the DECT protocol processor 230. The bandpass filter 272 filters out an unnecessary band of the signals received from the antenna AT, and passes only signals in the 1.88 ?? 1.9 GHz frequency band used in the system. The low noise amplifier 274 is a high sensitivity amplifier with low noise for amplifying a very weak level signal received from the antenna AT. The bandpass filter 276 passes only signals in the 1.88 1 1.9 GHz frequency band used in the system among the output signals of the low noise amplifier 274. The frequency down converter 270 lowers the frequency of the received signal using 110.592 MHz. The amplifier 280 amplifies the output of the downlink frequency converter 278. The demodulator 282 extracts data from the modulated radio signal, and the data extracted by the demodulator 282 is provided to the DECT protocol processor 230. The radio of the radio signal processor 260 is configured as described above. A description will be given of the connection processing operation divided into transmission and reception. In the case of transmission, the 1.152 Mbps signal sent from the DECT protocol processor 230 is modulated by a Gaussian filter, and the modulated signal is doubled and output by the uplink frequency converter 264. Since the unnecessary band signal of the output signal of the uplink frequency converter 264 is removed by the band pass filter 266, the power amplifier 268 inputs only a signal used in the system and then amplifies and outputs the power of the signal. The amplified signal is propagated to the air through the antenna AT via the transmission / reception switching switch 270. Since the antenna AT has a diversity structure as shown in FIG. 4, one of the two antennas is used and the other antennas can be switched according to the request of the terminal. In the case of reception, only the signals of the 1.88 ?? 1.9 GHz band are detected by the band pass filter 272 among the signals input to the antenna AT by sensing radio waves in the air. The signal passing through the bandpass filter 272 is low noise amplified by the low noise amplifier 274, and the low noise amplified signal is again filtered by the band pass filter 276 so that the signal of the unnecessary band is removed, i.e., in the system Only the signal of the frequency used is applied to the downlink frequency converter 278. The signal frequency in the 1.9 GHz band output from the bandpass filter 276 is down to a frequency suitable for extracting data by the downlink frequency converter 278. The down signal is amplified by the amplifier 280 and then demodulated. 282 is input and demodulated. The demodulated data is provided to the DECT protocol processor 230 to be processed.

5 is a flow chart of inter-cell bearer handover processing according to an embodiment of the present invention, and FIGS. 6A-6H are examples of each message according to the flow of each sequence of FIG. 5.

7A and 7B are flowcharts of a base station access apparatus according to an embodiment of the present invention.

A first step of checking whether or not the MBC-IE-TBC-HANDOVER-REQUEST message has been received to the area of the second base station apparatus while the terminal is talking to the first base station apparatus;

A second step of checking whether an MBC-IE-TBC-HANDOVER-REQUEST message has the same PMID among MBC TASK management tables currently in use when the first step receives the message;

A third step of releasing the bearer by transmitting an MFP-MBC-BEARER-RELEASE message when none of the MBC TASK management tables have the same PMID in the second step;

Will there be the same PMID in the MBC TASK management table in the second step? Sending a MBC-IE-TBC-HANDOVER-REQ message and checking whether it matches the base station apparatus of the base station apparatus and the PRINCIPAL bearer stored in the MBC management table;

In the third step, if it does not match, perform Intra-Cell bearer handover processing, and if there is a match, issue the MFP-LLME-HANDOVER-IND to the LLME task of the master base station access device to inquire whether handover is possible. Wow,

A fifth step of checking whether the handover is possible if the MBC-IE-LLME-HANDOVER-RES message is received from the master base station access device in response to the handover in the fourth step;

If the handover is not possible in the fifth step, the MFP-MBC-TBC-BEARER-RELEASE message is transmitted to the second base station apparatus to release the bearer. If the handover is possible, the MFP-MBC-BEARER is transmitted to the second base station. A sixth step of transmitting a GRANT message and an MFP-ME-CONNECTION-BCH message to make a B-channel connection with the handover bearer;

When the connection is completed in step 6, if there is an MBC-IE-TBC-BEARER-ESTABLISHED message indicating that the handover bearer is set up from the second base station, the MFP is transmitted to the first base station to release the PRINCE bearer. In the seventh step, it transmits the message -MBC-TBC -BEARER-RELEASE and sends the HANDER-REQ message to the exchange to switch the B channel.

Therefore, a specific embodiment of the present invention will be described in detail with reference to FIGS. 5 to 7A and 7B.

When the terminal is in communication with the first base station apparatus in step 7a and moves to the area of the second base station apparatus and determines that the connection state with the first base station apparatus is poor, the bearer handover is performed to the second base station apparatus. A bearer handover request message is sent to perform the operation. That is, the second base station apparatus allocates a traffic bearer and transmits a MBC_IE_HANDOVER_REQUEST message as shown in FIG. 6A to a multi bearer control (MBC) task of the base station access apparatus. In step 7b, it is checked whether the message is received.

If the message is received, the MBC_IE_HANDOVER_REQUEST message includes the ID of the base station apparatus and the MAC layer identifier (PMID) of the terminal. In step 7c, it is checked whether the MBC task management table currently in use has the same PMID.

When the same PMID does not exist in step (7c), the bearer is released by transmitting the MFP-MBC-BEARER-RELEASE message of FIG. 6G in step (7i). In the MBC task, the MBC_IE_HANDOVER_REQUEST message is received in the state of already maintaining a traffic bearer with the first base station apparatus. It checks whether the same value exists in the management table of the PMID and the MBC task in the message. The same value exists when normal handover is possible.

If the same PMID exists (7d), this time is compared with the ID of the base station apparatus stored in the management table of the MBC task (in this embodiment, the base station apparatus 0 is stored) and the base station apparatus ID in the MBC_IE_HANDOVER_REQUEST message. If the values are the same, it is an intra-cell bearer handover occurring in the same base station. If the values are different, the values are bearer handovers occurring between different base stations. When the MBC_IE_HANDOVER_REQUEST message is received in step (7e), it is a lower layer management entity (LLME) task of the master base station access device (MFP_LLME_HANDOVER_IND) to determine whether handover is possible to the second base station device. Generates a message (this includes the ID of the base station access point and the ID of the base station access point), inquires whether handover is possible, and (7f) processes the MBC-IE-LLME-HANDOVER-RES from the master base station access point. Check whether or not If there is a message reception in step (7f), it is checked whether handover is possible in step (7g). That is, in this embodiment, since it is a bearer handover occurring between different base stations, the ID of the base station apparatus in which the primitive bearer is already stored in the management table of the MBC task and the MBC_IE_HANDOVER_REQUEST of FIG. 6A. The ID of the base station apparatus that sent the message is different.

The LLME task having received the MFP_LLME_HAND_IND of FIG. 6C finds an assignable B channel using the ID of the base station access apparatus and the ID of the base station apparatus, and transfers it to MBC_IE_LLME_HANDOVER_RES of FIG. 6C as an MBC task. The MBC task that has received the MBC_IE_LLME_HANDOVER_RES receives the MFP_MBC_BEARER_GRANT message of FIG. 6D as a traffic bearer control (TBC) task of the second base station device to generate a new traffic bearer when handover is possible in step 7g. The base station apparatus which receives the message transmits a "bearer confirm" message to the terminal.

The MBC task also transmits the MFP_ME_CONNECT_BCH (assigned B channel) of FIG. 6E to the base station apparatus to instruct the handover bearer, the bearer connection, and the B channel to be connected.

If the handover is not possible in step 7g, the bearer is released by transmitting the MFP-MBC-TBC-BEARER-RELEASE to the second base station apparatus.

The TBC task of the base station apparatus transmits the MBC_IE_TBC_BEARER_ESTABLISHED message of FIG. 6F to the MBC task of the base station access apparatus when the traffic bearer with the terminal is completely set, and checks whether or not it is received in step 7l.

In this case, two traffic bearers (principal bearer and handover bearer) exist.

Now, in (7m), the MBC task sends the MFP_MBC_BEARER_RELEASE message to release the principal bearer, and then the LLME task requests the switching of the B channel allocated to the terminal to the key system or PABX main processor. A HANDOVER_REQ message is transmitted to allow intercell bearer handover by B channel switching.

The TBC task of the base station apparatus receiving the MFP_MBC_BEARER_RELEASE message completes the inter-cell bearer handover procedure by sending a "release" message to release the bearer established with the terminal.

As described above, in the case of a deck type wireless telephone system, which is intersected by inter-cell bearer handovers generated between base stations in a TDMA / TDD-type wireless wireless telephone system, the base station is accommodated in the wireless wireless telephone system. The bearer handover process occurring between the two devices eliminates the disconnection of the call by using another scheme such as switching of a voice line, so that the user's mobility can be extended and compensated.

Claims (1)

A method of providing a wireless call service by accepting subscribers of a DECT terminal in a private exchange or a key phone system, A first step of checking whether the DECT terminal receives the MBC-IE-TBC-HANDOVER-REQUEST message to the area of the second base station apparatus while the DECT terminal is talking to the first base station apparatus; A second step of checking whether an MBC-IE-TBC-HANDOVER -REQUEST message has the same PMID among MBC task management tables currently in use when the message of the first step is received; A third step of releasing the bearer by transmitting an MFP-MBC-BEARER-RELEASE message when none of the MBC task management tables have the same PMID in the second step; Is there same PMID among MBC task management table in the second step? Sending a MBC-IE-TBC-HANDOVER-REQ message and checking whether it matches the base station apparatus of the base station apparatus and the PRINCIPAL bearer stored in the MBC management table; In the third step, if it does not match, perform Intra-Cell bearer handover processing, and if there is a match, issue the MFP-LLME-HANDOVER-IND to the LLME task of the master base station access device to inquire whether handover is possible. Wow, A fifth step of checking whether the handover is possible if the MBC-IE-LLME-HANDOVER-RES message is received from the master base station access device in response to the handover in the fourth step; If the handover is not possible in step 5, the MFP-MBC-TBC-BEARER-RELEASE message is transmitted to the second base station apparatus to release the bearer. If the handover is possible, the MFP-MBC-BEARER is transmitted to the second base station. A sixth step of transmitting a GRANT message and an MFP-ME-CONNECTION-BCH message to make a B-channel connection with the handover bearer; When the connection is completed in step 6, if the MBC-IE-TBC-BEARER-ESTABLISHED message indicating that the handover bearer is established from the second base station to the first base station is released to the first base station to release the PRINCE bearer. The bearer handover between base stations in a Dect-type wireless switchboard is characterized by the seventh step of sending a MFP-MBC-TBC-BEARER-RELEASE message and sending a HANDER-REQ message to the exchange to switch between B-channels. Treatment method.

Images