KR20040012300A - Method for idle handoff of a mobile communication system - Google Patents

Abstract

PURPOSE: An idle handoff method in a mobile system is provided to shorten the time of call processing by storing the overhead message of the previous cell, when an idle handoff is generated, and utilizing the stored overhead message if an idle handoff from the present cell to the previous cell is generated. CONSTITUTION: In case that an MS(Mobile Station) moves a cell(A) to another cell(B), the MS monitors the paging channels of the first and second BTSs(Base station Transceiver Subsystem) in a sleep mode(S101-S103). The MS compares the pilot signal strength of the second BTS with the pilot signal strength of the first BTS(S105). If the pilot signal strength of the second BTS meets an idle handoff condition as it is larger than the pilot signal strength of the first BTS as much as an appointed level, the MS is synchronized with the second BTS(S109). The MS, synchronized with the second BTS, receives an overhead message sent from the second BTS's paging channel and updates the present overhead message. If the overhead message is normally received, the MS returns to an idle mode(S113-S117).

Description

Idle handoff method in mobile communication system {METHOD FOR IDLE HANDOFF OF A MOBILE COMMUNICATION SYSTEM}

The present invention relates to an idle handoff method of a mobile communication system, and more particularly, to idle handoff from a current cell to a previous cell after storing an overhead message of a previous cell when an idle handoff occurs. Is generated, the idle handoff method of the mobile communication system to utilize the stored overhead message.

A typical mobile communication system is a mobile station (MS), a base station (20, 25) (base station transceiver subsystem (BTS), a base station controller 30 (Base), as shown in the configuration diagram of FIG. Station Controller (BSC), Base Station Manager 35 (Base Station Manager; BSM), Switcher 40 (Mobile Switching Center; MSC), Visitor Location Register (VLR), Authentication Center (50) (Authentication Center; AC), and Home Location Register (HLR).

The mobile terminal 10 is a terminal capable of communicating in a service area composed of a plurality of cells (A, B, etc.) while being carried by a person and freely moving. The mobile terminal 10 is in a range of arbitrary base stations 20 and 25, Information of the 10 is transmitted to the exchange 40 via the base station 20, 25 and the base station controller 30 controlling the same, and the information transmitted from the exchange 40 is controlled by the base station 20, 25 and the base station. Is transmitted to the mobile terminal 10 via the device 30.

The base station 20, 25 connects the mobile terminal 10 to the base station controller 30, a digital channel unit (DCU), a timing / frequency control unit (TCU), a wireless device. A radio frequency unit (RFU), a global positioning system (GPS), and the like.

In addition, the base stations 20 and 25 communicate wirelessly with the mobile terminal 10 and perform a wired / wireless conversion function for communicating with the base station controller 30 by wire.

The base station controller 30 connects the base stations 20 and 25 to the exchange 40 to coordinate the connection between the base stations 20 and 25, supports a plurality of base stations 20 and 25, and supports the base stations 20 and 25. ) And a signal processing function for communication between the exchange 40.

The exchange 40 connects a call when the subscriber of the mobile phone makes or receives a call. The switch 40 connects to the base station controller 30 to perform a call setup and release function of the mobile terminal 10. It performs various functions related to and performs interworking function with other networks.

The visitor location register 45 is a database that stores information of visited subscribers in the area serviced by the exchange 40, and the home location register 55 stores information of the mobile terminal 10 and the subscriber whose location is registered in the area in charge of the visitor. Take from and store temporarily. Visitor location register 45 is typically mounted on exchange 40.

The home location register 55 is a database that stores permanent information of the mobile terminal 10 and subscribers, location information, and additional service information. The authentication center 50 interacts with the exchange 40 to process a call. And perform various functions related to additional services and control services.

Usually, a plurality of home location registers 55 may exist in one service network, and one or more exchanges 40 may be connected to one home location register 55, and several exchanges 40 may be connected to one switch 40. One base station controller 30 may be connected, and one base station controller 30 may be connected to several base stations 20 and 25.

In the mobile communication system configured as described above, the mobile terminal 10 has a no service state such as a no pilot state, a pilot channel acquisition state, and a synchronization channel acquisition state. In order to normally transition to an idle state, an overhead message, which is basic information coming down from a cell (base station or sector) to a paging channel, must be normally received.

After the corresponding overhead message is normally received and transitioned to the idle state, the mobile terminal 10 can normally transmit and monitor the paging channel periodically to receive an incoming call.

In addition, after the handoff occurs between the base stations 20 and 25 or the sector, the mobile terminal 10 must receive all the overhead messages of the active base station or sector after the handoff. .

The overhead messages coming down from the cells of current CDMA2000 1X and IS-95 A / B mobile communication systems include system parameter messages, access parameter messages, and CDMA channel list messages. Message, Neighbor List Message, Extended System Parameter Message, etc.The parameters of these overhead messages can be operated differently for each base station for optimization purposes, After the operation is rarely changed by the system operator, and the parameter values are not significantly different for each base station and are used as almost equivalent values.

In addition, in the CDMA2000 1X and IS-95A / B standards, the corresponding overhead message is transmitted in the cell more than once within 1.28sec, and the message sequence in the overhead message when the operator changes the overhead message. ) Is increased by +1. Accordingly, the mobile terminal 10 may check the message sequence coming down to the paging channel and check whether the previously stored overhead message has been changed.

2 is a flowchart illustrating an idle handoff process from base station # 1 to base station # 2 according to the prior art, and FIG. 3 is a flowchart illustrating an idle handoff process from base station # 2 to base station # 1 according to the prior art.

Referring to FIGS. 2 and 3, the handoff processing procedure when the mobile terminal 10 moves from cell A to cell B and then to cell A will be described in detail.

First, in the case of the movement from cell A to cell B, the mobile terminal 10 establishes a paging channel of the base station # 1 20 and the base station # 2 25 so as to periodically check paging in the sleep mode. It monitors (S11-S13).

The mobile terminal 10 measures the signal strength of the pilot when monitoring the paging channel, and the pilot signal strength of the base station # 2 (25) is further increased by a certain level (currently 3 dB) when compared to the pilot signal strength of the base station # 1 (20). If large, i.e., if the idle handoff condition is satisfied, tuning is performed to the base station # 2 25. If the idle handoff condition is not satisfied, tuning to the base station # 1 20 is maintained (S15 to S21).

The mobile terminal 10 tuned to the base station # 2 25 receives the overhead message coming down from the paging channel of the base station # 2 25 to update the current overhead message, and the overload of the base station # 2 25 If the head message is normally received, the transition to the idle state (S23 to S27).

At this time, the overhead message of the base station # 2 (25) is stored in the overhead message memory. The overhead message of the base station # 1 (20) stored in the overhead message memory is an overhead message of the base station # 2 (25). It is overwritten (S29).

After the mobile terminal 10 transitions to the sleep state, the mobile terminal 10 periodically monitors the paging channel of the base station # 2 25 according to the slot cycle index value. At this time, the message sequence is checked to determine the validity of the existing overhead message (S31 to S35).

In addition, the mobile terminal 10 attempts an outgoing process when a user requests an outgoing request, and when an incoming request occurs, the mobile terminal 10 connects the mobile terminal 10 to a corresponding call path and processes the incoming call (S37).

Next, in case of a return movement from cell B to cell A, the mobile terminal 10 checks paging of the base station # 1 20 and the base station # 2 25 periodically to check paging in the sleep mode. The channel is monitored (S52 to S54).

The mobile terminal 10 measures the signal strength of the pilot when monitoring the paging channel, and the pilot signal strength of the base station # 1 (20) is a certain level (currently 3 dB) when compared to the pilot signal strength of the base station # 2 (25). If large, i.e., if the idle handoff condition is satisfied, tuning is performed to the base station # 1 20. If the idle handoff condition is not satisfied, tuning to the base station # 2 25 is maintained (S56 to S62).

The mobile terminal 10 tuned to the base station # 1 (20) receives the overhead message coming down from the paging channel of the base station # 1 (20) to update the current overhead message, the base station # 1 (20) over If the head message is normally received, the transition to the idle state (S64 to S68).

At this time, the overhead message of the base station # 1 (20) is stored in the overhead message memory. The overhead message of the base station # 2 (25) stored in the overhead message memory is an overhead message of the base station # 1 (20). It is overwritten (S70).

After the mobile terminal 10 transitions to the sleep state, the mobile terminal 10 periodically monitors the paging channel of the base station # 1 20 according to the slot cycle index value. At this time, the validity of the existing overhead message is determined by checking the message sequence (S72 to S76).

In addition, the mobile terminal 10 attempts an outgoing process when a user requests an outgoing request, and when an incoming request occurs, the mobile terminal 10 connects the mobile terminal 10 to a corresponding call path and processes the incoming call (S78).

On the other hand, in the traffic state, the soft handoff (including soft handoff) ratio between cells is 70% or more, and the boundary areas between the cells are overlaid. Therefore, considering that the radio wave intensity varies in the idle state in the mobile terminal 10, idle handoff occurs frequently in many regions.

In addition, the mobile terminal 10 in the cell boundary region having similar signal strength frequently receives an idle handoff, and receives a corresponding overhead message as described above in order for the subscriber to attempt a call when the idle handoff occurs. shall.

If continuous idle handoff occurs in the mobile terminal 10 in such a boundary area, call processing is not performed properly. In order to prevent this, the mobile terminal 10 has a margin between the cells as shown in steps S17 and S58. Idle handoff is performed only if the signal strength differs by more than 3 dB.

However, even when the margin is set, the idle area frequently occurs in the border region, and the frequent idle handoff causes a call processing delay and the battery of the mobile terminal 10 is severely consumed to process the overhead message change. .

The present invention has been proposed to solve such a conventional problem. When the idle handoff occurs, when the idle handoff occurs from the current cell to the previous cell after the overhead message of the previous cell is stored, the stored overhead message is utilized. The purpose of the present invention is to shorten the time that a mobile terminal can normally attempt to process a call and to minimize the operating time for receiving a corresponding overhead message, thereby minimizing battery consumption of the mobile terminal.

In the idle handoff method of the mobile communication system according to the present invention for realizing the above object, when the idle handoff occurs to the base station # 2 in synchronization with the base station # 1, the base station # 2 received by tuning to the base station # 2 Updating the current overhead message with an overhead message of < RTI ID = 0.0 > and < / RTI > storing an overhead message of base station # 1; Checking a message sequence of an incoming overhead message and comparing the checked message sequence with a message sequence of an overhead message of the previously stored base station # 1; if the compared message sequence is the same, an overload of the previously stored base station # 1 Updating the head message with the current overhead message, and storing the overhead message of base station # 2.

1 is a block diagram of a general mobile communication system;

2 is a flowchart illustrating an idle handoff process from base station # 1 to base station # 2 according to the prior art;

3 is a flowchart illustrating an idle handoff process from base station # 2 to base station # 1 according to the prior art;

4 is a flowchart illustrating an idle handoff process from base station # 1 to base station # 2 according to the present invention;

5A and 5B are flowcharts illustrating an idle handoff process from base station # 2 to base station # 1 according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: mobile terminal 20, 25: base station

30: base station control device 35: base station management device

40: Exchanger 45: Visitor Location Register

50: Certification Center 55: Home Location Register

There may be a plurality of embodiments of the present invention. Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention.

Referring to the gist of the present invention, a mobile terminal includes a current overhead message memory for storing an overhead message of an active cell and a past overhead message memory for storing an overhead message of an old active cell.

When an idle handoff occurs from cell A to cell B and the mobile terminal normally receives the overhead message of cell B and enters the idle state, the overhead message of cell B is replaced with the current active overhead message without erasing the overhead message of cell A. It stores the overhead message of cell A as an overhead message of the old active cell.

When the idle handoff occurs again from cell B to cell A, the overhead message of cell A stored in the memory is compared with the sequence of messages of the paging channel coming down from cell A. Determining and transitioning to an idle state, storing the overhead of the cell B as an old active overhead message, and storing the overhead message of the cell A as an overhead message of the current active cell.

The hardware configuration of the mobile communication system for performing the idle handoff method according to the present invention is as shown in Figure 1, the mobile terminal 10 (Mobile Station (MS)), the base station 20, 25 (Base Station Transceiver) Subsystem; BTS, Base Station Controller 30 (Base Station Controller; BSC), Base Station Manager 35 (Base Station Manager; BSM), Switcher 40 (Mobile Switching Center; MSC), Visitor Location Register 45 (Visitor Location Register (VLR)), an authentication center 50 (Authentication Center; AC), and a home location register 55 (Home Location Register; HLR).

The mobile terminal 10 is a terminal capable of communicating in a service area composed of a plurality of cells (A, B, etc.) while being carried by a person and freely moving. The mobile terminal 10 is in a range of arbitrary base stations 20 and 25, Information of the 10 is transmitted to the exchange 40 via the base station 20, 25 and the base station controller 30 controlling the same, and the information transmitted from the exchange 40 is controlled by the base station 20, 25 and the base station. Is transmitted to the mobile terminal 10 via the device 30.

The mobile terminal 10 includes a current overhead message memory for storing the overhead message of the active cell and a past overhead message memory for storing the overhead message of the old active cell, and the overhead message of the previous cell when the idle handoff occurs. If an idle handoff occurs from the current cell to the previous cell after storing the in the past overhead message memory, the idle state is shifted to the idle state by using the stored overhead message.

The functional description of the other components is similar to that described through the prior art, and detailed description thereof will be omitted since it can be sufficiently inferred from the following description of the idle handoff process according to the present invention.

4 is a flowchart illustrating an idle handoff process from base station # 1 to base station # 2 according to the present invention, and FIGS. 5A and 5B illustrate an idle handoff process from base station # 2 to base station # 1 according to the present invention. It is a flow chart.

4 and 5a and 5b will be described in detail the handoff process according to the present invention when the mobile terminal 10 moves from cell A to cell B and then to cell A again.

First, referring to FIG. 4, in the case of a move from cell A to cell B, the mobile terminal 10 checks the paging periodically in the sleep mode, and the base station # 1 20 and the base station # 2 (25). Monitor the paging channel (S101 to S103).

The mobile terminal 10 measures the signal strength of the pilot when monitoring the paging channel. When the pilot signal strength of the base station # 2 25 is compared with the pilot signal strength of the base station # 1 20, the mobile terminal 10 measures a certain level (eg, 3 dB). If larger, that is, if the idle handoff condition is satisfied, tuning is performed to the base station # 2 25, and if the idle handoff condition is not satisfied, tuning to the base station # 1 20 is maintained (S105 to S111).

The mobile terminal 10 tuned to the base station # 2 25 receives the overhead message coming down from the paging channel of the base station # 2 25 to update the current overhead message, and the overload of the base station # 2 25 When the head message is normally received, the state transitions to the idle state (S113 to S117).

At this time, the overhead message of the base station # 2 (25) is stored in the current overhead message memory, and the overhead message of the base station # 1 (20) previously stored in the current overhead message memory is stored in the past overhead message memory. It stores (S119-S121).

After the mobile terminal 10 transitions to the sleep state, the mobile terminal 10 periodically monitors the paging channel of the base station # 2 25 according to the slot cycle index value. At this time, the validity of the existing overhead message is determined by checking the message sequence (S123 to S127).

In addition, the mobile terminal 10 attempts an outgoing process when a user requests an outgoing request, and when an incoming request occurs, the mobile terminal 10 connects the mobile terminal 10 to a corresponding call path and processes the incoming call (S129).

Next, referring to FIGS. 5A and 5B, in the case of a return movement from cell B to cell A, the mobile station 10 checks with the base station # 1 20 to periodically check paging in the sleep mode. The paging channel of the base station # 2 25 is monitored (S152 to S154).

The mobile terminal 10 measures the signal strength of the pilot when monitoring the paging channel. When the pilot signal strength of the base station # 1 20 is compared with the pilot signal strength of the base station # 2 25, the mobile terminal 10 measures a certain level (for example, 3 dB). If larger, i.e., if the idle handoff condition is satisfied, tuning is performed to the base station # 1 20, and if the idle handoff condition is not satisfied, tuning to the base station # 2 25 is maintained (S156 to S162).

The mobile terminal 10 tuned to the base station # 1 (20) checks the message sequence of the overhead message coming down from the paging channel of the base station # 1 (20), the confirmed message sequence and the past overhead message memory in step S121 It compares with the message sequence of the overhead message of the base station # 1 20 stored in (S164-S166).

If the message sequence is the same in step S166, the mobile terminal 10 does not receive the overhead message descending from the base station # 1 20 to the paging channel, but instead of the base station # 1 20 previously stored in the overhead message memory. The overhead message is updated with the current overhead message to transition to the idle state (S168 to S170). At this time, the overhead message stored in the past overhead message memory is stored in the current overhead message memory (S172).

If the message sequence is not the same in step S166, the mobile terminal 10 receives the overhead message coming down the paging channel from the base station # 1 (20), updates the current overhead message and transitions to the idle state, and the base station # 1 The overhead message received from the paging channel of 20 is stored in the current overhead message memory. At this time, the overhead message of the base station # 1 20 currently stored in the overhead message memory is overwritten by an overhead message having a new message sequence (S174 to S180).

Next, after performing step S172 or S180, the mobile terminal 10 stores the overhead message of the base station # 2 25, which has been stored in the current overhead message memory, in the past overhead message memory, and subsequently performs another idle operation. It can be utilized when a handoff occurs (S182).

After the mobile terminal 10 transitions to the sleep state, the mobile terminal 10 periodically monitors the paging channel of the base station # 1 20 according to the slot cycle index value. At this time, the message sequence is checked to determine the validity of the existing overhead message (S184 to S188).

In addition, the mobile terminal 10 attempts an outgoing process when a user requests an outgoing request, and when an incoming request occurs, the mobile terminal 10 connects the mobile terminal 10 to a corresponding call path and processes the incoming call (S190).

In the above description, but limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, in the boundary area of two cells in a fixed point or moving, the mobile terminal stores an overhead message stored in the conventional memory in order to transition to normal idle state after repeated idle handoff. By utilizing the overhead message, the time for the mobile terminal to normally attempt to process a call is much faster, and the operation of the mobile terminal to receive the overhead message is minimized, thereby minimizing battery consumption.

In particular, a more stable effect is expected in a mobile communication system operating in CDMA2000 1X and 95A / B and 1xEV-DO hybrid mode. Currently, 1X has higher priority than 1xEV-DO, so if a slot cycle index value of 1X is reached during 1xEV-DO call processing, it stops 1xEV-DO call processing and monitors 1X paging to check for paging and when there is no 1X paging. Come back to 1xEV-DO and try to handle the call continuously. However, when monitoring IX paging, if an idle handoff occurs between cells, an overhead message should be received, so the 1xEV-DO call processing may fail. Therefore, the mobile terminal in the cell boundary area can greatly affect the 1xEV-DO call processing. However, according to the handoff method of the present invention, it is possible to operate more stably, and there is an effect that the call processing can be performed more quickly even when the access handoff of CDMA2000 1X or 95B is performed.

Claims (4)

A handoff processing method between a cell managed by a base station # 1 and a cell controlled by a base station # 2 of a mobile communication system, When the idle handoff occurs to the base station # 2 in synchronization with the base station # 1, the current overhead message is updated with the received overhead message of the base station # 2 by tuning to the base station # 2, and the overhead message of the base station # 1 The first step of storing, When the idle handoff occurs to the base station # 1, it tunes to the base station # 1 to check the message sequence of the overhead message coming down from the paging channel of the base station # 1, and the confirmed message sequence and the previously stored overhead message of the base station # 1. A second step of comparing the message sequence of If the compared message sequence is the same, the idle handoff of the mobile communication system includes updating the previously stored overhead message of the base station # 1 with the current overhead message and storing the overhead message of the base station # 2. Way. The method of claim 1, wherein the first step, An eleventh step of measuring the signal strength of the pilot by monitoring the paging channels of the base stations # 1 and the base station # 2 to periodically check the paging in the sleep state; A twelfth step of tuning to the base station # 2 if the pilot signal strength of the base station # 2 is larger than the pilot signal strength of the base station # 1 by a certain level; A thirteenth step of receiving an overhead message coming down from the paging channel of the base station # 2 and updating the current overhead message, and transitioning to an idle state when the overhead message of the base station # 2 is normally received; An overhead message of the base station # 2 is stored in the current overhead message memory, and an overhead message of the base station # 1 previously stored in the current overhead message memory is stored in the past overhead message memory; An idle hand of the mobile communication system comprising the fifteenth step of determining the validity of the existing overhead message based on the message sequence by periodically monitoring the paging channel of the base station # 2 according to the slot cycle index value after the transition to the sleep state Off way. The method of claim 1, wherein the second step, A twenty-first step of monitoring the signal strength of the pilot by monitoring the paging channels of the base stations # 1 and the base station # 2 to periodically check paging in the sleep state; A twenty-second step of tuning to the base station # 1 if the pilot signal strength of the base station # 1 is larger than the pilot signal strength of the base station # 2; Idle of the mobile communication system including the step 23 of checking the message sequence of the overhead message coming down from the paging channel of the base station # 1, and comparing the message sequence of the confirmed message sequence and the overhead message of the base station # 1 Handoff method. The method of claim 1, wherein the third step, A thirty-first step of updating the overhead message of the previously stored base station # 1 with the current overhead message and transitioning to an idle state if the compared message sequences are the same; A thirty-second overhead message of the base station # 1 stored in the current overhead message memory; and an overhead message of the base station # 2 previously stored in the current overhead message memory; Steps, An idle hand of the mobile communication system comprising the step 33 of determining the validity of the existing overhead message based on the message sequence by periodically monitoring the paging channel of the base station # 1 after the transition to the sleep state according to the slot cycle index value Off way.