KR100356496B1 - Method for handling of soft hand-off in CDMA mobile communication system - Google Patents

Abstract

In the present invention, a code division multiple access mobile communication system for minimizing inter-sectoral handoff failure and call drop (call drop) by matching information of an active pilot between a higher processor and a lower processor during soft handoff is performed. The present invention relates to a method for processing soft handoff in a mobile communication system comprising a base station with CE and BCP and a control station with TSB and CCP. Determining whether one drop or two drops are received in one active area (Alpha) (Beta) (Gamma) receiving the soft handoff instruction message from the coder and the selector bank, and if the result of the determination in the step is one drop or two drops, Determining whether the active pilot is a drop pilot; and the determination result of the step is that the active pilot is not a drop pilot. And performing a handoff completion report to the TSB by completing one drop or two drops, and transmitting a Not Acknowledge (NAK) message to the TSB when the active pilot is a drop pilot.

Description

Method for handling of soft hand-off in CDMA mobile communication system

The present invention relates to a soft handoff processing method in a code division multiple access mobile communication system, and more particularly, to match the information of an active pilot between an upper processor and a lower processor during a soft handoff operation. The present invention relates to a soft handoff processing method in a code division multiple access mobile communication system to minimize handoff failure and call drop (call drop).

In general, each base station of a CDMA mobile communication system transmits a pilot carrier. The mobile station uses these pilot carriers to perform initial system synchronization and track and find the correct time, frequency, and phase signals.

The mobile station always tracks the pilot signal and requests handoff to the base station when the pilot signal falls below the threshold.

Here, the handoff mobile station refers to a procedure for continuing a call between the base station and the mobile station when the mobile station enters the service area of the neighboring base station out of the service area of the base station.

On the other hand, all well-known handoffs are performed by matching active pilot information between the Transcoder and Selector Bank (TSB) of the control station which is the main processor and the terminal MS. Therefore, when the start and end of the handoff is sent to the TSB by sending a Pilot Strength Measurement Message (PSMM) requesting a handoff from the terminal, the TSB sends a HDM (Handoff_Direction_Message: Handoff) to the terminal when a handoff condition is reached. In this case, the terminal completes the handoff and sends the HCM (Handoff_Completion_Message) to the TSB to terminate the handoff.

1 is a flowchart illustrating a soft_ADD processing method among soft handoff processing methods in a conventional CDMA mobile communication system.

As shown in FIG. 1, reference numeral 10 denotes a mobile station (MS), reference numeral 20 denotes a base station (BTS), reference numeral 21 denotes a channel element (CE) in the base station 20, and the like. : Denotes a channel element, reference numeral 22 denotes a base station control processor (BCP: BTS Control Processor) in the base station 20, reference numeral 30 denotes a control station (BSC) controlling the base station 20, Reference numeral 31 denotes a transcoder and selector bank (TSB) in the control station 30, and reference numeral 32 denotes a central control processor (CCP) provided in the control station 30. Reference numeral 40 denotes a mobile switching center (MSC).

Referring to the conventional SOFTER_ADD processing procedure with reference to the general mobile communication system configured as described above are as follows.

First, the mobile station 10 transmits a pilot strength measurement message (PSMM) to the TSB 31 in the control station 30, and the received TSB 31 determines whether or not the soft handoff is performed. If it is determined, a message (tc_stfr_ho_ctl_msg) indicating SOFTER_ADD is transmitted to the channel element 21 in the base station 20. The received channel element 21 transmits a response message (vs_ack_ctl_msg) to the TSB 31. Thereafter, the channel element 21 transmits a message (cc_stfr_ho_msg) requesting resource allocation required for SOFTER-ADD to the base station control processor (BCP) 22, and the received BCP 22 sends the corresponding resource to CE ( 21) (tc_mob_assign). Then, the CE 21 transmits a resource allocation message (vs_sftr_ho_rsp_ctl_msg) indicating what resource is allocated to the TSB 31, and the TSB 31 receives the response message (tc_ack_ctl_msg) to the CE 21. do. Then, the TSB 31 transmits a handoff direction message to the mobile station 10, and when the received mobile station 10 performs the handoff and the handoff is completed, the handoff completion message ( Handoff Completion Message) is transmitted to the TSB 31. The TSB 31 receives the handoff processing result message (Msg_tsb_handoff_Completion_Sc) to the central control processor 32, and the CCP 32 receives the response message (Msg_Ho_Compl_Ack_Cs) to the TSB 31. In addition, the mobile communication switch 40 transmits a message (Msg_Hoff_Perf_Cx) reporting the completion of the handoff.

2 is a flowchart illustrating a soft_DROP processing method among soft handoff processing methods in a conventional CDMA mobile communication system.

As shown in FIG. 2, reference numeral 10 denotes a mobile station (MS), reference numeral 20 denotes a base station (BTS), reference numeral 21 denotes a channel element (CE) in the base station 20. Reference numeral 22 denotes a base station control processor (BCP: BTS Control Processor) in the base station 20, reference numeral 30 denotes a control station (BSC) for controlling the base station 20, and reference numeral 31 Denotes a transcoder and selector bank (TSB) in the control station 30, reference numeral 32 denotes a central control processor (CCP) provided in the control station 30, Reference numeral 40 denotes a mobile switching center (MSC).

Referring to the conventional SOFTER_DROP processing procedure with reference to the general mobile communication system configured as described above are as follows.

First, the mobile station 10 transmits a pilot strength measurement message (PSMM) to the TSB 31 in the control station 30, and the TSB 31 receives the handoff direction message to the mobile station 10 (Handoff Direction Message). When the handoff is completed after the handoff is performed, the mobile station 10 transmits a handoff completion message to the TSB 31. The TSB 31 receives the message (tc_stfr_ho_complete_ctl_msg) indicating completion of the SOFTER_DROP handoff to the CE 21, and the CE 21 receives the response message (vs_ack_ctl_msg) to the TSB 31. To pass. In addition, the CE 21 releases the handoff allocation resource and transmits a completion message (cc_ho_cmpl_msg) to the BCP 22. Next, the TSB 31 transmits a handoff completion message (Msg_tsb_handoff_Completion_Sc) to the central control processor 32, and the CCP 32, which has received it, transmits a response message (Msg_Ho_Compl_Ack_Cs) to the TSB 31, The mobile communication exchange 40 transmits a message (Msg_Hoff_Perf_Cx) reporting the completion of the handoff.

In the SOFTER_ADD and SOFTER_DROP procedures in the conventional soft handoff, the CE is in charge of the air interface with the mobile station, and the CE allocates channel resources according to the TSB's handoff processing command, and the channel of the mobile station is required to maintain a call. Channel resources between resources and CE must match.

However, in the SOFTER_ADD processing procedure, the CE transmits a resource allocation message (vs_sftr_ho_rps_ctl_msg) to the TSB and receives a response message from the TSB. If there is no response within the set time, the CE sends the resource allocation message to the TSB again. If the response message is not received after retransmitting the message three times, the CE releases the channel resource. At this time, the TSB transmits the HDM to the mobile station regardless of whether the CE response message is received upon receiving the resource allocation message, and determines that the handoff is successful when receiving the HCM from the mobile station. Therefore, in this case, there is a problem that the difference of the active pilot (ACTIVE PILOT) information between the TSB and CE occurs.

In addition, in the SOFTER_DROP processing procedure, since the TSB only delivers the tc_sftr_ho_complete_ctl_msg message to the CE when the handoff process with the terminal is completed, there is a problem in that the active pilot information between the TSB and the CE differs.

Due to this difference in active pilot information, a handoff failure occurs in the next soft handoff process, and a call drop occurs.

Accordingly, an object of the present invention is to solve the above-mentioned problems according to the prior art, and an object of the present invention is to optimize soft handoff by minimizing inter-sectoral handoff failure of a base station in a CDMA mobile communication system and resulting call drop. The present invention provides a method for processing soft handoff in a code division multiple access mobile communication system.

A feature of the soft handoff processing method in a code division multiple access mobile communication system according to the present invention for achieving the above object is a mobile communication system comprising a base station with CE and BCP, and a control station with TSB and CCP. A method for processing soft handoff in a computer, the method comprising: determining whether one drop or two drops are received in one active region Alpha or Gamma received a soft handoff instruction message from a transcoder and a selector bank of the control station. And if the result of the determination in the step is 1 drop or 2 drops, determining whether the active pilot is a drop pilot, and if the result of the determination in the step is the drop pilot, complete 1 drop or 2 drops to hand to the TSB. Reporting off completion and if the active pilot is a drop pilot, a Not Acknowledge (NAK) message is sent to the TSB. It comprises the step of transmitting.

1 is a flowchart illustrating a soft_ADD processing method among soft handoff processing methods in a conventional CDMA mobile communication system;

2 is a flowchart illustrating a soft_DROP processing method among soft handoff processing methods in a conventional CDMA mobile communication system;

3 is a flowchart of a first embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention;

4 is a flowchart of a second embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention;

5 is a flowchart of a third embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention.

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

10: mobile station, 20: base station,

30: control station.

Hereinafter, a preferred embodiment of a soft handoff processing method in a code division multiple access mobile communication system according to the present invention will be described with reference to the accompanying drawings.

3 is a flowchart of a first embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention.

As shown in FIG. 3, one drop (DROP) in one active area Alpha (Beta) or Gamma received a soft handoff instruction message from the transcoder and selector bank TSB of the control station 30. It is determined whether 2 drops (S101).

If the result of the determination in step S101 is 1 drop or 2 drops, it is determined whether the active pilot is a drop pilot (S103).

If it is determined in step S103 that the active pilot is not a drop pilot, one drop or two drops are completed and a handoff completion report is reported to the TSB (S105).

If it is determined in step S103 that the active pilot is a drop pilot, a Not Acknowledge (NAK) message is transmitted to the TSB.

In addition, it is determined whether the first active area Alpha or Beta Gamma received the soft handoff instruction message from the transcoder and selector bank TSB of the control station 30 is 1 ADD or 2 ADD. (S107).

As a result of the determination in step S107, if it is 1 or 2, it is determined whether the active pilot is an ether pilot (S109).

As a result of the determination in step S109, if the active pilot is not an ether pilot, one or two ethers are completed and a handoff completion report is reported to the TSB (S111).

If it is determined in step S109 that the active pilot is an ether pilot, a Not Acknowledge (NAK) message is transmitted to the TSB.

Then, it is determined whether or not 1 drop is 1 drop in one active area Alpha (Beta) Gamma received the soft handoff instruction message from the transcoder and the selector bank TSB of the control station 30 (S113). .

If the result of the determination in step S113 is 1 addition and 1 drop, it is determined whether the active pilot is a drop pilot (S115).

As a result of the determination in step S115, if the active pilot is not a drop pilot, it is determined whether the active pilot is an ether pilot (S117).

As a result of the determination in step S117, if the active pilot is not an ether pilot, one adds one drop and one drop and reports a handoff completion to the TSB (S119).

If it is determined in step S119 that the active pilot is the ether pilot, a Not Acknowledge (NAK) message is transmitted to the TSB.

Therefore, one drop or two drop commands cannot be generated in one active state, but if it is not the current active pilot drop, the handoff completion report is made as if the drop handoff was made.

Here, one adder, two adders or one adder and one drop are handled only in the normal case.

4 is a flowchart of a second embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention.

As shown in FIG. 4, in the two-active regions Alpha and Beta (Alpha, Gamma) (Beta, Gamma) that receive a soft handoff instruction message from the transcoder and selector bank TSB of the control station 30. It is determined whether one drop (DROP) or two drops are two active (S201).

If 1 drop or 2 drop is 2 active as a result of the determination in step S201, the 1off or 2 drop is completed and the handoff completion report is reported to the TSB (S203).

If it is determined in step S201 that one drop (DROP) or two drops are not two active, a NAK (Not Acknowledge) message is transmitted to the TSB.

In addition, in the two active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma), which have received a soft handoff instruction message from the transcoder and selector bank (TSB) of the control station 30, one adder (ADD) or It is determined whether it is 2 Ether (S205).

If the result of the determination in step S205 is 1 or 2, the handoff completion report is reported to the TSB (S207).

If it is determined in step S205 that it is not 1 or 2, it transmits a NAK (Not Acknowledge) message to the TSB.

In addition, in the two active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and the selector bank (TSB) of the control station 30, it is 1 add and 1 drop. Determine (S209).

If the result of the determination in step S209 is 1 addition and 1 drop, it is determined whether the drop is an active pilot (S211).

If it is determined in step S211 that the drop is an active pilot, the ether determines whether it is an active pilot (S213).

If the result of the determination in step S213 is an active pilot, one adds one drop and one drop and reports a handoff completion to the TSB (S215).

If it is determined in step S213 that the Ether is not an active pilot, a Not Acknowledge (NAK) message is transmitted to the TSB.

Therefore, in the 2-active area, it handles both 1 drop and 2 drop commands except when 2 active drops in 2 drops, and 1 and 2 add commands except when 2 active adds 2 active. To process.

5 is a flowchart of a third embodiment showing a soft handoff processing method in a code division multiple access mobile communication system according to the present invention.

As shown in FIG. 5, in the three active regions (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank (TSB) of the control station 30 The handoff completion report is reported to the TSB by completing one drop (DROP) or two drops (S301).

In addition, in the three active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and the selector bank (TSB) of the control station 30, one adder (ADD) or Complete the 2 adder and report the handoff completion to the TSB (S303).

In addition, one add and one drop in the three active areas Alpha and Beta (Alpha, Gamma) and Beta and Gamma received the soft handoff instruction message from the transcoder and selector bank TSB of the control station 30. Complete and report the handoff completion to the TSB (S305).

Therefore, in the three-active area, all cases are processed according to the TSB instruction.

As described above, the present invention can minimize the soft handoff failure due to the mismatch of active pilot state information between the lower processor and the main processor in the CDMA mobile communication system, thereby improving the quality of mobile communication service by minimizing call drop. It has an effect.

Claims (3)

A soft handoff processing method in a mobile communication system comprising a base station with CE and BCP and a control station with TSB and CCP, Determining whether it is one drop or two drops in one active region Alpha or Gamma received a soft handoff instruction message from a transcoder and a selector bank of the control station; Determining whether the active pilot is a drop pilot when the result of the determination in the step is 1 drop or 2 drops; If the active pilot is not a drop pilot as a result of the determination in the step, completing one drop or two drops to report a handoff completion to the TSB; Transmitting a Not Acknowledge (NAK) message to the TSB if the active pilot is a drop pilot as a result of the determination in the above step; Determining whether it is one ether or two ether in one active area (Alpha) (Beta) (Gamma) receiving a soft handoff instruction message from a transcoder and a selector bank of the control station; Judging whether the active pilot is an Ether pilot if the result of the determination in the step is 1 Ether or 2 Ether; If the active pilot is not an ether pilot as a result of the determination in the step, completing one or two adders to report a handoff completion to the TSB; Transmitting a NAK message to the TSB if the active pilot is an ether pilot as a result of the determination in the above step; Determining whether one drop and one drop in one active area Alpha and Gamma received a soft handoff instruction message from a transcoder and a selector bank of the control station; Judging whether the active pilot is a drop pilot when the result of the determination in the step is 1 addition and 1 drop; Determining whether the active pilot is an ether pilot if the active pilot is not a drop pilot; If the active pilot is not an ether pilot as a result of the determination in the step, completing 1 add and 1 drop to report a handoff completion to the TSB; And transmitting a NAK message to the TSB if the active pilot is an ether pilot. A soft handoff processing method in a mobile communication system comprising a base station with CE and BCP and a control station with TSB and CCP, Determining whether 1 drop or 2 drop is 2 active in the 2 active areas Alpha and Beta (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank of the control station. Wow; If the 1 drop or 2 drop is 2 active as a result of the determination in the step, completing 1 drop or 2 drop and reporting a handoff completion to the TSB; Transmitting a Not Acknowledge (NAK) message to the TSB if one drop or two drops are not active as a result of the determination in the step; Determining whether it is one or two adders in the two active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank of the control station; Making a handoff completion report to the TSB if it is 1 or 2 adder as a result of the determination in the step; Transmitting a NAK message to the TSB if the determination result is not at 1 or 2; Determining whether it is one adder or one drop in a two active region (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) that receives a soft handoff instruction message from a transcoder and a selector bank of the control station; Judging whether the drop is an active pilot when the result of the determination in the step is 1 addition and 1 drop; Determining whether the ether is an active pilot if the drop in the step is an active pilot; If the result of the determination at the step is an active pilot, completing 1 add and 1 drop and reporting the handoff completion to the TSB; And transmitting the NAK message to the TSB if the Ether is not the active pilot. A soft handoff processing method in a mobile communication system comprising a base station with CE and BCP and a control station with TSB and CCP, Complete one or two drops in the three active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank of the control station to complete the handoff to the TSB. Making a report; Complete the 1-off or 2-addition in the 3 active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank of the control station to complete the handoff to TSB. Making a report; Complete one add and one drop in the three active areas (Alpha, Beta) (Alpha, Gamma) (Beta, Gamma) received the soft handoff instruction message from the transcoder and selector bank of the control station to complete the handoff to the TSB. A soft handoff processing method in a code division multiple access mobile communication system, comprising the step of reporting.