JP3562525B2 - Location registration control method and mobile station device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce battery depletion caused by the continuous failure of location registration processing. <P>SOLUTION: In the location registration processing of the mobile station of a CDMA (Code Division Multiple Access) system, when a registration failure is authenticated (a step S106), idle handoff is inhibited (a step S107) and it is transferred to a location registration wait sleep state (a step S108 and a state ST10) that allows the transmitting and the receiving operation of the mobile station to be paused at predetermined intervals. At the expiration time of a sleep timer set in the step S108 (see another drawing), a step of restarting the location registration processing based on a predetermined criterion and the step of capturing a new pilot signal at the restart time are included. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mobile station in a mobile communication system using a code division multiple access (CDMA) system as an access system when performing position registration processing for a wireless base station in an area where a mobile station device is located. The present invention relates to a control method on the device side and a mobile station device using the same, and is particularly suitable for power saving of the mobile station device.
[0002]
[Prior art]
When receiving a signal from a base station, a CDMA mobile station apparatus despreads a spectrum-spread signal and demodulates the original signal. For this reason, it is necessary to perform a synchronization process for matching the phase of a pilot pseudo-noise code (PN: Pseudo Noise) code, which is a spreading code, to the base station side.
[0003]
This synchronization processing is divided into two stages: acquisition of a pilot signal and maintenance of synchronization. Acquisition is generally based on a correlation operation, and is a process of multiplying a received signal while shifting the replica PN code in units of spreading chips and determining whether the integrated value is equal to or greater than a threshold value. If the replica PN code and the PN code on the base station side are not synchronized, no peak occurs in the integrated value, so that the search is continued by changing the phase of the replica PN code. In a typical CDMA system, the code length of a pilot PN code is 32768, which is 2 to the 15th power. Since this phase space is searched for, a high speed of initial acquisition is required. On the other hand, the synchronization holding refers to a process of maintaining the synchronization in the phase within the chip after capturing the spread chip synchronization.
[0004]
A plurality of base stations or sectors of a mobile communication system are arranged by selecting the phases of their respective spreading codes so as to be different from each other. In the above representative example, they are arranged apart from each other in a relationship of an integral multiple of 64 chips. After the synchronization processing, the mobile station apparatus can adjust the code phase of the despreading, check the strength of another pilot signal, and switch to a better pilot signal (handoff). Handoff performed during standby reception is called idle handoff.
[0005]
Now, the mobile station device that has completed the synchronization process performs the location registration process next. This location registration process is achieved by exchanging messages with the base station. This allows the network to call the mobile station device. Since the location registration process involves transmission, if it is performed frequently, traffic to the network increases, and the battery of the mobile station device is consumed. Therefore, its execution needs to be minimized.
[0006]
The powered-on mobile station apparatus performs the synchronization processing on the pilot signal as described above, receives the broadcast information, and determines whether or not the area in which the own station is located requires new location registration processing. If the location registration area matches the location registered area stored in the mobile station device (in some cases, it is listed), the location registration request message is not transmitted.
[0007]
When the mobile station device leaves the above area, handoff is performed to the base station in the next area to enter.
[0008]
[Problems to be solved by the invention]
A mobile station apparatus of the CDMA system exchanges messages on a downlink (downlink signal) established by capturing and synchronizing a pilot signal and on an uplink (uplink signal) transmitted by the mobile station apparatus. Unfortunately, an environment in which the reach of the upper and lower signals is unbalanced may appear due to terrain conditions and the like. That is, a downlink signal from a base station to which an uplink signal does not reach may be continuously and effectively received by the mobile station device. In particular, in a situation where the reception level is low, the probability that the base station to which the uplink signal does not reach is captured or the base station is shifted to the base station by idle handoff increases.
[0009]
When the location registration processing is required for the base station, the transmission of the mobile station device does not reach, and the location registration processing fails. However, since a valid downlink signal is received, the position registration process continues, and the battery is wasted.
[0010]
An object of the present invention is to provide a position registration control method capable of saving power of a mobile station device when performing position registration processing for a base station and reducing battery consumption, and a mobile station device using the same. .
[0011]
[Means for Solving the Problems]
To achieve the above object, the present invention receives the pilot signals transmitted from different sectors of PN phase, a transceiver for transmitting signals to the plurality of sectors, received by the transceiver unit has a CDMA modem unit for demodulating a pilot signal, based on the strength of the pilot signal demodulated by the CDMA modem unit, and a control unit for controlling to perform location registration processing to a better sector, the said control unit If the location registration processing based on the strength of the pilot signal fails, the PN phase of the sector in which the location registration processing failed is captured in one direction, and the PN phase is captured. The mobile station device is characterized in that the mobile station device controls to perform a location registration process .
[0012]
Further, the present invention receives the pilot signals transmitted from different sectors of PN phases, demodulates the received pilot signal, based on the intensity of the demodulated pilot signal, a better When the position registration process is performed on the sector and the position registration process based on the strength of the pilot signal fails, the sector in which the PN phase is shifted in one direction from the PN phase of the sector in which the position registration process failed is captured. A position registration control method characterized by performing a position registration process on a captured sector .
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of a configuration of the mobile station device according to the first embodiment of the present invention. In the figure, reference numeral 31 denotes a transmitting / receiving unit for transmitting and receiving a radio signal. Reference numeral 32 denotes a CDMA modem unit for performing demodulation by despreading and performing spread modulation, and has a built-in local PN code generator 321 for base station synchronization processing. Reference numeral 33 denotes a telephone unit for performing display to a user, input of a user operation, output of a reception signal, input of a transmission signal, and the like. A control unit 30 controls the operations of the transmission / reception unit 31, CDMA modem unit 32, and telephone unit 33. Reference numeral 34 denotes a sleep timer for controlling the active state and the idle state of the operation of the control unit 30.
[0022]
The transmission message to the base station is input from the control unit 30 to the CDMA modem unit 32 in the form of digital data. The section 32 forms a frame in a wireless section based on the input transmission message, and further generates a baseband signal obtained by spreading and modulating the frame. The baseband signal is input to the transmission / reception unit 31, where it is subjected to carrier modulation and amplification, and output to a wireless section.
[0023]
The received message from the base station is tuned and detected by the transmission / reception unit 31 and input to the CDMA modem unit 32. Then, the same section 32 performs despreading synchronization processing and the like, and inputs the result to the control section 30 in the form of digital data. The control unit 30 controls the operation of the mobile station device in accordance with the operation of the user according to the received message. The control includes stopping and restarting the operation of each unit.
[0024]
The reception level is detected by the transmission / reception unit 31 and input to the control unit 30. The control unit 30 is realized by a microcomputer (not shown), and the position registration control method of the present invention is realized by a program incorporated in the microcomputer.
[0025]
FIG. 1 is a flowchart of a location registration operation according to the first embodiment of the present invention. 4 shows a flowchart after power-on of the mobile station device. The location registration process after the idle handoff may be started from step S103 in FIG.
[0026]
First, the mobile station device that has been powered on newly acquires a pilot signal and determines the success or failure (steps S101 and S102). If the acquisition has failed, the state shifts to the out-of-service state (ST00) and the processing exits from the position registration processing. If the acquisition is successful, it is determined whether new location registration is necessary based on the notified area information (step S103), and if necessary, location registration is performed (step S104). At this time, if it is determined that the area has already been registered, the processing shifts to the intermittent reception state (ST20), which is a normal standby state, and exits the position registration processing.
[0027]
If the location registration has been performed, success or failure is determined (step S105), and if successful, the intermittent reception state ST20 is set. Here, the failure due to the failure of the process in step S104 is performed when the number of repetitions of the random access sequence instructed by the base station is completed until the predetermined response cannot be received. If a failure is determined in step S105, it is determined whether the completion of step S104 due to the failure has reached a predetermined number n (step S106). If not, the process returns to step S104 and repeats position registration.
[0028]
If the predetermined number n has been reached, it is determined that the current state is that the reception of the downlink signal is valid, but the transmission of the mobile station apparatus does not reach the base station. In this state, the present embodiment performs the following processing in order to prevent the location registration processing from continuing and increasing the battery consumption. First, the mobile station device prohibits idle handoff of its own station (the reason will be described later), and turns on the out-of-service display of the telephone unit 33 (step S107). Next, the sleep timer 34 is set to measure a pause period, and after stopping the transmission and reception operations of the mobile station device, the control unit 30 transitions to the sleep state. The transmission and reception are stopped by stopping the transmission / reception unit 31 and the CDMA modem unit 32. The sleep of the control unit 30 uses a general sleep function provided in the microcomputer. This sleep state is automatically canceled when the sleep timer 34 expires. In the present embodiment, this sleep state is referred to as a position registration waiting sleep state (ST10).
[0029]
Next, a return process from the sleep state will be described. FIG. 2 is a flowchart of a location registration operation started in the location registration waiting sleep state according to the first embodiment.
[0030]
The control unit 30 restarted when the sleep timer 34 expires activates the transmission / reception unit 31 and the CDMA modem unit 32 and acquires the current reception level (step S201). Then, it is determined whether or not the obtained reception level is equal to or higher than a predetermined threshold (step S202). If the reception level is low, the sleep timer 34 is set again (step S208), and the mode shifts to the position registration waiting sleep state (ST10). I do. If the reception level is equal to or higher than the threshold value, it is determined that there has been a change in the unbalanced state of the arrival area of the uplink and downlink radio signals, and the location registration operation is started again. That is, pilot acquisition is newly performed, and the success or failure of the acquisition is determined (steps S203 and S204). If the acquisition fails, the prohibition of the idle handoff is released (step S209), and the state shifts to the out-of-service state (ST00).
[0031]
If it can be acquired, the necessity of location registration is determined (step S205). If it is unnecessary, the prohibition of the idle handoff is released, the out-of-service display is turned off (step S210), and the mode shifts to the intermittent reception state (ST20). I do. If an area requiring location registration is captured, location registration is performed (S206). Next, the success or failure is determined (step S207), and if successful, the process proceeds to the intermittent reception state (ST20) via the step S210.
[0032]
If the location registration has failed, the process returns to the location registration waiting sleep state via step S208. According to the control method shown in FIGS. 1 and 2, the consumption of the battery during the sleep period is reduced as compared to when the location registration process is continued.
[0033]
By the way, in the present embodiment, the idle handoff is prohibited at the first transition to the position registration waiting sleep state, for the following reason.
[0034]
The mobile station device always measures the pilot strength of another base station (other sector in a typical system) from the stage where pilot acquisition is completed. And it is designed to perform handoff to a better base station (sector). In a situation where the mobile station apparatus has failed in the location registration processing due to an imbalance in the reach of the uplink and downlink, the probability of handoff to the failed base station is higher than other base stations. If idle handoff is not prohibited, even if a new pilot is acquired in step S102 in FIG. 2, the probability that handoff will occur before location registration is performed in step S104 and location registration will be continued to a base station that eventually fails will result. Is high. Therefore, once the failure of the location registration process is recognized, idle handoff is prohibited as abnormal processing, and the probability of location registration to another base station is increased so as not to fail again.
[0035]
A second embodiment in which this effect is further improved will be described below. FIG. 4 is a flowchart of a location registration operation according to the second embodiment. However, it is described from the stage when the power is turned on and the acquisition of the pilot signal is completed, or the state after the idle handoff. The configuration of the mobile station device implementing the present embodiment is the same as that shown in FIG. In the present embodiment, first, it is determined whether a new location registration is necessary, and if necessary, the location registration is performed, and the success or failure of the location registration is determined (steps S401, S402, S403). When the position registration is unnecessary or when the position registration is successful, the mode shifts to the intermittent reception state (ST20). If it is determined in step S403 that the location registration processing has failed, in the present embodiment, the idle handoff is immediately prohibited and the out-of-service display is turned on (step S405).
[0036]
In this state, the control unit 30 instructs the CDMA modem unit 32 to change the state value of the local PN code generator 321 for despread code synchronization to a state value after a predetermined time has elapsed, and to generate the generated PN code. The code phase is forcibly shifted (step S406). Further, a new pilot signal is searched from the shifted phase position in the phase leading direction (one direction) (step S407). FIG. 5 is a schematic diagram for explaining the operations of steps S406 and S407. The phase of the PN code is represented by a position on the circumference 50 shown by a dotted line. Assuming that the initially captured sector is 51, the forced shift of the phase of the PN code in step S406 is performed as indicated by an arrow 52. Then, the search in one direction in step S407 is performed as indicated by an arrow 53, and another sector such as the illustrated 54 is captured. In the above series of operations, when the transmission of the mobile station device does not reach the 51 sector, the idle handoff to this sector is prohibited, and another sector is newly acquired. The phase width for forcibly shifting has a trade-off relationship between the probability of capturing another sector and the battery consumption, and needs to be optimized. If the acquisition of the new pilot signal fails in step S407, the prohibition of the idle handoff is canceled and the mobile terminal shifts to the out-of-service state, which is omitted in FIG. 4 (steps S203, S204, and S209 in FIG. 2). , Equivalent to the path in state ST00). When a new pilot is captured, the necessity of the location registration process is determined, and if unnecessary, the prohibition of the idle hand-off is released, the out-of-service display is turned off, and the mode is shifted to the intermittent reception state (steps S408, S413, S413). State ST20).
[0037]
If it is determined in step S408 that the location registration process is necessary, location registration is performed, and the success or failure is determined (steps S409 and S410). If it is determined in step S410 that the location registration has succeeded, the prohibition of the idle hand-off is released, the out-of-service display is turned off, and then the mode shifts to the intermittent reception state.
[0038]
If it fails again, a determination is made as to whether or not the pilot synchronization search and capture range has made one round on the circumference representing the phase of the PN code indicated by 50 in FIG. 5 (step S411). If not, the process returns to step S406, and the process following the forced phase shift is repeated. After one round, the sleep time is set in the sleep timer 34, the operations of the transmission / reception unit 31, and the CDMA modem unit 32 are stopped, and the control unit 30 shifts to the sleep state (ST10) (step S412). In the present embodiment, the control method before shifting to the sleep state is slightly complicated, but it is possible to improve the probability of acquiring a base station (sector) different from the base station (sector) whose location registration has failed. it can. Note that the process of returning from the location registration waiting sleep state ST10 is the same as that of the first embodiment. That is, the location registration after the return is performed for the base station whose reception level is equal to or higher than the predetermined threshold. Obviously, setting the threshold higher will reduce battery consumption, but will also reduce location registration opportunities. It is desirable that this threshold is optimized according to the situation. An embodiment in consideration of this point will be described below.
[0039]
FIG. 6 is a diagram illustrating an example of a configuration of the mobile station device according to the third embodiment. A threshold value calculation unit 301 for inputting a reception level from the transmission / reception unit 31 is added to the configuration shown in FIG. Further, an offset table 302 connected to the threshold value calculation unit 301 is added. The control method implemented in the control unit 30 of FIG. 6 is characterized in that the threshold value is changed according to the situation. FIG. 7 is a flowchart of a location registration operation according to the third embodiment. FIG. 7 differs from the first embodiment in step S600 inserted between steps S107 and S108. In step S600, the threshold used when returning from the sleep state before shifting to the sleep state (ST10) is updated based on the current reception level. The updated value is obtained by adding a predetermined offset value to the current reception level. This processing is performed by the threshold value calculation unit 301 in FIG. The threshold calculator 301 determines an offset value to be added with reference to the offset table 302 based on the reception level. The contents of the offset table are, for example, as follows. FIG. 8 is a graph in which the horizontal axis 71 is the reception level and the vertical axis 70 is the offset value, and is a diagram for explaining an example of the offset value in step S600 of the third embodiment. For example, the offset value when the threshold value is fixed is stored as indicated by a dotted line 72. A dotted line 72 is a straight line having a slope of -1 in a region where the reception level is equal to or less than β. When the reception level is β, the offset value is zero, and when the reception level exceeds β, it is negative infinity. That is, when the reception level at the time of return is equal to or higher than β, the position registration operation is always started. Next, in the case where the contents of the table are as shown by the solid line 73, in the area where the reception level is low (below γ), the position registration is performed only when α [dB] is improved compared to the position registration failure. In order to improve the effect of reducing battery consumption, it is effective to set the values of β and γ to be somewhat high. However, in order to keep track of the opportunity of the position registration, a mechanism that reacts more sensitively to changes in the surrounding conditions is required as shown by a solid line 73. Also, since the threshold value is updated again when the location registration fails when returning from the sleep state, the return processing is as shown in FIG. FIG. 9 is a flowchart of the location registration operation started in the location registration waiting sleep state according to the third embodiment, in which step S900 is added compared to the first and second embodiments. As described above, according to the third embodiment, the threshold value for restarting location registration can be made variable depending on the reception level, which is advantageous for optimization.
[0040]
As described above, in the present embodiment, when it is determined that the location registration processing has failed, the step of prohibiting the idle handoff of the mobile station apparatus is performed by the base station (or sector) that is likely to fail again. The probability of performing location registration can be reduced. In the state where the idle handoff is prohibited, if the location registration fails, the step of suspending the transmission and reception operations of the mobile station apparatus at a predetermined interval and the step of resuming the location registration processing based on a predetermined standard when the pause state expires. Since the step includes a step, the number of location registrations can be suppressed. In addition, since the step of restarting includes a step of newly acquiring a pilot signal, a base station (sector) different from the previously failed base station (sector) is included. ) Is captured, and the probability of performing position registration with the other base station (sector) is improved.
[0041]
Therefore, there is an effect that the consumption of the battery due to the continuation of the location registration processing is reduced, and the power saving of the mobile station apparatus can be performed.
[0042]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the power saving of the mobile station apparatus at the time of performing a location registration process with respect to a sector can be aimed at, and the location registration control method which can reduce battery consumption, and the mobile station apparatus using the same can be obtained.
[Brief description of the drawings]
FIG. 1 is a flowchart of a location registration operation according to the first embodiment.
FIG. 2 is a flowchart of a location registration operation started in a location registration waiting sleep state according to the first embodiment;
FIG. 3 is an example of a configuration of a mobile station device according to the first embodiment.
FIG. 4 is a flowchart of a location registration operation according to the second embodiment.
FIG. 5 is a diagram illustrating the operation of steps S406 and S407 in FIG.
FIG. 6 is an example of a configuration of a mobile station device according to a third embodiment.
FIG. 7 is a flowchart of a location registration operation according to the third embodiment.
FIG. 8 is a diagram illustrating an example of an offset value in step S600 according to the third embodiment.
FIG. 9 is a flowchart of a location registration operation started in a location registration waiting sleep state according to the third embodiment.
[Explanation of symbols]
30: control unit 31: transmission / reception unit,
32: CDMA modem unit 33: Telephone unit 34: Sleep timer 301: Threshold calculation unit 302: Offset table 321: PN code generator 50: PN code phase 51: Example of first captured sector 52: Next capture possible Example of sector 53: search direction 70: vertical axis (offset value)
71: horizontal axis (reception level)
72: Example of offset value based on reception level (dotted line)
73: Example of offset value based on reception level (solid line)

Claims (8)

A transceiver for receiving a pilot signals transmitted from different sectors of PN phases, and transmits the signal to the plurality of sectors,
A CDMA modem unit for demodulating a pilot signal received by the transceiver unit,
A control unit that controls to perform location registration processing to a better sector based on the strength of the pilot signal demodulated by the CDMA modem unit ;
When the position registration processing based on the strength of the pilot signal fails, the control unit captures a sector in which the PN phase is shifted in one direction from the PN phase of the sector in which the position registration processing failed, and the captured A mobile station device which controls to perform a location registration process for a sector . A transmitting / receiving unit that receives pilot signals respectively transmitted from a plurality of sectors having different PN phases and transmits signals to the plurality of sectors;
A CDMA modem unit for demodulating a pilot signal received by the transmitting / receiving unit;
A control unit that controls to perform idle handoff to a better sector based on the strength of the pilot signal demodulated by the CDMA modem unit;
The control unit performs position registration processing on the sector that has been idle handed off, and when the position registration processing has failed, prohibits idle handoff and shifts the PN phase in one direction from the PN phase of the sector in which the position registration processing has failed. A mobile station device that performs control so as to acquire a sector that has been acquired and to perform location registration processing on the acquired sector. The mobile station device according to claim 1 or 2,
The mobile station apparatus characterized in that the phase shifts in one direction means that the phase is advanced. The mobile station device according to claim 1 or 2,
The control unit, when the location registration processing for the sector has failed a plurality of times, captures a sector whose PN phase is shifted in one direction from the PN phase of the sector for which the location registration processing has failed, and A mobile station device that controls to perform a location registration process on a sector that has been set. The mobile station device according to claim 1, wherein:
The mobile station device, wherein when the location registration processing for the plurality of sectors fails, the control unit suspends the transmission / reception unit for a predetermined time. The mobile station device according to claim 5, wherein
The mobile station device, wherein after suspending the transmission / reception unit, the control unit restarts the location registration process when a reception level is equal to or higher than a threshold. The mobile station device according to claim 6, wherein
The mobile station device, wherein the threshold value is a value obtained by adding a reception level when a location registration process cannot be performed and an offset value based on the reception level. Receiving pilot signals transmitted from a plurality of sectors having different PN phases,
Demodulating the received pilot signal,
Based on the strength of the demodulated pilot signal, perform a location registration process to a better sector,
If the position registration processing based on the pilot signal strength fails, the sector whose PN phase is shifted in one direction from the PN phase of the sector for which the position registration processing failed is acquired, and the position is determined with respect to the acquired sector. A location registration control method characterized by performing a registration process.

Images