KR100735301B1 - Set maintenance method and apparatus for a mobile terminal in a mobile communication - Google Patents

Abstract

The present invention relates to an apparatus and a method for managing a plurality of sets in a mobile communication system, and to adjust the range or search rate of the set to be searched according to the user's mobility.

In order to achieve the object of the present invention, the controller of the pilot channel searcher of the mobile terminal determines whether the mobile terminal moves based on the received GPS signal, and if the mobile terminal does not move, adjusts a set search range. It is done.

SET MAINTENANCE, CDMA, SERCHER, PILOT

Description

A set management method of a mobile terminal in a mobile communication system and a pilot channel searcher using the same {SET MAINTENANCE METHOD AND APPARATUS FOR A MOBILE TERMINAL IN A MOBILE COMMUNICATION}

1 is a flow chart illustrating a set management method of a mobile terminal (MS) in a mobile communication system according to the prior art,

2 is a diagram illustrating a search period when performing set management of an MS according to the prior art;

3 is a flowchart illustrating a basic concept of a set discovery method performed by an MS according to an embodiment of the present invention;

4 is a flowchart illustrating a set search method in which an MS is aquatic according to an embodiment of the present invention;

5 is a diagram illustrating a method of adjusting a range of a set to be searched according to a discovery mode set by an MS according to a first embodiment of the present invention;

6 is a diagram illustrating a method for adjusting a discovery period according to a discovery mode in which an MS is configured according to a second embodiment of the present invention;

7 illustrates a configuration of a pilot channel searcher according to the present invention;

8 is a block diagram illustrating a controller in accordance with an embodiment of the present invention.

The present invention relates to a method and apparatus for searching for a neighboring base station in a mobile communication system. In particular, a pilot off divided into a plurality of sets according to a movement of a mobile terminal in a code division multiple access (TDC) communication system. The present invention relates to a set management method of a mobile terminal for monitoring sets and efficiently adjusting a search speed or period of each set, and a pilot channel searcher using the same.

In general, mobile communication is intended to enable a call while a subscriber is moving at a high speed over a large area. A representative system of such a mobile communication system is a cellular system. The cellular system is a concept proposed to overcome the limitations of the service area and the subscriber capacity of the conventional mobile communication system. The cellular system is divided into several small areas, or cells, to be identical in two cells far enough apart from each other. The use of frequency bands means spatial reuse of frequencies. The first technology of such cellular systems is analog such as Advance Mobile Phone System (AMPS) and Total Access Communication Services (TACS), which is called first generation mobile communication. The first generation of mobile communication systems has made it difficult to accommodate the rapidly increasing subscribers of mobile communication services, and the development of technology has increased the demand for various services as well as previous voice services. Due to these demands, digital 2nd generation mobile communication, which is more advanced than 1st generation mobile communication, has emerged. Unlike the analog system, the second generation mobile communication system digitalizes an analog voice signal, performs a voice encoding, and uses a digital modulation and demodulation method, and uses a frequency of 800 MHz. The multiple access method uses a time division multiple access (TDMA) method and a code division multiple access (CDMA). In the second generation mobile communication system, voice services and low-speed data services are provided, and there are IS-95 (CDMA), IS-54 (TDMA), and GSM (Global System for Mobile communication) systems in the United States. In addition, PCS (Personal Communication Services) system is classified as a 2.5 generation mobile communication system, and uses a frequency of 1.8 ~ 2GHz band. These second generation mobile communication systems have been established for the purpose of increasing the efficiency of mobile communication systems while providing voice services to users.

In a typical CDMA mobile communication system, each base station has the same spreading code and has a different delay for each base station, that is, a PN code sequence (hereinafter referred to as a pilot channel signal). ") Is transmitted to the mobile terminal, and the mobile terminal searches for the pilot channel signal to recognize a specific base station and synchronizes with the base station before performing communication. In addition, in such a CDMA system, a mobile station (MS) corresponds to a multi-path, and handoff is performed well when moving to another cell, so that current call stability is maintained to maintain call stability. It is necessary to continuously monitor the pilot channel signal strength (Ec / Io) of the communicating base station and neighboring base stations. In the CDMA system, a total of 512 pilot offsets can be used by base stations, and one pilot offset is allocated to each base station. The CDMA system manages these pilot offsets into four sets: an active set, a candidate set, a neighbor set, and a residual set.

The active set (hereinafter referred to as "A set") is a set of pilot offsets of base stations to which the MS and traffic channel are currently assigned or the MS is receiving a sync channel or paging channel.

The neighbor set (hereinafter referred to as "N set") is a set of pilot offsets of neighboring base stations of the base station belonging to the A set, and the base station belonging to the A set transmits a message to the MS.

The candidate set (hereinafter, referred to as "C set") is a set of pilot offsets in which the strength of the pilot signal among the N sets is larger than a predetermined threshold value and is continuously monitored and updated by the MS.

The remaining set (hereinafter referred to as "R set") is a set of remaining pilot offsets not included in the three sets such as A set, N set, and C set described above.

In addition, the MS monitors the pilot signals of the four sets and updates the set according to the result, or makes a handoff request to the base station.

The MS applies a constant window for a particular pilot offset to measure the strength of the pilot signal received in multiple paths, add them all together, and regard it as the energy for that pilot signal.

This series of tasks is called a pilot search, and a searcher provided in the modem of the mobile terminal performs this task. The periodic search updates the PN position and maintains the call quality by having the rake receiver receive data through the updated PN position.

Set management in a general CDMA mobile communication system performs set management by setting A set, C set, N set, and R set specified in the standard. The process of searching for a neighbor base station in a mobile terminal according to the prior art is shown in FIG. This will be explained with reference.

1 is a flowchart illustrating a set management method of a mobile terminal (MS) in a mobile communication system according to the related art.

First, in step 100, the MS searches all lists of A sets included in a message such as a channel assignment message (CAM) and a handoff direction message (HDM) received from an adjacent base station. Next, in step 102, all of the C sets included in the A set but whose reception strength of the pilot signal falls below a predetermined threshold value are searched for.

In step 104, all N sets included in a message such as a neighbor list update message (NLUM) and a neighbor list message (NLM) received from the base station are searched. The process is repeated over and over again.

Although FIG. 1 illustrates a method for searching N sets several times at a time, according to the implementation method, both A set and C sets are searched and N sets are searched one by one, so that the MS can manage the set.

If the MS performs set management by searching N sets one by one, in step 100 of FIG. 1, all A sets are searched, in step 102, all C sets are searched, and in step 104, only one N set is searched. Then, steps 100 and 102 are performed again. Then, in step 104, the second N set is searched and the process proceeds to step 100 again. After repeating the above process and searching for all the N sets, the R set is searched for one, and the search index of N sets is reset to "0" in order to search the N sets again from the beginning. And proceed to step 100 again.

1 illustrates the most basic prior art. This search operation is repeated periodically until the call state after the MS receives the pilot signal.

2 is a diagram illustrating a search period when performing set management of an MS according to the related art. In FIG. 2, A set 0 is first measured at T1, and a section until measured again at T2 is called a search period of A set 0 of the MS.

2 illustrates a search period of the MS assuming three A sets, two C sets, and four N sets. If the number of preset sets is changed as described above, the search period will also vary.

In general, the MS manages multiple sets according to the pilot signal and periodically updates the energy or PN location information of the pilot signal when the user is stationary or mobile (i.e. multipath environment or fading environment). To ensure high call quality.

The set search according to the conventional set management shown in FIG. 1 searches for a certain number of predetermined sets at regular intervals regardless of whether the user moves. Since 90% or more of the time that the actual user uses the mobile terminal is a stationary stable state rather than a multipath or fading state, set management of the same pattern is inefficient, and thus a more efficient set management method is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus and method for monitoring a pilot off set divided into a plurality of sets by a mobile terminal in a mobile communication system, determining mobility and efficiently managing each set according to the determination result. .

Another object of the present invention is to determine the mobility of the mobile terminal based on the GPS signal received from the base station in the mobile communication system, if there is no movement of the mobile terminal according to the determination result of the set of the search period or the set to search It is to provide an apparatus and method for saving the resources of the mobile terminal by reducing the number.

Another object of the present invention is to determine whether or not the mobile terminal of the mobile communication system based on the GPS signal received from the GPS satellites, if there is no movement of the mobile terminal according to the determination result set of the search period or the set to search It is to provide an apparatus and method for saving resources of a mobile terminal by reducing the number of.

An apparatus for achieving the above objects of the present invention is a pilot channel searcher of a mobile terminal that receives pilot channel signals from a plurality of base stations of a mobile communication system and performs set management for a set of pilot offsets of each base station. A despreader for despreading the I and Q components of the pilot channel signal received through the antenna from the base station using predetermined PN codes, a PN generator for generating the PN codes according to a predetermined control signal, and the despreading And a non-coherent accumulator that accumulates the coherent accumulator, an energy calculator that calculates energy values of the accumulated signals, an non-coherent accumulator that accumulates the energy value calculated for a predetermined time, and A sorter that aligns the average energy value for pilot offsets, and periodically GPS And a controller for receiving a (Global Positioning System) signal to check whether the mobile terminal has moved, and if the mobile terminal has moved, adjusting a set search range.

A method for achieving the above object of the present invention, in the set management method in a mobile terminal of a mobile communication system, periodically receiving a Global Positioning System (GPS) signal, based on the received GPS signal the mobile terminal Determining whether to move, and if the mobile terminal does not move, adjusting a set search range.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same components in the drawings represent the same numerals wherever possible. Specific details are set forth below, which are provided to aid a more general understanding of the present invention. In describing the present invention, when it is determined that description of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

In an embodiment of the present invention, the MS determines whether it is currently moving by using a GPS signal received from a GPS (Global Positioning System) satellite to change a search rate and a set range to be searched. If there is no movement of the MS for a certain period of time, according to an embodiment of the present invention, it is determined that stability is high, thereby reducing the range of the set to be searched or increasing the set search period, and if there is movement, handoff without degrading call quality even at high speed. Search for the set in the normal search mode according to the prior art, which can perform.

In the embodiment of the present invention, adjusting the range of the set to be searched according to the moving state measured by the MS will be described as the first embodiment, and adjusting the set search period according to the moving state will be described as the second embodiment. .

3 is a flowchart illustrating a basic concept of a set search method performed by an MS according to an embodiment of the present invention.

In step 300, the MS receives GPS signals from the GPS satellites at regular intervals. In step 302, the MS periodically determines whether the current MS moves by using the received GPS signal. In step 304, when the MS determines that there is no movement for a predetermined time, the MS proceeds to step 306 and the search mode proposed by the present invention. Change the set search mode. On the other hand, if there is a movement of the MS in step 304, the flow proceeds to step 308 to search for a general search mode, that is, all active sets, candidate sets, and neighbor sets around the MS.

The predetermined time in step 304 of FIG. 3 serves as a criterion for determining whether the MS is stable. If there is no movement of the MS for more than the predetermined time, the MS may be determined to have a very high stability. The predetermined time may be set by the manufacturer of the mobile terminal or the mobile communication service provider.

Hereinafter, in the present specification, a case in which the movement of the MS is low is used to mean high stability, and a case in which the movement of the MS is high will be used as a meaning of low stability.

Generally, the maximum number of A sets specified in the standard is 6, the number of N sets is 40, and the number of C sets is not specified, but about 10 is used. A set and C set require more than a certain level of search rate to optimize communication performance and to prevent call drop when MS moves.

As described above, adjusting the number of sets to be searched according to the stability measured by the MS among the embodiments of changing the search mode according to the present invention. Adjusting the will be described as a second embodiment.

Then, with reference to the accompanying drawings will be described a method for performing set management in the MS according to an embodiment of the present invention.

4 is a flowchart illustrating a set search method in which an MS is aquatic according to an embodiment of the present invention.

In step 400, the MS receives a GPS signal from a GPS satellite, and in step 402, the MS periodically measures a location using the received GPS signal to determine whether the user is currently moving. If the user is moving in step 402, the MS proceeds to step 404 to check whether the set search mode currently set in the MS is a general search mode. That is, as in the prior art, it is checked whether it is a general mode for searching all active sets, candidate sets, and neighbor sets.

If the current search mode is set to the normal search mode in step 404, the MS proceeds to step 405 to search for the set with the normal search mode currently set, and if the currently set search mode is not the general search mode, to step 406 Change the search mode to normal search mode.

In step 402, if it is determined that the user does not move, the MS proceeds to step 408 to measure the time for which the stationary state is maintained. In step 410, the MS checks whether the measured time is greater than the preset time. If large, the MS proceeds to step 412 and checks whether the measurement time is longer than the mode search times classified into three steps according to an embodiment of the present invention. do.

In an embodiment of the present invention, the time that the MS has not moved may be measured, and the search mode may be adjusted according to the measured time. In an embodiment of the present invention, the search mode is classified into a first mode, a second mode, and a third mode, and the criteria of the mode classification are classified based on the time when the MS is not moved, that is, the measured length of time.

If the measurement time is greater than the first mode search time and less than the second mode search time, search in the first mode, if greater than the second mode search time, and less than the third mode search time, go to the second mode. If the search is greater than the third mode search time, the search is performed in the third mode.

For example, assuming that the first mode discovery time is 10 minutes, the second mode discovery time is 30 minutes, and the third mode discovery time is 1 hour, a method of changing the discovery mode by the MS according to an embodiment of the present invention will be described. Is as follows.

If the MS has not moved for more than 1 hour, the search is performed in the third mode; if the MS has not moved for more than 30 minutes, the search is performed in the second mode; if it has not moved for more than 10 minutes, the search is performed in the first mode do.

This determination process is performed in step 412 of FIG.

If the measurement time is greater than the first mode search time and less than the second mode search time in step 412, the process proceeds to step 414 to perform the search in the first mode, and the measurement time is greater than the second mode search time. If it is less than the 3 mode search time, the process proceeds to step 416 and performs the search in the second mode. Finally, if the measurement time is greater than the third mode search time, the process proceeds to step 418 to search for the third mode.

Next, an embodiment in which the MS performs a set search when changing the search mode according to the test result in step 412 will be described with reference to the accompanying drawings. 5 and 6 below will be described on the assumption that the number of sets managed by the MS is three sets, two sets, four sets, and four sets.

First, FIG. 5 illustrates a method of adjusting a range of a set to be searched according to a search mode set by an MS according to a first embodiment of the present invention. In step 412 of FIG. 4, since the MS determines that stability has been increased, the MS reduces the range of a set to be searched. In the present invention, a method of reducing the number of N sets to be searched will be described as an example.

T3 500 represents a search range in which the MS searches for sets in normal mode as described above in FIG. On the other hand, T5 (504) shows the set that the MS searches in the third mode selected in step 418 of FIG. 4 according to an embodiment of the present invention. Therefore, T4 502 represents the number of N sets for which the MS does not search only when searching for the set in the third mode. As shown in FIG. 5, the MS searches only the T5 504 section and immediately searches for the next A set 0 508. Therefore, since the MS reduces the range of sets to be searched, in the first embodiment of the present invention, the period of searching for one set is shortened, so that a receiver of the MS to be described later can perform demodulation through a more accurate path signal. It becomes possible. Similarly, T6 506 indicates sets to search when the measurement result MS performs a search in the first mode in step 412. The T7 510 indicates sets to be searched when the measurement result MS performs the search in the second mode in step 412.

In the first embodiment, all four N sets are not searched when searching in the third mode, two N sets are not searched when searching in the second mode, and three N are searched when searching in the first mode. Although the set has not been searched, the number of N sets to be searched can be adjusted according to the degree of stability.

Then, in order to help the understanding of the present invention, a method of adjusting the set range to be searched according to the first embodiment will be described in another method based on the mobility measured by the actual MS.

If the MS measures the movement of the user based on the received GPS signal in step 412, if the movement distance of the user measured for 10 minutes is less than 1 m, the MS determines that the user is low in mobility and moves to the second mode. Perform a search. If the user's movement distance measured for 1 hour is less than 1m, the user's mobility is determined to be very low and the search is performed in the third mode.

On the other hand, if the user's moving distance measured over 1 minute is 1.7 km or more, the user is moving at a very high speed, so the search mode is changed to the normal mode.

6 illustrates a method for adjusting a discovery period according to a discovery mode set by an MS according to a second embodiment of the present invention.

First, before describing FIG. 6, it will be assumed that a period for searching each set is 50ms (T8) when the MS operates in the normal mode. In the normal mode, the MS searches for A set 0 at the first reference number 600 at intervals of 50 ms, then at the reference number 602, and then at the reference numbers 604 and 606 after the T9 section. .

However, when the MS is determined to have high stability and changes the search mode according to an embodiment of the present invention, the peripheral set is not searched for during the preset search period. In FIG. 6, since the search period of the normal mode is assumed to be 50 ms, if the set search is performed according to the second embodiment, the MS does not perform the search of the peripheral set during the T12. Save resources.

In the second embodiment, as in the first embodiment, the search mode of the MS can be changed, but the peripheral sets are searched by increasing the search period according to the measurement time measured by the MS, that is, lowering the search rate.

Referring to FIG. 6, when the general search mode is assumed to be 50 ms, when the search is performed in the first mode as a result of the determination in step 412, the set search period is set to 100 ms (T10). When the search is performed in the second mode, the set search period is increased to 150 ms (T11). When the search is performed in the third mode, the set search period is increased to 200 ms (T12).

Therefore, when the set search period is increased according to the second embodiment of the present invention, when performing the set search in the first mode, it is possible to save the resources of the MS during the T13 (608) interval, and set search in the second mode. In this case, the MS resource is saved during the T14 (610) section, and when the set search is performed in the third mode, the MS resource can be saved during the T15 (611) section.

On the other hand, if the search rate mentioned in the present invention (Search Rate) is high, the search period (Search Period) will be low, while if the search rate is low, anyone skilled in the art will understand that the search period is long.

In addition, although not described herein, the first embodiment and the second embodiment of the present invention may be performed in parallel, and when performed in parallel, it will be obvious that more MS resources can be saved.

7 is a diagram illustrating a configuration of a pilot channel searcher according to the present invention, which is configured with a controller in which a set management function of the present invention is added to a general pilot channel searcher provided in an MS. The controller provided in the general MS may be performed.

First, the pilot channel signal of the base station received through the antenna 701 and the receiver 703 is separated into an I (In-Phase) component and a Q (Quadrature) component and input to the despreader 705. The PN generator 715 and the PN masking 717 generate PN codes corresponding to the PN offset under the control of the controller 719, and the despreader 705 uses I and Q signal components using the input PN codes. Despread The despread signals are accumulated and calculated sequentially through a coherent accumulator 707 and then passed to the energy calculator 709.

The energy calculator 709 calculates the strength of the pilot channel signal by squaring and adding the accumulated I and Q signal components, and the non-coherent accumulator 711 accumulates the strength of the signal obtained for a predetermined time to calculate an average value. Calculate. The sorter 713 aligns the average energy calculated for each set of PN offsets, and the controller 719 reads these values to acquire the pilot channel's acquisition and finger assignments according to a predetermined routine. (finger assignment) and using the GPS signal received by the GPS receiver 723, which will be described later, to measure whether the current user is moving or not, and based on the result, set maintenance according to an embodiment of the present invention. And so on. That is, adjust the range and search rate of the set to search.

The memory 721 stores the pilot offsets, the search results, the A set list, the C set list, the N set list, and the R set list of each set for pilot search and set management of the controller 719. In FIG. 7, the memory 721 may be included in the controller 719. The controller 719 schedules the operation of the pilot channel searcher according to the movement of the user received from the GPS receiver according to the set management method of the present invention, and then executes a search command at a predetermined search rate and search order for each set. The controller of the MS which performs predetermined software processing according to the search result is shown in one block.

Accordingly, the controller 719 measures whether the user moves based on the GPS signal received from the GPS receiver 723, determines the current stability state, and adjusts the search mode accordingly. When the user's movement is not for a predetermined time, that is, when the stability is high, as shown in FIG. 4, the range or the search rate of the search set is adjusted according to the embodiment of the present invention.

The GPS receiver 723 transmits the GPS signal received from the GPS satellite to the controller 719 through the antenna 701 in order for the controller 719 to change the search mode according to an embodiment of the present invention.

When changing the search mode according to the first embodiment of the present invention, the controller 719 determines the range of the set to be searched according to the measurement time, and changes the search rate according to the second embodiment. Then, the configuration of the controller 719 according to the embodiment of the present invention will be described with reference to FIG. 8.

8 is a block diagram of a controller 719 according to an embodiment of the present invention. The mobility determiner 800 receives a GPS signal from the GPS receiver 723 and periodically measures whether the user moves. The set range determiner 802 is provided in the controller 719 according to the first embodiment of the present invention, and adjusts the range of sets to be searched by the searcher according to the determination result of the mobility determiner 800. The search rate adjuster 804 is provided in the controller 719 according to the second embodiment of the present invention, and adjusts the search rate of the searcher according to the determination result of the mobility determiner 800. The search rate adjuster 804 also sets a set search period to control the timer 806 to count the search period.

8 illustrates the set range determiner 802 according to the first embodiment of the present invention, the search rate adjuster 804 and the timer 806 according to the second embodiment of the present invention, respectively. It may be provided separately.

As described above, according to the present invention, if the stability of the mobile terminal is high in the management of sets for pilot channel discovery in a mobile communication system, reducing the range of a set to be searched shortens the set search period, so that more accurate positions of the sets ( Position) information can be obtained.

In addition, by fixing the search period and reducing the number of sets, it is possible to save the resource of the mobile terminal by reducing the number of searches compared to a predetermined time. On the contrary, when the stability of the mobile terminal is low, the mobile terminal is controlled to operate in the normal mode so that the call quality can be maintained even when moving at a high speed by relatively widening the range for the mobile terminal to search for the set.

Claims (8)

In the set management method in a mobile terminal of a mobile communication system, Periodically receiving a Global Positioning System (GPS) signal and determining whether the mobile terminal moves based on the received GPS signal; If the mobile terminal has not moved, the set management method of the mobile communication system, characterized in that it comprises the step of adjusting the set search range. According to claim 1, The adjusting of the set search range may include adjusting a search range of a neighbor set. According to claim 1, If the mobile terminal has not moved, the set management method of the mobile terminal in the mobile communication system, characterized in that it further comprises the step of adjusting the set period. The method of claim 3, wherein The adjusting of the set search period reduces the search rate by reducing the number of neighboring sets to be searched. A pilot channel searcher of a mobile terminal for receiving pilot channel signals from a plurality of base stations of a mobile communication system and performing set management for a set of pilot offsets of each base station, A despreader for despreading the I and Q components of the pilot channel signal received through the antenna from the base station using predetermined PN codes; A PN generator for generating the PN codes according to a predetermined control signal; The despread signals are accumulated with a coherent accumulator, An energy calculator for calculating energy values of the accumulated signals; A non-coherent accumulator for accumulating the energy value calculated for a predetermined time and calculating an average energy value; A sorter for aligning the average energy values for the pilot offsets; And a controller for periodically receiving a GPS (Global Positioning System) signal to check whether the mobile terminal is moved and, if the mobile terminal is moved, to adjust a set search range. The method of claim 5, And the controller controls the search range by adjusting the search range of a neighboring set. The method of claim 5, And the controller is further configured to adjust a set search period when the mobile terminal moves. The method of claim 7, wherein Wherein the controller adjusts the set search period by reducing the search rate by reducing the number of neighbor sets to search.

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