JP4675199B2 - Mobile phone, cell search method and cell search program - Google Patents

Description

  The present invention relates to a cell search method in a mobile phone.

  Conventionally, a mobile phone is given several scrambling codes for frequencies at which communication is performed from a base station that has registered its location. The scrambling code is a code for the mobile phone to recognize the base station, and one scrambling code corresponds to one base station. A signal from the corresponding base station can be specified using the scrambling code, and the reception level of the signal can be obtained. By acquiring a plurality of scrambling codes from the base station where the location is registered, it becomes possible to search for a base station that is likely to be able to communicate next easily when the mobile phone moves. Some scrambling codes given from the base station include a scrambling code corresponding to the base station and a scrambling code corresponding to the surrounding base stations.

  The mobile phone compares the reception level of the signal from the corresponding base station with the threshold value (hereinafter referred to as “Sintrasearch”) to ensure stable communication broadcast from the base station for those scrambling codes. It is carried out. And when the reception level is lower than Sintrasearch, not only the given scrambling code but all the scrambling codes have the reception level that does not satisfy Sintrasearch, or the one that satisfies it, the most. Cell reselection is performed by detecting which scrambling code corresponds to a signal having a high reception level from the base station. Cell reselection means resetting which base station the own device communicates with, that is, updating location registration to the base station. All the scrambling codes are detected at a rate of about once every 10 seconds.

A mobile phone searches for a new base station in good communication state in order to perform more stable communication. Patent Document 1 discloses a mobile phone that performs the search at high speed.
JP 2002-158614 A

By the way, the conventional search method has a problem that power consumption is unnecessarily high. Basically, in mobile phones, the battery life is getting better due to technological advances, but it goes without saying that we want to keep power consumption as low as possible in the waiting state.
Therefore, an object of the present invention is to provide a mobile phone capable of searching for a base station for performing stable communication while suppressing power consumption.

  In order to solve the above problems, a mobile phone according to the present invention includes a first threshold for comparison with a reception level, a second threshold corresponding to a reception level lower than the first threshold, and a plurality of base stations. Storage means for storing base station information for selectively receiving signals from each of the stations, receiving means for receiving signals from the base station, and each of the plurality of base stations based on the base station information. Detecting means for detecting a receiving level of each signal received by the receiving means; and receiving levels of all signals from the plurality of base stations detected by the detecting means are less than or equal to the first threshold and at least one When the signal reception level is higher than the second threshold, a cell search is performed at a first time interval, and the reception levels of all signals from the plurality of base stations are equal to or lower than the second threshold. If yes It is characterized in that it comprises a and a search unit performing cell search in a short second time interval than the first time interval.

  In this case, in principle, the cell search detects the reception level of signals from all base stations at the frequency at which the mobile phone registers the location with the base station and performs communication, and communication is stabilized. Determining whether there is something that meets the threshold. The principle is that, for example, if there is a reception level that satisfies the threshold, it may be possible to stop the search.

  With the above-described configuration, the mobile phone is in a waiting state, and conventionally, at a second time interval, for example, 4DRX (Discontinuous Reception) interval (for example, 1DRX = 2.56 seconds) below the first threshold. In the present invention, when there is a reception level between the first and second thresholds, the cell search is executed at a first time interval, for example, at a 12DRX interval.

By doing so, it is possible to suppress the execution of the cell search in the waiting state as much as possible, thereby obtaining the effect of leading to power saving.
Further, the mobile phone further includes an acquisition unit that acquires the first threshold value from a base station and stores the first threshold value in the storage unit, and the second threshold value is stored in the storage unit in advance. Good.

As a result, the first threshold value is reported from the base station as usual, but the second threshold value is stored in advance in the mobile phone and the cell search time interval can be determined. The optimal second threshold value can be stored in advance by experimentally investigating a threshold value in which a power saving effect is obtained and communication is not interrupted as much as possible.
Further, the base station information stores information on a plurality of base stations having a high possibility of communication at each frequency corresponding to each of the plurality of frequencies, and the detecting means is configured to detect from the plurality of base stations at each frequency. When the reception level of the signals from the plurality of base stations is lower than the second threshold value for all frequencies among the plurality of frequencies. The cell search may be executed at the second time interval.

As a result, the cell search is executed at the second time interval only when the reception levels of the signals from the plurality of base stations fall below the second threshold at all the plurality of frequencies. The timing at which the search is executed is further delayed, and further power saving effect can be expected.
The base station information may store information on a plurality of base stations corresponding to each of a plurality of frequencies, and the search means may execute a cell search for all the plurality of frequencies.

Thereby, although the effect of power saving is reduced, the cell search is executed for all of a plurality of frequencies, so that the reliability of communication can be increased.
Further, the storage means further stores a third threshold value corresponding to a reception level lower than the second threshold value, and the search means further determines that the reception levels of all signals are the third threshold value. In the case of less than, cell search may be executed at a third time interval that is shorter than the second time interval.

As a result, it is possible to set a threshold value in a stepwise manner and set the timing for executing the cell search more finely, and to achieve both power saving and ensuring communication more finely.
A cell search method for performing cell search in a mobile phone, the first threshold for comparing with a reception level, and a second threshold corresponding to a reception level lower than the first threshold; Storing a base station information for selectively receiving a signal from each of the plurality of base stations, a receiving step for receiving a signal from the base station, and the plurality of base stations based on the base station information A detection step of detecting a reception level of each signal received from each of the stations in the reception step, and reception levels of all signals from the plurality of base stations detected in the detection step are equal to or less than the first threshold value; When the reception level of at least one signal is higher than the second threshold, a cell search is performed at a first time interval, and all signals are received from the plurality of base stations. When the bell is below the second threshold value may as possible and a search step of performing cell search in a short second time interval than the first time interval.

  Alternatively, a cell search program showing a processing procedure for determining a timing for causing a cell phone computer having a memory to execute a cell search, wherein the memory includes a first threshold value for comparison with a reception level, and A second threshold corresponding to a reception level lower than the first threshold and base station information for selectively receiving signals from each of the plurality of base stations are stored, and the processing procedure is performed from the base station A reception step of receiving a signal of the first signal, a detection step of detecting a reception level of each signal received in the reception step from each of the plurality of base stations based on the base station information, and a plurality of the plurality of detected in the detection step When the reception level of all signals from the base station is less than or equal to the first threshold and the reception level of at least one signal is above the second threshold The cell search is performed at the first time interval, and when the reception levels of all signals from the plurality of base stations are equal to or lower than the second threshold, the cell search is shorter than the first time interval. And a search step for performing a cell search at a second time interval.

  With these methods and programs, the mobile phone can determine the timing for executing the cell search.

Hereinafter, a mobile phone according to the present invention will be described with reference to the drawings.
<Embodiment>
<Overview>
The outline of the present invention will be described using FIG. 1 while comparing with the conventional case. FIG. 1A shows the conventional case, and FIG. 1B shows the case of the present application. 1 (a) and 1 (b) both show the correspondence between the reception level Squal and the threshold value in the vertical direction, and it is assumed that the reception level is higher on each drawing.

  Conventionally, when the mobile phone is waiting, the reception level Squal of the communication frequency with the base station with which the mobile device is registered becomes equal to or lower than the Sintrasearch (for example, 10 dB) notified from the base station. Then, a cell search is performed every 4DRX. As described above, the cell search here refers to confirming the reception level of signals from the base station corresponding to all scrambling codes of the communication frequency, and is hereinafter referred to as a full search. In the full search, for example, scrambling code values are added one by one in order from 1 and the received signal and Sintrasearch are compared for each scrambling code. Full search can be executed in tens of milliseconds. In a normal state, the mobile phone checks the reception level only for the signal from the base station corresponding to the scrambling code written in the cell search list acquired from the base station, and hereinafter this is expressed as list search.

  In this application, when the mobile phone is waiting and the reception level Squal of each of the signals from the plurality of base stations in the cell search list at the communication frequency of its own device falls below the specified value Sintrasearch broadcast from the base station It is further determined whether or not it is lower than a predetermined threshold Y. If it is higher than the threshold Y, a full search is performed at a time interval 12DRX longer than the conventional one. When the reception level falls below the threshold Y, a full search is performed at the same time interval 4DRX as before. Further, a threshold W lower than the threshold Y is provided, and when the reception level is lower than the threshold W, a full search is performed for each DRX to detect a scrambling code having a stable communication frequency.

The Squal is obtained by subtracting the minimum quality level of Ec / Io from the Ec / Io measurement value of CPICH (Common Pilot Channel). Ec is CPICH received power, and Io is the sum of interference power and thermal noise power. The Ec / Io measurement value is measured based on a conventional method. The minimum quality level of Ec / Io is a value broadcast from the base station and is usually −20 dB. Sintrasearch is 10 dB. These values are determined based on actual measurement values of Ec / Io measurement values.
<Configuration>
Next, the functional configuration of the mobile phone will be described with reference to the block diagram of FIG.

FIG. 2 is a block diagram showing a functional configuration of the mobile phone 200 according to the present invention. As shown in FIG. 2, the mobile phone 200 includes a communication unit 210, a determination unit 220, a voice processing unit 230, an operation unit 240, a display unit 250, a storage unit 260, a time measuring unit 270, and a control unit 280. It is comprised including.
The communication unit 210 includes an antenna 211, demodulates the received signal received from the antenna 211 into a received voice signal and a received data signal, the demodulated received voice signal to the voice processing unit 230, and the received data signal to the control unit. 280 to output to 280. Further, it has a function of modulating a transmission voice signal A / D converted by the voice processing unit 230 and a transmission data signal such as an electronic mail given from the control unit 280 and outputting the modulated data signal from the antenna 211.

In the present application, in particular, the determination unit 220 has a function of notifying the determination unit 220 of a reception level of a frequency for communicating with a base station whose location is registered, and the base station also receives a Sintrasearch and a cell search table 261. And the like. Sintrasearch and cell search table 261 will be described later.
The determination unit 220 compares the reception level of the frequency updated by the communication unit 210 with the Sintrasearch stored in the storage unit 260, the threshold value Y, and the threshold value W, and the comparison result is sent to the control unit 280. It has a function to notify.

The voice processing unit 230 performs D / A conversion on the reception voice signal output from the communication unit 210 and outputs it to the speaker 232, and A / D converts the transmission voice signal acquired from the microphone 231, and outputs the generated signal. It has a function of outputting to the communication unit 210.
The operation unit 240 includes a group of keys such as a numeric keypad, an on-hook key, an off-hook key, a direction key, and an enter key, and has a function of receiving a user operation and transmitting the received operation content to the control unit 190.

The display unit 250 is a monitor realized by an LCD (Liquid Crystal Display) or the like, and has a function of displaying an image in accordance with an instruction from the control unit 280, and displays a standby screen, a mail document, and the like.
The storage unit 260 includes a ROM (Read Only Memory) and a RAM (Random Access Memory), and is realized by a small hard disk, a nonvolatile memory, or the like. Has a function of storing. In particular, the cell search table 261 is stored in the present application. In addition, Sintrasearch, which is a threshold value of a full search to be executed while waiting, a threshold value Y, and a threshold value W are stored. Sintrasearch is notified from the base station and becomes a threshold value of the frequency with which the device is communicating. Originally, Sintrasearch is a reception level threshold for guaranteeing stable communication. Both the threshold value Y and the threshold value W are set by the manufacturer of the mobile phone 200 at the design stage. The threshold Y is set lower than Sintrasearch, and the threshold W is set lower than the threshold Y. Here, the threshold Y is set to 4 dB, and the threshold W is set to 0 dB.

The timekeeping unit 270 measures time and has a function as a timer. Based on the time interval instruction of the control unit 280, the control unit 280 is notified of the time elapse of 4DRX and the time elapse of 12DRX.
The control unit 280 has a function of controlling each unit of the mobile phone 200, and in particular, determines a time interval for executing a full search according to a comparison result between the reception level notified from the determination unit 220 and each threshold value. Specifically, when the reception level is Sintrasearch or lower and above Y, it is determined that the time sensation for executing the full search is 12DRX. When the reception level is higher than W and equal to or lower than Y, the time interval for executing the full search is set to 4DRX as usual. When the reception level is W or less, the DRX full search is set to be executed every time.
<Data>
FIG. 3 shows an example of a cell search table that the mobile phone 200 receives from the base station.

The cell search table 261 stores a frequency 301, a PSC (Prior Scrambling Code) 302, and an SC (Scrambling Code) 303.
In the frequency 301, the leftmost frequency indicates the frequency at which the own device registers the current position and communicates. In the figure, it is 10712 Hz. The other frequencies indicate other frequencies that can be communicated, and the priority decreases as it goes to the right. In the cell search table 261, 10688 Hz and 10737 Hz are stored as other frequencies.

The PSC 302 indicates a scrambling code that seems to be optimal and communicable at each frequency. For example, PSC is 1 when the frequency is 10712 Hz.
SC303 indicates a scrambling code that can be communicated at each frequency. For example, in the case of a frequency of 10712 Hz, they are 3, 6, 28, and 101 in order from the top.

Each scrambling code corresponds to one base station, ie, one cell.
Basically, PSC and SC are assumed to be 20 or less in total for each frequency.
<Operation>
FIG. 4 shows a timing chart of the timing for executing list search and full search in the mobile phone 200.

  FIG. 4A is a diagram illustrating timings for determining whether or not the reception level satisfies Sintrasearch for each frequency and each scrambling code in the cell search table 261. That is, the list search is performed at the timing shown in FIG. That is, a search is performed for the scrambling code written in the cell search table at a rate of once per 1DRX. 1DRX is set to 2.56 seconds.

  FIG. 4B shows the timing for executing the full search when the reception level Squal is higher than the threshold Y and equal to or less than Sintrasearch. For example, in the list search at time T1 in FIG. 4A, when the reception level satisfies this condition, the full search is set to be executed at time T16 correspondingly. As long as the reception level satisfies this condition, a full search is executed every 12 DRX. In this case, it is at T17 that the full search is executed next to time T16.

  FIG. 4C shows the timing at which a full search is executed when the reception level Squal is higher than the threshold value W and lower than or equal to the threshold value Y. For example, in the list search at time T1 in FIG. 4A, when the reception level satisfies this condition, the full search is set to be executed at time T18 correspondingly. Thereafter, if the reception level is maintained within the same range, a full search is executed at times T19, T20, and T21.

  FIG. 4D shows the timing for executing a full search when the reception level Squal is equal to or less than the threshold value W. For example, in the list search at time T1 in FIG. 4A, when the reception level satisfies this condition, the full search is set to be executed at the next time T22. If the same reception level is maintained thereafter, a full search is also performed at times T23, T24,.

Next, the operation of the present embodiment will be described with reference to the flowchart shown in FIG.
The determination unit 220 of the mobile phone 200 determines whether the reception level of signals from a plurality of base stations in the cell search table is lower than the Sintrasearch for the communication frequency for which the own device registers the location for each 1DRX. (Step S501).
If Squal is not less than or equal to Sintrasearch (NO in step S501), if full search is set, the setting is canceled and list search is continuously executed. If Squal is equal to or less than Sintrasearch (YES in step S501), it is next determined whether Squal is equal to or less than threshold Y (step S503).

If Squal is not less than or equal to the threshold Y (NO in step S503), a full search is executed and a setting is made so that a full search is executed every 12 DRX (step S511). Then, the process returns to step S501 and the subsequent processing is executed.
If Squal is less than or equal to threshold Y (YES in step S503), it is next determined whether or not Squal is less than or equal to threshold W (step S505). If Squal is not less than or equal to the threshold value W (NO in step S505), the full search is executed and the full search is set to be executed every 4DRX, and the process returns to step S501 to execute the subsequent processing. . If Squal is less than or equal to the threshold value W (YES in step S505), the full search is executed and the full search is set to be executed every 1 DRX, and the process returns to step S501 to execute the subsequent processing. .

In steps S507, S509, and S511 of the above operation, if the same setting has been made so far, the setting is not updated and the full search is not executed if it is not the full search execution timing.
The mobile phone 200 repeats the above process while waiting.
<Supplement>
Although the mobile phone according to the present invention has been described according to the above embodiment, the embodiment of the present invention is not limited to this. Hereinafter, the modified example will be described.
(1) In the above embodiment, Y and W are provided as threshold values under Sintrasearch. However, these are not necessarily two, and for example, only Y or three or more may be provided. Good. In the present invention, there should be at least two threshold values.

In addition, the numerical value of each threshold value in the above is not necessarily the value, and may be another numerical value.
(2) In the above embodiment, for the sake of brevity, the full search is executed every 4DRX when the Squal of the frequency registered by the own device is equal to or less than the threshold value Y. The full search may be executed every 4 DRXs only when the reception level of the signal from the base station corresponding to all the scrambling codes of all the frequencies shown in Table 261 is equal to or lower than the threshold Y.

There seems to be a high possibility that a sufficient reception level can be secured for a frequency that is considered to be easy to communicate in the cell search table 261 other than the frequency for which the own device is registered. If the threshold Y is set for other frequencies and the full search is executed when the threshold Y is below the threshold Y, the conditions for executing the full search become stricter. As a result, further power saving can be achieved.
(3) In the above embodiment, the full search is executed only for the frequency for which the own device is registered. However, in order to ensure more stable communication, the full search is performed for all frequencies in the cell search table. A search may be executed. However, in this case, the power saving effect is diminished.
(4) In the above embodiment, the execution timing of the full search at the frequency for which the own device is registered is described. However, the timing at which the full search is similarly executed for each of the other frequencies in the cell search table. May be defined as in the present invention.
(5) In the above embodiment, when there is a variation of Squal and the threshold is crossed, the full search is immediately executed and the execution timing is set. However, when it continuously changes across one threshold, a full search is continuously executed. For example, after the timing for executing a full search is set to 12DRX once, when the next DRX, the Squal is below the threshold Y, and then the Squal exceeds the threshold Y and is equal to or less than the Sintrasearch, The full search is executed three times in succession. In this case, since the frequency of full search is increased, the power saving effect is diminished.

Therefore, information on the past history, that is, the timing at which the previous full search has been set and the time when the full search was last executed is left in the storage unit 260, and the full search is performed by referring to the information. You may make it judge whether it performs.
That is, a specific example will be described with reference to the timing chart of FIG. 4. First, assuming that the reception level Squal satisfies Y <Squal ≦ Sintrasearch at time T1, a full search is executed at time T16 correspondingly. And Then, at time T2, the reception level decreases, and a full search is executed correspondingly. When the reception level Squal satisfies Y <Squal ≦ Sintrasearch again at time T3, the previous full search has been set to 12DRX, and the last full search was actually executed at T16. If the reception level does not change with reference to the information and the full search is originally performed at 12DRX, it is determined that the next execution is scheduled to be performed at time T17, and the full search is performed in a form corresponding to the change at time T3. A full search may be executed at time T17 without executing it.
(6) In the embodiment described above, the setting such as the set threshold value or less may be arbitrarily set by the designer of the mobile phone, and the threshold value or less may be set to less than the threshold value. That is, the threshold may be any material that can be used to determine which range the reception level is in.
(7) The present invention may be the method described above. Further, the present invention may be a computer program that realizes these methods by a computer, or may be a digital signal composed of the computer program.

Further, the present invention may be the one in which the computer program or the digital signal is recorded on a computer-readable recording medium such as a hard disk or a semiconductor memory. Further, the present invention may be the computer program or the digital signal recorded on these recording media.
In the present invention, the computer program or the digital signal may be transmitted via an electric communication line, a wireless or wired communication line, a network represented by the Internet, or the like.

  The mobile phone according to the present invention can be used as a mobile phone with low power consumption in a waiting state.

It is the schematic which showed the outline | summary of this invention and the comparison of a prior art. It is the block diagram which showed the function structure of the mobile telephone which concerns on this invention. An example of a cell search table received by a mobile phone from a base station is shown. It is a timing chart which showed the timing which a mobile telephone searches. It is the flowchart which showed the operation | movement regarding the setting of the search of a mobile telephone.

Explanation of symbols

200 Cellular Phone 210 Communication Unit 211 Antenna 220 Determination Unit 230 Audio Processing Unit 231 Microphone 232 Speaker 240 Operation Unit 250 Display Unit 260 Storage Unit 261 Cell Search Table 270 Timekeeping Unit 280 Control Unit

Claims (8)

A first threshold for comparing with a reception level, a second threshold corresponding to a reception level lower than the first threshold, and a base station for selectively receiving signals from each of a plurality of base stations Storage means for storing information;
Receiving means for receiving a signal from the base station;
Detecting means for detecting a reception level of each signal received by the receiving means from each of the plurality of base stations based on the base station information;
When the reception level of all signals from the plurality of base stations detected by the detection means is equal to or lower than the first threshold and the reception level of at least one signal is higher than the second threshold When the cell search is performed at the first time interval and the reception levels of all signals from the plurality of base stations are equal to or lower than the second threshold, the second time shorter than the first time interval a search unit performing cell search at the time intervals,
Obtaining means for obtaining the first threshold value from a base station and storing it in the storage means;
The mobile phone, wherein the second threshold value is stored in advance in the storage means .   The mobile phone further includes search storage means for storing information on the cell search performed by the search means,
  The search means includes
  Controls the execution of the cell search based on the information stored in the search storage means that executed the cell search.
  The cellular phone according to claim 1. In the base station information, information on a plurality of base stations having a high possibility of communication at each frequency corresponding to each of a plurality of frequencies is stored,
The detecting means detects a reception level of a signal from the plurality of base stations of each frequency;
The search means performs a cell search at the second time interval when reception levels of signals from the plurality of base stations for all frequencies out of the plurality of frequencies fall below the second threshold. The mobile phone according to claim 1, wherein: In the base station information, information of a plurality of base stations is stored corresponding to each of a plurality of frequencies,
The mobile phone according to claim 1, wherein the search means executes a cell search for all of the plurality of frequencies. The storage means further includes
Storing a third threshold corresponding to a reception level lower than the second threshold;
The search means further includes:
The cell search according to claim 1, wherein when the reception level of all signals is lower than the third threshold, the cell search is executed at a third time interval shorter than the second time interval. Phone. The search storage means includes
  Executed when reception levels of all signals from the plurality of base stations detected by the detection means are equal to or lower than the first threshold and at least one reception level is higher than the second threshold. Information on the execution of the first cell search is stored,
  Execution of a second cell search based on information obtained by executing the first cell search stored in the search storage means by the search means,
  After the execution of the first cell search, a cell search is executed within the first time interval from the execution of the first cell search, and all of the plurality of base stations detected by the detection means are detected. Cell search when the reception level of the signal is lower than the first threshold and at least one reception level is higher than the second threshold. Is controlled to perform the second cell search at the first time interval from the execution of the first cell search.
  The mobile phone according to claim 2. A cell search method for performing cell search in a mobile phone,
A first threshold for comparing with a reception level, a second threshold corresponding to a reception level lower than the first threshold, and a base station for selectively receiving signals from each of a plurality of base stations A storage step for storing information;
A receiving step for receiving a signal from the base station;
A detection step of detecting a reception level of each signal received in the reception step from each of the plurality of base stations based on the base station information;
When the reception level of all signals from the plurality of base stations detected in the detection step is equal to or lower than the first threshold and the reception level of at least one signal is higher than the second threshold When the cell search is performed at the first time interval and the reception levels of all signals from the plurality of base stations are equal to or lower than the second threshold, the second time shorter than the first time interval A search step for performing a cell search at a time interval of :
Obtaining the first threshold from a base station and storing it in the storage means of the mobile phone,
The cell search method, wherein the second threshold value is stored in advance in the storage means . A cell search program showing a processing procedure for determining a timing for causing a cell phone computer having a memory to execute a cell search,
The memory selectively receives a first threshold for comparison with a reception level, a second threshold corresponding to a reception level lower than the first threshold, and a signal from each of a plurality of base stations. Base station information to be stored,
The processing procedure is as follows:
A receiving step for receiving a signal from the base station;
A detection step of detecting a reception level of each signal received in the reception step from each of the plurality of base stations based on the base station information;
When the reception level of all signals from the plurality of base stations detected in the detection step is equal to or lower than the first threshold and the reception level of at least one signal is higher than the second threshold When the cell search is performed at the first time interval and the reception levels of all signals from the plurality of base stations are equal to or lower than the second threshold, the second time shorter than the first time interval A search step for performing a cell search at a time interval of :
Obtaining the first threshold from a base station and storing it in a memory of the mobile phone,
The cell search program, wherein the second threshold value is stored in the memory in advance .

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