JP2008066892A - Mobile wireless terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mobile wireless terminal capable of saving electric power while taking the moving speed of the mobile wireless terminal into consideration in a system like a wireless LAN. <P>SOLUTION: AP scan processing is performed (S2) under AP scan control (S1) actuated by a changeable timer. When no desired AP is detected (NO at S3), AP scan result analysis processing is performed (S6). In the internal processing of S6, a positive value TL is set to ΔT when the mobile wireless terminal is outside an AP zone, when a last PA and a current AP are different (namely, in high-speed movement), or when variation in reception signal intensity from a last scan to a current scan is larger than a prescribed specified value although the APs are the same (in the high-speed movement). A negative value "-TS" is set to ΔT when the APs are the same and the variation in reception signal intensity from the last scan to the current scan is smaller than the prescribed specified value (in low-speed movement). Accordingly, a scan period becomes long or short (S7). This scan period is set to the timer (S9). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a portable wireless terminal capable of reducing power consumption during standby of a wireless LAN.

  In a small cell type mobile terminal device, if it moves at a high speed, the time spent in one zone (cell) is shortened, and although it is not suitable for communication, it consumes current wastefully. There is a mobile terminal device of a mobile communication system that has taken such measures (see, for example, Patent Document 1). The zone configuration of this mobile communication system is arranged such that a plurality of zones partially overlap.

When the mobile terminal apparatus detects that the received signal from the base station has dropped to a reception electric field level that is not suitable for standby, it recognizes zone movement, and then performs a zone search for a reception electric field level that can be standby. This recognizes movement between zones. When the number of movements between zones per unit time exceeds the allowable number of movements, it is determined that the movement is not suitable for communication, and control is performed to turn off the power of the terminal device or the wireless unit for a certain period of time.
Japanese Patent Laid-Open No. 9-84093 (pages 2 and 3, FIGS. 2 and 3)

  In a system where access points are scattered far apart like a wireless LAN although it is a small cell system, when the background technology (Patent Document 1) is applied, the power of the wireless unit passes between the access points for a certain period of time. It stands up quickly and does not provide effective power saving. In addition, there is a high probability of being out of service and there may be no access point used for determination.

  An object of the present invention is to provide a portable wireless terminal capable of saving power in consideration of the moving speed of the portable wireless terminal even in a system such as a wireless LAN.

  In order to achieve the above object, a portable wireless terminal of the present invention receives a signal from a wireless LAN communication access point by periodically starting the timer and the timer, and measuring the received signal quality and the access point. Scan processing means for performing identification, and a scan result that is periodically activated by the timer and sets the period of the timer to be longer when the fluctuation amount of the received signal quality per predetermined period is greater than a predetermined value And an analysis processing means.

  According to the present invention, even in a system such as a wireless LAN, power saving considering the moving speed of a portable wireless terminal and early detection of a wireless LAN cell during low-speed movement suitable for the wireless LAN can be performed.

  FIG. 1 is a diagram for explaining the movement of a wireless LAN access point and a portable wireless terminal according to an embodiment of the present invention. AP0, AP1, AP2, AP3, and APX are access points, and a circle represents a cell that is the effective range of the access point. The effective range of the access point is about 100 m, and since it is scattered, the area outside the access point range is wide.

  Symbols t0 to t10 represent a fixed cycle timing, and a solid line connecting the symbols indicates a movement trajectory of the mobile wireless terminal. Accordingly, when the timing interval is wide, the mobile wireless terminal moves fast, and when the interval is narrow, the mobile wireless terminal moves slowly.

  FIG. 2 is a block diagram of relevant portions of the portable wireless terminal according to the embodiment of the present invention. The portable wireless terminal 100 includes a main control unit 1, a timer 2, a wireless LAN antenna 3, a wireless LAN control unit 4, and the like. Further, the wireless LAN control unit 4 includes a wireless LAN communication unit 5, various setting control units 6, an access point scan control unit 7, a current scan result information memory 8, a previous scan result information memory 9, an authentication control unit 10, and a connection communication control. Unit 11, cutting control unit 12, and the like.

  The main control unit 1 controls the entire mobile radio terminal 100. The timer 2 is for periodically starting the wireless LAN control unit 4, and the cycle is variable by the wireless LAN control unit 4 itself. The wireless LAN antenna 3 transmits and receives radio waves to and from the wireless LAN access point. The wireless LAN control unit 4 is periodically activated by the timer 2 and enters a wake-up state to perform overall control of wireless LAN communication.

  Specifically, the wireless LAN communication unit 5 of the wireless LAN control unit 4 performs modulation / demodulation processing of wireless LAN communication. The various setting control units 6 manage wireless LAN access point information. The access point scan control unit 7 sets the period of the timer 2 and the like by access point scan processing and scan result analysis.

  The current scan result information memory 8 stores SSIDs (service set identifiers) that are ID information of a plurality of access points scanned at the current timing and the received signal strengths thereof. The previous scan result information memory 9 stores the SSID and the received signal strength of the access point having the strongest received signal strength among the access points scanned at the previous timing.

  The authentication control unit 10 authenticates the access point detected by the access point scan control unit 7. The connection communication control unit 11 performs connection with an access point, data communication processing, and the like after authentication by the authentication control unit 10. The disconnect control unit 12 performs disconnect processing with the access point after the end of data communication.

FIG. 3 is an operation flowchart of the access point scan control unit of the portable wireless terminal according to the embodiment of the present invention.
FIG. 4 is an operation flowchart of the AP scan result analysis process in the access point scan control unit of the portable wireless terminal according to the embodiment of the present invention, which is a part of the process of FIG.
This will be described below with reference to both figures. The access point scan control (step S1) is started by the timer 2. In the access point scan control process, the period of the timer 2, that is, the scan period is variably controlled by itself according to the moving speed of the mobile wireless terminal and the AP detection result, and unnecessary power is reduced to save power. The purpose is.

  First, when access point scan control (step S1) is started by a timer, AP scan processing is executed (step S2). The AP scan process has the following two methods, and any method may be used. One is a method using passive scanning, in which a portable wireless terminal waits for and receives a beacon from an access point. And if a beacon is received, SSID (service set identifier) which is ID information of an access point is read. Also, the received signal strength of the beacon measured by the wireless LAN communication unit is referred to.

The other is a method based on active scan, in which the portable wireless terminal sends a probe request without AP designation to the access point. All access points that have received this send out a probe response. When the portable wireless terminal can receive the probe response, it reads the SSID that is the ID information of the access point. Further, the received signal strength measured by the wireless LAN communication unit is referred to. In any case, reading of signals such as SSID can be performed only within the effective range of the access point.
The plurality of SSIDs and received signal strengths read as described above are stored in the current scan result information memory 8.

  Next, if the SSID can be detected, it is checked whether there is a desired AP (step S3). The desired AP is an AP set by the user in advance in the portable wireless terminal for wireless LAN communication purposes. If the desired AP is detected (YES in step S3), the process as the access point scan control unit ends, and the authentication control unit is entered (step S4).

  After step S4, that is, only in the case of the desired AP, the process proceeds to the processing of the authentication control unit 10, the connection communication control unit 11, and the disconnection control unit 12, but the operation flowchart is omitted. The authentication control unit 10 authenticates the desired access point detected by the access point scan control unit 7. The connection communication control unit 11 performs connection with an access point, data communication processing, and the like after authentication by the authentication control unit 10. The disconnect control unit 12 performs disconnect processing with the access point after the end of data communication.

  In the case of NO in step S3, this includes the case where another AP that is not the desired AP is detected and the case where it is out of the AP range. In this case, as described below, the access point scan control operation is continuously repeated, and the scan cycle is variably controlled. Specifically, first, it is checked whether it is the scan result analysis execution timing (step S5). This scan result analysis execution timing is a fixed period longer than the variable period of the access point scan control (step S1). Since the access point scan control (step S1) is a variable cycle, this variable cycle (scan cycle of step S9 described later) is added every time to detect that the scan result analysis execution timing has become a fixed cycle. Alternatively, another dedicated constant timer may be provided.

  The reason why the scan result analysis execution timing period is set to a constant period is that the AP scan result analysis process (step S6) to be performed next detects the moving speed of the portable wireless terminal. The reason why the scan result analysis execution timing period is made slower than the access point scan control timing period is that the AP scan result analysis process (step S6) to be performed is reflected in the variable period of access point scan control. Because you don't have to do that often.

Details of the AP scan result analysis process (step S6) will be described next.
In FIG. 4, first, the current scan result information memory 8 which is the result of the AP scan process (step S2 in FIG. 3) is read (step S61). Here, when there is no SSID, that is, when no AP is detected (“None” in step S62), it is out of service area, and a positive value TL is set as ΔT that increases or decreases the scan period by unit time (step S65). As this value will be described later (step S7 in FIG. 3), every time the access point scan control is executed, a positive value TL is added to the current scan cycle, the scan cycle becomes longer, and power is saved.

  If an AP is detected in step S62, it is checked whether the AP having the strongest received signal strength and the AP (registered AP) having the strongest received signal strength at the previous scan stored in the previous scan result information memory 9 are the same. (Step S63). If they are different, it is determined that the target AP has changed, that is, the mobile wireless terminal is moving at high speed. Also in this case, a positive value TL is set as ΔT that increases / decreases the scan cycle by unit time as in the case of out of service area (“none” in step S62) (step S65). Also in this case, as will be described later (step S7 in FIG. 3), every time the access point scan control is executed, a positive value TL is added to the current scan cycle, the scan cycle becomes longer, and power is saved. become.

  In step S63, if the AP with the strongest received signal strength and the registered AP at the previous scan are the same, the portable wireless terminal exists in the same AP. In that case, next, in order to detect the moving speed, the fluctuation amount of the received signal strength at the previous scan and the received signal strength at the current scan of the same AP is calculated and compared with a predetermined specified value (step) S64). If the fluctuation is greater than the specified value, it is determined that the mobile wireless terminal is moving at high speed, and a positive value TL is set as ΔT that increases or decreases the scan period by unit time (step S65). Also in this case, as will be described later (step S7 in FIG. 3), every time the access point scan control is executed, a positive value TL is added to the current scan cycle, the scan cycle becomes longer, and power is saved. become.

  In step S64, when the fluctuation is smaller than the specified value, it is assumed that the portable wireless terminal is moving at low speed or is stopped, and is determined to be suitable for wireless LAN communication, and ΔT that increases / decreases the scan cycle by unit time The negative value “−TS” is set (step S66). As this value will be described later (step S7 in FIG. 3), every time the access point scan control is executed, a negative value “−TS” is added to the current scan cycle, the scan cycle is shortened, and the AP is captured. It becomes easy.

  Following step S65 and step S66, the SSID and the received signal strength of the AP having the strongest received signal strength in the current scan result information memory 8 are stored in the previous scan result information memory 9 (step S67). This is for the next scan result analysis process. Then, the current scan result analysis process is terminated, and the process returns (step S68).

  Next, returning to the processing of FIG. 3, after step S6, every time the access point scan control is executed, the positive value TL or negative value which is ΔT described above (steps S65 and S66 of FIG. 4) in the current scan cycle. The value “−TS” is added (step S7). Depending on each, the scan period is longer or shorter. An upper limit and a lower limit are set in the scan cycle, and clamping is performed so as not to exceed the values (step S8). Then, this scan cycle is set in the timer 2 (step S9), and the process ends (step S10). Thereafter, the AP scan control (step S1) is started again after the set timer 2 has elapsed. This AP scan control is repeated every time the timer 2 elapses.

Next, a change in the scan cycle by the above access point scan control will be described with reference to a time chart.
FIG. 5 is a time chart for explaining a scan cycle by the access point scan control of the wireless LAN according to the embodiment of the present invention. FIG. 5A shows the received signal strength of each AP in the movement example of the wireless LAN access point and the portable wireless terminal in FIG. FIG. 5B shows a scan cycle at that time. T0 to t10 shown on the time axis are the same as t0 to t10 in FIG. These t0 to t10 are given for explaining the moving speed of the portable wireless terminal. The variable scan cycle timing at which the access point scan control is activated is a timing that is finer than t0 to t10 and is not directly related.

  At timing t0, it is assumed that the mobile wireless terminal exists in AP0 and remains without moving. In that case, there is no fluctuation in the received signal strength (reference numeral 70 in FIG. 5A), and in AP scan control, a negative value “−TS” is set as ΔT that increases or decreases the scan period by unit time (FIG. 4). In step S66), this decrease continues, and the scan cycle becomes the lower limit (reference numeral 71 in FIG. 5B). As described above, when the AP is stopped, the AP can be detected quickly by shortening the scan cycle.

  From t0 to t1, t2, and t3, the portable wireless terminal is moving at high speed. At t1, it is out of range. At t2, it is within AP1, but the mobile radio terminal is moving at a high speed, and therefore the fluctuation in received signal strength is large (reference numeral 72 in FIG. 5A). As described above, in the out-of-service state and the state in which the received signal strength varies greatly, in AP scan control, a positive value TL is set as ΔT that increases or decreases the scan cycle by unit time (step S65 in FIG. 4). The continuous increase (reference numeral 73 in FIG. 5B) and the upper limit clamp (reference numeral 74 in FIG. 5B) continue. Thus, during out-of-service or high-speed movement that is not suitable for a wireless LAN, the scan cycle is increased to save power.

  It is assumed that the portable wireless terminal is moving at a low speed from t3 to t5. In this case, the fluctuation of the received signal strength is small (reference numeral 75 in FIG. 5A), and in AP scan control, a negative value “−TS” is set as ΔT that increases or decreases the scan period by unit time (FIG. 4). In step S66), this decrease continues (reference numeral 76 in FIG. 5B), and the scan cycle becomes the lower limit value (reference numeral 77 in FIG. 5B). As described above, during a low-speed movement in the AP, the AP detection can be performed quickly by shortening the scan cycle. After t5, the example is similar and will not be described.

  According to the embodiment of the present invention, when out of service area or during high-speed movement that is not suitable for a wireless LAN, the scan cycle is lengthened to save power. During low-speed movement suitable for a wireless LAN, AP detection can be performed quickly by shortening the scan cycle.

  Next, another embodiment obtained by modifying the embodiment shown in FIGS. 3 and 4 will be described. 3 and 4, the timing for executing the AP scan result analysis process (step S6) is set to a constant period longer than the variable period of the access point scan control (step S2). However, when the variable cycle of the access point scan control (step S2) is relatively long, the timing for executing the AP scan result analysis process (step S6) is set to the same timing as the variable cycle of the access point scan control (step S2). May be.

For this purpose, the determination of the scan result analysis execution timing in step S5 in FIG. However, in this case, the scan result analysis execution timing becomes a variable period, and it becomes difficult to detect the moving speed of the portable wireless terminal. Therefore, in step S64 in FIG. The value is a variable specified value that matches the variable period. That is, the variable period is checked, and if the period is long, the predetermined specified value is increased. When the variable period is short, the predetermined specified value is decreased. That is, the variable specified value is set so that the slope is substantially constant when the horizontal axis is the variable period and the vertical axis is the variable specified value.
Also in this embodiment, the same effects as those in the embodiments of FIGS. 3 and 4 can be obtained.

The figure explaining the movement of the access point of a wireless LAN and a portable wireless terminal according to an embodiment of the present invention. The block diagram of the relevant part of the portable radio | wireless terminal which concerns on the Example of this invention. The operation | movement flowchart of the access point scan control part of the portable radio | wireless terminal which concerns on the Example of this invention. The operation | movement flowchart of the AP scan result analysis process in the access point scan control part of the portable radio | wireless terminal which concerns on the Example of this invention. The time chart explaining the scanning period by access point scan control of wireless LAN which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main control part 2 Timer 3 Wireless LAN antenna 4 Wireless LAN control part 5 Wireless LAN communication part 6 Various setting control part 7 Access point scan control part 8 This time scan result information memory 9 Previous scan result information memory 10 Authentication control part 11 Connection communication Control unit 12 Cutting control unit 100 Portable wireless terminal

Claims (4)

Timer,
A scan processing means that is periodically started by the timer, receives a signal from an access point for wireless LAN communication, measures received signal quality, and identifies the access point;
Scanning result analysis processing means that is periodically started by the timer and sets the timer period to be longer when the fluctuation amount of the received signal quality per predetermined period is greater than a predetermined value. A portable radio terminal. Timer,
A scan processing means that is periodically started by the timer, receives a signal from an access point for wireless LAN communication, measures received signal quality, and identifies the access point;
Periodically started by the timer, when there is no access point, when the access point for each predetermined period is different, or when the variation amount of the received signal quality for each predetermined period is larger than a predetermined value, the period of the timer is set. Scan result analysis processing means that is set to be long, and when the access point for each predetermined period is the same and the fluctuation amount of the received signal quality for each predetermined period is smaller than a predetermined value, the timer period is set to be short A portable wireless terminal comprising: Timer,
A scan processing means that is periodically started by the timer, receives a signal from an access point for wireless LAN communication, measures received signal quality, and identifies the access point;
If the fluctuation amount of the received signal quality per predetermined cycle is greater than a predetermined value for an access point that is periodically started by the timer and the identified access point is not registered as a connection target, the timer cycle is increased. A portable wireless terminal comprising: a scan result analysis processing unit configured to be configured as described above. Timer,
A scan processing unit that is activated by the timer in a first period, receives a signal from an access point for wireless LAN communication, measures received signal quality, and identifies the access point;
Scan result analysis processing that is started in a second period different from the first period and sets the timer period to be longer when the amount of fluctuation of the received signal quality per predetermined period is greater than a predetermined value A portable wireless terminal.

Images