JP2011009991A - Wireless communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication apparatus capable of securing more stable radio communication than ever, and suppressing a cell search time in a cell search including an initial cell search requiring the longest search time.SOLUTION: In a communication function unit 120, a search frequency is determined according to a sequence preset in a frequency list, so as to search a base station by the search frequency. If the receiving power of a common pilot channel corresponding to a detected scramble code exceeds a threshold, the search of the base station is completed at that time, and a base station corresponding to the receiving power exceeding the threshold is determined to be a base station to be connected. When the base station search by the entire frequencies described in the frequency list is carried out, if the entire receiving power is lower than, inclusive of, the threshold, the wireless communication apparatus determines a base station having a preserved tentative effective cell to be the base station to be connected.

Description

  The present invention relates to a wireless communication apparatus that communicates with a base station using cellular communication using W-CDMA (Wideband-Code Division Multiple Access).

  In the W-CDMA system, since a radio link is established with a base station, it is necessary for the radio communication apparatus to establish downlink spread code synchronization. This process of establishing downlink spread code synchronization is called cell search and detects a scramble code of a common pilot channel (CPICH) that is a reference signal in the downlink. Cell search includes, for example, an initial cell search that searches for a base station to which a radio link is to be connected at the time of power-on of the radio communication device, a cell search during communication that searches for a handover destination base station, and a radio link that is connected when waiting for communication Cell search at the time of standby for searching for a base station to perform. In the W-CDMA system, in order to realize a high-speed cell search, three-stage cell search including slot timing detection (STEP 1), frame timing detection and scramble code group specification (STEP 2), and scramble code specification (STEP 3). Is adopted.

  In the initial cell search that requires the longest search time, a search is performed on a frequency basis to determine whether there is a communicable base station. At that time, only a frequency that has been connected in the past, called a priority frequency, is used. If a base station suitable for communication is found as a result of the search, broadcast information is received at that frequency, and then location registration processing is performed. In this initial cell search, a cell search can be quickly performed by performing a search preferentially from the frequency at which the base station existed and performing a location registration as soon as a base station suitable for communication is found.

  A typical example of the conventional cell search is the conventional cell search described in Patent Document 1. In the conventional cell search described in Patent Document 1, after detecting slot timing (STEP 1), detecting frame timing and specifying a scramble code group (STEP 2), identifying a scramble code number using a common pilot channel After that, in order to reduce false synchronization, confirmation by a threshold value (fixed value) using a common pilot channel is performed (see FIG. 10 of Japanese Patent Laid-Open No. 2002-118496).

Japanese Patent Application Laid-Open No. 2002-118496

  However, in the conventional cell search described in Patent Document 1, if the failure failure rate due to the threshold value increases, it is necessary to perform a re-search. Since the threshold used for level comparison with the output of the adder is a fixed value, it cannot cope with fluctuations in the output of the power adder due to phase fluctuations, resulting in false detection and inability to connect to the base station was there.

  In addition, in the conventional cell search, even if the field strength is low at the frequency at which the search was first performed, if a communicable base station is found, there is a base station with a higher field strength at another frequency. Since communication is performed with a base station having a poor reception status, adverse effects such as a decrease in reception rate and re-frequency change processing occur.

  An object of the present invention is to provide a radio communication apparatus capable of ensuring stable radio communication and suppressing the cell search time in a cell search including an initial cell search that requires the longest search time compared to the prior art. It is in.

The present invention is a wireless communication device that wirelessly communicates with a base station,
A base station detecting means for determining a search frequency according to a preset frequency list and searching for a base station at the search frequency;
Comparison means for comparing the received power of the received signal from the base station detected by the base station detection means and a preset threshold value;
If the received power exceeds the threshold value as a result of the comparison by the comparing means, the base station search is terminated at that time, and the base station corresponding to the received power exceeding the threshold value First determining means for determining as a base station to be connected;
As a result of the comparison by the comparison means, if the received power is equal to or lower than the threshold value, the value of the received power and the search frequency corresponding to the received power as a temporary effective cell as a candidate for a base station to be connected Storage means for associating and storing the information in the storage element;
When searching for base stations at all frequencies in the frequency list and all received power is below the threshold, the base station of the temporary effective cell stored in the storage element is connected. And a second means for determining as a base station to be
When the storage means stores the received power value and the search frequency information in the storage element, if the temporary effective cell is already stored in the storage element, the received power value of the temporary effective cell. And the value of the received power to be stored, and if the value of the received power to be stored is larger than the value of the received power of the valid cell, the received power value and search frequency information of the temporary valid cell Is replaced with the received power value and the search frequency information to be stored, and if the received power value to be stored is equal to or lower than the received power value of the valid cell, the received power value to be stored and the Disclosed is a wireless communication apparatus characterized by suppressing storage of search frequency information.

  The wireless communication apparatus of the present invention can realize more stable wireless communication than before, and an increase in cell search time is effectively suppressed, so that both cell search time and stable communication can be achieved.

  Since the wireless communication apparatus of the present invention can appropriately change the threshold value to the optimum value according to the installation conditions, the communication quality can be easily improved.

  The wireless communication apparatus of the present invention saves power because the temporary effective cell is replaced.

It is a block diagram which shows the outline | summary of one Embodiment of the radio | wireless communication apparatus of this invention. It is a block diagram which shows an example of the outline | summary of the form which connected the radio | wireless communication apparatus of this invention to the data terminal device. It is a flowchart which shows an example of the procedure from the cell search of an initial cell search to a standby state in the radio | wireless communication apparatus of this invention. It is a flowchart which shows another example of the procedure from the cell search of an initial cell search to a standby state in the radio | wireless communication apparatus of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  The wireless communication apparatus of the present invention communicates with a base station using cellular communication using, for example, W-CDMA (Wideband-Code Division Multiple Access). For example, as shown in FIG. 1, the wireless communication device of the present invention may be a mobile communication terminal 100 that is equipped with an antenna unit 110, a communication function unit 120, a display unit 130, and an operation unit 140 on the premise of movement. As shown in FIG. 2, it is connected to a data terminal equipment (DTE) 200 such as a vending machine, and has an antenna unit 110, a communication function unit 120, a display unit 130, an operation unit 140, and a data terminal device 200. The wireless communication terminal 101 that is connected to the processing unit 210 and includes the communication control unit 150 that controls data communication with the data terminal device 200 and is not premised on movement may be used.

  An example of the procedure from the cell search in the initial cell search to the standby state in the wireless communication apparatus of the present invention will be described with reference to FIGS.

  The initial cell search is performed by the communication function unit 120, for example, when the power key of the operation unit 140 is pressed to turn on the power or when the power is reset. First, the communication function unit 120 acquires a frequency list for performing an initial cell search from the storage element (S101, S201). The frequency list is not particularly limited as long as the search frequency is set in advance, the search order may be set in advance, or the priority frequency list that defines the order of search in the order of the frequency connected to the frequency connected in the past. (S201). The storage element only needs to be able to store the frequency list, and may be, for example, a volatile memory or a nonvolatile memory. Next, after setting i = 0 (initial value) (S102, S202), a search for a base station at the first frequency in the frequency list is performed (S104, S204). A channel scramble code is detected (S105, S205).

  When the detection means cannot detect the scramble code of the common pilot channel (S105 / No, S205 / No), i = i + 1 (S108, S208), and the search sequentially different in the order arranged in the frequency list. The base station is searched for the frequency (S104, S204), and the signal from the base station, that is, the base station is detected by the detecting means of the communication function unit 120. For example, the scramble code of the common pilot channel is detected (S105, S205).

  When the detection means can detect the scramble code of the common pilot channel (S105 / Yes, S205 / Yes), the reception power of the common pilot channel corresponding to the scramble code detected by the comparison means of the communication function unit 120 ( The received electric field intensity of the received signal is compared with a threshold value that can be changed as appropriate (S106, S206).

  The threshold value may be defined on a program, or may be stored in a non-volatile memory (NVM). It is preferable to store the threshold value in the nonvolatile memory because the threshold value can be appropriately changed according to the situation. When the wireless communication apparatus of the present invention is used for machine-to-machine communication such as a bus location system or vending machine inventory management, the installation condition (location, movement space, etc.) is adjusted by adjusting the threshold value. Therefore, it is possible to easily improve the communication quality easily.

  If the received power of the common pilot channel exceeds the threshold value as a result of the comparison by the comparison means (S106 / Yes, S206 / Yes), the base station search is terminated at that time, and the communication function unit 120 The base station corresponding to the received power exceeding the threshold is determined as a base station to be connected (S111, S211).

  As a result of the comparison by the comparison means, when the received power of the common pilot channel is equal to or less than the threshold value (S106 / No, S206 / No), the storage means of the communication function unit 120 stores the storage element of the communication function unit 120. If there is a received power value of a temporary effective cell as a candidate of a base station to be connected, which is recorded in, after reading the received power value, the received received power value of the temporary effective cell and the received power of the common pilot channel If the received power of the common pilot channel exceeds the received power value of the temporary effective cell, it is determined that the base station corresponding to the received power is a candidate for a base station that can obtain an effective electric field strength. While replacing the base station of the effective cell with the base station corresponding to the received power, the received power value of the temporary effective cell is replaced with the received power, and the base station of the temporary effective cell and the temporary effective cell Save in association with transmission power value and the search frequency (S107, S207). If the received power of the common pilot channel is equal to or less than the received power value of the temporary effective cell, the storage means does not store the received power of the common pilot channel to be stored or the search frequency in the storage element. Note that the storage means, when registering the reception power and search frequency of the common pilot channel, if no reception power value or search frequency as a temporary effective cell has been registered yet in the storage element, Stores received power and search frequency. Here, the contents registered in the storage element by the storage means as the temporary effective cell information are not limited to the contents described above in the present invention, and the storage means can specify at least the received power value and the base station or search frequency. (Search frequency information) may be stored. Thereafter, after setting i = i + 1 (S108, S208), the base station search is sequentially performed at different frequencies according to the order of the frequency list (S104, S204), and the detection unit of the communication function unit 120 detects the common pilot channel. A scramble code is detected (S105, S205).

  When the base station is searched for all the frequencies listed in the frequency list (S103 / No, S103 / No), the second determining means checks whether there is a temporary valid cell stored in the storing means. (S109, S209) When there is a temporary effective cell (S109 / Yes, S209 / Yes), the base station of the temporary effective cell stored in the storage means is determined as the base station to be connected (S111, S211). . As a result, both shortening of the cell search time and wireless communication with a stable electric field strength are realized.

  After the base station to be connected is determined (S111, S211), the information receiving means performs broadcast information reception processing on the determined base station to be connected (S112, S212). The broadcast information includes, for example, base station specific information, control information from the base station, information on neighboring cells of the general public base station where the mobile station is located, and the like. After the broadcast information reception process is completed, the position registration process is performed at the search frequency stored in the storage unit (S113, S213), and then the standby state is displayed, and the display unit 130 displays the range (S114). , S214).

  When the second determination means confirms whether or not there is a temporary valid cell stored in the storage means (S109), if there is no temporary valid cell (S109 / No), it is displayed on the display unit 130 as out of range ( S110). When emphasizing the realization of stable wireless communication rather than shortening of the cell search time, as shown in FIG. 4, the presence or absence of a temporary effective cell stored in the storage means is confirmed (S209). If there is no (S209 / No), a cell search may be performed for frequencies other than the priority frequency list, or a cell search may be performed for all frequencies (S210).

  A specific example of an information processing procedure when the wireless communication device of the present invention is connected to a data terminal device is shown below. When the data terminal device 200 of the present invention is a vending machine, when the wireless communication terminal 101 receives a transmission request for inventory information of the data terminal device 200 via the antenna 110, the communication control unit 150 of the wireless communication terminal 101 is used. Transmits a request for transmitting inventory information to the processing unit 210 of the data terminal device 200. The processing unit 210 of the data terminal device 200 manages information in the data terminal device 200 and performs processing in response to a transmission request for inventory information received from the wireless communication terminal 101. After that, the communication control unit 150 that has received the inventory information related to the transmission request from the processing unit 210 of the data terminal device 200 transmits the transmission request received from the data terminal device 200 to the request source of the inventory information transmission request by the communication function unit 120. The inventory information concerning is transmitted.

DESCRIPTION OF SYMBOLS 100 Mobile communication terminal 101 Wireless communication terminal 110 Antenna part 120 Communication function part 130 Display part 140 Operation part 150 Communication control part 200 Data terminal device 210 Processing part

Claims (1)

A wireless communication device that wirelessly communicates with a base station,
A base station detecting means for determining a search frequency according to a preset frequency list and searching for a base station at the search frequency;
Comparison means for comparing the received power of the received signal from the base station detected by the base station detection means and a preset threshold value;
If the received power exceeds the threshold value as a result of the comparison by the comparing means, the base station search is terminated at that time, and the base station corresponding to the received power exceeding the threshold value First determining means for determining as a base station to be connected;
As a result of the comparison by the comparison means, if the received power is equal to or lower than the threshold value, the value of the received power and the search frequency corresponding to the received power as a temporary effective cell as a candidate for a base station to be connected Storage means for associating and storing the information in the storage element;
When searching for base stations at all frequencies in the frequency list and all received power is below the threshold, the base station of the temporary effective cell stored in the storage element is connected. And a second means for determining as a base station to be
When the storage means stores the received power value and the search frequency information in the storage element, if the temporary effective cell is already stored in the storage element, the received power value of the temporary effective cell. And the value of the received power to be stored, and if the value of the received power to be stored is larger than the value of the received power of the valid cell, the received power value and search frequency information of the temporary valid cell Is replaced with the received power value and the search frequency information to be stored, and if the received power value to be stored is equal to or lower than the received power value of the valid cell, the received power value to be stored and the A wireless communication apparatus that suppresses storage of search frequency information.

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