JP2007235493A - Band search system and its method, and communication device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to shorten the processing time for band search on each mobile terminal in a mobile communication system. <P>SOLUTION: The diversity receiving method mobile terminal has receivers 5 and 7 of systems 1 and 2 and first and second antennas 10 and 11. When conducting a band search at the time of turning on the power or being out of service, it is so controlled by a control unit 1 that a necessary frequency band is divided into a plurality of frequencies (bandwidths), and half of the frequencies are searched for by the receiving portion 5 of system 1 while the other half of the frequencies are searched for by the receiver 7 of system 2. When a usable frequency is found by one of the systems, the band search by the other system is stopped, resulting in shortening the processing time for band search. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a band search system, a method thereof, and a communication apparatus using the same, and more particularly to a band search method for dividing a required frequency range into a plurality of frequencies and searching for an effective frequency from the plurality of frequencies.

  In a mobile communication system, a frequency obtained by dividing a predetermined frequency range into a plurality of frequencies (widths) is used as a frequency for transmission from a base station, that is, for reception by a mobile terminal. Radio waves are transmitted from the base station at these multiple frequencies. Therefore, the mobile terminal needs a band search process for examining the presence of radio waves of these frequencies when the power is turned on or out of service area (see Patent Document 1).

  In a conventional band search process, a method of sequentially searching for the presence / absence of radio waves at a number of set frequencies is common. Here, with reference to Patent Document 2, a technique is disclosed in which a plurality of antennas and a plurality of receivers corresponding thereto are provided to improve characteristics under multipath fading.

Japanese Patent Laid-Open No. 2003-244083 JP 2003-218756 A

  When a band search is performed in order for a required frequency (width) in one receiving unit, it takes time to search a large number of frequencies, and in particular, a waiting time is generated for the user before returning from outside the service area. It will be. In Patent Document 2, as described above, a plurality of antennas and a plurality of receivers corresponding to the antennas are provided to improve characteristics under multipath fading. Its purpose is completely different.

  An object of the present invention is to provide a band search system and method capable of shortening the processing time of the band search.

  A band search system according to the present invention is a band search system that divides a required frequency range into a plurality of frequencies and searches for an effective frequency from the plurality of frequencies. The band search system includes a plurality of receiving units and the plurality of receiving units. And a control unit that controls to perform different searches in parallel by sharing different frequencies.

  A band search method according to the present invention divides a required frequency range into a plurality of frequencies, and searches for an effective frequency from the plurality of frequencies, and assigns different frequencies to a plurality of receiving units. It includes a control step for controlling the search to be performed in parallel with each other.

  A communication apparatus according to the present invention includes the above-described band search system.

  The operation of the present invention will be described. In a diversity reception type mobile terminal having a 1-system and 2-system receiver and first and second antennas, when performing a band search when the power is turned on or out of service area, the required frequency range is set to a plurality of frequencies (widths). Division is performed, and control is performed so that half of the plurality of frequencies is searched by the 1-system receiving unit and the other half is searched by the 2-system receiving unit. If an effective frequency can be searched for in one system, the search processing in the other system is also stopped. Thereby, the processing time of the band search is shortened.

  According to the present invention, when performing a band search for a required frequency range, the search time can be significantly shortened by performing a parallel search while sharing different frequencies among a plurality of receiving units.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of a mobile terminal according to an embodiment of the present invention. This mobile terminal includes a control unit 1 that controls each unit, a PLL synthesizer 2 for a transmission unit for a transmission unit 3, a PLL synthesizer 4 for a 1-system reception unit for a 1-system reception unit 5, and a 2-system reception unit A PLL synthesizer 6 for the 2 system receiver for 7, an antenna duplexer 8 for the 1 system receiver 5 and the transmitter 3, an antenna switch 9 for switching the first and second antennas 10 and 11, The first and second antennas 10 and 11 are included.

  The transmission unit 3 includes a radio unit and a baseband processing unit to perform modulation processing, and the 1-system reception unit 5 and the 2-system reception unit 7 include a radio unit and a baseband processing unit to perform demodulation processing. The transmission unit PLL synthesizer 2 includes a VCO and a PLL synthesizer, and generates a local signal for the transmission unit 3.

  The 1-system receiver PLL synthesizer 4 includes a VCO and a PLL synthesizer, and generates a local signal for the 1-system receiver 5. The PLL synthesizer 6 for the 2 system receiver is composed of a VCO and a PLL synthesizer, and generates a local signal for the 2 system receiver 7. The duplexer 8 is used to share an antenna used for the transmission unit 3 and the 1-system reception unit 5, and is connected to the antenna changeover switch 9 by a 1-system TRX (transmission / reception) signal 12.

  The 2-system receiver is connected to the antenna changeover switch 9 by a 2-system RX (reception) signal 13. The antenna switching switch 9 switches the antenna that connects the first and second antennas 10 and 11 to the 1-system TRX signal 12 and the 2-system RX signal 13 by the antenna switching signal 14 from the control unit 1. An example of this antenna switching is shown in FIG.

  As shown in FIG. 2, when the antenna switching signal 14 is at a high level (H), the 1-system TRX signal 12 is connected to the first antenna 10 and the 2-system TRX signal 13 is connected to the second antenna 11, respectively. . In this case, diversity reception is performed. When the antenna switching signal 14 is at a low level (L), the 1-system TRX signal 12 is connected to the first antenna 10 and the 2-system TRX signal 13 is not connected. Received.

  Hereinafter, the operation of this embodiment will be described. FIG. 3 is a flowchart for explaining the operation of the present embodiment, where (A) shows the operation of the 1-system receiving unit 5 and the control unit 1, and (B) shows the operation of the 2-system receiving unit 7 and the control unit 1. Are shown respectively.

  When the mobile terminal is turned on or out of service, the 1-system receiver 5 and 2-system receiver 7 start a band search in parallel according to the flowchart shown in FIG. 3 (steps S1 and S11). In this case, the control unit 1 sets the antenna switching signal 14 to H.

  The frequencies to be band-searched by the 1-system receiver 5 and the 2-system receiver 7 are as shown in FIG. That is, the required frequency range is divided into upper and lower halves, and the 1-system receiver 5 sequentially receives the RSSI (Receive Signal Strength Indicator) from the first frequency N = 1 to the 100th frequency N = 100. Band search is performed until an effective frequency at which the received electric field intensity) is equal to or higher than a reference value (threshold value) is found (No in steps S2 to S6). On the other hand, the 2-system receiver 7 performs a band search in order from the 101st frequency N = 101 to the 200th frequency N = 200 until an effective frequency having an RSSI equal to or higher than the reference value is found (steps S12 to S12). No in S16).

  At this time, the control unit 1 sends control data to the 1-system receiver PLL synthesizer 4 and the 2-system receiver PLL synthesizer 6 according to the flowchart shown in FIG. 3 and the frequency table shown in FIG. The 1-system receiver PLL synthesizer 4 and the 2-system receiver PLL synthesizer 6 that have received the control data sequentially output local signals to the 1-system receiver 5 and the 2-system receiver 7, respectively. Thereby, the 1-system receiving unit 5 and the 2-system receiving unit 7 calculate the RSSI after converting the RF signal into a baseband signal, and determine a wave having a RSSI equal to or higher than a threshold value as a reference wave as an effective wave.

  In steps S6 and S16, if an effective wave whose RSSI is equal to or greater than the threshold value is found (Yes), the band search is terminated at that time, so control is performed to stop the band search in the other receiver (step S6). S7, S17), the entire band search process ends (steps S8, S18). In this way, the search time can be greatly shortened by sharing different frequencies and searching in parallel.

  Parameters for determining frequency validity / invalidity by band search (steps S6 and S16) are RSSI, RSCP (Received Signal Code Power), Ec / No (Ratio of Energy per Modulating Bit to the Noise Spectral Dencity). ) May be used.

  The calculation of the parameters for determining the effective frequency such as RSSI, RSCP, Ec / No can use an average value, a peak value in a predetermined time, or an integral value in a certain period.

  In addition, as an example of selecting the frequency to be searched by the 1-system receiving unit and the 2-system receiving unit, a receiving unit that searches in the higher frequency direction and a receiving unit that searches in the lower direction are selected based on the frequency used last time. May be. Furthermore, in a communication device such as a multiband-compatible mobile terminal, a plurality of receiving units may be further divided into different bands and searched.

  In the case of a TDMA communication terminal, the duplexer 8 shown in FIG. 1 can be replaced with a switch for switching between transmission and reception. The antenna switching signal 14 shown in FIG. 1 is generated based on frequency setting data set in the PLL synthesizer 4 for the 1-system receiving unit and the PLL synthesizer 6 for the 2-system receiving unit, or the 1-system receiving units 5 and 1 It is also conceivable to control the antenna changeover switch with a signal using a power-on signal of the system synthesizer PLL synthesizer 4, the system 2 receiver 7, and the system 2 receiver synthesizer 6.

  In the compressed mode, it is also conceivable to measure parameters such as RSSI of cells of different frequencies in the 2 system receiver while maintaining the current frequency setting in the 1 system receiver. Here, the compressed mode is a function for enabling measurement of cells of different frequencies in order to perform different frequency handover, compressing downlink transmission data to provide free time, and in this free time, It measures cells at different frequencies.

  In the above embodiment, the mobile terminal typified by a mobile phone has been described. However, the present invention can be widely applied to communication devices that perform band search.

It is a functional block diagram of the mobile terminal for demonstrating the Example of this invention. It is a figure which shows the relationship between the antenna switching signal of FIG. 1, and antenna selection. It is a flowchart which shows operation | movement of the Example of this invention. It is a figure which shows the example of the allocation state to a setting frequency and a receiving system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 PLL synthesizer for transmission parts 3 Transmission part 4 PLL synthesizer for 1 system receiving parts 5 1 system receiving parts 6 PLL synthesizer for 2 system receiving parts 7 2 system receiving parts 8 Duplexer 9 Antenna changeover switch 10 1st antenna 11 Second antenna

Claims (16)

  A band search system that divides a required frequency range into a plurality of frequencies and searches for an effective frequency from the plurality of frequencies, and assigns a plurality of receiving units and different frequencies to the plurality of receiving units. And a control unit that controls the search to be performed in parallel with each other.   The band search system according to claim 1, wherein the effective frequency determination parameter is one of RSSI, RSCP, and Ec / No.   3. The band search system according to claim 2, wherein the determination parameter is calculated using one of an average value, a peak value, and an integral value for a predetermined period.   The band search system according to any one of claims 1 to 3, wherein the control unit determines a frequency share to be searched based on a previous reception frequency.   The band search system according to any one of claims 1 to 4, wherein the receiving unit is a plurality of receiving units in a communication apparatus having a diversity receiving function.   The band search system according to claim 1, wherein the receiving unit is a plurality of receiving units in a multiband-compatible communication apparatus.   In the compressed mode for measuring different frequencies, the control unit performs control so as to perform a band search for cells of different frequencies in another receiving unit while maintaining the current frequency in one receiving unit. The band search system according to claim 1.   A band search method in which a required frequency range is divided into a plurality of frequencies and an effective frequency is searched from among the plurality of frequencies, and a plurality of receiving units are assigned different frequencies to perform a search in parallel with each other. A band search method characterized by including a control step for controlling to perform.   The band search method according to claim 8, wherein the effective frequency determination parameter is one of RSSI, RSCP, and Ec / No.   The band search method according to claim 9, wherein the determination parameter is calculated using one of an average value, a peak value, and an integral value for a predetermined period.   The band search method according to any one of claims 8 to 10, wherein in the control step, the frequency sharing to be searched is determined based on the previous reception frequency.   The band search method according to claim 8, wherein the receiving unit is a plurality of receiving units in a communication apparatus having a diversity receiving function.   The band search method according to claim 8, wherein the receiving unit is a plurality of receiving units in a multiband-compatible communication apparatus.   In the compressed mode for measuring different frequencies, the control step includes a step of controlling to perform a band search of cells having different frequencies in another receiving unit while maintaining the current frequency in one receiving unit. The band search method according to claim 8, wherein:   A communication apparatus comprising the band search system according to claim 1.   The communication apparatus according to claim 15, wherein the communication apparatus is a mobile terminal.

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