Mobile wireless terminal, a method of measuring signal strength of a received signal, and a method of searching for a base station

• US 8,676,137 B2
• Filed: 01/20/2012
• Issued: 03/18/2014
• Est. Priority Date: 11/27/2009
• Status: Expired due to Fees

• Current Assignee: Fujitsu Mobile Communications Limited (Fujitsu Limited)
• Original Assignee: Fujitsu Mobile Communications Limited (Fujitsu Limited)
• Inventors: Kubo, Yoshiyuki
• Primary Examiner(s): PATEL, MAHENDRA R
• Application Number:
  US13/354,914
• Publication Number:
  US 20120120999A1
• Time in Patent Office: 788 Days
• Field of Search: 455/67.11, 455/216, 455/550.1, 455/249.1, 455/22, 455/277.2, 455/506, 455/450, 455/434, 455/509, 455/454, 375/142, 375/146, 375/150, 375/295, 375/309, 370/335, 370/342, 370/330, 370/209
• US Class Current: 455/102
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

A mobile wireless terminal includes a wireless receiving part configured to receive a wireless signal from a base station which belongs to a mobile communication system using a time-frequency conversion for baseband processing; a received signal processing part that includes a time-frequency converting circuit and is configured to process the wireless signal; a setting part configured to successively set central frequencies within regions, wherein a frequency band that the mobile communication system uses is divided into the regions having a predetermined bandwidth; and a received signal strength measuring part configured to measure signal strength of received signals over the regions of the frequency band that the mobile communication system uses based on time-frequency conversion results from the time-frequency converting circuit, the time-frequency conversion results being obtained for the respective regions using the respective central frequencies set by the setting part.

Claims

1. A mobile wireless terminal comprising:

a wireless receiving part configured to receive a wireless signal from a base station which belongs to a mobile communication system using a time-frequency conversion for baseband processing;

a received signal processing part that includes a time-frequency converting circuit and is configured to process the wireless signal from the base station which belongs to the mobile communication system;

a setting part configured to successively set, in the wireless receiving part, central frequencies within regions, wherein a frequency band that the mobile communication system uses is divided into the regions having the same bandwidth or different bandwidths; and

a received signal strength measuring part configured to measure signal strength of a received signal in the received signal processing part over the regions of the frequency band that the mobile communication system uses based on time-frequency conversion results from the time-frequency converting circuit and during a time other than at the time of an intermittent reception in which a predetermined process is performed if the mobile wireless terminal performs an intermittent receiving operation at a predetermined intermittent receiving cycle, the time-frequency conversion results being obtained for the respective regions using the respective central frequencies set by the setting part, the respective central frequencies set by the setting part enabling searching for a base station which belongs to a second mobile communication system not using the time-frequency conversion for the baseband processing and using the measured signal strength.

2. A mobile wireless terminal comprising:

a wireless receiving part configured to receive a wireless signal from a base station which belongs to a first mobile communication system using a time-frequency conversion for baseband processing, or from a base station which belongs to a second mobile communication system not using the time-frequency conversion for the baseband processing;

a first received signal processing part that includes a time-frequency converting circuit and is configured to process the wireless signal from the base station which belongs to the first mobile communication system;

a second received signal processing part configured to process the wireless signal from the base station which belongs to the second mobile communication system;

a setting part configured to successively set, in the wireless receiving part, central frequencies within regions, wherein a frequency band that the second mobile communication system uses is divided into the regions having the same bandwidth or different bandwidths; and

a received signal strength measuring part configured to measure signal strength of a received signal in the first received signal processing part over the regions of the frequency band that the second mobile communication system uses based on time-frequency conversion results from the time-frequency converting circuit and during a time other than at the time of an intermittent reception in which a predetermined process is performed if the mobile wireless terminal performs an intermittent receiving operation at a predetermined intermittent receiving cycle, the time-frequency conversion results being obtained for the respective regions using the respective central frequencies set by the setting part, the respective central frequencies set by the setting part enabling searching for the base station which belongs to the second mobile communication system using the measured signal strength.

3. The mobile wireless terminal as claimed in claim 2, further comprising a base station searching part configured to search for the base station which belongs to the second mobile communication system via the wireless receiving part and the second received signal processing part, using the central frequency in which the received signal has the signal strength greater than a predetermined reference value.

4. The mobile wireless terminal as claimed in claim 3, wherein the base station searching part searches for the base station which belongs to the second mobile communication system via the wireless receiving part and the second received signal processing part, successively using the respective central frequencies in which the received signal has the signal strength greater than the predetermined reference value.

5. The mobile wireless terminal as claimed in claim 3, wherein the first mobile communication system is related to WiMAX or LTE, and the second mobile communication system is related to WCDMA, CDMA 2000 or GSM.

6. The mobile wireless terminal as claimed in claim 2, further comprising a storing part configured to store all the central frequencies in which the received signal has the signal strength greater than a predetermined reference value.

7. A mobile wireless terminal comprising:

a wireless receiving part configured to receive a wireless signal from a base station which belongs to a mobile communication system using a time-frequency conversion for baseband processing;

a received signal processing part that includes a time-frequency converting circuit and is configured to process the wireless signal from the base station which belongs to the mobile communication system;

a first setting part configured to successively set, in the wireless receiving part, central frequencies within regions, wherein a frequency band that the mobile communication system uses is divided into the regions having the same bandwidth or different bandwidths;

a detecting part configured to detect one or more null frequencies over the regions of the frequency band that the mobile communication system uses based on time-frequency conversion results from the time-frequency converting circuit, the time-frequency conversion results being obtained for the respective regions using the respective central frequencies set by the first setting part;

a second setting part configured to set, in the wireless receiving part, the null frequency detected by the detecting part as the central frequency; and

a received signal strength measuring part configured to detect a symbol including a sync signal appearing at a predetermined cycle in the wireless signal transmitted from the base station which belongs to the mobile communication system, and measure signal strength of a received signal in the received signal processing part based on a time-frequency conversion result from the time-frequency converting circuit and during a time other than at the time of an intermittent reception in which a predetermined process is performed if the mobile wireless terminal performs an intermittent receiving operation at a predetermined intermittent receiving cycle, the time-frequency conversion result being obtained for the symbol including the sync signal using the null frequency set as the central frequency by the setting part, the central frequency set by the setting part enabling searching for a base station which belongs to a second mobile communication system not using the time-frequency conversion for the baseband processing and using the measured signal strength.

8. The mobile wireless terminal as claimed in claim 7, further comprising a base station searching part configured to search for the base station which belongs to the mobile communication system via the wireless receiving part and the received signal processing part, using the central frequency in which the received signal has the signal strength greater than a predetermined reference value.

9. The mobile wireless terminal as claimed in claim 7, wherein the mobile communication system is a LTE system.

10. The mobile wireless terminal as claimed in claim 7, wherein if plural null frequencies are detected by the detecting part, the second setting part sets the respective frequencies as the central frequencies in the wireless receiving part, the received signal strength measuring part measures the signal strength of the received signal in the received signal processing part based on the time frequency conversion results from the time-frequency converting circuit, the time-frequency conversion results being obtained for the symbol including the sync signal using the null frequencies set to the central frequencies by the setting part.

11. The mobile wireless terminal as claimed in claim 7, further comprising a storing part configured to store the central frequency in which the received signal has the signal strength greater than a predetermined reference value.

12. The mobile wireless terminal as claimed in claim 7, wherein the sync signal includes at least a first sync signal and more than one second sync signal.