Receiver of carrier sense multiplexing connection method and interference suppressing method thereof

• US 20060154628A1
• Filed: 05/26/2003
• Published: 07/13/2006
• Est. Priority Date: 05/27/2002
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Mochizuki, Takuji
• Granted Patent: US 8,761,704 B2
• Time in Patent Office: Days
• US Class Current: 455/134
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A broad band packet radio communication system is characterized by the carrier sense multiplexing connection method operated on a harsh frequency arrangement where an occupied band width of a modulation transmission/reception wave and a modulation side lobe are wide and the frequency channel interval is narrow. It is possible to improve the reception adjacent channel interference characteristic among a plurality of terminals belonging to the respective cells existing in the vicinity of adjacent frequency cell boundary area. The RSSI system is subjected to a narrow-band channel filtering (a narrow-band filter (BPF or LPF) having a band narrower than one-channel occupied band width) while the reception/demodulation system is subjected to a wide-band channel filtering (a wide-band filter (BPF or LPF) having a pass band equal to or wider than the one-channel occupied band width).

Claims

1. A receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

a received signal to a received signal strength indicator is subjected to narrowband filtering; and

a received signal to a demodulator is subjected to wideband filtering.

2. A superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to intermediate frequency after filtering the received signal by a narrow bandpass filter;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the intermediate frequency is demodulated after filtering the received signal by a wide bandpass filter.

9. The receiver claimed in claim 2, wherein:

the bandpass filter having a narrowband characteristic is provided with a passband narrower than one-channel modulation occupied bandwidth; and

the bandpass filter having a wideband characteristic is provided with a passband equal to or wider than the one-channel modulation occupied band width.

3. A superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by narrowband low-pass filters;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the baseband frequency is demodulated after filtering the received signal by wideband low-pass filters.

10. The receiver claimed in claim 3, wherein:

the low-pass filters having a narrowband characteristic are provided with a passband narrower than one half-channel modulation occupied bandwidth; and

the low-pass filters having a wideband characteristic are provided with a passband equal to or wider than the one half-channel modulation occupied band width.

4. A direct conversion receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by narrowband low-pass filters;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the baseband frequency is demodulated after filtering the received signal by wideband low-pass filters.

5. A superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to intermediate frequency after filtering the received signal by a variable bandpass filter controlled to have a narrowband characteristic;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the intermediate frequency is demodulated after filtering the received signal by the variable bandpass filter controlled to have a wideband characteristic.

8. The receiver claimed in claim 5, wherein:

the variable bandpass filter or the variable low-pass filters is/are controlled to have a narrowband characteristic in the initial state; and

the narrowband characteristic is changed to a wideband characteristic when the received signal is regarded as a carrier based on the carrier sense judgment result.

6. A superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by variable low-pass filters controlled to have a narrowband characteristic;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the baseband frequency is demodulated after filtering the received signal by the variable low-pass filters controlled to have a wideband characteristic.

7. A direct conversion receiver in a packet radio communication system using the carrier sense multiple access method, wherein:

electric field strength detection is performed for a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by variable low-pass filters controlled to have a narrowband characteristic;

a carrier sense judgment is made based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, the received signal whose frequency has been converted to the baseband frequency is demodulated after filtering the received signal by the variable low-pass filters controlled to have a wideband characteristic.

11. An interference suppression method for a receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal after narrowband filtering; and

demodulating a received signal after wideband filtering.

12. An interference suppression method for a superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to intermediate frequency after filtering the received signal by a narrow bandpass filter;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the intermediate frequency after filtering the received signal by a wide bandpass filter.

19. The interference suppression method claimed in claim 12, wherein:

the bandpass filter having a narrowband characteristic is provided with a passband narrower than one-channel modulation occupied bandwidth; and

the bandpass filter having a wideband characteristic is provided with a passband equal to or wider than the one-channel modulation occupied band width.

13. An interference suppression method for a superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by narrowband low-pass filters;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the baseband frequency after filtering the received signal by wideband low-pass filters.

20. The interference suppression method claimed in claim 13, wherein:

the low-pass filters having a narrowband characteristic are provided with a passband narrower than one half-channel modulation occupied bandwidth; and

the low-pass filters having a wideband characteristic are provided with a passband equal to or wider than the one half-channel modulation occupied band width.

14. An interference suppression method for a direct conversion receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by narrowband low-pass filters;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the baseband frequency after filtering the received signal by wideband low-pass filters.

15. An interference suppression method for a superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to intermediate frequency after filtering the received signal by a variable bandpass filter controlled to have a narrowband characteristic;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the intermediate frequency after filtering the received signal by the variable bandpass filter controlled to have a wideband characteristic.

18. The interference suppression method claimed in claim 15, wherein:

the variable bandpass filter or the variable low-pass filters is/are controlled to have a narrowband characteristic in the initial state; and

the narrowband characteristic is changed to a wideband characteristic when the received signal is regarded as a carrier based on the carrier sense judgment result.

16. An interference suppression method for a superheterodyne receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by variable low-pass filters controlled to have a narrowband characteristic;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the baseband frequency after filtering the received signal by the variable low-pass filters controlled to have a wideband characteristic.

17. An interference suppression method for a direct conversion receiver in a packet radio communication system using the carrier sense multiple access method, comprising the steps of:

detecting the electric field strength of a received signal which has undergone frequency conversion from radio to baseband frequency after filtering the received signal by variable low-pass filters controlled to have a narrowband characteristic;

making a carrier sense judgment based on the detection result; and

in the case where the received signal is regarded as a carrier based on the judgment result, demodulating the received signal whose frequency has been converted to the baseband frequency after filtering the received signal by the variable low-pass filters controlled to have a wideband characteristic.