# US 9,438,329 B2 · Wireless communication system

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- Number: US 9,438,329 B2
- Document ID: US9438329B2
- Status: Granted
- Kind: B2
- Application number: 14/647,181
- Filed: 2013-11-19
- Published: 2015-10-29
- Granted: 2016-09-06
- Earliest claimed: 2012-12-05
- Assignees: Hitachi Kokusai Electric Inc.
- Applicants: Hitachi Kokusai Electric Inc.
- Inventors: Keat Beng Toh; Masayuki Takekawa; Keigo Hasegawa
- Web page: https://patentgrep.com/patent/US9438329B2

## CPC

- H04B 7/086: {using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming}
- H04W 24/02: Arrangements for optimising operational condition
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A wireless communication terminal includes: an array antenna; a MAC processing section, provided to detect a first order system, that interprets information on a quiet period that the base station has informed of the MAC processing section in advance and generates a quiet period signal; a synthesizing section that weights signals received by antennas of the array antenna by using weighting coefficients, and combines the signals to produce a synthetic signal; and an array antenna control section that optimizes the weighting coefficients so as to reduce an interference signal received from the array antenna, over a period of presence of the quiet period signal. The optimized weighting coefficients are applied while downstream signals from the base station are being received, but are not applied while the primary usage system is being detected.

## Claims

### Claim 1

A wireless communication system including a wireless communication terminal that communicates with a base station at a frequency in a white space, the wireless communication terminal comprising:
an array antenna;
a MAC processing section provided to detect a first order system, the MAC processing section interpreting information on a quiet period that the base station has informed of the MAC processing section in advance, and generating a quiet period signal;
a synthesizing section weighting signals received from antennas of the array antenna by using weighting coefficients, and combining the signals to produce a synthetic signal; and
an array antenna control section optimizing the weighting coefficients so as to reduce an interference signal received by the array antenna, over a period of presence of the quiet period signal.

### Claim 2 (depends on 1)

The wireless communication terminal according to claim 1, wherein
the array antenna control section performs the optimization such that a signal-to-interference ratio is maximized.

### Claim 3 (depends on 2)

The wireless communication terminal according to claim 2, wherein
the antennas of the array antenna operate at different frequencies, and one of the antennas which is the most compatible with a transmission frequency is used for transmission, and
the synthetic signal produced by the synthesizing section is handled as a signal received by a single antenna.