Nippon Telegraph and Telephone Corporation

Hiroshi Nakamoto

Yasushi Takatori

Kenichi Kawamura

Tomoyuki Yamada

Keisuke Wakao

Shota Nakayama

Satoshi Ikeda

Kiyomi Kumozaki

Koji Kikushima

Naoya Sakurai

Katsushi Iwashita

Nori Shibata

Kouichi Suto

Chisei Kishimoto

Provided is a wireless LAN system in which an interference control signal transmitter that is provided in the surroundings of the wireless LAN base station and the wireless LAN terminal, and is configured to collect wireless environment information regarding the interfering AP/STA, and transmit, to the interfering AP/STA, an interference control signal that is to be used to set a transmission waiting period; and an interference control signal management device configured to collect the wireless environment information from the interference control signal transmitter, determine the interference control signal transmitter whose communication area includes the interfering AP/STA based on the wireless environment information, and control the determined interference control signal transmitter to transmit the interference control signal to be used to set the transmission waiting period that corresponds to a length of time of the communication between the wireless LAN base station and the wireless LAN terminal, wherein while the interfering AP/STA that has received the interference control signal sets the transmission waiting period, the wireless LAN base station and the wireless LAN terminal preferentially perform communication.

Wireless LAN system and interference control method

A wireless LAN communication device generates an MPDU by attaching a MAC header to transmission data, generates an A-MPDU subframe by attaching an MPDU delimiter to the MPDU, generates an A-MPDU by aggregating a plurality of A-MPDU subframes, and transmits the A-MPDU. The wireless LAN communication device includes: an MPDU duplicating means for determining whether or not transmission data is a redundancy target according to a required quality of the transmission data, determining that an MPDU generated from the transmission data determined to be a redundancy target is a redundant MPDU, and generating a duplicate MPDU by duplicating the redundant MPDU; and an A-MPDU generating means for generating an A-MPDU that includes the redundant MPDU and the duplicate MPDU.

Wireless LAN communication device and wireless LAN communication method

The AM/FM converter of the present invention comprises an optical frequency modulation section which receives multi-channel AM video signals and outputs an optical-frequency-modulated optical signal beam; and an optical heterodyne detection section comprising an optical frequency oscillator composed of a semiconductor local laser which outputs a local oscillator optical beam having an optical frequency separated by a designated intermediate frequency, an optical coupler, and a photoelectric converter composed of a photodiode, which receives the optical signal beam and outputs an electrical batched FM modulation signal which is frequency-modulated and frequency-converted to the intermediate frequency. By means of this configuration, the invention offers an AM/FM converter wherein the frequency band is made considerably wider.

AM/PM converter and optical signal transmission system

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Kodaira, Japan

Hiroshi Nakamoto