Nippon Telegraph and Telephone Corporation

Nobuaki Otsuki

Naoki Kita

Kota Ito

Mizuki Suga

Yusuke Asai

Takatoshi Sugiyama

Yushi Shirato

Chunhsiang Huang

An APand STAsacquire time information from an external device, and synchronize time. The APsets, in a first signal, a transmission start time of the first signal, and transmits the first signal to the STA. The STAstransmit, to the AP, a second signal in which a delay time is set, the delay time being calculated from a difference between the transmission start time acquired from the first signal and a reception start time of the first signal at the own station. The APacquires delay time from the second signal of each STA, decides a timing for permitting transmission by each of the STAsby time division, on the basis of the acquired delay time, and notifies the STAsthereof. The STAseach effect control to start transmission of signals to the APat the timing notified from the AP

Wireless communication system, access point apparatus, wireless station apparatus and wireless communication method

Provided is a wireless relay system including multiple terminal station apparatuses and a base station apparatus. The base station apparatus includes: a base station reception unit that respectively receives pieces of upstream data traffic from the multiple terminal station apparatuses; an encoding unit that, if pieces of upstream data traffic that require mutual forwarding in opposite directions are present in the respective pieces of upstream data traffic, performs network encoding on the respective pieces of upstream data traffic such that the pieces of upstream data traffic are pieces of data traffic of mutually identical content; and a base station transmission unit that simultaneously transmits encoded data traffic as downstream data traffic to the multiple terminal station apparatuses. The terminal station apparatuses each include: a terminal station transmission unit that transmits the upstream data traffic to the base station apparatus; a terminal station reception unit that receives the encoded data traffic; and a decoding unit that decodes the encoded data traffic using the upstream data traffic.

Wireless relay system, wireless relay method and base station apparatus

A master station device is connected to a slave station device that emits a transmission signal received by light via an optical transmission path from a plurality of antenna elements. The master station device includes an optical signal output unit that outputs optical signals of a plurality of wavelengths, a phase adjustment unit that adjusts, for each wavelength, a phase of the transmission signal based on phase rotation that the optical signal is to undergo while being transmitted through the optical transmission path and a phase in one of the antenna elements corresponding to the wavelength of the optical signal, an optical modulation unit that modulates, for each wavelength, the optical signal output by the optical signal output unit with the transmission signal the phase of which is adjusted in accordance with the wavelength of the optical signal, and an optical combining unit that multiplexes the optical modulated signal of each wavelength and outputs the multiplexed signal to the optical transmission path. The slave station device includes an optical demultiplexing unit that demultiplexes the optical modulated signal transmitted through the optical transmission path and an optical/electric conversion unit that outputs the transmission signal obtained by converting the optical modulated signal of each wavelength into an electric signal to one of the plurality of the antenna elements corresponding to the wavelength.

Wireless communication system, parent station apparatus and wireless communication method

A wireless transmitter/receiver generates a first signal which notifies timing of a time slot allocated to each wireless station device, a conversion unit converts the first signal into an optical signal, and each of a plurality of antenna units converts the first signal from the optical signal into an electrical signal and transmits the electrical signal wirelessly. The wireless station device transmits a second signal at the timing reported by the first signal. Each of the plurality of antenna units converts the second signal wirelessly received from each wireless station device into an optical signal, and the conversion unit converts the second signal from the optical signal into an electrical signal. The wireless transmitter/receiver calculates, for each wireless station device, a transmission delay by using a difference between a reception time of the second signal and a reception time of a signal transmitted at the allocated timing by the wireless station device when it is assumed that there is no transmission delay. The wireless transmitter/receiver determines guard time between the time slots allocated to the wireless station devices based on the transmission delays of the wireless station devices.

Optical wireless communication system, wireless transmitting/receiving apparatus and optical wireless communication method

Provided is a wireless communication system employing network coding which can set transmission quality for each destination of packets and improve throughput. The wireless communication system is provided with a wireless relay station apparatus and wireless terminal station apparatuses. The wireless relay station apparatus selects coding rates to be used for a first packet and a second packet in accordance with communication quality required for the first packet and the second packet, generates error correction encoded packets having the same data length from the first packet and the second packet using the selected coding rates, performs network encoding on the error correction encoded first and second packets to generate a network encoded packet, and transmits the generated network encoded packet. The wireless terminal station apparatus performs error correction encoding on a third packet equal to one of the first and second packets, performs network decoding on a received network encoded packet using the error correction encoded third packet to generate a decoded packet, and performs error correction decoding.

Growing community of inventors

Musashino, Japan

Nobuaki Otsuki