Hitachi-Kokusai Electric Inc.

Keat Beng Toh

Keigo Hasegawa

Masayuki Takekawa

Kei Yanagisawa

Takehiko Kobayashi

Satoru Ejima

Seishi Sasaki

Madoka Tanaka

Tanaka Madoka

The present invention introduces a multichannel MAC into a white-space-using system. A base station and a terminal station are each configured from a plurality of wireless communication units and centralized control units thereof. Each of the wireless communication units wirelessly transmits/receives for one channel. The base station operates one or more channels according to white-space-channel status, and is assigned to a terminal station. When operating a plurality of channels, it is possible to select a redundancy mode for assigning data by duplicating the terminal-station data in a plurality of channels, and a high-speed mode for dividing the data and distributing the data among the plurality of channels.

Multichannel wireless communication system, base station, and method for using channel

Disclosed is a wireless communication system using white spaces and a base station that does not have its own backhaul, starts wireless communications without radiating radio waves of frequencies causing interference with primary users. A BS being in isolation starts a wireless communication with a CPE, connected to the internet, so as to access a database to acquire a list of frequencies available for transmission. The BS uses a predetermined frequency to perform the wireless communication with the CPE, and acquires, via this wireless communication, the list of frequencies available for transmission. Thereafter, the BS performs wireless communications with the CPE and with another CPE on the basis of the acquired list of frequencies available for transmission. The BS can hold, in advance, information of the predetermined frequency for which it has been estimated that the BS will cause no interference with the wireless communications of the primary users.

Relaying operation between base stations using white spaces in wireless access system

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.

Wireless communication system

A technique for enabling utilization of a one-way link in wireless communication systems of the type using whitespaces is disclosed. A wireless communication system is arranged to include a transmitting station which transmits data by wireless communication and receiving stations which receive data as sent thereto, for performing wireless communication by using a whitespace. The receiving station detects data receivability at a specific frequency and sends communication quality information which is a detection result thereof to the transmitting station. The transmitting station holds this communication quality information. Then, upon startup of data reception by wireless communication, the receiving station sends to the transmitting station a packet indicating required quality which is a condition for the data reception. The transmitting station selects, by reference to the communication quality information, a frequency satisfying this required quality and allocates it to the receiving station as a frequency used for data transmission.

System and method for selecting unlicensed frequency band using hybrid TDD and FDD

A base station judges whether backup channel of the base station has therein a channel which is not an operating channel of another base station configuring an adjacent cell by the channel management unit, and, if there is at least one channel which is not an operating channel of the another base station, performs fairness processing according to a prescribed etiquette to have one of the channels as an operating channel of the base station, and, if not, determines a base station which requests a release of an operating channel from the another based on the basis of a degree of satisfaction defined as a function of an offered communication traffic within a cell, a transmission rate depending on a propagation environment between the base station and a wireless communication terminal and an actually allocated operating channel number, and performs negotiation processing to cause a release of an operating channel.

Multichannel wireless communication system, base station, and channel using method

A network management unit included in a base station of WRAN, and a heterogeneous-systems coexistence function unit included in a relay station perform communications by taking advantage of the wireless line of WRAN. In this way, the network management unit and the heterogeneous-systems coexistence function unit make the determination and management of a frequency channel to be utilized by WLAN. Concretely, the QP (Quiet Period) of WRAN and that of WLAN are synchronized with each other with respect to the above-described frequency channel. During the synchronized QPs, WRAN and WLAN make the absence confirmation of a primary user.

Heterogeneous-systems coexistence method and wireless gateway apparatus

In a wireless communication system for performing wireless communication using a white space, a receiving station includes an interference suppression processing part which performs processing to reduce interference which is received by the signal transmitted from a transmitting station at a frequency of the white space, a receiving quality estimation part which estimates communication quality of the communication using the frequency of the white space based on the signal processed by the interference suppression processing part, and a receiving quality informing part which transmits to the transmitting station the communication quality information estimated by the receiving quality estimation part.

Wireless communication system and receiving device

The present invention is directed to reduction of operation amount of likelihood calculation (LLR calculation) in a communication apparatus for performing communications using an extended mapping in which a plurality of bit sequences are assigned to a single symbol point. A receiving unit receives a signal which is transmitted from a transmitting unit by using the extended mapping. A repetition process unit decodes the received signal from the receiving unit by calculating an LLR of the received signal and performing a repetition process. In this case, the LLR is calculated for every bit using a MAX-LOG approximation and a thus-derived approximation formula is multiplied by weighting factors corresponding to proportions of '0' and '1' in each bit assigned to a symbol point closest to the received signal.

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Tokyo, Japan

Keat Beng Toh