Abstract: There is provided a wireless communication system that is capable of preventing interference with a primary use system caused by a CPE emitting radio waves at a frequency which is not a transmittable frequency before acquiring a list of transmittable frequencies based on its position information. In a wireless communication system that uses white space, a BS 10 and a CPE 22 store a specific frequency which is guaranteed to not interfere with a primary user. The BS 10 regularly switches between a first period when communication is performed at an operating frequency that uses white space and a second period when communication is performed at the specific frequency.

Abstract: 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.

Abstract: The present invention provides a wireless communication terminal which can flexibly select a base station according to communication quality and a load status and improve communication quality which a user experiences in a wireless communication system which does not include a handover mechanism and is not notified of availability of radio resources from each base station.

Abstract: A method for adjusting a transmission timing of a terminal station, which is performed at a base station in a Time-Division Duplex communication system, is disclosed. The method includes (a) receiving ranging signals or other reference signals, transmitted from a terminal station; (b) determining whether transmission timing at the terminal station is appropriate or not, by referring to the ranging signals transmitted from the terminal station; and (c) transmitting a value for adjusting the transmission timing at the terminal station. The value of the transmission timing is a value of the integral multiples of the timing offset detection capability of the ranging signal, or a value calculated by referring to the received reference signals, which have assigned with a different interval from an interval of the ranging signals.

Abstract: The present invention provides a wireless communication terminal which can flexibly select a base station according to communication quality and a load status and improve communication quality which a user experiences in a wireless communication system which does not include a handover mechanism and is not notified of availability of radio resources from each base station.

Abstract: To establish a wireless link with a terminal station without interfering with a primary user of a frequency, in a system and method in which a base station accesses a management apparatus for managing the frequency available for wireless communication via the wireless link with the terminal station.

Abstract: To establish a wireless link with a terminal station without interfering with a primary user of a frequency, in a system and method in which a base station accesses a management apparatus for managing the frequency available for wireless communication via the wireless link with the terminal station.

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.

Abstract: Provided is a wireless communication system that is capable of preventing interference between secondary use systems that do not use a database. The wireless communication system uses a white space for opposing communication between a base station and a terminal station. At startup, the base station transmits a preamble over a cycle that is n-times a frame length (where n is an integer 2 or greater), changes a set frequency channel if ranging is not detected from a terminal station within a fixed time interval, and begins normal operation using the set frequency channel if ranging is detected. At startup, the terminal station detects a preamble within a received signal, changes a set frequency channel if a peak is detected at each frame length, and transmits a ranging signal if peaks are detected for cycles that are n-times the frame length and peaks are not detected for other cycles.

Abstract: 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.

Abstract: There is provided a wireless communication system that is capable of preventing interference with a primary use system caused by a CPE emitting radio waves at a frequency which is not a transmittable frequency before acquiring a list of transmittable frequencies based on its position information. In a wireless communication system that uses white space, a BS 10 and a CPE 22 store a specific frequency which is guaranteed to not interfere with a primary user. The BS 10 regularly switches between a first period when communication is performed at an operating frequency that uses white space and a second period when communication is performed at the specific frequency.

Abstract: 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.

Abstract: In a wireless communication system, an APM provides sequential numbers to channels formed by dividing a specific frequency band, selects the channels in bit-reversed order of the numbers to divide the channels in frequency groups, creates a small hopping table for each frequency group, and generates a hopping table using the plurality of small hopping tables, and an AP performs channel access to a STA by frequency hopping with reference to the hopping table.

Abstract: In the wireless communication system, each of a base station 11 and a terminal station 12 obtains its location information, and upon establishment of synchronization, the terminal station 12 transmits a terminal station free channel list and its location information by extremely low power wireless communication, and the base station 11 compares a base station free channel list created based on information from a database 40 with the terminal station free channel list from the terminal station 12, and determines, when there is a common free channel, the free channel as uplink/downlink channels and determines, when there is no common free channel, an uplink channel and a downlink channel as different channels, calculates a base station-terminal station distance from the location information of the base station 11 and the location information of the terminal station 12, and determines terminal station's uplink transmission power based on the distance.

Abstract: 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.

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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In a wireless communication system, an APM provides sequential numbers to channels formed by dividing a specific frequency band, selects the channels in bit-reversed order of the numbers to divide the channels in frequency groups, creates a small hopping table for each frequency group, and generates a hopping table using the plurality of small hopping tables, and an AP performs channel access to a STA by frequency hopping with reference to the hopping table.