Abstract: A communication band is divided into: a beacon period in which every master station transmits a beacon packet in competition with one another; a guaranteed-band period (e.g., a TDMA period or an FDMA period) in which only a specific permitted station is allowed access; and a CSMA period in which every station is allowed access in competition with one another. Plural master stations exchange information of a communication band used in the guaranteed-band period with each other, and based on the respective information, a communication band available to the master station's own communications system in the guaranteed-band period is calculated.

Abstract: A method, performed by an access point controls transmission of a data stream from a station, by determining whether or not to admit the transmission of the data stream. The method includes receiving, from the station, a QoS registration request frame, indicating a request for transmission of a data stream, and including information indicating a QoS requirement comprising information indicating a required interval between a start of two successive time periods during which the station is permitted to transmit the data stream. A schedule for the transmission of the data stream subject to the QoS requirement is calculated when the transmission is admitted and a QoS registration response frame, including information indicating the schedule is transmitted to the station.

Abstract: A spreading code generating apparatus carries out M-sequence multiplication and zero value addition of generated orthogonal codes to obtain channel identification codes, and then carries out inverse Fourier transform of the channel identification codes to generate spreading codes and inverse spreading codes. A transmitting apparatus and a receiving apparatus store the spreading codes and the inverse spreading codes generated by the spreading code generating apparatus, respectively, and use a single code respectively selected from the stored codes to carry out spread spectrum communication. With the use of the spreading codes for spreading, the input signal is spread over a wide frequency band with uniform power on the frequency axis. Thus, transmission characteristics are improved, and multiplexing capacity is increased.

Abstract: A communication bandwidth is divided into a beacon period in which all master stations compete for transmission of a beacon packet, a first carrier sense multiple access (CSMA) period in which only authorized specific stations are allowed to compete for access, and a second CSMA period in which all stations are allowed to compete for access. The master stations exchange information with each other about a communication bandwidth being used in the first CSMA period, thereby calculating a communication bandwidth which can be used by each communication system in the first CSMA period, based on the information.

Abstract: The variation cycle L of the characteristics of a transmission line is divided into a plurality of sections (n sections), a procedure is repeated in which transmission line estimation is performed for only one section among n sections in one beacon period, and thus transmission line estimation is performed for all of the n sections. The beacon period T is set based on (T=L×m/n), where n is an integer that is 2 or larger, and m is an integer that is n or larger and whose greatest common measure with n is 1.

Abstract: A communication system includes a synchronizing signal generator that generates a synchronizing signal based on a timing of an alternating waveform in a power line, a data communicating circuit that performs the data communication, and a communication controller that controls to acquire a transmitting right utilizing a timing of the synchronizing signal and to control the communication circuit in accordance with whether or not the communication apparatus acquires the transmitting right.

Abstract: An access control method applicable to a network including a plurality of communication terminals for achieving simplification in processing, improvement in response, and efficient use of bands is provided. In a terminal station 21, a transmission information generating section 213 generates predetermined transmission information based on the amount of data stored in a buffer section 212. A packet transmitting section 214 generates a packet including data and the transmission information for transmission to another terminal station 22. In a control station 11, a packet receiving section 111 receives the packet transmitted by the terminal station 21. A transmission information obtaining section 112 analyzes the received packet to obtain the transmission information and, based on the transmission information, determines whether the band currently allocated is to be changed.

Abstract: A terminal of the present invention comprises a control frame detection portion of detecting a control frame issued from a control station, a control frame memory portion of storing control information contained in the control frame, a substitute frame issuance determination portion of determining to issue a substitute frame when the control frame is not detected until a predetermined first time period is elapsed, and a substitute frame issuance portion of creating a frame which is the same as or equivalent to the control frame, as the substitute frame, based on the control information stored in the control frame memory portion when the substitute frame issuance determination portion determine to issue the substitute frame, and issuing the created substitute frame.

Abstract: A communication system includes a synchronizing signal generator that generates a synchronizing signal based on a timing of an alternating waveform in a power line, a data communicating circuit that performs the data communication, and a communication controller that controls to acquire a transmitting right utilizing a timing of the synchronizing signal and to control the communication circuit in accordance with whether or not the communication apparatus acquires the transmitting right.

Abstract: An access control method applicable to a network including a plurality of communication terminals for achieving simplification in processing, improvement in response, and efficient use of bands is provided. In a terminal station, a transmission information generating section generates predetermined transmission information based on the amount of data stored in a buffer section. A packet transmitting section generates a packet including data and the transmission information for transmission to another terminal station. In a control station, a packet receiving section receives the packet transmitted by the terminal station. A transmission information obtaining section analyzes the received packet to obtain the transmission information and, based on the transmission information, determines whether the band currently allocated is to be changed. If a change is required, a packet transmitting section transmits a packet reporting a newly-allocated band to the terminal stations.

Abstract: A communication terminal which modulates and demodulates a packet for transmission and reception based on a communication parameter for modulation and demodulation determined according to a communication-medium characteristic. The communication terminal includes: an extracting unit which extracts, during every occurrence of a predetermined cycle, information indicative of either one of transmission efficiency and reception quality of the packet as an information element; a calculating unit which calculates a difference between a first information element extracted by the extracting unit and a second information element previously extracted by the extracting unit; and detecting-scheme performance determining unit which determines, based on the difference between the first information element and the second information element whether a scheme of detecting the communication-medium characteristic is to be performed.

Abstract: A communication terminal which modulates and demodulates a packet for transmission and reception based on a communication parameter for modulation and demodulation determined according to a communication-medium characteristic. The communication terminal includes: an extracting unit which extracts, during every occurrence of a predetermined cycle, information indicative of either one of transmission efficiency and reception quality of the packet as an information element; a calculating unit which calculates a difference between a first information element extracted by the extracting unit and a second information element previously extracted by the extracting unit; and detecting-scheme performance determining unit which determines, based on the difference between the first information element and the second information element whether a scheme of detecting the communication-medium characteristic is to be performed.

Abstract: The variation cycle L of the characteristics of a transmission line is divided into a plurality of sections (n sections), a procedure is repeated in which transmission line estimation is performed for only one section among n sections in one beacon period, and thus transmission line estimation is performed for all of the n sections. The beacon period T is set based on (T=L×m/n), where n is an integer that is 2 or larger, and m is an integer that is n or larger and whose greatest common measure with n is 1.

Abstract: In serial transmission of a mixture of isochronous data and anisochronous data, communications through a transmission path with a high ratio of occurrence of transmission errors may disturb images during streaming reproduction and produce noise in sound. To solve this problem, the isochronous data that has not been successfully received is retransmitted by using an anisochronous region. Thus, a transmission error of the isochronous data can be reduced without impairment of isochronous characteristics of the data.

Abstract: A communication system includes a synchronizing signal generator that generates a synchronizing signal based on a timing of an alternating waveform in a power line, a data communicating circuit that performs the data communication, and a communication controller that controls to acquire a transmitting right utilizing a timing of the synchronizing signal and to control the communication circuit in accordance with whether or not the communication apparatus acquires the transmitting right.

Abstract: When operating as a control terminal and recognizing interference from another logical network, a terminal apparatus determines whether or not a logical network to be controlled is unified with the other logical network. When unification is determined, the terminal apparatus determines whether a control terminal of a logical network newly created by unification is the terminal apparatus or a control terminal of the other logical network.

Abstract: A data communication frame is formed by a preamble portion (PREAMBLE) for demodulation and synchronization, a frame information portion (FC) containing a data type of the frame, a frame length portion (FL), and a data body portion (DATABODY) composed of more than one data packet combined together. If a request to transmit a packet is made from an upper layer, a communication apparatus 10 concurrently performs a process of calculating a frame length the frame would have if combining of the packet is performed and a process of transmitting the preamble portion and the frame information portion. The frame length depends on packets, while the preamble portion and the frame information portion do not depend on packets.

Abstract: The present invention is a communication terminal which modulates and demodulates a packet for transmission and reception based on a communication parameter for modulation and demodulation determined according to a communication-medium characteristic.

Abstract: A communication bandwidth is divided into a beacon period in which all master stations compete for transmission of a beacon packet, a first carrier sense multiple access (CSMA) period in which only authorized specific stations are allowed to compete for access, and a second CSMA period in which all stations are allowed to compete for access. The master stations exchange information with each other about a communication bandwidth being used in the first CSMA period, thereby calculating a communication bandwidth which can be used by each communication system in the first CSMA period, based on the information.

Abstract: A communication band is divided into: a beacon period in which every master station transmits a beacon packet in competition with one another; a guaranteed-band period (e.g., a TDMA period or an FDMA period) in which only a specific permitted station is allowed access; and a CSMA period in which every station is allowed access in competition with one another. Each master station exchanges information of a communication band used in the guaranteed-band period, and based on the respective information, a communication band available to the master station's own communications system in the guaranteed-band period is calculated.