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 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: 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: Method and apparatus for controlling transmission of a data stream from a station. A QoS registration frame is received, via an access point, from the station. The QoS registration frame includes information indicating a request for transmission of a data stream from the station, and information indicating a minimum required interval and a maximum required interval for an interval which is between start points of two successive durations of a medium dedication. Each duration of the medium dedication represents a time period in which the station is permitted to transmit the data stream. A schedule for the transmission of the data stream is calculated by setting a new interval which is between the minimum required interval and the maximum required interval, when the transmission is admitted.

Abstract: A communication method of communicating among a plurality of communication apparatuses connected to a transmission channel and sharing a communication band is provided. The communication method includes: sequentially updating a slot ID with the lapse of time by a first communication apparatus; transmitting first data and a first access ID to the transmission channel by the first communication apparatus after the lapse of a first waiting time and when the slot ID is updated to a first slot ID corresponding to the first access ID; transmitting second data and a second slot ID to the transmission channel by a second communication apparatus after the lapse of a second waiting time longer than the first waiting time; and receiving the second slot ID by the first communication apparatus. In updating the slot ID, the slot ID is updated to a slot ID subsequent to the second slot ID.

Abstract: A communication apparatus communicates with another communication apparatus connected to a transmission channel and sharing a communication band. The communication apparatus includes: a receiving unit that receives, through the transmission channel, data including time information based on a transmission time when a synchronous signal is transmitted to the transmission channel from a synchronous signal transmitting apparatus at a given cycle, the synchronous signal for synchronizing a plurality of communication apparatuses; a transmitting unit that transmits data to the transmission channel; and a transmission control unit that estimates a synchronous signal non-existing period in which there is no synchronous signal on the transmission channel on the basis of the time information received by the receiving unit and the given cycle, and controls the transmitting unit to transmit data within the estimated synchronous signal non-existing period.

Abstract: Provides a terminal for performing multiple access transmission suitable to a transmission path having varied characteristics. The terminal (100) includes a transmission/reception section (201), a control unit (204), a transfer management section (206), and an external interface section (203). The terminal (100) refers to an IGMP (MLD) message received by the transmission/reception section (201) to classify a transmitter host and a relay device of this message based on the characteristic of the transmission path, and performs a multiple access transmission of a multicast packet in a form suitable to the characteristic of the respective transmission path.

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: 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: A communication apparatus for communicating by commonly sharing a transmission channel with another communication apparatus which performs a data transmission, comprising: a transmitting unit which transmits first data at first timing and second data at second timing subsequent to the first timing to the transmission channel; and an information adding unit which adds time slot information to the first data, the time slot information indicating a time slot during which the second data is transmitted prior to the data transmission performed by the other communication apparatus.

Abstract: An efficient medium dedication schedule is generated. The schedule gives wireless medium an ability to concurrently serve real-time and non real-time application and still be able to maintain the Quality of Service as requested by the real-time application. Furthermore, QoS registration request is delivered in a time bound manner and a time slot is chosen for transmission during controlled contention phase that give lesser collision and higher throughput.

Abstract: Terminal devices F and G store statistical information related to interference from an external communication system, and notify the stored statistical information to a master station E. The master station E determines the terminal device G as a candidate station for a master station capability handover destination based on collected statistical information. The master station E requests to hand over a master station capability to the terminal device G. If it is determined that the terminal device G accepts handover of the master station capability, the terminal device G starts to act as the master station.

Abstract: A communication method in a communication system which includes a master apparatus and plural slave apparatuses including at least first, second and third slave apparatuses, that are connected to communication medium and are associated with plural cyclic slots including at least first and second slots for triggering data transmission after a latency time, wherein data transmissions of the first and the second slave apparatuses are triggered by the first slot; and data transmission of the third slave apparatus is triggered by the second slot, the method including: sensing the communication medium by the master apparatus; and modifying, by the master apparatus, the first slave apparatus so as to trigger the data transmission of the first slave apparatus by a third slot which differs from the first and the second slots when the data transmission of the first slave apparatus triggered by the first slot is sensed in the sensing process.

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: Terminal devices F and G store statistical information related to interference from an external communication system, and notify the stored statistical information to a master station E. The master station E determines the terminal device G as a candidate station for a master station capability handover destination based on collected statistical information. The master station E requests to hand over a master station capability to the terminal device G. If it is determined that the terminal device G accepts handover of the master station capability, the terminal device G starts to act as the master station.

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: 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 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 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.