Abstract: A combination-information creating unit creates combination information for determining a maximum number of combinations or a maximum frame length according to a usable radio band and a modulation method and combination possibility information for indicating that a combination of frames is possible. A frame combining unit combines a plurality of frames received from an outside access line, based on the combination information, the combination possibility information, and predetermined packet information. A frame dividing unit divides a combined frame included in a received radio signal into individual frames.

Abstract: The radio-tag reading system includes a radio-tag reader and a radio tag storing therein radio tag information. In the radio-tag reader, a radio-tag detection processor transmits via the communication unit a search signal at a predetermined time interval, and detects that the radio tag enters into the communication area of the communication unit based on a response signal to the search signal. A radio-tag information communication processor reads the radio tag information from the radio tag upon receiving the response signal from the radio tag. In the radio tag, a response processor transmits, upon receiving a signal from the radio-tag reader, a response signal in response to the signal.

Abstract: A radio tag is arranged in each of a plurality of radio tag areas. The radio tag areas can be parking lots. A radio tag reader is configured to perform radio communications with the radio tags. The radio tag reader performs radio communications with each radio tag and based on the radio communication determines whether an object, which can be a vehicle, is present in the radio tag area corresponding to the radio tag.

Abstract: A communication method for a CSMA network including a radio terminal and a base station supporting RTS/CTS, includes: the base station transmitting an RTS frame to the radio terminal during a transmission-suspend-period in which the radio terminal suspends transmission to prevent a collision of packets; the radio terminal transmitting an RTR frame to the base station after the transmission-suspend-period has elapsed; and the base station transmitting a data frame to the radio terminal in response to the RTR frame.

Abstract: Upon receiving a frame from a transmitting radio device, a propagation attenuation calculator calculates a propagation attenuation amount from information in the received frame and registers a propagation attenuation amount for each transmission rate in a table. When transmitting a frame, a transmission power controller, selects optimum transmission power to the transmission destination radio device from the table and sends the frame at the selected optimum transmission power, and detects whether there is a value smaller than the selected optimum transmission power in the optimum transmission power at a minimum transmission rate of a radio device different from a transmission destination radio device registered in the optimum transmission power table.

Abstract: A base station for a wireless LAN system has physical layers corresponding to channels, and a MAC layer. The physical layers each transmits and receives a radio signal conforming to an IEEE 802.11 standard using a corresponding channel. When transmitting, the MAC layer divides an entire data frame conforming to the standard from a head of the data frame, in accordance with a transmission rate of each physical layer, and allots the divided data frame to the physical layers so that burst times of the channels are substantially equal. When receiving, the MAC layer combines data frames received via channels through operations opposite to those performed when transmitting.

Abstract: To obtain a radio-tag reading system that can steadily make a detection area of a radio tag match with a communication area, and can start read of ID of the radio tag, which enters the communication area, at a high speed, in a condition that a plurality of radio tags enter the communication area of a radio-tag reader at a time.

Abstract: Upon receiving a frame from a transmitting radio device, a propagation attenuation calculator calculates a propagation attenuation amount from information in the received frame and registers a propagation attenuation amount for each transmission rate in a table. When transmitting a frame, a transmission power controller, selects optimum transmission power to the transmission destination radio device from the table and sends the frame at the selected optimum transmission power, and detects whether there is a value smaller than the selected optimum transmission power in the optimum transmission power at a minimum transmission rate of a radio device different from a transmission destination radio device registered in the optimum transmission power table.

Abstract: A radio tag is arranged in each of a plurality of radio tag areas. The radio tag areas can be parking lots. A radio tag reader is configured to perform radio communications with the radio tags. The radio tag reader performs radio communications with each radio tag and based on the radio communication determines whether an object, which can be a vehicle, is present in the radio tag area corresponding to the radio tag.

Abstract: A combination-information creating unit creates combination information for determining a maximum number of combinations or a maximum frame length according to a usable radio band and a modulation method and combination possibility information for indicating that a combination of frames is possible. A frame combining unit combines a plurality of frames received from an outside access line, based on the combination information, the combination possibility information, and predetermined packet information. A frame dividing unit divides a combined frame included in a received radio signal into individual frames.

Abstract: A communication method for a CSMA network including a radio terminal and a base station supporting RTS/CTS, includes: the base station transmitting and RTS frame to the radio terminal during a transmission-suspend-period in which the radio terminal suspends transmission to prevent a collision of packets; the radio terminal transmitting an RTR frame to the base station after the transmission-suspend-period has elapsed; and the base station transmitting a date frame to the radio terminal in response to the RTR frame.

Abstract: A base station for a wireless LAN system has physical layers corresponding to channels, and a MAC layer. The physical layers each transmits and receives a radio signal conforming to an IEEE 802.11 standard using a corresponding channel. When transmitting, the MAC layer divides an entire data frame conforming to the standard from a head of the data frame, in accordance with a transmission rate of each physical layer, and allots the divided data frame to the physical layers so that burst times of the channels are substantially equal. When receiving, the MAC layer combines data frames received via channels through operations opposite to those performed when transmitting.