摘要:
In a multipoint communication system, first polling signals are sequentially and respectively transmitted to terminal stations on a broadcast channel from a central station, asking a request for reservation without waiting for a reply from the terminal stations. A reservation signal is transmitted on a multiple access channel from a terminal station requesting the reservation to the central station in response to the first polling signal addressed to it. A second polling signal is then transmitted on the broadcast channel in response to the reservation signal and the multiple access channel is reserved for a period of time variable in accordance with the reservation signal. A data signal is transmitted from the terminal station requesting the reservation on the reserved multiple access channel in response to the second polling signal.
摘要:
In response to call requests from a source data terminal, a source earth station establishes first logical channels between it and the source data terminal and establishes logical links from the first logical channels to destination earth stations via a communications satellite. The destination earth stations establish second logical channels from the logical links to the destination data terminals. Each earth station performs flow control on each of the respective logical channels on a per message unit basis and performs flow control on each of the logical links on the basis of per plural consecutive message units to provide high throughput on the satellite channel.
摘要:
An aspect of the invention is an information terminal device includes a widget management unit for managing execution of a widget being a monofunctional program for performing display on the display part of a display device. The widget management unit includes a policy determination unit for determining the operation policy, including operation restriction and priority, concerning a display state at the display device in the widget, and a reliability determining unit for determining the reliability representing the reliability of the widget in the widget. When the state of the movement calculated by a navigation unit becomes a preset state, the widget management unit regulates the display state of the widget according to the operation restriction and the reliability, and performs display, while preferentially displaying guidance state and positional information calculated by the navigation unit.
摘要:
A method for evaluating the performance of a wireless LAN (local area network) system having a single access point and a plurality of transmission terminals, which share the same radio channel, comprises the steps of dividing the plurality of transmission terminals into groups in accordance with radio conditions, calculating a transmission probability and a post-transmission failure probability for each group using a transmission rate, an error rate, and the number of terminals of each group, and calculating a throughput based on the transmission probability and post-transmission failure probability. A characteristic value for packet transmission delay may also be calculated based on the transmission probability and post-transmission failure probability. According to this method, the performance such as the throughput and the packet transmission delay can be evaluated in a wireless LAN system even before the wireless LAN system is constructed.
摘要:
In a radio communications system wherein a common channel is accessed from multiple terminals, any of the terminals is allowed to transmit a packet through the common channel to a base station on a random access mode when the packet received at the base station has a low error rate, and a specified one of the terminals is allowed to transmit a packet on a controlled access mode when the packet received at the base station has a high error rate.
摘要:
In a packet communication system of a multiaccess type in which a single communication medium is used commonly and divided into a plurality of channels, respective users observe states of the channels and the probability of packet transmission to respective channels is controlled in accordance with observed information, respective users are assigned parameters corresponding to respective channels and the probability of packet transmission onto the channels is controlled according to the parameters, a dummy packet is continuously transmitted for a predetermined time at in channels having low utilization factors, for data requiring immediate transmission. In a modification, a setup packet is sent for data requiring immediate transmission. All the users determine whether the received packet is the setup packet and the set the stored parameters. Accordingly, in another modification, a setup packet is transmitted for data requiring immediate transmission and a dummy packet is continuously transmitted in a channel for which the origination setting packet is successful.
摘要:
A data packet transmitted from a source data terminal is received by a destination data terminal and stored into a receive buffer from which it is withdrawn at a rate which may differ from the rate of transmission of packets from the source terminal. The destination terminal returns an acknowledgment packet in response to each data packet being withdrawn from the receive buffer. The acknowledging packet includes a flow control variable which is incremented by a unit value in response to the data packet being withdrawn from the receive buffer. The source terminal transmits one or more data packets having sequence numbers the largest of which is determined by a maximum number of outstanding data packets awaiting receipt of the acknowledging packet by the source data terminal and the flow control variable contained in the acknowledging packet.
摘要:
An aspect of the invention is an information terminal device includes a widget management unit for managing execution of a widget being a monofunctional program for performing display on the display part of a display device. The widget management unit includes a policy determination unit for determining the operation policy, including operation restriction and priority, concerning a display state at the display device in the widget, and a reliability determining unit for determining the reliability representing the reliability of the widget in the widget. When the state of the movement calculated by a navigation unit becomes a preset state, the widget management unit regulates the display state of the widget according to the operation restriction and the reliability, and performs display, while preferentially displaying guidance state and positional information calculated by the navigation unit.
摘要:
A method for evaluating the performance of a wireless LAN (local area network) system having a single access point and a plurality of transmission terminals, which share the same radio channel, comprises the steps of dividing the plurality of transmission terminals into groups in accordance with radio conditions, calculating a transmission probability and a post-transmission failure probability for each group using a transmission rate, an error rate, and the number of terminals of each group, and calculating a throughput based on the transmission probability and post-transmission failure probability. A characteristic value for packet transmission delay may also be calculated based on the transmission probability and post-transmission failure probability. According to this method, the performance such as the throughput and the packet transmission delay can be evaluated in a wireless LAN system even before the wireless LAN system is constructed.
摘要:
A method for evaluating the performance of a wireless LAN (local area network) system having a single access point and a plurality of transmission terminals, which share the same radio channel, comprises the steps of dividing the plurality of transmission terminals into groups in accordance with radio conditions, calculating a transmission probability and a post-transmission failure probability for each group using a transmission rate, an error rate, and the number of terminals of each group, and calculating a throughput based on the transmission probability and post-transmission failure probability. According to this method, the performance such as the throughput can be evaluated in a wireless LAN system even before the wireless LAN system is constructed.