Ncr Corporation

Inland Steel Company

Bruce T Tuch

Hans Van Driest

Michael A Masleid

Maarten Visee

Jacobus C Haartsen

In a method and apparatus for transmitting digital data packets from a station (12,14) in a wireless communication system, successive time intervals (T) are established and a packet is transmitted only if the transmission thereof does not cause a predetermined average power value (P.sub.o) to be exceeded for the current time interval. For each packet an appropriate power value is ascertained from a data base (62), in dependence on the particular destination station to which the packet is to be transmitted. For each time interval (T) a maximum energy value (I.sub.o) is decremented in accordance with the energy utilized for transmitting each packet, and a packet is transmitted only if there is sufficient energy remaining to transmit the packet during the current time interval (T).

Method and apparatus for transmitting digital data packets on a wireless

In a local area network station (12) for a wireless LAN, a threshold level circuit (62) includes a register (134) which stores a threshold value. The station receiver (42) monitors the transmission channel and provides a receive level signal indicative of the signal level received. Transmission of a data frame by the station transmitter (46) is permitted or deferred according as the receive level signal value is below or above the threshold level, regardless of whether or not the received signal derives from a transmission by a station in the receiving station's own LAN. The threshold is dynamically updated whenever the station (12) receives a data frame from its own LAN. An improved utilization of the wireless transmission channel is achieved.

Transmission control for a wireless local area network station

A wireless local area network (10) includes a plurality of stations (12) adapted to transmit and receive message packets via a distribution system (30). In a time division multiplexing embodiment the network (10) operates using successive timing frames (FR1, FR2, etc.) each consisting of three timing intervals (T1, T2, T3). During the first timing interval (T1) the distribution system (30) normally transmits synchronizing packets (HBT), to which a station (12) desiring to transmit responds by transmitting an information packet during the next second timing interval (T2). During the subsequent first timing interval (T1), the distribution system (30) retransmits the received information packet. Any transmitting station (12) which detects an information packet mismatch transmits a collision reporting code (CDT) during the next third timing interval (T3) to which the distribution system (30) responds by transmitting a collision acknowledgement code (CAKT) to all the stations (12) thereby aborting information transmission. A frequency division multiplexing embodiment is also disclosed.

Wireless information transmission system

In a digital data receiver (80) for demodulating a direct sequence spread spectrum differential phase shift keyed data signal, the signal is applied to the input transducer (140) of a SAW device (100) which has first and second output transducers (142, 144) spaced apart on the SAW substrate (130) so as to produce first and second output signals on output lines (102, 104), which are relatively delayed by a time corresponding to a symbol period. The output transducers are of identical construction and are matched to the spread spectrum code utilized in the data signal. Thus, a single SAW device (100) effects both correlation and delay. The output signals on the output lines (102, 104) are processed by a circuit including multipliers (106, 110) and a phase shifter (108) to produce output data signals representing the received data.

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Ce De Bilt, Netherlands

Bruce T Tuch