Symbol Technologies, LLC

Other

LaRoy Tymes

John W Kramer

Gregory B Ennis

Fredric Heiman

A method and data structure for transmitting data in a networked system having a shared transmission medium that includes generating a plurality of virtual packets each containing information for delivery to at least one selected terminal in the networked system via the shared medium and generating a map field having control information for controlling the delivery of the virtual packets. The method and data structure also include forming a physical packet for transmission across the shared transmission medium, the physical packet including a control field and the plurality of virtual packets such that overhead associated with the control field and medium access is amortized over the plurality of virtual packets.

Data structures with amortized control overhead and methods and networks using the same

A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate an exchange with the remote units, but instead send data to the remote units only as part of the exchange. To alert a remote unit when a message is waiting at a base station to be sent to a particular unit, some of the acknowledge (base-to-remote) packets sent by the base station may contain an identification such as a list of all remote units (identified by ID number) which have messages waiting. Alternatively, a bit map can be used to identify these remotes. These base-to-remote packets with the identification of remotes with messages waiting are called 'announcements.' Each remote unit (if not engaged in regular exchanges for a time interval) periodically listens (activates its receiver) to receive an announcement packet containing such a list or bit map and decodes this announcement to see if it has a message waiting. If so, this remote unit then sends a transmit packet so the base can send the waiting message in an acknowledge packet.

Protocol for packet data communication system

A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. A frequency-hopping transmission method is used for the RF link. The remote units and base stations are all synchronized to a repeating pseudo-random sequence of frequencies in a band (902-928 MHz) which allows this type of transmission. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange. The reply messages from the base stations to the remotes contain synchronizing information to maintain coherence with the pseudo-random sequence.

Packet data communication system

A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.

A data processing system has a host computer which is coupled to a light source. The light source illuminates an area surrounding said light source and also transmits data sent to it by the host computer by modulating the light that it generates. A multiplicity of small data processing devices use photodiodes to receive both power and data from the light source. The photodiodes generate an electrical voltage which provide power to a microprocessor. A demodulator, coupled to that electrical voltage, detects peaks in the voltage which are interpreted by the microprocessor so as to regenerate the data transmitted by the light source. The microprocessor then interprets the received data and performs a task or command specified by the received data. In one embodiment, the microprocessor is coupled to an LCD display and the received data specifies what data is to be displayed on the LCD display.

System for converting a received modulated light into both power for the

Packet data communication network

A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central compuer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exchange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.

Signal quality measure in packet data communication

A packet data transmission system is used to link a number of remote hand-held data-gathering units such as bar code readers to a central computer which maintains a database management system. Data packets are sent from the remote units by an RF link to intermediate base stations, then sent by the base stations to the central computer by a serial link. Direct sequence spread spectrum modulation is used for the RF link. The remote hand-held units initiate an exhange using RF transmission to and from the base stations, receiving only during a rigid time window following a transmission from the remote unit. The base stations cannot initiate communication to the remote units, but instead send data to the remote units only as part of the exchange.

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Palo Alto, CA, United States of America

LaRoy Tymes