Network supporting roaming, sleeping terminals

In a data communication system having a plurality of mobile transceiver units communicative with a plurality of base transceiver units,

• a network controller intercommunicative between the base transceiver units and one or more host computers for data interchange therebetween.

A radio frequency data communication system for transmission of data collected by a multiplicity of remote terminals to one or more base stations, comprising:

• the multiplicity of remote terminals selectively communicative with said one or more base stations, each of said remote t rminals selectively operable in response to transmission from one of said base stations;
• and
• each of said remote terminals independently cycling from a dormant status to an active status over predetermined time intervals when no transmission from a base station is directed to such remote terminal.

A radio frequency data communication system for transmission of data collected by a multiplicity of roaming terminals each having a radio transmitter to one or more base stations, comprising:

• the multiplicity of roaming terminals selectively communicative with said one or more base stations, each of said roaming terminals selectively operable in response to transmission from one of said base stations;
• and
• each of said roaming terminals maintaining the radio transceiver energized by battery power for a selected time interval, and after such selected time interval or after completion of a transmission occurring within such time interval, periodically turning the radio transceiver off for substantial time intervals to conserve battery power.

In a data communication system having a host computer, a plurality of intermediate bridging stations, and a plurality of mobile transceiver units, all communicative with a base station, a local area network comprising:

• said plurality of intermediate bridging stations organized into an optimal spanning tree with said base station at the root.

A method of routing information in a data communication system having a host computer, a plurality of intermediate bridges, and a plurality of mobile transceiver units, all communicative with a base station, comprising the following steps:

• organizing said data communication system into an optimal spanning tree with said base station at the root.

A method of routing information in a data communication system having a host computer, a plurality of intermediate bridges, and a plurality of mobile transceiver units, all communicative with a base station, comprising the following steps:

• (a) organizing said data communication system into an optimal spanning three with said base station at the root;
• and
• (b) said step of organizing further comprising the step of said attached bridges using a backward learning technique to learn the correct path to route data communication between said host computer and said mobile transceiver units.

A method of beginning a data exchange over and RF communication link between a polling device and a sending device wherein the polling device has an interpoll gap time, comprising the steps of:

• (a) identifying by the sending device that the RF communication link is clear throughout a period which is at least as long as the maximum possible interpoll gap time;
• and
• (b) transmitting a request for poll frame by the sending device.

A method for selecting and redundantly replacing a root device when it breaks down from among a plurality of potentially root devices, each of said potential root device having a single, assigned preset number, comprising the steps of:

• initially selecting the potential root device by identifying the lowest assigned preset number of the plurality of potential root devices;
• and
• repeating said step of selecting without considering the preset number of the current selected root device, whenever the currently selected root device breaks down.

A method used by a remote terminal for gathering and transmitting data to one or more base stations, said method comprising the steps of:

• when not gathering data, operating at a lower system clock rate so as to minimize digital noise in transmission to and reception from one or more of the base stations;
• and
• when gathering data, operating at a higher system clock rate to increase data input.

A method used by a base station having both a non-directional and a programmable, directional antenna system in a radio frequency communication system having a plurality of base stations and roaming terminals, said method comprising the steps of:

• (a) transmitting using a non-directional antenna system when communicating with one of a plurality of roaming terminals;
• and
• (b) programmably adjusting the transmission power and direction of a directional antenna system and transmitting using the directional antenna system when communicating with another of the plurality of base stations.

In a data communication system having a plurality of mobile transceiver units communicative with a plurality of base transceiver units,

• a network controller intercommunicative between the base transceiver units and one or more host computers for data interchange therebetween, and having port means providing interface at a relatively low data rate and at a relatively high data rate.