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A hierarchical communication system, arranged in a spanning tree configuration, is described in which wired and wireless communication networks exhibiting substantially different characteristics are employed in an overall scheme to link portable or mobile computing devices. Copies of data, program c

A hierarchical communication system, arranged in a spanning tree configuration, is described in which wired and wireless communication networks exhibiting substantially different characteristics are employed in an overall scheme to link portable or mobile computing devices. Copies of data, program code and processing resources are migrated from their source toward requesting destinations based on request frequency, communication link costs and available local storage and/or processing resources. Each appropriately configured network device acts as an active participant in network migration. In addition, portable two-dimensional (2-D) code reading terminals are configured to wirelessly communicate compressed 2-D images toward stationary access servers that identify the code image through decoding and through comparison with a database of images that have previously been decoded and stored.

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We claim: 1. A method for reducing interference, the method comprising steps of: transmitting a message from a first communication device using a first communication protocol, the message being formatted to inform a second communication device to refrain from communicating with the first communicat

We claim: 1. A method for reducing interference, the method comprising steps of: transmitting a message from a first communication device using a first communication protocol, the message being formatted to inform a second communication device to refrain from communicating with the first communication device using the first communication protocol during a specified time period to avoid colliding with another communications signal of a second communication protocol. 2. The method of claim 1, wherein the first communication device communicates in a first network and a second network. 3. The method of claim 2, wherein the second communication device communicates in at least the first network, wherein signals from the second communication device that are intended for the first network are delayed during the specified time. 4. The method of claim 2, wherein the first network operates according to the first communication protocol and the second network operates according to the second communication protocol. 5. The method of claim 1, wherein the method comprises transmitting data, wherein transmitting the message occurs before transmitting data, thereby minimizing collisions during data transmission and reducing inefficiencies due to packet loss and retransmission time. 6. The method of claim 1, wherein the method comprises determining a number of slots allocated for communication by the second communication device, wherein transmitting the message occurs after determining the number of slots. 7. The method of claim 6, wherein determining the number of slots is responsive to network channel loading conditions. 8. The method of claim 6, wherein collision detection is used in a slot allocation algorithm for determining addition or deletion of slots. 9. A system in a first wireless communication device for controlling communication among a plurality of wireless communication devices which communicate in one or more networks, the system comprising: a memory device for storing a plurality of communication protocols; and a control processor for selecting one of the plurality of communication protocols, wherein the control processor transmits a message to a second wireless communication device to reduce the probability of collision among the plurality of communication protocols. 10. The system of claim 9, wherein the selection of the communication protocol is on a priority basis. 11. The system of claim 9, wherein the message from the control processor causes the second wireless communication device to enter a low power consumption mode if the second wireless communication device is not actively communicating on any of the one or more networks. 12. The system of claim 9, wherein the selection is communicated by transmitting a message from the first wireless communication device to the second wireless communication device, wherein the message controls transmission by the second wireless communication device. 13. The system of claim 12, wherein the message enables a sleep mode to be established in the second wireless communication device, thereby avoiding collisions between signals intended for a first network and signals intended for a second network. 14. The system of claim 13, wherein sleep mode lasts for a predetermined number of time intervals. 15. The system of claim 12, wherein the message informs the second communication device to refrain from communicating during a specified time period to avoid colliding with another communications signal. 16. The system of claim 12, wherein transmitting the message occurs before the first wireless communications device transmits data, thereby minimizing collisions during data transmission and reducing inefficiencies due to packet loss and retransmission time. 17. The system of claim 12, wherein transmitting the message occurs after the control processor determines a number of slots allocated for communication by the second wireless communication device. 18. The system of claim 17, wherein determining the number of slots is responsive to a network channel loading condition. 19. The system of claim 17, wherein the control processor uses a slot allocation algorithm with collision detection for determining addition or deletion of slots. 20. A system for reducing interference, the system comprising: one or more circuits for transmitting a message from a first communication device using a first communication protocol, the message being formatted to inform a second communication device to refrain from communicating with the first communication device using the first communication protocol during a specified time period to avoid colliding with another communications signal of a second communication protocol.