Radio frequency communication network having adaptive communication parameters

Abstract

Improved apparatus for a radio communication network having a multiplicity of mobile transceiver units selectively in communication with a plurality of base transceiver units which communicate with one or two host computers for storage and manipulation of data collected by bar code scanners or other collection means associated with the mobile transceiver units. The radio network is adaptive in that in order to compensate for the wide range of operating conditions a set of variable network parameters are exchanged between transceivers in the network. These parameters define optimized communication on the network under current network conditions. Examples of such parameters include: the length and frequency of the spreading code in direct-sequence spread spectrum communications; the hop frame length, coding, and interleaving in frequency-hopping spread spectrum communications; the method of source encoding used; and the data packet size in a network using data segmentation. The invention is preferably to be applicable as an upgrade of an existing data capture system wherein a large number of hand-held transceiver units operate over an extensive area to gather data in various places, requiring the use of multiple base stations. In a variety of such installations such as warehouse facilities, distribution centers, and retail establishments, it may be advantageous to utilize not only multiple bases capable of communication with a single host, but with multiple hosts as well.

What is claimed is:  
     
         1 . A data communication system for collecting and communicating data using RF data signal transmission, comprising: 
 a first terminal having transmission and reception capability from which communication is desired;    a second terminal having transmission and reception capability to which communication from said first terminal is desired;    said first and second terminals being responsive to an operating parameter for determining and maintaining the operation of transmission and reception;    means within said second terminal that is responsive to transmissions received from said first terminal for evaluating the current data communication system;    means responsive to said evaluation means for determining whether a change in the operating parameter should be made; and    means within said first terminal that is responsive to said determination means for changing the operating parameter.    
     
     
         2 . The data communication system of    claim 1    wherein said determination means bases its inquiry on the percentage of RF signals which have been successfully received.  
     
     
         3 . The data communication system of    claim 1    wherein said evaluation means bases its evaluation on the signal strength of the received RF signal.  
     
     
         4 . The data communication system of    claim 1    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means basing its determination on the signal produced by said measuring circuit.  
     
     
         5 . The data communication system of    claim 4    wherein said evaluation means utilizes a threshold for making its evaluation.  
     
     
         6 . The data communication system of    claim 4    wherein said determination means utilizes a threshold window for making its determination.  
     
     
         7 . The data communication system of    claim 1    wherein said operating parameter indicates the size of data segments to be transmitted.  
     
     
         8 . The data communication system of    claim 7    wherein said determination means bases its determination on the percentage of RF signals that have been successfully received.  
     
     
         9 . The data communication system of    claim 7    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         10 . The data communication system of    claim 1    having spread spectrum communication capability wherein said operating parameter indicates the length of the spreading code for spread spectrum communication.  
     
     
         11 . The data communication system of    claim 10    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         12 . The data communication system of    claim 10    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         13 . The data communication system of    claim 1    having spread spectrum communication capability wherein said operating parameter indicates the chip clock rate of the spreading code for direct-sequence spread spectrum communication.  
     
     
         14 . The data communication system of    claim 14    wherein said determination means bases its determination on the percentage of RF signals that have been successfully received.  
     
     
         15 . The data communication system of    claim 14    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         16 . The data communication system of    claim 1    having frequency-hopping spread spectrum communication capability wherein said operating parameter defines characteristics of frequency-hopping transmissions.  
     
     
         17 . The data communication system of    claim 16    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         18 . The data communication system of    claim 16    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         19 . The data communication system of    claim 1    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates the hopping rate.  
     
     
         20 . The data communication system of    claim 19    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         21 . The data communication system of    claim 19    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         22 . The data communication system of    claim 1    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates whether coding is to be used, and, if so, the type of coding.  
     
     
         23 . The data communication system of    claim 22    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         24 . The data communication system of    claim 22    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         25 . The data communication system of    claim 1    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates whether interleaving is to be used, and, if so, the type of interleaving.  
     
     
         26 . The data communication system of    claim 22    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         27 . The data communication system of    claim 22    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         28 . The data communication system of    claim 1    having RF source encoding wherein said operating parameter indicates the type of source encoding to be used in maintaining RF communication.  
     
     
         29 . The data communication system of    claim 28    wherein said evaluation means bases its evaluation on the percentage of RF signals that have been successfully received.  
     
     
         30 . The data communication system of    claim 28    wherein said evaluation means comprises a measuring circuit that produces a signal indicative of the signal strength of received RF signals, and said determination means bases its determination on the signal produced by said measuring circuit.  
     
     
         31 . A data communication system for collecting and communicating data in the form of RF signals comprising: 
 a plurality of RF transceivers that store and modify a variable operating parameter;    each of said transceivers controlling the operation of transmission and reception based on the stored of parameter;    means within said transceivers for evaluating the stored parameter based on each transmission received;    means responsive to said evaluation means for determining whether the operating parameter should be modified; and    said plurality of RF transceivers responding to said determination means by storing modified operating parameters.    
     
     
         32 . The data communication system of    claim 31    wherein said operating parameter indicates the size of data segments to be transmitted.  
     
     
         33 . The data communication system of    claim 31    having spread spectrum communication capability wherein said operating parameter indicates the length of the spreading code for spread spectrum communication.  
     
     
         34 . The data communication system of    claim 31    having spread spectrum communication capability wherein said operating parameter indicates the chip clock rate of the spreading code for direct-sequence spread spectrum communication.  
     
     
         35 . The data communication system of    claim 31    having frequency-hopping spread spectrum communication capability wherein said operating parameter defines characteristics of frequency-hopping transmissions.  
     
     
         36 . The data communication system of    claim 31    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates the hopping rate.  
     
     
         37 . The data communication system of    claim 31    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates whether coding is to be used, and, if so, the type of coding.  
     
     
         38 . The data communication system of    claim 31    having frequency-hopping spread spectrum communication capability wherein said operating parameter indicates whether interleaving is to be used, and, if so, the type of interleaving.  
     
     
         39 . The data communication system of    claim 31    having RF source encoding wherein said operating parameter indicates the type of source encoding to be used in maintaining RF communication.  
     
     
         40 . The data communication system of    claim 31    further comprising: 
 means within said transceivers being responsive to a series of failed communication exchanges for replacing said stored operating parameter with a system default value.  
 
     
     
         41 . A data communication system for collecting and communicating data using RF data signal transmission, comprising: 
 a first terminal having transmission and reception capability from which communication is desired;    a second terminal having transmission and reception capability to which communication from said first terminal is desired;    said first and second terminals being responsive to an operating parameter for determining and maintaining the operation of transmission and reception;    means within said second terminal being responsive to transmissions received from said first terminal for evaluating the performance of the transmission;    means within said second terminal for determining whether a change in the operating parameter is needed, and, if so, for transmitting a request for change signal to said first terminal;    said first terminal responding to a received request for change signal by transmitting an acknowledge signal then modifying and storing the operating parameter; and    means at said second terminal responsive to the acknowledge signal for modifying and storing the operating parameter.    
     
     
         42 . The data communication system of    claim 41    further comprising: 
 means at said terminals being responsive to a series of failed communication exchanges for replacing said stored operating parameter with a system default value.  
 
     
     
         43 . The data communication system of    claim 42    wherein said operating parameter indicates the size of data segments to be transmitted.  
     
     
         44 . The data communication system of    claim 42    having spread spectrum communication capability wherein said operating parameter indicates the length of the spreading code for spread spectrum communication.  
     
     
         45 . The data communication system of    claim 42    having spread spectrum communication capability wherein said operating parameter indicates the chip clock rate of the spreading code for direct-sequence spread spectrum communication.  
     
     
         46 . The data communication system of    claim 42    having RF source encoding wherein said operating parameter indicates the type of source encoding to be used in maintaining RF communication.  
     
     
         47 . The data communication system of    claim 42    having frequency-hopping spread spectrum communication capability wherein said operating parameter defines characteristics of frequency-hopping transmissions.