Data communications system having overlapping receiver coverage zones

• US 4,597,105 A
• Filed: 10/12/1984
• Issued: 06/24/1986
• Est. Priority Date: 11/12/1982
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Freeburg, Thomas A.
• Primary Examiner(s): Ng, Jin F.
• Application Number:
  US06/659,938
• Time in Patent Office: 620 Days
• Field of Search: 455/33, 455/54, 455/56, 179/2 EB
• US Class Current: 455/524
• CPC Class Codes: H04B 7/0851 using training sequences or error signal minimizing error signal H04B7/0854
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like

Abstract

A data communications system is described that covers a geographic area divided into a plurality of non-overlapping zones and includes a general communications controller (GCC), a plurality of channel communications modules (CCM) and associated transmitters and receivers, and a plurality of portable radios. Message signals carrying alphanumeric information are communicated between the GCC and the portable radios by way of a radio channel. Each CCM has at least one transmitter and receiver for covering at least one zone. Each CCM receiver has a coverage area overlapping the coverage area of at least two other CCM receivers and at least a predetermined minimum probability P of successful reception of a transmission from a data radio located in its coverage area, such that the joint probability P_J of successful reception of the transmission from the portable radio by at least one of the CCM receivers is expressed by the equation, P_J =1-(1-P)³. Each CCM takes a signal strength measurement every time it receives a message signal from a portable radio. The GCC gathers the signal strength measurements from the CCM receivers receiving the same message signal and computes an adjusted signal strength for each zone. The GCC then selects the zone having the largest adjusted signal strength for determining the location of the portable radio that transmitted the message signal. Whenever the GCC transmits a message signal to a portable radio, the CCM transmitter is used that covers the zone having the largest adjusted signal strength for the last transmission from that portable radio.

Claims

1. A data communications system for communicating message signals via a radio channel betgween a host computer and a plurality of data radios located anywhere in a geographical area divided into zones, said data communications system comprising:

a communications controller coupled to the host computer for communicating message signals therebetween; and

a plurality of radio channel communications modules each disposed at different locations throughout the geographical area, covering at least one zone and coupled to the communications controller for communicating message signals therebetween, each of said communications modules further including;

antenna means;

transmitting means coupled to the antenna means for transmitting message signals on the radio channel; and

receiving means coupled to the antenna means for receiving message signals from the radio channel, having a coverage area overlapping the coverage area of at least two other receiving means from other communication modules and located in the overlapping coverage area with said at least two other receiving means, said receiving means having at least a predetermmined minimum probability P of successful reception of a transmission from a data radio located in its coverage area, whereby a joint probability P_J of successful reception of the transmission from said data radio by at least one of said receiving means is expressed by the equation, P_J =1-(1-P)ⁿ, where n is the number of said receiving means covering said data radio.