position determination in an integrated cellular communications system

• US 5,612,703 A
• Filed: 05/19/1995
• Issued: 03/18/1997
• Est. Priority Date: 03/19/1990
• Status: Expired due to Fees

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: Celsat America, Inc.
• Inventors: Mallinckrodt, Albert J.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/444,574
• Time in Patent Office: 669 Days
• Field of Search: 342/387, 342/457, 342/458, 379/59, 455/54.1, 455/54.2, 375/205
• US Class Current: 342/457
• CPC Class Codes: H04B 7/18517 Transmission equipment in earth stations
• CPC Class Codes: H04B 7/18532 Arrangements for managing transmission, i.e. for transporting data or a signalling message
• CPC Class Codes: H04B 7/18534 for enhancing link reliablility, e.g. satellites diversity
• CPC Class Codes: H04B 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00
• CPC Class Codes: H04B 7/18558 Arrangements for managing communications, i.e. for setting up, maintaining or releasing a call between stations
• CPC Class Codes: H04B 7/2041 Spot beam multiple access
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 5/02 Channels characterised by the type of signal
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

A cellular communications system is provided having both surface and satellite nodes which are fully integrated for providing service over large areas. Position means are included for determining the position of a selected user unit within the cells by providing a timing signal to the selected user unit from at least one node, providing a timing response signal from the selected user unit in response to each timing signal, receiving the timing response signal by at least one node, measuring the response time of the user unit to the timing signal based on receipt of the timing response signal, and determining the position of the user unit based on the round trip time of transmission of the timing signal and receipt of the timing response signal. Preferably, the invention provides position determination in a cellular communications system using code division multiple access (CDMA) employing forward error correction coding (FECC) and spread spectrum waveforms.

Claims

1. A cellular communications system comprising:

at least one node positioned so to establish a set of cells, each node including means for transmitting and receiving different predetermined sets of code division multiple access coded, digitally modulated spread spectrum waveforms;

a plurality of user units within the cells, each user unit including means for communicating with at least one of said nodes and being operatively responsive to a predetermined one of the sets of code division multiple access coded waveforms to thereby establish selective communication with at least one of said nodes; and

position determination means for determining the position of a selected user unit by providing a timing signal carried by one of the sets of code division multiple access coded waveforms to the user unit from one or more nodes, providing a timing response signal carried by one of the sets of code division multiple access coded waveforms from the selected user unit in response to each timing signal, receiving the timing response signal by at least one node, measuring the response time of the user unit to each timing signal, and determining the position of the user unit based on such measurements.

2. In the operation of a cellular communications system having a plurality of user units and at least one cellular node so as to establish at least one cell, each node and user unit including means for transmitting and receiving different predetermined sets of code division multiple access coded digitally modulated spread spectrum waveforms, the method for determining the position of a selected user unit comprising:

a) providing a timing signal carried by one of the sets of code division multiple access coded waveforms to the selected user unit from at least one node;

b) providing a timing response signal carried by one of the sets of code division multiple access coded waveforms from the selected user unit in response to the timing signal;

c) receiving the timing response signal by at least one node;

d) measuring the response time of the user unit to the timing signal based on receipt of the timing response signal; and

e) determining the position of the user unit based on the round trip time of transmission of the timing signal and receipt of the timing response signal.