Method permitting increased frequency re-use in a communication network, by recovery of transmitted information from multiple cochannel signals

• US 6,697,633 B1
• Filed: 01/18/2000
• Issued: 02/24/2004
• Est. Priority Date: 06/02/1995
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Dogan, Mithat Can, Stearns, Stephen Deane
• Primary Examiner(s): Nguyen, Lee
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US09/484,724
• Time in Patent Office: 1,498 Days
• Field of Search: 455/509, 455/450, 455/452, 455/453, 455/454, 455/561, 455/562
• US Class Current: 455/509
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04L 25/03993 Noise whitening

Abstract

A method for use in a communication network having multiple users and limited bandwidth, wherein up to N users are allocated to the same frequency band at the same time, and the method provides for processing signals received at an M-element antenna array, using a cumulant-based signal recovery system to separate and recover the signals transmitted by the respective users.

Claims

1. For use in a communication network having multiple users and limited bandwidth, a method for increasing the capacity of the communication system, comprising the steps of:

allocating up to N users the same bandwidth sharing parameter, such that the up to N users share the same frequency at the same time;

receiving signals from up to N users at an M-element antenna array; and

processing the received signals transmitted by the respective users, wherein the step of processing separates and recovers the signals transmitted by the respective users directly from the received signals and without use of array manifold data.

2. A method as defined in claim 1, wherein the processing step includes:

generating for each user from whom signals are received and estimated generalized steering vector (EGSV) that results in optimization of a utility function that depends on fourth or higher even-order cumulants derived from the received signals.

3. A method as defined in claim 2, wherein:

the receiving step includes receiving signals over multiple paths for at least one of the users;

the EGSV for a user is indicative of a combination of signals received at the antenna array from the same user; and

the processing step inherently combines coherent multipath signal components received from the same user.