Class of low cross correlation palindromic synchronization sequences for time tracking in synchronous multiple access communication systems

• US 5,909,447 A
• Filed: 03/07/1997
• Issued: 06/01/1999
• Est. Priority Date: 10/29/1996
• Status: Expired due to Fees

• Current Assignee: Alcatel USA Sourcing L.P. (Nokia Corporation)
• Original Assignee: Stanford Telecommunications, Inc. (Nokia Corporation)
• Inventors: Cox, Timothy F., Natali, Francis D.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US08/813,091
• Time in Patent Office: 816 Days
• Field of Search: 370/503, 370/507, 370/508, 370/509, 370/514, 370/515, 370/519
• US Class Current: 370/508
• CPC Class Codes: H04L 7/041 using special codes as synchronising signal

Abstract

A star configured multiple access radio communication system wherein a hub station communicates, in time division multiplex mode, with a plurality of remote subscriber stations by a forward link signal path and the remote subscriber stations communicate with the hub on a return link signal path and wherein all received return link signals are time synchronous, and all signals possess the same time division multiplex structure in which a portion of the signal is dedicated to time synchronization. Each remote subscriber station has a synchronization burst sequence generator, each generated burst sequence is constructed such that the time tracking and synchronization process of each return link is relatively unaffected by all other remote stations. At the hub station there is a delay discrimi-nator for each remote subscriber, each delay discriminator includes a first and a second channel. The first channel has a one symbol delay device, a matched filter, and a squaring circuit. The second channel has a matched filter and a squaring circuit. A summing circuit sums the outputs of the squaring circuits, and an output sampler sample the incoming signals at an offset of half a symbol period with respect to the peak of the first matched filter.

Claims

1. In a star configured multiple access radio communication system wherein a hub station communicates, in time division multiplex mode, with a plurality of remote subscriber stations by means of a forward link signal path and the remote subscriber stations communicate with the hub on a return link signal path and wherein all received return link signals are time synchronous, and all signals possess the same time division multiplex structure in which a portion of the signal is dedicated to time synchronization, the improvement comprising:

at each remote subscriber station, a synchronization burst sequence generator, each burst sequence generator assuming that the time tracking and synchronization process of each return link is relatively unaffected by all other remote stations, due to the nature of the synchronization burst sequences,

and at said hub station a delay discriminator for each remote subscriber, each said delay discriminator including a first and a second channel,

said first channel having a one symbol delay means, a matched filter, and a squaring circuit, said second channel having a matched filter and a squaring circuit,

means summing the outputs of said squaring circuits, and

an output sampler for sampling the incoming signals at an offset of half a symbol period with respect to the peak of said first matched filter.

2. In a star configured multiple access radio communication system wherein a hub station communicates, in time division multiplex mode, with a plurality of remote subscriber stations by means of a forward link signal path and each said remote subscriber station communicates with said hub station on a respective return link signal path and wherein all received return link signals are time synchronous, and all signals possess the same time division multiplex structure in which a synchronization burst portion of the signal is dedicated to the time synchronization, the improvement comprising:

at each remote subscriber station, a synchronization burst sequence generator, each burst sequence generator generating a palindromic synchronization burst sequence, and

at said hub station a delay discriminator for each remote subscriber.

3. The system of claim 2 wherein each said delay discriminator includes a first and a second channel,

said first channel having a one symbol delay means, a matched filter, and a squaring circuit, said second channel having a matched filter and a squaring circuit,

means summing the outputs of said squaring circuits, and

an output sampler for sampling the incoming signals at an offset of half a symbol period with respect to the peak of said first matched filter.