Method for symbol sampling in a high time delay spread interference environment

a high-time delay spread and interference environment technology, applied in the field of radio communications, can solve the problems of affecting the initial synchronization and call start time, the bit-error rate (ber) of the receive radio in the site overlap area, and the conventional synchronization method takes a relatively long time to converge to the optimal synchronization time,

Active Publication Date: 2015-03-05
HARRIS CORP
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AI Technical Summary

Problems solved by technology

The delay spread is known to degrade the bit-error-rate (BER) of receive radios in site overlap areas.
The symbols contained in the synchronization field do not represent user data and therefore comprise overhead in the communication system.
Still, due to the limited number of synchronization symbols, conventional synchronization methods take a relatively long time to converge to the optimal synchronization time when operating in a high delay spread environment.
This slow synchronization process can severely degrade the time required to establish initial synchronization and call start.

Method used

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  • Method for symbol sampling in a high time delay spread interference environment
  • Method for symbol sampling in a high time delay spread interference environment
  • Method for symbol sampling in a high time delay spread interference environment

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Embodiment Construction

[0029]The invention is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operation are not shown in detail to avoid obscuring the invention. The invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and / or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the in...

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Abstract

Symbol sampling in a high time delay spread interference environment includes acquiring (602) a time varying baseband waveform. The waveform has a signal amplitude that varies between one of a plurality of symbol states. The waveform is sampled (603) at a rate of m times the symbol rate. During an evaluation time, an error value is calculated (604, 606) for each of m data sample positions. Each of the error values comprises an average distance between the measured value of the waveform as indicated by the data sample and a closest known symbol value. The error values are used to create an error surface. Thereafter, the error surface is modeled as a quadratic and an optimal sample time is determined (608, 610, 612) based on finding the time location where the quadratic surface is minimum. A sinc interpolator is then used to resample the data.

Description

BACKGROUND OF THE INVENTION[0001]1. Statement of the Technical Field[0002]The inventive arrangements relate to radio communications and more particularly to improvements in symbol sampling in communications environments where a significant amount of delay spread exists.[0003]2. Description of the Related Art[0004]Simulcast systems create delay spread at receive sites that is proportional to site spacing. The delay spread is known to degrade the bit-error-rate (BER) of receive radios in site overlap areas. Coverage area of a simulcast system can be improved by reducing the adverse effects that delay spread has upon BER. When the coverage area is improved in this way, the number of simulcast transmitter sites can be reduced, thereby lowering overall infrastructure costs.[0005]Symbol synchronization is used to estimate the optimal time for sampling each symbol in a received signal. Improved symbol synchronization is a key factor for purposes of reducing BER. Conventional synchronizatio...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04L7/00
CPCH04L7/0029H04L7/0062
Inventor HARTLESS, MAC L.TAYLOR, RICHARD D.WYNN, STEVE R.
Owner HARRIS CORP
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