US 2006/0133460 A1Published application

Method and device for fine synchronization of a digital telecommunication receiver

AssigneesTelecom Italia S.p.A., STMicroelectronics S.r.l.

InventorsDonato Ettorre, Maurizio Graziano, Bruno Melis, Andrea Finotello, Alfredo Ruscitto

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Abstract

A method for the synchronization of a digital telecommunication receiver comprises the steps of:—storing a plurality of consecutive samples E−1, B, M, 1, L+1 of an incoming spread spectrum signal in a delay line 56;—determining by interpolation between consecutive samples of the incoming spread spectrum signal, by means of a first digitally controlled interpolator 26, an interpolated early sample (e) anticipating an optimal sampling time instant;—determining by interpolation between consecutive samples of the incoming spread spectrum signal, by means of a second digitally controlled interpolator 24, an interpolated middle sample (m) corresponding to the optimal sampling time instant;—determining by interpolation between consecutive samples of the incoming spread spectrum signal, by means of a third digitally controlled interpolator 28, an interpolated late sample (1) delayed with respect to the optimal sampling time instant;—calculating an error signal ξ as the difference between the energy of the symbols computed from the interpolated early sample (e) and the interpolated late (1) sample;—extracting the sign of the error signal ξ accumulating the sign of the error signal ξ for the generation of control signals SE, SM, SL for controlling the interpolation phases of the digitally controlled interpolators used for determining the interpolated early (e), middle (m) and late (I) samples. The accumulated value has a positive saturation value of +4 and a negative saturation value of 4.

Claims21

Dependent claims

A method for fine synchronization of a digital telecommunication receiver, comprising a code tracking process for maintaining fine alignment between an incoming spread spectrum signal and a locally generated code, said method comprising:

storing a plurality of consecutive samples (E−1, E, M, L, L+1) of said incoming spread spectrum signal in a delay line (56);
determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a first (26) digitally controlled interpolator, an interpolated early sample (e) anticipating an optimal sampling time instant;
determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a second (24) digitally controlled interpolator, an interpolated middle sample (m) corresponding to said optimal sampling time instant;
determining by interpolation between consecutive samples of said incoming spread spectrum signal, by means of a third (28) digitally controlled interpolator, an interpolated late sample (l) delayed with respect to said optimal sampling time instant;
calculating an error signal (ξ) as the difference between the energy of the symbols computed from said interpolated early (e) and late (l) samples;
characterised in that said method further comprises the following steps:
extracting the sign of said error signal (ξ);
accumulating said sign of said error signal (ξ) for the generation of control signals (SE, SM, SL) for controlling the interpolation phases of said digitally controlled interpolators;
wherein the time distance between said interpolated early (e) and late (l) samples varies in relation with a first of said control signal (SM), and the time resolution used for determining by interpolation said interpolated early (e) and late (l) samples is lower than the time resolution used for determining by interpolation said middle interpolated sample (m).

6 more elements

A digital communication receiver comprising a device for maintaining fine alignment between an incoming spread spectrum signal and a locally generated code, said device comprising:

a delay line (56) for storing a plurality of consecutive samples (E−1, E, M, L, L+1) of said incoming spread spectrum signal;
a first digitally controlled interpolator (26) for determining by interpolation between consecutive samples stored in said delay line (56) an interpolated early sample (e) anticipating an optimal sampling time instant;
a second digitally controlled interpolator (24) for determining by interpolation between consecutive samples stored in said delay line (56) an interpolated middle sample (m) corresponding to said optimal sampling time instant;
a third digitally controlled interpolator (28) for determining by interpolation between consecutive samples stored in said delay line (56) an interpolated late sample (l) delayed with respect to said optimal sampling time instant;
at least a correlator (30, 32, 22) for calculating an error signal (ξ) as the difference between the energy of the symbols computed from said interpolated early (e) and late (l) samples;
characterised in that said device further comprises:
a circuit (23) for extracting the sign of said error signal (ξ);
a control signal generator (66) for accumulating said sign of said error signal (ξ) in a register for the generation of control signals (SE, SM, SL) for controlling the interpolation phases of said first (26), second (24) and third (28) digitally controlled interpolators;
wherein the time distance between said interpolated early (e) and late (l) samples varies in relation with a first of said control signals (SM), and the time resolution of said first (26) and third (28) digitally controlled interpolators is lower than the time resolution of said second (24) digitally controlled interpolator.

6 more elements

Dependencies are inferred from the claim text.