Method and system for adapting an effective spreading sequence in a communication system using direct sequence spreading

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel, the determination unit configured to:
• determine a value of a phase shift factor α that maximizes the expression:
• Re
• (
• ∑
• m
• 
• 
• j
• 
• 
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• 
• C
• ss
• 
• (
• m
• )
• 
• C
• hh
• *
• 
• (
• m
• )
• )
• wherein:
• Re identifies real part;
• j is an imaginary unit;
• m is an index;
• M is number of phases;
• * identifies a complex conjugate;
• Css(m) is a value of an aperiodic autocorrelation of the effective spreading sequence;
• and
• Chh(m) is a value of an aperiodic autocorrelation of an impulse response of the communication channel;
• determine the plurality of linearly related phases in accordance with the phase shift factor α;
• and
• apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to despread a received signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel, the determination unit configured to:
• calculate for each of a plurality of indexes m a corresponding value of an aperiodic autocorrelation of an impulse response of the communication channel Chh(m);
• determine an index mmax>0 for which a magnitude of the value Chh(m) attains maximum;
• determine a value of an aperiodic autocorrelation of an effective spreading sequence Css(mmax);
• determine the plurality of linearly related phases in accordance with the Chh(mmax) and the Css(mmax);
• and
• apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to despread a received signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel, the determination unit configured to:
• determine indexes m1 and m2 for the largest and the second largest magnitudes of an impulse response of the communication channel h(m);
• calculate an aperiodic autocorrelation of the impulse response of the communication channel Chh(mmax), wherein mmax=m1−m2;
• calculate an aperiodic autocorrelation of an effective spreading sequence Css(mmax);
• and
• determine the plurality of linearly related phases in accordance with the Chh(mmax) and the Css(mmax);
• wherein the determination unit is further configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to despread a received signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel, the determination unit configured to:
• determine indexes m1 and m2 for the largest and the second largest magnitudes of an impulse response of the communication channel h(m);
• determine a phase of Chh(mmax), wherein mmax=m1−m2;
• determine a phase of Css(mmax);
• determine the plurality of linearly related phases in accordance with the phases of Chh(mmax) and the Css(mmax);
• and
• apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to despread a received signal.

An apparatus for adapting an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel and apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence by evaluating for each index m an equation:
• s′(m)=ejθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is number of phases,
• and wherein the determination unit is further configured to use the adapted spreading sequence to despread a received signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a channel estimation unit configured to determine a state of a communication channel;
• and
• a determination unit configured to determine a plurality of linearly related phases in accordance with the state of the communication channel and apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence by evaluating for each index m an equation:
• s′(m)=e−jθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is the number of phases,
• and wherein the adapted spreading sequence is used to despread a received signal.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel which includes:
• determining an operating environment of the communication system;
• selecting a pre-determined model for the state of the communication channel in accordance with said determined operating environment;
• determining parameters of the pre-determined model in accordance with the state of the communication channel;
• and
• determining the state of the communication channel from the parameters and the pre-determined model;
• determining a plurality of linearly related phases in accordance with the state of the communication channel;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel, including:
• determining a value of a phase shift factor α that maximizes the expression:
• Re
• (
• ∑
• m
• 
• 
• j
• 
• 
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• 
• C
• ss
• 
• (
• m
• )
• ·
• C
• hh
• *
• 
• (
• m
• )
• )
• wherein:
• Re identifies real part;
• j is an imaginary unit;
• m is an index;
• M is number of phases;
• * identifies a complex conjugate;
• Css(m) is a value of an aperiodic autocorrelation of the effective spreading sequence;
• and
• Chh(m) is a value of an aperiodic autocorrelation of an impulse response of the communication channel;
• and
• determining the plurality of linearly related phases in accordance with the phase shift factor α;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel, the means including:
• calculating for each of a plurality of indexes m a corresponding value of an aperiodic autocorrelation of an impulse response of the communication channel Chh(m);
• determining an index mmax>0 for which a magnitude of the value Chh(m) attains maximum;
• determining a value of an aperiodic autocorrelation of an effective spreading sequence Css(mmax);
• and
• determining the plurality of linearly related phases in accordance with the Chh(mmax) and the Css(mmax);
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel, including:
• determining indexes m1 and m2 for the largest and the second largest magnitudes of an impulse response of the communication channel h(m);
• calculating an aperiodic autocorrelation of the impulse response of the communication channel Chh(mmax), wherein mmax=m1−m2;
• calculating an aperiodic autocorrelation of an effective spreading sequence Css(mmax);
• and
• determining the plurality of linearly related phases in accordance with the Chh(mmax) and the Css(mmax);
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel, including:
• determining indexes m1 and m2 for the largest and the second largest magnitudes of an impulse response of the communication channel h(m);
• determining a phase of Chh(mmax), wherein mmax=m1−m2;
• determining a phase of Css(mmax);
• and
• determining the plurality of linearly related phases in accordance with the phases of Chh(mmax) and the Css(mmax);
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel;
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence, the means including means for evaluating for each index m an equation:
• s′(m)=ejθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is number of phases.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, comprising:

• determining a state of a communication channel;
• determining a plurality of linearly related phases in accordance with the state of the communication channel;
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence, the means including means for evaluating for each index m an equation:
• s′(m)=e−jθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is the number of phases.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a feedback receiver configured to receive a feedback signal comprising a phase factor α and information enabling determination of a plurality of linearly related phases;
• a device configured to determine the plurality of linearly related phases in accordance with the feedback by evaluating for each index m an equation:
• θ
• 
• (
• m
• )
• =
• 2
• 
• 
• π
• 
• 
• α
• 
• 
• m
• M
• ;
• wherein:
• M is number of phases;
• and
• a multiplier configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to spread a transmit signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a feedback receiver configured to receive a feedback signal comprising information enabling determination of a plurality of linearly related phases wherein the feedback signal comprises a pre-determined model characterizing the communication channel and at least one parameter of the pre-determined model;
• a device configured to determine the plurality of linearly related phases in accordance with the feedback;
• and
• a multiplier configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to spread a transmit signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a feedback receiver configured to receive a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• a device configured to determine the plurality of linearly related phases in accordance with the feedback, the device configured to:
• determine an impulse response of the communication channel h(m) in accordance with the pre-determined model and the parameters;
• determine indexes m1 and m2 for the largest and the second largest magnitudes of the impulse response of the communication channel h(m);
• determine a phase of Chh(mmax), wherein mmax=m1−m2;
• determine a phase of Css(mmax);
• and
• determine the plurality of linearly related phases in accordance with the phases of Chh(mmax) and the Css(mmax);
• and
• a multiplier configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to spread a transmit signal.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a feedback receiver configured to receive a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• a device configured to determine the plurality of linearly related phases in accordance with the feedback;
• and
• a multiplier configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to spread a transmit signal by evaluating for each index m an equation:
• s′(m)=ejθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• πα
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is number of phases.

An apparatus configured to adapt an effective spreading sequence in a communication system, comprising:

• a feedback receiver configured to receive a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• an apparatus configured to determine the plurality of linearly related phases in accordance with the feedback;
• and
• a multiplier configured to apply at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence to generate an adapted spreading sequence, wherein the adapted spreading sequence is used to spread a transmit signal by
• evaluating for each index m an equation:
• s′(m)=e−jθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• πα
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is the number of phases.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• receiving a feedback signal comprising information enabling determination of a plurality of linearly related phases, wherein the feedback signal comprises a phase factor α;
• determining the plurality of linearly related phases in accordance with the feedback, including
• evaluating for each index m an equation:
• θ
• 
• (
• m
• )
• =
• 2
• 
• πα
• 
• 
• m
• M
• ;
• wherein:
• M is number of phases;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• receiving a feedback signal comprising information enabling determination of a plurality of linearly related phases wherein the feedback signal comprises a pre-determined model characterizing the communication channel;
• and at least one parameter of the pre-determined model;
• determining the plurality of linearly related phases in accordance with the feedback;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• receiving a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• determining the plurality of linearly related phases in accordance with the feedback, including
• determining an impulse response of the communication channel h(m) in accordance with the pre-determined model and the parameters;
• determining indexes m1 and m2 for the largest and the second largest magnitudes of the impulse response of the communication channel h(m);
• determining a phase of Chh(mmax), wherein mmax=m1−m2;
• determining a phase of Css(mmax);
• and
• determining the plurality of linearly related phases in accordance with the phases of Chh(mmax) and the Css(mmax);
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• receiving a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• determining the plurality of linearly related phases in accordance with the feedback;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence, including evaluating for each index m an equation:
• s′(m)=ejθ(m)·s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• πα
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is number of phases.

Computer readable media embodying a method for adapting an effective spreading sequence in a communication system, the method comprising:

• receiving a feedback signal comprising information enabling determination of a plurality of linearly related phases;
• determining the plurality of linearly related phases in accordance with the feedback;
• and
• applying at least one of the plurality of linearly related phases to at least one sample of the effective spreading sequence including evaluating for each index m an equation:
• s′(m)=e−jθ(m)s(m)
• wherein:
• s′(m) is the adapted spreading sequence;
• s(m) is the effective spreading sequence;
• j is an imaginary unit;
• θ
• 
• (
• m
• )
• =
• 2
• 
• πα
• 
• 
• m
• M
• is the m-th phase;
• α is a phase factor;
• and
• M is the number of phases.