Signaling using phase rotation techniques in a digital communications system

In a digital telecommunications system, a method for conveying modulation information from a transmitter to a receiver, said method comprising the steps of:

• selecting one of a plurality of modulation schemes;
• modulating a sequence of training symbols in accordance with the selected one of the plurality of modulation schemes;
• identifying a phase rotation factor which corresponds to the selected one of the plurality of modulation schemes, wherein at least one unique phase rotation factor is associated with each of the plurality of modulation schemes;
• rotating the phase of each training symbol as a function of the identified phase rotation factor which corresponds to the selected one of the plurality of modulation schemes;
• transmitting the sequence of phase-rotated training symbols to the receiver;
• at the receiver, generating a sequence of de-rotated training symbols for each phase rotation factor by de-rotating the received sequence of phase-rotated training symbols as a function of each phase rotation factor;
• comparing each sequence of de-rotated training symbols to an expected sequence of training symbols;
• identifying the sequence of de-rotated training symbols that approximates the expected sequence of training symbols most accurately;
• and
• identifying the selected one of the plurality of modulation schemes based on the phase rotation factor that produced the sequence of de-rotated training symbols that most closely approximated the expected sequence of training symbols.

In a digital telecommunications system, a method for identifying signaling information transmitted from a transmitter to a receiver along with data, said method comprising the steps of:

• receiving a signal containing a sequence of symbols transmitted from the transmitter, wherein the symbols include training symbols and data symbols, and wherein the phase associated with each symbol in the sequence of symbols has been rotated at the transmitter in accordance with a common phase rotation factor that corresponds to the signaling information;
• generating samples from the received signal, wherein the samples correspond to the sequence of transmitted symbols;
• recovering the sequence of transmitted symbols by de-rotating the samples in accordance with the common phase rotation factor;
• and
• identifying the signaling information as a function of the common phase rotation n factor used to recover the sequence of transmitter symbols.

In a digital telecommunications system, an apparatus for transmitting signaling information from a transmitter to a receiver comprising:

• means for identifying one of a plurality of information signals to be conveyed from the transmitter to the receiver in addition to data;
• means for rotating each of one or more symbols by a common phase rotation factor, wherein the phase rotation factor uniquely identifies the one information signal to be conveyed from the transmitter to the receiver;
• and
• means for transmitting each of the one or more phase-rotated symbols to the receiver.

In a digital telecommunications system, an apparatus for conveying modulation information from a transmitter to a receiver, said apparatus comprising:

• means for selecting one of a plurality of modulation schemes;
• means for modulating a sequence of training symbols in accordance with the selected one of the plurality of modulation schemes;
• means for identifying a phase rotation factor which corresponds to the selected one of the plurality of modulation schemes, wherein at least one unique phase rotation factor is associated with each of the plurality of modulation schemes;
• means for rotating the phase of each training symbol as a function of the identified phase rotation factor which corresponds to the selected one of the plurality of modulation schemes;
• means for transmitting the sequence of phase-rotated training symbols to the receiver;
• at the receiver, means for generating a sequence of de-rotated training symbols for each phase rotation factor by de-rotating the received sequence of phase-rotated training symbols as a function of each phase rotation factor;
• means for comparing each sequence of de-rotated training symbols to an expected sequence of training symbols;
• means for identifying the sequence of de-rotated training symbols that approximates the expected sequence of training symbols most accurately;
• and
• means for identifying the selected one of the plurality of modulation schemes based on the phase rotation factor that produced the sequence of de-rotated training symbols that most closely approximated the expected sequence of training symbols.

In a digital telecommunications system, a apparatus for identifying signaling information transmitted from a transmitter to a receiver along with data, said apparatus comprising:

• means for receiving a signal containing a sequence of symbols transmitted from the transmitter, wherein the symbols include training symbols and data symbols, and wherein the phase associated with each symbol in the sequence of symbols has been rotated at the transmitter in accordance with a common phase rotation factor that corresponds to the signaling information;
• means for generating samples from the received signal, wherein the samples correspond to the sequence of transmitted symbols;
• means for recovering the sequence of transmitted symbols by de-rotating the samples in accordance with the common phase rotation factor;
• and
• means for identifying the signaling information as a function of the common phase rotation factor used to recover the sequence of transmitted symbols.