Transmission of pilot sequences

A coordinator configured to coordinate simultaneous transmissions of different pilot sequences of pilot signals to be transmitted by a plurality of transmitters, the plurality of transmitters comprising at least one first transmitter and one second transmitter,

• wherein the coordinator is configured to assign:
• to the first transmitter, a plurality of codes comprising at least one first code and at least one second code, the at least one first code and at least one second code being codes of a set of codes;
• and
• to the second transmitter, a plurality of additional codes comprising at least one first additional code and at least one second additional code, the at least one first additional code and the at least one second additional code being codes of the set of codes, the at least one first additional code being orthogonal to the at least one first code, and the at least one second additional code being orthogonal to the at least one second code,
• wherein the coordinator is configured to select, for each transmitter of the plurality of transmitters, at least one symbol rate among a plurality of symbol rates comprising at least one first, lower symbol rate and one second, higher symbol rate,
• wherein the coordinator is configured to signal, to the first transmitter, the at least first code and the at least one second code assigned the first transmitter and to signal, to the second transmitter, the at least one first additional code and the at least one second additional code assigned the second transmitter,
• wherein the coordinator is configured to signal, to each transmitter, the selected symbol rate, so that:
• in case of the first symbol rate being selected for the first transmitter, the first transmitter transmits a first pilot sequence comprising a first set of equally spaced symbols,
• in case of the second symbol rate being selected for the first transmitter, the first transmitter transmits a second pilot sequence comprising the at least one first set of equally spaced symbols and at least one second set of equally spaced symbols interleaved with the at least one first set of equally spaced symbols,
• in case of the first symbol rate being selected for the second transmitter, the second transmitter transmits a first additional pilot sequence comprising at least one first additional set of equally spaced symbols, and
• in case of the second symbol rate being selected for the second transmitter, the second transmitter transmits a second additional pilot sequence comprising the at least one first additional set of equally spaced symbols and at least one second additional set of equally spaced symbols interleaved with the at least one first set of equally spaced symbols,
• in such a way that the first transmitter transmits the first pilot sequence at a first symbol rate and the second pilot sequence at a second symbol rate which is multiple, according to a predetermined integer coefficient, of the first symbol rate, while the time length of the first pilot sequence is the same of the time length of the second pilot sequence,
• wherein the sum of the number of symbols of the at least one first set of equally spaced symbols and the number of at least one second set of equally spaced symbols is a multiple of the at least one first set of equally spaced symbols according to the predetermined integer coefficient, the predetermined integer coefficient being greater than 1, the first and second transmitters transmitting the selected pilot sequence according to a pulse amplitude modulation, PAM.

A receiver for receiving a pilot signal transmitted by a transmitter, the receiver being configured to obtain phase information of the pilot signal from a pilot sequence in the pilot signal, the pilot sequence comprising a plurality of sets of equally spaced symbols interleaved with each other,

• wherein the receiver is configured to perform an evaluation operation evaluating a correlation between the pilot sequence and pre-stored versions of the plurality of sets of equally spaced symbols, thereby determining the set of codes with highest correlation with the pilot sequence, so as to obtain phase information from the determination of the set of codes with highest correlation with the pilot sequence,
• wherein the pilot sequence is transmitted, through a pulse amplitude modulation, PAM, at a symbol rate which is selected among a plurality of symbol rates, wherein the pilot sequence at a first symbol rate is a first pilot sequence comprising at least one first set of equally spaced symbols, and the pilot sequence at a second symbol rate higher than the first symbol rate is a second pilot sequence comprising the at least one first set of equally spaced symbols interleaved with the at least one second set of equally spaced symbols,
• wherein the receiver is configured to selectably:
• in case of reception only of the first pilot sequence at the first symbol rate, sample the pilot sequence at the first symbol rate, thereby evaluating the correlation between the first pilot sequence and pre-stored version(s) of the at least one first set of equally spaced symbols;
• and
• in case of reception of the second pilot sequence at the second symbol rate, to:
• either sample the second pilot sequence at the second symbol rate, evaluating a correlation between the second pilot sequence and pre-stored version(s) of the at least one first set of equally spaced symbols interleaved with the at least one second of set of equally spaced symbols, or
• sample the second pilot sequence at the first symbol rate, evaluating a correlation between the second pilot sequence and pre-stored version(s) of the at least one first set of equally spaced symbols.

Method for transmitting a pilot signal comprising a pilot sequence selected among a plurality of pilot sequences comprising at least a first pilot sequence and a second pilot sequence,

• wherein the first pilot sequence comprises a plurality of symbols of the first pilot sequence;
• wherein the second pilot sequence comprises the symbols of the first pilot sequence and further symbols of the second pilot sequence inserted in between the symbols of the first pilot sequence,
• the method comprising defining:
• the symbols of the first pilot sequence to comprise at least one first set of equally spaced symbols, each first set of equally spaced symbols representing a respective first code;
• and
• the symbols of the second pilot sequence to comprise at least one second set of equally spaced symbols, each second set of equally spaced symbols representing a respective second code which is different from each first code,
• the method comprising selecting each first code and each second code from a set of codes in which each code of the set of codes is orthogonal to at least one other non-selected code of the set of codes;
• the method comprising transmitting the selected pilot sequence,
• wherein the transmitting comprises transmitting the first pilot sequence at a first symbol rate and the second pilot sequence at a second symbol rate which is multiple, according to a predetermined integer coefficient, of the first symbol rate, while the time length of the first pilot sequence is the same of the time length of the second pilot sequence,
• wherein the sum of the number of symbols of the at least one first set of equally spaced symbols and the number of at least one second set of equally spaced symbols is a multiple of the at least one first set of equally spaced symbols according to the predetermined integer coefficient, the predetermined integer coefficient being greater than 1,
• wherein the selected pilot sequence is transmitted according to a pulse amplitude modulation, PAM.