Reference signal management

A method comprising:

• selecting a reference signal sequence for a first signal based on a first number of resource blocks located in a frequency interval;
• determining a second number of resource blocks located outside the frequency interval via spectrally extending the first signal, determining whether the second number is an odd number, and based on determining that the second number is an odd number, applying a frequency shift to the first signal and extending the selected reference signal sequence by performing one of the following:
• applying a cyclic shift to the selected reference signal sequence and then applying a cyclic extension to the selected reference signal sequence at both ends of the selected reference signal sequence, or
• applying a cyclic extension to the selected reference signal sequence, wherein the cyclic extension is by a third number of sequence elements at a first end of the sequence and by a fourth number of sequence elements at a second end of the sequence, wherein the third number of sequence elements is greater than the fourth number of sequence elements, and
• mapping the extended reference signal sequence to the resource blocks located in the frequency interval and the resource blocks located outside the frequency interval, performing spectral shaping of a second signal comprising the resource blocks located both inside and outside the frequency interval, and transmitting the second signal in uplink direction.

An apparatus comprising at least one processing core and at least one memory storing instructions that, when executed by the at least one processing core, cause the apparatus at least to:

• select a reference signal sequence based on a first number of resource blocks located inside a frequency interval in an uplink transmission received by the apparatus;
• determine a second number of resource blocks located outside the frequency interval via spectrally extending the uplink transmission, determine whether the second number is an odd number, and based on determining that the second number is an odd number, apply a frequency shift to the uplink transmission received by the apparatus and extend the selected reference signal sequence by performing one of the following:
• applying a cyclic shift to the selected reference signal sequence and then applying a cyclic extension to the selected reference signal sequence at both ends of the selected reference signal sequence, or
• applying a cyclic extension to the selected reference signal sequence, wherein the cyclic extension is by a third number of sequence elements at a first end of the sequence and by a fourth number of sequence elements at a second end of the sequence, wherein the third number of sequence elements is greater than the fourth number of sequence elements, and
• employ the extended reference signal sequence in reception of the uplink transmission in the apparatus.