Abstract: According to an aspect, there is provided a first apparatus configured to perform the following. The first apparatus transmits a first notification message via a tunable small-form pluggable, SFP, module on a first channel over an optical transport network to a second apparatus by applying on-off keying to an optical transmitter of the SFP module. The first notification message includes information on the first channel. The first apparatus receives a first notification response message via the tunable SFP module from the second apparatus as an on-off keyed transmission on the first channel or a second channel. The first notification response message includes the information on the first channel. The first apparatus evaluates the first notification response message for acquiring the information on the first channel.

Abstract: A method of designing an antenna (6) comprises at least two iterations (8, 10); wherein a first iteration (8) comprises applying a first order fractal replication (b) to a base shape (7); and wherein a subsequent iteration (10) comprises applying a non-linear replication to the result of the first or each previous iteration (8, 9); such that a predetermined antenna radiation pattern is produced (11). An antenna comprises at least two elements; wherein the first element comprises a base shape (7) to which a first order fractal replication (b) has-been applied; and wherein a subsequent element comprises a non-linear replication of the first or each subsequent element, such that a predetermined antenna radiation pattern is produced (11).