Abstract: A method of opportunistic access to a frequency band dedicated to a synchronous primary network by a secondary user. The frequency band is divided into K independent channels to which an indicator Bk and an average availability Sk are assigned. At each time frame t, the method includes observing, by the secondary user, the channel i having the greatest indicator Bi(t); and if the channel i is busy, updating the average availability Si of channel i and updating indicator Bi (t) of the channel as a function of Si, and if the channel i is free: updating the average availability Si of channel i, transmitting data set up during the frame t on channel i, computing a quality index Ri (t) of channel i, and updating indicators Bk (t) of the K channels as a function of the average availabilities Sk and Ri (t).

Abstract: A method is provided for transmitting a sequence of data symbols including at least two data symbols of distinct values, delivering an electromagnetic wave carrying an orbital angular momentum. The method includes, for at least one data symbol to be transmitted: a bijective selection of an order of orbital angular momentum associating, with each distinct value of a data symbol, a distinct order of orbital angular momentum, and delivering a selected order of orbital angular momentum that is representative, by bijection, of the value of the at least one data symbol to be transmitted; and transmitting the electromagnetic wave carrying an orbital angular momentum, the order of orbital angular momentum of which corresponds to the selected order of orbital angular momentum.

Abstract: A method of opportunistic access to a frequency band dedicated to a synchronous primary network by a secondary user. The frequency band is divided into K independent channels to which an indicator Bk and an average availability Sk are assigned. At each time frame t, the method includes observing, by the secondary user, the channel i having the greatest indicator Bi(t); and if the channel i is busy, updating the average availability Si of channel i and updating indicator Bi (t) of the channel as a function of Si, and if the channel i is free: updating the average availability Si of channel i, transmitting data set up during the frame t on channel i, computing a quality index Ri (t) of channel i, and updating indicators Bk (t) of the K channels as a function of the average availabilities Sk and Ri (t).

Abstract: A method is provided for transmitting a sequence of data symbols including at least two data symbols of distinct values, delivering an electromagnetic wave carrying an orbital angular momentum. The method includes, for at least one data symbol to be transmitted: a bijective selection of an order of orbital angular momentum associating, with each distinct value of a data symbol, a distinct order of orbital angular momentum, and delivering a selected order of orbital angular momentum that is representative, by bijection, of the value of the at least one data symbol to be transmitted; and transmitting the electromagnetic wave carrying an orbital angular momentum, the order of orbital angular momentum of which corresponds to the selected order of orbital angular momentum.