* \brief Request the maximum number of bytes that can be served by RLC instance to MAC and fix the amount of bytes requested by MAC for next RLC transmission.
* \return A PDU of the previously requested number of bytes, and the updated maximum number of bytes that can be served by RLC instance to MAC for next RLC transmission.
* \brief Segmentation procedure with 10 bits sequence number, segment the first SDU in buffer and create a PDU of the size (nb_bytes_to_transmit) requested by MAC if possible and put it in the list "pdus_to_mac_layer".