Data are transmitted and/or received in a communication system by a communication participant, which has a communication device, a microprocessor, and an energy supply. The latter has an electrical variable that changes from an initial value when it supplies the microprocessor and/or the communication device with energy. The microprocessor encodes the data before transmission and/or decodes the data after reception, each using a computing cycle. When the electrical variable changes during the computing cycle, it is interrupted, preferably at any desired point. The encoding and/or decoding are carried out separately during the computing cycle in individual encoding phases in which the value of the electrical variable changes. Regeneration phases for regenerating the electrical variable are provided between and/or within the encoding phases. The duration of a regeneration phase is such that the value of the electrical variable approaches or reaches the initial value during the regeneration phase.