Method for radio-based transmission of communication data by means of a first radio communication system, comprising - transmitting the communication data from at least one first transmitting unit to at least one first receiving unit by means of the first radio communication system, - wherein the first radio communication system is allocated one or more first transmission frequencies in order to allow the first transmitting unit to transmit, and to allow the first receiving unit to receive, a first radio signal , containing the communication data, on at least one of these first transmission frequencies using the first radio communication system, characterized by - transmitting at least one pilot symbol from a second transmitting unit to at least one second receiving unit by means of a second radio communication system, which is different from the first radio communication system, - wherein the second radio communication system is allocated one or more second transmission frequencies, which are different from the first transmission frequencies of the first communication system, in order to allow the second transmitting unit to transmit, and to allow the second receiving unit to receive, a second radio signal , containing the at least one pilot symbol, on at least one of these second transmission frequencies using the second radio communication system, - wherein the pilot symbol is transmitted by the second transmitting unit in a second radio signal on at least one of the second transmission frequencies, which is situated within the coherence bandwidth of the first transmission frequency that was used to transmit the communication data by means of the first radio communication system, and - performing a channel estimation of the transmission channel of the first radio communication system that was used to transmit the communication data on the basis of the received second radio signal containing the at least one pilot symbol by means of an evaluation unit. - transmitting the communication data from at least one first transmitting unit to at least one first receiving unit by means of the first radio communication system, - wherein the first radio communication system is allocated one or more first transmission frequencies in order to allow the first transmitting unit to transmit, and to allow the first receiving unit to receive, a first radio signal , containing the communication data, on at least one of these first transmission frequencies using the first radio communication system, - transmitting at least one pilot symbol from a second transmitting unit to at least one second receiving unit by means of a second radio communication system, which is different from the first radio communication system, - wherein the second radio communication system is allocated one or more second transmission frequencies, which are different from the first transmission frequencies of the first communication system, in order to allow the second transmitting unit to transmit, and to allow the second receiving unit to receive, a second radio signal , containing the at least one pilot symbol, on at least one of these second transmission frequencies using the second radio communication system, - wherein the pilot symbol is transmitted by the second transmitting unit in a second radio signal on at least one of the second transmission frequencies, which is situated within the coherence bandwidth of the first transmission frequency that was used to transmit the communication data by means of the first radio communication system, and - performing a channel estimation of the transmission channel of the first radio communication system that was used to transmit the communication data on the basis of the received second radio signal containing the at least one pilot symbol by means of an evaluation unit. <EOS>