Operating a communication system comprises providing N transmitting antennas (TA) for transmitting symbol streams (SST) and K ground receivers (GR) which may be provided with symbol streams (SST) transmitted by transmitting antennas (TA). Transmitting antennas (TA) are located with a distance from Earth (E). Ground receivers (GR) are spatially separated from each other, wherein the constraint K>N applies. The method includes: simultaneously transmitting N symbol streams (SST) by N transmitting antennas (TA), receiving a linear combination of N simultaneously transmitted symbol streams (SST) by each ground receiver (GR), respectively, determining the respective linear combination for N transmitting antennas (TA) and each of the K ground receivers (GR), respectively, deciding on the basis of the determined linear combinations which of the K ground receivers (GR) is assigned to a respective common receiver group in order to be simultaneously and with the same frequency provided with symbol streams (SST).