Method for signal generation in broadband wireless communications, comprises: A. modulating, segmenting and serial-parallel converting the signal data to be transmitted, then computing DFT of the serial-parallel converted data so as to transfer them to frequency domain; B. performing block unit modulating processing and block repeat modulating processing on the frequency domain data, then mapping the block units to assigned time-frequency positions; C. computing IFFT of the mapped block units, then adding them to the cycle prefix, thus the random sequences in time domain are generated. Apparatus for signal generation, Method and system for message transmission in broadband wireless communications are also disclosed. The problem of resource allocation and scheduling, and problem of interference coordination and control are solved, the throughput and performance of communication system are greatly improved.