A wireless broadband communication system that operates with high efficiency and reduced latency in long range point-to-point and point-to-multipoint applications. The system includes multiple transceivers and multiple antennas for transmitting and receiving wireless signals using TDD techniques over multiple channels, which include a control channel for setting both the size of the transmit bursts and the modulation threshold level. By determining the size of the transmit bursts for a subsequent data transmission based upon the number of filler packets detected in a specified number of previously received bursts, and adjusting the modulation threshold level for the subsequent transmission based upon the transmit burst size, the system provides increased data throughput, while maintaining the packet error rate at an acceptable level. As the throughput requirements of the system are relaxed, the modulation threshold levels can be adjusted to provide reduced packet error rates.