Continuously available net entry synchronization technique

The design and performance of a net entry synchronization technique for use in a high-hop-rate antijam system is presented. The technique transmits a continuous hidden preamble, imbedded in the communication waveform, to allow new units with large initial time error to enter the network by aligning their timing with the network time. Since the hidden preamble is continuously transmitted, any unit can enter the network at any time, and can repeat the acquisition process as many times as necessary to achieve specific performance requirement. A net entry process is essential to establishing a frequency-hopping communication network. The net entry synchronization concept presented can be applied to all frequency-hopping networks, but the design is particularly refined for protection against the communication jamming and multipath fading found in the high-frequency (HF) communication band. The synchronization scheme is analyzed, and it is shown that in a Rayleigh fading channel, with a signal-to-noise ratio of 8 dB, a receiver can achieve 99% probability of network entry within 3.25 s