A secure frequency hopping synthesizer for reconfigurable wireless radios

Frequency-hopping is a method by which the carrier of a transmitting radio signal will rapidly switch among many frequency channels, using a pseudorandom sequence known to both transmitter and receiver. This rapid switching of the carrier frequencies during transmission will minimize the unauthorized interception or jamming of telecommunications. Any radio with a digitally controllable frequency synthesizer can work as a hopping radio. The Frequency synthesizer has a limitation that the frequency band is limited, so for supporting wider band more synthesizers are required which will consume more area in the board and power consumption will be larger. Here the hopping synthesizer is implemented using partial Re-configuration so that the user can load different NCOs in FPGAs depending on the requirements and as a result a wide range of frequency band is supported. The security of a hopping radio mainly depends on the Pseudo-random sequence generator which will generate the control word for the frequency synthesizer (DDS). The BlumBlum-Shub generator (BBS) is cryptographically secure random sequence generator. In BBS algorithm the randomness is achieved by modulo squaring a number and extracting a set of lower bits from the generated numbers]. The generated random numbers control a Direct Data Synthesizer (DDS) to produce the required hopping frequencies. Here the design consists of a static part and Dynamic part. The Pseudo random number generator will form the static part and a frequency table and the DDS will form the dynamic part. The entire system is implemented in a Virtex-6 FPGA using VHDL and verified using Hardware-in the -Loop Simulation in the Matlab Environment.