Cooperative Multi-Sensor Detection under Variable-Length Coding

We investigate the testing-against-independence problem over a cooperative MAC with two sensors and a single detector under an average rate constraint on the sensors-detector links. For this setup, we design a variable-length coding scheme that maximizes the achievable type-II error exponent when the type-I error probability is limited to ϵ. Similarly to the single-link result, we show here that the optimal error exponent depends on ϵ and that variable-length coding allows to increase the rates over the optimal fixed-length coding scheme by the factor (1 − ϵ)
⁻¹
.