  We consider a binary hypothesis testing problem using Wireless Sensor
Networks (WSNs). The decision is made by a fusion center and is based on
received data from the sensors. We focus on a spectrum and energy efficient
transmission scheme used to reduce the spectrum usage and energy consumption
during the detection task. We propose a Spectrum and Energy Efficient Multiple
Access (SEEMA) transmission protocol that performs a censoring-type
transmission based on the density of observations using multiple access
channels (MAC). Specifically, in SEEMA, only sensors with highly informative
observations transmit their data in each data collection. The sensors transmit
a common shaping waveform and the fusion center receives a superposition of the
analog transmitted signals. SEEMA has important advantages for detection tasks
in WSNs. First, it is highly energy and bandwidth efficient due to transmission
savings and narrowband transmission over MAC. Second, it can be implemented by
simple dumb sensors (oblivious to observation statistics, and local data
processing is not required) which simplifies the implementation as compared to
existing MAC transmission schemes for detection in WSNs. We establish a finite
sample analysis and an asymptotic analysis of the error probability with
respect to the network size and provide system design conditions to obtain the
exponential decay of the error. Specific performance analysis is developed for
common non-i.i.d. observation scenarios, including local i.i.d. observations,
and Markovian correlated observations. Numerical examples demonstrate SEEMA
performance.
