One of the main goals of 5G wireless telecommunication technology is improving energy efficiency, especially of remote sensors which should be able for example to transmit on average 1bit/s for 10 years from a single AAA battery. There will be discussed using modulation with nonuniform probability distribution of symbols for improving energy efficiency of transmission at cost of reduced throughput. While the zero-signal (silence) has zero energy cost to emit, it can carry information if used alongside other symbols. If used more frequently than others, for example for majority of time slots or OFDM subcarriers, the number of bits transmitted per energy unit can be significantly increased. For example for hexagonal modulation and zero noise, this amount of bits per energy unit can be doubled by reducing throughput 2.7 times, thanks to using the zero-signal with probability $\approx$ 0.84. There will be discussed models and methods for such nonuniform probability modulations (NPM).