Fixed Link Margins Outperform Power Control in Energy-Limited Wireless Sensor Networks

We investigate whether adapting the transmit power optimally to the time-varying channel compares favorably, in terms of total energy consumption, to using a fixed link margin in wireless networks over short transmission distances. Over short distances, the circuit energy consumption dominates the transmission energy. For that reason, feeding back channel state information a requirement for power control - may not be a power efficient strategy. We investigate both slow and fast power control and conclude, somewhat surprisingly, that using a fixed margin is typically more power-efficient than using power control.