  Most of the existing works on energy-efficient wireless communication systems
only consider the transmitter (Tx) or the receiver (Rx) side power consumption
but not both. Moreover, they often assume the static circuit power consumption.
To be more practical, this paper considers the joint Tx and Rx power
consumption in multiple-access radio networks, where the power model takes both
the transmission power and the dynamic circuit power into account. We formulate
the joint Tx and Rx energy efficiency (EE) maximization problem which is a
combinatorial-type one due to the indicator function for scheduling users and
activating radio links. The link EE and the user EE are then introduced which
have the similar structure as the system EE. Their hierarchical relationships
are exploited to tackle the problem using a divide-and-conquer approach, which
is only of linear complexity. We further reveal that the static receiving power
plays a critical role in the user scheduling. Finally, comprehensive numerical
results are provided to validate the theoretical findings and demonstrate the
effectiveness of the proposed algorithm for improving the system EE.
