  In wireless network communication environments, Spectral Efficiency (SE) and
Energy Efficiency (EE) are among the major indicators used for evaluating
network performance. However, given the high demand for data rate services and
the exponential growth of energy consumption, SE and EE continue to elicit
increasing attention in academia and industries. Consequently, a study of the
trade-off between these metrics is imperative. In contrast with existing works,
this study proposes an efficient SE and EE trade-off algorithm for saving
energy in downlink Long Term Evolution (LTE) networks to concurrently optimize
SE and EE while considering battery life at the Base Station (BS). The scheme
is formulated as a Multi-objective Optimization Problem (MOP) and its Pareto
optimal solution is examined. In contrast with other algorithms that prolong
battery life by considering the idle state of a BS, thereby increasing average
delay and energy consumption, the proposed algorithm prolongs battery life by
adjusting the initial and final states of a BS to minimize the average delay
and the energy consumption. Similarly, the use of an omni-directional antenna
to spread radio signals to the user equipment in all directions causes high
interference and low spatial reuse. We propose using a directional antenna
instead of an omni-directional antenna by transmitting signals in one direction
which results in no or low interference and high spatial reuse. The proposed
scheme has been extensively evaluated through simulation, where simulation
results prove that the proposed scheme is efficiently able to decrease the
average response delay, improve SE, and minimize energy consumption.
