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Massive MIMO (MM) is one of the leading technologies that can cater for very high capacity demand. However, energy consumption of MM systems needs to be load adaptive in order to cope with the significant temporal load variations (TLV) over a day. In this paper, we propose a game-theoretic model for studying load adaptive multicell massive MIMO system where each base station (BS) adapts the number of antennas to the TLV in order to maximize the downlink energy efficiency (EE). The utility function considered here is defined as the number of bits transferred per Joule of energy. In order to incorporate the TLV, the load at each BS is modeled as an $M/G/m/m$ state dependent queue under the assumption that the network is dimensioned to serve a maximum number of users at the peak load. The EE maximization problem is formulated in a game theoretic framework where the number of antennas to be used by a BS is determined through the best response iteration. This load adaptive system achieves around 24% higher EE and saves around 40% energy compared to a baseline system where the BSs always run with the fixed number of antennas that is most energy efficient at the peak load and that can be switched off when there is no traffic. [ABSTRACT FROM AUTHOR]

In this paper, we study the energy-delay trade-off in the downlink of a proportional-fair cellular system with inter-cell interference and fading, while incorporating the efficiency characteristics of realistic amplifiers(PA). We study the potential for energy saving by lowering the transmission power level at different user locations in a cell at the cost of additional flow level delay. We identify the transmission power levels at different locations so that the energy consumption at the base station is minimized and the flow level delay is controlled. We formulate the energy minimization problem in a game theoretic framework and prove the convergence of the best response iteration algorithm. The energy saving potential is found to depend on the network load and the efficiency characteristics of the PAs. There is a significant potential for energy saving when the network operates under low to medium loads and efficient PAs are utilized. For example, with envelope tracking PA, around 90% of energy can be saved by introducing small additional flow level delay when the network load is less than 75%. Motivated by the fact that the network load keeps varying throughout the day, we take a daily traffic model and demonstrate the potential for energy saving by this scheme. [ABSTRACT FROM PUBLISHER]

Solving a time-dependent two-dimensional local thermodynamic equilibrium (LTE) model simulation of Ar and Ar-H2 atmospheric pressure, a high-power RF-induction thermal plasma was performed. The effects of shimmer current level (SCL) in pulse-modulated mode and hydrogen concentrations on different flow fields were predicted. The radiation intensities of Ar I (751 nm) for different SCL were calculated from the temperature fields. For the same operating conditions as simulation, plasma was successfully generated in pulse-modulated mode and spectroscopic measurements were carried out to investigate the effects of SCL upon temporal plasma properties. Response times (rising, falling, on-delay, and off-delay time) of temporal radiation intensity were crosschecked for both experimental and simulated ones. The rising time increased gradually with the decrease of SCL, though the falling time remained almost unchanged with SCL. For example, for Ar plasma at 86%, 79%, 72%, 65%, 50%, and 40% SCL the rising times were 2.7, 3.0, 3.4, 3.4, 3.6, and 3.8 ms, respectively. And for Ar-H2 plasma (2.4% H2), at 87%, 77%, 72%, 63%, 55%, and 45% SCL, rising times were 2.5, 3.0, 3.0, 3.4, 3.7, 3.9, and 4.0 ms, respectively. Hydrogen inclusion slowed down the plasma response during the off-to-on pulsing transition at lower SCL and constricted the plasma axially. Finally, part of the simulated results was compared with experimental determinations and acceptable agreements were found. The discrepancies, in few cases, explicated mainly that the LTE assumption did not prevail in pulse-modulated plasma, especially around the on-pulse transition [ABSTRACT FROM PUBLISHER]