Abstract
This paper presents a method to determine transmission power based on power amplifier (PA) operations in order to improve the energy efficiency (EE) of a large-scale (LS) Multiple Input Multiple Output (MIMO)-OFDM system, which is a multi-carrier multiple antenna system with a large amount of transmitter (TX) antennas. Regarding the EE improvement, we propose two kinds of PA operation schemes: increasing the effective TX power (ITXP) and reducing the PA power consumption (RPC) assuming that a reduction of peak-to-average power ratio is applied in the appropriate manner. Closed-form expressions of relative EE are derived for both schemes, and the relative EE of the ITXP scheme is shown to depend on the precoding method that is applied to reduce the inter-user interference, while that of the RPC scheme is independent of the precoding method. The relative EE difference between the ITXP and the RPC schemes is also shown to rely on the occupation ratio of the PA power consumption over the total power consumption. Thus, the EE can remarkably improve by selecting the appropriate scheme based on the circumstances. The results of a simulation also validate the derived closed-form expression of the relative EE.
Highlights
The ever increasing demand for high quality wireless services has resulted in an increase in the power consumption of wireless systems
Since DPD is an expensive device, it cannot be used for LS-Multiple Input Multiple Output (MIMO) due to the excessive amount of TX antennas, while there are numerous well-known peak-to-average power ratio (PAPR) reduction techniques and some can be successfully applied in LS-MIMO-orthogonal frequency-division multiplexing (OFDM) to increase EE [13]
The extension in coverage is not always beneficial in modern high data rate wireless communication systems because one base station (BS) needs to support more users under maintaining a high data transfer services in such a situation. We show that both increasing the effective radiation power based on beamforming effect under maintaining the power amplifier (PA) power consumption, and reducing the effective radiation power based on the degree of beamforming effect under reducing PA power consumption can increase EE significantly
Summary
The ever increasing demand for high quality wireless services has resulted in an increase in the power consumption of wireless systems. Since DPD is an expensive device, it cannot be used for LS-MIMO due to the excessive amount of TX antennas, while there are numerous well-known PAPR reduction techniques and some can be successfully applied in LS-MIMO-OFDM to increase EE [13]. Even though all the previous works provide rather elegant schemes to improve the EE of an LS-MIMO, there is little work focusing on operating PA and relating the operation with the transmission power of the LS-MIMO-OFDM This kind of work is very important from a practical point of view because the power control is based on the PA operation. Reducing the PA power consumption (RPC), for the EE improvement in a LS-MIMO-OFDM system with a PAPR reduction technique.
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