Engineers migrating to 4G require a solution that makes implementing DPD fast and practical for 4G communications systems, i.e., one that can be used by engineers at all levels of expertise and requires minimal equipment. In modern communication systems, spectrally efficient wideband RF signals have a PAPR as high as 13 dB. CFR preconditions the signal to reduce signal peaks without significant signal distortion. By reducing PAPR, CFR allows the PA to operate more efficiently at higher power levels, without impacting compliance with spectral mask and EVM specifications. CFR acts on the signal itself, whereas DPD corrects for the PA nonlinearity, allowing the signal to be run even higher.
As engineers migrate to the advanced wireless communication systems such as LTE-advanced or 802.11ac, choosing and designing the right PA to meet design goals at the lowest possible cost becomes more difficult, both for base stations and mobile devices. Because DPD enables the PA to be operated with high efficiency, near saturation, and without significant signal distortion, it allows engineers to address many base stations/mobile device PA design challenges. This article considered the design of DPD systems to linearize PAs with memory effects. By adding a digital predistorter in the baseband, the PA is allowed to operate into its nonlinear region, thereby significantly increasing its efficiency. The efficiency gain translates into electricity and cooling cost savings for service providers and longer battery life for mobile terminal users. The challenge here is to address the memory effects exhibited by the higher PAs or the PAs for wideband signals. In addition, analog components in the transmitter have imperfections that need to be compensated as well.
However, the MET response is also activated after a level of deterioration has occurred. The quest continued to find alarm signs or signals that indicate deterioration is likely to occur. Once again, the presumption is that an earlier response, before deterioration has occurred, should result in a better outcome. 153554b96e