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This paper describes a digital signal processing (DSP) method for achieving “ideal” amplification, maximizing both the average output signal power and power-added-efficiency for any signal waveform and any power amplifier (PA) transfer characteristic. Detailed algorithms are described for optimally accomplishing peak reduction (PR), predistortion (PD) linearization, and integration of these DSP techniques with envelope tracking PAs. Hardware characterization results validate the theories of PD and PR operation.

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BWA must make sound business sense to be a successful 'last-mile' solution technology, for it faces stiff cost competition from phone-line and cable broadband-access alternatives. The challenge to modem designers is to develop technology which improves the BWA return-on-investment @OX), to wit minimize the installed equipment (total system, not just modem) cost while maximizing the data-bearing capacity of millimeter-wave links. Broadband wireless access (BWA) links exhibit pathologies and cost models distinct from those of wired links, and these distinctions should be reflected in a well-designed BWA modem. This tutorial paper discusses BWA ROI within the context of a system-level cost concept, relates this model to primary LMDS link pathologies, and suggests several modem-level features which will be required to address BWA ROI challenges. A few specific modem design approaches will be noted to demonstrate that these BWA design challenges are readily addressable.