ABSTRACT
The evolution of software defined radio (SDR) systems has placed us at a crossroads. SDR systems increasingly find themselves vital to the ecosystem of defense communications, civilian cellular and noncellular wireless systems. Continued CMOS digital device shrinkages and ever increasing clock and A=D rates enable more and more opportunities for direct RF sampling of the antenna port waveforms. The enabled digital samples can be processed in flexible software rather than fixed hardware. This leads to a desire for multiprotocol support to enable multiple services, a desire to incorporate the most sophisticated signal processing algorithms to achieve maximum network capacity, and license band sensing and avoidance regimes in support of cognitive radio. In this paper, we present a survey of the important five trends in SDR system infrastructure: waveform signal processing, capacity extending communication radio link processing, RF, IF or A=D band-pass modulation and demodulation, software architectures, and reconfigurable hardware architectures. Finally, we discuss SDR systems that can support the broadband, gigabit cellular protocol known as 3GPP long term evolution-advanced (LTE-advanced).
