A novel hybrid narrowband/wideband networking waveform physical layer for multiuser multiband transmission and reception in software defined radio

Abstract

Increasing demands of adaptability and reconfigurability impose many challenges on the design of Software Defined Radio (SDR) waveforms for highly heterogeneous wireless networks. Usually, narrowband waveforms provide robustness and work for longer distances but lack in providing higher throughput, whereas wideband waveforms provide much higher throughput but they are not much robust and operate for smaller distances. A heterogeneous SDR network having diverse Quality of Service (QoS) and range requirements, and channel conditions cannot fully rely on one of the narrowband or wideband waveform. In this paper, a novel hybrid narrowband/wideband networking waveform physical layer is proposed. The proposed waveform is based on simultaneous transmission and reception of signals having multiple bandwidths through minimal changes in the existing analog wideband front end. A digital front end architecture is proposed where sample rate conversion and channelization of multiple signals at the digital front end formulate a composite signal which is then transmitted by using the wideband RF front end settings of a wideband waveform. At the receiver, the composite signal is received by using the wideband RF front end configured to wideband mode. Individual downconversion and filtering of each of the respective signal is done digitally. In this way, multiple signals having bandwidths as per their QoS and range requirements can be transmitted/received through the same wideband front end. As a proof of concept, the proposed idea is validated on actual SDR platform by taking actual dumps from FPGA and DSP. The presented results show the viability of the proposed hybrid SDR waveform.