Performance of a Software Defined Radio based Non-Coherent OFDM Wireless Link

Abstract

With improved technological successions, wireless communication applications have been incessantly evolving. Owing to the challenges posed by the multipath wireless channel, radio design prototypes have become elemental in all wireless systems before deployment. Further, different signal processing requirements of the applications, demand a highly versatile and reconfigurable radio such as Software Defined Radio (SDR) as a crucial device in the design phase. In this paper, two such SDR modules are used to develop an Orthogonal Frequency Division Multiplexing (OFDM) wireless link, the technology triumphant ever since 4G. In particular, a non-coherent end-to-end OFDM wireless link is developed in the Ultra High Frequency (UHF) band at a carrier frequency of 470 MHz. The transmitter includes Barker sequences as frame headers and pilot symbols for channel estimation. At the receiver, pulse alignment using Max energy method, frame synchronization using sliding correlator approach and carrier offset correction using Moose algorithm are incorporated. In addition, wireless channel is estimated using Least Square (LS) based pilot aided channel estimation approach with denoising threshold and link performance is analyzed using average Bit Error Rate (BER), in different pilot symbol scenarios. In a typical laboratory environment, the results of BER versus receiver gain show that with 4 pilot symbols out of 128 carriers, at a gain of 20 dB, BER is 0.160922, which is reduced to 0.136884 with 16 pilot symbols. The developed link helps OFDM researchers to mitigate different challenges posed by the wireless environment and thereby strengthen OFDM technology.

Keywords

• software defined radio (sdr)
• universal software radio peripheral (usrp)
• labview
• ls channel estimation
• denoising threshold