Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers

Abstract

Abstract. A new receiving scheme for self-mixing receivers is presented that overcomes the disadvantages of the selfheterodyne concept. Generally speaking, the self-mixing receiver offers immunity to phase noise and frequency offsets, especially at very high frequencies, since it does not require radio frequency local oscillators. Our proposed technique eliminates the drawbacks of the self-heterodyne transmission scheme, which are the poor power efficiency and the strong dependence on the continously transmitted carrier.A nonlinear system of equations is constructed that describes a phase retrieval problem for the reconstruction of the original transmit signal before self-mixing. Two different solution strategies, with restrictions in time and frequency domain, are presented. As a consequence, the self-mixing equation system is shown to be solvable with some a-priori information about the transmit signal. With this novel approach, the transmitted information is distributed over the full available bandwidth, and there is no special dependence on a certain subcarrier for the down-conversion.The general performance, regarding bit error ratio over signal to noise ratio, is improved by at least 2 dB as compared to the self-heterodyne transmission scheme. In the case of frequency selective channels, e.g. multi-path propagation, this improvement is shown to be much larger, because the presented approach is able to reconstruct the received subcarriers without the necessity of receiving all subcarriers.

A Non-Reciprocal Receive Array with Large Beamwidth and Gain

“…Special signal schemes have to be employed to enable the reconstruction of the receive signal after selfmixing, e.g. the self-heterodyne transmission technique [10]- [13]. Recently, it was found that self-mixing arrays offer a large receive gain over a wide angular range which is not possible for reciprocal antenna systems with super-heterodyne receivers [14], [15].…”

A Millimeter-Wave Self-Mixing Array With Large Gain and Wide Angular Receiving Range

“…in optics [30]- [36] or acoustic underwater communications [37]- [39]. Recent research in the field of self-heterodyne transmission techniques concentrates on studying the effects of self-mixing arrays [19] and on improving the transmission technique on a signal processing level [40]- [44] or even on extending the self-mixing technique to a more general approach without an explicitly transmitted carrier signal [45]. Also, the analogue receiver circuit can be improved as compared to a simple square-law detector by employing the self-coherent technique [46].…”