Performance of nonorthogonal FSK for the Internet of Things

Low‐complexity BER computation for coherent detection of orthogonal signals

“…In the literature, since the exact result is available, only few research studies have tried to derive a simple BER approximation for coherent detection of orthogonal signals. For instance, the studies concerning the error performance of FSK have focused on upper bounds (UBs) only [16], on quaternary constellations only [17], and on non-orthogonal signaling only [5]. On the other hand, the investigation on the performance of chirp modulation (also known as chirp spread spectrum or LoRa) has considered non-coherent detection only [18][19][20], large constellation sizes only (larger than or equal to 64) [13,21], and non-orthogonal waveforms only [22].…”

“…Among low-rate low-power modulations, it is well known that orthogonal signaling schemes are optimal, because they asymptotically approach the Shannon limit [1]. Orthogonal signaling includes not only FSK [4][5][6][7], whose orthogonality is in the frequency domain, but also other modulation schemes that impose the orthogonality condition in other domains, such as pulse-position modulation (PPM) [8,9], which is orthogonal in the time domain, and chirp modulation [4,[10][11][12][13][14], which is orthogonal in the Fresnel domain [15].…”