Capacity of BICM Using (Bi-)Orthogonal Signal Constellations in   Impulse-Radio Ultra-Wideband Systems
  Bit-interleaved coded modulation (BICM) using (bi-)orthogonal signals is especially well suited for the application in impulse-radio ultra-wideband transmission systems, which typically operate in the power-limited regime and require a very low-complexity transmitter and receiver design. In this paper we analyze the capacity of BICM using (bi-)orthogonal signals with coherent and noncoherent detection and put particular focus on the power-limited or wideband regime. We give analytical expressions for the ratio energy per bit vs. noise power spectral density in the limit of infinite bandwidth and the respective wideband slope, and thus, are able to quantify the loss incurred by the restriction to BICM in contrast to coded modulation. The gained theoretical insights allow to derive design rules for impulse-radio ultra-wideband transmission systems. 
Andreas Schenk and Robert F.H. Fischer
cs.IT math.IT