Orthogonal Decode and Forward Relaying with Improved Spectral Efficiency

Cooperative relay communications can significantly improve the reliability of data transmission over wireless fading channels by implementing spatial diversity in a distributed fashion. Orthogonal decode and forward (ODF) relaying achieves maximum diversity provided by the source-destination and relaydestination channels, but suffers from low spectral efficiency. We propose a novel ODF protocol having higher spectral efficiency without sacrificing the diversity gain. We analyze the symbol error probability of the proposed protocol and also present simulation results.     

Preparation and characterization studies of metaborates, Cu1?xMxB2O4 (M = Ni, Co and Mn; x = 0, 0·1 and 0·5)

Copper metaborates of Cu_1−x M _x B₂O₄ (M = Ni, Co and Mn; x = 0, 0·1 and 0·5) compositions are prepared using B₂O₃ flux. Powder XRD studies showed them all to belong to the tetragonal system with space group I $ \bar 4 $ \bar 4 2d. Their infrared spectra exhibit characteristic vibrational bands of BO₄ tetrahedron. The room temperature powder electron spin resonance (ESR) spectrum of copper metaborate gave a single peak at g ∼ 2·15. The diffuse reflectance spectra (DRS) of Cu_1−x M _x B₂O₄ (M = Ni, Co and Mn; x = 0, 0·1 and 0·5) are consistent with ligand to metal ion charge transfer and square planar symmetry of Cu²⁺ ion. The ligand field parameters Dq _xy , D _s and D _t are obtained.