Hybrid Transceiver Optimization for Multi-Hop Communications

Multi-hop communication with the aid of large-scale antenna arrays will play a vital role in future emergence communication systems. In this paper, we investigate amplify-and-forward based and multiple-input multiple-output assisted multi-hop communication, in which all nodes employ hybrid transceivers. Moreover, channel errors are taken into account in our hybrid transceiver design. Based on the matrix-monotonic optimization framework, the optimal structures of the robust hybrid transceivers are derived. By utilizing these optimal structures, the optimizations of analog transceivers and digital transceivers can be separated without loss of optimality. This fact greatly simplifies the joint optimization of analog and digital transceivers. Since the optimization of analog transceivers under unit-modulus constraints is non-convex, a projection type algorithm is proposed for analog transceiver optimization to overcome this difficulty. Based on the derived analog transceivers, the optimal digital transceivers can then be derived using matrix-monotonic optimization. Numeral results obtained demonstrate the performance advantages of the proposed hybrid transceiver designs over other existing solutions.Comment: 32 pages, 6 figures. This manuscript has been submitted to IEEE Journal on Selected Areas in Communications (special issue on Multiple Antenna Technologies for Beyond 5G

catena-Poly[[bis­(nitrato-κO)cadmium]bis­[μ-1,3-bis­[(1H-1,2,4-triazol-1-yl)meth­yl]benzene-κ2 N 4:N 4′]]

In the title compound, [Cd(NO3)2(C12H12N6)2]n, the CdII cation is located on an inversion center and is six-coordinated by four N atoms from four 1,3-bis­[(1H-1,2,4-triazol-1-yl)meth­yl]benzene (L) ligands and two O atoms from two nitrate anions in a slightly distorted octa­hedral geometry. The ligands link different CdII ions into a ribbon-like structure along [001]. Two O atoms of the nitrate anion are disordered over two sets of sites with site occupancies of 0.575 (8) and 0.425 (8)

Bethe ansatz for an AdS/CFT open spin chain with non-diagonal boundaries

We consider the integrable open-chain transfer matrix corresponding to a Y=0 brane at one boundary, and a Y_theta=0 brane (rotated with the respect to the former by an angle theta) at the other boundary. We determine the exact eigenvalues of this transfer matrix in terms of solutions of a corresponding set of Bethe equations.Comment: 25 pages; v2: reference added; v3: minor revisions, form accepted by journa