Two end-users which have symmetric traffic requirements in terms of data rate are considered. They exchange information in Rayleigh flat-fading channels and multiple serial half-duplex relay nodes are employed to extend the communication coverage and assist the bidirectional communication between them using the analog network coding( ANC) protocol. With the objective of minimizing the sum transmit energy at the required data rate c,the optimal relay positioning and power allocation problem is firstly investigated and then the sub-optimal solutions for a two-relay channel are proposed,due to no close-form optimal solution. Furthermore,a sub-optimal scheme of relay positioning and power allocation,called equal-distance equal-transmit-power( EDEP) for an arbitrary Nrelay channel,N > 1 is proposed. Simulation results demonstrate a consistence with our proposed scheme.
This paper describes a quantum switching architecture for nearest neighbor coupling. An efficient quantum shear sorting （QSS） algorithm is used to reduce the number of time steps. For the QSS algorithm, the running complexity of the quantum switching architecture is polynomial in time with the nearest neighbor coupling and the implementation is less complex. The result shows that improved switching is extremely simple to implement using existing quantum computer candidates.
We present a scheme for probabilistic transformation of special quantum states assisted by auxiliary qubits.In our scheme,if quantum states can be rewritten in a particular form,it is possible to transform such states into other states using lowerdimensional unitary operations that can be more easily realized in physical experiments.Furthermore,as an important application,we propose a generalized scheme that helps construct faithful quantum channels via various probabilistic channels when considering the existence of nonmaximally-entangled states.
We present a new scheme for investigating the usefulness of non-maximally entangled states for multi-party quantum state shar-ing in a simple and elegant manner.In our scheme,the sender,Alice shares n various probabilistic channels composed of non-maximally entangled states with n agents in a network.Our protocol involves only Bell-basis measurements,single qubit measurements,and a two-qubit unitary transformation operated by free optional agents.Our scheme is a more convenient realiza-tion because no other multipartite joint measurements are needed.Furthermore,in our scheme various probabilistic channels lessen the requirement for quantum channels,which makes it more practical for physical implementation.
