Performance of adaptive mobile terminal selection schemes for collaborative MMSE linear MIMO detection

This paper considers a multi-machine control system using power line communication (PLC). The signal-to-noise ratio (SNR) of PLC channels has cyclostationary features synchronous to the mains voltage. As a promising candidate of the multiple access scheme for the system, this paper proposes a synchronous code division multiple access (SCDMA) scheme that uses mains voltage as its system clock. By using orthogonal codes, the communication performance of each code-channel is equalized, and the worst-case performance is improved

Distributed Cooperative Relaying Based on Space-Time Block Code: System Description and Measurement Campaign

In cooperative relaying, intermediate stations are required to enhance the end-to-end transmission performance. The performance of the cooperative relaying scheme has been investigated theoretically and via computer simulations. However, cooperative relaying using transmit diversity techniques in actual environments has not been investigated thus far. This paper presents an experimental system for distributed cooperative relaying using space-time block code and evaluations of its transmission performances in real propagation channels. To this end, four wireless stations-specifically, one source, two relays, and one destination-were developed using analog transceivers and field-programmable gate arrays for real-time digital signal processing. Sample timing and frequency synchronizations among the four wireless stations were established by using the received signals as a reference. The end-to-end error performance of distributed cooperative relaying was compared to those of noncooperative relaying schemes, and the performances of three relaying schemes were evaluated quasisimultaneously in terms of their cumulative distribution functions of the bit-error ratios (BERs). The experimental results indicated that the BER performance of the two-hop distributed cooperative relaying scheme was substantially superior to those of noncooperative two-hop relaying schemes, including a route diversity scheme

Optimal Transmission Scheduling for a Hybrid of Full- and Half-Duplex Relaying

Full-duplex relaying (FDR), i.e., simultaneous transmission and reception using the same frequency channel at a radio relay, can be used to achieve a spectral efficiency higher than that in the case of half-duplex relaying (HDR) if loop-back interference is well-managed. To achieve spectral efficiency that is higher than that achieved when using FDR and HDR separately, an optimal transmission-scheduling scheme for an FDR-HDR hybrid is proposed. The scheme is formulated as an optimization problem. The conditions required to achieve the maximum spectral efficiency are determined analytically. Numerical results confirm that the proposed scheme is superior to FDR and HDR

Dynamic Strength and Permanent Deformation of Saturated Sand

The undrained cyclic triaxial behavior of saturated sand has been studied using anisotropically consolidated specimens. The strength and deformation under various combinations of initial static and cyclic shear stresses were attempted to clarify. The cyclic strength was first discussed, and then, the residual shear strain was investigated related with effective stress ratio at the end of each stress cycle. Finally, an empirical model was proposed for evaluating the development of pore pressure and residual shear strain of saturated sand subjected to various initial static and subsequent cyclic shear stresses