Single-input Single-output Schemes Research Articles

Performance of an OFDM STBC-MISO system in uplink terrestrial-satellite laser communication.

We propose a space-time block coded multiple input single output (STBC-MISO) terrestrial-satellite laser communication uplink system based on orthogonal frequency division multiplexing (OFDM) modulation. It further uses Málaga distribution to simulate near-ground turbulence. Considering the combined effects of the uplink light intensity scintillation, beam wander, and angle-of-arrival fluctuation, a closed expression of the terrestrial-satellite uplink bit error rate for the proposed system is derived. The simulation analyzes the influence of transmitting radius, receiving aperture, beam divergence, zenith angle, and signal-to-noise ratio on the system's error performance, and compares it with OFDM modulated single input single output (SISO) and differential phase-shift keying-modulated SISO schemes. Finally, the experimental data are verified by the Monte Carlo method. This research provides a theoretical basis for research on MISO terrestrial-satellite laser communication uplink system coding technology.

Energy efficiency of a per-hop relay selection scheme for sensor networks using cooperative MIMO

The energy efficiencies of cooperative Multi-Input Multi-Output (MIMO) schemes are analysed in the context of dense multi-hop wireless sensor networks. The framework of per-hop relay selection is employed, which decides on the next-hop relay based on a metric that captures the trade-off between the performance and the energy cost. Such a framework makes the analysis tractable and suggests a practical way to implement opportunistic cross-layer routing with physical layer adaptation. A few representative cooperative MIMO transmission schemes such as spatial multiplexing, Alamouti coding and selection diversity are analysed as well as an adaptive scheme that switches the transmission strategy based on channel conditions. Simulation results reveal that the cooperative MIMO schemes achieve significant performance enhancement over the Single-Input Single-Output (SISO) scheme when the circuit power consumption is small compared to the transmit power. However, when the circuit power consumption is not negligible compared to the transmit power, the cooperative MIMO may not be energy efficient in the cross-layer setting compared to the SISO scheme.

Time reversal of electromagnetic waves and telecommunication

Time reversal (TR) communication in various configurations (single input, single output (SISO); multiple inputs, single output (MISO); or multiple inputs, multiple outputs (MIMO)) is studied. In particular, we report an experimental demonstration of time reversal focusing with electromagnetic waves in a SISO scheme. An antenna transmits a 1 μs electromagnetic pulse at a central frequency of 2.45 GHz in a high‐Q cavity. Another antenna records the strongly reverberated signal. The time‐reversed wave is built and transmitted back by the same antenna acting now as a time reversal mirror. The wave is found to converge to its initial source and is compressed in time. The quality of focusing is determined by the frequency bandwidth and the spectral correlations of the field within the cavity. A spatial focusing of the compressed pulse is also shown. This experiment is the first step for a communication scheme based on time reversal. It would be very interesting for ultrawideband communication in complex media since TR would permit compensation for delay spreading. MISO and MIMO TR communications are discussed on the basis of small‐scale experiments with ultrasound. In particular, the binary error rate of the method is studied as a function of both data rate and external noise. A simple theoretical approach explains the results.