This paper reports on the synchronization performance of a hardware implemented network time protocol (HwNTP) module for digitized radio over fiber (DROF) system. In the experiments, the HwNTP client is synchronized with the HwNTP server via an asynchronous packet network, and provides highly accurate time and frequency references compared to software based NTP. The achieved accuracy over a commercial Ethernet service is sufficient to satisfy the DROF requirements.
As a compensation of Gaussian approximation applied to an impulsive noise for estimating its disturbance effects on communication systems, impulsiveness correction factor (ICF) has been developed. ICF is defined by the ratio of the interfering noise power to the Gaussian noise power that causes the same degradation in bit error probability (BEP). Amplitude probability distribution (APD) of an interfering noise is also known to have a good correlation to the BEP of disturbed systems. In this paper, relation between ICF and APD is discussed to develop a simple expression.
Mutually orthogonal periodic complementary sequence sets (MOPCSS) and their application are investigated in this letter. A new generator for quadriphase MOPCSSs is first presented, which uses a unitary-like matrix as a seed matrix. Next, a new design of pilot sequences using MOPCSSs for multiple-input and multiple-output (MIMO) single-carrier block transmission (SCBT) systems is given. Later on, an optimized periodic Golay correlator is proposed to efficiently implement the least square MIMO channel estimation. Finally, the optimal performance of the channel estimation is verified via simulation.
In this paper, sub-band technique to reduce the effect of antenna pattern distortion is proposed. In the proposed scheme, received wideband signal is divided into several frequency bands and DOA is estimated in the respective frequency bands. By averaging the estimated results, the effect of antenna pattern distortion will be reduced. Numerical results shows that the DOA estimation accuracy is improved by the proposed sub-band signal processing.
We propose a network coding aware instantaneous recovery scheme based on optimal traffic splitting that determines a set of K+1 disjoint paths which minimizes the total cost of network resource utilization. A traffic demand is equally split into K equal parts and sent along K disjoint paths, and the K+1th path is provided to carry simultaneously the network coded traffic of all the equally divided traffic for instantaneous recovery upon occurrence of failure.
This letter presents a bifurcation analysis of the class-E inverter for switching-pattern derivations. The transition conditions of switching patterns are the same as the bifurcation condition of the border-collision bifurcation or the grazing bifurcation. Therefore, the switching-pattern distribution maps for wide parameter region can be obtained by applying the analytical algorithm of bifurcation-curve derivations.
A wideband dual-polarized small antenna is proposed using a crossed tapered slot antenna. This antenna is small and lightweight. An antenna geometry for easy fabrication is also provided by combining two TSAs with slits and a slot on each substrates.
In this paper, effect of array configuration, directivity of element, control method, and losses in feeding cables on SINR characteristics of the adaptive array on a vehicle is examined. As the result, in most cases, it was clarified that X-type feeding network was the most excellent in feeding network, and MMSE had the most excellent performance in control methods.
Large many-core parallel applications become sensitive to communication latencies, suggesting the need for low-latency networks in high-performance computing systems. Switch delay dominates network latencies. To reduce the network latencies, we exploit routing cache on a switch. Routing decision based on off-chip CAM (Content Addressable Memory)-based table lookup imposes a significant delay, however, using on-chip small routing cache can bypass it when it hits. Our simulation results show that the only 256-entry routing cache hits 98% on over 4k-host systems with the matrix-transpose traffic, and the 1024-entry routing cache improves not only up to 16% of packet latency but also up to 18% of network throughput.