About NS3 Simulation Projects

A photovoltaic (PV) system has been widely deployed in residential areas to reduce energy cost. However, it is not monitored in detail or managed in a user-friendly manner in many cases. Therefore, a PV monitoring system needs to provide both detailed monitoring of each PV module and a user-friendly way of access to the monitored data. In addition, the PV monitoring system needs to be low-cost to be widely deployed. To achieve these needs, this paper proposes a user-friendly PV monitoring system based on a low-cost power line communication (PLC).

For cost reduction, the PLC module is developed without a communication modem. For detailed monitoring, the PLC modules are installed at each PV module; the data logger aggregates the monitored data of each PV module and the PV inverter. For userfriendly access, a smart app is used to show the aggregated data graphically. In the field test, the developed PV monitoring system is installed at a real PV system composed of sixteen 400 W PV module; users can figure out the status of the whole PV system through a smart device. This scheme is expected to reduce energy cost in residential areas by maintaining a PV system performance.

This paper presents an evaluation of Doppler Shift and Doppler Rate for the communication HEO satellites. A method for Doppler shift compensation is consideredwhich allows increasing channel capacity.

In a cellular network, connections between the Base Station (BS) and Mobile Stations (MS) may fail when the channel is in a deep fade. Shadow fading is large-scale fading which can cause significant received power loss for a wide area. This will lead to lost connections and/or packet loss which is harmful to mobile users, especially to those who are using real-time applications such as video conferencing. Cooperative communication is an efficient way to reduce outage and provide better Quality of Service (QoS) support for delay sensitive applications. A third station, which is often referred as a relay, can be used to forward signals between the BS and the MS.

This paper focuses on a study of the performance of relay deployments under correlated shadow fading. We consider the downlink direction in a single cell deployment, for which the shadowing effect is modeled as an angle and distance based correlated shadowing. The received signal-to- noise ratio (SNR) is then calculated by assuming jointly Gaussian shadow fading at the MS. Simulation results show channel variations over time with fixed user speed under different relay deployments. These results demonstrate that a modest number of relays can improve the performance of real-time applications significantly.

This paper proposes a novel design of an optical wireless communications (OWC) receiver using a solar panel as a photodetector. The proposed system is capable of simultaneous data transmission and energy harvesting. The solar panel can convert a modulated light signal into an electrical signal without any external power requirements. Furthermore, the direct current (DC) component of the modulated light can be harvested in the proposed receiver. The generated energy can potentially be used to power a user terminal or at least to prolong its operation time.

The current work discusses the various parameters which need to be considered in the design of a system using a solar panel for simultaneous communication and energy harvesting. The presented theory is supported with an experimental implementation of orthogonal frequency division multiplexing (OFDM), thus, proving the validity of the analysis and demonstrating the feasibility of the proposed receiver. Using the propounded system, acommunication link with a data rate of 11.84 Mbps is established for a received optical signal with a peak-to-peak amplitude of 0.7 × 10^-3 W/cm².

A novel broadband chaos-based coherent binary phase shift keying (BPSK) communication system is proposed and it is demonstrated that its theoretical probability of error expression matches that of a conventional narrowband BPSK system. The result is confirmed with the corresponding empirical bit error rate (BER) simulation.

Most importantly, it is shown that the proposed system outperforms the chaotic communication systems in terms of BER while also being more practicable. The proposedsystem thus holds high promise as the chaotic communication systems pose implementation difficulties, lack robust synchronisation techniques and are generally considered of academic interest only.

In this paper an assessment concerning the potential impact of interference caused by transmissions of wireless avionics intra-communication systems onto aeronautical radio altimeter operating co-frequency is presented. The radio altimeter model utilized for the assessment accounts for realistic scattering and antenna characteristics to describe echo signals returned by the Earth surface. It includes a detailed description of the signal processing and detection stages allowing for a comprehensive analysis of the interference impact.

The interference of wireless avionics intra-communication transmissions is modeled by offset quadrature phase-shift keying modulated signals which are added to radio altimeter receive antenna output signal. The assessment covers a broad range of potential interference scenarios. It includes a detailed analysis of the spectral characteristics of wireless avionics intra-communication signals observed in the radio altimeter detection stage and an evaluation of their impact onto the altitude detection reliability.

This paper describes a method for monitoring multiple loads from the front-end of a wireless power transfer system without using any wireless communication systems. A mathematical approach based on scanning the frequency around the resonant frequency has been developed for deriving the load conditions.

The proposal requires only information of the input voltage and current only, therefore eliminating the requirements of using wireless communication systems for feedback control. The proposal has been practically confirmed in hardware prototype with acceptable results.

In high-speed railway communication (HSRC) systems, ensuring the continuity of on-going services is one of the toughest challenges, for the existence of influential factors such as frequent handoff event, short time window for handoff, and severe channel distortion, etc. In HSRC systems with limited resources, admission control (AC) is one of the most efficient methods to overcome this challenge and guarantee the requirement of service dropping probability (SDP). However, now it still lacks of recognized AC scheme that can be used in HSRC systems. In this paper, a novel AC scheme is proposed to HSRC systems, where resource reservation algorithm and resource preemption model are developed together to reduce the SDP.

First, the main reasons of on-going service dropping related to AC scheme are analyzed, which include frequent adjustment of services’ modulation-and-coding-scheme (MCS) and continual handoff events. Second, an adaptive resource reservation algorithm is proposed to optimize the amount of reserved bandwidth for ongoing services, where the effect of MCS change at physical-layer and the characteristics of HSRC are both taken into account. Third, considering the effect of resource preemption on on-going services, a resource preemption model is developed to further obtain the available bandwidth resources. Then, according to the above works, the AC scheme is proposed to optimize the SDP performance. Finally, simulation results are presented to demonstrate the effectiveness of the proposed AC scheme.

Development of the theory and technology of the small element antenna arrays is one of the research areas of the Department of Technical Electromagnetics and Radio communication Systems since 2006. The research is focused on the improvement of the mobile communication systems.

Curvilinear antenna arrays are proposed that comprise antenna elements with controllable polarization of radiation, which are located along the ellipse arc. The potential emitting properties of such antenna arrays have been estimated. The adaptive beamforming algorithm with the necessary directional characteristics and controllable polarization of radiation is presented.

Recently proposed multiple input multiple output radars based on matrix completion (MIMO-MC) employ sparse sampling to reduce the amount of data forwarded to the radar fusion center, and as such enable savings in communication power and bandwidth. This paper proposes designs that optimize the sharing of spectrum between MIMO-MC radars and MIMO communication systems, so that the latter interferes minimally with the former.

First, the communication system transmit covariance matrix is designed to minimize the effective interference power (EIP) at the radar receiver, while maintaining certain average capacity and transmit power for the communication system. Two approaches are proposed, namely a noncooperative and a cooperative approach, with the latter being applicable when the radar sampling scheme is known at the communication system. Second, a joint design of the communication transmit covariance matrix and the MIMO-MC radar sampling scheme is proposed, which achieves even further EIP reduction.