A. Emleh

Measurement of buffer requirement trends for real time traffic over TCP

Conceptionally the User Datagram Protocol (UDP) should be well-suited for real-time applications, e.g., for Voice over IP (VoIP). However, many such applications, e.g., Skype, use the Transmission Control Protocol (TCP) either as a primary protocol or as a backup protocol when UDP is blocked, despite TCPs flow control-related data delays. This paper proposes a technique for the estimation of the application buffer requirements of such TCP-based applications and the amount of data congestion in real-time TCP data streams. We apply this technique to data collected from a global network exchanging synthetic real-time traffic over TCP. Our results show that the buffering requirements vary widely with time and path but can be substantial in many cases.

Effects of LED lamps on the power-line communications channel

LED (Light Emitting Diode) lamps have recently come on to the market as energy efficient alternatives to incandescent light bulbs. Although energy effective, they inject conductive noise into the power-line system. This can have a detrimental effect on the power-line communications channel. This paper investigates these effects when LED lamps are seen as noise sources on the power line. It shows that there are two classes of LED lamps - depending on the noise generating electronics used as drivers for the light emitting diodes. Different driver electronics have different influences in different parts of the emission spectrum. It is shown that in the CENELEC band: (3kHz-150kHz) the interference level from LED lamps is significantly below the allowed maximum PLC signal levels. In the band 150kHz-30MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels and the SNR can be equal to zero, but only if the lamps have active power electronic converters.

The influence of fluorescent lamps with electronic ballast on the low voltage PLC network

The fluorescent lamps or fluorescent tubes are low pressure mercury-vapor gas-discharge lamps that use fluorescence to produce visible light. These lamps inject noise into the power-line communications channel. This can have a detrimental effect on the power-line communication system. In this paper we investigate the effects when the fluorescent lamps with electronic ballasts are seen as noise sources on the powerline channel. It is shown that in the CENELEC band: (3kHz-150kHz) the interference level from fluorescent lamps is significantly below the allowed maximum PLC signal levels. In the band 150kHz-30MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational method of the electronic ballast inside the fluorescent lamp is explained.

Received noise on powerline communications where the in-building wiring acts as an antenna

The powerline channel is considered as a challenging channel due to the heavy load and noise impairments. In this paper we investigate an important type of measurement with regards to the powerline communications channel, where the low voltage wiring inside a house is considered as a receiving antenna for interference. Several types of measurements are presented using the corresponding broadband PLC channel as a communication medium. Impulsive and interference noise play a major role in the contamination factors on a powerline channel. The results include the different measurements of noise in the frequency domain. Extensive tests and measurements have been used to ascertain which specific external interference, after filtering by the coupling circuit, does affect the entire PLC system being used in a house.

On mercury vapor lamps and their effect on the smart-grid plc channel

The mercury vapor lamp is the oldest high intensity discharge technology lamp that uses an electric arc, and comes in different shapes and designs. It creates a very bright light by using an arc through vaporized mercury in a high pressure tube. This lamp can cause unwanted interference to the smart-grid network or power line communications channel when connected to the channels wiring system. In this paper we investigate the negative effects that the mercury vapor lamps with electric ballast have on the smart-grid PLC channel. This can have a strong and negative effect when using the smart-grid PLC network to control the automatic switching of lamps in public places. The narrowband and broadband channels are investigated where the interference level from mercury vapor lamps is significantly below the allowed maximum PLC signal levels on the band: (3 kHz - 150 kHz), and competes with Electromagnetic Compatibility (EMC) levels on the 150 kHz - 30 MHz band. The mercury vapor lamp uses an electric ballast to connect to the powerline system. This connection is explained in detail.

The influence of high pressure sodium lamps on the power line communications channel

The high pressure sodium lamp is a high energy outdoor light source that belongs to the high intensity discharge lamp family. It comes in different shapes and requires a ballast to start it. The high pressure sodium lamp is a source of interference to the power line communications channel as it injects noise when connected to the 220V mains. This paper investigates the influence of the high pressure sodium lamp on the narrowband and broadband power line communications channel. It is shown that the frequency band: 3kHz-150kHz is not highly infected whereas in the band: 150kHz-30MHz, PLC signals compete with Electromagnetic Compatibility (EMC) levels.

Noise generated by modern lamps and the influence on the smart-grid communication network

The metal halide lamp is a high energy electric lamp that produces visible light by an electric arc tube and it is a type of high-intensity discharge (HID) that contains a fused quartz and mixture of gases. These lamps inject noise into the smart-grid power line communications (PLC) network. This can have a strong and negative effect when using the PLC system to control the automatic switching of lamps in public places. In this paper we investigate the effects when the metal halide lamps with electronic or electromagnetic ballasts are seen as noise sources on the smart-grid power line network. It is shown that in the CENELEC band: (3 kHz-150 kHz) the interference level from metal halide lamps is significantly below the allowed maximum PLC signal levels. In the band 150 kHz-30 MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational methods of the electronic and electromagnetic ballasts when connected to the metal halide lamps are explained.

Influence of LED tubes on the throughput of an indoor broadband PLC channel

This paper shows how Light Emitting Diode (LED) Tubes negatively influence the data rate throughput of an indoor broadband Power Line Communications (PLC) channel. This negative influence on the data rate is due to noise being generated by the lamps. Differential Mode measurements were done with two PLC modems communicating and then introducing LED lamps that add noise to the channel. Drops in data throughput rates were measured and compared to a clean (no noise) channel. A significant decrease (up to 50%) in throughput was observed which can have important implications for applications of PLC in the presence of LED Tubes.

An overview of colour LED & CFL lighting interference on the low voltage PLC network

Light sources are being competitive in the current market. Several types of these products have been widely used in the last two decades. They play a major role on the low voltage network as they produce and inject undesired noise onto the transmission lines of the PLC channel. This noise can be of a serious and negative effect when using the power line communications system to control the automatic switching of lamps in residential areas and public places. The main colour low energy indoor light sources that exist in the market, such as, LEDs and CFLs have been tested for the noise generation on the PLC channel and the results are analyzed and shown in this study. A mathematical analysis of LED bridge rectifier is introduced in this study.

Characterization of a power line cable for channel frequency response — Analysis and investigation

This paper focuses on the determination of the Channel Frequency Response (CFR) for a length of power cable which is crucial in determining the channel performance. The per-unit-length (PUL) parameters of a power line cable is used to calculate the CFR theoretically. This is verified by real world measurement. A new approach is introduced to model the PUL parameters. This work focus on characterizing a 1.5mm2 twin and earth (ribbon), 10-meter length cable. PUL parameters are estimated from measurements using an impedance analyzer. Further, the corresponding channel frequency response (CFR) is calculated using the developed equation. The accuracy of this investigation is being tested with a frequency range from 1 to 100 MHz. Numerical simulation results provided in this paper are in close agreement with the theoretical aspects of the CFR.