Power line communications (PLC) allows data communications over conductors that are simultaneously used for transmission of electrical power.PLCs work by adding a modulated carrier signal, formed by superimposing data signal over low frequency power signal. Electrical signals transmit at 50 – 60 Hz, while the data signals transmit in the order of MHz.PLCs are also known as power line carrier, power line digital subscriber line (PDSL), or power line networking (PLN).Types of PLC:Narrowband PLC: They work at lower frequencies of 3-500KHz. Their data rates are low but have high range of several kilometres. They are used in the Smart Grid.Broadband ... Read More

Data rate refers to the speed of data transfer through a channel. It is generally computed in bits per second (bps). Higher data rates are expressed as Kbps ("Kilo" bits per second, i.e.1000 bps), Mbps ("Mega" bits per second, i.e.1000 Kbps), Gbps ("Giga" bits per second, i.e. 1000 Mbps) and Tbps ("Tera" bits per second, i.e. 1000 Gbps).One of the main objectives of data communications is to increase the data rate. There are three factors that determine the data rate of a channel:Bandwidth of the channelNumber of levels of signals that are usedNoise present in the channelData rate can be ... Read More

Fourier analysis is a method of representing general functions by approximate sum of simple trigonometric functions. The method is named after mathematician Jean Baptiste Joseph Fourier who formulated and proved the Fourier series. Fourier analysis is used in electronics, communications and acoustics.The Fourier series decomposes a periodic function as a sum of sine and cosine components as expressed below:where, g(t) is the periodic functionT is the time periodf is the fundamental frequency expressed as 1/Tan is the sine amplitude of the nth harmonicbn is the cosine amplitude of the nth harmonicc is a constantThe values of an, bn and c ... Read More

Asymptotic AnalysisUsing asymptotic analysis, we can get an idea about the performance of the algorithm based on the input size. We should not calculate the exact running time, but we should find the relation between the running time and the input size. We should follow the running time when the size of input is increased.For the space complexity, our goal is to get the relation or function that how much space in the main memory is occupied to complete the algorithm.Asymptotic BehaviorFor a function f(n) the asymptotic behavior is the growth of f(n) as n gets large. Small input values ... Read More

Ethernet is a set of technologies and protocols that are used primarily in LANs. The performance of Ethernet is analysed by computing the efficiency of the channel under different load conditions.Let us assume an Ethernet network has k stations and each station transmits with a probability p during a contention slot. Let A be the probability that some station acquires the channel. A is calculated as −A = kp (1−p)kpThe value of A is maximized at p = 1/k. If there can be innumerable stations connected to the Ethernet network, i.e. k → ∞, the maximum value of A will ... Read More

The logical link control (LLC) is the upper sublayer of the data link layer of the open system interconnections (OSI) reference model for data transmission. It acts act an interface between the network layer and the medium access control (MAC) sublayer of the data link layer.The LLC sublayer is mainly used for its multiplexing property. It allows several network protocols to operate simultaneously within a multipoint network over the same network medium.LLC Layer in the OSI ModelThe Open System Interconnections (OSI) model is a 7 – layered networking framework that conceptualizes how communications should be done between heterogeneous systems. The ... Read More

Organizationally unique identifier (OUI) refers to a 24-bit number assigned to a manufacturer or a vendor of a network device or station. They are globally unique identifiers assigned by the Institute of Electrical and Electronics Engineers (IEEE) Registration Authority.OUI are typically used for uniquely identifying a particular device connected to the computer network through derived identifiers like the Medium Access Control (MAC) addresses. MAC addresses are of 6 octets ( 48-bits ). Among these, the first three octets of the addresses constitutes the OUI.A 3-octet OUI is generally represented in hexadecimal notation separated by dashes (for example, 1F – 9E ... Read More

Broadcasting in computer network is a group communication, where a sender sends data to receivers simultaneously. This is an all − to − all communication model where each sending device transmits data to all other devices in the network domain.The ways of operation of broadcasting may be −A high level operation in a program, like broadcasting in Message Passing Interface.A low level networking operation, like broadcasting on Ethernet.Broadcasting is shown in the following figure −Advantages of BroadcastingBroadcast helps to attain economies of scale when a common data stream needs to be delivered to all, by minimizing the communication and processing ... Read More

Multicasting in computer network is a group communication, where a sender(s) send data to multiple receivers simultaneously. It supports one – to – many and many – to – many data transmission across LANs or WANs. Through the process of multicasting, the communication and processing overhead of sending the same data packet or data frame in minimized.Ethernet MulticastEthernet multicast constitutes multicasting at the data link layer of the OSI model for Ethernet networks. Ethernet frames for multicasting are identified by a 1 bit in the LSB (least significant bit) of the first byte of the destination address.IP MulticastIP multicast provides ... Read More

Classic Ethernet is the original form of Ethernet used primarily in LANs. It provides data rates between 3 to 10 Mbps.It operates both in the physical layer and in the MAC sublayer of the OSI model. In the physical layer, the features of the cables and networks are considered. In MAC sublayer, the frame formats for the Ethernet data frame are laid down.Classic Ethernet was first standardized in 1980s as IEEE 802.3 standard.Frame Format of Classic EthernetClassic Ethernet frames can be either of Ethernet (DIX) or of IEEE 802.3 standard. The frames of the two standards are very similar except ... Read More