DIFFERENCE BETWEEN CSMA/CD AND CSMA/CA:

CSMA/CD:
Carrier sense multiple access with collision detection (CSMA/CD) is one of the most popular access methods, with CSMA/CD, every host has equal access to the wire and can place data on the wire when the wire is free from traffic. If a host wishes to place data on the wire, it will “sense” the wire and determine whether there is a signal already on the wire. If there is, the host will wait to transmit the data; if the wire is free, the host will send the data, as shown in Figure 1.


Figure 1: A host "sensing" the wire to see if it is free of traffic.

The problem with the process just described is that, if there are two systems on the wire that “sense” the wire at the same time to see if the wire is free, they will both send data out at the same time if the wire is free. When the two pieces of data are sent out on the wire at the same time, they will collide with one another, and the data will be destroyed. If the data is destroyed in transit, the data will need to be retransmitted. Consequently, after a collision, each host will wait a variable length of time before retransmitting the data (they don’t want the data to collide again), thereby preventing a collision the second time. When a system determines that the data has collided and then retransmits the data, that is known as collision detection.

To summarize, CSMA/CD provides that before a host sends data on the network, it will “sense” (CS) the wire to ensure that the wire is free of traffic. Multiple systems have equal access to the wire (MA), and if there is a collision, a host will detect that collision (CD) and retransmit the data.

CSMA/CA:

Carrier sense multiple access with collision avoidance (CSMA/CA) is not as popular as CSMA/CD and for good reason. With CSMA/CA, before a host sends data on the wire, it will “sense” the wire as well to see if the wire is free of signals. If the wire is free, it will try to “avoid” a collision by sending a piece of “dummy” data on the wire first to see whether it collides with any other data. If it does not collide, the host in effect assumes “If my dummy data did not collide, then the real data will not collide,” and it submits the real data on the wire.

Comments

PRIMARY SECONDARY AND TERTIARY FREQUENCY CONTROL IN POWER SYSTEMS

Primary, Secondary and Tertiary Frequency Control in Power Systems Author: Engr. Aneel Kumar Keywords: frequency control, primary frequency control, automatic generation control (AGC), tertiary control, load-frequency control, grid stability. Frequency control keeps the power grid stable by balancing generation and load. When generation and demand drift apart, system frequency moves away from its nominal value (50 or 60 Hz). Grids rely on three hierarchical control layers — Primary , Secondary (AGC), and Tertiary — to arrest frequency deviation, restore the set-point and optimize generation dispatch. Related: Power System Stability — causes & mitigation Overview of primary, secondary and tertiary frequency control in power systems. ⚡ Primary Frequency Control (Droop Control) Primary control is a fast, local response implemented by generator governors (dro...

CASCADED TRANSFORMERS METHOD FOR GENERATING AC HIGH VOLTAGE

High-Frequency AC High Voltage Generation Using Cascaded Transformers Author: Engr. Aneel Kumar Figure 1: Infographic representation of cascaded transformers method for generating high AC voltages. Introduction In high voltage engineering , generating very high alternating current (AC) voltages is essential for testing equipment like insulators, circuit breakers, power cables, and other apparatus. One common and effective method for producing such voltages is the cascaded transformers method . This technique uses a series connection of specially designed test transformers , where the secondary of one transformer feeds the primary of the next. In this way, voltages are built up step by step, achieving levels in the range of hundreds of kilovolts (kV) or even megavolts (MV). Working Principle The principle of cascaded connection relies on the fact that each...

Advantages of Per Unit System in Power System Analysis | Electrical Engineering

Advantages of Per Unit System in Power System Analysis In electrical power engineering, the per unit (p.u.) system is one of the most widely used techniques for analyzing and modeling power systems. It is a method of expressing electrical quantities — such as voltage, current, power, and impedance — as fractions of chosen base values rather than their actual numerical magnitudes. This normalization technique provides a universal language for system calculations, minimizing errors, simplifying transformer modeling, and enabling consistency across multiple voltage levels. Because of these benefits, the per unit system is essential in fault analysis, load flow studies, transformer testing, and short-circuit calculations . ⚡ What is the Per Unit System? The per unit system is defined as: Q u a n t i t y ( p u ) = A c t u a l V a l u e B a s e V a l u e Quantity_{(pu)} = \dfrac{Actual \ Value}{Base \ Value} Q u an t i t y ( p u ) = B a se ...

ADVANTAGES OF INTERCONNECTED GRID SYSTEM

Interconnected Grid System: Working, Advantages, Disadvantages, and Comparison with Isolated Grids Author: Engr. Aneel Kumar Figure 1: Infographic showing key advantages of an interconnected grid system. Introduction An interconnected grid system refers to a network of multiple power generation sources, transmission lines, substations, and distribution systems that are linked across regions, states, or even countries. Unlike an isolated grid (or islanded grid) which operates independently, an interconnected grid allows electricity to flow between interconnected nodes, enabling numerous benefits and some trade-offs. In today’s energy landscape—where demand, renewable generation, reliability, and cost pressure are all increasing—understanding how an interconnected grid works, what factors are essential, and what its advantages and disadvantages are is critical for utility planners, reg...

ADVANTAGES AND DISADVANTAGES OF CORONA EFFECT IN TRANSMISSION LINES | ELECTRICAL ENGINEERING GUIDE

Advantages and Disadvantages of Corona Effect in Power Systems In high-voltage overhead transmission lines , the corona effect plays a critical role in system performance. Corona occurs when the air around a conductor becomes ionized due to high electric stress. While often seen as a drawback because of power losses and interference , it also provides certain engineering benefits . This article explains the advantages and disadvantages of corona effect in detail, with examples relevant to modern electrical power systems. ✅ Advantages of Corona Effect Increase in Virtual Conductor Diameter Due to corona formation, the surrounding air becomes partially conductive, increasing the virtual diameter of the conductor. This reduces electrostatic stress between conductors and minimizes insulation breakdown risks. Related Reading: Electrostatic Fields in High Voltage Engineering Reduction of Transient Surges Corona acts like a natural cushion for sudden ...

DIFFERENCE BETWEEN GRID STATION AND SUB STATION

An electrical power substation is a conversion point between transmission level voltages (such as 138 KV) and distribution level voltages (such as 11 KV). A substation has one or more step-down transformers and serves a regional area such as part of a city or neighborhood. Substations are connected to each other by the transmission ring circuit. An electrical grid station is an interconnection point between two transmission ring circuits, often between two geographic regions. They might have a transformer, depending on the possibly different voltages, so that the voltage levels can be adjusted as needed. The interconnected network of grid stations is called the grid, and may ultimately represent an entire multi-state region. In this configuration, loss of a small section, such as loss of a power station, does not impact the grid as a whole, nor does it impact the more localized neighborhoods, as the grid simply shifts its power flow to compensate, giving the power station o...

THYRISTOR CONTROLLED SERIES COMPENSATOR TCSC

The basic Thyristor Controlled Series Capacitor scheme was proposed in 1986 by Vithayathil with others as a method of "rapid adjustment of network impedance". A TCSC can be defined as a capacitive reactance compensator which consists of a series capacitor bank shunted by a thyristor-controlled reactor in order to provide a smoothly variable series capacitive reactance. In a practical TCSC implementation, several such basic compensators may be connected in series to obtain the desired voltage rating and operating characteristics. However, the basic idea behind the TCSC scheme is to provide a continuously variable capacitor by means of partially canceling the effective compensating capacitance by the TCR. The basic conceptual TCSC module comprises a series capacitor, C, in parallel with a thyristor controlled reactor. Figure: Structure of TCSC PRINCIPLE OF OPERATION: A TCSC is a series-controlled capacitive reactance that can provide continuous control of power on t...

ENGINEERING ARTICLES

Search This Blog