Some Networked Devices Improve The Channel By Compressing The Data They Send. Most Modems Use This Feature. 

Network Throughput: If The Size Of A File, For Example, 64 KB, Can Be Reduced by Compression, the time required for transfer is reduced.

This can be hidden from the user, so a compressed file can be transferred significantly faster than expected. Because this ‘hidden’ compression cannot be easily disabled, a file that cannot compress must be used to measure throughput by transferring files and scheduling transfer time. Pre-compressed files, such as zip files, are often used.

Assuming that it is impossible to compress the data to transfer a 64 KB file over a 64 kbps transfer channel, the theoretical time it takes is 8.192 seconds. This is the minimum transfer time, but it takes longer in practice. This is due to the overhead effect of formatting the data in the agreed state.

Therefore, both sides of the relationship consistently view the data.

Network Throughput

At least two issues with compressing files are not immediately apparent.

1. The throughput of the network that performs the compression does not improve with compression. From a bottom-up perspective (server to client), compression enhances throughput. This is because the content of the information increases with compression for the same amount of information transmitted.

2. Compressing files in client and server systems requires more processor resources. Currently, the server compresses the files using its processor, which is false. The client also decompresses the files after receiving them.
This can be considered one of the necessary costs (for server and client systems) to increase end-to-end throughput (although throughput for the same network does not change).

What is operational capacity?

A network’s throughput can be measured using tools available on different operating systems. This page explains how these instruments are set up and the issues associated with these measurements.

In measuring network throughput, people often want to know the maximum data throughput in a communication link or network access in bits per second.

A common way to measure this quantity is to transfer a large file from one system to another and calculate the time required to complete the transfer or copy the file.

Operating power is then obtained by dividing the file size into megabits per second, kilobits per second, or bits per second.

Unfortunately, the results of such an experiment are in the range of good throughput, which is usually less than the maximum throughput given in theory. This leads people to think that their communication link is not working properly.

 In addition to transmission overheads, including downtime, TCP receiving window size, and system constraints, there are many overheads in goodput, which means that the calculated goodput does not represent the maximum available throughput.

Typically, people use abbreviations that are often used interchangeably. For file sizes, they usually use ’64k ‘instead of ’64kilobytes’ or ‘100meg’ instead of ‘100megabytes’.

 When it comes to the bit rate, use the terms throughput, bandwidth, and speed to indicate the speed of the circuit as ’64k’ or ‘2meg’, meaning a circuit at 64 kbps or two megabits per second. They give. However, a 64k circuit cannot transfer a 64k file in one second.

 This may not be obvious to people unfamiliar with telecommunications and computing, as they sometimes make mistakes.

Overheads and data formats

Most people use the serial link, which is also called the ‘asynchronous start-stop’ or ‘asynchronous’ link. If you use a modem externally connected to your home or office computer, your communication link may be established through an asynchronous serial connection.

This link’s advantage is that it is simple and can be implemented using only three wires: send, receive, and ground signal (standard signal).

 In the RS-232 protocol, bit ‘0’ has a negative voltage relative to the ground voltage, and bit ‘1’ has a positive voltage relative to the ground voltage. An inactive RS232 signal has a negative voltage.

So, any of the above descriptions about bits ‘0’ and ‘1’ are upside down here.

The starting bit of each byte has an upward voltage, indicating that the next bit is the first bit of serial data.

Asynchronous serial data at the TTL level ‘0’ at high voltage and ‘1’. A TTL / RS232 converter handles TTL level data, usually a maxim chip, such as the MAX232, which also inverts and changes the data level.

All signals inside a device are equipped with an RS232 connection and usually have an internal TTL level (0 and 5 volts or 0 and 3.3 volts or 0 and 3 volts). Converting to either RS232 is the last step in output data or the first, which is what input data does.

In fact, more items, such as the one-bit transfer rate, the number of bits per character, the parity bit, and the number of stop bits (meaning the end of a character), are agreed upon to advance the transfer.

For example, the agreed feature 9600-8-E-2 means that the channel has a transfer rate of 9600 bits per second, with 8 bits per character, even balance bit, and two stop bits.

These specifications in serial connections are usually set to 9600-8-N-1 (9600 bits per second, 8 bits per character, no balance bit, and one stop bit).

A total of 10 bits are transmitted to send each 8-bit character (one start bit, 8 data bits, and one stop bit), which means 25% overhead.

Therefore, an asynchronous serial link at 9600 bits per second (1200 bytes per second) does not transmit data at the same speed.

This situation can get worse. If a balanced bit and two stop bits are used, the overhead of each 8-bit character will be 4 bits (one start bit, balance bit, and 2twostop bits), equivalent to a 50% overhead.

In this case, a channel with a speed of 9600 bits per second can transmit 12,600 bytes per second (equivalent to 800 bytes per second).

Transfer speeds in asynchronous serial relationships are typically supported up to 230.4 kbps.

If the balance bit is not specified in the channel settings and a stop bit is used, the transfer rate will be 23.04 KB per second.

The advantage of the asynchronous serial connection is its simplicity. One disadvantage is its low efficiency in transportation. We can overcome this by using a simultaneous interface.

In this type of interface, a clock signal is added via a separate wire, and the bits are transmitted according to the clock.

The interface no longer pays attention to each character’s start and stop bits; however, a mechanism is needed to ensure that the sending and receiving clocks are synchronous.

For this purpose, the data is divided into frames of different characters with the help of known separators.