Serial vs. Parallel Transmission: Understanding the Key Differences

This page describes the difference between Serial Transmission and Parallel Transmission. There are two ways one can transmit binary data: serial and parallel.

Serial Transmission

In Serial Transmission, each bit is transmitted one after the other. For example, let’s say we want to transmit the letter ‘M’, which has an ASCII value of (msb)1,0,0,1,1,0,1(lsb). With serial transmission, this will be transmitted 1 bit at a time.

Here, the LSB (Least Significant Bit) is transmitted first, while the MSB (Most Significant Bit) is transmitted at the end. As the transmission is sequential, it takes a longer time to transfer all the data. Serial transmission is generally preferred for long-distance applications.

There are ways to convert from parallel to serial and vice versa, depending on the need. The shift register circuit is used to convert from serial to parallel and from parallel to serial format.

Serial Data Speed

Data rate (bps) = 1 / T_b

Where T_b is the time duration of 1 bit. If the bit duration is 2ms, then the data rate is:

$1 / (2 \times 10^{-3}) = 500$ bps

Baud Rate

Baud rate is defined as the number of signalling elements (symbols) in a given unit of time (e.g., 1 second).

Parallel Transmission

In parallel transmission, all the data bits are transmitted simultaneously from one place to another, using either a latch, a flip-flop, a bus, or a parallel connector, as per the need or application. Here, the speed of data transfer is very fast, but the distance is limited.

For long-distance communication, it requires more wires (one per bit) and hence is not practical due to the increased cost.

Serial vs. Parallel Transmission: Key Differences

The following table summarizes the important differences between serial and parallel transmission types: