# What is intersymbol interference in optical communication?

## What is intersymbol interference in optical communication?

In telecommunication, intersymbol interference (ISI) is a form of distortion of a signal in which one symbol interferes with subsequent symbols. This is an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable.

What is cause of ISI problem in OFDM?

ISI is usually generated when transmitting in a multipath fading channel. In this kind of channel, multiple copies of the transmitted signal is received at different time intervals, which causes interference.

### Who was the first to solve the problem of intersymbol interference?

4. Who was the first to solve the problem of ISI? Explanation: Nyquist was the first to solve the problem of ISI. He overcome the problem of ISI while keeping the transmission bandwidth low.

What does ISI stands for in optical fiber communication?

1. Introduction. Inter-symbol interference (ISI) exists in the transmission of signals in communication systems. For example, optical communication systems need large output signal-to-noise ratio (SNR) and low bit error rate (BER).

#### Why is pulse shaping done?

In electronics and telecommunications, pulse shaping is the process of changing the waveform of transmitted pulses. Its purpose is to make the transmitted signal better suited to its purpose or the communication channel, typically by limiting the effective bandwidth of the transmission.

Why equalizer is used in communication?

In digital communications, the equalizer’s purpose is to reduce intersymbol interference to allow recovery of the transmit symbols. It may be a simple linear filter or a complex algorithm.

## What are the methods used to suppress the ISI?

The principle is to suppress the ISI in communication system by optimizing the equalizer tap of communication channel and calculating the reasonable multi-path component delay of channel.

How does cyclic prefix remove ISI?

To permanently eliminate this problem, the solution is to find a way where the ‘lost’ part of the symbol could be ‘recovered’. The one way to do this is by copying or duplicating an initial part of the symbol, and inserting the end of it. And it acts as Cyclic Prefix.

### What is ISI explain Nyquist’s first criteria for zero ISI?

Raised cosine response meets the Nyquist ISI criterion. Consecutive raised-cosine impulses demonstrate the zero ISI property between transmitted symbols at the sampling instants. At t=0 the middle pulse is at its maximum and the sum of other impulses is zero.

Can we eliminate ISI completely?

The ISI is unwanted and should be completely eliminated to get a clean output. The causes of ISI should also be resolved in order to lessen its effect. To view ISI in a mathematical form present in the receiver output, we can consider the receiver output.