While designing the communication system, an engineer generally faces several constraints or limitations. So today we are going to discuss these fundamental Limitations of communication systems.
Generally, These limitations are as per below:
| Fundamental Limitations of Communication System | |
|---|---|
| 1. | Noise Limitation |
| 2. | Bandwidth Limitation |
| 3. | Equipment Limitation |
We will discuss these limitations in brief one by one.
1. Noise Limitation
The noise may be defined as an unwanted form of energy which tend to interfere with the transmission and reception of the desired signals in a communication system.
The noise cannot be eliminated completely. However, the effect of noise on desired signals can be minimized with the help of several techniques.
Noise can be classified into two broad categories depending on its source:
- External noise and
- Internal noise.
External noise is a type of noise whose sources are external to a communication system. Examples of external noise are atmospheric noise, galactic noise, and industrial noise.
Internal noise is a type of noise whose sources are internal to a communication system. Examples of internal noise are thermal noise and shot noise. This type of noise is inevitable in every communication system and forms a basic limitation on the transmission and reception of signals.
In fact, the noise limits our ability to identify the intended or desired message correctly and thus limits information transmission.
Typical noise variations are measured in microvolts.
If the signal variations are quite large in comparison, then the effect of noise is very small and may be ignored.
In fact, in many practical communication systems, the effect of noise is generally unnoticeable. However, in long-distance communication systems operating with a limited amount of signal power. the signal may be as small as the noise or even smaller than the noise.
Thus, in such cases, the presence of noise severally limits the capabilities of a communication system.
Also Read: Noise In Communication System
2. Bandwidth Limitation
In addition to noise, bandwidth limitation is another major constraint in a communication system.
The frequency range or the band of frequency needed for a particular given transmission is known as bandwidth. This band of frequencies required for a particular transmission is also called a channel.
This band of frequencies or bandwidth for a particular transmission is always allocated by some International regulatory agencies.
This type of regulation is essential to avoid interference among the signals having the same frequency, But, for a given transmission, this allocated bandwidth may not be sufficient to convey the entire information.
In fact, the information theory states that the greater is the transmission bandwidth of a communication system, the more is the information that can be transmitted.
Let us consider a simple example. Suppose one is listening to music on an AM radio. The complete amount of information available to the human ear is contained in a frequency range up to 15 kHz, i.e., musical information extends up to a frequency of 15 kHz. However, in AM radio the maximum modulating frequency is restricted up to 5 kHz and hence the maximum bandwidth of AM transmission is 10 KHz. Therefore, an AM radio receiver cannot reproduce all the information contained in the music because this will require a bandwidth of 30 kHz.
On the other hand, the bandwidth allocated to an FM transmission is about 200 kHz. Thus an FM receiver can easily reproduce the transmitted information without any distortion. This means that an FM system has a better fidelity than an AM system. Also, it may be observed in common life that one prefers to listen to an FM radio than an AM radio.
Thus, we can conclude that bandwidth is a major fundamental limitation of a communication system.
3. Equipment Limitation
The noise and bandwidth limitations dictate theoretically what can or cannot be achieved in terms of performance in a communication system.
However, this theoretical limit may not be realized in a practical system due to equipment limitations
For example, the theory might require a band-pass filter with a quality factor of 100 at a center frequency of 1 kHz. Such a filter cannot be realized in practice. Even if a filter with nearly identical characteristics is built, the cost may exceed what the user of the communication system wants to pay.
Thus equipment limitation is another major problem in a communication system.
