How does signal-to-noise ratio affect the performance and reliability of wireless networks?

2 What are the sources of noise?

Noise is any unwanted signal that interferes with the desired signal in a wireless channel. This can come from various sources, such as thermal noise, which is the random fluctuations of electric current in the circuitry of the transmitter, receiver, and antenna caused by thermal agitation of electrons. Additionally, atmospheric noise is the natural electromagnetic radiation from the sun, stars, lightning, and other phenomena in the atmosphere. Man-made noise is artificial electromagnetic radiation from other devices like radios, TVs, computers, microwaves, and power lines that use the same or adjacent frequency bands as the wireless network. Finally, multipath noise is the reflection, refraction, diffraction, and scattering of the signal by objects in the environment which creates multiple copies of the signal that arrive at different times and angles at the receiver.

3 How to measure SNR?

SNR is usually expressed in decibels (dB), which is a logarithmic scale that compares the ratio of two power levels. To calculate SNR in dB, you need to know the signal power (S) and the noise power (N) in the wireless channel. The formula is:

SNR (dB) = 10 * log10 (S/N)

For example, if the signal power is 100 mW and the noise power is 1 mW, the SNR is:

SNR (dB) = 10 * log10 (100/1) = 20 dB

4 How to improve SNR?

To improve Signal-to-Noise Ratio (SNR) and reduce Bit Error Rate (BER) in wireless networks, there are several strategies to consider. Increasing transmit power can boost the signal strength and overcome noise and attenuation, but it can also increase interference and power consumption. Reducing the distance between the transmitter and receiver can reduce path loss and multipath effects, but it can limit coverage and mobility. Choosing a better location can avoid or minimize obstacles that block or degrade the signal, but it may not be feasible or convenient for some applications. Changing the frequency can reduce interference from other devices using the same or adjacent frequencies, but it may affect bandwidth, propagation, and compatibility. Directional antennas can focus the signal in a specific direction and reduce noise from other directions, but it can reduce diversity and flexibility. Using modulation and coding techniques can adjust the number of bits per symbol, error correction schemes, and data rate according to channel conditions, but it increases complexity and latency.

5 Why is SNR important?

Signal-to-noise ratio (SNR) is essential for the performance and reliability of wireless networks. A high SNR allows for a higher data rate and a lower bit error rate (BER), resulting in increased throughput. Additionally, a low SNR causes a higher BER and more retransmissions, leading to greater latency. Moreover, SNR is important for providing quality of service to different applications and users with varying requirements for bandwidth, delay, jitter, and reliability. Consequently, a high SNR enables a better quality of service for the network.