Define RSSI and SNR in wireless terms and explain how they affect link quality.

• A. RSSI is the received signal strength; SNR is the ratio of noise to signal.
• B. RSSI is the received signal strength; SNR is the ratio of signal power to noise; higher values indicate stronger, clearer links and better data rates.
• C. RSSI measures noise floor; SNR measures channel bandwidth.
• D. RSSI measures latency; SNR measures packet loss.

Answer: (B)

Two metrics define how well a wireless link is likely to perform: RSSI and SNR. RSSI measures how strong the signal is when it arrives at the receiver—the louder the signal at the antenna, the higher the RSSI (usually expressed as a dBm value, with less negative numbers meaning stronger signal). SNR is the ratio of the signal power to the noise power, typically expressed in decibels. A higher SNR means the signal stands out more clearly from the background noise.

Why this combination matters: a strong RSSI helps the receiver detect the signal more reliably, especially across distance or through obstacles. But what really governs how fast you can transmit and how often errors occur is the SNR. If the signal is strong but the noise is also strong (low SNR), errors creep in and data rates drop. If the signal is strong and the noise is low (high SNR), decoding is easier, enabling higher data rates and lower error rates. So, higher RSSI and higher SNR generally point to a better link quality, with SNR often being the critical factor for achievable throughput and reliability.

The other statements don’t fit because RSSI is not a measure of the noise floor itself, and SNR is not about bandwidth. RSSI isn’t latency, and SNR isn’t about packet loss.