Final answer:
M-ary modulation involves schemes where each symbol represents multiple levels or values, saving bandwidth but reducing immunity to noise compared to binary modulation. More data is transmitted per frequency range with m-ary, but the reduced distance between signal levels makes it more susceptible to noise interference.
Step-by-step explanation:
In the context of communication systems, m-ary modulation refers to modulation schemes where each symbol represents ‘m’ levels or values. For instance, whereas binary modulation (such as BPSK) has two possible states (0 or 1), quaternary modulation (QPSK) has four possible states.
One benefit of m-ary modulation is that it can save bandwidth. In essence, more bits per symbol can be transmitted, allowing more data to be transmitted in each frequency range. This is particularly useful in situations where bandwidth is limited. However, a key drawback of m-ary modulation is its reduced immunity to noise compared to binary modulation. As the number of levels per symbol increases, the distance between each level reduces, making it harder to distinguish between them in the presence of noise or interference.
For example, in an environment with significant noise, a binary signal might still be distinguishable since there are only two levels to differentiate. But for an 8-ary signal, which carries three bits per symbol, each level is closer together. Noise can more easily cause the receiver to confuse one level for another, resulting in errors.