Which QAM level has a lower data rate: 64-QAM or 256-QAM?

The correct answer is the first option, which states that 64-QAM has a lower data rate than 256-QAM.

To understand why this is the case, it's important to consider how Quadrature Amplitude Modulation (QAM) works. QAM combines amplitude and phase modulation to transmit data. In QAM levels, the number indicates how many different symbols can be sent over the same bandwidth in a given amount of time.

With 64-QAM, there are 64 distinct symbols that can be transmitted, allowing for a certain amount of data to be sent with each transmission. In comparison, 256-QAM employs 256 distinct symbols, which enables it to send more information per symbol. Since each symbol in 256-QAM carries more bits of information than a symbol in 64-QAM, the data rate achieved with 256-QAM is higher.

Hence, when comparing the two modulation schemes, it becomes clear that 64-QAM will yield a lower data rate than 256-QAM due to the smaller number of symbols available in 64-QAM. This relationship between the asymmetrical number of symbols and the resultant data rate is what makes 64-QAM the correct choice for being the one with