Question:
A symbol stream contains alternate QPSK and 16-QAM symbols.
If transmitted at 1 mega-symbol per second, the raw data rate is __________ Mbps
(rounded off to one decimal place).
A symbol stream contains alternate QPSK and 16-QAM symbols.
If transmitted at 1 mega-symbol per second, the raw data rate is __________ Mbps
(rounded off to one decimal place).
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When symbol types alternate, the average bits per symbol is the mean of their individual bit capacities.
Updated On: Dec 15, 2025
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Correct Answer: 2.99
Solution and Explanation
Bits per symbol:
- QPSK → 2 bits
- 16-QAM → 4 bits
Symbols alternate: Average bits per symbol: \[ \frac{2 + 4}{2} = 3\ \text{bits/symbol} \] Symbol rate = 1 mega-symbol/s = \[ 1 \times 10^6\ \text{symbols/s} \] Raw data rate: \[ R = 3 \times 10^6\ \text{bits/s} = 3\ \text{Mbps} \] Thus, \[ \boxed{3.0\ \text{Mbps}} \quad (\text{acceptable range: } 2.99\text{–}3.01) \]
- QPSK → 2 bits
- 16-QAM → 4 bits
Symbols alternate: Average bits per symbol: \[ \frac{2 + 4}{2} = 3\ \text{bits/symbol} \] Symbol rate = 1 mega-symbol/s = \[ 1 \times 10^6\ \text{symbols/s} \] Raw data rate: \[ R = 3 \times 10^6\ \text{bits/s} = 3\ \text{Mbps} \] Thus, \[ \boxed{3.0\ \text{Mbps}} \quad (\text{acceptable range: } 2.99\text{–}3.01) \]
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