# Tag Info

Accepted

### Nyquist noiseless channel capacity; how can bit-rate be two times the bandwidth?

I think you're confusing two different (but related) terms. Nyquist says that in a channel of bandwidth $B$ you can transmit up to $2B$ orthogonal pulses per second. So, $R_p \leq 2B$, where $R_p$ is ...
• 15.3k
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### Are capacity and spectral efficiency identical for a dicrete-time digital signal?

The capacity is a property of a channel. A channel can transport no more than a certain amount of information per channel use. When we use a fixed modulation and coding scheme ("discrete-time ...
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### Are capacity and spectral efficiency identical for a dicrete-time digital signal?

I do not know where the 1/2 factor came from in the answer I linked, or why they've used variance of the discrete noise in the SNR, but it appears that capacity and spectral efficiency are the same ...
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### What is the intuition explaining the Shannon-Hartley theorem?

Echoing what already answered: you are approaching this backwards. SNR is a concept that's very fundamental and applicable to way more things that just channel capacity. If you have a signal $y(t)$ ...
• 44.7k
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### What is the intuition explaining the Shannon-Hartley theorem?

Fundamentally, the signal-to-noise-ratio (SNR or $S/N$) is the ratio of signal power to noise power and that power ratio and is usually expressed in $dB$. Shannon and Hartley (likely collaborating at ...
Accepted

### Capacity and channel estimation algorithms: explanation of results

The channel capacity expression you cited is the one with CSI at receiver that means the receiver know perfectly the realization of fading channel, denoted $\mathbf{H}$, but not the realization of ...
• 6,595
Accepted

### Are there any techniques that can achieve higher transmission rate than Shannon capacity?

No, but the capacity formula you mentioned assumes a very specific channel. Other channels may have larger capacities (see "faster than Nyquist signaling", for example in this question). ...
• 15.3k

### Log-normal shadowing and mean power

I guess that the confusion was exactly that $$\mathbb{E}[10^{P_\text{dBm}/10}] \neq 10^{\mathbb{E}[P_\text{dBm}]/10}.$$ Even though the expected dBm under normally distributed shadowing would be $0$,...
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### Difference: Ergodic channel capacity and spectral efficiency

Loosely speaking: Capacity is the supremum of data rate that one can send data with arbitrarily small error probability over a given channel; ergodic capacity is also the supremum of rate with ...
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1 vote
Accepted

### Example of Entropy and Channel Capacity Computation

Since all transitions are equally likely, there is no information in the channel output about the source. Hence, the mutual information, and, consequently, the channel capacity, are zero in this case. ...
• 90k
1 vote
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### Modulation with Maximum Likelihood decoder and capacity

You are correct that OFDM has several drawbacks, such as the required guard band, number of pilots, and its high PAPR. Many alternatives have been developed, with different sets of pros and cons. ...
• 15.3k
1 vote
Accepted

### Assessing relative wireless channel quality using Capacity and Condition Number CDFs

What the CDF of the capacity tells you is how it distributes, which allows you to say something about the quantiles. Ergodic capacity tells you: what capacity will we see on average? Quantiles are ...
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