# Questions tagged [capacity]

Capacity refers to the capability of a channel to transport data, typically measured in bits per channel usage.

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### Why are some Shannon's limit plots exponential rather than logarithmic?

This diagram again. This is clearly not the shape of $\log_2(1+SNR)$ but I very frequently see this instead of this: But this is also a stupid diagram because it doesn't cross at the origin. Also why ...
0answers
28 views

### Current fluctuations with reduced capacity

I simulate a neuron by compartments, where each compartment is represented by an electrical circuit. Myelinated nerves have reduced capacitance - so for example, if $n$ denotes the membrane layers, ...
4answers
279 views

### Are capacity and spectral efficiency identical for a dicrete-time digital signal?

I saw this answer and saw on the wikipedia page that both spectral efficiency and capacity can be measured in bpcu i.e. 'bits/symbol'. I just want to confirm then that they are identical for a ...
1answer
68 views

### Difference: Ergodic channel capacity and spectral efficiency

Can someone explain what is the difference between the capacity and ergodic capacity? Ergodic capacity and spectral efficiency?
1answer
76 views

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

I study a spectral efficiency of a system with a precoding scheme with different channel schemes. Algorithm A for channel estimation gives a smaller estimation error instead of Algorithm B. I have ...
0answers
12 views

### How to send two packets in a point-to-point transmission with NOMA? [duplicate]

If a transmitter T1 has two packets M1 and M2 to send to a receiver R1, can T1 send M1 and M2 at the same time and using the same frequency based on Non-orthogonal multiple access (NOMA)? If T1 sends ...
2answers
53 views

0answers
37 views

### interpretation of simulation results : capacity with precoder

I am studying the concept of computation the capacity. I have early asked about the difference between CSI unknown/ known to transmitter here. In the book about Matlab implementation OFDM system, the ...
0answers
62 views

### Basic results of error correcting codes

Please can someone verify these basic results about error correcting codes. For this example I am using Reed-Solomon because there are functions to calculate the rate $r$ and distance $d$ of the code,...
1answer
49 views

### Example of Entropy and Channel Capacity Computation

Can you help me on verifying if this computation of entropy is correct and on understanding its meaning? I am not sure of the result especially because it is equal to 0: it means that we cannot ...
2answers
111 views

### When channels are in a cascade and are independent is the capacity the sum?

Just wondering if two channels are independent then is the overall capacity, the sum of the individual capacities? For example suppose I have two BEC where the probability of erasure is $\varepsilon$...
1answer
59 views

### Achievable rate for MIMO channel with estimated channel matrix

In a MIMO system, if the receiver has perfect CSI, i.e. knows that channel matrix $\boldsymbol{H}$, then the achievable rate is:  R = \log \left|\boldsymbol{I}+\frac{P}{N_RN_T}\boldsymbol{H}\...
2answers
1k views

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

I'm confused by the Nyquist channel capacity formula. How can channel maximum capacity approach double the bandwidth. $C = 2\times BW \times log_{2}(L)$ bits/sec The way it was explained to me ...
1answer
34 views

### Modulation with Maximum Likelihood decoder and capacity

My question comes from the high spectrum efficiency claim of OFDM. This seems not correct IMHO, at least theoretically. For me, we lose energy in using cyclic prefix, hence OFDM should be a waste of ...
1answer
39 views

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

I have Channel capacity analysis figures for two wireless channels show below: My question: While ergodic capacity in the first subplots are very clear in conveying the channel capacity, How to make ...
0answers
60 views

### Capacity achieving codes for BPSK at low SNR

I don't know a lot about comm system design. I have an AWGN channel and low SNR (-3dB). Bandwidth is constrained to some maximum, B. I would like to know good choices of modulation and coding to ...
1answer
169 views

### Concatenated Deletion & Sticky Channel Capacity

Suppose you are sending information through a deletion channel with a deletion rate of .5 and then the output of this channel is sent through a sticky channel with a repeat rate of .5 also. No error ...