# Tag Info

Accepted

### Flat fading criterion of OFDM subcarrier spacing

Your mathematical derivation is correct, your $H[k]$ is the single-tap equalizer (i.e. one tap for each subcarrier, and the subcarriers do not mix with each other. That's the orthogonal in OFDM). ...
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• 2,222
Accepted

### What's the effect of spread spectrum on frequency- selective channel

In brief, we consider the channel as frequency-selective channel if the frequency of the signal is larger than then frequency of channel No offense, but that ought to win the prize for the least-...
• 2,463
Accepted

### What is the meaning of the channel gain is normalized

Normalizing $h$ means defining it so that the expected value of $|h|$ is equal to 1. The implication is that multi-path is (on average) neither taking energy from $x$ nor adding energy to it. In an ...
• 15.3k

### What are TDL and CDL channel models in principle, and which variation can be used for indoor and outdoor environment, respectively?

I want to share my understanding here for my future self as well as for any other user who happens to have the same question. TDL Model is preferred usually for simplified evaluations (e.g. non-MIMO ...
• 151

### frequency selective channel $\ne$ multi-tap channel?

But the converse is not necessarily true, is it? Ah, it usually is. Here's two aspects we need to address: Is every multi-tap channel frequency selective? We need to differentiate between the ...
• 31.3k

### Flat fading criterion of OFDM subcarrier spacing

There's a lot of very valid aspects that you touch, but from what I've learned (and experienced having fun with OFDM SDR transceivers), the main reasoning to do OFDM is having a narrow-channel ...
• 31.3k

### Channel modelling for wireless body area network

IEEE 802.15.4a defines multiple bands from 2.4 to 10 GHz for operation. You should focus on one. Not sure you're actually looking for diffraction and not more for backscatter from surrounding objects ...
• 31.3k
Accepted

### Brief introduction to wireless communication and communication terminologies

Well, these are very fundamental questions, and I think they are written in any good book. But maybe it's hard to extract the exact information from them, which you ask for. So, let me briefly answer: ...
• 6,238
Accepted

### MIMO System Model in Matlab

In a wireless system, most of the noise is added by the receiver itself. The received signal is very weak (-100 dB or less is typical), and its power is comparable to the thermal noise of the receiver'...
• 15.3k
Accepted

### why did convolution coding achieve BER less than Reed-Solomon?

Reed-Solomon codes are good for correcting bursts of errors (such as those that often occur in computer memory systems such as RAM, or on less volatile media such as CDs and DVDs) or at the output of ...
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### Correct way to simulate Rayleigh fading for indoor environments

Your question is quite unclear, but it seems like you're trying to simulate the continuous-time radio channel. In this model, you do not multiply by complex coefficients; rather, you add delayed and ...
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### Cyclic prefix length in baseband OFDM with ZF equalizer

The channel which you have created is having 4-Taps and all taps are one after the other, meaning roughly there are 4 multi-paths and they are very close to each other. How close depends on what is ...
• 2,611

### what does mean quasi-static channel

Quasi-static channels are a "block-wise" time (in)variant. For example, your channel has no variations over time (not in the delay domain) for some time period(e.g., 1 ms), but the channel ...

### Intersymbol interference due to limited channel bandwidth

Here is a graphic I have that demonstrates ISI due to multipath propogation: Notice the eye diagram in the upper right hand corner showing what we should receive if there was no ISI, or other noise ...
• 52.4k
Accepted

### Is the Channel shortening similar to Time domain Equalizer (TEQ)

Most likely people use different words to describe the same concept. This happens quite often. The TEQ is the more general term and also used to equalize other methods that OFDM, while CS is related ...
• 1,056
Accepted

### How can I generate time-variant Rayleigh channel in MATLAB

Yes, you can have time variant channel in MATLAB either by using comm.RayleighChannel() , you can read about it in help of matlab. or the other way you use the ...
• 1,056
For BPSK it's $$P_e = \frac{1}{2}\left[1 - \sqrt{\frac{\gamma}{\gamma+1}}\right]$$ where $\gamma$ is the average SNR. For 16-QAM, I am not sure if there is a closed-form solution. Check this book. ...