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I know this is a very specific question but hopefully one of you in the forum is a telco engineer. So can you explain in a very high level how the above quantities are related?
thanks in advance.
btw, i'm not sure if this is the correct category to post this
Registered Member #207
Joined: Sat Feb 18 2006, 05:14PM
Location:
Posts: 45
I may be able to help. But first, could you define CQI? I'm going to guess you mean Channel Quality Indicator. That is, somesort of message indicating qualitative analysis like RSSI and Bit Error Rate. No?
Also, a little bit more background would probably yield you better answers. I mean, telecom is a pretty vast field. And "block error" could encompass anything from simple transmission packet loss (in one of dozens of transmission protocols) to errors in image decompression after transmission. Again, pretty vague.
My gut is telling me this has something to do with broadcast digital television :)
I may be able to help. But first, could you define CQI? I'm going to guess you mean Channel Quality Indicator. That is, somesort of message indicating qualitative analysis like RSSI and Bit Error Rate. No?
Also, a little bit more background would probably yield you better answers. I mean, telecom is a pretty vast field. And "block error" could encompass anything from simple transmission packet loss (in one of dozens of transmission protocols) to errors in image decompression after transmission. Again, pretty vague.
My gut is telling me this has something to do with broadcast digital television :)
thanks for the response deef. This is with regard to HSDPA. I'm doing some simulations as my thesis project in university, for this I'm using the NS2 network simulator with HSDPA extensions.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
In communications theory, noise is always assumed to be "AWGN" - Additive White Gaussian Noise - even if it isn't actually in practice. So, all of the fundamental quantities are related by the statistics of Gaussian noise.
For example, to get bit error rate from SNR, you use the channel bandwidth and SNR to calculate the mean and variance of the noise at the detector, then you can estimate the BER from the tails of the Gaussian distribution having that mean and variance. (The BER is the odds of a noise pulse big enough to overcome the signal and knock the detector into the wrong state.)
Algorithm-specific quantities like block error rate and channel quality indicator follow from the bit error rate, plus the error-correcting and reporting properties of the algorithm itself. (For example, you can calculate the block error rate if you know the BER, the number of bits in a block, and how many single-bit errors it takes to use up the error correction and destroy a block.)
In a previous job I wrote educational software to calculate BER from an eye diagram captured by a digital scope, using the Gaussian assumptions.
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Relationship between block error rate CQI and SNR
