作者IronHand (蹂躪之爪牙)
看板comm_and_RF
標題[問題] 一個通訊的問題
時間Tue Nov 20 21:33:06 2007
The capacity of a waveform channel can be approximated with a summation of
the capacities of parallel sub-channels which partition the original shaped
K
channel, i.e., C=△WΣlog [1+(sk/nk)]
k=1 2
where sk and nk are the signal and noise power at the k-th sub-channel
respectively. Assume that sk is known, and you want to “jam” the
transmission by arranging a noise distribution with total power of N,
that is, nk satisfies the constraint . What is the “best” noise
distribution that minimizes the channel capacity? (Note:
When derive your results, assume two extreme situations:
the first is to assume that the noise budget is far less than the signal
power. And the second is to assume a much greater noise power than
the signal.)
請指教Orz
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◆ From: 140.113.123.1
1F：→ lovewa:Inverse Water-Filling.... 140.113.144.28 11/20 21:54
2F：推 carbene:當N很小,用log(1+sk/nk)=log(sk/nk) 128.12.150.10 11/21 03:39
3F：→ carbene:N很大時, log(1+sk/nk)=sk/nk 128.12.150.10 11/21 03:41
4F：→ carbene:之後就可以用Lagrange multiplier去解 128.12.150.10 11/21 03:43
5F：→ goodnctu:I don't think it's a good idea to ask 140.113.196.74 11/21 03:49
6F：→ goodnctu:your HW on bbs, at least, you should 140.113.196.74 11/21 03:50
7F：→ goodnctu:post your thoughts first 140.113.196.74 11/21 03:52