Dear sir u are sharing very good information , upcomming research scholars
@mathematicality
3 жыл бұрын
Thank you Prof!
@amahbubul85
3 жыл бұрын
@Wireless Future Thanks for this nice lecture. One question. At the beginning, you considered deterministic channel and then you went for SVD. By deterministic channel, you meant no fading, right? The rank is 1 for such case, no? If that is true, we will never have multiplexing gain, isn't it?
@WirelessFuture
3 жыл бұрын
Yes, deterministic means to fading; that is, no mobility. This doesn't always imply rank 1. You get rank 1 in free-space far-field LOS with single-polarized antennas. Higher rank is obtained when there is dual polarization, there are normally additional paths to the direct LOS path, and the far-field approximation might not be accurate.
@amahbubul85
3 жыл бұрын
@@WirelessFuture thank you very much...So, 'deterministic' means here that there might be path loss and shadowing, and multipaths, but they are fixed due to no mobility, right? How it is different from slow fading case? There also we have all these impairments and the channel g is without any time instant l which means the channel is fixed. I understand that for deterministic channel the channel remains the same for infinite time, while the channel changes after a particular time for slow fading channel. But at least for that time duration, they means the same, no?
@WirelessFuture
3 жыл бұрын
I agree, there is a blurred line between these scenarios. From a capacity computation perspective, the key difference is whether we know the channel at the transmitter in advance (=deterministic channel) or not (slow fading). There is no mobility in the deterministic case so we can easily learn the channel. It might be a fixed deployment. There is slow mobility in the slow fading case, so we need to learn the channel. But we only have time to learn it at the receiver side, maybe because there is no feedback link. This case is not happening so often in practice, since we try to design feedback links or use TDD.
@amahbubul85
3 жыл бұрын
@@WirelessFuture thanks à lot. I am not so clear about what you meant by 'this case' at the end. If we have TDD, we have enough time in slow fading case for Rx to send pilots to the Tx using which the Tx can learn the channel, no? Because no feedback is needed for TDD case and channel changes very slowly for slow fading case, no?
@WirelessFuture
3 жыл бұрын
Yes, that is what I meant. The slow fading case is not so common in practice, since we design systems to avoid it.
@최현규-k8t
3 жыл бұрын
I have two questions here(46:21) you explained that there is no beamforming gain both MISO and SIMO but i am confused because the term |g|^2 q1) Doesn't the term |g|^2 mean beamfroming gain? q2) there are two antenna, so, is diversity gain 2?
@WirelessFuture
3 жыл бұрын
The term ||g||^2 is the sum of the channel gains of all the antennas. It can provide both a beamforming and diversity gain, however, when using space-time block codes, we lose the beamforming gain which can be seen by the fact that we get ||g||^2/2. Dividing by 2 removes the beamforming gain that otherwise would have been 2.
@artie5172
Жыл бұрын
I was wondering if Capacity is complex or real value number...i would be glad if you would help me with this professor
@WirelessFuture
Жыл бұрын
It is positive real-number, measured in bit/s, bit/s/Hz, or bit/symbol (depending on whether the bandwidth is multiplied in front of the logarithm or not).
@최현규-k8t
3 жыл бұрын
thank you very much! and i am wondering... could you explain MIMO-OFDM if you have any chance?
@WirelessFuture
3 жыл бұрын
It will be covered in Lecture 13.
@최현규-k8t
3 жыл бұрын
@@WirelessFuture i really appreciate you!! i will keep listening your great lecture~
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