How does DS CDMA Work?

Explains the basic signal structure of Direct Sequence Code Division Multiple Access (DS CDMA).

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[blistergeist]

I work tangentially with wireless communications signals in my day job and although I have a good innate understanding of FDMA and TDMA, I was having a hard time grasping the concept of CDMA. This video gave me the clear explanation I was looking for, thank you!

[fifaham]

Now the challenge of synchronizing between the symbol signals and the sequence codes is real challenge. Also what makes it more challenging is having long sequence and knowing when to switch to the next sequence code, syncing is vital or else we lose the received data. It would be greatly appreciated if you could explain how to perform this syncing between code sequence and the correlated original symbol signal data.

[smaaack]

Very clear explanation, thank you! I was struggling with the one given in my textbook

[RisteardB]

Really grateful for your videos, you do a great job!

[alalolol]

Thanks for this wonderful video. Could you further explain how DSSS makes Inter-Symbol Interference negligible in the multi-path scenario?

[georgepalafox]

Hi Sir! Great video and thanks for uploading! Just for my clarification, the psd of the spread signal would be for one chip not for the entire 6 chips, correct?

[gorovskybrankovic]

Hello are we mixing the spread sequence with the bits together? I am wondering how this mixing would result in the frequency domain... I have read from books (what you have also mentioned in the video) that the the resultant spectrum is wider and makes the signal more resistant to interference. But how does that work mathematically I am wondering.

Last but not least, this is a great video 👍

[jamesgordan]

Would this be able to work with chirps? So for instance using Generalized-Chirp like (GCL) Polyphase codes/sequences. In order to closely resemble LoRa..

[jaypatel]

This is wonderful. Thanks for uploading this on my previous request. Had few questions in mind, I was referring "Wireless Communication" book by Rappaport and found out that we need to use the equalizer at Receiver for the time varying channel. How those would affect in this DS-CDMA case ? And i think RAKE receiver would be a way to go as receiver for most of the CDMA system. Is there any simple way for designing a receiver ? Simply let's say we have ADALM PlutoSDR, can we use that as receiver, which i believe is not RAKE receiver. If you can comment on these questions, would be helpful. Thanks for your great work.

[fifaham]

Oh man ... I am now feeling I am 30 years younger LOL

[tuongnguyen]

CDMA seems to be a great idea (theoretically) but what make people abandoned CDMA and move on to OFDMA ?

[deepakdavid]

I never understood CDMA in its core principle, not I got a clear idea thanks

[senantiasa]

3 pluses + 3 minuses = 0 (I understand this)
6 pluses = 1 (What? How? Shouldn't that equal 6 instead?)