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Recently i have learnt that unlike GSM that is used in mobile handset for communication, cdma uses broad spectrum frequency ie. the full available spectrum. Basically it is a form of spread spectrum. Do a user uses a unique code to transmit the information and receiver uses the code to pick up thesignal ? Won't it will be difficult for one to pick up the complete signal if send over several discrete frequencies

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  • @Tim_Stewart i thought that wireless networking was in the domain of superuser. I really apologize for a off topic question
    – Sreetama ghosh hazra
    Mar 19, 2019 at 19:39

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You imagine that broad spectrum frequency is the frequency of the signal, but that is not so. The frequency refers to how frequent one can find the data of one communication in the data signal stream.

I quote from the paper Basic note on Spread Spectrum CDMA signals:

In Code Division Multiple Access (CDMA) systems all users transmit in the same bandwidth simultaneously. Communication systems following this concept are "spread spectrum systems". In this transmission technique, the frequency spectrum of a data-signal is spread using a code uncorrelated with that signal. As a result the bandwidth occupancy is much higher then required. The codes used for spreading have low cross-correlation values and are unique to every user. This is the reason that a receiver which has knowledge about the code of the intended transmitter, is capable of selecting the desired signal.

For more detailed info, see Wikipedia Code-division multiple access.

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    @Tim_Stewart: It's about hardware technology, and networking is in our domain. Many posts are in a gray area of relevance. What isn't pertinent is clear, but what is isn't that well-defined.
    – harrymc
    Mar 19, 2019 at 18:50
  • @Tim_Stewart: Didn't know that.
    – harrymc
    Mar 19, 2019 at 18:56
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    @Sreetamaghoshhazra: I don't think this question is advanced enough for engineering.stackexchange.com and it won't fit into android.stackexchange.com, so you might just as well stay here.
    – harrymc
    Mar 19, 2019 at 20:24
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    @Tim_Stewart: This isn't Meta, so long discussions are out. But saying that a technology is out of bounds because it's not used in home computing is: (1) Needs proof, (2) Perhaps will change in the future, (3) May be an invalid argument, since we also have company people asking questions here about software & hardware and large networks.
    – harrymc
    Mar 19, 2019 at 20:42
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    Nothing about an encoding scheme say it has to be used in a particular licenced frequency band or communication medium. Furthermore, this question is about the fundamentals of CDMA and pertains to no specific implementation, not even strictly for cellular systems. The user wants to clarify that they understand something correctly; they aren't trying to start a pirate cell tower. I think it is completely fair to ask this question and you are being rude and unwelcoming to a new user.
    – Andy
    Mar 19, 2019 at 22:07

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