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In my phone, it says that the downstream bandwidth of LTE is 10Mhz. But if a carrier frequency of 900Mhz has a bandwidth of 20Mhz, i.e., frequency ranges from 900Mhz to 920Mhz, then I have almost half the BW of my base station. It's impossible. Can you approximately tell me how much BW will I get if there are a 1000 users in vicinity of that base station?

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You may have that peak bandwidth available on your particular phone. LTE is very adaptive. When you want a burst of data, you get a burst of data. When you don't, others are using those spectrum resources.

This is an excellent overview of how the system works.

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  • \$\begingroup\$ Does that mean 10Mhz BW is divided into all users \$\endgroup\$ – Shashank May 12 at 14:51
  • \$\begingroup\$ No, it means that a bandwidth that can be anything from 1.4 MHz to 20 MHz serves all the users in the cell, giving any one with a suitable terminal up to about 300 Mbit/s, when using 4x4 spatial multiplexing in 20 MHz. It's your phone that's limiting you to 10 Mbit/s. LTE is not circuit switched, it's packet switched, using the same sort of protocol as the internet. Check out en.wikipedia.org/wiki/LTE_(telecommunication) \$\endgroup\$ – Neil_UK May 12 at 16:02
  • \$\begingroup\$ What if all users are equally demanding high BW then in that case each one gets 20khz if there are a total 1000 users with a basestation BW of 20Mhz is this correct? \$\endgroup\$ – Shashank May 12 at 16:27
  • \$\begingroup\$ Not quite. The basic basestation resource is a 500uS slot of twelve 15 kHz wide occupying 180 kHz. Each user gets allocated as many of these as are required to service their data rate. See the excellent overview I've linked in my answer. With 64QAM, and full 4x4 spatial multiplexing in suitable RF conditions (equivalent to using the bandwidth up to four times over), you can get 300 Mbit/s in that 20 MHz bandwidth. Yes, I didn't believe spatial multiplexing either when I first heard about it. \$\endgroup\$ – Neil_UK May 12 at 16:42
  • \$\begingroup\$ But a 20Mhz channel of 64qam gives a bit rate of 20M x 6=120mbps (as 64qam has 6 symbols per bit) as u said 300 mbps is max bit rate so spatial multiplexing gives bit rate about 2.5 times (ie 300/120) the normal bit rate. But u said it’s 4 times . which one is true ? thanks for ur answer \$\endgroup\$ – Shashank May 15 at 19:33
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Your signal (on the downlink from base station to your phone) may occupy 10 MHz, but that doesn't mean you have exclusive use of that 10 MHz. It is likely being shared with other phones that are also connecting to the system through the same base station. This sharing is sometimes known as multiplexing or multiple access (although multiple access, strictly speaking, should apply only in the uplink direction from phone to base station). The radio interface technology that LTE uses to accomplish this is OFDMA - Orthogonal Frequency Division Multiple Access.

You can think of it as there being a time-frequency grid of discrete resources, that are allocated to different phones dynamically.

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