frequency allocation for telecommunication companies
According to Wikipedia, 4G networks (IMT-Advanced)


  Have peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.75 bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink should be possible over less than 67 MHz bandwidth).


The possibility of transferring more than 1 bps/Hz is a direct consequence of the Shannon-Hartley theorem

\$C = B \log_2\left(1+\mathrm{SNR}\right)\$

where C is capacity and B is bandwidth.

Achieving 15 bps/Hz thus requires an SNR of at least 215-1 or about 33,000.