Firebreaker: From my understanding you don't need more bandwidth with LTE advanced in fact you could have much less, of course if I am wrong I would love to be corrected.
Just for a quick comparison:
2G is usually using 200KHz bandwidth per channel, but operators would need minimum 4MHz (20 channels) and it can provide 480Kbps DL speed (EDGE)
3G is usually using 5MHz bandwidth per channel and it can provide 42Mbps DL and 11.5Mbps UL
LTE is usually using 10-20MHz bandwidth per channel and it can provide 300Mbps DL and 75Mbps UL
LTE Advance is usually using 20MHz bandwidth per channel and can provide 1Gbps DL and 500Mbps UL. By using channel aggregation (4 channels max= 100MHz total) it can provide up to 5Gbps DL speed as it was tested by NTT Docomo back in 2007.
(DL= downlink or download, UL= uplink or upload)
The real 4G technology is LTE-Advanced according to 3GPP standards.
I hope it helps. The numbers above are approximate and in ideal conditions. Usually it is lower than these.