trying to put all your more than important inputs together and making deeper calculations with real values, I think I am able to give a more visual case to clarify the original question. More specifically, I will try to demonstrate that 10MHz BW is not enough to achieve the 100Mbps desired. I will base the calculations in the following scenario:

FDD access * BW configuration, setting up the Resource Block number to 50

* MIMO

Normal CP CFI=2 Very goof RF conditions. CQI=15 => 64QAM & 948/1024 coding

Original question: To deliver 100Mbit/s to the end user, how much bandwidth is needed in LTE spectrum? And which spectrum band should be used?

* As for "100Mbps to the end user" I understand real data that the user is consuming (video streaming, voice), so I will focus on the PDSCH Resource Elements to calculate it.

* I will calculate the number of resource elements assigned to PDSCH by frame, since the pattern repeats each frame:

* x 12subcarriers x 7 symbols x 2 slots x 10 subframes= 84000 Resource Elements per Frame

If you deduce the resource blocks per frame assigned to:

PCFICH, PHICH in each subframe PDCCH in each subframe RS1, RS2 in each slot PBCH in second slot in the first subframe P-SCH & S-SCH: in first slot in the 1st and 6th subframes.

(The global idea of the mapping could be seen here: http://wireless.agilent.com/wireless/helpfiles/n7624b/resource_mapping_graph_downlink.htm)

The number of resource elements assigned to PDSCH is around 60000 RE/10 ms.

With an average of: 1. MRE/s for PDSCH

* Applying the CQI value, due to nice RF path to the UE, and the MIMO condition, we have:

CQI=15 => 64QAM => 6 bits per RE CQI=15 => 948/1024 bit coding rate.

So: 

* x 6 bits/RE x (948/1024)= 33.3Mbps

Having 2x2 MIMO configuration: * x 2 = 66.6Mbps

* Conclusion:

* would be the maximum DL real throughput (PDSCH) that the user could get with this configuration.

So either the number of antennas change into 4x4 (most difficult and expensive to implement) giving us 133.2Mbps, or we select higher bandwidth like 20MHz which will increase the number of RE and the tput.

I hope this clarified that higher BW than 10MHz must be used for achieving 100Mbps at the moment since the 4x4 antenna solutions is still not really feasible nowadays.

Notice that very good RF conditions are needed to achieve those values. If the UE is in the edge of the cell, the Tput values will decrease since the modulation scheme will change. Another important fact that Jawad pointed out is that only 1 UE should be in the cell at the time to achieve such results.

I totally agree with Jawad that high peak rates have more marketing purposes than engineering ones since 1 UE in the cell says nothing about performance of the system to me...