LTE is said to have speed upto 100 mbps in Downlink, following is the calculation for it:
The speed is the number of bits that can be transmitted in DL in one second with all the resources assigned to a single user. This is the theoretical speed (for political purposes), practical speeds will be less that this as the control, broadcast channels, reference signals have to be accommodated in the same resources.
The speed is calculated starting with the 100 Resource Blocks for 20 MHz. Each Resource Block has 12 Resource Elements. With 1 sub-frame of size 1 ms, there are 1000 sub-frames in 1 sec. Each subframe can carry 7 OFDMA symbols for Normal Cyclic Prefix. If 64 QAM modulation is used, each symbol can communicate 6 bits and with IQ multiplexing the number of bits can be doubled.
Therefore the possible speed is:
100 Resource Blocks (for 20 MHz bandwidth)
X 12 Resource Elements per RB
X 1000 sub-frames per second (1 subframe = 1 ms)
X 7 symbols per sub-frame (Normal Cyclic Prefix)
X 6 (1 symbol in 64 QAM represents 6 bits)
X 2 (IQ multiplexing)
= 100.8 Mbps speed in DL
The speed is the number of bits that can be transmitted in DL in one second with all the resources assigned to a single user. This is the theoretical speed (for political purposes), practical speeds will be less that this as the control, broadcast channels, reference signals have to be accommodated in the same resources.
The speed is calculated starting with the 100 Resource Blocks for 20 MHz. Each Resource Block has 12 Resource Elements. With 1 sub-frame of size 1 ms, there are 1000 sub-frames in 1 sec. Each subframe can carry 7 OFDMA symbols for Normal Cyclic Prefix. If 64 QAM modulation is used, each symbol can communicate 6 bits and with IQ multiplexing the number of bits can be doubled.
Therefore the possible speed is:
100 Resource Blocks (for 20 MHz bandwidth)
X 12 Resource Elements per RB
X 1000 sub-frames per second (1 subframe = 1 ms)
X 7 symbols per sub-frame (Normal Cyclic Prefix)
X 6 (1 symbol in 64 QAM represents 6 bits)
X 2 (IQ multiplexing)
= 100.8 Mbps speed in DL