All About Resource Block (RB)

Resource Blocks (RB):
- Basic unit of resource for the LTE air-interface.
- eNodeB scheduler allocates RBs to UE to allow data transfer.
- Defined in both time and frequency domains.

In Time Domain:
- Occupies 0.5 ms slot in time domain.
- Consists of 7 OFDMA symbols when using Normal Cyclic Prefix.
- Consists of 6 OFDMA symbols when using Extended Cyclic Prefix.

In Frequency Domain: 
- Consists of 12 subcarriers.
- Each subcarrier is of 15 KHZ.
- Each RB occupy 12*15 = 180 KHZ in frequency domain.

- The GRID generated by One Sub-Carrier in the Frequency Domain and One Symbol in the Time Domain defines a RESOURCE ELEMENT (RE).
- RB consists of 84 (12*7) REs when using Normal Cyclic Prefix.
- RB consists of 72 (12*6) REs when using Extended Cyclic Prefix.
- A single RE can carry a Single Modulation Symbol (2 bits when using QPSK, 4 bits when using 16QAM, and 6 bits when using 64QAM).