Frames and Slots in LTE: Frame structure is basic building block on the air interface which help in the communication between the Mobile Phone and Cell Site. All the channels required for this communication are mapped into this tiny frame structure.

• In time domain one Radio frame (RF) is of 10 ms.
• Each radio frame is divided into 10 subframes (each being 1ms long). Subframes are the fundamental time unit for most LTE processing, like scheduling.
• Each Sub-frame is further divided into 2 – Slots, so total 20 slots in a Radio Frame where each Slot is of 0.5 ms duration.
• Each slot is further divided into OFDM symbols
• Number of OFDM symbols in each slot depends on type of Cyclic Prefix(CP) used.

For Normal CP – 7 OFDM symbols per slot

For Extended CP – 6 OFDM symbols per slot

Fig: Frames and slots structure in LTE:

Resource Block: A resource block is the smallest unit of resources which allocated to a user. The resource block is 1 slot long in time and 180 kHz wide in frequency. In frequency, resource blocks are either 12 x 15 kHz subcarriers or 24 x 7.5 kHz subcarriers wide The number of subcarriers used per resource block for most channels and signals is 12 subcarriers.

Fig: Resource Block in FDD frame: 89600 VSA LTE demodulator currently only supports resource blocks that are 12 subcarriers wide.