LTE Frame Structure

LTE FDD FRAME:

FDD Frame used for FDD technology.FDD is frequency division duplex which have different frequencies for both DL and UL at a same time. Below mentioned FDD frame.                                                                                                                                          see 5G frame structure

Levels in FDD Frame             see frame structure interview que & ans

1^st Level

1 Radio Frame=10 ms

Short CP=140 ofdm symbols and Long CP=120 ofdm symbols

2^nd Level

1 Sub frame=1ms

Short CP=14 ofdm symbols and Long CP=12 ofdm symbols

3^rd Level

1 Time slot=0.5ms

Short CP=7 ofdm symbols and Long CP=6 ofdm symbols.

TIME UNIT IN LTE

·         Ts(Standard Time in LTE)= 1/(15000*2048)sec-->32ns

v  It’s a smallest unit of time in LTE operation

·         T_slot=15360Ts=15360(1/(15000*2048))-->0.5ms

·         A sub frame is equal to 30720Ts=1ms

·         A Radio frame is equal to 307200Ts=10ms

·         A radio frame = 20 T_slot

LTE TIME SLOT DIVISION

Time slot having two categories

·         Short CP Time slot

·         Long CP Time slot:

LTE TDD FRAME:

In TDD (Time division duplex) technique we are using, same frequency or frame for both DL and UL but at a different time.

·         It consists in a category of Frame 2

·         Radio frame size= 10 ms

·         Sub-frame size=  1 ms

·         Time slot size= 0.5 ms

·         Each Radio frame consists two half frames.

TDD have a special sub frame (1,6) when downlink-to-uplink switch-point-periodicity is 5ms.

TDD have a special sub frame (1) when downlink-to-uplink switch-point-periodicity is 10ms.

Special Sub-frame carries following info:

DwPTS: Downlink pilot time slot

UpPTS: Uplink pilot time slot

Guard time: It is time using for switching from downlink to uplink so that interference can be eliminated.

LTE TDD UPLINK AND DOWNLINK CONFIGURATION:

*Note: operators choose any 1 configuration out of (7 configurations) as per their users requirements.        see LTE Protocol interview que & ans