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LTE Subcarriers, Modulation And Frame Structure

LTE Subcarriers, modulation and Frame structure

  • LTE subcarrier is the smallest independent part of an LTE signal.
  • The smallest defined piece of an LTE signal is a single subcarrier is RE (Resource Element).
  • Modulation scheme used in LTE.
  • QPSK
  • 16QAM
  • 64QAM

LTE Frame Structure in FDD

  • Each LTE downlink subcarrier operates in 10 ms long frames.
  • Each frame is made up of 10 subframes, each 1 ms.
  • Each subframe contains 2 slots, each 0.5 ms.
  • Each slot carries seven modulated symbols, which could be QPSK, 16QAM, or 64QAM.

Generic Frame Sequences:

Resource Block

In the frequency domain, 12 subcarriers form one physical resource block (180kHz * 0.5ms). The resource block size is the same for all bandwidths.

2 RB(Resource Block) = 1 Scheduling Block(SB)

1 Scheduling Block(SB)=1 TTI =1 Subframe

Scalable Bandwidth:

  • LTE channel bandwidth can be 1.4, 3, 5, 10, 15, 20 MHz.
  • The wider bandwidth the higher throughput.