Search This Blog

Thursday, 19 January 2012

LTE Radio Frames


LTE Radio Frame:                                          Reference: 3G
  • Air Interface For 3G LTE.
  • Manage the different types of information that needs to be carried between the eNodeB and the User Equipment.
  • The frame structures for LTE differ between the Time Division Duplex, TDD and the Frequency Division Duplex, FDD
  • Two adjacent slots constitute a sub-frame of length 1 ms
  • There are two types of LTE frame structure:
    • Type 1:   used for the LTE FDD mode systems.
    • Type 2:   used for the LTE TDD systems.

Type 1 LTE Frame Structure
  • The basic type 1 LTE frame has an overall length of 10 ms.
  • This is then divided into a total of 20 individual slots. 
  • LTE Sub-frames then consist of two slots - in other words there are ten LTE sub-frames within a frame.
Type 1 LTE Frame Structure


Type 2 LTE Frame Structure
  • The frame structure for the type 2 frames used on LTE TDD.
  • The 10 ms frame comprises two half frames, each 5 ms long.
  • Type 2 LTE Frame Structure
  • The LTE half-frames are further split into five sub-frames, each 1ms long.


  • The sub-frames may be divided into
    • Standard sub-frames or
    • Special sub-frames.
The special sub-frames consist of three fields;
  • DwPTS - Downlink Pilot Time Slot
  • GP - Guard Period
  • UpPTS - Uplink Pilot Time Stot.
The fields are individually configurable in terms of length, although the total length of all three together must be 1ms.

LTE TDD sub-frame positions:
  • Possible to dynamically change the up and down-link balance.
  • Characteristics to meet the load conditions.
  • A total of seven up / down-link configurations have been set.
  • These use either 5 ms or 10 ms switch periodicity.
  • In the case of the 5ms switch point periodicity, a special sub-frame exists in both half frames.
  • In the case of the 10 ms periodicity, the special sub-frame exists in the first half frame only.
  • Sub-frames 0 and 5 as well as DwPTS are always reserved for the down-link.
  • UpPTS and the sub-frame immediately following the special sub-frame are always reserved for the up-link transmission.

Uplink-downlink configuration
Downlink to uplink switch periodicity
Subframe number
 Slot No
 
0
1
2
3
4
5
6
7
8
9
0
5 ms
D
S
U
U
U
D
S
U
U
U
1
5 ms
D
S
U
U
D
D
S
U
U
D
2
5 ms
D
S
U
D
D
D
S
U
D
D
3
10 ms
D
S
U
U
U
D
D
D
D
D
4
10 ms
D
S
U
U
D
D
D
D
D
D
5
10 ms
D
S
U
D
D
D
D
D
D
D
6
5 ms
D
S
U
U
U
D
S
U
U
D
Where:
    D is a sub-frame for down-link transmission
    S is a "special" sub-frame used for a guard time
    U is a sub-frame for up-link transmission
Uplink / Downlink subframe configurations for LTE TDD

4 comments:

  1. Good one. Thanks

    ReplyDelete
  2. nice one thanks

    ReplyDelete
  3. why LTE frame is of 10ms. what factor decides frame lenght?

    ReplyDelete

  4. Master Framing are the experts in framing in Sydney.
    We specialize in memorabilia framing, custom picture framing, canvas stretching and photo mounting.
    We have grown into one of the most competitive picture framers in New South Wales,
    offering a large range of picture frames and picture framing services.

    corporate framing

    ReplyDelete