LTE TDD Uplink-downlink configurations


when your network has LTE tdd, the basic configuration is UL-DL Configuration which explained in 3gpp 36.211 need to be configured

Table 4.2-2: Uplink-downlink configurations

Uplink-downlink

configuration

Downlink-to-Uplink

Switch-point periodicity

Subframe number
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

D = Downlink
U = Uplink
S = Special Subframe

if your network has multiple cells TDD you should configure same UL-DL configuration, you can’t configure with different configure because if subframe in cell on downlink, this rules also in subframe uplink

how to see on your network, example  Ericsson (moshell) and Huawei (u2000)

Ericsson: MO: EutranCellTDD attribute: subframeassigment

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Huawei: MO: CELL , Parameter: Subframe Assignment

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not only Subframe Assignment we have to configure also special subframe for configure Downlink part time slot, guard period, and Uplink Part time slot

Table 4.2-1: Configuration of special subframe (lengths of DwPTS/GP/UpPTS)

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Ericsson: MO: EutranCellTDD attribute: specialSubframePattern

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Huawei: MO: CELL , Parameter: Special subframe patterns

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in our network using Uplink-downlink configurations 2 and special subframe 7 with Normal CP. See 3GPP table again, we can calculate this:

UL-DL Config 2 => D:L = 3:1 with 2 Special Subframe

How many DwPTS UpPTS and GP?

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DwPTS = 21952*Ts
UpPTS 4384*Ts

1 Radio Frame = 10ms = 307200Ts
1 Subframe = 1ms = 30720Ts

DwPTS+UpPTS+GP= 1 Subframe = 30720Ts
2192Ts+4384Ts+GP = 30720Ts
GP = 4384Ts

DwPTS ~ 5*GP ~ 5UpPTS, which means 10 Symbol will be allocated for DwPTS + 2 Symbol for GP + 2 Symbol for UpPTS on one special subframe