# Cyclic shifts applicable for root sequence to generate 1st preamble transmittion (msg1)

Hi All,
zeroCorrelationZoneConfig = 0 means no cyclic shifts applicable for root sequence to generate 1st preamble transmittion (msg1).
Is there any issue in the performance without cyclic shift in msg1 transmission?

Root sequence re-use distance get reduced with cyclic shift 0.

Agree!
Meaning that there will be 64 preamble with only 1 root.
What are the issue to have a 1 root to generate 64 preamble?

There will be only 1 preamble with 1 root sequence.
Hence 64 root sequences required for 64 preambled in 1 cell.
These 64 root sequences cannot be used in nbr cells.

I am saying root (signature) that will be used to generate 64 preamble from root sequence length 838 or 139.
So if cyclic shift zero means 1 root will generate 64 preamble with short or long pach root sequence length.

For example, Long sequence is ZC sequence of 839 sequence length.
So there are 838 root sequences are possible from long sequence.
Each root sequence can generate PRACH prembles = sequence length/ cyclic shift.
Hence if cyclic shift is 0 then there is only 1 preamble from 1 root sequence.

Sequence per root sequence indicates preamble?

Yes, correct.

Does it means I can only have 64 preamble per cell with 13 cyclic shift?

64 preambles per root sequence per cell.

Best way is to divide 839/cyclic shift as per table to get number of signature.

That’s my understanding.
And each signature will have number of preamble.

13 cyclic shift with 1 sequence we are able to generate 64 preamble right?

Yes correct, roundup the number.

With zero cyclic shift what are the issue in the RACH performance?

Does TDD have different pseudo random number 839 or 119?

As I said earlier, if your reuse distance is less, and cell coverage is highly overlapped (Overshooted) then the issue of ghost RACH will apear.
RACH failure, HO failure may increase.

I am getting RACH problem and maxretx failure cause with zero cyclic shift in scg failure.
Is it because of zero cyclic shift?

What is ncs here?

Value of ncs = 0.

Ok then cell range need to be checked as we are using mostly ncs as 8 and 12.