LTE PRACH Planning

**Shakeel_15** · 2013-02-12, 05:32 AM

HI,

Does anyone has lte PRACH and PCi plnning document. Please share.

BR

**Finetopix** · 2013-02-12 05:32 AM

**s52d** · 2013-02-12, 02:35 PM

PRACH:
http://lteuniversity.com/get_trained...-planning.aspx

in short: given 15 km cell radius, use step of 10.
So, allocate one out of 83 root sequences to each cell, making sure they repeat as far away as possible.

PCI: until you really sinchronize sites, just allocate different PCI to every cell, minimizing possibility to false detection.
In fact, allocate PCI group to the site (168 different groups), then add 0/1/2 for cells.

With some modification, same SW as BCCH planning in BSS or scrambling code planning in UTRAN can be used.

As numbers are high (83, 168) it is really simple to do it.

BR
s52d

**MINTO** · 2013-02-12, 10:06 PM

be careful when planning PCI...

Always consider PCI MOD 3 , MOD 6 ,MOD 30.

**s52d** · 2013-02-13, 02:20 AM

Originally Posted by MINTO

be careful when planning PCI...

Always consider PCI MOD 3 , MOD 6 ,MOD 30.

PCI mod 30: In my mind, this is valid only if sites are in time sync (COMP etc). With legacy LTE, we keep frequency
accurate, but not time: thus, PCI mod 30 is hardly relevant...

Anyone with practical experience?

BR
s52d

**edinburgh** · 2013-02-13, 08:51 AM

Currently MOD 3 with 2000 sites, still no problem..

PCI (0-513) MOD 3 , step 1
Root sequence (0-830), step 10

**MINTO** · 2013-02-17, 02:45 PM

Originally Posted by s52d

PCI mod 30: In my mind, this is valid only if sites are in time sync (COMP etc). With legacy LTE, we keep frequency
accurate, but not time: thus, PCI mod 30 is hardly relevant...

Anyone with practical experience?

BR
s52d

I think...PCI MOD30 is valid for all cases... PCI MOD 30 is used for DM-RS & SRS.

all the networks around the world are planned for PCI MOD 6 at least so PCI MOD 30 conditions are already satisfied.