PRACH Propagation Delay

[zlobster]

Hi guys
as promissed, attached is a snapshot of an IOS tracing for RAN12. If you look at it you will see a proper message called:" Propagation delay". going to message details window you see ucRachPropagDelay message.to compute your mobile_Distance use this formula:

Mobile_Distance (m)=(ucRachPropagDelay+1.5)*3*78

ucRachPropagDelay= you extract from the message.
3= is the measurement resolution (3 chips)
1.5= is a correction parameter for HW system. in 3GPP (25.435) the formula doesn't include this value.
78 (m)= is the Chip distance.

in this case, the mobile is about (4+1.5)*3*78=1287m

Cheers,

Hi qaqa,

I personally couldn't find the formula about RACH propagation delay. Could you please include the subclause of the 3GPP TS where you found it?

Anyway, I think there's an error in the formula you propose.
I think (4+1.5)*3*78=1287m should be as a sum instead of multiplier, i.e. (4+(-)3+1.5)*78= somewhere from 195 to 663. That's because 3 IS the granularity of the measurements. This means that you cannot distinguish measurements within 3 consecutive chips.

That's just IMHO, though.

6.2.7.5 Propagation Delay [FDD]
Description: One-way radio interface delay as measured during RACH access.
Value range: {0 .. 765 chips}.
Granularity: 3 chips.
Field length: 8 bits.

^taken from 3GPP TS 25.435

'ай със здраве (regards),

[qaqa]

Hi there,

for the formula I provided I did a mistake. the formula should be:

Distance=(PD*3+1.5)*78

@ Zlobster
the section from 3GPP is the same you provided.

For distance calculation formula, The 3 Chips granularity is your sampling for the PD estimation therefore the total number will be PD*Granularity

@ Others
Chip distance is the wavelength, you can calculate it using the formula: [Light_Speed (=3x10^8m/s)]/[Chip_rate(=3.86 Mcps)] =77.72m

thanks

[hesh]

Could anyone tell me how can I extract the information regarding PRACH propagation delay from Huawei RNC?

I used to analyse this KPI to look for overshooting cells in Nokia-Siemens RNC, but I don't know how to extract the same information from Huawei RNC.

Thanks in advance!

Rodrigo Barreto

Hi,

Take IOS data, if You are unable to find IOS data by yourself then ask OMC guys to put IOS trace on any given cell, and take the output of trace and do as mentioned in my doc.

hope this will make your life easy..

[topoffenders]

Hi There;

is the Counter for PD is also available on CHR (cell trace?)

Thanks