More than 63 TA in Drive Test tools

RAN
1

In TEMS and even new Infovista DT tools you cannot see more than 63 TA even when reaches 219 TA’s in reality.

Why?

Can someone please explain the reason?

2

Normal cell max TA is 63. If extended range cell, TA can be higher.

3

In some GSM protocol layers the granularity of the Timing Advance (TA) is 6 bits (0-63), in other areas it is 8 bits (0-255). So lets say your UE is 30km away from the BTS - at max timing advance (disregarding ext range) - then some protocols will say TA 63, other fields will indicate TA 255.

You need to know the granularity of the specific field you are looking at.

4

Timing Advance for RAR = 0,1,2…,3846
Timing Advance for MAC-CE = 0,1,2…,63
So, need to check what are we actually measuring in TEMS.

1 Like
5

extend cell range is BSS feature; ms no idea about true distnace from antennas thus tems/infovista will never show more than 63 TA’s-8bit
this is because ERC feature uses the true TS+ next consecutive TS bit (actually 156 bits), so it doesn’t matter if the burst arrive late to MS at the end we got (63+156)=219 bits at BSS not at MS