- This topic has 11 replies, 1 voice, and was last updated 10 years, 10 months ago by BHT.
13th March 2010 at 18:06 #61450BHTGuest
I am confused regarding the role of temporary offset in cell reselection.
I have gone through manuals and also threads on this forum.
My conclusion regarding C2 parameters are
CRO: is used to give priority to cell and cell is reported to have better rxlevel then it actually has.
e.g if CRO is 1(2db)means actual rxlev -60 but reported as -58.
Penaly timer: it is the time which is used to keep the MS stay on the cell it is already camped.
if we increase PT it will delay the MS reselection time to other cells.
TO: value 1:10dbm
I am confused with this in formula it is CRO – TO
so if we give Temporary offset will it reduce chances of cell to reselected like if actual rxlev is -60dbm then during PT time cell rxlev will be reported as -70dbm due to Temporary offset.
if i am correct it means temporary offset is used to penalize a cell chances to be reselected.
Please guide me in this matter.
Thanks in advance.14th March 2010 at 08:44 #61451pixGuest
the C2 of a cell is decreased by “TEMPORARY OFFSET” during the time “PENALTY TIME”.
CELL RESELECT OFFSET allows to increase the C2 of a cell indefinitely.
If C2 of cell n is lower than C2 of serving cell, the MS stays in serving cell.
if C2(n) > C2(s) then the MS goes in cell n.
pix14th March 2010 at 17:48 #61452BHTGuest
Thanks for your reply.
So why we prefer to go for PT=31 and CRO to penalize a cell.
I mean to give it less priority to divert traffic to other cells rather then going to use TO to penalize a cell.
Your response is highly appreciated.
Thanks15th March 2010 at 06:27 #61453PrabeenGuest
I have noted at PT=31, C2=C1-CRO where as if PT not= 31, C2=C1+CRO-TO*H(PT-T).
Y we opt for PT=31? also, wat is TO, H, PT and T? theorotical Description is there with me, but i need the practical.15th March 2010 at 10:31 #61454BHTGuest
we Opt for PT=31 if we want to penalize a cell during cell re selection.
It will give negative CRO during cell re selection.15th March 2010 at 12:15 #61455agzGuest
I think,when t is less than the penalty time,then the value of H=1,WHICH GiVeS U A FORMULA,C2=C1+CRO-TO*(PT-t)…
Bt once t exceeds the penalty time ,then H will bcom zero,by which,
C2=C1+CRO….THUS anywz C2>C1,which will lead to camping on to the new cell….15th March 2010 at 12:28 #61456PixGuest
PT=31 is a special case that i didn’t bother explaining. sorry about that.
This special case is :
If PT = 31, then TO is useless and the formula is C2 = C1 – CRO, all the time. This will apply indefinitely.
The usual case is :
if PT < 31, then C2 = C1 + CRO - TO during PT. After PT, C2 = C1 + CRO only. All previous posts by prateen, bht, and agz are correct, so i don't know where is the problem... you just needed a confirmation ? Now let's go a little further : if you want to penalyze a cell, 1/ either you put PT = 31 and increase the CRO. Therefore C2 will decrease. 2/ or, you increase the CRO of the neighbour cells (assuming you never set PT=31 in any cell, i.e. you are in the "usual" case) Best Regards, pix16th March 2010 at 04:59 #61457BHTGuest
I think i was unable to explain the purpose of this thread.
Actually i was trying to make say that why we use PT=31 in cases when we want to divert traffic from one cell.
Why TO is not used more often in these cases?
Is using TO is not an efficient way?
Thanks in advance.16th March 2010 at 09:25 #61458SHELDONGuest
The PT is used to penalise micro or picocells, so that (fast) moving MSs do not reselect those cells.
Consider an MS on a highway being covered by a macro cell. If this MS enters the coverage area of a micro cell, it will try to reselect this cell. After it moves out of the micro cell’s coverage area, it will then have to reselect the macro cell. To prevent this, the PT of the micro cell can be set to eg 15s, to ensure that the MS reselects this cell only if it has stayed in its coverage area for more than 15s. That’s how the PT is used.
SHELDON16th March 2010 at 10:52 #61459BHTGuest
Thanks for the explanation.
BHT16th March 2010 at 11:02 #61460PixGuest
BHT : I confirm, the initial post was unclear 🙂
As Shelon said, the use of PT+TO is a temporary penalty. To be used to distinguish fast moving traffic and slow moving traffic. Or just to avoid ping pong when the MS is in between 2 cells for a while.
The PT=31 + negative CRO is a static penalty, to be used to divert traffic.
(I’d rather give a static bonus to neighbour cells though.)
(sorry to repeat what sheldon has said…)
pix16th March 2010 at 11:49 #61461BHTGuest
My apologies for ambiguous post.
Thanks once again for your help.