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# Why Rxlev in -dBm

Viewing 15 posts - 1 through 15 (of 16 total)
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• #59356 Reply
raza
Guest

can anyone tell me why the rxlev is in negative?

And if suppose rxlev is -60 dbm then do we address it as high rxlev or low rxlev.

#59357 Reply
Rex
Guest

Hi,
Negative value cause it’s less then 1 mW.

#59358 Reply
Baig
Guest

As far as i know about this, it is not due to absolute value of power. actually the rxlevel is calculated with referece to RSSI(Recieve Signal Strength Indicator). RSSI is a vendor based parameter. RxLevel in turn is calculated through manipulation of it. couldn’t find the exact formulation though.please share if anybody knows

#59359 Reply
Pix
Guest

Hi all,

RxLev is a measurement of absolute power.

If RxLev = 0 dBm it means the received level is 1mW
if Rxlev = -3dBm –> 0.5mW
RxLev = -6dBm –> 0.25mW
RxLev = -9dBm –> 0.125 mW
-12dBm –> 0.0625 mW

and so on.

a MS has a measurement range from -47dBm to -110dBm.
-47dBm : high received power
-110dBm : low received power

but the MS can hear stronger than -47dBm, it just can’t report a measurement higher than -47dBm.

RSSI is a coded value representing the RxLev. It is very simple :
-110dBm –> RSSI = 0
-109dBm –> RSSI = 1
-100dBm –> RSSI = 10
-90dBm –> RSSI = 20
-80dBm –> RSSI = 30

Cheers,
Pix

#59360 Reply
Baig
Guest

Thanx for the correction Pix

What measurement would you get if the level is less than -47. I’ve also found level less than -47 on TEMS.

#59361 Reply
pix
Guest

hi,

tems is not standard ms, it can display a wider range of values. however, it can report only within the -47 to -110 dBm (in the meas report, sent to bts/bsc)

if rxlev higher than -47 then the value -47 is used.
if lower than -110dBm then -110dBm is used 🙂

cheers
pix (writing with one hand… sorry for the missing caps)

#59362 Reply
ALI SIDICK
Guest

HI
is someone help me ,how to make process&analyse with tems investigation.and also can help me to find more experience about optimisation network.
BR//
ALI SIDICK

#59363 Reply
Salah
Guest

Sorry engineers but i want to ask what are the best,accepted,poor ranges of rxlev and rxqual?

#59364 Reply
pix
Guest

rxlev good > -75dBm
rxqual good > 4

rxlev bad < -85dBm rxqual bad < 5 cheers pix

#59365 Reply
pix
Guest

oops
rxqual good 0…4
rxqual bad 5…7

sorry 🙁

#59366 Reply
NA
Guest

The formula for W to dBm conversion is X (dBm)=10 log Y (mW)

so when we convert the smaller power as 0.3 mW
that will be written as :-

X dBm = 10 log 0.3
= 10 log 3^(-1)
= – 10 log 3
= – 10*0.477
= – 4.77 dBm

gives 0.3 mW = -4.77 dBm

so, it is clear here why -ve sign pops out to the value when we calculate the Rx level, as Rx level is always smaller, but Tx is always +ve because it is near the transmitter giving much power.

thanx

#59367 Reply
vicky
Guest

i think what we are receiving is the addition and subtraction of Tx power,various gains and losses encountered and when we calculate ( LB) final fig is -ve i.e. rx lev expected.

#59368 Reply
Arif
Guest

can anybody tell me about sudden CSBR increment on any gsm Ericsson’s cell? Parameter tuning didn’t decrease FR traffic. Is it the affect of VOIP call? As it removes automatically!

#59369 Reply
Santos
Guest

hello there would you please help me

I have this

14=-96dbm
15= ??

can you please show me how to calculate this

#59370 Reply
Rex
Guest

Hi Santos,
it’s RSSI coded value against RxLev.
RSSi ranges from 0 to 63 which is equal to range -110 dBm to -47 dBm.
So,
-110 dBm : RSSI=0
-109 dBm : RSSI=1 and so on till
.
.
-47 dBm : RSSI=63.
In your question if -96 dBm is 14 then 15 is -95 dBm.
Regards,
Rex

Viewing 15 posts - 1 through 15 (of 16 total)
Reply To: Reply #59359 in Why Rxlev in -dBm
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