- This topic has 8 replies, 1 voice, and was last updated 14 years, 8 months ago by
.
-
Posts
-
TA Not stable
i mean by that as far as i know 1TA=almost500M and 2TA=more than1000M, so what wonders me is, I’m getting TA value fluctuates like i’m near the site and it gives me 2 or 1 TA value1 TA = 550m
if you’re at 1099m from the site, your TA = 1, if you’re at 1101m from the site, your TA = 2
that’s the theory.. now in reality i assume the multiple reflections can create a longer path than LoS. And fluctuations (fading) of signal can cause changes in the timing advance.
What do you think ?
Conducted a lot of tests about this over long time. The conclusion come to based upon all or combination of the following, TA can be influenced by:
a) different terrains/clutter
b) antenna tilt (service area)
c) reflection
d) internal/external MS antenna
e) etceg: 2400m from mast got TA fluctate TA22, TA24, TA25, TA28. Location in car park area with two-storey buildings surround MS. Antenna height on mast 21M. Mast located in semi rural area
eg: LOS 500m from mast on school buidling MS in open school playing fields TA1 and TA2
Maybe this helpful?
it’s interesting to know about that… but to perform “a lot of” tests about it, it’s a little too much, isn’t it ? 🙂 how come you studied this ?
It was for study into propagation, which included propagation delay in dense, urban, semi-rural and rural areas.
Thank you guys for the answers, pix you said signal fading can cause changing Time advance so how can we stop the signal fading and as paraHO said my city has different clutters there is 30m-40m hight difference in some dense urban area and maybe the antenna hights become different as well.
why do you care so much about timing advance ?
you cannot stop fading.. it’s caused by multiple reflections on obstacles.ok i get that but what do you think about the different heights of the antennas
Zizo if you have not read the follow book, read:
Multipath Phenomena by Blaunstein & Andersen ISBN 1-58053-185-7 Published by Artech House.
Many chapters dedicated to various forms of fading, and Chapter 4 Distribution of Angle of Arrival and Time Delay from an Array of Buildings Placed on Rough Terrain… has some interesting discussion on PDF (probability density function) and LOS & NLOS conditions
