Basic technical info and strategies wanted!

Mobile phone plans, SIM card activation and porting issue
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MarkSnell
Posts: 50
Joined: Sun Sep 21, 2008 10:05 am
Location: Woy Woy NSW

Basic technical info and strategies wanted!

Post by MarkSnell » Sat Jun 02, 2012 1:51 pm

Like others in this forum, over the last three years I have been experiencing diminished mobile/HSPA service at an address which has line of sight to an Optus tower. Where once signal strength was fairly constant and reliable, now it fluctuates wildly and connections are hard to establish or are lost.

I have not been able to find any basic technical information, either in this forum or elsewhere, that explains why this should be the case or what is the best strategy for dealing with it.

The problem exists at an address that I visit regularly in the Upper Yarra Valley in Victoria.

This is becoming increasingly important to me because I am wanting to spend more time there and need to have a reliable internet connection for my work. ADSL is not available and, according to NBN Co, neither is subsidised satellite because wireless broadband is meant to be available.

I have line of sight to the Woori Yallock tower and an external Exetel yagi aerial connected to my modem. While the signal was strong two years ago, now signal levels fluctuate wildly and are mostly low or non-existent. The service has now declined to the point where even phone calls and text messages are problematic. Any signal that does exist appears to come mainly from towers that are much further afield, including Emerald, Macclesfield and Monbulk, and not Woori Yallock.

For example, last week I was unable to get a reliable connection at all. The modem struggled to establish a connection and jumped between GPRS, EDGE and WCDMA. Even a GPRS signal could not be established reliably. An exception to this was on the Sunday, when I was able to get a good strong WCDMA connection with acceptably fast speeds for about four hours.

I got in touch with Exetel support and was given the following explanation:
Please note that optus has confirmed that there are no current issues on the site that you are servicing off.

However according to them they believe the issue that you are having may be due to a network limitation issue at that location and the serving site is no longer providing strong signal at that address most likely due to the increased number of users on that site.

The only way to improve the signal at the your address in that case is by placing new sites in that area but there aren't any immediate plans of of placing new sites in this area.
I would have thought that, if a transmitter was transmitting constantly, it's monitored signal strength would be constant, even if I couldn't establish a connection. I wouldn't have thought it would fluctuate or appear to be non-existent, because of an "increased number of users" interacting with it.

HERE ARE MY QUESTIONS:

How can apparent signal strength decrease when more users are connected to a particular transmitter?
What does the signal strength indicator on a modem or a phone actually show?
How does the phone interact with the tower/s to determine signal strength and to establish a connection (data or otherwise)?

Elsewhere in this forum, the assertion is made that 3G connections use more than one tower at once. Is this really the case?
I have apps in my phones that show me that my phone is connected to one tower at a time. What are these apps actually showing (eg CellTrack for Nokia, CellMapper and NetMonitor for Android)?

Why do people recommend directional yagi aerials (and Exetel supply them) if the technology relies on the use of multiple towers?
Wouldn't non-directional ground-plane whip aerials be more appropriate?

Once a data connection is established and the signal appears to be strong, with a good ping and download/upload speeds, why would it drop out in a line of sight transmission?
Does Optus or Exetel cut data connections in an attempt to provide more opportunities for others to access the data service?

What are my best strategies for maximising the likelihood of connection?
Is there anyone on this forum who lives in the area and knows local conditions and can make a suggestion?

Should I just give up trying to use Exetel at this location (as suggested by the Support response)?


All the best

Mark
Woy Woy NSW

lasithah
Exetel Staff
Posts: 235
Joined: Mon Sep 05, 2011 5:42 pm
Location: Australia

Re: Basic technical info and strategies wanted!

Post by lasithah » Sat Jun 02, 2012 4:39 pm

HERE ARE MY QUESTIONS:

How can apparent signal strength decrease when more users are connected to a particular transmitter?
What does the signal strength indicator on a modem or a phone actually show?
How does the phone interact with the tower/s to determine signal strength and to establish a connection (data or otherwise)?

Elsewhere in this forum, the assertion is made that 3G connections use more than one tower at once. Is this really the case?
I have apps in my phones that show me that my phone is connected to one tower at a time. What are these apps actually showing (eg CellTrack for Nokia, CellMapper and NetMonitor for Android)?

Why do people recommend directional yagi aerials (and Exetel supply them) if the technology relies on the use of multiple towers?
Wouldn't non-directional ground-plane whip aerials be more appropriate?

Once a data connection is established and the signal appears to be strong, with a good ping and download/upload speeds, why would it drop out in a line of sight transmission?
Does Optus or Exetel cut data connections in an attempt to provide more opportunities for others to access the data service?

What are my best strategies for maximising the likelihood of connection?
Is there anyone on this forum who lives in the area and knows local conditions and can make a suggestion?

Should I just give up trying to use Exetel at this location (as suggested by the Support response)?


All the best

Mark
Woy Woy NSW
Hi Mark,

If the tower that you are connected has exceeded the maximum number of users, then you will be connected to the next tower which you get the reception. That might be slightly weaker than the other but it will be the only option.

A mobile device connects to only one tower at once. Most of the mobile apps uses GPS satellite connections to update the location and uses the Internet connection just to load up the map. Also there are some cell info sent with the signals that indicate the location of the tower.

The directional antennas are used on places where you get bad reception and to amplify the signal received from the tower. If all the reception signals are amplified the device will have trouble picking up a signal and will keep handing over from one tower to the other.

Mobile device is picking the signal with the best power. If your device does not have a preferred network mode, then it will pick the one with the best strength and that connection handover from one to another will be experienced as a connection dropout

Hope this helps

If you require more information on your services please reply to the email sent to you. your reference is 5235873

:)

Dazzled
Volunteer Site Admin
Posts: 6003
Joined: Mon Nov 13, 2006 1:16 pm
Location: Sydney

Re: Basic technical info and strategies wanted!

Post by Dazzled » Sat Jun 02, 2012 6:10 pm

The other question you asked was what do these monitor apps actually show. The answer is RSSI, http://en.wikipedia.org/wiki/Rssi.

I've never thought about coding RSSI on a phone, but for pretty well all 3G modems accessed by computers it's simple. If the modem (say a Huawei dongle) is sent the plain text modem AT command string AT+CSQ it will respond with the RSSI value of the present connection, and perhaps the bit error rate. To convert RSSI returned by the modem to graphical bars:
26-31 5 bars
20-25 4 bars
14-19 3 bars (average)
8-13 2 bars
2-7 1 bar
This can be converted into attenuation decibels (dBM) where 0 is a received strength of 1 milliwatt. The formula is dBM = (RSSI * 2) - 113. Negative values fall logarithmically from 0, so weak signals are very weak indeed. This last calculation is useful when comparing antennas (or the improvement from having one). Approx 3 dB difference is half or double the power.

There's an old thread about finding signal strength and tower locations in rural Victoria at viewtopic.php?f=54&t=38231

MarkSnell
Posts: 50
Joined: Sun Sep 21, 2008 10:05 am
Location: Woy Woy NSW

Re: Basic technical info and strategies wanted!

Post by MarkSnell » Sat Jun 02, 2012 7:07 pm

Thank you for the answers.

If I understand this correctly, is it true to say that:

1. The signal strength indicator on a phone or modem is actually measuring the signal strength of the strongest available connection. It will ignore the signal strength of a tower with no available connections, even if the signal itself is stronger.

2. A non-directional antenna would be useful if the tower with the second strongest signal was not in the same direction as the strongest (but unavailable) tower.


MORE QUESTIONS

Are voice and data regarded as the one connection, or are they connected separately? They can/do operate on separate set of frequencies, don't they?
Does this mean a phone will show the strength of the available voice connection while a modem the strength of the available data connection?
And that a data connection may be available where a voice connection is not, as well as vice versa?

Doesn't signal strength (and consequently the level of data loss) determine whether a data connection is made as GPRS, EDGE or WCDMA, rather than each "mode" having its own signal strength?
Are all towers equipped to transmit in all these modes? Are there still 2G-only towers? Do these necessarily handle GPRS data?


Thanks again

Mark

KavindaS
Forum Admin
Posts: 2506
Joined: Wed Dec 23, 2009 3:59 pm
Location: Sydney

Re: Basic technical info and strategies wanted!

Post by KavindaS » Sun Jun 03, 2012 1:28 pm

MarkSnell wrote:Thank you for the answers.

If I understand this correctly, is it true to say that:

1. The signal strength indicator on a phone or modem is actually measuring the signal strength of the strongest available connection. It will ignore the signal strength of a tower with no available connections, even if the signal itself is stronger.

2. A non-directional antenna would be useful if the tower with the second strongest signal was not in the same direction as the strongest (but unavailable) tower.


MORE QUESTIONS

Are voice and data regarded as the one connection, or are they connected separately? They can/do operate on separate set of frequencies, don't they?
Does this mean a phone will show the strength of the available voice connection while a modem the strength of the available data connection?
And that a data connection may be available where a voice connection is not, as well as vice versa?

Doesn't signal strength (and consequently the level of data loss) determine whether a data connection is made as GPRS, EDGE or WCDMA, rather than each "mode" having its own signal strength?
Are all towers equipped to transmit in all these modes? Are there still 2G-only towers? Do these necessarily handle GPRS data?


Thanks again

Mark

Hi Mark,

Please refer viewtopic.php?f=308&t=39456&p=300629#p300629

MarkSnell
Posts: 50
Joined: Sun Sep 21, 2008 10:05 am
Location: Woy Woy NSW

Re: Basic technical info and strategies wanted!

Post by MarkSnell » Mon Jun 11, 2012 8:43 am

I am still interested in answers to my questions (not necessarily from Exetel staff) and a discussion of possible strategies.


All the best

Mark

shoner
Posts: 756
Joined: Mon Apr 20, 2009 2:50 pm

Re: Basic technical info and strategies wanted!

Post by shoner » Mon Jun 11, 2012 6:46 pm

MarkSnell wrote:I am still interested in answers to my questions (not necessarily from Exetel staff) and a discussion of possible strategies.


All the best

Mark

I came across these documents on the web, that might help you..

http://www.privateline.com/mt_cellbasics/
http://en.wikipedia.org/wiki/Universal_ ... ons_System
http://www.insys-icom.com/icom/en/knowl ... prs-basics
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IanS
Posts: 268
Joined: Fri Jun 25, 2004 11:32 pm
Location: Newcastle

Re: Basic technical info and strategies wanted!

Post by IanS » Thu Jun 14, 2012 1:37 am

MarkSnell wrote:
Doesn't signal strength (and consequently the level of data loss) determine whether a data connection is made as GPRS, EDGE or WCDMA, rather than each "mode" having its own signal strength?
From experience, I found that my HSPA modem would intermittently switch from WCDMA to GSM, when there was poor WCDMA signal, but by forcing the modem into 3G only modem, it did maintain a 3G connection (blue LED, instead of green LED) and loaded web pages considerably faster than on GSM. So it appears that if the modem detects a stronger GSM signal, it will favour that over a weaker WCDMA signal

MarkSnell wrote: Are all towers equipped to transmit in all these modes? Are there still 2G-only towers? Do these necessarily handle GPRS data?
No there appears to be a mixture of tower configurations. for instance, around Newcastle West near Market Town shopping centre, I can only get GPRS/Edge on a Galaxy S2 on Optus. Conversely the township of Warrialda (half way between Inverell & Moree) got a new Optus tower a couple of years ago, but it's only 3G and in other locations there appeares to be combination GSM/3G towers.


Ian

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