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Signal Strength and Distance

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(@trewmte)
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The intention of my discussion is to ask, do you all consider it is enough what has occurred in that case? For instance, had the witness's role been as an anesthetist assisting a brain surgeon in theatre (thus working in close proximity , similar as one may do in a company), do you think the anesthetist should generally be asked about surgically gaining access to a brain tumour?

Well, even with all of your caveats in mind, I do not think it is fair to be critical of Jeff in this case.

Challenger the witness's name is the one referred to in the article I read. However, there is no personal attack on the witness, himself, for he could be witness-X for all intent and purposes for this discussion. So I am not being critically unfair to this witness.

Plus I detect a little subconscious lack of respect for the ‘back office staff’ such as Jeff; else you would not have even made the distinction. Just a guess but had Jeff been an engineer, like you, perhaps the tone you take would be different.

I did not have in mind or the intention, when I wrote the piece, what you have stated above. Data is dispassionate, so should the expert be.

I am highlighting in the article where a person in a non-rf engineer role has been asked about a technical matter 'generally' based upon information his company told to him. Thus could there be room for error in that generality? I highlighting also had an rf engineer been asked the same question and to give a 'general' purpose response would other effects or requirements be included in the response?


   
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sgrills
(@sgrills)
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I think Trewmte raises a valid wider point regarding CSA and how it is conducted in North America.

What we are seeing here is CSA without network readings. Whilst this may be fine for some cases it can be inaccurate and therefore the limitations must be highlighted. It is only good for a rough 1st approximation and in the light of this what forensic weight does it really have then?

If I were to summarise I would highlight that network operators have the ability to make certain Masts more or less attractive to connect to and therefore the closest Mast or even the Mast with the strongest receive signal may not be chosen to provide service.


   
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(@cowboy)
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sgrills,

How is it possible for a mast to be "more attractive"? It has always been my understanding that the strongest mast will prevail over the closest mast but I was unaware that it could be a selective choice made by the service provider. Is there a reference or publication I could review on this subject?

Thanks,


   
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Passmark
(@passmark)
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Another big factor is antenna type and orientation.

Towers are often be divided into sectors. Or have their antenna focused into a narrow cone shape (for example to point along a busy expressway). So you can be fairly close to a tower but still not get a strong signal from it.

There are also overlapping cells (micro cells and umbrella cells). With the micro cells transmitting at low power compared to the umbrella cells.

There is also dynamic power control where the base station changes the power level during a call, so signal strength can in fact appear somewhat constant (for a while) as you move away from the tower.


   
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sgrills
(@sgrills)
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sgrills,

How is it possible for a mast to be "more attractive"? It has always been my understanding that the strongest mast will prevail over the closest mast but I was unaware that it could be a selective choice made by the service provider. Is there a reference or publication I could review on this subject?

Thanks,

Hi Cowboy,
In GSM, there are algorithms C1 & C2 which are used to derive the choice of which Mast a phone will connect to. Signal strength is a component part of these and therefore a strong signal has a big baring on which Mast may be used - but the network operators can effectively manipulate these.

Therefore a Mast may have a strong signal but the values of C1 and C2 may mean another Mast is actually selected.

As Passmark points out, the role of each Mast in the network is important - not all Mast are the same "type".


   
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(@cowboy)
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My thanks to sgrills and Passmark. I am still very interested in learning more about this topic. Are there any publications or references either of you, or trewmte could recommend?

Gracias,


   
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(@trewmte)
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Joined: 19 years ago
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Topic starter  

Apologies for not responding earlier but been quite busy.

Just to add some additional information to that which SGrills, Passmark, hcso1510 and Jhup have made

It has always been my understanding that the strongest mast will prevail over the closest mast……

Cowboy strongest signal is only one aspect of many ( http//trewmte.blogspot.com/2007/02/gsm-radio-test-measurements-non.html ) that occur in the life cycle of the operation of an MS which the MS/Network will be exposed but from which the Network will ultimately make the decision about latching to a cell and whether communication will take place on that cell or not. Some points you may wish to consider are

i) At power On
ii) Cell selection/reselection process
iii) Idle mode (eg camping on a cell)
iv) OACSU (off air call set up)
v) Dedicated mode (eg in call)
vi) Moving MS (Can I invite you please to look at Image 9 at my blog http//trewmte.blogspot.com/2009/08/cell-site-analysis-csa-images-part-2.html and then consider why the network may switch an MS to a particular cell even before a call has commenced?)
vii) Network switching from 2G-to-3G
viii) Roaming (see http//trewmte.blogspot.com/2010/04/utran-geran-3g-inter-plmn-handover.html and also consider Steering of Roaming [SoR http//www.evolved-intelligence.com/steeringtargets.aspx], Anti-SoR http//gsm.org/membership/members-press-releases/2010/4915.htm etc)

For reference I have introduced above a mix of GSM and WCDMA points. With respect and courtesy to Sprint Nextel I believe they operate CDMA/iDEN networks so it doesn't automatically follow that the above relates to the operation of their networks.


   
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