GSM Mast Installations (Density)

GSM Mast Installations (Density)

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When planning a cellular radio network there are many aspects to consider. The matter of radio technology and their frequencies (carriers) are but two examples. A relevance to be understood from these examples relate to what services may be obtained and delivered through these carriers? GSM for basic voice and text services and W-CDMA providing high data rates for video, gaming and conferencing etc.
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Germane and relevant to obtaining radio services are the radio access technologies needed for that - Masts and Antennas. In radio engineering terms, antennas provide the physical technology to access the services obtained in the radio coverage by use of transmitters and receivers, commonly referred to by the acronym TRXs. The Masts provide the physical location for the siting of the TRXs. An important aspect of Mast installations is knowing the potential customer numbers that will use the services obtained from them. The calculation used for the number of customers and the number of calls that can be handled by one Mast's TRXs is calculated using the Erlang formulae - the number of calls and time length of each call in an hour.
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Generally, though, to understand how Erlang can be used to determine the number of Masts and TRXs for an area let's just say there are 50,000 potential customers for a particular area. Let us also say to retain quality of service three sectors with 2 or 4 TRXs per sector, s222 or s444 respectively, are required. Let's also indicate that it is known that:

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1 TRX = 3 erlang, 2 TRXs = 5 erlang, 3 TRXs = 15 erlang, 4 TRXs = 20 erlang
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The relevant TRXs selected for this Mast installation scenario are 2 TRXs and 4 TRXs.
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Let:
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50,000 x 0.02 erlang, where 0.02 erlang is used per customer = **1000 erlang
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Each sector of an s444 may carry up to 20 erlang x 3 sectors = **60 erlang
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**1000/**60 = 16.7
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Therefore:
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16.7 (17) Mast installations would be needed where a configuration of TRXs s444
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or where
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33.4 (35) Mast installations would be needed where a configuration of TRX s222
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Remember the above is intended only to be illustrative so that it can be used to draw inferences about Masts installations and potential user numbers based upon the density of Masts in an area. An inference, such as, why a Mast further away than Masts sited closer to where a mobile station (MS) may be located routed the text message to the MS?

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There are a large number of issues to be considered but let us take it two important issues to be considered are:

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- Point-to-Area predictions for terrestrial services 30 MHz to 3000 MHz

- Point-to-Point short message service (SMS)

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In relation to point-to-area it could be the height of buildings surrounding the MS may be a cause for a distant Mast routing a point-to-point SMS text message. Alternatively, it may be the routing of the point-to-point SMS text message from a distant Mast occurred because the MS, in the idle mode, was surrounded by Masts that were at call traffic capacity. Alternatively it could be because of a combination of both buildings and call traffic capacity.

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Knowing matters like these are very useful when dealing cell site analysis and a reason why they are incorporated into the Core Skills Knowledge of the TrewMTE training courses:

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GSM Cell Site Analysis Training Course

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Course One: GSM Core Skills Knowledge Course (CSA Part 1)

3-days training

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Course Two: GSM Cell Site Analysis Course (CSA Part 2)

3-days training
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Course Three: GSM Cell Site Analysis Course (CSA Part 3)

3-days training
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3G Cell Site Analysis Training Course

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Course One: 3G Core Skills Knowledge Course (CSA Part 1)

4-days training

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Course Two: 3G Cell Site Analysis Course (CSA Part 2)

3-days training

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Course Three: 3G Cell Site Analysis Course (CSA Part 3)

3-days training

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SIM Card Training

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GSM SIM Card Training Course

3-days training

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USIM/UICC Card Training

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3G USIM/UICC Training Course

3-days training

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GSM/3G Handset Examination Training

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GSM/3G Mobile Telephone Training Course

4-days training

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All courses now have credits towards the MTEB Mobile Telephone Evidence Diploma (MTEdip).

GSM MS List of States for the cell selection process

GSM MS List of States for the cell selection process

The GSM mobile station (MS) enters various states when switched on, but in the idle mode. Three such states are PLMN selection, cell selection and location registration that GSM standards described as a "set of states". The overall state of the mobile is thus a "composite of the states of the three processes". As TS 100 930 makes mention "In some cases, an event which causes a change of state in one process may trigger a change of state in another process, e.g., camping on a cell in a new registration area triggers an LR request." Below are those states relevant for MS cell selection but for a more detailed description of the behaviour of these states read GSM05.08.

C1 Normal Cell Selection ‑ This is the process of initial cell selection, searching all RF channels.
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C2 Stored List Cell Selection ‑ This is the process of initial cell selection where BCCH carrier information (e.g. a BA list) for the selected PLMN is stored in the MS.
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C3 Camped Normally ‑ This is where the MS is camped on a cell of the selected PLMN and may be able to make and receive calls. (Whether or not the MS can make and receive calls depends on the state within the location registration process). The MS monitors received level and the system information and checks whether cell reselection is needed.
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C4 Normal Cell Reselection ‑ This is where the MS has determined that cell reselection is needed and an attempt is being made to reselect a new cell.
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C5 Choose Cell ‑ This is where the MS has returned to idle mode from "connected mode" and is choosing a suitable cell to camp on.
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C6 Any Cell Selection ‑ This is where the MS is unable to camp normally on any cell of the selected PLMN, or cannot obtain service because of certain responses to a location registration (LR) attempt. It is searching for a cell of any PLMN to camp on (so that emergency calls can be made).
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C7 Camped on any Cell ‑ This is where the MS has camped on a cell irrespective of its PLMN identity, so that emergency calls can be made.
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C8 Any Cell Reselection ‑ This is where the MS is attempting to reselect a cell, irrespective of PLMN identity.
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C9 Choose Any Cell ‑ This is where the MS is returning to idle mode, after having entered "connected mode" from the "camped on any cell" state to make an emergency call. It is attempting to find an acceptable cell to camp on.

US Court recognises expectation text message privacy

US Court recognises expectation of text messages privacy

Violation the Fourth Amendment

Right to privacy under Art. I, Sec. 1 of the California Constitution

Interesting case, worth reading, as it relates to a Police Office for the Ontario Police Department and others (one said to be a SWAT Officer) who apparenly used work text messaging services to send personal messages unrelated to work.

U.S. 9th Circuit, June 18, 2008 -

Quon v. Arch Wireless Operating Co., No. 07-55282

Users of text-messaging services have a reasonable expectation of privacy in the contents of copies of messages the service provider stores on its network, the Ninth U.S. Circuit Court of Appeals held on June 18, 2008.

http://www.metnews.com/articles/2008/quon061908.htm