Friday, August 23, 2013

Operational Audit Check (OAC) is part of Cell Site Analaysis (CSA)

Cell Tower Fire 

There is a news aticle on about a mast (US cell tower) that caught figure during an install/maintenance work ( The article provides us with a useful reminder when conducting cell site analysis (CSA) to remember to conduct an operational audit check (OAC) and request confirmation that the target mast and the density of support radio coverage masts in the immediate area were all operational at the material time. This should be requested as soon as practicalable to do so.

Invariably, an event (e.g. a serious crime) requires instant action and requires, if relevant, knowing the cell coverage at the scene of crime (SoC) and the coverage in surrounding areas (e.g. identifying potential get away routes). It could impact the investigation if an OAC is not conducted regarding the density of surrounding masts and it later comes to light a mast was out of commission for a period and other masts in trh surrounding area had their coverage increased.

In some cases, it may not be possible at short notice to draught-in coverage from other masts and a radio black spot may occur. This, too, is in important to anticipate and be considered when analysing call records, road networks and the density of masts (thus coverage) upon the landscape. Moreover, if the out of commission mast is at a central location of a road network or town/city, consider also the base stations delivering small cell/micro cell coverage. Many of these base stations have their antennas tilted. There are two types of tilt commonly available: electrical and mechanical. Electrical tilt enables the network to remotely alter the tilt angle of the antennas. Mechanical tilt requires an engineer to visit site and mechanically alter the antenna tilt. Here again, not considering these points could mean an investigation can include arriving at erroneous conclusions that may be uncovered later on.

My experience of performing OAC for particular cases can vary from the experience of others. I am not able to say why information I have found was available was not accessible to other experts/investigators. It seems to me that an illustration of the information that supports the above comments I made should be demonstrated. I have hidden some cell site/mast details from the data served in a particular case, that of site name, address and NGR, as this relevation is not necessary to specifically identity the cell site/mast details in that particular case. However, it is assumed that site name, address and NGR are standard details that form part of the request of the information sought from a particular operator.

Below is further reading material I hope you will find helpful, which I have produced here at the blog in the past, and that the events/actions mentioned in them might provide further support or clarity to you about the issues discussed above or during an investigation.

LTE, Test Trials and Cell Site Analysis

CSA - R&TTE Directive

GSM Mast Installations (Density)

Basic Terrain Plot, GPS & CSA

CSA: From Ockham's (Occam's) Razor to Checking Masts

Cell Site Analysis (CSA) Images

Cell Site Analysis (CSA) Images Part 2

Cell Site Analysis (CSA) Images

Mobile Phones and Fringe Coverage

Evolving Cell Site Analysis (CSA)

Mini Course in Cell Site Identification (Pt3.s2)

Mini Course in Cell Site Identification (Pt3.s1)

Mini Course in Cell Site Identification (Pt2)

Mini Course in Cell Site Identification (Pt1)

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