Aug 11, 2016

Continued Examination of Technical Witness PRH707 (Alfa)

On 25 July 2016, the Trial Chamber continued to hear testimony from confidential witness PRH707, an employee of the Alfa telecommunications company. For further information on this witness, refer to our March 21 and June 13 blog posts.

Mr. Courcelle-Labrousse, representing the interests of accused Oneissi, questioned the witness on very technical matters related to network coverage and cell station configuration. The Defense’s main concern stemmed from perceived inconsistencies between the lists of cell site azimuth (tilt) values provided by Alfa in 2007 and 2010. The witness repeatedly insisted that it is not unusual for azimuth values to be changed over time. However, these lists were theoretically meant to detail the values that corresponded to February 2005. The witness then surmised, but could not confirm, that the OTP phrased its respective requests for assistance (RFA) in 2007 and 2010 such that the requests did not actually ask for the values for February 2005. This explanation would account for both the inconsistent azimuth values and the cell sites missing from the 2007 list. When questioned by Judge Braidy on whether the missing sites were relevant to the calls allegedly made on the day of Hariri’s assassination, the Defense stated that its aim was to prove that Alfa simply could not confirm important technical details going to the attribution of the accused’s cell phone.

The witness also noted that a difference in azimuth values of 10-15 degrees is not significant. The Defense pointed out greater differences between Security Main and Cell ID logs, but the witness could not put that discrepancy into perspective without being provided the timeframe of the cells’ operation.

The Defense further questioned the witness about the cell sites’ power supply in the event that √Člectricit√© du Liban, the Lebanese national energy company, experiences an outage. The witness testified that the sites are equipped with battery power that allows them to transition to generator usage without service interruption.

The witness then clarified certain terms and processes related to MSC capacity and network congestion. He stated that the network would have been at capacity on the day of Hariri’s assassination, and that this may have prevented redirect retries (cell site handovers) from succeeding. In short, it would have been very difficult to place a call in the Beirut area at that time, especially near the PHOENICIA and PALM BEACH cell stations.

Mr. Courcelle-Labrousse further inquired about processes that may inhibit cell signal. For instance, “fast fading” occurs when a physical obstruction interferes with the signal, whereas “Doppler fading” occurs when the caller is continuously moving, resulting in a  site handover to a  cell that would not normally correspond to the user’s geographical location.
The Defense then asked the witness about the inaccuracies of a predicted coverage map for the Beirut area in February 2005. Counsel noted that one station on the map did not exist in February, but was constructed later in the year. The witness believed that the RFA did not specify the month the OTP desired to capture, so Alfa included all cell stations for that year. This change could affect the predicted coverage area but regardless, the witness estimated that 20-30% of the map could be inaccurate.

On re-examination by the Prosecution the witness was asked to clarify the labeling of the coverage map, but could not provide an answer. He was further asked about the process through which the azimuth value lists were requested, and the witness repeated his belief that the two documents display data for separate years. Lastly, the witness confirmed for the Prosecution that a call data record being registered in spite of congestion is indicative of cell site functionality.

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