Technical Comments Cell Phone Reception Quality in 
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the USVI 
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Gregory Guannel, Ph.D., UVI CGTC 
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Good morning Senator Blyden, members of the Committee, and those in attendance. 
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My name is Greg Guannel, and I’m the Director of the Caribbean Green Technology Center 
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at the University of the Virgin Islands. We develop and share knowledge on how 
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infrastructure, ecosystems, and institutions interact in the U.S. Virgin Islands, with the goal 
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of supporting more resilient and sustainable development of the islands.  
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Thank you for the opportunity to provide an update on the cell phone reception quality work 
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that we have been working on over the past few years. 
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How do cell phones work? Very simply, your phone connects to the nearest cell tower. That 
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tower connects your call or data to the network, which then routes it to another tower near 
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the person you’re trying to reach. 
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To determine whether a call is good or bad, we need to look at two things. First, signal 
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strength, or how strong the connection is. This depends on distance to towers and 
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obstacles like buildings or hills. Second, there is interference, or how noisy the signal is. 
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This happens when too many users share the network, when towers overlap, or when 
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signals bounce off terrain like water and hills. 
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To quantify the quality of cell reception, we collected data in Fall 2023 and throughout 2024 
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using a mobile app as part of the SpectrumX research program. This is program led by the 
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University of Notre Dame, in collaboration with other universities, including UVI. We 
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measure two key indicators: 
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• RSRP: signal strength: ‘Do I hear the tower?’ 
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• RSRQ: signal quality: ‘Is the signal clear, or is there interference?’ 
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In this study, we focus on RSRQ, because it reflects what people actually experience, that 
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is dropped calls, slow speeds, and instability. Good service requires both a strong signal 
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and a clean signal. 
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Looking across the islands, we see that performance varies significantly by carrier.  
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• Viya generally performs best, though there are weaker areas, particularly in parts of 
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St. Croix. 
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• T-Mobile tends to be in the middle, with generally fair to good quality. 
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• AT&T/Liberty performs the worst overall, with more areas of poor quality. 
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We also see that signal quality varies across time and across space. Some areas are 
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consistently good, while others experience larger variation. Some areas, including parts of 
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St. Thomas and St. John, show significant variation. That means users may experience 
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good service in one location and poor service just a short distance away. This suggests that 
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the issue is not just coverage, but how the network is configured and how signals interact 
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with the environment. In some areas, the signal quality remains relatively stable. But in 
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others, it fluctuates more significantly. That variability is important because even if the 
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average signal looks acceptable, inconsistent performance leads to poor user experience. 
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The box plot summarizes the data collected over many months. Each box represents the 
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typical range of signal quality, and the lines show the extremes. What we see is that all 
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networks show variability, but some networks, particularly Viya, have consistently better 
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quality than others. This confirms the spatial patterns we saw earlier. 
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We also looked at the quality of the signal at one fixed location. We see that even without 
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moving, the signal fluctuates. These oscillations are caused by interference and changing 
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network conditions, such as users joining and leaving the network or signals interacting 
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with the environment. This is why calls may drop or quality may degrade even when you’re 
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standing still. 
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So overall, what we find is that Viya performs best, T-Mobile is intermediate, and 
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AT&T/Liberty performs worst. This suggests that improving service in the Virgin Islands is 
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not just a matter of adding more towers. It also requires better network coordination, 
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managing interference, and understanding how terrain and demand affect performance. I 
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would like to remind you though that these data were taken more than 1 year and a half 
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ago.  
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We are currently doing another campaign, and we expect to have results to present next 
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Spring. Specifically, we are collecting more repeated measurements across locations; 
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analyzing temporal patterns in more detail; and examining the impact of weather and 
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environment. We are also investigating why calls placed on St. Thomas, especially 911, get 
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routed to Puerto-Rico. To do this we are looking at which antennas get pinged when calls a 
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placed at different location on the Northside and in Bordeaux.  
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Thank you for inviting me to present this information. We are happy to come again and give 
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an update in a year or so. 
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