Welcome to an in-depth exploration of cell sites and networks, crafted for attorneys engaged in civil litigation, particularly those navigating the complexities of commercial vehicle crashes. In this post, we will take a look at the following:
- Brief history of cell phones
- How cell phones work
- Cell Sites
- Sectors
- Leveraging the Data
The aim of this post is to equip legal professionals with a knowledge base to harness the potential of cell phone record analysis and historical cell site data in their investigations.
To truly comprehend the significance of cell sites and networks, let’s delve into a brief historical overview. The concept of a wireless network, characterized by hexagonal cells covered by antennas, was proposed by Douglas Ring of Bell Labs in 1947. A single antenna tower would cover three cells.
In the figure above, each of the three hexagonal cells would represent a sector, and the tower would be in the center. A network of towers would look like the following:
Fast forward to 1973, the inaugural cellular phone call was made by Martin Cooper of Motorola to his rival, Joel Engel, at Bell Labs. This historic call, made in New York using a Motorola Dyna TAC8000X, marked the dawn of cellular communication.
The evolutionary journey of cellular networks is punctuated by key milestones:
- First 1G Network: Japan, 1979
- First US 1G Network: Chicago, 1983
- First 2G Network: Finland, 1991 (coinciding with the advent of text messaging in 1992)
- First 3G Network: Japan, 2001
- First 4G Network: Finland, 2009
- First 5G Network: Qatar, May 2018
- First US 5G Networks: Verizon in Houston, Indianapolis, Los Angeles, and Sacramento in October 2018
Understanding this historical context is foundational to appreciating the world of cell sites and networks.
Cell phones are essentially sophisticated handheld radio transceivers. Unlike traditional radios that use a single frequency for both transmission and reception, cell phones utilize separate frequencies for these functions. The orchestration of this communication happens within the cellular network, comprising several components:
- Mobile Station: The cell phone itself
- Base Transceiver Station (BTS): The cell site or tower
- Base Station Controller (BSC): Coordination and control hub
- Mobile Telephone Switching Office (MTSO) or Mobile Switching Services Centre (MSC): The switch facilitating network connectivity
- Public Switched Telephone Network (PSTN): The legacy copper telephone network
Consider a scenario where an AT&T cell phone calls a Verizon cell phone. The call navigates through the AT&T cell site, the BSC, and the AT&T switch (known as the LAC). Once it’s determined that the receiving phone number is on the Verizon network, the call is routed through the PSTN, then the Verizon switch, the Verizon BSC, and finally, the closest tower to the recipient’s phone.
Cell phones are dependent on the cellular networks to function. Carriers keep records of the cell phones’ communications for billing and maintenance. We can obtain the records the carriers maintain in the normal course of business and leverage them to the advantage of our investigations.
Cell sites can be found in diverse configurations, with the tower being the most prevalent. Some carriers ingeniously integrate cell sites into existing structures, such as buildings, water towers, or electrical towers. Others deploy creative disguises, making cell sites look like trees or flagpoles.
Let’s delve into the specifics of a typical cell site configuration. This tower is a monopole design, and each distinct level represents a different carrier. There are three levels on this tower, and each is for a different carrier.
The ground equipment resides at the base of the tower. There will be ground equipment for each carrier having antennas on the tower. In this case, the tower has antennas for three companies, so there are three ground equipment units at the base of the tower.
Some carriers, like Sprint, deploy equipment in gray metal cabinets without data plates. AT&T, on the other hand, typically employs shelters to house ground equipment, marked with branded data plates. T-Mobile and Verizon have their own identifiable equipment characteristics.
These nuances are crucial for any investigation involving cell site data. Legal professionals should strive to survey each tower critical to their case, paying special attention to those used around the time of the incident.
The concept of sectors plays a pivotal role in understanding how cell sites function. Most cell sites have three sectors on each layer. Each layer of a cell site comprises three sectors, each forming a triangle with antennas facing different directions.
Visualize this as slicing a pizza into three equal parts, with each sector covering 120°.
When viewed from the top, the cell site can be conceptualized as a pizza, with each slice representing a sector. The typical orientation involves sector one facing north or northeast, sector two facing southeast or south, and sector three facing southwest or northwest.
Mapping these sectors involves drawing lines from the cell site at an angle halfway between the sector’s direction and the directions of its neighboring sectors. The Horizontal Beamwidth information in the records, if available, can also be utilized for accurate mapping. This example would represent sector three if sector one was facing north.
This detailed understanding of sectors is invaluable for creating precise visualizations in the mapping phase of an investigation.
In the realm of civil litigation, especially cases involving commercial vehicle crashes, leveraging cell site data can be a game-changer. Attorneys armed with an understanding of cell sites, networks, and cell phone records gain a strategic advantage in presenting compelling evidence. Consider reaching out to an expert to ensure the process if obtaining, analyzing, mapping, and reporting the cell site data goes as smoothly as possible.
When undertaking an investigation, legal professionals should consider the following steps:
- Obtain the Records: Records with cell site information require a proper legal demand, such as a subpoena. The subscriber can give consent to release the cell phone records with call, text, and data logs, but carriers require subpoenas to release cell site location information.
- Analyze the Records: Compare the records to other data known in the case to determine if the records are valuable. The records may show one party in the crash was on the phone or texting at the time of the crash, or the records may show one party was not in the location he or she claimed at the time of the incident.
- Mapping the Data: Visual representations of the location data contained in the cell phone records can tell an impactful story. In some instances, cell phone records can show the paths drivers take over long distances.
- Report the findings: Disclose the findings to the opposition and the court. This disclosure may come in the form of a report, expert testimony in a depo or hearing, or other means. Good cell site data can motivate the opposition to settle quickly.
In conclusion, the multifaceted world of cell sites and networks holds a wealth of information that can significantly impact legal proceedings. Attorneys navigating the digital landscape must recognize the uniqueness of each case and stay abreast of advancements in cellular technology. If you have any questions, please don’t hesitate to reach out to me through the contact form on this page. I would appreciate the opportunity to speak with you about your case and how digital forensics can help.