Solutions for metro transit agency

Resolving Pilot Pollution & Coverage Challenges


• Southern California-based metropolitan transit system occupying the 9th and 10th floors of an office building in a downtown core, with a combined square footage of 40,000
• Dropped calls and poor cellular connections were a constant employee complaint
• Lead glass windows and concrete floor construction blocked the carrier signal
• Roof-top antennas were not an option due to a helicopter pad and pilot pollution

• CEL-FI QUATRA Supercell

The QUATRA Supercell greatly enhanced the ability of the Verizon small cell, broadening the footprint in the building on multiple floors.

The Challenge

Pacific Services found that lead glass windows and concrete floors were blocking the cellular signal. Compounding the problem, the 9th and 10th floors where the offices were located were above the height of the macro towers. To resolve the poor cell reception, Pacific Services decided to install CEL-FI QUATRA.

CEL-FI QUATRA is an active DAS hybrid for venues from 10,000 to 500,000 sq. ft. or larger that resolves in-building cellular spotty coverage, poor voice quality, dropped calls, and dead zones plaguing employees and visitors. It can be configured to amplify the cellular signal of one or multiple carriers either from the macro network off-air up to 100 dB gain or from a small cell.

Initially, Pacific Services looked at installing QUATRA off-air, but the building owner would not consider placing an antenna on the roof as there was a roof-top helicopter pad. Also, although the macro signal outside the building was good, pilot pollution was a concern as there were too many pilots cell sites visible.

“One of the challenges on cellular systems when you put up a donor antenna is to pull the signal from a certain macro site. That’s called the pilot. Most donor antennas have a beam width that’s fairly wide, which means they can see multiple sites, or you might have a site close by but there’s another one behind it. The system sometimes will try to jump from one to another,” explains Gary Green, Vice President of Operations at Pacific Services. “In a fairly populated metropolitan area where there are sites all around it, it becomes more difficult to isolate the one you want to pull the signal from. In this case, too many sites were seen which would confuse the system. We decided to isolate it down to a small cell, which we can control, and it’s only one pilot source for the signal.”

As a result, Pacific Data Comms configured CEL-FI QUATRA as a Supercell. A Supercell is created when CEL-FI QUATRA is tethered to one or more small cells for the donor signal (i.e. a large single cell versus multiple small cells). It extends the cellular capacity provided by the small cells uniformly throughout the building right to its perimeter for less than the cost for similar coverage using small cells alone. Also, while interference can occur between small cells installed in proximity, this does not occur with a Supercell.

The Solution

The public transit agency occupies the ninth and tenth floors of a 10-story building with a total square footage of 40,000 on the two floors.

A Verizon small cell was installed in the IT closets in the center of each floor. Each small cell was connected to a CEL-FI QUATRA Network Unit (NU), the head end of a QUATRA system, that was mounted on a wall in the closets.

Using Cat 6 cable, the NUs were connected to four remote internal antennas (called Coverage Units or CUs) on each floor to extend the capacity provided by the small cells uniformly throughout the floors. As QUATRA leverages Power-over-Ethernet (PoE), the CUs were conveniently placed at the optimum locations, evenly spaced per floor on the ceiling tiles facing down, without the need to add power outlets.

The Results

“The QUATRA Supercell greatly enhances the ability of a small cell to extend to a lot of different areas,” says Green. “You can broaden the footprint in a building or multiple floors, or we even have done multiple buildings off one small cell signal source.

This has a major impact on the cost of the solution, according to Green.

“Every time you put in another small cell, each one costs $3,000 to $5,000. Each one has to have its own GPS antenna. Each one has to have a backhaul connection to the ethernet network. It’s not convenient. If it’s in different parts of the building, you may not have a way to get that GPS antenna on there, and you may not have the power where you want it,” Green explains. “As CEL-FI QUATRA uses POE (Power-over-Ethernet), it’s really easy. Just extend the cable out and hang a coverage antenna where you need coverage. CEL-FI QUATRA is one of our leading solutions for medium to small clients, under 500,000 square feet, and it’s been very successful. We have been able to install a QUATRA Supercell for 50 to 60 percent less than the cost of other proposals the clients received.”

  • High-quality solution for the middleprise
  • Supports multi-carrier 3G/4G/LTE voice and data
  • Carrier-approved and unconditionally network safe
  • Can be monitored and managed using CEL-FI WAVE

Contact us today to help with your Cellular Coverage Problems

This CEL-FI installation was undertaken by our partners, in which CEL-FI has a global footprint in almost 100 countries. For a referral to a local expert in your area, please contact us via phone or email.