In-building mobile coverage for a two-level retail store

Large-format retail buildings are hostile to mobile signal. Steel framing, low-E glazing, insulated panel and a deep floor plate combine to cut a usable outdoor signal down to nothing thirty metres inside the door. For a store that runs EFTPOS on mobile backup, click-and-collect on handhelds and a two-level floor of staff carrying phones, that is an operational problem rather than a convenience one.

Spark engaged us to design and install a Cel-Fi QUATRA system covering both levels of the Pukekohe store. QUATRA is an active DAS hybrid: it takes a donor signal off air, distributes it over category cable as RF over Ethernet, and powers the remote units over the same cable. That keeps the head end simple, one power outlet at the Network Unit, and puts the coaxial runs only in the last leg between each Coverage Unit and its antennas.

The design placed a single Network Unit in the Level 1 office, fed from a roof-mounted donor antenna through a splitter. Three Coverage Units distribute from it: CU1 on Level 1, CU2 and CU3 on the ground floor, each driving a splitter and a group of omni antennas. Ten antennas in total cover the retail floor, reserves, staff facilities and back-of-house on both levels.

The system was configured for the 700 and 1800 MHz bands in service at the site, and specified so that 850 and 2100 MHz 5G NR can be brought up later without changing the cabling or the antenna layout. Commissioning and ongoing monitoring run through the Cel-Fi WAVE cloud platform, so signal levels and alarms are visible remotely rather than needing a site visit.

All of it went in around a trading store. Antenna positions sat in live retail ceilings, cable routes crossed sales floor and reserves, and no part of the work closed a department during trading hours.

Scope delivered

• High-level design across both levels, with antenna positions set against the store layout
• Roof-mounted donor antenna and splitter feeding the Network Unit
• One QUATRA Network Unit installed in the Level 1 office
• Three Coverage Units, one on Level 1 and two on the ground floor
• Category cable from the Network Unit to each Coverage Unit, carrying RF over Ethernet and PoE
• LMR400 coaxial from each Coverage Unit through a splitter to its antenna group
• Ten omni antennas across retail floor, reserves, staff facilities and back-of-house
• Band configuration for 700 and 1800 MHz, with 850 and 2100 MHz NR headroom
• Commissioning, walk testing and registration on the Cel-Fi WAVE platform
• As-built antenna schedule and system diagram at handover

Project detail

Client	Spark New Zealand
Site	Large-format retail store, Pukekohe
Sector	Retail, in-building cellular
System	Cel-Fi QUATRA active DAS hybrid
Head end	1 Network Unit, off-air donor
Remote units	3 Coverage Units, 10 omni antennas
Distribution	Category cable (RFoE and PoE) to CU, LMR400 to antennas
Bands	700 and 1800 MHz configured, 850 and 2100 MHz NR ready
Coverage area	Approximately 6,000 m² of retail floor over two levels
Monitoring	Cel-Fi WAVE cloud platform

Outcome

• Coverage across both levels including reserves, staff facilities and back-of-house
• Installed during trading, with no department closed to customers
• Remote visibility of signal levels and alarms through the WAVE platform
• Cabling and antenna layout sized so 5G NR can be added without a re-pull