SOLiD Unveils DAS In-Building System for Mid-band Spectrum


SOLiD, a company specializing in cellular in-building mobile coverage, introduced two new SOLiD Alliance 5G DAS in-building connectivity products to support the C-band spectrum (3.7-3.98 GHz), with add-on options for the mid-band Auction 110 spectrum (3.45-3.55 GHz). 

The C-band represents the widest bandwidth available to MNOs at 280 MHz, according to the company. SOLiD’s new DAS remote units support the full C-band frequency allocations, enabling MNOs and third-party operators to maximize the capacity of 5G technology. But it came with technical challenges, according to Slavko Djukic, Vice President, Product Line Management and Technology, SOLiD Americas.

“Because of the width of the spectrum band, you have to develop a very linear amplifier that can support that entire band,” he told Inside Towers. “And as you go higher in the power that you’re transmitting, it’s more and more difficult.” The network also uses Time Division Duplex for uplink and downlink data transmission, which is different from the Frequency Division Duplex used for lower frequency bands.

Propagation is another challenge presented by C-band in in-building wireless networks. A 20-watt amplifier is required for the C-band to provide the same coverage provided with 2-watt and 5-watt amplifiers in use for spectrum below 3 GHz. 

With the FCC making the C-band spectrum available in multiple phases through 2023, the modular Alliance DAS platform supports the fully occupied C-band spectrum now, providing future-ready coverage. Additionally, spectrum from Auction 110 (3.45-3.55 GHz) can be added when the MNO demands it.

“If we are upgrading a system there, we’re not just putting in C-band,” Djukic said. “The MNO or neutral host gets 3.45 GHz to 3.55 GHz in the same box. We’re modular so you can add it when you want it.” AT&T will probably be the main driver in this spectrum band, he added.

The SOLiD Alliance C-band DAS remotes use fiber-to-the-edge, as well as SOLiD’s high-power technology in low-power Fiber2Antenna and high-power Fiber2Coax configurations. “This offers design flexibility to efficiently match the coverage footprint of legacy DAS deployments while compensating for C-band’s reduced signal propagation,” he said.

 The Alliance Fiber2Antenna edgeROU 4040 platform includes support for integrated or external antennas, providing 2×2 Multiple-In Multiple-Out (MIMO) antennas, and includes options to add the new Auction 110 spectrum for overlay deployments or four sub-3 GHz bands for greenfield deployments. 

The Alliance Fiber2Coax HROU 4000 remote has external antenna ports, expansion bays to add amplifiers supporting the Auction 110 spectrum, and the capability to provide single input or 2×2 MIMO in each band.

By J. Sharpe Smith, Inside Towers Technology Editor

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