Fiber Optic Repeater is cost-effective for coverage extension without the need of implementing more BTS sites. It can be applied to much larger areas including large public building
POF Fiber Optic Repeater with RS232 Traffic Monitor Port, Model 4106
Amazon.com: USB 3.0 Fiber Optic Extender/Repeater, SuperSpeed 5Gbps, 2 Ports, USB 2.0/1.1 Backward Compatible, FireNEX-5000H+ : Electronics
Fiber Optic Repeaters | Single Mode to Multimode Converters
Amazon.com: 10G SFP+ to SFP+ Fiber to Fiber Media Converter - 10G OEO 3R Transparent Repeater - 2 x Standard Open SFP+ Slots - Universal - Supports 10GB SFP+ Fiber and Copper