Passive DAS Solution

The traditional Passive Distributed Antenna System (DAS) comprises two main components: donor sources from various standard networks and a signal distribution system.

Donor sources encompass macro base stations, micro cells, distributed base stations, and various repeaters for relay access. Selection of these sources is based on shared business categories, network demands, and optimal network optimization criteria.

The passive distributed antenna system consists of passive components such as couplers, power dividers, combiners, cables, and passive antennas. The signal is split, balanced, and transmitted through these passive components to each antenna installed in the building, ensuring uniform distribution of indoor signals.

Active DAS solutions

Currently, industry leaders in Active Distributed Antenna System equipment, such as Comba, assert that their systems can accommodate multi-operator multi-band shared networks and 5G ultra-large bandwidth shared networks. They achieve this using 1-2 fiber cores to support up to 4*4 MIMO. 

For instance, Comba's ComFlex solution for traditional Active Distributed Antenna Systems primarily comprises four network elements, illustrated in the figure below.

APOI (Active Point of Interface): Facilitates the coupling of radio frequency signals from the source base station Remote Radio Unit (RRU) of multiple Mobile Network Operators (MNOs). With its built-in active adjustable attenuation module, APOI enables independent control of the attenuation level for each channel. The attenuated signal is then linked to the main access unit (AU) via an RF cable. APOI is typically centrally installed in the main equipment room.

AU (Main Access Unit): Receives the signal from the APOI and converts the radio frequency signal into an optical signal suitable for transmission over optical fibers to the Expansion Unit (EU). The AU is typically centrally located in the main equipment room.

EU (Optical Expansion Unit): Receives the optical signal from the AU, distributes it, and transmits it to the next-level low power remote unit RU-L. It also provides the required power supply for the RU-L. EU is installed in the site equipment room or directly on the wall.

RU-L (Low Power Remote Unit): Receives the optical signal transmitted from the EU, converts it into a radio frequency signal, and broadcasts it through its built-in antennas. Compact, lightweight, and aesthetically pleasing, the RU-L can be easily installed in the indoor target coverage area using ceiling suction or wall mounting.

About Jet Lin:

Jet Lin brings over a decade of expertise to the telecom industry, focusing on in-building enhancement solutions. With a vast experience in optimizing Indoor Building Solutions (IBS), including Passive DAS, Hybrid DAS, and Active DAS, Jet is well-versed in delivering cutting-edge telecommunications solutions. Currently serving as the Technical Pre-sales expert at Comba Network System Ltd., Jet spearheads regional business development across the APAC Region.