Now, instead of carrying large and bulky coaxial cables for each transceiver, operators can use lighter and significantly smaller power and fiber cables between the RRU at the top of the tower and the baseband unit (BBU). The fiber link between BBU and RRU, also known as "front-haul", carries RF information using CPRI or OBSAI technology (in 4G-LTE). Essentially, the RF information from the radio is converted to the digital domain and mapped accordingly so it can be deciphered at the BBU and vice versa.
Where CPRI / OBSAI technology offers significant advantages, it also creates headaches for fiber-to-antenna macrocells (FTTA) because any RF maintenance or troubleshooting, such as interference analysis, requires reaching the top of the tower to access the RRU. This represents increased operational expense and safety concerns.
Additionally, cellular site installers must now perform a broader spectrum of testing to ensure all cables, connectors, and other active and passive components are correctly installed and commissioned. This is done to ensure optimal performance of the cellular site, thereby offering the best possible QoE for mobile subscribers and maximum return on investment for the mobile network operator. Some of the key tests that cellular site technicians can perform must be completed before a cellular site is accepted can be summarized as follows.
In 5G, Network Function Virtualization (NFV) separates software from hardware by replacing various network functions, such as firewalls and routers, with virtualized instances running as software. This eliminates the need to invest in numerous costly hardware elements and can also accelerate installation timelines, resulting in faster delivery to customers of revenue-generating services. Network decomposition with functional separation also brings other economic benefits, especially with the introduction of interfaces such as eCPRI.
eCPRI has been designed to become a standardized interface for 5G technology used, for example, in the O-RAN fronthaul interface, such as the Distributed Unit (DU)
Another revolutionary technology that is part of the success of 5G technology is beamforming. Conventional base stations have transmitted signals in various directions without regard to the position of users or target devices. By using arrays based on MIMO (Multiple Input, Multiple Output) technology formed by dozens of small antennas joined in a single formation, signal processing algorithms can be used to determine the most efficient transmission path to each user while being able to send individual packets in multiple directions and then arrange them to arrive at the end user in a previously defined sequence.