What is a BBU in Telecom?

The indoor baseband processing unit is a distributed base station architecture widely used in 3G networks. The RRU and BBU need to be connected through optical fibers. One BBU can support multiple RRUs. The multi-channel solution of BBU+RRU can effectively solve the indoor coverage of large venues.

Main functions of BBU: BBU is the baseband processing unit of the base station. It provides external interfaces and completes the resource management, operation and maintenance, and environmental monitoring functions of the system. BBU includes main control unit FSMF module, baseband extension FBBA and transmission extension FTIF.

Features: Unique multi-channel algorithm realizes spatial isolation, which can reduce interference; coverage capacity can be planned independently; reduces dependence on trunk amplifiers; baseband capacity can be shared, with large expansion space; fiber has no loss, backbone deployment is convenient, and RRU deployment is flexible. But the disadvantage is that it requires adding a photoelectric conversion unit, and the optical fiber is easily damaged and needs to be armored. The difference between the TD-SCDMA indoor distribution system and other 3G systems is that TD-SCDMA is time division duplex (TDD), WCDMA and cdma2000 are frequency division duplex (FDD), and the technical systems of the air interface are also different, so their indoor distribution systems are also different.

Data transmission direction: For the downlink direction: the optical fiber is directly connected from the BBU to the RRU, and the baseband digital signal is transmitted between the BBU and the RRU. In this way, the base station can control a user's signal to be transmitted from the designated RRU channel, which can greatly reduce the impact on other channels in the community. User interference.

For the uplink direction: the user's mobile phone signal is received by the nearest channel, and then transmitted from this channel to the base station through optical fiber, which can also greatly reduce interference between users on different channels. The BBU+RRU solution is very flexible in capacity allocation. Depending on capacity needs, the BBU can be configured to support capacity expansion from 1/6 carrier to 3 carriers per channel without changing the RRU and indoor distribution system.