The BBU (Building Base Band Unite) indoor baseband processing unit is used to complete the baseband processing functions of the Uu interface (coding, multiplexing, modulation and spread spectrum, etc.), the Iub interface functions of the RNC, and signaling processing, local and remote operation and maintenance functions, as well as the working status monitoring and alarm information reporting functions of the NodeB system.
The function of RRU (Radio Frequency Remote Module) is that the transceiver module completes the conversion of intermediate frequency signals to radio frequency signals; and then through the power amplifier and filter module, the radio frequency signals are emitted through the antenna port. ?
The Radio Remote Unit (RRU) is divided into 4 large modules: IF module, transceiver module, power amplifier and filter module. Digital IF modules are used for modulation and demodulation of optical transmission, digital up and down conversion, A/D conversion, etc.
3G networks use a large number of distributed base station architectures, and optical fiber connections are required between the RRU (Remote Radio Module) and the BBU (Baseband Processing Unit). A BBU can support multiple RRUs. The BBU+RRU multi-channel solution can effectively solve the indoor coverage of large venues.
Optical fiber is used for transmission between the BBU and the RRU, and the RRU is connected to the antenna through coaxial cables and power splitters (couplers). That is, the backbone uses optical fiber and the branches use coaxial cables. In the BBU+RRU TD distribution system, the cell setting is on the BBU control panel. Several RRUs may be connected behind one BBU, but not each RRU is a cell.
Extended information:
The working principle of RRU is: the baseband signal is downlinked through frequency conversion, filtering, radio frequency filtering, linear power amplifier, and then transmitted to the antenna through transmission filtering. Upstream, the received mobile terminal upstream signal is filtered, low-noise amplified, further RF small signal amplified, filtered and down-converted, and then completes analog-to-digital conversion and digital intermediate frequency processing.
There are two connection interfaces between RRU and base station interfaces: CPRI (Common Public Radio Interface) and OBSAI (Open Base Station Architecture Initiative).
Among them, members of the CPRI organization include: Ericsson, Huawei, NEC, Nortel, and Siemens. Members of the OBSAI organization include: Nokia, ZTE, LG, Samsung, and Hyundai.
In terms of signal coverage, RRU can be derived from NodeB through different scrambling methods on the same frequency. It can also be derived from the RNC through different scrambling methods on the same frequency. These two coverage methods are conventional methods. In addition, for 3-sector base stations equipped with redundant channel boards and redundant baseband processing equipment, they can use the baseband pool sharing technology to use the redundant baseband processing equipment. Set as the 4th cell.
Baidu Encyclopedia-bbu
Baidu Encyclopedia-RRU