What is the specific difference between BBU and RRU?

BBU and RRU don't know the difference, because they are not homogeneous concepts, but what is the specific connection between them. I hope the content will help you a little.

Radio remote unit-wireless remote unit

The technical feature is that the base station is divided into two parts: the near-end machine (radio server) and the far-end machine (RRU). The two parts are connected by optical fiber, and the interface is based on the open CPRI interface, which can stably connect the equipment of mainstream manufacturers. RS can be installed in a suitable location in the computer room, and RRU is installed at the antenna end. This separates a part of the previous base station module. By separating RS from RRU, the tedious maintenance work can be simplified to the RS end, and one RS can connect multiple RRUs, which not only saves space, but also reduces the setup cost and improves the networking efficiency. At the same time, the interface between the two uses optical fiber, so the loss is small.

Building baseband unit-indoor baseband processing unit

Distributed base station architecture is widely used in 3G networks, and optical fiber connection is needed between RRU (Radio Frequency Remote Module) and BBU (Baseband Processing Unit). A BBU can support multiple rrus. The multi-channel scheme of BBU+RRU can solve the indoor coverage of large venues well.

Usually there are floors between floors of large buildings, rooms have walls, and indoor and indoor users have space division. The multi-channel scheme of BBU+RRU takes advantage of this feature. For a large stadium with an area of more than 6,543,800 square meters, the stands can be divided into several communities, and each community is provided with several channels, and each channel corresponds to a flat antenna.

Usually, the indoor distribution system adopts the electrical distribution mode of cables, while the BBU+RRU scheme adopts the distribution mode of optical fiber transmission. Baseband BBU (Building Baseband Dunite Indoor Baseband Processing Unit) is centrally placed in the machine room, and RRU(RRU Remote Radio Frequency Module (Rera()teradioune) can be installed on the ground. Optical fiber transmission is used between BBU and RRU, and RRU is connected to antenna through coaxial cable and power divider (coupler), that is, optical fiber is used in trunk line and coaxial cable is used in branch line.

For the downlink direction: the optical fiber is directly connected from BBU to RRU, and the baseband digital signal is transmitted between BBU and RRU, so that the base station can control a user's signal to be transmitted from the designated RRU channel, which can greatly reduce the interference to users on other channels in the cell.

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

Theory and practice prove that the scheme has the following characteristics: the unique multi-channel algorithm realizes spatial isolation and can reduce interference; Coverage and capacity can be planned independently; Reduce dependence on trunk amplifiers; Baseband capacity * * * can be enjoyed, and the capacity expansion is large; Optical fiber is lossless, backbone network is easy to deploy and RRU is flexible to deploy. However, the disadvantage is that the photoelectric conversion unit needs to be added, and the optical fiber is easy to be damaged and needs to be armored. The difference between TD-SCDMA indoor distribution system and other 3G is that TD-SCDMA is time division duplex (TDD), WCDMA and cdma2000 are frequency division duplex (FDD), and the technical system of air interface is also different, so its indoor distribution system is also different.

Indoor distribution systems mainly come from different sources, including Hong Jizhan, micro-base stations, remote base stations and repeaters. (1) Hong Fengwo information source: It is mainly used in high-grade office buildings, shopping malls, star-rated hotels, Olympic venues and other important buildings with large telephone traffic and large coverage area. (2) Micro-cellular information source: mainly used for medium-flow and small and medium-sized buildings. (3) Remote source: a large-capacity base station, which is mainly used in important buildings with large telephone traffic, such as office buildings, shopping malls and hotels, and is especially suitable for building coverage. (4) Repeater information source: mainly used to cover scattered residential areas, elevators and basements in blind areas. The difference between 3G network and 2G network is that 3G network works in 2000MHz band, the radio wave propagation loss is greater than 2G band, and the signal penetration ability is weaker than 2G band. Moreover, 3G high-speed data services need stronger signal strength and signal quality, and indoor coverage can not be satisfied only by outdoor Hong Jizhan. Low-rise buildings and underground garages often have local blind spots, so it is usually necessary to build active and passive indoor distribution systems.

At present, TD-SCDMA industry has matured and started large-scale commercialization. TD-SCDMA adopts smart antenna technology, which inevitably brings the problem of too many feeders. Node B based on BBU (baseband unit) +RRU (remote radio unit) structure, which separates baseband and radio frequency, can effectively solve the problems of too many feeders, difficult construction and difficult access to site resources, and has become the standard solution for network deployment in the industry.