汉信
People now cannot live without advance wireless technologies, mobile phone is the typical example. The using of mobile phone improves our life a lot. However, without strong enough wireless signal, mobile phone cannot work normally. You may find that the signal bars of your mobile phone are less inside some large building or elevator. This is because wireless signal can be weakened by the walls inside a building easily. To ensure strong wireless, solid physical layer connectivity foundation should be installed. Distributed antenna system (DAS) is usually used for both indoor and outdoor environments where wireless converge are poor. To satisfy large volume signal transmission, fiber optic wireless network is deployed with DAS.
What Is DAS?
Distributed Antenna System solves the headache wireless coverage problems for wireless providers. DAS uses many antennas to boost network coverage in places with weak or no signals. In a DAS network, managed hubs are deployed to distribute the signal from base station or feeder cables. DAS can also be built on the existing fiber optic network like FTTx, which can largely decrease the deployment costs. In most large hospital, shopping mall and train station, you can find DAS network.
How to Deploy DAS Based on Fiber Optic?
As fiber optic cable can provide large volume of signals over long transmission distances, combining the DAS network with fiber optic network is regarded as the best solution for high performance wireless network solution in poor wireless coverage places. The following will introduce DAS for both indoor and outdoor applications.
For most indoor applications, DAS is required to be deployed inside a building or several buildings. There is usually a fiber distribution hub (FDH) or server room which is connected to feeder fiber optic cables from service provider. Then, the fiber optic cables installed in the building send signals to customers via antennas deployed in every floor of the building. There might be several antennas in one floor. Thus, fiber optic splitter is usually used to distribute signals to every individual antennas. If the antennas are installed too far away from the fiber distribution hub, fiber optic amplifier should be used to ensure the transmission quality. Usually there will be a fiber cabinet deployed in every floor for better cabling and network management.
Sometime, the feeder signals are from the yagi antennas. This would require the use of low loss copper cables and Bi-directional amplifier (shown in the following picture).
For the outdoor applications, the DAS network can make full use of the existing fiber optic network deployed outdoor. Installers also have a lot of places to install antennas of DAS network, like poles and street lights. The following picture shows the structure of a DAS network combined with fiber optic network. This DAS system uses existing fiber optic network and installs the antennas on the street lights. There are usually fiber splice closures or fiber optic cabinet underground to connect the antennas with the existing fiber optic network.
