Application Note Seamless Communication with Passive Optical Mobile Front and Backhauling D-5129 Introduction A recent survey disclosed that 63% of the mobile users say it’s important to be connected at all time. With the advent of smart devices, cloud services and newer technology for mobile connectivity like advanced LTE, there is tremendous pressure to strengthen the mobile backhaul segment of the network. The copper connections to the towers can no longer suffice leading to increased fiber penetration. Since the revenue per bit for mobile data service is very low, it is really important to deploy a solution that is cost effective in both CAPEX and OPEX and that also represents a future proof technology for seamless communication. The best way would be to leverage the existing fiber infrastructure, such as fiber to the node or cabinet, to provide cost-effective interconnection for small to macro cellular networks. Together with the CWDM and DWDM technology the mobile broadband network can be made timeless and cheap improving the power and space requirements. In this paper an economic passive backhauling method together with a passive fronthauling technology are discussed. Since fiber convergence to mobile network is a demanding application with changing requirements, it is an interesting subject matter for all the mobile service operators. Passive fronthauling and backhauling While fibers are mostly being deployed in the backhaul networks, a new approach of building flexible mobile networks is being pushed forward where fiber is also used from the base station to the antenna, which is called fronthaul. Traditionally, the baseband unit (BBU 1) and the remote radio head (RRH 2) are collocated inside a cabinet close to the antenna and a coax cable is used to connect the RRH to the antenna located at the top of the cell site. With migration to fiber based connection the RRH is placed close to the antenna at the top of the cell site and connected to the BBU using the common public radio interface (CPRI) or open base station architecture initiative (OBSAI) protocol. Fiber overcomes the loss of coax and also excess energy wasted by heating of the copper. Due to the possibility of longer distances, one can design the fronthaul network with centrally located base station at a central office location equipped with a number of baseband equipment for several base stations. While the connection between the each RRH and BBU can be deployed with a dedicated fiber, the most efficient way would be via the employment of WDM over a single fiber. Figure 1: Passive Fronthauling 1 BBU performs signal processing functions and creates the radio signal. 2 RRH converts radio waves to RF signal. Document: D-5129 Rev.A1 Page 1/3
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