Centralized radio access network (C-RAN) architecture is a promising way for 5G RAN network which is capable of decreasing power consumption, saving machine room, promoting collaborative radio, etc. Compared with the traditional distributed radio access network (D-RAN), the distributed units (DUs) are placed at one central office and the corresponding distance from active antenna unit (AAU) to DU is extended to 10 km for the main scenario of 5G C-RAN front-haul network. In this centralized scenario, wavelength division multiplexing (WDM) technology would be introduced between AAU and DU to save optical fibers.

Wavelength signals

All optical signals emitted in the networks reached each station. A wavelength division multiplexer at each station was able to separate in parallel the different wavelength signals from the different network emitters. In general, the routing was electronic as in classical networks, using time switching with a selection done through the address coded on the message header. Profiber demonstrated many advantages, in particular, few or no blocking possibilities and either multipoint-to-multipoint link, point-to-point link, or point-tomultipoint link.

Distributed intelligence

At the present time, telecommunication networks are relatively heterogeneous’ New services have to be introduced by traditional and new operators. Profiber see a tremendous growth of the Internet. New services such as video conferencing, entertainment, interactive video training, teleworking, bank information service, data transfer between computers, teledistribution, and generally all ISDN, and broadband networks, need or will need bit rates from 1 to 100 Mbps and above. The new networks require a real flexibility and a kind of distributed intelligence.

Capabilities and flexibility

In principle, in the photonic WDM networks, space, time, and wavelength switching can be added. Thus, a new dimension, profiber allowing for new capabilities and flexibility, becomes available. Interestingly, the aggregate capacity can be increased and the blocking probability (i. e., the probability that all possible routes are already in use at a given time), can be reduced.

Circuit-based switching

The payload doesn’t experience optical-to-electrical or electrical-to-optical conversion between source and destination. The move from circuit-based switching towards packetbased switching has been a general trend in datacom and telecom networks for many years. Indeed, profiber by allowing the sharing of the available bandwidth with a very-fine granularity, using packets results in much better bandwidth efficiency. This becomes particularly true in modern telecom networks, where Internet traffic becomes largely predominant

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