Cloud RAN – emergence in heterogeneity

April 16, 2014 //By Harpinder Matharu, Xilinx Inc
Wireless infrastructure network is going through a critical phase of technology evolution where a slew of different equipment form factors are being rolled out to meet perpetual growth in demand for capacity. All these solutions are gravitating towards maximising the potential of precious and limited spectrum resource.

While 3gpp standardisation efforts are devising ways to pack more and more bits into available spectrum within the capacity constraints governed by Shannon’s law, wireless radio network is on the move to create topologies that allow less and less number of users to share more and more of the available spectrum. There are two major macro trends that are splitting the network into completely opposite directions.

The first macro trend is pushing the network to deploy an underlay of 10’s of small cells per macro base station to add micro cells within a macro cell to initially improve coverage and then deliver capacity by serving fewer numbers of users. This trend simplifies radio access but creates complexity and scale challenges in the backhaul network.

The second macro trend is splitting the base station into a network. This trend simplifies backhaul but adds complexity to the radio access. Cloud RAN and high density base stations are other names of this trend. The move to distributed base stations in terms of remote radio heads has been happening long before the days of cloud.

Success of a distributed wireless network depends not only on a framework that allows adaptation and growth of distributed intelligence within the network via continuous self-learning but also on a solid foundation that allows coordination among the distributed intelligence to launch new services and profitable monetization of the network. Timing and synchronization is a key element of this foundation aside from self-healing, self-optimizing and software defined network functionality. Timing and synchronization dictates the network performance while software defined network eases effective network sharing and virtualization, service deployment and maintenance. Figure 1 shows a traditional base station architecture.

Figure 1: Traditional base station architecture. Click to enlarge.

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