A new approach to deploying the centralized RAN (C-RAN) can overcome the economic roadblocks that have limited its adoption, until now. So service providers can use this streamlined, efficient mobile network architecture to resolve spectrum scarcity in urban neighborhoods.
Mobile broadband usage is projected to double annually and grow to eight times current rates by 2020 according to a Nokia Bell Labs Consulting report,. As a result, there has never been a more urgent need for CâRAN deployment.
The C-RAN opportunity
The C-RAN architecture emerged as a cost-effective way to densify networks and add more cells for greater capacity. Therefore, it addresses the common challenges of building new sites and maintaining service quality in crowded urban areas — such as the expense and difficulty of site acquisition, when power and processing equipment must be installed at the site. And the radio interference that can result when increasing the number and density of cells.
A centralized RAN solves the site cost and acquisition problems by disassembling the site and moving the baseband unit (BBU) to a central location. This approach requires less equipment at the site. And that means each site is smaller, less expensive, and easier to acquire.
The centralized BBU enables performance gains through better coordination of adjacent cells — which lowers interference and improves cell-edge throughput. It also minimizes the need to over-provision the network, because it can take advantage of pooled resources that better balance the traffic load across the network and optimize spectrum usage.
Making fronthaul economically feasible
Until recently, the cost of satisfying strict standards for fronthaul transport has limited C-RAN adoption. That is, the remote radio heads needed dedicated fiber connections to the centralized BBU, in order to meet Common Public Radio Interface (CPRI) and Open Base Station Architecture Initiative (OBSAI) requirements for bandwidth, low latency, and minimal jitter.
But point-to-point fiber didn’t make economic sense, except in rare urban areas with abundant dark fiber or where the government subsidizes fiber installation, as in some Asian markets.
Now, solutions are available that make it economically feasible for mobile service providers to take advantage of the C-RAN. The key is to increase fiber utilization using optical wave-division multiplexing (WDM) with sufficient performance to meet CPRI/OBSAI requirements, while enabling TCO savings. The Nokia Mobile Fronthaul solution, for example, can reduce TCO by up to 30 percent, according to a Bell Labs Consulting business case that compared point-to-point fiber with a WDM-based approach.
In addition, the optical fronthaul portion of the network must be vendor agnostic, since most operators have a mix of RAN vendors today. Solutions having wavelength translation capability enable easy roll out, without requiring any retrofit of the RAN network. The solution should also include robust OAM capabilities, providing fiber link and per-channel-power monitoring, so operators can proactively manage the network and uphold SLAs in support of different business models.
For more information on mobile fronthaul and the centralized RAN, see the related materials we’ve provided.