It’s now possible to solve interference and other issues without spending countless hours on the road.
Interference has always been a curse for the cellular industry. It degrades network performance, can render a base station or some portion of it unusable and impacts subscribers’ quality of experience. Interference has also historically been incredibly time-consuming and expensive to detect, identify, and eliminate, requiring thousands of truck rolls to cell sites every year. However, as we’ll see, the technology exists today to dramatically simplify and reduce the time and cost required to keep interference in check.
Although the availability of portable test equipment has reduced or eliminated the need to lug hundreds of pounds of benchtop instruments to a site, there has until recently been no way to positively diagnose and fix a problem before an operator dispatches a technician. It’s certainly possible to alert a Network Control Center about a specific RF-related problem, but this does not provide a solution, so information-gathering is still required at the site followed by at least one more “visit”. It is inefficient, time-consuming, and becomes expensive, very quickly.
Adoption of the Common Public Radio Interface (CPRI) designed exclusively for communication between a base station and a remote radio head (RRH) via optical fiber has made it possible to solve this problem through comprehensive monitoring, detection, and analysis.
It couldn’t have come at a better time, as wireless carriers need to dramatically reduce network capital and operating costs while increasing network flexibility. The ability to remotely detect, identify, and diagnose any electrical, optical, or RF problem allows predictive maintenance to be performed, which can potentially reduce the need for truck rolls to cell sites by 40% or more.
That is, while this once required multiple truck rolls, they can now be reduced to one or perhaps even none if the problem originates somewhere other than carrier-owned infrastructure. In this case, the issue can be passed on to the owner of that hardware, costing the carrier little or nothing. Together, these technologies place virtually no limit on the number of sites that can be remotely accommodated. Almost any issue, from interference to failed or failing components, can be immediately detected, identified, and a solution reached without sending a technician to a site.
An excellent example of a system designed for this purpose is SkyRAN, recently introduced by EXFO Inc. that is an end-to-end solution that enables real-time monitoring through diagnosis of both fiber-and RF-related issues. It troubleshoots remotely so that before technicians are dispatched, they have actionable information about the problem, where it is located, and the right resources to solve it, making more efficient use of technicians’ time. SkyRAN is scalable to networks of almost any size to accommodate growth.
Access to RF signals as I/Q data is provided via the CPRI link between the RRH and Baseband Unit (BBU) whether the BBU is in the equipment shelter or a BBU hotel miles away. RF monitoring software continuously monitors and records system performance and provides both reports and alerts about out-of-spec or otherwise undesirable conditions such as PIM or high RSSI. At the control center, SkyRAN software runs on a Windows-based computer to deliver a visual representation of all elements of the fronthaul network to the tower top. The displays are extremely comprehensive yet easy to interpret, making it possible to make decisions and assign resources rapidly.
EXFO’s OpticalRF technology that provides high-resolution RF spectrum analysis enables some of SkyRAN’s most important capabilities. It can simultaneously display multiple antenna carriers either side-by-side or overlaid on each other and has performance typical of dedicated, high-end benchtop instruments. The system also includes EXFO’s iOLM application that simplifies OTDR testing by eliminating the need to configure parameters or analyze and interpret multiple complex OTDR traces. Its algorithms dynamically define testing parameters and locate and identify faults with a single one-button command.
The cellular industry has used the same basic approach for dealing with interference and other network issues for a quarter century, but it is wholly inadequate today and will be intolerable in the future. Fortunately, massive advances in technology now allow solutions like SkyRAN to comprehensively address mobile network performance, including complex RF challenges, remotely, without resorting to multiple truck rolls.
Learn more about SkyRAN here.
