Thanks to recent expansion of 4G LTE networks, mobile carriers are able to provide more services than ever before. Wireless telecommunication customers have quickly come to expect better performance from their networks in response to the widespread availability of LTE services, demanding faster data speeds and consistent uptime. To meet consumers' ever-increasing expectations, telecom operators must find a way to tackle a long-standing obstacle to network performance: passive intermodulation.
PIM has been a force to be reckoned with in the telecom sector for years, but the growing complexity of mobile networks has made it more disruptive than ever. A JDS Uniphase white paper released last year explained that although commercial mobile communications services typically use licensed spectrum to avoid encountering interference with other networks, PIM can generate additional frequencies that clog transmission channels. Various elements can cultivate the creation of PIM, including corroded materials and the presence of certain metals. These seemingly trivial matters can add up to performance problems for network operators if they are not identified and corrected. As test equipment manufacturer Anritsu noted, these issues can have a noticeable effect on the end-user experience.
"When PIM products fall within the receive band of a cell site radio, they make the receiver less sensitive to weak signals that limits receive coverage," Anritsu stated. "This increases the bit-error-rate and creates more dropped calls. If the connection is for data, interference from PIM creates more error protection bits and resends, which causes a lower overall data rate. In some cases, PIM can even cause receiver blocking, shutting down the sector."
LTE expansion drives need for PIM testing
As mobile networks evolve and become more complex, the likelihood of PIM emerging grows significantly. In many instances, carriers have built their LTE structures on top of existing environments. The interaction of these disparate systems can lead to the creation of PIM and adversely affect the delivery of services. Wireless operators may even find that their recently launched LTE networks offer only marginal – if any – performance benefits over previous models. Furthermore, the litany of network problems resulting from PIM may drive customers away, cutting into the revenue streams of mobile carriers.
Due to the costly ramifications of PIM, sources claim it's critical that wireless operators conduct thorough testing to eliminate PIM issues. LBA Group's David Horn explained that effective PIM testing is a complex, multistep process. Horn said carriers should begin by running computer analysis to identify locations along their networks that may be conducive for PIM development. From there, technicians need to go on-site to conduct a more thorough investigation. Horn noted that these processes should be handled quickly since mobile users are unlikely to tolerate sluggish performance for very long.
As previously explained by RCR Wireless News, technicians must conduct these processes at a minimum of the base station radio power level. This should help personnel accurately recreate real-life network conditions and activity. By adhering to the principles of PIM testing, operators can look to eliminate the interference that prevents them from maximizing network capabilities.
