The shift from voice to data-centric mobile networks has resulted in a move from traditional TDM services to a wide-scale adoption of Carrier Ethernet in mobile backhaul. Without any legacy TDM-links, however, base stations risk being isolated from traditional synchronization references. As mobile operators increasingly deploy 4G radio access technologies and depend on accurate delivery of synchronization, they are now seeking advanced solutions that not only accurately deliver the required timing information over packet networks but also provide assurance regarding its availability.
Mobile services are dependent on timing and base stations need a stable frequency reference to support mobility. Actually, operators are confronted with a broader, two-part challenge. First, they must replace their TDM-based clock function with a suitable packet clock. Secondly, as they deploy advanced LTE or CDMA technologies, they eventually must expand that packet-clock capability so that it can distribute not just the frequency reference but also phase and time-of-day information. The alignment of clock frequency enables base stations to stay within the allocated spectrum, avoid interfering with other base stations and provide proper hand-off between them. While the frequency requirement is ever present, advanced LTE and CDMA base stations additionally require phase and time-of-day alignment of all clocks to switch between uplink and downlink transmission at the same instant.
The availability of accurate timing information at each cell site is therefore a crucial factor for proper operation of the radio access network. Consequently, mobile operators want to understand the actual performance of the timing network providing this information. Delivering synchronization is not enough for enabling stable operation of the radio access network. Assured delivery with guaranteed quality of service metrics is a must – no matter whether operating the backhaul network by oneself or leasing backhaul connectivity and timing services from independent service providers.
The ability to consistently monitor and accurately test and troubleshoot the synchronization infrastructure is mandatory for assuring clock accuracy. Assured delivery with guaranteed quality of service metrics is a must not only for data services but also for timing services. As timing information potentially traverses different technologies and operator networks, service assurance mechanisms as implemented in Carrier Ethernet are required. Network timing behavior is not a stationary process. It is subject to dynamic conditions and changes over short term and longer term. Appropriate tools are required for cost-effective and time-efficient end-to-end management of the synchronization network during all phases of its lifecycle – installation, turn-up testing, monitoring and troubleshooting. Operators want to identify potential problems before they cause outages.
Integrating a complete synchronization network management platform with strong emphasis on predictability and quality assurance into traditional network management solutions reduces the number of different tools required and therefore complexity. A rich implementation of support tools allows operators to display the synchronization network topology and continuously monitor and test the quality of the delivered timing signal. It provides functions to predict and analyze quality impairments, therefore assuring a robust and reliable delivery of synchronization.