Among the technological hurdles the industry faces while preparing for 5G, one of the most challenging is providing a network timing source that is accurate, stable and reliable enough to do more work, faster, over tighter channels than was possible with prior 4G networks that already had tight timing requirements. With 10 to 20 times more radios than 4G, the coming generation of 5G networks will have a much smaller latency budget between radios. Plus, the higher timing precision of 5G networks must be achieved even as this much larger number of radios, in less expensive housings and with less thermal and mechanical protection, must be pushed to locations with significantly lower environmental controls, including telephone poles and lampposts beside busy highways where they will be subjected to heat, vibration and rapid temperature shifts.
These and other 5G deployment challenges are being solved with the latest MEMS timing architectures that provide an alternative to earlier quartz crystal-based oven-controlled oscillator (OCXO) technology that had previously been used to deliver an accurate timing source. MEMS OCXOs overcome the limitations of quartz OCXOs while delivering new capabilities that will help usher in a new set of best practices for deploying 5G infrastructure in the harsh environments where this radio technology must operate.
Tighter timing in harsher environments
As mobile operators move into 5G and edge computing, they require much tighter time synchronization in the radio equipment, which has necessitated the use of OCXOs. Prior to 5G, OCXOs were deployed in a well-controlled environment. Now, the computing, core network, and radio will be collapsed into a 5G system that may be deployed in an uncontrolled environment such as a tower, rooftop, and lamppost. The OCXOs will be exposed to vibration and temperature extremes in this environment, without the benefit of the thermal and mechanical protection that was provided with earlier 4G radio housings. This requires an evaluation of the benefits of MEMS and quartz timing technologies for implementing the critical functionality of a locally derived timing clock.