Embedded: Precise Time Protocol enables new-generation Ethernet mobile networks
Imsys shows off its implementation of the IEEE 1588 protocol's synchronized time capabilites in its IM3240 integrated circuit.
“ Synchronized time can now become a commodity for use in networked systems,” says Ola Andersson, president and CEO of Imsys Technologies. In October 2008, engineers gathered in Ann Arbor, MI, for the International IEEE Symposium on Precision Clock Synchronization for Measurement, Control and Communication. At a “plug-fest” to test vendor implementations of a new standard called the Precise Time Protocol, most participants were able to show interoperability over a network given their various implementations of the standard. Imsys Technologies successfully participated with two products, the IM3220 and IM3240. The latter is an application specific controller with an integrated hardware time stamp engine (TSE) for Ethernet based protocols .
Precise time with nanosecond accuracy, synchronized to UTC (coordinated universal time), is made possible by the Precision Time Protocol (PTP), or IEEE 1588 version 2. “The Imsys IM3240 integrated circuit can distribute stratum 1 accuracy over the packet-switching Ethernet, with a reference signal from a global positioning system (GPS) receiver. An IM3240 based Edge Grand Master, or EGM for short, can act as a local area network service provider of time and frequency to clustered small cell base stations in the new generation mobile networks,” says Andersson.
While current industry solution providers see challenges in achieving a 100 ns timestamp accuracy, the Imsys technology delivers a 10-fold better performance running from its internal oscillator, says Andersson. “Where existing solutions require an additional switch and an extra IP address from the operator, Imsys can share the IP address with the local network processor in designs with data payloads up to 60 Mbit/s,” he says.
By implementing the IEEE 1588 protocol software, the IM3240 integrated circuit delivers high accuracy, with a peak-to-peak error of 11 ns in the timestamping of PTP messages, compared to the GPS input reference. “The features of the IM3240 make it a first choice for new generation mobile networks as they move indoors,” says Andersson. “In grandmaster mode it will transmit its GPS based reference to other nodes. When operating in slave mode and without a GPS signal, it will use one of the network’s grandmasters as reference.
Andersson says the value of the IP network time and synchronization controller IM3240 is clear when comparing total cost of implementing the Ethernet connection, communication stacks and synchronization in a slave application. As part of the data path it supports up to 60 Mbit/s layer 2 designs in the network, requiring only one IP address for most applications.
“Now system developers of 4G infrastructure have a viable technical solution which also supports their low cost targets. Looking at the development cycle, we can reduce the time for working prototype from months to days due to the high level of integration. The customers can concentrate on the wireless side of things,” says Ola Andersson, Imsys President and CEO.
The IM3240-P40 is an OEM board for developing products for this application. Connected to a low cost GPS receiver with a pulse per second (PPS) output signal, it will prototype a PTP grandMaster quickly. All necessary hardware and software is included. The small form factor (83x50 mm) and design quality of the Imsys IM3240-P40 platform enables compact design and OEM prototyping with a roadmap to optimizations.
Sweden-based Imsys Technologies AB is an fabless semiconductor company that supplies application-specific processors, modules, and tools for embedded applications like the IEEE 1588 version 2. The company offers Internet-enabled reference modules shipped as ready-to-go subsystems as starter kits.
– Edited by Renee Robbins , senior editor
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