For the introduction of femtocells in the telecom market the distribution of precise time and frequency is a key challenge for a mass deployment in the heterogeneous networks.

The high cost for achieving the required accuracy has been a barrier for this emerging consumer market.  The operator defined price target of US$100 is easily upset by the cost of the clock reference technologies alone. New products based on IEEE 1588 technology, like the Imsys IM3240, intend to overcome this. 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. 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.

Precise time with nanosecond accuracy, synchronized to UTC (Coordinated Universal Time), is made possible by the Precision Time Protocol (PTP) 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. Synchronized time can now become commodity for use in networked systems. An IM3240 based Edge Grand Master, or EGM for short, can act a local area network service provider of time and frequency to clustered small cell base stations in the New Generation Mobile Networks.

The functionality is delivered by the IM3240, an Application Specific Controller with an integrated hardware Time Stamp Engine (TSE) for Ethernet based protocols. In implementing the IEEE 1588 protocol software the IC delivers highest accuracy, with a peak-to-peak error of 11 ns in the timestamping of PTP messages, compared to the GPS input reference. The unparalleled features of the IM3240 makes it a first choice for new generation mobile networks as they now move indoors.

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. The value of the IP network time and synchronisation 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.

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