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In Sync
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Sync over
Packet for the implementation of WiMAX
The
IEEE 802.16 Worldwide Interoperability for Microwave Access (WiMAX)
standard is rapidly being positioned as the
core technology for
next-generation data centric broadband mobile wireless applications.
Designed for providing QoS, WiMAX can be used for the implementation of
a transport network suitable for real-time applications like Internet
access, streaming services, interactive
gaming, video-on-demand,
and voice-over-IP (VoIP) services. With the introduction of Mobile
WiMAX (IEEE 802.16e), a new foundation had been set for the emerging 4G
networks.
WiMAX is supporting both FDD and TDD modes of operation. However, TDD
is the preferable mode
of operation for data centric applications and for Mobile WiMAX as its
spectral efficiency is higher than FDD. In addition, TDD is easier to pair with
smart-antenna
technologies, it provides
enhanced flexibility, and it is assymetrical in nature.
When using TDD mode, the whole spectrum is alternately used for
transmit (Tx) or for receive (Rx). Therefore, in order to avoid
interferences between Tx and Rx, the IEEE 802.16 has defined two guard
bands: TTG - Transmit/Receive guard band and RTG - Receive/Transmit
guard band.
For that reason, WiMAX and in particular IEEE 802.16e have the most
demanding synchronization requirements. WiMAX base stations requires
three level of synchronization: Frequency, Phase, and Phase Lockup.
WiMAX phase lockup requires that all base stations will be synchronized
to one another within ±1usec in order to
avoid adjacent base stations
interferences.
Currently, the solution for maintaining this strict synchronization
performance is by using a GPS receiver at each WiMAX base station. A
new cost effective solution is now becoming available with the emerging
IEEE 1588v2 standard which supports all three levels of synchronization
required by TDD as well as the required tight synchronization
performance.
A new approach for
clock synchronization implementation over packet is required to
leverage the IEEE 1588v2 capabilities in order to handle the inherent
Ethernet/IP/MPLS packet network impairments in
order to meet clock synchronization performance as defined by
the IEEE 802.16 standard. IPCLOCK IPC2713
Sync over Packet Engine (SoPE) for IEEE 1588 is a the solution for the implementation of WiMAX base
station synchronization over Ethernet/IP/MPLS networks.