Synchronization and Deployment Guide
Chapter 5: LAN Based Radio
Synchronization
Below you will find a description of how LAN based radio synchronization works, and what
must be considered when synchronizing.
The latest generation of Spectralink IP base stations support the use of corporate Local Area
Network (LAN) for synchronization of the DECT radios when running software release PCS15C
or later.
In a multi-cell DECT system the base station radios must be synchronized to each other in order
to achieve the optimum handover experience, when handsets are moving around among base
stations. Spectralink supports the synchronization of digital base stations via the wire and IP base
stations via the radio. IP base stations can use the LAN for synchronization as well.
The LAN based synchronization has several advantages over synchronizing via the radio. The
configuration is much simpler because no synchronization chains need to be configured and
maintained. The synchronization is self-healing, because the system itself can handle if any base
station is failing. Finally, the system can be deployed with fewer base stations, because the base
stations are no longer required to be in range of each other.
It may however not be the ideal solution in all cases. LAN based synchronization requires that the
base stations involved in a handover are on the same network segment and the network
deployment (including LAN switches) meets a number of quality criteria.
Precision Time Protocol Background
Precision Time Protocol version 2 (PTPv2) is used to synchronize the radios of the IP base
station via the LAN. PTPv2 is defined in the standard IEEE 1588-2008 and a brief introduction can
be found here:
http://en.wikipedia.org/wiki/Precision_Time_Protocol
PTPv2 is based on a master-slave architecture, where the active master is automatically selected
among the base stations. Each network segment will have one active master and the remaining
base stations will be slaves. If the current master is failing a new one will be automatically selected
without disrupting the current synchronization state.
The PTPv2 datagrams are sent as multicast and transported via UDP on IPv4 or IPv6 or as raw
Ethernet packets without IP.
The LAN based radio synchronization is administrated centrally from the web GUI of the
DECT/IP-DECT Server. The synchronization itself however is handled autonomously by the base
stations, and the server is not involved and hence does not need to be on the same network
segment.
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