MPLS in Mobile Backhaul Networks Framework and Requirements ...

MPLS in Mobile Backhaul Networks Framework and Requirements Technical Specification IP/MPLS Forum 20.0.0
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synchronized according to it (e.g. in case of an indoor operation). The external reference synchronization
signals need to incorporate both accurate frequency and time.
Under all circumstances, the relative phase difference of the synchronization signals at the input port of
any Node B in the synchronized area shall not exceed 2.5 usec. This requirement translates to an
equivalent maximum phase difference compared to UTC requirement of less than 1.25 usec (half the 2.5
usec budget).
(iii) Transport Channel Synchronization:
The Transport Channel (or L2) synchronization provides a L2 common frame numbering between
UTRAN and UE (frame synchronization between the L2 entities). It defines synchronization of the frame
transport between RNC and Node B, considering radio interface timing. DL TBS (Transport Block Set)
transmission is adjusted to fit receiver by adjusting the DL TBS timing in the upper node. UL TBS
transmission is adjusted by moving the UL reception window timing internally in the upper node.
(iv) Radio Interface Synchronization:
The Radio Interface synchronization relates to the timing of the radio frame transmission (either in DL
[FDD] or in both directions [TDD]). FDD and TDD have different mechanisms to determine the exact
timing of the radio frame transmission and also different requirements on the accuracy of the timing.
In FDD Radio Interface synchronization is necessary to assure that the UE receives radio frames
synchronously from different cells, in order to minimize UE buffers.
In TDD Radio Interface synchronization refers to the following two aspects:
Inter-cell Synchronization that is used to synchronize radio frames within neighboring cells in order to
minimize cells cross-interferences, to allow frame
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October 2008 Page 40