Service Manual

GSM-205-323
NIU
31st Oct 01
Technical Description: Horizon macro indoor
68P02902W07-B
CONTROLLED INTRODUCTION
Tech. 6–19
Distance
measurement
The NIU provides the ability to perform network distance delay measurement on
either of the two network links. Measurement can only be performed on one link
at a time.
Three modes of operation are possible:
 Mode 1. A pattern is transmitted in a selected network timeslot and the
corresponding receive timeslot is monitored for its return. The delay is
measured to an accuracy of ± 488 ns. The pattern is transmitted on the
6.12 second reference signal.
 Mode 2. The receive link is monitored for the pattern. When received the
pattern is transmitted back in the next frame. The time between receipt
and transmission of the pattern is measured to an accuracy of ± 488 ns.
 Mode 3. The receive link is monitored for the pattern. When it is detected
a strobe is generated for the MCUF sync block.
Radio signalling
links (RSLs)
The radio signalling links (RSL) to the BSC from the main processor on the
MCUF are 64 kbit/s LAPD links. The LAPD encoding of this RSL data is
performed on the NIU by the NIU control processor.
The RSL links between the MCUF and NIU must be sent as follows:
 RSL link 1 is embedded in the NIU control link; that is, it will be in timeslot
0 of link 0 to the NIU. This link is important for initialization.
NOTE
When the NIU is on a network link to a BSC or another
BTS, the RSL can be placed on either link on any default
timeslot other than zero.
 RSL link 2 is on a different timeslot from that used for the network
connection.
The NIU supports a maximum of two RSL links. The RSL links may both be on a
single network link or shared between the two network links.
The NIU hardware supports switching for 64 k and 16 k LAPD channels.
T1 NIU need to
set link type
T1 NIUs and E1 NIUs cannot be interchanged. A T1 link line consists of 24
timeslots as opposed to 32 timeslots for an E1 link line. A T1 link generates
specific T1 alarms, referred to as Red alarms. A T1 NIU supports the same MSI
type of device transitions as an E1 NIU.
The OMC-R operator should set the link type or it will default the site to an E1
system. In ROM it is set by a ROM-only MMI command. In RAM it is a database
parameter set by a chg_element command.
The RSL default timeslots are the same for a T1 NIU and an E1 NIU. The basic
mechanism for communicating and configuring is also the same.