Autumn 2017 Optical Connections Magazine

XXX XXXXX ANDREW COLE OPTIMAL TESTING

The CPRI standard supports various types of network topology to provide for flexibility in network design. NETWORK RELIABILITY Once the network is completed it is critical to test the integrity and continuity of the installation. Care needs to be taken when installing optical fibre to make sure that the joints are properly made and that the installation is free from macro bends and other unwanted events. Test equipment such as Anritsu’s Network Master test includes a FTTA (fibre to the antenna) application for this purpose, allowing individual faults to be identified for a speedy fix. Turn-up testing with the Network Master allows the C-RAN installation to be fully tested prior to connecting to the BBU. The CPRI specification defines a sequence of common set of actions to be performed by two devices connected by a CPRI link. In normal operation the CPRI link is always on and both connected devices should be in either the operation state or the passive state. The Network Master assumes the role of either the radio equipment control or the radio equipment, switches the device under test either to the passive link state or the Operation state, and tests the link accordingly. Andrew Cole is Business Development Manager at Anritsu EMEA Ltd.

is to use optical fibre throughout the installation, but, where it is impracticable to deploy fibre, millimetre-wave transmission over short distances can provide the answer. CPRI INTERFACE The Common Public Radio Interface (CPRI) specification describes a co- operative industry eort aimed at defining a publically available specification for the key internal interface of radio base stations between the radio equipment control and the radio equipment itself. The mobile data trac is carried as I/Q (in-phase and quadrature) data in a user plane. In addition to the user plane, the CPRI interface incorporates a control and management plane and - most importantly - synchronisation. The interface has two main layers: Layer 1 is the physical layer and covers both electrical and optical transmission using time division multiplexing (TDM). Layer 2 supports Layer 1 in-band protocol, where alarms and errors can be analysed to support troubleshooting the network. HDLC (high-level data- link control) provides protocols for transmitting data between points in the network and acknowledges receipt. Mobile data trac is carried as I/Q data, and vendor-specific information provides for further management and control, redundancy etc.

The Anritsu Network Master test equipment

The Fibre Visualiser identifies individual faults as an aid to speedy troubleshooting.

Attendees of this year’s eCOC have the chance to win a fitbit Blaze watch, courtesy of Optical Connections . The watch includes GPS step tracker, a heart rate WIN! mobile ‘phone, using the watch interface. If you are attending this year’s event, visit the Optical Connections stand, #350 and leave your business card. We will select the Fitbit winner and make an announcement in the winter edition of the magazine. monitor and on- screen workouts. Users can also control the music they have on their

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ISSUE 10 | Q3 2017

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