ADTRAN Total Access 300 Series Installation And Maintenance Manual page 20

Total Access 300 Series Single Family Unit ONT Installation and Maintenance Guide
on splitting optical wavelengths to end points along the way. These passive components, such
as splitters and coupler devices, work by passing or restricting light and do not require power
to transmit data.
In a PON, a single fiber can be run from the serving exchange out to a subdivision or office
park. Then, individual fiber strands can be run to each building. Also, serving equipment can
be split from the main fiber using passive splitters/couplers. This allows one fiber cable from
the exchange to the customer to be shared by many customers. This dramatically lowers the
overall costs of deployment for Fiber To The Premises (FTTP) applications.
In this type of network, the subscriber's voice, video, and data devices are connected to the
GPON via the ONT. The ONT translates IP data and analog voice into GPON Encapsulated
Method (GEM) frames and combines/splits the signal with analog and/or digital video to
and from the OLT. The signal is split/combined at the OLT similar to the ONT.
GEM is based on the SONET/SDH Generic Framing Procedure (GFP) for handling time
division multiple access (TDMA), ATM and Ethernet based traffic without additional encap-
sulation protocols.
Signal transmission from ONTs to the OLT use a type of TDMA. TDMA is a technique used to
frame channels of data. In this technique, data communication sessions originating from
multiple points are transmitted in turn. Each data communication session is assigned a time
slot in the TDMA frame and transmits (or accesses that time slot) only at that time.
To allow for the transmission of downstream and upstream traffic on a single fiber, different
wavelengths are used for each direction. Downstream traffic uses 1490 nm while upstream
traffic uses 1310 nm. For RF TV distribution, a second downstream wavelength of 1550 nm is
used. RF uses 1610 nm for the upstream return path.
Downstream data is broadcast from the OLT to all ONTs. Each ONT processes the data
destined to it by matching the address at the protocol transmission unit header. The
downstream PON signal is broadcast to up to 32 ONTs with a data rate of 2.5 Gbps for voice
and data, plus the additional video overlay wavelength division multiplexing (WDM) signal.
In the upstream direction transmission of data must be coordinated between each ONT to
avoid collisions due to the shared media of the ODN. Data is transmitted according to control
mechanisms configured in the OLT. The aggregate upstream rate is 1.25 Gbps.
HPNA is an alliance of leading technology companies that promote the adoption of a high
performance existing-wire home networking standard for applications such as triple-play
service. HPNA features help guarantee Quality of Service (QOS), remote management and
diagnostics. It operates up to 320 Mbps over both coaxial and phone wires.
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