Optical
Network Unit( ONU )
ONU (Optical Network Unit) , ONU is divided into
active optical network unit and passive optical network unit. Generally,
devices equipped with network monitoring including optical receivers, upstream
optical transmitters, and multiple bridge amplifiers are called optical nodes.
The PON uses a single fiber to connect to the OLT, and then the OLT connects to
the ONU. ONU provides services such as data, IPTV (i.e. interactive network
television), voice (using IAD, i.e. Integrated Access Device), and truly realizes
“triple-play” applications.
Function
The broadcast sent by the OLT is selectively received. If the
data needs to be received, the OLT needs to receive a response; the Ethernet
data that needs to be sent by the user is collected and buffered, and the buffered
data is sent to the OLT according to the allocated sending window.
The application of ONU can effectively improve the uplink
bandwidth utilization of the entire system, and it can also configure the
channel bandwidth according to the network application environment and
applicable service characteristics to carry as many end users as possible
without affecting the communication efficiency and communication quality, and
improve the network utilization rate and reduce user costs.
ONU interface types and functions
Network port / LAN port (RJ45 port): 100M port (FE) and
Gigabit port (GE) – connect to the computer to access the Internet
Optical port (PON port, namely SC/UPC or SC/APC port): Insert
optical fiber, signal input
Telephone port (RJ11 interface): abbreviated as POTS, VOIP,
Phone, Voice, FXS – even landline calls
TV port: divided into IPTV (Internet TV) and CATV (cable TV),
IPTV is the network port; CATV is the RF port
USB port: generally USB2.0 interface, connect with data cable
WiFi (wireless network):
Single frequency 2.4Ghz (weak signal and wider coverage)
Dual frequency dual band 2.4G/5Ghz (strong signal coverage is small)
ONU equipment types and
usage scenarios
SFU/SBU (SingleFamilyUnit/SingleBusinessUnit): When
the FTTH/FTTO method is used to construct the optical access network, each ONU
only connects to one user. SFU/SBU generally provides 142 FE to EI, and can
also provide 1-2 POTS interfaces to provide narrowband voice services. When
providing services to commercial customers, SBU can also provide a small number
of EI interfaces.
HGU (Home Gateway Unit): Home gateway unit type
ONU, currently mainly used in FTTH occasions, with 4 Ethernet interfaces, 1
WLAN interface and at least one USB interface.
MDU/ MTU (Multi. DwellingUnit/ Multi-TenantUnit): When the FTTB/C method is used to
construct the optical access network, each ONU needs to access multiple
independent users. MDU/MTU can provide 8/16/24 FE interfaces, or 24/48/96 DSL
interfaces, and the home line is Category 5 or twisted pair. In order to meet
the needs of users for voice services, MDU/MTU can also provide a POTS
interface to provide broadband data services and narrowband voice services at
the same time in a 1:1 ratio. In addition, in order to meet the needs of
commercial customers for TDM services, some MDU/MTU can also provide 2/4/8 EI
interfaces.
