MindMap Gallery Optical access technology
Mind map of optical access technology, optical access network OAN; focusing on solving the effective access of narrowband services such as telephones, while also solving the problem of adjusting broadband access services such as data services and multimedia images; OAN generally refers to the feeder between the switch and the user A system in which some or all of the cable sections, wiring sections and drop-in lines are accessed by optical fiber
Edited at 2023-10-18 19:25:14This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Optical access technology
Overview of optical access technology
basic concept
Optical access network OAN; focuses on solving the effective access of narrowband services such as telephones, and also solves the problem of adjusting data services, multimedia images and other broadband access services; OAN generally refers to the feeder section, wiring section and lead-in line between the switch and the user. A system that is partly or entirely connected by fiber optics
Reference configuration: G.902 with UNI SNI Q3
Optical fiber access network consists of: central office optical line terminal OLT user-side optical network unit ONU optical distribution network ODN optical fiber
Features of optical access network: point-to-multipoint transmission system, medium sharing; downlink broadcast (time division multiplexing to transmit cell stream); uplink: various multiple access technologies
Optical access network basic network unit
OLT: [Core functions] Digital cross-connect function, transmission multiplexing function (G.902 has no switching function!!!) and ODN interface; [Business function]: Service port function; [Public layer function]: Power supply and OAM function
ODN: Provides optical transmission media for the physical links of ONU and OLT
ONU: [Core functions] User and business multiplexing functions, transmission multiplexing functions, ODN interface functions [Business functions] Provide user port functions [Public layer functions] Power supply and OAM functions
Transmission technology of optical access network: [Space Division Multiplexing]: Use one optical fiber for uplink and downlink respectively; [Time Division Multiplexing]: Inherent problem: Each ONU is not at the same distance from the OLT -> the transmission delay is different -> reaches the OLT The phases are different, so the OLT has the following requirements: perfect ranging technology, etc.; [Wavelength Division Multiplexing]
Classification of optical access networks: passive optical network PON (ODN is composed entirely of passive components), active optical network AON (features: large transmission capacity, long transmission distance, mature technology, troublesome power supply to active devices)
Applications of optical fiber access network: Fiber to the roadside FTTC Fiber to the building FTTB Fiber to the home/office FTTH/O
PON system
[Transmission between OLT and ONU]: TDM/TDMA; [Downlink channel] Time Division Multiplexing [Uplink channel] TDMA
Key technologies of PON: ranging technology, fast bit transmission technology, burst signal transmission and reception, scrambling technology, medium access control (MAC) technology
APON
APON Overview
Passive optical fiber network for ATM; supports multi-service, multi-bit access and broadband, transparent data transmission; standard specification: ITU-T G.983
G.983 basic features:
Based on ATM cells
Supports symmetric and asymmetric working modes: 155.520Mb/s 155.520/622.080
Two-way communication: wavelength 1310nm area (space division multiplexing/double fiber one-way); upper letter: 1310 lower: 1550 (wavelength division multiplexing/single fiber two-way)
[Maximum distance without amplifier]: 20km; [Up to 32 user optical branches] [Use wavelength allocation to increase business capabilities]
Transmission technology: TDM is used in both uplink and downlink
APON key technologies: ranging and fast bit synchronization technology
System structure of APON based on TDMA
Downstream direction: Adopt point-to-multipoint broadcast mode; ATM cells from the ATM switch-->OLT-->OLT assemble them into frames-->broadcast mode, and send them to the downlink channel using the 1550 wavelength zone.. ....
Upstream direction: burst mode; the user data of the network terminal is adapted to the ATM format by the corresponding AAL --> ONU assembles the ATM cells into the APON format, passing the 1310nm wavelength at a rate of 155.520
APON frame structure
Downlink: Continuous time slot stream consists of 155.520Mbit/s 56 ATM cells 2 PLIAM (Physical Layer Operations, Management and Maintenance) cells; 622Mbit/s 224 ATM cells 8 PLOAM cells
Uplink: using TDMA method 53 ATMs
EPON
Overview
The physical layer uses PON technology and the link layer uses Ethernet protocol; low cost, high bandwidth, strong scalability, flexible and fast service reorganization, compatibility with existing Ethernet, and convenient management
EPON basic indicators: single-mode fiber, at 1000Mbps rate, splitting ratio 1:32, transmission distance 10km; single-mode fiber, 1000Mbps rate, splitting ratio 1:16 20km; G.652 single-mode fiber; uplink: 1310nm, downlink: 1490nm
Basic features of EPON: The signal transmission between OLT and ONU is based on IEEE 802.3 Ethernet; the transmission line rate is 1250Mbit in both uplink and downlink; based on the MPCP mechanism of the MAC control sublayer; logical splitting ratio: 1:32 (1:64)
System structure: two-way communication method: single fiber two-way (forced) wavelength division multiplexing, uplink 1310nm, downlink 1490nm. In addition, 1550nm downlink can be superimposed on this core to transmit analog TV signals.
data transmission
EPON transmits variable-length Ethernet frames (64~1518 bytes), and EPON frames are timed long frames (2ms)
Downstream: A continuous data stream of fixed-length frames (2ms) containing multiple Ethernet frames (time slots) of different lengths, header (OUN identifier and synchronization header) + check part
Uplink: TDMA technology, frame length 2ms
working principle
Downstream: broadcast mode
ONU registration successfully assigns a unique LLID
Add an LLID before each group starts
The OLT receives data and compares it with the LLID registration list. When the ONU receives data, it only accepts frames or broadcast frames that match its own LLID.
Uplink; TDMA mode
The OLT compares the LLID registration list before receiving data.
The ONU sends data frames in the time slots uniformly allocated by the central office equipment.
The allocated time slots compensate for the distance difference between each ONU and avoid collisions between ONUs.
10G EPON
IEEE802.3av
asymmetric
Downstream: 10Gbps Upstream: 1Gbps
Downlink center wavelength 1577nm Up: 1310nm
symmetry
Downstream: 10Gbps Upstream: 10Gbps
Downlink center wavelength 1577nm Up: 1270nm
GPON
Overview
Gigabit passive optical network; downlink: 2.488Gbps uplink: 1.244Gbps; adaptation protocol ITU-T G.7041; multi-service and multi-bearer; currently the most ideal broadband optical fiber access network technology
Why choose GPON
Three major advantages: long distance; high bandwidth; light splitting characteristics
The best solution for triple network integration
GPON standards are complete, comprehensive business support is good, and technical requirements are high; it is the choice of major global operators
Performance parameters
Asynchronous transmission rate: 0.15552Gbps 0.62208Gbps 1.24416Gbps 2.48832Gbps
Maximum physical distance: 20km
Split ratio: 1:64 1:128
Standard protocol: ITU-T G.984.1 G.984.2 G.984.3 G.984.4
Principle--data reuse
WDM single fiber bidirectional (mandatory); upper: 1310nm lower: 1490nm
Two multiplexing methods are used to separate the incoming and outgoing signals of multiple users on the same optical fiber.
The downstream data stream uses broadcast technology, with a frame length of 125um; all ONUs can receive the same data, but different ONU data are distinguished by ONUID. ONUs receive their own data through CITS
The upstream data stream uses TDMA with 9120 time slots per frame.
protocol stack
Reference model: Transmission convergence sublayer GTC: GTC framing sublayer, GTC adaptation sublayer; physical media layer (PM layer)
GPON packaging method
5-byte frame header: PLI (12-bit payload length) Port-ID (12 bit provides 4096 different ports) PTI (3-bit payload type highest bit OAM information; second highest bit indicates whether user data congestion occurs; lowest bit 1 indicates frame end)
L byte payload
Basic protocol concepts
[1] T-CONT transmission container; divided into four categories: [2] Fixed bandwidth, guaranteed bandwidth, guaranteed/non-guaranteed bandwidth, best-effort forwarding, hybrid mode [3] T-CONT is mainly divided from the perspective of bandwidth rather than service type ;【4】Each T-CONT is identified by Alloc-ID
DBA dynamic bandwidth allocation, using centralized control
Gemport: a channel that carries flows; GEM is similar to ATM and is also oriented to virtual connections.
Reuse diagram
frame structure
Physical layer: Both uplink and downlink are fixed-length TDM frames 125us
frame structure
GPON frame information
Data information
There are two types of downlink frame payloads: ATM cells and GEM cells.
Uplink: ATM cells, GEM cells, DBA frames
Control information: OMCI EOAM PLOAM
Data information is all in the payload, while some control information is in the payload and some in the frame header.
10G GPON,G.987
Asymmetric: XG-PON1 up: 2.5Gbps (1270nm) down 10Gbps (1577nm)
Symmetry: CG-PON2 Up and down: 10Gbps
APON GPON EPON comparison