An Overview of PON Technologies Pu-Chen Mao 3/21/2011

Outline Background G-PON EPON NG-PON Future Studies References

Background (1/3) Access technologies Wireless Copper 802.11, 802.16, etc. Low cost deployment Insufficient capacity for high bandwidth (revenue) applications such as IPTV Copper DSL Point-to-point architecture allows unshared bandwidth Limited distance due to noise Cost of deployment only slightly less than an all-fiber approach

Background (2/3) Fiber Low noise Long reach Topology Tree More cost effective Point-to-point Dedicated fiber plant from CO to subscriber Ring Fault tolerant

Background (3/3) Shared fiber architectures Active Ethernet PON Signals split by electronic equipment PON Signals replicated passively by splitter Higher reliability due to no electronic equipment in outside plant Signal format transparency Can be more flexibly upgraded Requires no electric power source

G-PON Specified by ITU-T G.984 series Began in FSAN consortium in 2001

G-PON Layers

G-PON Transmission Convergence (GTC) Layer Performs adaptation to the physical-medium-dependent (PMD) layer Adaption methods ATM G-PON encapsulation method (GEM) Preferred method Ethernet adaptation TDM adaptation MAC function Coordinates interleaving upstream traffic from individual ONUs

GTC Layer Control functions Defines protocols & procedures for registering & performance monitoring of ONUs Configuration of transport features FEC Encryption Bandwidth allocation

GTC Layer GTC framing sub-layer Downstream frame format 125 us 8 KHz signal for ONU reference clock Physical Control Block (PCBd) Framing, PHY operations, PLOAM fields Message-based protocol for PMD & GTC mgmt. Bandwidth map field for upstream transmission allocation Payload follows PCBd

GTC Layer GTC framing sub-layer Upstream frame format Same as downstream 125 us Physical layer overhead (PLOu) field Preamble & delimiter configurable by OLT Dynamic bandwidth report (DBRu) field for DBA traffic queuing reports from ONUs PLOAM identical to downstream frame DBRu & PLOAM are optional, requested by OLT

GTC Layer GTC TC adaption sub-layer GEM Protocol independent connection-oriented encapsulation for variable-sized packets Virtual connection unit: GEM port 5 byte header Port ID & frame size Frames may be fragmented G.984 specifies transport of Ethernet & TDM over GEM

GTC Layer T-cont Each T-cont aggregates one type of traffic out of 5 classes Composed of multiple virtual port connections

Upstream Bandwidth Allocation Static method Dynamic Method (DBA) Status reporting DBA ONU reports via DBRu field Non-status reporting DBA T-cont utilization monitored by OLT

GTC Control Plane Operated via PLOAM message protocol and embedded OAM Management functions PMD layer management Upstream config, PHY monitoring, generate stats GTC layer management Framing, requesting PLOAM / DBRu, etc. ONU activation Activate ONU, ranging protocol, optical power tuning Encryption management AES, key exchange procedure

G-PON Management G.984.4 specifies the ONT management and control interface (OMCI) OMCI ONU management information base ONT mgmt. control channel protocol (OMCC) Conveys MIB info between ONU & OLT Models equipment configuration, port types, and service types QoS

EPON Ethernet sub-layers

EPON 1 Gb/s bidirectional links 1490 nm downstream 1310 nm upstream 1550 nm reserved for extensions 802.3ah EPON Minimum 1:16 split ratio Up to 1:64 commercially available 802.3 similarities Standard inter frame gap (IPG) Uses same MAC Multi-Point Control Protocol (MPCP) for P2MP connectivity Uses standard Ethernet packets in MAC sub-layer Modified preamble

EPON Downstream

EPON Upstream

EPON ONU Registration MPCP handshake OLT broadcasts GATE message Unregistered ONUs respond with REPORT and REGISTER_REQ OLT approves and replies with REGISTER ONU responds with REGISTER_ACK

EPON Operation OLT controls ONU transmission windows with GATE messages ONU responds queue status with REPORT OLT calculates transmission window length using DBA Synchronized to PON clock with 16 ns resolution counter in MPCP messages OLT and ONU exchange timestamps to measure RTT for upstream scheduling

EPON Frame Downstream preamble Upstream preamble FEC Encryption Logical link ID field specifies the destination ONU ONU filters frames by LLID ONU receives unique LLID assigned by OLT Special value of LLID reserved for broadcast Upstream preamble LLID marks the source ONU Ensure preamble field integrity by CRC One ONU may have multiple LLIDs (virtual ONU) FEC Based on RS(255,239) Frames encoded separately, parity bytes appended to end Encryption AES-based

EPON Management Link layer management OAM OAM using SNMP OLT remotely manages attached ONUs Remote link monitoring OAM Established after discovery process Maintained by periodic messages Remote failures conveyed in flags of OAM msgs. OAM using SNMP

NG-PON Next-generation PON technologies to extend current bandwidth to 10 Gb/s XG-PON by ITU-T 10GE-PON by IEEE 802.3av

NG-PON Direction

10 Gb/s PON

10 Gb/s PONs Similarities of XG-PON & 10GE-PON L-band downstream 1575 – 1580 nm O-minus band upstream 1260 – 1280 Mandatory FEC RS(255, 223) Video overlay 1550 – 1560 nm

10 Gb/s PONs Uniqueness 10GE-PON XG-PON Conflict in EPON 1260 – 1360 nm and 1260 – 1280 nm band used Share overlapping spectrum using TDMA XG-PON 32-bit word aligned framing XGEM extension PLOAM, DBRu, bandwidth allocation, ranging functions as clients to XGEM system, with XGEM becoming the main protocol

Future Studies System architecture, specifications of XG-PON and 10GE-PON Long-reach PON DBA comparison for EPON, GPON, and next-generation PON

References [1] Effenberger, F., et al., “An introduction to PON technologies,” IEEE Communications Magazine, Vol. 45, Issue: 3, 2007 [2] Effenberger, F., et al., “Standardization trends and prospective views on the next generation of broadband optical access systems,” IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 28, NO. 6, AUGUST 2010 [3] Paul E. Green Jr., “Fiber to The Home: The New Empowerment”, Wiley, 2006