OPERA BPL c 2013 R Newman University of
OPERA BPL (c) 2013 R. Newman University of Florida
What is OPERA? • Open industry standard for Access PLC – 1 manufacturer (DS 2) – Incompatible with HP 1. 0, other 2 -30 MHz PLC – Submitted (not selected) for IEEE P 1901 Access • Developed 2007 by Open PLC European Research Alliance (OPERA) – Consortium of chip designers, OEMs, PLC users, university researchers – European focus • Ethernet class PLC – 200 Mbps raw PHY data rate
Physical PLC Access Network • HE = Head End (master, connects to backhaul) • R = Time Division Repeater (slave/master) • CPE = Customer Premises Equipment (slave)
Network Reference Model
OPERA Protocol Layers • Bridging • Accepts/delivers ethernet frames • Convergence Layer • Converts between ethernet frames and BPL CLPDUs • Sets priority, handles multicast/broadcast • Logical Link Control (LLC) • Sends burst packets • Handles encryption/decryption • MAC • Medium access, management messages • PHY • OFDM modulation, FEC • Management • Handles network parameters, etc.
OPERA PHY • Reed-Solomon • Mapping • HURTO (8 x) on delimiters, Adaptive on data • Scrambling • 4 -D Trellis coded modulation (4 D TCM) • OFDM • 1536 carriers • IDFT – CP insertion - window
OPERA PPDU • • • SOT Synch symbol Channel reference symbol Control and data symbols Max of 243 symbols total
OPERA Frame Control • Mapped to one OFDM symbol • 176 information bits • 16 CRC bits -> 192 bits • G(x) = 1000000100001 • RS (12, 8, t=2) encoding -> 288 bits • FC Interleaver (288 bits)
OPERA Access • Master/Slave approach • • HE is master over its network TDR is slave to upstream HE or TDR is master to downstream TDR or CPE is always slave • Two access approaches • Poll/Select Mechanism • CSMA token • Poll/Select • Master sends to each slave data or distributor frame • Finished by token with (list of) slave(s) to get channel • May have time limit on access interval • CSMA Token • Opens prioritized contention among receivers
MPDU Structure TA = Token announce delimiter Sender, length of frame BH = Burst header Destination, encryption, FEC, etc.
Token Types • • • Token defines frame type Distributor – allocate time to list of slaves Data – allocate to slave (can recurse) Silence – retain control of medium Polling – ask list of slaves if have data TDR polling – to allow TDRs to poll CSMA – open medium to contention Access/Access Reply – for admitting new nodes Non-returnable Clock
Simple Network HE is Master HE has data for CPE-1 has data for TDR has data for CPE-2
Contention-Free Access Master (HE) sends data to slave with downstream token Slave (TDR) sends data to its slave (CPE-1) with token CPE-1 sends data and upstream token back to TDR sends data and token to CPE-2 returns token to TDR, which returns it to HE
Distributor Token Master has data for slave 2 Each slave except slave 3 has data for master DT can name at most 5 nodes
DT Message Sequence Distributor token may have duration, list Each slave passes token to next slave on list Last slave returns token to master
Polling Token Polling token names polled slaves Slaves send SOT in slot in order named if have data
QOS • Session oriented • Service class tags imply Qo. S requirements • 8 Service Classes • VBR/CBR/ABR/Best Effort • Slave makes request • Classify traffic into service class • Flow Master Node does Call Admission • FMN per service class • Give service ID if accepted
CSMA Token End of CSMA PPDU has CSMA token Non-overlapping backoff window ranges for various priorities Random selection of slot from range for priority per sender
OPERA Security • IEEE 802. 11 i • 128 -bit AES encryption per CLPDU • 128 -bit AES CBC MIC per CLPDU fragment • IEEE 802. 1 x/RADIUS key distribution/AAA
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