CEBus

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OPERA BPL
(c) 2013 R. Newman University of Florida
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What is OPERA?

• Open industry standard for Access PLC
• 1 manufacturer (DS2)
• Incompatible with HP1.0, other 2-30MHz PLC
• Submitted (not selected) for IEEE P1901 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

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Physical PLC Access Network

• HE Head End (master, connects to backhaul)
• R Time Division Repeater (slave/master)
• CPE Customer Premises Equipment (slave)

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Network Reference Model
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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.

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OPERA PHY

• Reed-Solomon
• Mapping
• HURTO (8x) on delimiters, Adaptive on data
• Scrambling
• 4-D Trellis coded modulation (4D TCM)
• OFDM
• 1536 carriers
• IDFT CP insertion - window

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OPERA PPDU

• SOT
• Synch symbol
• Channel reference symbol
• Control and data symbols
• Max of 243 symbols total

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OPERA Frame Control

• Mapped to one OFDM symbol
• 176 information bits
• 16 CRC bits -gt 192 bits
• G(x) 10001000000100001
• RS (12,8,t2) encoding -gt 288 bits
• FC Interleaver (288 bits)

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OPERA Access

• Master/Slave approach
• HE is master over its network
• TDR is slave to upstream HE or TDR
• TDR is master to downstream TDR or CPE
• 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

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MPDU Structure
TA Token announce delimiter Sender, length of
frame BH Burst header Destination, encryption,
FEC, etc.
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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

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Simple Network
HE is Master HE has data for CPE-1 CPE-1 has data
for TDR TDR has data for CPE-2
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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 TDR sends data and token to
CPE-2 CPE-2 returns token to TDR, which returns
it to HE
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Distributor Token
Master has data for slave 2 Each slave except
slave3 has data for master DT can name at most 5
nodes
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DT Message Sequence
Distributor token may have duration, list Each
slave passes token to next slave on list Last
slave returns token to master
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Polling Token
Polling token names polled slaves Slaves send SOT
in slot in order named if have data
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QOS

• Session oriented
• Service class tags imply QoS 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

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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
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OPERA Security

• IEEE 802.11i
• 128-bit AES encryption per CLPDU
• 128-bit AES CBC MIC per CLPDU fragment
• IEEE 802.1x/RADIUS key distribution/AAA