
PM7346 S/UNI-QJET
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ISSUE 6
SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE
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The G.751 E3 PLCP frame provides the transmission of 9 ATM cells every 125
μs. The PLCP frame is octet aligned to the 16 overhead bits in the ITU-T
Recommendation G.751 E3 frame; there is no relationship between the start of
the PLCP frame, and the start of the E3 frame. A trailer is inserted at the end of
each PLCP frame. The number of octets inserted is nominally 18, 19, or 20, and
is based on the number of E3 overhead octets (4, 5, or 6) that have been
inserted during the PLCP frame period. The nominal octet stuffing can be varied
by ±1 octet to allow the E3 PLCP frame to be locked to an external 8 kHz
reference. Thus the trailer can be 17, 18, 19, 20, or 21 octets in length.
Figure 15
- E1 PLCP Frame Format
A1
A2
P9
Z4
A1
A2
P8
Z3
A1
A2
P7
Z2
A1
A2
P6
Z1
A1
A2
P5
F1
A1
A2
P4
B1
A1
A2
P3
G1
A1
A2
P2
M2
A1
A2
P1
M1
A1
A2
P0
C1
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
PLCP
Frame Rate
2.375 ms
53 octets
POH
Framing
(3 octets)
The E1 PLCP frame provides the transmission of 10 ATM cells every 2.375 ms.
Thirty of the thirty-two available E1 channels are used for transporting the PLCP
frame. The remaining two channels are reserved for E1 framing and signaling
functions. The PLCP frame is octet aligned to the channel boundaries in the E1
frame. The PLCP frame is aligned to the 125 μs E1 frame (the A1 octet of the
first row of the PLCP frame is inserted in timeslot 1 of the E1 frame).
12.3.1 PLCP Path Overhead Octet Processing
Table 29
- PLCP Overhead Processing
Overhead Field
A1, A2:
Frame
Transmit Operation
Inserts the PLCP frame
alignment pattern (F628H)
Receive Operation
Searches the receive stream for
the PLCP frame alignment pattern.