User guide
Data Rate (Mbps) Base Data Rate Local CGB Divider
3072.0 6144.0 2
4915.2 9830.4 2
6144.0 6144.0 1
9830.4 9830.4 1
Supported Features for CPRI
The CPRI protocol places stringent requirements on the amount of latency variation that is permissible
through a link that implements these protocols.
CPRI (Auto) and CPRI (Manual) transceiver configuration rules are both available for CPRI designs. Both
modes use the same functional blocks, but the configuration mode of the word aligner is different
between the Auto and Manual modes. In CPRI (Auto) mode, the word aligner works in deterministic
mode. In CPRI (Manual) mode, the word aligner works in manual mode.
To avoid transmission interference in time division multiplexed systems, every radio in a cell network
requires accurate delay estimates with minimal delay uncertainty. Lower delay uncertainty is always
desired for increased spectrum efficiency and bandwidth. The Arria 10 devices are designed with features
to minimize the delay uncertainty for both RECs and REs.
Word Aligner in Deterministic Latency Mode for CPRI
The deterministic latency state machine in the word aligner reduces the known delay variation from the
word alignment process. It automatically synchronizes and aligns the word boundary by slipping one half
of a serial clock cycle (1UI) in the deserializer. Incoming data to the word aligner is aligned to the
boundary of the word alignment pattern (K28.5).
Figure 2-96: Deterministic Latency State Machine in the Word Aligner
Deserializer To 8B/10B Decoder
Clock-Slip
Control
Parallel
Clock
From RX CDR
Deterministic Latency
Synchronization State Machine
When using deterministic latency state machine mode, assert rx_std_wa_patternalign to initiate the
pattern alignment after the reset sequence is complete. This is an edge-triggered signal in all cases except
one: when the word aligner is in manual mode and the PMA width is 10, in which case
rx_std_wa_patternalign is level sensitive. This signal must be asserted for at least 2 parallel clock cycles
to allow synchronization of the word boundary.
2-270
Supported Features for CPRI
UG-01143
2015.05.11
Altera Corporation
Implementing Protocols in Arria 10 Transceivers
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