IP-CPRI Altera, IP-CPRI Datasheet - Page 63

• Manufacturer Part Number: IP-CPRI
• Description: IP CORE - Common Public Radio Interface (CPRI)
• Manufacturer: Altera

Specifications of IP-CPRI

• Software Application: IP CORE, Interface And Protocols, HIGH SPEED
• Supported Families: Arria II GX, Cyclone IV GX, HardCopy IV, Stratix IV
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: na
• Lead Free Status / RoHS Status: na

Chapter 4: Functional Description
Delay Measurement
Figure 4–19. Single-Hop CPRI Configuration Delay Measurement Reference Points
May 2011 Altera Corporation
Delay Requirements
REC Master
cpri_tx_sync_rfp
CPRI V4.1 Specification requirements R-17, R-18, and R-18A address jitter and
frequency accuracy in the RE core clock for radio transmission. The relevant clock
synchronization is performed using an external clean-up PLL that is not included in
the CPRI IP core.
The CPRI IP core complies with CPRI V4.1 Specification requirements R-19, R-20,
R-20A, R-21, and R-21A.
CPRI V4.1 Specification requirement R-20A addresses the maximum allowed delay in
switching between receiving and transmitting on the AxC interface. Because the CPRI
IP core provides duplex communication on the AxC interfaces, this switch requires
only the programming of the relevant AxC interface Tx or Rx enable bit in the
CPRI_IQ_TX_BUF_CONTROL
is required.
Requirement R-19 specifies that the link delay accuracy for the downlink between the
synchronization master SAP and the synchronization slave SAP, excluding the cable
length, be within ±8.138 ns. Requirements R-20 and R-21 extrapolate this requirement
to single-hop round-trip delay accuracy. R-20 requires that the accuracy of the
round-trip delay, excluding cables, be within ±16.276 ns, and R-21 requires that the
round-trip cable delay measurement accuracy be within the same range. Requirement
R-21A extrapolates this requirement further, to multihop round-trip delay accuracy. In
calculating these delays, Altera assumes that the downlink and uplink cable delays
have the same duration.
Figure 4–19
delay measurements for single-hop CPRI configurations.
CPRI requirement R-21 addresses the accuracy of the round-trip cable delay, which is
the sum of the T12 and T34 delays. The T12 and T34 delays are assumed to have the
same duration.
cpri_rx_rfp
SAP
T_R1
T_T4
shows the reference points you can use to determine the CPRI IP core
T_txv_TX
T_txv_RX
Transceiver
and SFP
R4
R1
or CPRI_IQ_RX_BUF_CONTROL register, and no delay calculation
T14
rx_round_trip_delay
optical link
T12
T34
R2
R3
Transceiver
T_txv_TX
T_txv_RX
and SFP
T_R1
T_T4
Toffset
SAP
CPRI MegaCore Function User Guide
cpri_rx_rfp
cpri_tx_rfp
RE Slave
4–39