Altera CPRI IP Core - Manual (Page 46)

4–14 Chapter 4: Functional Description
MAP Interface
CPRI MegaCore Function December 2013 Altera Corporation
User Guide
Configuring your IP core with the All mapping mode provides you the flexibility to
modify the mapping mode dynamically, but configuring your IP core with the specific
mapping mode you expect to use generates a smaller IP core.
Basic AxC Mapping Mode
The basic mapping mode supports the LTE/E-UTRA and UMTS/WCDMA
standards. This mapping mode is implemented when you configure and program
your CPRI IP core in either of the following ways:
■ If you select Basic as the value for Mapping mode(s) in the CPRI parameter editor.
■ If you select All as the value for Mapping mode(s) in the CPRI parameter editor
and you program the
map_mode field of the CPRI_MAP_CONFIG register with the
value of 2’b00.
In this basic mapping mode, all of the AxC interfaces use the same sample rate and
sample width. The CPRI IP core supports sample rates of 3.84 × 10
6 through
30.72 × 10 6 (3.84 × 10 6 × 8) samples per second, in increments of 3.84 × 10 6 , and sample
widths of 15 bits and 16 bits. The uplink and downlink sample rates are identical.
In this mode, the map_ac field of the CPRI_MAP_CNT_CONFIG register specifies the
number of active data channels, that is, those that have a corresponding AxC
container in the IQ data block of each basic frame. This number must be less than or
equal to the N_MAP value you selected for Number of antenna/carrier interfaces in
the parameter editor, which is the number of channels configured in the CPRI IP core
instance. The
map_n_ac field of the CPRI_MAP_CNT_CONFIG register holds the
oversampling factor for the data channels. This value is an integer from 1 to 8. The
sample rate—number of samples per second—is the product of 3.84 × 10
6 and the
oversampling factor.
Advanced 1 Don’t Care
Advanced 1
Appendix D, Advanced
AxC Mapping Modes
All 2’b01
Advanced 2 Don’t Care
Advanced 2
All 2’b10
Advanced 3 Don’t Care
Advanced 3
All 2’b11
Table 4–4. Determining the MAP Interface Mapping Mode (Part 2 of 2)
Mapping mode(s)
Parameter Value
Value Programmed in
map_mode field of
CPRI_MAP_CONFIG
Register
Mapping
Mode
Mode Description