Uplink

Click the name of a field from the Uplink pane that is shown below for a description of the field.

1. Uplink AxC Setup

Operating State allows the uplink measurement to be made once the link is connected and the measurement is started.

Selections: Off, On
Default: Off

In addition to the methods described in User Interface Basics, you can also select this discrete setting by clicking the Uplink Operating State icon on the toolbar. If you have selected Disk as the Destination selection, this selection is switched to Off after the uplink test is complete and the measurement is saved to the disk file destination.

AxC selects the antenna carrier to be tested in the uplink mode. Only one carrier is tested at a time in the uplink mode.

Maximum Selection Range: 0 – 23 (see the AxC Selection Limitations table below)
Default: 0

When uplink capture has not been started, this parameter is checked to make sure the AxC selection falls within the valid range. When uplink capture is activated (Run and Uplink Operating State are set to On), this parameter is validated based on current IQ Sample Width, Oversampling Ratio, and CPRI Line Bit Rate.

AxC Selection Limitations Table

The following antenna channels can be selected for Uplink based on the following IQ Sample Width, Oversampling Ratio, and CPRI Line Bit Rate settings:

IQ Sample Width

CPRI Line Bit Rate

614.4 Mbit/s

1228.8 Mbit/s

2457.6 Mbit/s

When Oversampling Ratio = 2:

4

0 – 6

0 – 14

0 – 23

5

0 – 5

0 – 11

0 – 23

6

0 – 4

0 – 9

0 – 19

7

0 – 3

0 – 7

0 – 16

8

0 – 2

0 – 6

0 – 14

9

0 – 2

0 – 5

0 – 12

10

0 – 2

0 – 5

0 – 11

When Oversampling Ratio = 4:

4

0 – 2

0 – 6

0 – 14

5

0 – 2

0 – 5

0 – 11

6

0 – 1

0 – 4

0 – 9

7

0 – 1

0 – 3

0 – 7

8

0

0 – 2

0 – 6

9

0

0 – 2

0 – 5

10

0

0 – 2

0 – 5

 

 

IQ Sample Width defines the number of bits (or width) of the I and Q sample used in the uplink measurement.

Range: 4 – 10
Default: 8

Oversampling Ratio defines the oversampling ratio used in the uplink measurement.

Selections: 2, 4
Default: 2

Overflow errors occur when the CPRI RE Test solution is not able to transfer the captured data to the selected Destination fast enough. When this error occurs, the uplink is turned off because the CPRI RE Test solution is unable to capture additional data.

Frame Packing Option identifies the method for unpacking each antenna carrier sample from the CPRI frame. Refer to the Frame Packing Option description in the Downlink pane for specifics on how each frame was packed before transmission.

Selections: Packed, Flexible
Default:
Packed

The Flexible method unpacks each sample from the CPRI frame using a specific word address and bit address as the starting position of the sample data, these addresses (Word Address and Bit Address) must be identified if Flexible is selected.

The Packed method finds the sample data starting position automatically based on the AxC selection.

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Word Address (along with the Bit Address) is used to identify the starting address that the software uses to unpack the antenna carrier output sample from the CPRI frame. This is only used when the Frame Packing Option is set to Flexible.

Range: 1 – 15
Default: 1

Bit Address (along with the Word Address) is used to identify the starting address that the software uses to unpack the antenna carrier output sample from the CPRI frame. This is only used when the Frame Packing Option is set to Flexible.

Range: Even address numbers within these ranges based on the line bit rate:
614.4 MB/s: 0 – 6
1228.8 MB/s: 0 – 14
2457.6 MB/s: 0 – 30

Destination identifies the method used to view the test results of the uplink measurement.

Selections: Disk, VSA, BER
Default: Disk

Disk File allows you to enter a binary file name and the PC directory to which the W-CDMA data file is saved. This is only applicable when Disk is identified as the Destination selection. You may enter the complete path and file name in the field or you may click in the field and then click this icon () to open a Save File As dialog box.

Number of Samples limits the number of waveform samples that are saved to the disk. This is only applicable when Disk is identified as the Destination selection.

The maximum file size will be limited by the available physical PC RAM. Of the available RAM, 75% will be allocated for N5120A operations.  Of the memory allocated, 87.5% will be used for the uplink data capture.  

Example

Here’s an example for a PC with 1 GB RAM:

(1000 MB – 300 MB (OS usage) ) * 0.75 = 525 MB allocated for the CPRI application

525MB * 0.875 = 459.37MB for uplink capture

Rate

Data per Frame

Frames

Time

614.4

562.5 kB

836

8.36 seconds
(459.37 * 10242) / (562.5 * 1024) = 836 frames
(1 frame = 10 ms)

1228.8

1125 kB

418

4.18 seconds

2457.6

 2250 kB

209

2.09 seconds

 

Range: Depends on physical PC memory size
Default: 4000000

 

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Related Topics

Bit Error Rate Measurement