Downlink

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

 

1. Downlink Antenna Carrier Setup

Operating State allows the downlink 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 Downlink Operating State tool bar icon ().

 

IQ Sample Width specifies the width of the sample that will be output to the RE.

Range: 8 – 20
Default:
16

The IQ sample width and the CPRI line bit rate are used to define the number of antenna carriers that can be transmitted at one time. The antenna carrier limitations are listed in Downlink Antenna Carrier Limitations.

Downlink Antenna Carrier Limitations

 

The number of antenna carriers that you can transmit at the same time in the Downlink mode is based on:

    Number of Antenna Carriers Allowed at the Same Time in Download Mode

IQ Sample Width

CPRI Line Bit Rate

614.4 MB/s

1228.8 MB/s

2457.6 MB/s

8

7

15

24

9

6

13

24

10

6

12

24

11

5

10

21

12

5

10

20

13

4

9

18

14

4

8

17

15

4

8

16

16

3

7

15

17

3

7

14

18

3

6

13

19

3

6

12

20

3

6

12

 

 

Frame Packing Option sets the method for mapping each antenna carrier output sample into the CPRI frame.

Selections: Packed, Flexible
Default:
Packed

In each case, all antenna carrier output samples that are selected in the Enable column are mapped into the frame as a complete block without overlapping the next sample. Bits in the frame that are not used are assigned a "0" and treated as reserved bits ("r").

Examples

Antenna Carrier Samples Packing Option Examples

 

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Apply Normalization allows the waveforms of all enabled antenna carriers to be normalized to values between 1 and 1.

Selections: No, Yes
Default:
No

The maximum absolute sample value of all waveforms is normalized to be 1. All other sample values are normalized using the equation:

Normalized Value = Sample Value / Maximum Absolute Sample Value

 

Number of Carriers Allowed is a read-only field that displays the number of antenna carriers that may be transmitted at one time.

The IQ sample width and the CPRI line bit rate defines the number of antenna carriers that can be transmitting at one time. The antenna carrier limitations are defined in Downlink Antenna Carrier Limitations.

Downlink Carrier Limitations

 

The number of carriers that you can transmit at the same time in the Downlink mode is based on:

 

    Number of Antenna Carriers Allowed at the Same Time in Download Mode

 

Output Sample Width

CPRI Line Bit Rate

614.4 MB/s

1228.8 MB/s

2457.6 MB/s

8

7

15

24

9

6

13

24

10

6

12

24

11

5

10

21

12

5

10

20

13

4

9

18

14

4

8

17

15

4

8

16

16

3

7

15

17

3

7

14

18

3

6

13

19

3

6

12

20

3

6

12

 

 

 

Number of Carriers Enabled is a read-only field that displays the number of antenna carriers that are currently selected in the Enable column.

If the number of carriers enabled exceeds the number of carriers allowed, an error message is displayed when the downlink operation is started.

 

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Individual Antenna Carrier Setup

AxC is a read-only column that lists the 24 possible antenna carriers.

The antenna carriers are numbered 0 to 23.

 

Enable is a column that allows you to select the antenna carriers that are packed into frames for transmission to the RE.

Click an empty checkbox to enable the antenna carrier. Click the checkbox of an enabled antenna carrier to disable it.

The number of carriers supported by the Downlink measurement at one time is limited by the IQ Sample Width value and the CPRI line bit rate and is displayed in Number of Carriers Allowed. The number of carriers that are enabled is listed in Number of Carriers Enabled.  If the number of carriers enabled exceeds the number of carriers allowed, an error message is displayed when the downlink operation is started.

 

Waveform File is a column that displays the waveform file associated to the antenna carrier.

This file is transmitted to the RE when the antenna carrier is enabled. Downlink can transmit the following file types:

Double-click the Waveform File cell for the desired antenna carrier to display the AxCN (where N is the antenna carrier number) dialog box. This dialog box allows you associate a waveform file with the antenna carrier.

AxCN Dialog Box

The AxCN dialog allows you to associate a waveform file with the antenna carrier.

The Waveform File Type allows you to select a WCDMA file created by the N7600A Signal Studio for 3GPP W-CDMA with HSDPA/HSUPA software application or a binary (BIN) file created by another software product that you may be using to create a waveform file.

Enter the waveform file's path and file name in the Waveform File box or use the Browse button to find the file using a browser.

When loading a waveform file for download, there are limitations to the size of waveform that can be used. These limitations are based on the line bit rate.

When you assign a waveform file to an antenna carrier, you may not be able to view the entire path or file name. Steps to view the complete path and file name

If the path is long and exceeds one line, the display may resemble the illustration below.

However, you can adjust the height of the row to show the entire path and file name. In the gray column to the left of the AxC column, Move you cursor to the horizontal line at the bottom of the row.

When you move the cursor so that it becomes a double-headed vertical arrow, click the horizontal line and drag in down slightly to increase the height of the row.

 

 

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W Address is a column that allows you to enter the word address location that the software uses to start mapping the antenna carrier output sample into the CPRI frame.

Range: 1 – 15

The starting address is defined by the word address along with the bit address. This column is applied only when the Frame Packing Option is set to Flexible.

 

B Address is a column that allows you to enter the bit address location that the software uses to start mapping the antenna carrier output sample into the CPRI frame.

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

 

The starting address is defined by the bit address along with the word address. This address must be an even number within the listed range. This column is applied only when the Frame Packing Option is set to Flexible.

 

Power Scaling (dB) is a column that allows you to reduce the waveform power of the antenna carrier by the attenuation value specified in decibels.

Range: Any value less than or equal to 0 dB
Default: 0 dB

The entire waveform is attenuated by value specified. This value is entered as a negative value.

 

Alignment is a column that allows you to select where to add zeros to the waveform sample if the input sample width is shorter than the width defined in IQ Sample Width.

Selections: Trailing Zeros, Leading Zeros
Default:
Trailing Zeros

Zeros are appended to the input sample until the width of its bits equals the output sample width.

Example

 

If the width of the input sample is 16 and the Output Sample Width = 20, four "0's" are appended to the input sample as shown below.

 

 

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