Parameter Interactions (W-CDMA(3GPP)/HSPA)
When using W-CDMA Code Division Multiple Access: One of several digital wireless transmission methods in which signals are encoded using a specific pseudo-random sequence, or code, to define a communication channel. A receiver, knowing the code, can use it to decode the received signal in the presence of other signals in the channel. This is one of several "spread spectrum" techniques, which allows multiple users to share the same radio frequency spectrum by assigning each active user an unique code. CDMA offers improved spectral efficiency over analog transmission in that it allows for greater frequency reuse. Other characteristics of CDMA systems reduce dropped calls, increase battery life and offer more secure transmission. See also IS-95. (3GPP)/HSPA demodulation, changing one parameter may necessitate changes in other parameters to achieve the desired measurement. For example,
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limits .
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Minimum may limit the (this may occur when playing back a recording or analyzing data from the stream interface).
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and are limited by the .
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enables these features: the configuration options and parameters.
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Changing link changes the valid limits for many parameters
The following table shows how measurement parameters affect W-CDMA (3GPP)/HSPA demodulation.
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W-CDMA (3GPP)/HSPA Demodulation Parameters |
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Time Sequence |
Parameters Involved |
Effect |
Result |
Notes |
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Signal setup |
Range: Trigger Frequency/span Input Time Corrections |
Sets up basic signal parameters required for digital demodulation. |
Raw data. |
Any changes made in the signal setup parameters later in the time sequence require that a new measurement be performed. |
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Demodulation |
Setup parameters: Chip Rate Direction-Link Scramble-Code Scramble-Code-Offse Scramble-Code-Type Sync-Type Test Model Defined Channels Enable HSPA Active Channel Threshold Include IQ Offset Suppress SCH for channel meas Include SCH in composite meas Bypass RRC Meas Filter |
Determines the type of demodulation performed on the input time data. |
Demodulated, symbol-locked data in the default display format. |
Result length determines the amount of data that is demodulated. |
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Post-demodulation |
Meas Offset Meas Interval Channel Code Channel Spread Code Length CDP-Layer Spread Code Length Bit Format tDPCH |
Specifies channel and determines how much data is used for the trace data results. |
Demodulated data in the default display format. |
Changes may be made in the display parameters without acquiring a new measurement |
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Display Formatting |
Trace data Trace format X and Y Scale Marker IQ Normalize |
Formats the data for display. |
Formatted, demodulated data. |
Changes may be made in the display parameters without acquiring a new measurement |
The following topics may help optimize your measurements and explain the reasons for changes made automatically by the VSA.
See Also
