HSDPA Block Error Ratio Measurement Description

How is an HSDPA Block Error Ratio Measurement Made?

The HSDPA block error ratio (BLER) measurement can only be performed on a Radio Bearer Test Mode connection with a Channel Type of 12.2k RMC + HSDPA or 12.2k RMC + HSPA. To perform the HSDPA BLER measurement, the test set sends blocks of data to the UE on the downlink HS-PDSCH(s). The data sent on the downlink HS-PDSCH(s) is determined by the HS-DSCH Data Pattern setting (or FDD Test "HS-DSCH Data Pattern" in FDD Test Operating Mode ). The test set then monitors the positive acknowledgments (ACKs) and negative acknowledgments (NACKs) sent by the UE on the uplink HS-DPCCH.

The UE is required to respond to every block of data directed to it with either an ACK or NACK. If it does not respond to a block in its assigned TTI, the test set logs the event as a statistical DTX (statDTX). Also, if the UE responds to a block with data other than all 1s (ACK) or all 0s (NACK), the TTI is treated as a statDTX. StatDTXs are considered block errors, and are included in the BLER calculation. You can specify how the test set responds to statDTXs using the statDTX Reception Behavior setting.

In addition to ACK/NACK information, the uplink HS-DPCCH also carries channel quality indicator (CQI) information. The test set analyzes the CQI values sent by the UE and reports the Median CQI .

Dual Cell HSDPA Considerations

When DC-HSDPA is active, there are three sets of the HSDPA block error ratio results: One for the serving cell, one for the secondary serving cell and one for the combined serving cells.

FDD Test Mode Considerations

In FDD Test operating mode the test set does not provide radio bearer setup control of the UE. You must configure the UE to synchronize to the test set, demodulate the downlink HS-SCCH and HS-PDSCH channels and generate the appropriate uplink HS-DPCCH (see Synchronizing the UE to the Test Set's Downlink to Make Measurements ).

Once the UE begins transmitting its HS-DPCCH, the test set requires a finite amount of time to acquire and decode the UE's signal. If you initiate the HSDPA BLER measurement while the test set is still acquiring the UE's signal, the measurement will report statDTXs until it finishes its acquisition and begins demodulating the HS-DPCCH. To avoid an incorrect HBLER result, it is recommended that you wait approximately 2 seconds after the UE begins transmission of its HS-DPCCH before initiating the HBLER measurement (the amount of time required varies depending upon your test configuration).

HSDPA Block Error Ratio Measurement Parameters

• Number of blocks to test

  Sets the number of blocks to test during the measurement. See Blocks to Test Specified Per Serving Cell for more information about setting the number of blocks to test with active DC-HSDPA connections.

  Note, the time for the measurement to complete increases linearly with the Number of blocks to test . The test time (in seconds) is determined by:

  

  (It takes six sub-frames (0.012 s) for a block sent to the UE by a HARQ process to be acknowledged at the test set).

  When DC-HSDPA is configured (the Current Secondary Serving Cell Status is Configured-Active or Configured-Inactive) , and the Blocks to Test Specified Per Serving Cell is set to On , then this setting is not used, and the actual number of blocks to test for the measurement is determined by the DC-HSDPA Serving Cell Blocks to Test and DC-HSDPA Secondary Serving Cell Blocks to Test .

  GPIB Command: SETup:HBLerror:COUNt

• Blocks to Test Specified Per Serving Cell

  This setting is only applicable when DC-HSDPA is configured. It allows you to specify the number of blocks to be tested for each independent serving cell or for the combination of both serving cells.

  • If it is set to On , then the number of blocks to test for the serving cell is determined by DC-HSDPA Serving Cell Blocks to Test and the number of blocks to test for the secondary serving cell is determined by DC-HSDPA Secondary Serving Cell Blocks to Test .
  • If it is set to Off , then the number of blocks to test for each serving cell is not predicted, but the total number of blocks to test for the serving cell and the secondary serving cell is determined by Number of blocks to test .

  GPIB Command: SETup:HBLerror:COUNt:DCHSdpa[:STATe]

• DC-HSDPA Serving Cell Blocks to Test

  Sets the number of blocks to test during the measurement of the DC-HSDPA serving cell.

  GPIB Command: SETup:HBLerror:COUNt:DCHSdpa:SERVing

• DC-HSDPA Secondary Serving Cell Blocks to Test

  Sets the number of blocks to test during the measurement of the DC-HSDPA secondary serving cell.

  GPIB Command: SETup:HBLerror:COUNt:DCHSdpa:SECondary

• Trigger Arm: see Trigger Arm (Single or Continuous) Description .
• Measurement Timeout

  See Measurement Timeouts . If you set Measurement Timeout to On , ensure that the Measurement Timeout value is greater than the time the measurement needs to measure the desired Number of blocks to test .

The trigger source for this measurement is always protocol-based (see Trigger Source Description ).

HSDPA Block Error Ratio Measurement Results

• Block Error Ratio

  3GPP TS 34.121-1 F.6.3.2 defines the HSDPA block error ratio as:

  

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• Information Bit Throughput (kbps)

  This result reports the data throughput of the HSDPA connection. 3GPP TS 34.121 F.6.3.1 defines Information Bit Throughput R as "the sum (in kilobits) of the information bit payloads (excluding the 24-bit HS-DSCH CRC) successfully received during the test interval, divided by the duration of the test interval (in seconds)."

  Each time the test set receives an ACK from the UE, it increments a counter called "totalBits" by the size of the data block (in bits) that was positively acknowledged. Each time the test set transmits a data block on the HS-PDSCHs, it increments a counter called "blocksTransferred" (a transmission of a new block of data or retransmission of an old block of data both count as a block transmission). Each time the test set does not transmit a block in a TTI it increments a counter called regDTX.

  Throughput (in kbps) is then calculated as follows:

  

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection. However, when Blocks to Test Specified Per Serving Cell is On , the Information Bit Throughput for the combined dual cell is not available. This is because the blocks to test for each serving cell are configured independetly and the transmit time for each serving cell is not equal. Therefore, the overall time to complete the transmission of the total blocks in the dual cell cannot be calculated exactly.

• ACKs

  Number of positive acknowledgments received.

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• NACKs

  Number of negative acknowledgments received.

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• statDTXs

  Number of statistical DTXs received .

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• Blocks Tested

  Blocks tested is the number of blocks that were tested in determining the Block Error Ratio , Information Bit Throughput , ACKs , NACKs , statDTXs and Median CQI .

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• Median CQI

  The test set monitors the CQI values reported by the UE, then:

  1. Generates a CQI frequency distribution (number of occurrences of each CQI value)
  2. Generates a cumulative CQI frequency distribution (total number of occurrences at or below each CQI value)
  3. Determines the median value of the cumulative CQI frequency distribution (determines which CQI value is above the (n-1)/2 occurrence point, where n is the total number of CQI occurrences).

  This value is the Median CQI , as specified by 3GPP TS 34.121 9.3.1.4.2 step 4.

  For example:
  CQI frequency distribution (frequency/CQI): 1/10, 3/11, 5/12, 4/13, 2/14
  Cumulative CQI frequency distribution (cumulative freq/CQI): 1/10, 4/11, 9/12, 13/13, 15/14
  The Median CQI value occurs at (15-1)/2 = 7 occurrences, which lies between a CQI value of 11 and 12. The Median CQI value in this example is thus 12.

  Results are provided for the serving cell, secondary serving cell and combined dual cell with an active DC-HSDPA connection.

• Integrity Indicator

HSDPA Block Error Ratio Measurement Input Signal Requirements

• The expected power into the test set must be set in order to maintain the link with the UE. This is done using the UE Target Power setting or by using manual receiver power control and specifying the expected power level. See Receiver Control .

• Frequency: 800 to 1000 MHz, 1700 to 1990 MHz
• Input level: -61 dBm to +28 dBm

Related Topics

Manual Operation: How Do I Make an HSDPA Block Error Ratio Measurement?

Programming an HSDPA Block Error Ratio Measurement

HSDPA Block Error Ratio Troubleshooting

HSDPA Counters

DC-HSDPA Counters

Block Error Ratio (BLER) Measurement Description

What 3GPP W-CDMA/HSPA Conformance Tests Are Supported?