FDD Test Operating Mode

FDD Test Operating Mode

Last updated: April 27, 2013

FDD Test Overview

In FDD Test (frequency division duplex) Operating Mode , the test set does not send any signalling information on the downlink. Any changes to the UE configuration, such as channel, loopback type, or dedicated physical channel (DPCH) scrambling code, must be accomplished by directly sending commands to the UE from a system controller (usually a personal computer) through a proprietary digital interface.

Upon entry into test mode, the test set begins continuously transmitting a downlink signal which consists of a dedicated physical channel (DPCH) configured as the specified symmetrical reference measurement channel (see Symmetrical RMCs ) and several overhead channels required to allow the UE to synchronize to the test set and decode transmitted data (see Downlink and Uplink Channels Overview ). When HSDPA is active ( for lab applications and feature-licensed test applications only ), the test set also transmits up to 5 HS-PDSCHs (as determined by the FDD Test "FRC Type" setting) and up to 4 HS-SCCHs (see HSDPA in FDD Test Operating Mode ).

The UE must synchronize to the transmitted downlink channels and transmit the proper corresponding uplink signal(s). The UE's performance can then be measured using the suite of measurements available in the test set. To emulate interference from other cells or users, two noise sources (OCNS and AWGN) can be added as desired.

The following example selects FDD Test operating mode via GPIB:

 
OUTPUT 714;"CALL:OPERating:MODE FDDT"

Synchronizing the UE to the Test Set's Downlink to Make Measurements

The following test set controls must match your UE configuration to allow it to synchronize to the test set's downlink signal and transmit an uplink signal that the test set can receive and measure:

Additional FDD Test Mode Settings

FDD Test Operating Considerations

The test set can perform loopback bit error ratio (BER) measurements if the UE provides a loopback mode that conforms to 3GPP TS 34.109, section 5.3.2.6.2, Loopback of RLC SDUs . Additionally, the uplink DPDCH transport format must be set so both the dedicated traffic channel (DTCH) and dedicated control channel (DCCH) are present (however, the test set will ignore the contents of the DCCH so the actual content of this channel is not relevant).

When the test set and the UE are synchronized, the UE uplink frame starts 1024 chips after the receiving the corresponding downlink frame. Measurements that require synchronization will not trigger correctly (or at all) if this timing relationship does not exist.

In FDD Test operating mode, the test set does not negotiate with the UE to set up a call, or provide any other form of interactive control of the UE (other than uplink closed loop power control, see UL CL Power Ctrl Parameters ). You can select the transport format indication (TFCI) pattern sent to the UE on the downlink, but the test set does not assume or verify that the UE responded. The test set ignores transport format combination indicator (TFCI) and transmit power control (TPC) bits sent on the uplink.

HSDPA in FDD Test Operating Mode

This section is only applicable to the lab application or feature-licensed test application.

HSDPA Activation in FDD Test

In FDD Test operating mode, HSDPA is active when Channel Type is set to 12.2k RMC + HSDPA .

HSDPA Operation in FDD Test

When HSDPA is active, in addition to the 12.2k RMC and common channels, the test set transmits up to 5 HS-PDSCHs (as determined by the FDD Test "FRC Type" or FDDT "User Defined Number of Active HS-PDSCHs" settings) and up to 4 HS-SCCHs. The test set also generates a six-channel OCNS as specified by 3GPP TS 34.121 sE.5.2 (codes 122 - 127, spreading factor 128), rather than the OCNS defined in sE.3.6 (see OCNS in HSDPA/HSPA ).

When HSDPA is active, the test set expects the UE to transmit a 12.2k RMC as well as an HS-DPCCH that contains ACK/NACK information corresponding to the downlink HS-PDSCH data. The HSDPA Information window displays counters to help you monitor the HSDPA connection status. Note, the test set expects an uplink DPCCH to be present when an uplink HS-DPCCH is transmitted (otherwise the HS-DPCCH can not be decoded as there are no pilot bits in the HS-DPCCH).

In FDD Test operating mode, the test set does not signal the Ack-Nack Repetition Factor to the UE, you must set the value manually in the UE. To ensure valid HSDPA BLER results, you must ensure that the minimum inter-TTI of the active HSDPA channel is greater than or equal to 2 ms * Ack-Nack Repetition Factor (so that there is sufficient space on the uplink for the ACK/NACK repeats to be transmitted). See Ack-Nack Repetition Factor for more information about this requirement.

In FDD Test operating mode, the test set does not signal the CQI Feedback Cycle (k) or CQI Repetition Factor to the UE, you must set the values manually in the UE. To ensure a valid Median CQI result, you must ensure that CQI Feedback Cycle (k) is greater than or equal to CQI Repetition Factor * 2ms (so that there are no collisions between new and repeated CQI information). See CQI Transmission Settings for more information about this requirement.

The following diagram illustrates the HSDPA FDD test mode configuration in the test set, as well as the expected channels from the UE:

To test HSDPA UEs in FDD test mode, you must synchronize the UE and test set as described in Synchronizing the UE to the Test Set's Downlink to Make Measurements .

Additionally, you must consider the following:

HSPA in FDD Test Operating Mode

This section is only applicable to the lab application or feature-licensed test application.

HSPA Activation in FDD Test

In FDD Test operating mode, HSPA is active when Channel Type is set to 12.2k RMC + HSPA .

HSPA Operation in FDD Test

When HSPA is active, the test set operates a fully functional Layer1 plus MAC-e solution, in that E-DCH blocks are decoded according to the E-TFCI and the appropriate ack or nack is sent on the E-HICH. The test set discards any blocks received on the E-DCH after transmitting the ack or nack. This means that the UE may use any value it likes for the DDI, N and TSN fields in the MAC-e/es PDU. There is no signaling on the control plane above MACe/es.

While on an HSPA channel in FDD Test Mode, the HSDPA downlink operates much as it does for an HSDPA-only channel type. The primary difference is that while on an HSPA channel the HS-DSCH transmits RLC PDUs that contain valid RLC UM headers. This is in contrast to HSDPA-only FDD test mode where there are no RLC headers sent on the HS-DSCH (PRBS data is sent instead). The headers are necessary so that the UE can loop back the downlink data received on the HS-DSCH back onto the uplink E-DCH. The loopback point in HSPA FDD test mode is expected to be immediately above the UE's RLC layer (which is the same place as for active cell). This means the RLC layer must deliver complete blocks to the loopback entity for there to be data on the E-DCH. The UE's RLC UM entity can only deliver blocks up to its loopback entity if it is receiving consistent header data (not PRBS data) that allows it to recreate complete SDUs. While operating on an HSPA channel type in FDD test mode the test set therefore transmits valid RLC UM headers. The RLC PDU size is 336 bits when an HSDPA FRC is configured (this matches the specification for FRCs in 3GPP TS 34.121) or 112 bits when an HSDPA user defined configuration is used. The downlink RLC SDU size is set to 2936 bits (just like in active cell operating mode). As many RLC PDUs are packed in a single MAC-hs PDU as will fit, subject to the same limits as described in HSPA Radio Bearer Test Mode . The same MAC-hs header format as described in MAC-hs Header above is used with the exception that the N field is set to the actual number of RLC PDUs packed in the MAC-hs PDU.

To test HSPA UEs in FDD test mode, you must synchronize the UE and test set as described in Synchronizing the UE to the Test Set's Downlink to Make Measurements .

Additionally, you must consider the following:

Related Topics

Cell Power and AWGN Power

CALL:FDDTest

Receiver Control

Active Cell Operating Mode