The W-CDMA specifications (3GPP TS 34.109) define a Radio Bearer Test Mode which includes a suite of uplink (UL) and downlink (DL) reference measurement channels (RMCs) to use for UE transmitter and receiver conformance test. See Radio Bearer Test Mode, TC, and Reference Measurement Channels .
The test set supports the following RMCs:
The symmetrical RMCs are typically used for transmitter testing and for receiver testing using BER (via loopback type 1) or BLER (using loopback type 2).
The symmetrical RMCs always use Transparent Mode (TM) RLC entities on the DTCH. The UE must send the Close UE Test Loop Complete message to the test set before it will start transmitting data on the downlink DTCH.
33k No Coding RMC
This Keysight proprietary RMC does not use convolutional coding on the downlink data, to allow for raw BER testing (see Loopback Bit Error Ratio (BER) Measurement Description ).
The asymmetrical RMCs allow high data rate receiver testing in UEs that don't support rates above 64 kbps in the uplink. The asymmetrical RMCs use Acknowledged Mode (AM) RLC entities on the DTCH. When the asymmetrical RMCs are used, the BLER measurement calculates the block error ratio by counting the number of retransmission requests that the UE makes on its DTCH.
The 12.2k uplink channel used in the asymmetrical RMCs is not the same as the 12.2k uplink channel used by the symmetrical RMCs, as that channel has a DTCH block size that is not a multiple of 8 bits (to use AM RLC entities, the data block size must be a multiple of 8 bits). Asymmetrical RMCs use the 12.2k Aux-MC which is essentially a regular 12.2k RMC but with a slightly different DTCH block size that is a multiple of 8 bits.
You can specify whether the loopback is closed for asymmetrical RMCs using the Asymmetric RMC Loopback Messaging parameter.
Asymmetrical RMCs are not available in FDD test operating mode.
Use the
Channel Type
setting to specify which RMC to use when establishing an
RB Test Mode
connection with the UE.
You can configure the following characteristics of the RMC channels when operating in
RB Test Mode
. These parameters can only be changed when the call status is idle.
See HSDPA RB Test Mode Settings and HSUPA RB Test Mode Setup for information on other settings available for configuring the HSDPA and HSPA Radio Bearer Test Mode connections ( lab application or feature-licensed test application only ).
In the lab application only, this setting controls whether the RB Test Mode service will configure the UE into a CELL_FACH or CELL_DCH state. The CELL_DCH state is used for all 3GPP TS 34.121 RF tests except Receiver Spurious Emissions, which requires the use of CELL_FACH. See Radio Bearer Test Mode Origination to CELL_DCH - CS Domain (Non-HSPA or HSDPA) and Radio Bearer Test Mode Origination to CELL_FACH .
GPIB command: CALL:SERVice:RBTest:RRC:STATe .
To query the current RRC State, see RRC State .
This setting controls whether the uplink transport channel carrying the DTCH has a Cyclic Redundancy Check (CRC) field or whether the bits that would normally be used for this CRC field are used to carry data instead. If this parameter is set to
Present
, then the test set assumes that the bits in the CRC field are actual CRC bits for the uplink transport block. If the parameter is set to
Used for Data
, then the test set assumes that the bits in the CRC field are just data bits. In other words, the UE is NOT sending uplink CRC bits, but instead is sending more data bits in their place (such as looped back downlink CRC bits).
Uplink DTCH RMC CRC Presence
must be set to
Present
when performing the loopback BER measurement (see
Loopback Bit Error Ratio (BER) Measurement Description
) so that the measurement can detect and report any uplink CRC errors that occur while the measurement is running (any uplink errors that occur during receiver testing invalidate the results, and must be considered).
Uplink DTCH RMC CRC Presence
must be set to
Used for Data
when performing the loopback block error ratio measurement for
Symmetrical RMCs
(see
Block Error Ratio (BLER) Measurement Description
). This disables the uplink CRC, to allow room for the UE to loop back the downlink CRC for each block (there are an equal number of bits in the uplink and downlink transport blocks, if the UE were to transmit an uplink CRC, it would not be able to loop back the downlink CRC).
When on an HSDPA RB test mode connection (see
HSDPA RMCs
), the
Uplink DTCH RMC CRC Presence
setting only controls the presence of the CRC on the RMC portion of the channel. It is not possible to control the presence of the CRC on the FRC.
GPIB command: CALL:SERVice:RBTest:DTCHannel:CRC[:PRESence] .
This setting can be changed using a Radio Bearer Reconfiguration .
3GPP TS 34.109 section 5.3.2.8 specifies that when UE test loop mode 1 or 2 is active, if DCCH dummy mode is enabled and there is no DCCH data to be sent, then the UE shall set all bits in the uplink DCH transport block associated with a DCCH to 1. Thus, if the Uplink Dummy DCCH Data parameter in the test set is set to On, the test set discards any received DCH transport blocks associated with a DCCH having its bits set to 1.
GPIB command: CALL:UPLink:DCCHannel:DDATa .
This setting can be changed using a Radio Bearer Reconfiguration .
This setting controls which loopback mode the Test control (TC) protocol layer instructs the UE to go into. This is signaled to the UE in the Close UE Test Loop message. In
Type 1
loopback mode, the loopback point is just above the traffic plane RLC entities (see 3GPP TS 34.109, 5.3.2.6). In
Type 2
loopback mode, the loopback point is just above the layer 1 transport channels (see 3GPP TS 34.109, 5.3.2.7).
Typically, you should set
MS Loopback Type
to
Type 1
when performing the loopback bit error ratio measurement (see
Loopback Bit Error Ratio (BER) Measurement Description
).
You must set
MS Loopback Type
to
Type 2
when performing the loopback block error ratio measurement for
Symmetrical RMCs
(see
Block Error Ratio (BLER) Measurement Description
).
The
UE Loopback Type
setting does not apply when loopback is closed for asymmetrical RMCs. Asymmetrical RMCs are always closed with a loopback type of 1.
GPIB command: CALL:MS:LOOPback:TYPE .
This setting can be changed using a Radio Bearer Reconfiguration .
The
Asymmetric RMC Loopback Messaging
parameter allows you to specify whether Open/Close UE Test Loop messages are used for asymmetrical RMCs.
3GPP TS 34.108 and 34.121 state that even for an asymmetrical RMC, the call setup shall include the Close UE Test Loop message (and the call release shall include the Open UE Test Loop message). The Close UE Test Loop message must contain a loopback SDU size of zero to prevent any data from actually being looped back (so that the uplink is left free for the RLC Acks and Nacks). The loopback type is always 1 for asymmetrical RMCs (as the SDU size is not controllable for loopback type 2). Thus, the UE Loopback Type setting does not apply to the asymmetrical RMCs.
This parameter does not affect the call setup/release procedures for symmetrical RMCs.
Asymmetric RMC Loopback Messaging
is set to
Close/Open
, the test set sends the UE a Close UE Test Loop message with the loopback type set to 1 and the SDU size set to zero bits during the asymmetrical RMC call setup.
Asymmetric RMC Loopback Messaging
is set to
None
, the test set does not send the UE a Close UE Test Loop message or an Open UE Test Loop message during asymmetrical RMC call setup/release. This setting provides for faster call setup/release procedures. Note, if a Close UE Test Loop message is not sent to the UE when establishing the asymmetrical RMC, you can not send an Open UE Test Loop message as part of a Physical Channel Reconfiguration (see
RB Test Mode PCR Loopback Messaging State
).GPIB command: CALL:SERVice:RBTest:ARMC:LMESsaging
This section is only applicable to the lab application or feature-licensed test application.
HSDPA Radio Bearer Test Mode uses an HSDPA RMC that combines a 12.2 kbps symmetrical RMC with an HSDPA channel that you can configure as a Fixed Reference Channel (FRC) or to a user-defined configuration of your choice (as determined by the
RB Test HS-DSCH Configuration Type
setting). Once you've set
Channel Type
to
12.2k RMC + HSDPA
, you must then specify the
HS-DSCH Configuration Type
, then either set
FRC Type
or the
User Defined Configuration of the HS-DSCH
settings as desired. See
HSDPA Parameters
for information on other settings available for configuring the HSDPA Radio Bearer Test Mode connection.
This section is only applicable to the lab application or feature-licensed test application.
HSPA RB Test Mode combines a 12.2 kbps symmetrical RMC with an HSDPA channel and an HSUPA channel. The HSDPA channel can be configured as an FRC or to a user-defined configuration as explained in HSDPA Radio Bearer Test Mode above. The HSUPA channel is configured as per 3GPP TS 34.121 sC.11, and can be further configured using the HSUPA Parameters .
While on an HSPA RB Test Mode connection the UE is instructed to loop the downlink RMC DPCH onto the uplink RMC DPCH and the downlink HSDPA channel onto the uplink HSUPA channel (the downlink HS-DSCH is used as the data source for the uplink E-DCH). As HSDPA and HSUPA do not have symmetrical data rates it is not possible to precisely match the downlink data rate to the uplink data rate (as you can for a regular RMC). It is desirous to ensure that the UE always has enough data in its transmission buffers to let it fully utilize its current serving grant (so that the E-AGCH and E-RGCH control the output level of the UE). The test set supports two downlink configurations to ensure sufficient traffic on the uplink:
FRC
and
FRC Type
=
H-Set 1 QPSK
, the downlink RLC SDU size is 2936 bits and the downlink RLC PDU size is 336 bits. The test set packs a continuous stream of RLC SDUs into the RLC PDUs (thus a PDU may contain the end of one SDU and the beginning of the next SDU). Each RLC PDU is then packed into a MAC-d PDU, and as many MAC-d PDUs are packed into the MAC-hs PDU as will fit (subject to the maximum limit of 70 PDUs as per 3GPP TS 35.321 s9.2.2). This configuration conforms strictly to 3GPP TS 34.108 and 34.121.
Regardless of the downlink configuration, the uplink RLC SDU size varies between 2936 and 35232 (based upon the
RB E-DPDCH Max Channel Codes (HSPA)
setting). The uplink RLC PDU size is 336 bits. Because HSPA RB Test Mode connections use loopback type I, it is possible for the UE to transmit more data on the E-DCH than it is receiving on the HS-DSCH by setting a large
E-DCH RLC SDU Size
(the UE simply repeats data if the uplink SDU is larger than the downlink SDU, see 3GPP TS 34.109 v6.3.0 s5.3.2.6.2). This feature of loopback type I allows the second downlink configuration described above to drive the uplink at sufficiently high rates.
This feature of loopback type I also allows you to achieve 2 Mbps in the uplink with less than 2 Mbps in the downlink (H-Set 1 QPSK downlink data rate = 534 kbps). For example, to achieve 2 Mbps in the uplink with the downlink configured to H-Set 1 QPSK (534 kbps), set
E-DCH RLC SDU Size
to at least 4 x 2936 bits = 11744 bits. Note that you must also set
RB Test Mode E-DPDCH Max Channel Codes
=
2SF2
, grant the UE a large enough serving grant to allow this data rate, and ensure that the UE's transmit power is low enough that the HSUPA channels do not get scaled down.
The
Channel Type
setting allows you to specify which RMC to use while operating in
Radio Bearer Test Mode
.
Channel Type
can be set to:
The asymmetrical RMCs are not available in
FDD Test Operating Mode
. If
Channel Type
is set to an asymmetrical RMC and you move to
FDD Test Operating Mode
,
Channel Type
is changed to
12.2k RMC
.
This setting can not be changed while on a call. To move between channel types while on a connection, see Handovers .
GPIB command: CALL:SERVice:RBTest:RAB
How Do I Configure the Radio Bearer Test Mode?
How Do I Change Call Parameters?
Downlink Channel Codes and Levels