User`s guide

Agilent PXT Wireless Communications Test Set
User’s Guide
227
Monitor CPU usage while running multiple TCP streams/threads to ensure it does not
exceed 90 %.
Bi-directional TCP – Low rate observed
Running bi-directional Iperf TCP streams can show low bitrates either at the DL or UL streams. Iperf ramps the
bitrate up to maximum on both directions, and depending on which side saturates the bandwidth, the other
side is starved of bandwidth for required TCP ACKs.
The work around is to attempt to cap the bitrate in both directions, allowing enough bandwidth in both the DL
and UL for ACK responses. Using Iperf makes it difficult for this as there is no capping of the bitrate in TCP,
similarly with TCP TDD links Iperf usually requires multiple processes which makes it more difficult to restrict
the bitrate of the TCP streams to allow for the other direction’s TCP ACKs.
UDP is best used for bi-directional,
or UDP one direction - TCP the other direction works good.
E2E data throughput testing for long durations – UE disconnects around 3
hours with DL Subframe#5 set to MAXTh
When running long term soak tests of E2E data throughput tests, please note that when using PHY DL
Subframe#5 = MAXTh (Max throughput) setting, the PXT does not send system information reports to the UE,
as all sub frames are being used for E2E traffic data. The UE may disconnect after 3 hours of operation due to
lack of System Information report. For best results in long term soak tests of E2E data throughput use either DL
Subframe#5 = Normal or RCT for stable operation.
Connection Status monitor also does not function when DL Subframe#5 = MAXTh mode is enabled. Typical
behaviour with MAXTh setting is after 3 hours of operation is the E2E link stops as the UE device has
disconnected, and due to the Connection Status monitor not functioning in this mode, the E2E stats simply
show 100% NAKs.