Application Note
Advanced IPTV Testing Using the JDSU SmartClass™ TPS
RTP Testing Using Loss Distance/Loss Period Measurements
Test Challenge
To ensure reliable picture quality, second-generation
Internet Protocol television (IPTV) ecosystems typically
provide forward error correction (FEC) or error
recovery mechanisms that include retrans-mission of
lost packets. These networks promise excellent quality
of experience (QoE) to users who assume IPTV to be an
error-free service.
Two loss events
The JDSU SmartClass TPS Tester
is the ideal tool for technicians
who install, troubleshoot, and
maintain Triple-Play services
Addressing the Challenge with SmartClass TPS
To help address packet loss and maintain tolerable IPTV packet loss thresholds, the SmartClass TPS tester
deploys a key performance indicator, measuring the shape of a Real-Time Protocol (RTP) packet loss event. In
the event, the loss period defines the length of a single loss event and loss distance defines packet increments
between two loss periods (events). New retransmission error recovery mechanisms can tolerate very aggressive
loss period limits of up to 30 consecutive lost packets, but the distance between the loss events should be at least
three times the length of the error: a loss period limit of 30 would require a loss distance limit of 90 to 120 packets.
The example below shows two loss events, Pkt2 and Pkt5 through Pkt7. The first event is a loss period of 1 packet,
and the second event is a loss period is 3 packets. The distance between the two events is loss distance of 3 packets.
Offering RTP analysis makes the SmartClass
TPS capable of truly measuring network
quality of service (QoS) and QoE.
Conclusion
Traditional QoS parameters, such as packet loss, diverge from QoE; this means that the network experiences a
decrease in quality due to packet loss while the user still views excellent video. The amount of tolerable packet
loss before impacting consumer QoE is yet to be determined (not standardized) for this dynamic IPTV industry
environment. Introducing key performance indicators, such
as measuring the shape of an RTP packet loss event, further
ensures QoE. In addition to QoS test capabilities, the JDSU
SmartClass TPS offers many QoE test functions, including
RTP packet loss analysis that provides industry-leading depth
of analysis, including the previously described distance-loss
period—parameters that help qualify a packet loss event
by setting a threshold for maximum period and minimum
distance and determine if the lost packets are crucial to IPTV
performance.
Product specications and descriptions in this document subject to change without notice. © 2011 JDS Uniphase Corporation 30162720 001 0511 SMCLASSTPSIPTV.AN.ACC.TM.AE May 2011
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Pkt 1 Pkt 2 Pkt 3 Pkt 4 Pkt 5 Pkt 6 Pkt 7 Pkt 8 Pkt 9
Loss Distance of 3
{
{
Loss Period of 3
{
Loss Period of 1
SmartClass TPS Packet Loss screen