Agilent Measurement Journal - Issue 3 - 2007 - (Page 30)

Sketching potential QoE problems QoE is paramount. Consider the case of a subscriber trying to change the TV channel. First, they would press the “channel” button on the remote control. Behind the scenes, IGMP leave and join commands are sent from the set-top box to the residential gateway and on to the delivery network. Depending on trafﬁc load and the location of the multicast video on the network, there is a variable delay between when the button is pressed and the appearance of the new channel. If the delay is too long, the subscriber might press the button again, thinking it did not work — and suddenly the channel will change twice. The main reason for this poor QoE is nonconstant channel “zapping.” A similarly negative experience may result when a service provider changes the priority of services in a broadband connection after adding high-bandwidth IPTV services. A gaming user, who was accustomed to a fast, predictable network response, may experience a slow and irregular response because the service no longer has top priority (though this could potentially be corrected with a conﬁguration change). Monitoring and diagnosing problems Tools such as the Agilent J6900A triple play analyzer aid in the successful monitoring, diagnosing and troubleshooting of such problems (Figure 1). For network equipment manufacturers and communication service providers, the triple play analyzer can be used as a dispatched tool or as part of a system-wide monitoring and troubleshooting solution. To effectively monitor and diagnose the root problem within a network, the analyzer starts its measurements with a global view of the trafﬁc, automatically separating and classifying data into TCP/IP trafﬁc, MPEG2-TS streams (IPTV or VoD) and real-time transport protocol (RTP) streams (VoIP or IPTV). A breakdown of the different types of trafﬁc is displayed, helping the user quickly identify which ones require further analysis. To obtain further details on the performance of speciﬁc services in the network, the analyzer can drill down to speciﬁc voice, data or video streams, identifying the causes of media and signaling impairments in the network. The RTP view provides a detailed analysis of the performance of voice and video streams in the network. MPEG2 transport streams can be encapsulated over UDP or UDP and RTP. The analyzer automatically identiﬁes RTP steams and performs detailed analysis of parameters such as packet and byte count, packet loss and delay, throughput and percentage of bandwidth. Media Delivery Index Within the communications industry, MDI is gaining acceptance for media quality testing over an IP video delivery infrastructure. MDI is an industry standard deﬁned in RFC 4445 and endorsed by the IP Video Quality Alliance. MDI is composed of two parts: the delay factor (DF) and the media loss rate (MLR). These are based on jitter and loss, two concepts that translate directly into networking terms. MDI correlates network impairments with video quality, which is vital for isolating problems and determining their root causes. Figure 1. Agilent J6900A triple play analyzer 30 Agilent Measurement Journal

Table of Contents Feed for the Digital Edition of Agilent Measurement Journal - Issue 3 - 2007

Applying Ingenuity to the Measurement of Emerging Technologies Contents Emerging Innovations Department Delivering Bigger Benefits by Optimizing Customer Workflows Measuring Material Properties at the Nanoscale Utilizing In Situ Atomic Force Microscopy in Life Science, Pharmaceutical and other Bio-Related Applications WiMAX™: Plotting a New Path to Global Mobility Addressing the Triple Complexity of Triple-Play Networks What Next for Mobile Telephony? Exploring the Inner Workings of Tire-Pressure Monitoring Systems Developing, Assessing and Applying a High-Resolution Thin-Film Magnetic Probe Making Accurate Settling-Time Measurements Using a Vector Network Analyzer Applying Metabolomics Methods to the Study of Bacterial Leaf Blight in Rice Plants Measuring Stream Dynamics with Fiber Optics survey

Agilent Measurement Journal - Issue 3 - 2007

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