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IPTV network scenario


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IPTV network scenario

  1. 1. The task of building and operating an IPTV network is a project with many challenges. The IPTV network infrastructure is a thrilling combination of many different building blocks. It involves encoding a video signal at the head-end site and transporting it through a complex network environment to the end user, where the signal is decoded and brought up on the TV screen. During this process a lot of things may happen. The IPTV service provider must have a clear picture of the overall health of the complete network. A common set of monitoring parameters and points need to be defined in order to perform this task. Service Level Agreements and Quality levels must meet the promised expectations. Quality may be measured or quantified in different ways, such as QoS, QoP or QoE. But at the end of the day, it is your user that decides if your IPTV service lives up to his expectations. IPTV needs to gain the confidence of the consumer, and this requires that the overall quality is at a certain predefined level. QoS – Quality of Service – is an acronym used in IP networks to express techniques for achieving predictable packet forwarding for parameters such as percentage of dropped packets, variation in packet arrival time (jitter) and service restoration time. However, QoS does not take into account how the service is perceived by the end-user in terms of service quality. The network might be behaving perfectly within QoS parameters, but what is the customer’s real perception of the service, and how do you quantify it? QoS incorporating user-level perception may be defined as Quality of Perception (QoP). This measure not only looks at user satisfaction with multimedia clips, for example, but also the user’s ability to perceive, synthesize and analyze the information presented in the content of such presentations. But what really counts is the Quality of Experience (QoE) measure, defined as the level that customers perceive if the Service Provider is doing a good job delivering the service. Usually, the QoE of a customer is only known when he calls to make a complaint or if subscription revenue drops. An IPTV QoE measurement may consist of several components including equipment quality, human factors, environmental factors, and transport quality. Since IPTV is dynamic, QoE should be measured as “per unit time over time”. For example, if a customer subscribes to an IPTV service that delivers the Tour de France in High Definition and the QoE was very high for 1 hour of the transmission and poor for the last 1½ hour, what is the QoE for the customer? Most likely, quite poor. The same is true with a phone call that lasts 20 minutes: if the last minute’s quality is poor then the entire QoE for the call is also likely to be poor. Because QoE is dynamic and we don’t know what the problems will arise, QoE must be measured as per unit over time, all the time. IPTV network scenario Middleware CA Service Live Encoder ATU-R Core Edge Access Network Network Network STB VOD Service NVOD VOD Service Service For simplicity’s sake, the architecture of an IPTV fiber or DSL triple-play network may be divided into four main areas: the head-end, the core network, the access network and the customer’s premises. These four areas offer very good points for measuring and verifying IPTV quality in terms of Service, Perception and Experience. The IPTV signal starts at the head-end where it is encoded before it flows through the core IP network. These are often seen as high capacity optical networks with relatively low utilization, thus problems are rarely seen in this part. More often, issues will be located in the access network or at the customer’s premises, where the signal terminates at the set top box. Watch Your TV Save Your Money
  2. 2. Measurement points In order to establish an IPTV network that works well, it is important to measure the network quality at the above mentioned areas. An IPTV head-end may generate from 20 to 200 IP multicasts streams. Each multicast carries an MPEG-2 / MPEG-4 TV or audio channel. It is necessary to perform continuous monitoring of basic parameters such as MPEG jitter and MPEG-4 / MPEG-2 packet loss at the encoder side of the IP TV head-end in order to determine that the original signal is intact. Having confirmed the source signal quality, the next suitable point for continuous monitoring of the TV signal will be at the border between the core network and the edge network. This should be followed by a monitoring point at the access network, ideally at the customer’s premises. Potential problems Packet loss can occur for a variety of reasons — the network may be congested, there may be a link failure or even insufficient bandwidth. We normally observe packet loss as being bursty in nature, having periods of high loss when network congestion is high. Depending on the protocol being used to carry the video (MPEG-2, MPEG-4 or RTP), we may see different types of quality degradation. However, not all problems are caused by IP impairments. If the server is under dimensioned for the maximum number of expected users, then server congestion can occur. We may observe this as pauses in video playback because the playout buffer level is too low. In order to give a good and proactive picture of the IPTV network, an IPTV network monitoring system must confirm the quality assessment tests and measurements at all network layers, including video quality and a broad range of video distortion and degradation parameters. WatchiTV Distributed is an IPTV network monitoring system that does just this. What is important in terms of IPTV monitoring Monitoring packet drops at the MPEG-2 Transport Stream layer is vital in order to know the percentage of MPEG packets lost when transferring data from a given point on the network to any other given point. Packets may arrive out of order at the destination. IP packet jitter is measured as the variation in arrival time of the IP packet compared to its ideal arrival time. IP packet jitter is a very good source of information in terms of how healthy the signal is when it is transported from source (Encoder) to destination (STB). WatchiTV Distributed measures these parameters and many more in order to give complete visibility into the IPTV network environment. This means network operators can proactively pinpoint errors to assure that subscribers get the picture they expect and demand. At the customer’s premises, the IPTV IGMP Zap Rate is one of the most important parameters to monitor because much of the customer’s perception lies within this value. The EPG system is another important area to estimate performance as well as the VoD service timing at the customer’s site. These parameter must be recorded at the CPE through WatchiTV Portable. Watch Your TV Save Your Money
  3. 3. WatchiTV Distributed Solution: Middleware VOD Service Verify the originating traffic is healthy Inspect traffic quality at border networks Verify the originating traffic is healthy and ability to backtrack problems WatchiTV Probe ATUR STB TV WatchiTV Probe WatchiTV Probe ADSL Core Network Edge Network Live Encoder DSLAM FTTx WatchiTV Probe CA Server WatchiTV Portable solution for on site WatchiTV NMS troubleshooting, ZAP time analysis Portable Edge Network Central data center for monitoring. With remote WEB access WatchiTV distributed is a passive, non-intrusive network monitoring tool that does not generate additional load on the network, yet focuses on all its layers. It enables you to isolate the root cause of a problem very efficiently. Thresholds exceeded will generate alarms and are forwarded to the central network management system where they are processed. SMSes may then be sent to a mobile phone alerting you of an abnormal condition in the network. Most applications for IPTV network monitoring either focus on the lower protocol stack layers or on the MPEG TS information floating in the network. Other applications look at isolated DVB M TR101-290 statistical information. Many choose the intrusive approach of sending IGMP messages into the network in order to request a multicast stream to collect stream information, thus adding unnecessary load on the network. Most solutions don’t support unicast and are not able to display network status, such as Ethernet parameters, CRC Error or Pause Packet WatchiTV Distributed is a Real Time system that takes the best of all approaches. It ensures that you get the most comprehensive information available, presented in a way that gives you the competitive advantage. It ensures that you to stay on top of the network at all times. Being non intrusive, WatchiTV Distributed is beyond a doubt one of the most advanced IPTV network management solutions on the market today. With this complete system, you are able to follow the traffic flow throughout the network from the head-end to the last monitoring point at the access network, before correlating all the information in order to verify the point in the network where the quality is degraded. This helps you to maintain the proactive edge of a high QoS and QoE network. Watch Your TV Save Your Money
  4. 4. WatchiTV Distributed Solution features: - Historic reporting by year, month, week, days and hours - Capture Trigger before and after event; 8M Bytes of data per stream captured for further analysis - Simultaneous analysis of 64 streams per MPEG module (extendable by adding MPEG modules) - Support for IP Unicast/Multicast Stream - Packet Information: size, distribution, fragment, broadcast/multicast/unicast, VLAN, SNAP, MPLS - Web based interface for multiple user access - Period per channel and network status reporting: yearly, monthly, daily WatchiTV Distributed building blocks WatchiTV NMS • 19-inch, 1RU high rack mount • Two multi speed Ethernet: 10, 100, 1000 Mbps • 160 GB hard disk drive for storage of historical data • HTML web browser • SNMP network management system • Size: 620mm x 490mm x 43.6mm WatchiTV ProStation Two multi speed Ethernet: 10, 100, 1000 Mbps • 160 GB hard disk drive for storage of historical data • HTML web browser • SNMP MIB for network management system • 19-inch, 4RU high rack mount • Up to 15 test modules per chassis • Size: 295mm x 485mm x 196mm • PM-2TSF blade: SFP optical interface x 2 • PM-2TSC blade: 10/100/1000 copper x2 ANACISE TESTNOLOGY CORP. Fl. 3, No. 3, Alley 112, Ruei-Guang Rd., Neihu Dist., Taipei 114, Taiwan, R.O.C. Tel : +886-2-2792-8880 E-mail : Fax : +886-2-2792-8058 Web : Note: Specifications subject to change without notice. All product and company names are trademarks of their respective corporations. © 2006 AnaCise Testnology Corp. All rights reserved. Watch Your TV Save Your Money