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Performance Study Of Iptv In Real Network Information Technology Essay

The telecommunication companies will most likely be the first to embrace the Internet Protocol Television (IPTV) technology, since this will help open up a new market for them to survive its role since some of the old services like fixed line service is more likely stagnant nowadays. The added functionality realized through the capabilities of a packet size, two ways television (TV) system will undoubtedly attract a lot of customers. This will put pressure on the normal broadcasting TV industry to adopt similar functions in their systems, which will most likely lead to IPTV over satellite TV. Telco service provider in Malaysia already delivers the packet based Internet Protocol (IP) service to the customer via Digital Subscriber Line (DSL) technology. Since it could provide the service of IPTV by using the legacy technology of DSL but in terms for High Definition (HD) channel, it could not support such a big bandwidth.

Therefore it comes with High Speed Broadband (HSBB) service whereby it could divide into two big platforms which are Fiber to the Home (FTTH) by using Passive Optical Network (PON) technology and Very High Bit Rate Digital Subscriber Line 2 (VDSL2). Both of these access networks could be applicable for wireless at the end of the end user. From now onwards in the thesis, the authors would refer PON technology as FTTH technology. For this paper, it would cover the IPTV and the author had analyzed the performance of the IPTV by using different access medium which are fibers by using FTTH technology and for copper, it using VDSL2 technology respectively. In the same time, the author had tried using wireless connection at the end of user side by using fiber and copper as major access medium.

Experimental Research

The project begins with the IPTV network setup. The IPTV network setup is base on the service provider’s architecture implementation. (Fig.1) describes the network implementation for service provider’s setup overview [2].

Fig.1. IPTV system overview

The tools that had been used at the user’s side for the IPTV monitoring are EXFO AXS200/650 [3] and JDSU HST3000c [4]. This test gear can be used for both FTTH and VDSL2 technologies where by the test gear is just placed before the STB after the PG. These tools can measure the required parameters such as packet loss, PCR jitter, packet jitter, latency and Internet Group Management Protocol (IGMP) latency also known as zapping time at the user’s side.

IQMedia Analyzer [5] was placed at the server’s side. In the same time the IQMedia Analyzer Software will allows the user to inspect and analyze media over IP that flows from a remote test system to a host computer. IQMedia Analyzer run on a host PC connect to the remote test system via a network connection. The Measurements include Media Delivery Index (MDI), bit-rate, packet loss, packet jitter, stream parameter (latency) and more. The IQMedia Analyzer software is installed with IQMediaSuite and must be installed on a computer that will connect to the same network that the system will be on. This Analyzer consists of Network Overview, Media Overview and Cencus. In Network Overview launches several windows that detail raw network information activity present on the link. Media Overview button launches a single window that gives the user quick overview of the traffic on the link from a streaming media perspective. The dialog will list the ports available on the hardware. Each port lists the percentage of utilization used by video streams; the percentage of utilization of all network traffic, the numbers of video streams detected by the hardware and the number of video streams in error or have been in error in the past. The errors are determined by the user setting of stream behavior thresholds through the web page interface. Lastly, the Cencus button launches a single window that gives the user a list of all streams that are being measured by the hardware.

Methodology Implementation

1. Design Implementation

(Fig.3) shows the access path using FTTH which means fiber as a main transmission from exchange to the user side. OLT is one of the key components used in PON networks and the optical line terminal is usually put in the central control room and should give proper monitoring for that equipment performances. The OLT could support maximum 256 ONU and the number of user may vary from different OLT manufacturer. OLT make a stable big bandwidth data transmission over 10 to 20 km distance from the exchange.

The data is transmitted to FDC from OLT. FDC provides outdoor and indoor optical cable, optical terminal equipments with terminal and storage capabilities. The modular structures of FDC offer extremely large flexibility with easy capacity extension. It meets the updating and future developing demands. It sets an independent storage module which may not adopt the intermediate distributing allocation.

Next connection is FDP. It is quite similar to the FDC but it is placed at remote area. From FDP, it is connected to FTB. FTB is suitable for joining fiber with fiber pigtail and protecting fiber optic splices and help to distribute. The terminal boxes are divided into a wall-mounting type, a fixed and flexible type terminal box, which mainly are used in telecommunication equipment room and network equipment room. FTB has internal storage structure that allows storing fiber and fiber pigtail, as well as storing excess active connector of fiber pigtail. Therefore it is easy for capacity expansion.

FWS is applicable to the terminal of indoor cables in the customer premises. From that point, the optical fiber is connected to ONU. ONU provides the users with many kinds of broadband services such as VoIP, IPTV, and high speed internet. ONU is economic and high efficient equipment and play an important role in the FTTH fiber optic network. ONU converts the light signal into the electric signal at the user side and enables reliable fiber optic Ethernet services to business and residential users through fiber-based network infrastructure. For voice service, the phone is connected at ONU instead of PG.

From ONU, there is another device that only applies in Malaysia for IPTV setup configuration which is PG. PG has four RJ45 ports whereby, first 3 ports use for High Speed Internet (HSI) while the fourth port is especially for IPTV. From the fourth port, there is connection to STB. It is a subscriber’s interface to the network and it interprets the incoming signal into format that the television can understand. It also converts the remote control button in IP commands for the desired function. Then from it, the television is connected.

Fig.3. Transmission path of access network using Fiber to the Home (FTTH)

Fig.4. Transmission path of access network using Very High Speed Digital Subscriber Line 2 (VDSL2)

(Fig.4) depicted the setup configuration of IPTV using copper as main transmission medium by using VDSL2 technology. There are two parts of configuration which is related to access network and user side. From Multi Service Access Node (MSAN) until VDSL2 modem, is access network section while PG to television, is user side section. MSAN and Subscriber Distribution Frame (SDF) room is located outside the customers’ premise while Wall Socket (WS) to television is inside the customers’ premises.

MSAN is integrated access equipment that integrates broadband equipment with narrowband equipment. The equipment can provide users with various multimedia services of high quality, such as traditional voice services, broadband access, IP voice access services and IPTV services.

SDF Room is connected to MSAN. SDF Room is functioned as the interconnection point between the building's internal systems and the communications services entering from the inter-building communications system. The SDF Room provides space for wall-mounted and freestanding equipment supporting the centrally-administered communications systems, as well as the point-of-presence for franchised utilities. Normally, SDF Room is located at the high raise building.

From SDF Room a cable is pull out to WS where it is located at the wall of customers’ premises. WS is a distribution point that could connect with RJ11 which is used for telephone services. VDSL2 modem is connected to WS by using RJ11. The phone line is connected to VDSL2 modem instead connecting it through PG. PG is connected to VDSL2 modem and the STB is connected to it.

IPTV could be also viewed at the end of user side by using wireless.

2. Parameters Measurement

For this project there are three types of variables that need to be considered. There are constant variables, changeable variables and reactive variables. For the constant variables, there are four types of fix variable. The first variable is the bandwidth that provides the IPTV service for both Standard Definition (SD) channel and High Definition (HD) channel. For SD channel the bandwidth required are 2Mbps and HD channel are 8 Mbps. For time being, the service provider had offered 15 Mbps to their customer’s that subscribed the IPTV. Secondly, for the compression method, IPTV required the Motion Picture Experts Group (MPEG) version 2 for the physical medium and version 4 for the encoder and decoder. As an access network part the researcher just focuses on the FTTH access network using the PON technologies and VDSL2. Lastly the tools of measurement that required for monitoring the IPTV quality performance are Triple Play test gear that had been measured at the user’s side and IQMedia Analyzer at the server’s side.

As for the changeable variables, there are three kinds of variables. First, the time taken for reading measurement, in this project, the researchers’ took the IPTV reading every one hour starting from eleven o’clock in the morning till five o’clock in the evening consistently and also taken in randomly for a certain experiment because of the time constraint. Secondly, the user distance from the server. There are two different distance was taken from server to end user. Lastly, the usage of the channel which is HD or SD would affect the performance of IPTV. Finally for the reactive variable, this project only focus on the packet loss, packet jitter or IP arrival jitter, PCR jitter, latency or stream parameter MDI- DF, Internet Group Management Protocol (IGMP) Latency and also known as Zap Time.

A. IPTV Metrics

In order to provide the good service as well satisfy users’ requirement, the service provider’s had listed 5 important parameters that really closed to QoS and QoE [6]:

IGMP Latency or Zapping Time is time that it takes for a Multicast group stream to appear at a destination after an IGMP join is issued from the destination. For certain VoIP applications, that use multicast groups to transport video, this can be referred to as channel change time. The threshold value is a border line of the service interruption, it means that, if zapping time is less than the threshold value, it would affect the service that being delivered. It is in standard and satisfies the minimum requirement for the service quality otherwise it would affect the QoS as well QoE.

Latency a synonym for delay is an expression of how much time it takes for a packet of data to get from one designated point to another.

PCR jitter is stand for program clock reference jitter. PCR is fundamental to the timing recovery mechanism for MPEG2 transport streams. PCR values are embedded into the adaptation field within the transport packets. Jitter in the PCR is mainly attributed to two sources: systematic jitter and network jitter. Systematic jitter and network jitter are combined to get overall jitter.

Packet Jitter or packet arrival jitter is an estimate of the statistical variance of the RTP packet arrival time, which is measured based on the RTP time stamp. It also means packet delay variation (PDV). PDV is an important QoS factor in assessment of network performance to ensure that the quality of IPTV at user is not affected.

Packet loss is when an IP packet does not arrive at its intended destination. This can be caused by any number of circumstances: Network Saturation, Network hardware failure and queuing.

B. IPTV Threshold Parameters

Table 2 shows the IPTV threshold parameter requirement by service provider’s where that parameter will be using for QoS and QoE measuring and monitoring purposes.

Table 2. IPTV threshold parameters

Parameter

Threshold

Packet Loss

<0.1%

Jitter ( Packet Arrival Jitter)

<50ms

PCR Jitter

<5ms

Latency (MDI DF)

<200ms

IGMP Latency (Zap Time)

<500ms

3. Monitoring and Measurement

The QoS and QoE is critical key to the overall success of IPTV [7]. It will be an important factor in the marketplace for the success of IPTV services and is expected to be a key differentiator with respect to competing service offerings. Subscribers to network services do not care how service quality is achieved. What matters to them is how well a service meets their expectations for effectiveness operability, availability, and ease of use. Additionally, services provided over a broadband infrastructure must perform at least as well as and preferably superior to competing services using other delivery mechanisms. Consumers tend to be agnostic to broadband transport mechanisms whether they be fiber, wireless, copper cable, and so on as long as the infrastructure does not get in the way of their goals. Analyzing service QoS and QoE requirements and establishing corresponding objective engineering performance targets, is the first step to ensuring end users are satisfied with their services.

QoS is a wide term, often used to describe the overall experience a user will receive over a network. The literature does not offer one common definition of QoS. QoS is defined as “The set of those quantitative and qualitative characteristics of a distributed multimedia system, which are necessary in order to achieve the required functionality of an application [8].” According to the recommendation of the telecommunication standardization sector of (ITU-T) QoS is defined as “the collective effect of service performance which determines the degree of satisfaction of a user of that service [9].” Besides that, QoS also could refers to a set technologies that enable the network administrator to manage the effects of congestion on application performance as well as providing differentiated service to selected network traffic flows or to selected users. QoS mechanisms do not create bandwidth but instead manage available bandwidth more efficiently. It measure from network perspective.

On the other hand, QoE promotes a holistic understanding of quality, as it aims to address all technical and non-technical parameters that contribute to the user experience of networked services. QoE describes the performance of a device, system, service or application from the perspective of the user side. It measures the service level from user perspective.

Even QoS and QoE give different definition, but actually both of it inextricably linked together. For example, increasing video compression reduces bandwidth and therefore improves QoS. Instead the end user perceives lower quality video, therefore QoE is reduced. In a nut shell, QoS is used to approximate the QoE. In general, there is a non-linear relationship between the subjective QoE as measured by the MOS (Mean Opinion Score) as shown in (Fig.5) it shows that, the higher the QoE, then the lower QoS. MOS are typically used as a subjective measurement to quantify the perceptual impact which means the users’ quality of experience of various forms of service degradation. The relation between QoE and QoS metrics is typically derived empirically. Having identified the QoE and QoS relationship, it can be used in two ways:

Given a QoS measurement, one could predict the expected QoE for a user.

Given a target QoE for a user, one could deduce the net required service layer performance.

Fig.5. Inter-relationship of QoE and QoS

Table 2 and (Fig.6) is the quality test with respect to the TCP/IP layers that involved for the monitoring the video quality of IPTV, where VQ is on the layer five of the TCP/IP. QoS is on layer one till layer four of TCP/IP and lastly QoE is on layer five in TCP/IP. In the Application layer at layer five, the major problem is the control problem. As for video problem usually it will occur at application layer and the transport layer which mean layer 4 to layer five. Lastly at layer one till layer three (physical, data link, and network layer). IP problem will occur on that layer. It can conclude that at layer four to layer five is on the customer side and below than layer four is on the network side.

There are several factors that will affect IPTV QoS where each of the resulting is in a poor image quality to the user. First is the network bandwidth where the total of video stream data amount that can be sent is eventually limited by the bandwidth provisioned over the access network. Second is the packet loss where it represents the various levels of image impairments such as the invisible of the missing point of the video sequence to a long period of degraded that caused by the pixilated and unavailable images. Third is the impulse noise where it can lead to a large burst of errors which give an impact on the video quality. Last is the jitter, this phenomenon can affect the MPEG2 and MPEG4 video streams.

Table 2. Quality test on TCP/IP layer

Video Quality (VQ)

Layer 5

Quality of Service (QoS)

Layer 1-4

Quality of Experience (QoE)

Layer 5

Fig.6. Quality test on TCP/IP in details

Conclusion

Based on the research that had been conducted, it was proven that the transmission medium using optical fiber is much better than legacy medium which is copper in all angle of comparison. For instance, the maximum value for zapping time that had been recorded for fiber was 26ms while for copper it was 65ms. For the copper, it needs to use VDSL2 in order to support such a huge big bandwidth. Even though it uses VDSL2, it still has some drawback if compare to optical fiber. However, DSL still remains the most popular access technology, with over 200 million of the world’s, 313 million broadband subscribers connecting via DSL. The global market share of broadband technologies remains largely unchanged from December 2006, with almost 10% using FTTH. The scenario is happened because of the installation cost of optical fiber as well the highway of DSL is already exists. Therefore, the service provider just sticks with DSL technology using copper transmission rather than moving every transmission path to fiber. But for time being, the service provider’s only focuses to certain area to provide IPTV by using FTTH for the future plan.

Acknowledgment

The authors would like to thank the service provider’s and IPTV members for their valuables activities. Special thanks to Mr. Khairul Anuar for his support and guidance towards this thesis.

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