QoS-Guaranteed IPTV Service Provisioning in IEEE ... - IEEE Xplore

3 downloads 1913 Views 389KB Size Report
Abstract— This paper proposes a QoS-guaranteed IPTV service provisioning by differentiated traffic handling in home network IEEE 802.11e/g Wireless LAN.
QoS-Guaranteed IPTV Service Provisioning in IEEE 802.11e WLAN-based Home Network Kye-Hwan Lee ,

Son Tran Trong, Bong-Gyun Lee , and Young-Tak Kim

Dept. of Information & Comm. Eng., Graduate School, Yeungnam University, Korea {kyehwan2, trongson, zakare}@ynu.ac.kr, [email protected]

Abstract— This paper proposes a QoS-guaranteed IPTV service provisioning by differentiated traffic handling in home network IEEE 802.11e/g Wireless LAN. The proposed traffic engineering scheme prioritizes IPTV traffic to provide guaranteed QoS in the inter-mixed and congested traffic condition. Prioritization of traffic is provided by assigning differentiated access category to each packet according to predefined QoS class. When generating multimedia video data, the IPTV server prioritizes user data by setting ToS field of IP datagram to be able to distinguish the multimedia traffic from usual best effort traffic in the home network. This paper provides detailed explanation of classification and mapping of multimedia traffic on home networks, based on access categories of IEEE 802.11e Wireless LAN. Performance evaluations show that IPTV MPEG-2 traffic, encoded at about 2Mbps bitrate, can be delivered with guaranteed QoS even when the aggregated traffic reaches up to 20Mbps in IEEE 802.11e/g WLAN access point. The received video traffic has a quality that is good enough to satisfy users, and QoE(Quality of Experience) of received video is verified by VQM(Video Quality Metric). From the series of experiments, we found that the proposed differentiated traffic engineering for IPTV service can provide QoS-guaranteed real-time service in home network with Wireless LAN. Index Terms—IPTV, QoE, Set-Top Box(STB), Subjective Assessment, Traffic Engineering, VQM

A

I. INTRODUCTION

S the user home network capacity grows, it has become possible to provide various multimedia service requiring high bandwidth. Though the total bandwidth grows, multiple communication sessions(e.g. VoIP, IPTV, Internet Web browsing, FTP, E-mail, etc.) may cause traffic congestion in the home network. If the home network is based on a Wireless LAN environment, congestion will become worse because of channel contention among wireless devices. Unless a regular bandwidth cannot be maintained on delivering IPTV traffic, unstable bitrate may affect real-time sensitive IPTV service quality, which cannot provide satisfaction of users. That is why the home network requires the traffic engineering technology for QoS-guaranteed service provisioning with better video quality. Contrary to an existing telephone service, IPTV service has

to deliver user traffic within a limited transfer delay. For example, real-time voice and video data should be delivered within 500ms by IPTV service, and channel control, such as channel zapping, must be satisfied in 2 seconds[1]. Especially with uncertain network environment with wireless contention, we should consider that IPTV transmission has to maintain a bandwidth over 2Mbps for MPEG-2 data stream. The actual goodput available to application is almost halved in IEEE 802.11g Wireless LAN due to MAC contention[2]. Therefore, in order to provide the QoS-guaranteed service, a traffic engineering must be used to guarantee more than 2Mbps for IPTV data stream regardless of congestion. In order to efficiently provide clients with a satisfying IPTV service and to maintain a high level QoE(Quality of Experience), which refers to the user’s perceived quality of provided service[3], user data should be prioritized depending on their service category[4]. For example, normal data may be categorized as best effort service, while real-time sensitive service should be classified as higher priority traffic to keep specified limitations. Therefore, traffic engineering can be applied to ensure video quality by using the access category under the limited and fluctuating bandwidth of Wireless LAN. Mixed data can be distinguished according to their priority at the home network gateway. Classification of mixed data is an important factor in improving real-time video quality. However, it is hard to prove how much bandwidth should be reserved for QoS-guaranteed flow. It is somewhat difficult to give a precise metric because the video quality that the user senses is actually dependent on individual human perception. Because of the subjectivity of video quality, we must learn to measure IPTV video quality objectively. This paper adopts VQM(Video Quality Metric) as an objective estimation method for video quality at J.144 standard, Annex D[5]. To verify the effectiveness of classification at the home network gateway for IPTV data delivery, we configured the wireless home network system with a wireless access point and wireless end-terminals. Prioritized packets could be generated by predefined QoS class[6] at the IPTV server and sent to the home network. We analyzed how each prioritized flow was guaranteed even when congestion occurred. VQM that represents user’s QoE was calculated at the receiver side[7]. The rest of this paper is organized as follows: Section 2

978-1-4244-2067-4/08/$25.00 ©2008 IEEE.

71

provides related work and major issues in IPTV service network. Detailed description of the IPTV system model and overall IPTV service configurations and proposed architecture are explained in section 3. Section 4 continues and analyzes the experiments in the wireless home network. Finally, section 5 concludes this paper. II. RELATED WORK Ordinary IPTV transmission system has focused mostly on transmission itself and the quality of user perception has been ignored in many cases. But even so, it is hard to measure the exact current network status and to guarantee the quality of user requested video data, especially IPTV. Considering wireless home network, it is required to distinguish real-time multimedia traffic from the best effort non-realtime traffic, otherwise the quality of real-time sensitive data may not be guaranteed because of network congestion. To guarantee bandwidth for real-time data traffic separately at the user home network among mixed data traffic, the home gateway should be able to distinguish the packet type. In the previous research about access network traffic control[8], the Access Network Interface(ANI) classified the traffic into multicast and unicast according to their target MAC address, which connected to the specified port to switch in separate way. However, ANI has to pre-configure a forwarding table to match entering packets to the defined port in advance. If predefined forwarding table doesn’t exist in gateway, multimedia data can not be separated even if the video data is entered. Considering addition of wireless interface, the guaranteed service may not be treated as the multicast traffic until the registration process is completed. It is difficult to apply the method of MAC forwarding table to the wireless home network environment because wireless devices can occasionally vary. Therefore, it is more efficient to distinguish traffic type at the packet generation procedure of multimedia server. QoS-guaranteed IPTV service mechanism was proposed in [9]. To guarantee service, they proposed connection admission control that is controlled according to the remained bandwidth. If the bandwidth is enough to allocate a new flow, a connection will be provided. Once the connection is established, it might be certainly guaranteed, but these policies cannot be applied when there are several traffic classes which have different levels of QoS, because this scheme guarantees only the throughput related to the total bandwidth ignoring the multimedia characteristic. It might happen that the normal data cannot be guaranteed instead of the desired multimedia data, that is, the differentiation between them does not applied. Therefore, end-to-end Qos-guaranteed service provisioning needs somewhat different strategies in home networks. In this paper, we propose prioritization of packet at the server and differentiated traffic engineering at home gateway. By inserting access category according to QoS classes, traffic differentiation can be implemented at the user home network. The quality of experience about the real-time sensitive IPTV service can be certainly guaranteed even though congestion

occurs. This suggested scheme can be used when there are several types of traffic with different level of required QoS. Another consideration is the measurement of quality of experience(QoE) as the throughput increases gradually. The majority of previous researches have mentioned only the total traffic flow not considering individual video quality. They didn’t consider the video quality when multimedia traffic traverses through the network to users. Even though the required throughput of the multimedia traffic is guaranteed, the video quality that user perceives might be degraded due to the high jitter-deviation. Therefore, it is necessary to evaluate the exact quality of experience for received video. A subjective video quality assessment was performed with various jitter-deviation[10]. Although controlling the jitter-deviation was used to keep video quality at the subjective quality rating[10], the quality rating that needs many participants’ assessment is not efficient to apply to the real-time processing. We adopted VQM[5] to measure exact video quality, and it is very efficient way to show the relationship between the video quality and network QoS parameters. III. QOS-GUARANTEED IPTV SERVICE PROVISIONING BY TRAFFIC DISCRIMINATION AT HOME NETWORK A. Proposed IPTV Traffic Management Scheme An IPTV end-terminal may be a wireless device attached to IEEE 802.11 Wireless LAN. In home network with a Wireless LAN gateway, there are many complicated issues such as bandwidth limitation, packet drop or loss by contention, and fluctuating service quality. This section aims to understand how to guarantee real-time video quality in Wireless LAN home network. Firstly, Wireless LAN has difficulty in supporting high quality video transmissions because the bandwidth has limited capacity by wireless specific features, e.g., wireless MAC contention[2]. Secondly, if a home network has a lot of wireless terminal equipments, packet drop rate may increase by the contention at the MAC level. Quality degradation may occur so that the Service Level Agreement(SLA) cannot be kept any longer. So it is important to know how to provide reliable service that gives clients satisfaction in IEEE 802.11e/g WLAN environment. The configuration of a home network system based on IEEE 802.11e/g is a way in which all its parts, such as media server and user client, should be considered together for guaranteed IPTV management. Another important factor is differentiation of each data flow, which is determined during the packetization procedure in Fig. 1. In order to guarantee the differentiated priority of user flows, it is necessary to allocate proper priority when sending video streaming data. Then an access point in the home network that supports IEEE 802.11e/g(QoS-guaranteed Wireless LAN[11]) can classify each traffic by their priority. Fig. 1 shows some considerations about the whole procedures for guaranteed service delivery system. Media Server prepares IPTV and multimedia service data in the various encoded

72

Media MediaServer Server IPTV, IPTV,Multimedia Multimedia

Packetization Packetization

MPEG -2: SD 2~8 Mbps MPEG -2: SD 2~8 Mbps HD: 15~18 Mbps HD: 15~18 Mbps AVC SD 1.5-3 Mbps AVC SD 1.5-3 Mbps HD 8 ~ 12 Mbps HD 8 ~ 12 Mbps

Service Service Provider Provider Network Network

Fig. 1.

RTP/UDP/IP RTP/UDP/IP

Home HomeGateway Gateway Wireless WirelessAP AP

• Streaming Connection • Streaming Connection • Traffic Priority • Traffic Priority • IP ToS Field • IP ToS Field • Network Time Protocol • Network Time Protocol

Regional RegionalTransport Transport Network Network

User UserClient Client SLA, SLA,QoE QoE

•IEEE 802.11e QoS •IEEE 802.11e QoS •Traffic Engineering & •Traffic Engineering & Classification Classification •VQM calculation •VQM calculation • Error Concealment • Error Concealment •QoE for users •QoE for users

Access AccessHome Home Network Network

Considerations for Guaranteed Service Delivery System

format. Before sending data, traffic priority allocation must be prepared for supporting guaranteed service provisioning at the packetization procedure. And RTP-over-UDP can be sent to the user home network through the transport network while the server and set-top box are synchronized to NTP(Network Time Protocol). If the home gateway has a traffic collision, some of packets will be dropped or delayed. It must affect on the service quality. So, the traffic engineering function is needed at the user home network in order to guarantee the quality of experience of the video data. For this purpose, we configured a IPTV test bed network using an IEEE 802.11e/g environment that has a 54Mbps physical layer transmission rate, as shown in Fig. 2. The throughput might be even less than 20Mbps as contending wireless terminals increase in number. To test the guaranteed QoS provisioning of IPTV traffic, we used three wireless connections to cause throughput decrease as total traffic reaches at saturation level. One is targeted real-time IPTV network traffic and another is best-effort traffic, and the other is just background data. Transit routers are IP/MPLS backbone networks, 100Mbps link connected to user home network. Through regional transport network, packets are typically routed and forwarded a number of intermediate routers. So it is hard to keep constant bitrate until arriving at the destination home network. If the bitrate is seriously fluctuated, it may have a bad effect on providing good service quality. It is assumed that the servers is connected to the public network based on wired networks, while the user home network, is a wireless network where multiple contending terminals have their own path. Also, the home network is assumed to have one AP(access point), which supports IEEE 802.11e/g. The IPTV media sender may have different sources in the same way. We measured the quality of IPTV flow while gradually increasing the background best-effort traffic. B. Requirements for Guaranteed Service Traffic and Standard of Quality Estimation The service provider needs a specific metric measurement that can indicate the guaranteed-QoS service provisioning. So, in order to clearly measure video quality, we must know how to objectively measure the IPTV video quality. It is somewhat difficult to express the metric in simple data because video qualities that end user senses are actually dependent on individual human perception.

The general scheme to express the subjective video quality perception from objective measurements is needed. In ITU-T J.144 Standard, Annex D, NTIA(National Telecommunications and Information Administration) suggested VQM(Video Quality Metric) as an objective estimation method for video quality[5]. It is one method of closely expressing a correlation between subjective and objective assessment. In addition to providing perception-based estimates of subjective quality, the VQM has been adopted as a useful metric for continuous real time in-service quality monitoring applications[12]. Although other traditional methods have been used, such as SNR(Signal to Noise), RMSE(Root Mean Square Error), yet VQM more closely corresponds with user’s satisfied video quality, because SNR and RMSE are only focusing on comparing calculations among electric components at each frame. But from the user’s perspective, the value of SNR is insufficient to give the quality information. However, VQM which can compare spatial, temporal and color features is the best attractive way to measure video quality as the objective assessment and to reflect subjective parameters. For example, in comparison of SNR or RMSE with VQM, several noise images have very different levels of distortion, while the RMSE distortion is the same. But VQM distortion is proportional to the observer’s impression by spatial, temporal and color continuity[13]. The less VQM values appear, the better Quality is measured. Therefore, if the VQM value turns out to be less than 1, it means better video quality that the user senses. In order to support IPTV video quality with regards to traffic engineering, traffic flows should be differentiated by priority. The higher priority traffic must be allocated with network resources with higher priority. It is assured that IPTV traffic must have relatively high priority than others because of its real-time and jitter-sensitive features. C. Classification of Multimedia Traffic To classify incoming data for traffic engineering at the home network interface gateway (e.g., the access pointer of IEEE 802.11e/g network), the media server must generate priority according to traffic specification. Before sending the data to public network, packet classification must be completed. Priority can be divided into some categories as shown in Table I. Y.1541 QoS class[6] table shows usual internet traffic such as FTP and E-Mail as BE(Best Effort) service are classified as QoS class 5, while realtime interactive(RTI) services, such as VoIP and video phone, are classified as QoS class 0/1. Real-time interactive service must be highest class priority. Among real-time interactive services, IPTV is classified as the most significant grade, because IPTV has real-time video and audio features simultaneously and also it needs interactive control, such as channel japing. For supporting different priorities, the VLC(Video Lan Client) media transmitter program[14] was modified so that it can specify different priority at ToS(type of service) field in IPTV packet. Then, user data, each marked with different priority, can be sent to the client home network while being

73

1 0 .4 0 . 1 0 . 1 0 / 2 4 1 0 . 1 1 0 . 1 0 . 2 /2 4

S tre aming re c eiver

S trea ming se rver

P O S 4 /0 1 0 . 8 0 . 1 0 . 1 /2 4

1 0 . 4 0 .1 0 .3 0 / 2 4

S trea ming rece ive r

S SI D: A NT L ab_ 1 K ey : 0 538 1024 97

FE 1 /0 10.40.10.2/ 24

P O S 1 /2 1 0 . 9 0 . 1 0 . 1 /2 4

P O S 1 /1 1 0 .8 0 . 1 0 . 2 / 2 4

7 2 04 _ F

G EE W A N 2 /1 1 0 . 2 0 . 1 0 . 2 /2 4

P OS 3/0 1 0 .9 0 .1 0 .2 /2 4

6 50 6 _ C

6 5 0 6 _B

G E - -W A N 2 / 1 1 0 . 2 0 .1 0 .1 /2 4

P O S 4 /0 1 0 . 1 3 0 . 1 0 . 1 /2 4

FE 0 /0 1 0 .1 1 0 .1 0 . 1 / 2 4

6 5 06 _ A

S trea ming s erver

7 20 4 _ H

1 0 . 4 0 .1 0 .2 0 /2 4

10.110.10.3/ 24

T raffic rec e ive r

Fig. 2.

1 0 .1 1 0 .1 0 .4 /2 4

P O S 1 /2 1 0 . 1 3 0 . 1 0 .2 /2 4

T raffic g enera tor

Wireless Network Configuration on Transferring IPTV data

guaranteed as long as the access point discriminately classifies user data. So we can give the designated priority to encoded video data stream and it is possible to send prioritized data to client. If the data reaches the home network, the access point enabled to support IEEE 802.11e QoS enhancement can differentiate traffic flows into each data according to their priority. IV. PERFORMANCE ANALYSIS A. Test Result Analysis –Guaranteed Service Provisioning The above mentioned test-bed in Fig. 2 provides the configuration with wireless access point at client’s home network, intermediate routers and streaming terminals at both edges. We have two different video streams. One is AC_VI(QoS-aware) with high priority for the video service, and the other is AC_BE(Best Effort) with low priority for the best effort traffic. The video data that we used for the MPEG-2 format has around 2Mbps average data rate. With this configuration, we tested the same video traffic with different priorities, respectively, while the other flow assumed as best-effort background traffic increased gradually. The results could be measured at the client point that calculated delay, jitter and packet loss ratio by using packet capturing. Fig. 3(a),(b) shows the each traffic throughput and packet loss rate dependent on defined priority. As aggregated flow increased up to 17Mbps, each flow is constantly maintained about 2Mbps. Also AC_VI shows that video traffic is fully guaranteed at the very low loss rate. When the aggregated traffic is increased beyond 17Mbps in Fig. 3(a), best effort

traffic decreases gradually due to packet drop. In Fig. 3(b), best effort traffic shows severe loss increase while the packet loss rate should be maintained less than 10-3 for providing smooth satisfied service[6]. When the aggregated traffic greater than 17.5Mbps, the AC_BE cannot guarantee video service quality due to the excessive packet loss. In Fig. 4, if the aggregated throughput is over than the saturation level of wireless limited capacity, the average delay and jitter is getting increased. If the average delay increases, the average delay variance is supposed to increase. In our experiments as shown in Fig. 4(a), both the average delays(AC_VI and AC_BE) increases as the aggregated throughput increases. The average jitter of AC_VI with higher

(a) Throughput vs. Aggregated traffic

TABLE I ASSOCIATION OF IPTV SERVICE WITH Y.1541 QOS CLASSES IPTV service category

IP QoS class

IPTV service examples

QoS parameters

content download service Best Effort (BE) service

QoS class 5

regulatory information service T-information

Unspecified

e-mail Download VOD, MOD Low Loss (LL) service

QoS class 4

T-commerce

Mean delay ≤ 1 sec Loss ratio < 10-3

T-learning based on VOD Interactive (I) service

QoS class 2/3

Real-Time Interactive (RTI) service

QoS class 0/1

messenger T-learning based on interactive VOIP, video phone multi player game

Mean delay ≤ 400ms Loss ratio < 10-3 Mean delay ≤ 100ms Jitter ≤ 50ms Loss ratio < 10-3

linear/broadcast Real-Time Multicast & Unicast (RTMU) service

multi angle QoS class 6/7

pay per view (PPV) networked personal video record (PVR, time-shift)

Mean delay ≤ 400ms Jitter ≤ 50ms Loss ratio < 10-5

(b) Packet loss ratio vs. Aggregated traffic Fig. 3. Network QoS parameter(packet loss) according to increase of aggregated traffic in wireless IPTV network configuration

74

priority didn’t increased abruptly, but maintained at a certain level as shown in Fig. 4(b). Therefore, the video quality of VC_VI has better than the AC_BE traffic. When the aggregated traffic load is less than 18Mbps, as shown in Fig. 4(b), there is no difference in jitter value. However, as the traffic load increases beyond this point, the jitter of AC_BE grows gradually. The best effort traffic with low priority cannot be guaranteed beyond the saturated point, because the average jitter increased suddenly to high level, while the video traffic with high priority maintains the constant level of average jitter even though the total bandwidth reaches 22Mbps at home network. This analyzed result can be applied for supporting the differentiated real-time IPTV service provisioning in wireless home network. In order for guaranteed video service, the server has to prioritize multimedia stream according to predefined QoS class at the source packetization procedure. So, if IPTV subscriber has an access point supporting IEEE 802.11e/g at the home network gateway, the differentiated IPTV traffic can be guaranteed to satisfy the good quality condition with high access priority. B. Comparing Experimental Results with QoE In order to satisfy the requested service quality, there are some strict conditions in multimedia transmission. In case of IPTV, limited delay variance(jitter) must be kept when the real-time multimedia data is delivered to users, otherwise video and audio cannot play smoothly because of abrupt change of packet delay. In other words, the increased delay variance makes video quality go from bad to worse increasingly. The jitter of IPTV data must be limited within a certain level. The packet loss rate also must be maintained while the total throughput is guaranteed. The detailed specifications are explained in ITU-T Y.1541 recommendation, as shown in Table II. Considering guaranteed IPTV service provisioning in its QoE aspect, QoS class 0 or 1 jitter must be under 50ms at least, and packet loss rate also must be kept at10-3, respectively. If these minimum limitations are not fulfilled, it is hard to get the satisfied video service. C. Evaluations of QoE for Real-time QoS-Guaranteed Service Provisioning according to Jitter and Packet Loss This research experiment simultaneously considers QoE-user perceived quality as well as guaranteed service. For more precise quality of video measurement, we adopted VQM measurement[5], which could compare subjective assessment to objective assessment. In order to examine the relation between VQM and network QoS parameters(delay, jitter and packet loss), it is necessary to have standard comparison with network QoS parameters. For this experiment, VQM proportional to each parameter had been measured as shown in Fig. 5. Fig. 5(a) shows VQM value related to each STB buffer size as the average jitter increases. The larger STB size is, the less VQM is at the same average jitter point as shown in Fig. 5(a). From this analysis, we can see that if the STB buffer size is designed for amount

(a) Average Delay vs. Aggregated traffic

(b) Average Jitter vs. Aggregated traffic Fig. 4. Network QoS parameters(delay, jitter) according to increase of aggregated traffic in wireless IPTV network configuration

of 30ms, the network jitter should be less than 24ms in order to maintain the VQM less than 1. In Fig. 5(b), we can find the packet loss rate should be less than 3×10-3 in order to maintain the VQM value less than 1.0. Under real network environment, packet loss is often generated by node/network congestion. If packet loss could occur in consecutive video stream data, video frame information will inevitably be distorted. In real IPTV system error concealment is added to handle frame losses[15]. TABLE II QOS CALSS DEFINITIONS AND NETWORK PERFORMANCE OBJECTIVES QoS class

IPTD

IPDV

IPLR

IPER

IPRR

0

100 ms

50 ms

1 x 10-3

1 x 10-4

-

Real-time, jitter sensitive, high interaction (VoIP, VTC)

Applications (examples)

1

400 ms

50 ms

1 x 10-3

1 x 10-4

-

Real-time, jitter sensitive, Interactive

2

100 ms

U

1 x 10-3

1 x 10-4

-

Transaction data, highly interactive (Signalling)

3

400 ms

U

1 x 10-3

1 x 10-4

-

Transaction data, interactive

4

1s

U

1 x 10-3

1 x 10-4

-

Low loss only (short transaction, bulk data, video streaming)

5

U

U

U

U

-

Traditional applications of default IP network

6

100ms

50 ms

1 x 10-5

1 x 10-6

1 x 10-6

High bit rate, strictly low loss/error (TV broadcast on IP)

7

400ms

50 ms

1 x 10-5

1 x 10-6

1 x 10-6

High bit rate, strictly low loss/error

Y.1541 IP network QoS calss definitions and network performance objectives/ Applications(IPTD: IP Packet Transfer Delay, IPTV: IP Packet Transfer delay Variation, IPLR: IP Packet Loss Rate, IPER: IP Packet Error Rate, IPRR: IP Reordered Ratio)

75

VQM vs Jitter 5 4.5 4 3.5 VQM

3 5ms-Buffer

2.5

10ms-Buffer

2

15ms-Buffer

1.5

20ms-Buffer

1

25ms-Buffer

0.5

30ms-Buffer

0 0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

40

Aver Jitter (ms)

(a) Jitter vs. VQM Average VQM vs. Loss ratio 3

Average VQM

2.5 2 1.5

service by using the access category at the wireless home network. In order for QoS-guaranteed service provisioning, the server must classify mixed data into each prioritized flow when transferring. Then, the IPTV traffic with higher priority can be assured at the home network. In our experiments, as the aggregated throughput reached the saturation point of IEEE 802.11g wireless capacity, which is around 18~20Mbps, the packet loss rate of higher priority could be maintained at less than the acceptable 10-3, while the other best-effort traffic experienced increased packet loss. And high priority video traffic could also have low jitter value that is good enough to provide desirable QoE, which is proved by adopting VQM method to express user dependent perception. The VQM value of guaranteed IPTV quality became to be less than 1, while that of best effort traffic was over 4 under the same condition. This result shows that by using the proposed scheme, QoS-guaranteed real-time multimedia service can be provided to users with satisfied video quality within the home network.

1

REFERENCES

0.5 0 9. 02 0 E 9. -0 5 02 0. E -0 00 01 5 0. 353 00 0 0. 361 00 0. 0 85 00 8 09 0. 48 00 6 0. 0 9 00 94 1 0. 129 00 6 29 0. 45 00 3 0. 3 3 00 11 3 0. 62 00 96 4 0. 17 00 88 47 0. 256 00 0. 4 72 00 4 9 0. 776 00 2 48 0. 00 676 50 0. 4 01 94 2 0. 109 01 2 31 40 9

[1]

Loss ratio

(b) VQM vs. Packet Loss Ratio

[2] [3]

Analysis of measured QoS parameters affecting video quality

[4]

As a simple error concealment, we used the ‘frame copy’ scheme that is the most general error concealment method (JM has implemented as a standard[16]). We used this simple error concealment with frame copy to enable VQM measurement even at damaged frames. If advanced error concealment is used at IPTV set-top box, the better QoE can be obtained, but this is beyond the scope of this paper.

[5]

V. CONCLUSION

[9]

Fig. 5.

This paper proposed QoS-guaranteed service provisioning for IPTV service using an IEEE 802.11e/g Wireless LAN access point capable of differentiating multimedia traffic by priority in user home network. Because IPTV MPEG-2 encoded data must be differentiated with 2Mbps bandwidth in order to provide users satisfied quality, a traffic engineering scheme was used for guaranteeing IPTV throughput at the home network gateway for avoiding degradation caused by possible congestion. When generating multimedia video data, the server prioritizes user data at ToS field of IP datagram, so the video traffic can be distinguished from usual best effort Internet traffic at the end user. For this, we could mark the predefined priority of Y.1541QoS class into ToS field in IP packet by using modified VLC source. Then highly prioritized IPTV data can be guaranteed at the home network regardless of network congestion. The proposed scheme has focused on QoS-guaranteed IPTV

[6] [7] [8]

[10] [11]

[12] [13] [14] [15] [16]

C. Hoene, H. Karl, and A. Wolisz, “A perceptual quality model intended for adaptive VoIP applications,” Wiley International Journal of Communication Systems, vol. 19, no. 3, pp.299-316, 2006. Yan Zhang, Jijun Luo, Honglin Hu, Wireless Mesh NetworkingArchitectures, Protocols and Standards, Auerbach Publications, 2007. DSL Forum TR-126, Triple-play Services Quality of Experience (QoE) Requirements, Dec. 13, 2006. ITU-T SG12, “Performance and Quality of Service,” Meeting in Geneva from 17 Oct. 2005. ITU-T J.144 (2003), “Objective perceptual video quality measurement techniques for digital cable television in the presence of a full reference”. ITU-T Recommendation Y.1541 – Network Performance Objectives for IP-based Services, Feb. 2003. Marcio Meiblas Zapater, Graca Bressan, “A proposed approach for quality of experience assurance for IPTV,” in the Proc. of First International Conference Digital Society( ICDS'07), pp.25, Jan. 2007. Min Ho Park, YeonJoon Chung, Wan Ki Park, Eui Hyun Paik, “A Novel QoS Guaranteed Mechanism for Multicast Traffic Controls in the Home Network,” in the Proc. of 2006 IEEE International Symposium Consumer Electronics(ISCE ’06), pp.1-6, Sep. 2006. A. H. Park, J. K. Choi, “QoS guaranteed IPTV service over Wireless Broadband network,” in the Proc. of 9th International Conference, Advanced Communication Technology(ICACT), pp. 1077-1080, Feb.12-14, 2007. Y. Kukhmay, K. Glasman, “Video over IP networks : subjective assessment of packet loss,” in the Proc. of 2006 IEEE International Symposium Consumer Electronics(ISCE ’06), pp.1-6. 2006. IEEE 802.11 committee, “IEEE Standard for Information Technology Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements part 11: Wireless LAN Medium Access Control(MAC) and Physical Layer(PHY) specifications Amendment 8:medium access control(MAC) quality of service enhancements,” IEEE Std 802.11e, Nov. 2005. ITU-R BT.601-5 (1995), Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios. Feng Xiao, “DCT-based Video Quality Evaluation,” Final project for EE392J, Digital Video Processing, Stanford University, 2007. VLC, http://www.videolan.org. Elecard Video Quality Estimator, http://elecard.com. S. K. Bandyopadhyay, Z. Wu, P. Pandit and J. M. Boyce, “Frame loss error concealment for H.264/AVC,” 73rd MPEG meeting and 16th JVT meeting, Joint Video Team (JVT) of ISO/IEC MPEG and ITU-T VCEG, JVT-P072, July 2005.

76