Distribution of Multimedia Data Over a Wireless Network (DMDoWN): An Introduction Presented By: Rafidah Md Noor Faculty of Computer Science & Information Technology University of Malaya Kuala Lumpur

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 2 Introduction: Wireless Network

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 3 Introduction: Wireless Standard Defines a local area network that provides cable-free data access for clients that are either mobile or in a fixed location at a rate up to Mbps Specifies that the features of a WLAN be transparent to upper levels of the standard; all WLAN functions are performed in the PHY and MAC layers

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 4 IEEE Standard

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 5 Introduction: Multimedia Applications Video and Audio Streaming Delivery of news, entertainment, remote education, documentary, fashion shows and many more types of communication. Television is the most well known form of streaming video (dishes and antennas). Streaming technology is important – users do not have access to enough connection capacity to download large multimedia files quickly. E.g. Real Audio, Microsoft Media Player, QuickTime

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 6 Introduction: Multimedia Applications and Multimedia Messaging Allowed users to send messages, pictures, graphics, video and audio files to each other. SpotLife ( develop video communities for wireless carriers. Wireless Gaming Sega, Nintendo and Disney have started to target mobile wireless devices as an important part of their game development strategy. Gladiator is a wireless multiplayer combat game set in the Coliseum of ancient Rome.

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 7 Quality of Service (QoS): Bandwidth Parameters: Bandwidth Data rate generated by the application Measured in the number of bits per second (bps) Bandwidth: the network resources that needs to be properly managed and allocated to applications. Video quality are varying by the following video properties (frame size, frame rate, color depth and compression)

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 8 Quality of Service (QoS): Delay Parameters: Delay (latency) Direct impact on users’ satisfaction. Real-time applications require the delivery of information from the source to destination within a certain period of time. Types of delay: Source-processing delay, transmission delay, network delay, destination processing delay.

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 9 Quality of Service (QoS): Delay End-to-end Delay Diagram Time Data unit is generated at source device Processing Delay Transmission Delay Network transit Delay Processing Delay First bit transmitted to medium Last bit transmitted to medium First bit received at destination Last bit received at destination Data unit playbacked at destination device

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 10 Quality of Service (QoS): Delay Variation Parameters: Delay variation A QoS metric that refers to the variation in the delay introduced by the components along the communication paths. Packets travel in the network using different paths; network conditions for each packet can be different.

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 11 Quality of Service (QoS): Delay Variation Network Time Reference Original Traffic Sender Receiver Delay Jitter Traffic (A) (B) (C ) Missing Packet Adjust the playback point Playback Traffic De-jittered buffer

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 12 Quality of Service (QoS): Loss Parameters: Loss (error rates) Packet loss directly affects the perceived quality of the application. At the network level, packet loss can be caused by network congestion. Several techniques to recover packet loss: Retransmission, Error Correction, Codec.

The National Seminar of Science Technology and Social Sciences, Kuantan, Pahang Darul Makmur 13 Discussion The bandwidth is the main network resource that needs to be distributed to all applications in a way that simultaneously satisfies all QoS requirements. To enable QoS services, there are two main approaches based on how they deal with bandwidth planning. Bandwidth over-provisioning: higher bandwidth Bandwidth management: using QoS mechanism