Providing Network Video Service to Mobile Hosts Bruce A. Mah - - PowerPoint PPT Presentation

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Providing Network Video Service to Mobile Hosts Bruce A. Mah Srinivasan Seshan Kimberly Keeton Domenico Ferrari Randy H. Katz {bmah,ss,kkeeton,ferrari,randy}@CS.Berkeley.EDU University of California at Berkeley Computer Science Division Y

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Providing Network Video Service to Mobile Hosts

Bruce A. Mah Srinivasan Seshan Kimberly Keeton Domenico Ferrari Randy H. Katz {bmah,ss,kkeeton,ferrari,randy}@CS.Berkeley.EDU University of California at Berkeley Computer Science Division Hitachi-Tenet Meeting 10 November 1993

H E

N I V E R S I T Y

A L I F O R N I A

8 6 8

E T T H E R E B E L I G H T

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Outline

Infopad Overview Video Service

Use of a disk array for high-throughput, high-capacity storage
Storage of multi-resolution video data

Network Services

Connection-oriented network protocols supporting performance

guarantees

Connection re-routing to support host mobility

Research Issues in Mobile Computing

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Future Computing Environment

VIDEO SERVER Compressed Video

Backbone Internetwork 100 Mbps - 1 Gbps

BASE

Portable Multimedia Personal Workstations Terminals

INFORMATION SERVERS STATIONS

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Project Focus

Integrate communication and computation Minimize power consumption

Multimedia Terminal

Text and graphics Downlink video Speech input/output Pen input

InfoPad Overview

Antenna RF Transceiver Video Decompression/ Display Driver Speaker Packetizer/ Error Correction Speech Codec Microphone Integrated Pen Input Pad/ Flat Panel Display Battery

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Video Service to Mobile Clients

Video File Service Disk arrays for high-throughput, high-capacity storage Multi-resolution video for heterogeneous clients Network Services Connection-oriented network protocols for performance guarantees Connection re-routing for host mobility

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High Throughput from Disk Arrays

String Controller String Controller String Controller Array Controller Concurrent access High-bandwidth transfers from multiple disks in parallel by independent users

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Multi-Resolution Support for Heterogeneity

Multiple resolutions of video data stored on server Data provided closely matches requested QoS parameters

10 20 30 40 50 60 70 80 90 10 20 30 40 50 60 70 Missed Retrieval Deadlines Number of Users Single Resolution Multiple Resolutions

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Connections for Multimedia Communication

Multimedia data different than traditional data

Periodic traffic patterns Well-suited for stream-based communication protocols Need predictable performance Bandwidth, delay, delay jitter, packet loss due to congestion

Mechanisms to guarantee performance

Per-stream network resource allocation Per-stream admission control

Requires connection-oriented network layer protocols

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The Connection Handoff Problem

A handoff occurs when a host moves between adjacent cells. The Handoff Problem: How to reroute network connections during cell transitions?

Base Station Video Server Switch Room-sized Wireless Network Cell

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Multicast-Based Re-Establishment

Make connection modifications local to the cell transition site Exploit the existing dynamic multicast facilities of a network to support handoff Provides support for “soft handoff”

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Video Service To Mobile Clients

Infopad Overview Video Service Disk array storage for high-throughput, high-capacity storage Multi-resolution video data to support heterogeneous clients Network Services Connection-oriented network protocols for performance guarantees Connection re-routing to support host mobility

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Research Issues in Mobile Computing

Architecture: How to divide functionality between the mobile and the supporting infrastructure? Stateless vs. Stateful: Should the mobile have state? Applications: How are they different for mobiles? Communication and networking: What is the right communication paradigm?

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Architecture: Division of Functionality

Applications influence requirements for architecture Video playback application:

Mobile host is “disconnected-rarely terminal” Computation and storage focused in wired backbone infrastructure Network responsible for re-routing and maintaining mobile connections

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Mobile Host: Stateless vs. Stateful

State kept in mobile host depends on reliance upon wired backbone infrastructure Video playback application:

Network state necessary for network connections to mobile host Little data state required by playback applications Video buffering for inter-frame compression and/or display No consistency problems for read-only data Display can resynchronize with data stream if necessary Display manager state

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Mobile Applications

Application mix will be different on mobile hosts and workstations Mobile applications will require:

More access to existing data Less creation of new data

Video playback application:

Choice of compression scheme influenced by: Mobile host compute resources Wireless link bandwidth constraints Wireless link error rates Client heterogeneity handled well by multi-resolution video storage

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Multimedia Mobile Networking

Connection-oriented network protocols

Provide performance guarantees for multimedia data

Video playback and other information services:

Require disconnected-rarely (i.e. mostly-connected) operation Allow asymmetric communication on wireless link High-bandwidth downlink channel Low-bandwidth uplink channel

Host mobility introduces new issues:

Rerouting of network-layer connections to accommodate mobility Maintaining and adapting QoS guarantees across and during cell transitions What are right semantics for mobile performance guarantees?