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

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 • O T I F S • R C A E V A L I I N F O U • R L E E L I G T H T N H T H I E R B E A T E • • • 1 8 • 8 6 Hitachi-Tenet Meeting 10 November 1993 Providing Network Video Service to Mobile Hosts Page 1 of 16

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 Providing Network Video Service to Mobile Hosts Page 2 of 16

Future Computing Environment Backbone Internetwork 100 Mbps - 1 Gbps VIDEO SERVER BASE INFORMATION STATIONS SERVERS Compressed Video Personal Workstations Portable Multimedia Terminals Providing Network Video Service to Mobile Hosts Page 3 of 16

InfoPad Overview Integrated Pen Input Pad/ Project Focus Flat Panel Display Integrate communication and computation Minimize power consumption Antenna Multimedia Terminal Microphone Text and graphics RF Transceiver Downlink video Battery Speech input/output Packetizer/ Error Correction Pen input Speaker Video Decompression/ Display Driver Speech Codec Providing Network Video Service to Mobile Hosts Page 4 of 16

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 Providing Network Video Service to Mobile Hosts Page 5 of 16

High Throughput from Disk Arrays Array Controller String String String Controller Controller Controller High-bandwidth transfers from multiple disks in parallel Concurrent access by independent users Providing Network Video Service to Mobile Hosts Page 6 of 16

Multi-Resolution Support for Heterogeneity Multiple resolutions of video data stored on server Data provided closely matches requested QoS parameters 90 Missed Retrieval Deadlines 80 Single Resolution 70 Multiple Resolutions 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 Number of Users Providing Network Video Service to Mobile Hosts Page 7 of 16

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 Providing Network Video Service to Mobile Hosts Page 8 of 16

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? Video Server Switch Room-sized Base Station Wireless Network Cell Providing Network Video Service to Mobile Hosts Page 9 of 16

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” Providing Network Video Service to Mobile Hosts Page 10 of 16

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 Providing Network Video Service to Mobile Hosts Page 11 of 16

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? Providing Network Video Service to Mobile Hosts Page 12 of 16

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 Providing Network Video Service to Mobile Hosts Page 13 of 16

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 Providing Network Video Service to Mobile Hosts Page 14 of 16

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 Providing Network Video Service to Mobile Hosts Page 15 of 16

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? Providing Network Video Service to Mobile Hosts Page 16 of 16