Client-controlled QoS Management in Networked Virtual Environments Patrick Monsieurs, Maarten Wijnants, Wim Lamotte Expertise Center for Digital Media Limburgs Universitair Centrum, Belgium

Overview Introduction Introduction Related Work Related Work Network Intelligence Architecture Network Intelligence Architecture Distribution of Available Bandwidth Distribution of Available Bandwidth Experimental Results Experimental Results Conclusions and Future Work Conclusions and Future Work

Introduction Multimedia streams consume large amounts of bandwidth Multimedia streams consume large amounts of bandwidth  Networked multimedia applications do not scale well with large amounts of users that transmit multimedia content  Networked multimedia applications do not scale well with large amounts of users that transmit multimedia content  Reduce downstream bandwidth usage while maintaining QoE  Reduce downstream bandwidth usage while maintaining QoE

NVE Application

Related Work Reducing sender’s quality Reducing sender’s quality Spatial subdivision Spatial subdivision Quality selection Quality selection

Reducing Sender’s Quality Receivers notify senders when downstream capacity is exceeded Receivers notify senders when downstream capacity is exceeded Senders reduce quality of stream to reduce bandwidth Senders reduce quality of stream to reduce bandwidth  Bandwidth and quality of all receivers of the stream is reduced  Bandwidth and quality of all receivers of the stream is reduced

Spatial Subdivision Users in Networked Virtual Environments have a position in the environment Users in Networked Virtual Environments have a position in the environment  The environment can be subdivided in spatial regions  The environment can be subdivided in spatial regions Each user is part of a single region and is only aware of users in nearby regions Each user is part of a single region and is only aware of users in nearby regions Associate a multicast address to each region Associate a multicast address to each region Join or leave multicast addresses to reduce or increase bandwidth usage Join or leave multicast addresses to reduce or increase bandwidth usage

Spatial Subdivision Player A Position Player B Position Player A AOI Player B AOI

Quality Selection Spatial subdivision Spatial subdivision Senders transmit several qualities of streams Senders transmit several qualities of streams Each quality in a region is associated with a multicast address Each quality in a region is associated with a multicast address Receivers select one quality for each nearby region Receivers select one quality for each nearby region Quality determined by distance and available bandwidth Quality determined by distance and available bandwidth

Quality Selection High Quality Medium Quality Low Quality

Per-stream Quality Selection Receivers select the quality of every multimedia stream Receivers select the quality of every multimedia stream Selection based on interest manager of client application Selection based on interest manager of client application Streams must be blocked or received inside the network before reaching the receiver Streams must be blocked or received inside the network before reaching the receiver  Use intelligent proxies inside the network near receivers  Use intelligent proxies inside the network near receivers

Network Intelligence Architecture: Proxies Intelligent proxies are placed in the network near clients Intelligent proxies are placed in the network near clients Intelligent proxies can transcode network streams Intelligent proxies can transcode network streams Reduces or blocks network streams when more bandwidth is requested then available Reduces or blocks network streams when more bandwidth is requested then available

Network Intelligence Architecture: Proxies Bandwidth of streams is reduced based on the importance of each stream and consumed bandwidth Bandwidth of streams is reduced based on the importance of each stream and consumed bandwidth Importance of streams is application specific and is determined by the client application (e.g.. Nearby avatars’ audio streams are more important) Importance of streams is application specific and is determined by the client application (e.g.. Nearby avatars’ audio streams are more important)

Network Intelligence Architecture: Clients Clients have network intelligence layer between transport and application layer Clients have network intelligence layer between transport and application layer Separates application logic (such as interest management) from networking logic (such as bandwidth consumption) Separates application logic (such as interest management) from networking logic (such as bandwidth consumption)

Network Intelligence Architecture

Intelligent Proxy Content-based “transcoders” (block/pass, lower quality, validation, …) Content-based “transcoders” (block/pass, lower quality, validation, …) Located near end-users (eg. DSLAM)  complexity of network management located at edge of network Located near end-users (eg. DSLAM)  complexity of network management located at edge of network Measures bandwidth of managed streams and available bandwidth of link to client Measures bandwidth of managed streams and available bandwidth of link to client When available bandwidth to a client is exceeded, determines which streams to block or transcode When available bandwidth to a client is exceeded, determines which streams to block or transcode

Network Intelligence Layer Replaces standard networking operations Replaces standard networking operations Provides interface with client’s interest manager, which periodically requests the importance of the managed network streams Provides interface with client’s interest manager, which periodically requests the importance of the managed network streams Communicates with intelligent proxies in the network Communicates with intelligent proxies in the network Separates application logic from networking Separates application logic from networking Associates correct transcoder to network stream (type of content is specified on creation of the socket) Associates correct transcoder to network stream (type of content is specified on creation of the socket)

Communication Between Proxy and Network Intelligence Layer Admission control: specify which streams must be managed (filter by destination port on proxy) Admission control: specify which streams must be managed (filter by destination port on proxy) Creation of a stream hierarchy (next slide) Creation of a stream hierarchy (next slide) Communicating importance of streams Communicating importance of streams Multicast tunneling: NI layer monitors which multicast addresses are joined by clients Multicast tunneling: NI layer monitors which multicast addresses are joined by clients

Distribution of Available Bandwidth Hierarchy of available streams Hierarchy of available streams Relative QoS Relative QoS Components: Components: –Priority –Mutex –Weighted collection Priority Weight Mutex Weight Mutex Position updates 3D models Audio data Video data wiwi wiwi wiwi wiwi wiwi wiwi wiwi

Distribution of Weighted Collections Stream s i has weight w i between 0 and 1 Stream s i has weight w i between 0 and 1 Stream s i consumes bandwidth m i Stream s i consumes bandwidth m i Total bandwidth M =  i m i Total bandwidth M =  i m i Reduce bandwidth if M > available bandwidth B Reduce bandwidth if M > available bandwidth B h(i, b) := highest transcoded bandwidth of stream s i that is less than bandwidth b h(i, b) := highest transcoded bandwidth of stream s i that is less than bandwidth b Weighted bandwidth W =  i w i m i Weighted bandwidth W =  i w i m i

Distribution of Weighted Collections Initial estimate t (i) for stream s i : t (i) = h(i, w i m i B/W) Initial estimate t (i) for stream s i : t (i) = h(i, w i m i B/W)  i t (i)  B  i t (i)  B Remaining bandwidth R 0 = B -  i t (i) Remaining bandwidth R 0 = B -  i t (i) Distribute remaining bandwidth: Distribute remaining bandwidth: –Assume streams ordered by w i, w 0 highest: –Target bandwidth T(i) = h(i, t (i) + R i ) where R i = R i-1 – (T(i-1) – t (i-1)) for i > 0

Experimental Setup Intelligent client Intelligent proxy Network Clients

Experiment 1 Maximum available bandwidth is reduced over time Maximum available bandwidth is reduced over time Clients remain stationary in the world Clients remain stationary in the world Nearby clients have higher weights Nearby clients have higher weights

Experiment 1

Experiment 2 Fixed maximum available bandwidth Fixed maximum available bandwidth Bandwidth is not sufficient to transmit all video streams at highest quality Bandwidth is not sufficient to transmit all video streams at highest quality First, client 3 moves away from the intelligent client (reducing its weight), and later returns quickly First, client 3 moves away from the intelligent client (reducing its weight), and later returns quickly

Experiment 2

Conclusions Bandwidth of managed streams is adapted to maximum available bandwidth Bandwidth of managed streams is adapted to maximum available bandwidth Distribution of bandwidth is dynamic, based on the client’s interest in each stream Distribution of bandwidth is dynamic, based on the client’s interest in each stream Separation of application logic and network logic Separation of application logic and network logic Intelligent proxy architecture is useful for mobile devices such as PDA’s Intelligent proxy architecture is useful for mobile devices such as PDA’s