Streaming video to mobile devices like cellular phones is an important emerging application. However, mobile thin clients have limited capabilities and offer restricted interfaces to the end-user and the Telco infrastructure has significant technical barriers which limit the introduction of new protocols. This paper describes our design of an end-to-end interactive video service. We outline the technological and user-interaction challenges of providing one typical type of interactive controls-time-scale modification (TSM), when streaming compressed audio-video data within the Telco infrastructure in a way that maintains audio-video synchronization and respects the video frame and bit-rate contracts

A mobile streaming media content delivery network can facilitate the access of rich multimedia streams by mobile users on next generation wireless networks. A principal component of this network is the edge servers that cooperate to provide streaming functionalities. This paper describes some of the design requirements for such servers. It then describes the architecture of such a streaming content, a modular design, and an intelligent scheduler for providing better video quality in varying network conditions. Finally, preliminary performance results are shown.

Delivering media to large numbers of mobile users presents challenges due to the stringent requirements of streaming media, mobility, wireless, and scaling to support large numbers of users. This paper presents a mobile streaming media content delivery network (MSM-CDN) designed to overcome these challenges. The MSM-CDN is a network overlay consisting of overlay servers on top of the existing network; these overlay servers are control points that facilitate end-to-end media delivery and mid-network media services. This paper presents an overview of the MSM-CDN system architecture, and describes the testbed prototype that we built based on these architectural principles. The MSM-CDN provides a new platform for media delivery, and we describe a number of research directions related to the MSM-CDN.

With the introduction of the next generation wireless network, mobile devices access increasingly more media-rich content. However, a key factor that prevents a mobile device from accessing multimedia content is that it does not have enough display real estate to render the content that is traditionally created for the desktop web client. Moreover, the wireless network typically has lower bandwidth compared to a wired network of the same time frame. Therefore, a transcoder is needed somewhere in the network to transform multimedia content to the appropriate form factor and bandwidth requirement. This paper introduces an extremely fast transcoder of such kind. Comparing to the previous methods, additional computation is saved while the quality of transcoding is maintained. This saving in computing resources maps into the benefit that more concurrent sessions can be supported on one transcoding device. This scalability is crucial for the wireless network to handle user requests that might be very intensive at times.

Media transcoding can be used to enable mobile devices that have low resolution and low bit-rate capabilities to access content created for stationary, desktop clients with high bandwidth connections. By deploying transcoding servers near the edge of a large network, it becomes possible to support clients with multiple resolutions, while limiting the bandwidth requirements in the core network.

This paper summarizes our research on implementing a compressed memory in computer systems. The basic premise is that the throughput for applications whose working set size does not fit in main memory degrades significantly due to an increase in the number of page faults. Hence we propose compressing memory pages that need to be paged out and storing them in memory. This hides the large latencies associated with a disk access, since the page has to be merely uncompressed when a page fault occurs. Our implementation is in the form of a device driver for Linux. We show results with some applications from the SPEC 2000 CPU benchmark suite and a computing kernel. It is seen that speed-ups ranging from 5% to 250% can be obtained depending on the paging behavior of the application.

Clusters of Symmetrical Multiprocessors (SMPs) have recently become popular as low-cost, high-performance computing solutions. The type of interconnection hardware used in these clusters can become a deciding factor in their overall performance. This paper evaluates the performance of three different communication systems, 10 Mbps Ethernet, 100 Mbps FastEthernet and 155 Mbps ATM, using a multithreaded Distributed Shared Memory system, Strings. The raw performance of each network is first measured using netperf. Ten different applications are then used for performance evaluation, including programs from the SPLASH-2 benchmarks, a medical computing application, and some computational kernels. It is found that half of the programs tested are not significantly affected by changes in the bandwidth. Though the ATM network provides the highest overall bandwidth, the remaining applications show that the increase in latency compared to FastEthernet prevents any performance improvement. On the other hand, applications that require only moderately high bandwidths perform substantially better with FastEthernet.

Introduces Strings, a high-performance distributed shared memory system designed for clusters of symmetrical multiprocessors (SMPs). The distinguishing feature of this system is the use of a fully multithreaded runtime system, written using POSIX threads. Strings also allows multiple application threads to be run on each node in a cluster. Since most modern UNIX systems can multiplex these threads on kernel-level lightweight processes, applications written using Strings can use all the processors in a SMP machine. This paper describes some of the architectural details of the system and analyzes the performance improvements with two example programs and a few benchmark programs from the SPLASH-2 suite.