Low-power network-on-chip for high-performance SoC design
An energy-efficient network-on-chip (NoC) is presented for possible application to high-performance system-on-chip (SoC) design. It incorporates heterogeneous intellectual properties (IPs) such as multiple RISCs and SRAMs, a reconfigurable logic array, an off-chip gateway, and a 1.6-GHz phase-locked loop (PLL). Its hierarchically-star-connected on-chip network provides the integrated IPs, which operate at different clock frequencies, with packet-switched serial-communication infrastructure. Various low-power techniques such as low-swing signaling, partially activated crossbar, serial link coding, and clock frequency scaling are devised, and applied to achieve the power-efficient on-chip communications. The 5 /spl times/5 mm/sup 2/ chip containing all the above features is fabricated by 0.18-/spl mu/m CMOS process and successfully measured and demonstrated on a system evaluation board where multimedia applications run. The fabricated chip can deliver 11.2-GB/s aggregated bandwidth at 1.6-GHz signaling frequency. The chip consumes 160 mW and the on-chip network dissipates less than 51 mW.

title: An arbitration look-ahead scheme for reducing end-to-end latency in networks on chip
abstract: With the increasing complexity of system-on-chips, networks on chip (NoC) using multi-hop switching require low end-to-end latency for QoS guarantees. An arbitration look-ahead scheme is proposed to reduce the end-to-end packet latency in the NoC. Its packet arbitration at each switch is completed a few cycles in advance of the packet arrival. As a result, a packet bypasses the switch without the latency of input queuing and arbitration. This scheme is analyzed on a 4/spl times/4 mesh topology. A maximum 65% and average 26% latency reduction are obtained under random traffic. Latency reduction up to 36% is achieved under multimedia traffic.

title: SILENT: serialized low energy transmission coding for on-chip interconnection networks
abstract: On-chip source-synchronous serial communication has many advantages over multi-bit parallel communication in the aspects of skew, crosstalk area cost, wiring difficulty, and clock synchronization. However, the serial wire tends to dissipate more energy than parallel bus due to the bit multiplexing. We propose a coding method to reduce the transmission energy of the serial communication by minimizing the number of transitions on the serial wire. We demonstrate the significant energy saving in a multimedia application, 3D graphics. We also apply the coding technique to a CMOS SoC implementation which integrates various processing units with packet switched on-chip networks.

title: An interactive video delivery and caching system using video summarization
abstract: With the advance of high-speed network technologies, the availability and popularity of streaming media content over the Internet has grown rapidly in recent years. The delivery and caching of streaming media must be handled in a different fashion than that of traditional non-streaming objects such as HTML or image files, because of its distinct characteristics and user viewing patterns. We propose a novel scheme that provides users with the video summary (a number of key-frame images) before they download the file, and options for them to select the starting playback position. We introduce the content analysis service to achieve these functionalities. The video content analysis performs shot boundary detection, key-frame selection, and face detection and tracking. The results of the processing are a segmented video sequence and an XML-based meta-data describing the video content. We also design a caching system that utilizes our video abstraction and summarization technique. Our integrated video delivery and caching system combines content-aware segmentation, prefix caching, prefetching, and cooperative caching. We describe how our scheme can be applied in three proposed caching architectures.

title: FGS-based video streaming test-bed for MPEG 21 universal multimedia access with digital item adaptation
abstract: It is a challenging problem to stream real-time video over heterogeneous networks with time-varying channel conditions and devices with different capabilities. In this paper, we present an FGS-based unicast video streaming test bed, which is now being considered by the MPEG-4/21 committee as a reference test bed. The proposed system supports resource adaptation delivery of the MPEG-21 DIA scheme which leads to a more strict evaluation methodology according to the MPEG committee specified common test conditions for scalable video coding. It provides easy control of media delivery with duplicable network conditions. To provide the best quality of service for each client, we propose relevant rate control, error protection, and transmission approaches in the content server, network interface, and clients, respectively.

title: NodeWiz: peer-to-peer resource discovery for grids
abstract: Efficient resource discovery based on dynamic attributes such as CPU utilization and available bandwidth is a crucial problem in the deployment of computing grids. Existing solutions are either centralized or unable to answer advanced resource queries (e.g., range queries) efficiently. We present the design of NodeWiz, a grid information service (CIS) that allows multi-attribute range queries to be performed efficiently in a distributed manner. This is obtained by aggregating the directory services of individual organizations in a peer-to-peer information service.

title: UAMAC: Unidirectional-Link Aware MAC Protocol for Heterogeneous Ad Hoc Networks
abstract: In heterogeneous ad hoc networks, high-power nodes could potentially interfere with any on-going transmissions of low-power nodes. In this paper, we propose a unidirectional-link aware MAC protocol (UAMAC) which prevents such an interference problem by reserving the wireless channel of unidirectional high-power node selectively over one-hop. Our preliminary performance results show that the UAMAC works well in these heterogeneous environments with unidirectional links.

title: Backbone construction in selfish wireless networks
abstract: We present a protocol to construct routing backbones in wireless networks composed of selfish participants. Backbones are inherently cooperative, so constructing them in selfish environments is particularly difficult; participants want a backbone to exist (soothers relay their packets) but do not want to join the backbone (so they do not have to relay packets for others).
 We model the wireless backbone as a public good and use impatience as an incentive for cooperation. To determine if and when to donate to this public good, each participant calculates how patient it should be in obtaining the public good. We quantify patience using the Volunteer's Timing Dilemma (VTD), which we extend to general multihop network settings. Using our generalized VTD analysis, each node individually computes as its dominant strategy the amount of time to wait before joining the backbone. We evaluate our protocol using both simulations and an implementation. Our results show that, even though participants in our system deliberately wait before volunteering, a backbone is formed quickly. Further, the quality of the backbone (such as the size and resulting network lifetime) is comparable to that of existing backbone protocols that assume altruistic behavior.