1437746
On the skew-bounded minimum-buffer routing tree problem
Bounding the load capacitance at gate outputs is a standard element in today's electrical correctness methodologies for high-speed digital very large scale integration design. Bounds on load caps improve coupling-noise immunity, reduce degradation of signal transition edges, and reduce delay uncertainty due to coupling noise (Kahng et al. 1998). For clock and test distribution, an additional design requirement is bounding the buffer skew, i.e., the difference between the maximum and the minimum number of buffers over all of the source-to-sink paths in the routing tree, since buffer skew is one of the main factors affecting delay skew (Tellez and Sarrafzadeh 1997). In this paper, we consider algorithms for buffering a given tree with the minimum number of buffers under given load cap and buffer skew constraints. We show that the greedy algorithm proposed by Tellez and Sarrafzadeh is suboptimal for nonzero buffer-skew bounds and give examples showing that no bottom-up greedy algorithm can achieve optimality. The main contribution of the paper is an optimal dynamic programming algorithm for the problem. Experiments on test cases extracted from recent industrial designs show that the dynamic programming algorithm has practical running time and saves up to 37.5% of the buffers inserted by Tellez and Sarrafzadeh's algorithm.
6291223
Interconnect implications of growth-based structural models for VLSI circuits
Power-law scaling phenomena that govern VLSI circuits have for several decades formed the foundation of VLSI interconnect estimation.   This research investigates possible alternative power-law phenomena in VLSI circuits.   In particular, we develop new<italic>random growth</italic>models and assess their implications for VLSI interconnect structure.   We assess our models' predictions for<italic>fanout</italic>,<italic>crossing edge</italic>, and<italic>terminal</italic>scaling using test data from 21 industry standard-cell designs with up to 283K cells.   Our work demonstrates the possibility of non-Rent based, yet equally plausible and well-fitting, structural models for VLSI circuits and their interconnections.
53249400
Non-tree routing for reliability and yield improvement
We propose to introduce redundant interconnects for manufacturing yield and reliability improvement. By introducing redundant interconnects, the potential for open faults is reduced at the cost of increased potential for short faults; overall, manufacturing yield and fault tolerance can be improved. We focus on a post-processing, tree augmentation approach which can be easily integrated in current physical design flows. Experiments on randomly generated and industry testcases show that our greedy augmentation method achieves significant increase in reliability (as measured by the percentage of biconnected tree edges) with very small increase in wirelength. SPICE simulations imply that non-tree routing has smaller delay variation due to process variability.
5760901
Statistical gate delay calculation with crosstalk alignment consideration
We study gate delay variation caused by crosstalk aggressor alignment, i.e., difference of signal arrival times in coupled neighboring interconnects. This effect is as significant as multiple-input switching on gate delay variation [2]. We establish a functional relationship between driver gate delay and crosstalk alignment by deterministic circuit simulation, and derive closed form formulas for statistical distributions of driver gate delay and output signal arrival time.Our proposed method can be smoothly integrated into a static timing analyzer, which runtime is dominated by sampling deterministic delay calculation, while probabilistic computation and updating take constant time. Our experimental results on 70nm technology global interconnect structures and 130nm technology industry designs show respectively 159:4% and 147:4% differences in mean and standard deviation of gate delay without crosstalk aggressor alignment consideration, while our method gives within 2:57% and 3:86% offset in gate output signal arrival time mean and standard deviation, respectively.
14957159
Utility-Based Bandwidth Allocation for Triple-Play Services
It is expected that, in near future, the multi-class traffic previously in public switched telephone network (PSTN), cable television network and IP network will be multiplexed at backbone and carried by the converged next-generation network (NGN). A pragmatic challenge in facilitating NGN is how to schedule traffic and allocate bandwidth among the triple-play services, namely voice (VoIP), video (IPTV) and data. Different from traditional strict-priority based scheduling intensively used in industry, in this paper, we try to discuss this issue from the objective of network utility maximization (NUM). We first investigate the characteristics of most existing traffic classes and explicitly formulate their utilities to be the function of occupied bandwidth. After that, a novel scheduling scheme to achieve NUM is derived using Lagrange method with KKT conditions. Numerical results under two network scenarios are calculated. Both of them reveal the unique nature of this scheduling, compared with strict-priority scheduling, still highest priority is provided for VoIP traffic, however, no strict priority should be given to IPTV traffic since it will conflict with NUM objective. We hope our results will shed lights on the evolvement towards the converged network
40457509
Temporal segmentation of video using frame and histogram space
Two algorithms are presented for the detection of gradual transitions in video sequences. The first is a dissolve detection algorithm utilizing certain properties of a dissolve's trajectory in image-space. It is implemented both as a simple threshold-based detector, and as a parametric detector by modeling the error properties of the extracted statistics. The second is an algorithm to detect a wide variety of wipes based on image histogram characteristics during such transitions. Both algorithms operate in the compressed domain, requiring only partial decoding of the compressed video stream. Experiments show the algorithms perform as well as-and in some cases, better than-full-frame methods, on a wide variety of gradual transitions, and can operate significantly faster than real-time.
2458786
High Performance Embedded Route Lookup Coprocessor for Network Processors
Embedded Route Lookup Coprocessors (RLCs) are attractive for their potential in building high-performance Network Processors. But compared with conventional lookup schemes, it always imposes more severe restrictions on table size and power consumption, which poses challenge in the state of art. In this paper, we propose a novel lookup mechanism, Compounded CAM with Optimized Bitmap Compression (CCAM-OBC), which employs different lookup methods for prefixes of different length ranges, so as to combine the benefits of CAMs and bitmap compressed tries. With this scheme, table size, power consumption and update complexity are all well optimized while very high lookup throughput is achieved, which makes it a perfect solution to embedded RLC. For a real-life 130K-prefix route table, the implemented prototype performs more than 100 Million Packets Per Second (MPPS) with only 24KB TCAM, 48KB BCAM and 251KB SRAM. Furthermore, each update needs only 2 memory accesses averagely.
5712150
Preemptive Packet-Mode Scheduling to Improve TCP Performance
Recent Internet traffic measurements show that 60% of the total packets are short packets, which include TCP acknowledgment and control segments. These short packets make a great impact on the performance of TCP. Unfortunately, short packets suffer from large delay due to serving long data packets in switches running in the packet mode, i.e. a packet is switched in its entirety. To optimize TCP performance, we apply a cross-layer approach to the design of switching architectures and scheduling algorithms. Specifically, we propose a preemptive packet-mode scheduling architecture and an algorithm called preemptive short packets first (P-SPF). Analysis and simulation results demonstrate that compared to existing packet-mode schedulers, P-SPF significantly reduces the waiting time for short packets while achieving a high overall throughput when the traffic load is heavy. Moreover, with a relatively low speedup, P-SPF performs better than existing packet-mode schedulers under any traffic load.
1001399
DS-PPS: A Practical Framework to Guarantee Differentiated QoS in Terabit Routers with Parallel Packet Switch
Parallel Packet Switch (PPS) is used intensively in today's terabit router to construct the switching fabric. Basic PPS equally deals with all of the traffic in order to achieve uniform load-balancing and high throughput, but it fails to support differentiated QoS. With the recent blooming of delay- sensitive Internet traffic, such as the peer-to-peer live streaming and IPTV, differentiated QoS is becoming an urgent demand. In this paper, we propose a novel and practical framework, the Differentiated Service Parallel Packet Switch (DS-PPS), which supports three fundamental QoS features: guaranteed-delay (GD), guaranteed-bandwidth (GB) and best-effort (BE). By adaptively adjusting the number of switching planes offered to each QoS class, DS-PPS precisely controls the delay bounds of GD traffic and the drop precedence of GB traffic. We evaluate DS-PPS by extensive theoretical analyses and comprehensive simulations. Experimental results on a prototype implementation of the framework show that DS-PPS outperforms the basic PPS in three main aspects. First, the average delay of TCP short packet under full load is reduced by more than 94%. Second, the average delay of real-time traffic under full load is reduced by more than 82%. And third, the GB traffic of low drop precedence is guaranteed of nearly three times the throughput of high drop precedence at the hotspots. Significantly, our proposed DS-PPS framework is universal and scalable to support various kinds of emerging QoS-sensitive applications in multi-service terabit routers without any extra overhead.