195838317
Data path allocation based on bipartite weighted matching
Proposes a graph-theoretic approach for the data path allocation problem. The problem is decomposed into three subproblems: (1) register allocation, (2) operation assignment, and (3) connection allocation. The first two subproblems are modeled as two bipartite weighted matching problems and solved using the Hungarian method. The third subproblem is solved using a greedy method. It is shown that, by taking the other into consideration while solving one, equally satisfactory results can be obtained, regardless of the order in which (1) and (2) are performed. Two programs, LYRA and ARYL, are implemented which solve the subtasks in different orders. For register allocation, the approach is the first one to guarantee minimal use of registers while being able to take the interconnection cost into account. This research has demonstrated that the bipartite weighted matching algorithm is indeed a good solution for the data path allocation problem.<<ETX>>
53235373
Performance-optimal clustering with retiming for sequential circuits
6763648
An effective methodology for functional pipelining
We address the problem of given a loop behavior, a target initiation interval and resource constraints, scheduling a loop in a pipelined fashion such that the iteration time (turn-around time) is minimized. The iteration time is an important quality measure of a data path design because of its direct correlationship with both the storage and the control costs. Our scheduler starts with performing an As Soon As Possible Pipelined (ASAPp) scheduling without regard to the resource constraint. It then resolves the resource constraint violations, if there are any, by repeatedly rescheduling some operations.
16940967
A fast transistor-chaining algorithm for CMOS cell layout
A fast algorithm is proposed for the transistor-chaining problem in CMOS functional cell layout based on the layout style of T. Uehara and W.M. van Cleemput (1981). The algorithm takes a transistor-level circuit schematic and outputs a minimum set of transistor chains. Possible diffusion abutments between the transistor pairs are modeled as a bipartite graph. A depth-first search algorithm is used to search for the optimal chaining. Theorems on the set of branches that needs to be explored at each node of the search tree are derived. A theoretical lower bound on the size of the chain set is also derived. This bound enables one to prune the search tree efficiently. The algorithm has been implemented and tested and is able to find optimal solutions almost instantly for all the cases from the literature that were examined. >
195837942
Optimum and heuristic data path scheduling under resource constraints
An integer linear programming model for the scheduling problem in high-level synthesis under resource constraints is presented. The following applications are considered: multicycle operations with nonpipelined or pipelined function units: mutually exclusive operations: functional pipelining: loop-folding; and scheduling under bus constraint. Besides the model, a new technique, called zone scheduling (ZS), is proposed to solve large-size problems. ZS partitions the distribution graph into several zones and sequentially solves the problems contained. A novel feature of this technique is that it schedules more than one control step at a time, allowing a more global view of a scheduling problem to be taken.<<ETX>>
27186635
Register minimization beyond sharing among variables
Traditionally, it is assumed that every variable in the input HDL (hardware description language) behavioral description needs to be held in a register; a register can be shared by multiple variables if they have mutually disjointed lifetime intervals. This approach has been shown effective for signal-flow-like computations such as various DSP algorithms. However, the same is not true for the synthesis of control-dominated circuits, which usually have variables of different bit-width as well as very long lifetime. To go beyond register minimization by lifetime-analysis-based sharing, we propose holding some variables in the state registers, some signal nets, some unclocked sequential networks or a combination of above. We identify the conditions in which the substitution is feasible. We have implemented the proposed method in a software program called VReg. Experimental results have demonstrated that VReg minimizes the number of registers more effectively than the lifetime-analysis-based approach does. Better register area minimization also generally leads to faster designs.
3227227
Dynamic Resource Assignment Strategies for PCS Data Services
For high speed mobile communication applications, the data rate can be increased by using multiple channels (or time slots) instead of a single channel (or time slot). To reduce the high blocking rate of multiple channels assignment, flexible resource allocation strategies are exercised. This paper proposes a generic Mobile Switching Center (MSC) resource allocation algorithm called MRA algorithm for Personal Communications Services (PCS) data services. The algorithm may combine with any base station resource allocation algorithms proposed in our previous study. A simulation model is proposed to investigate the performance of these algorithms. We define satisfaction indication SI to measure the performance of the resource allocation. SI indicates the customer's satisfaction about the call connection, it can also be used by the service provider as a charge indication.
205212938
General Packet Radio Service (GPRS): architecture, interfaces, and deployment
This article provides an overview of General Packet Radio Service (GPRS). GPRS reuses the existing GSM infrastructure to provide end-to-end packet-switched services. Benefits of GPRS include efficient radio usage, fast set-up/access time and high bandwidth with multiple timeslots. GPRS also provides a smooth path for GSM evolution to the third generation mobile network. Specifically, a third generation network can continue to utilize the GPRS IP backbone network. We describe the GPRS network nodes and the interfaces among these nodes. Deployment issues for GPRS are also elaborated. Copyright 2001 John Wiley & Sons, Ltd.
12722290
A survey and measurement-based comparison of bandwidth management techniques
This article gives a brief tutorial for bandwidth management systems; a survey of the techniques used by eight real-world systems, such as class-based queuing (CBQ), per-flow queuing (PFQ), random early detection (RED), and TCP rate control (TCR); a compact testbed with a set of methodologies to differentiate the employed techniques; and a detailed black-box evaluation. The tutorial describes the needs for the three types of policy rules: class-based bandwidth limitation, session-bandwidth guarantee, and inter/intra-class bandwidth borrowing. The survey portion investigates how the eight chosen commercial/open-source real systems enforce the three policy types. To evaluate the techniques, the designed testbed emulates real-life Internet conditions, such as many simultaneous sessions from different IPs/ports, controllable wide area network (WAN) delay and packet loss rate for each session, and different TCP source implementations. The performance metrics include accuracy of bandwidth management, fairness among sessions, robustness under Internet packet losses and different operating systems, inter/intra-class bandwidth borrowing, and voice over IP (VoIP) quality. The black-box test results demonstrate that (1) only the combination of CBQ+PFQ+TCR can solve the most difficult scenario (multiple sessions competing for the narrow 20kb/s class); (2) the TCR approach may degrade the goodput, fairness, and compatibility even under slight packet loss rates (0.5 percent); (3) without PFQ, TCR and RED have limited ability to isolate the sessions (especially for RED); (4) the G.729 VoIP quality over a 125kb/s access link becomes good only after exercising MSS-clamping to shrink the packet size of the background traffic down to 256 byte.
26702573
Evolution and Evaluation of Internet Content Delivery
Discover the methods for content delivery and distribution of Web-based media in the Web 2.0 world. The concept of Web caches has existed as long as the Web and evolved from storage of frequently accessed files on an individual's personal computer or proxy server to Internet-based Web cache servers provided by companies as a paid subscription service for content providers. As multimedia has become more prevalent on the Web, content delivery networks (CDNs) have become a critical component of the Internet and an enabler of Web 2.0 applications like IPTV, mobile Web and TV devices, and content-rich Web databases such as Wikimedia.
26216894
Equal resource sharing scheduling for PCS data services
For high speed mobile communication applications, the data rate can be increased by using multiple channels (or time slots) instead of one channel. To reduce the high blocking rate of multiple channels assignment, flexible resource allocation strategies have been proposed. This paper proposes the Equal Resource Sharing Allocation scheme (ERSA scheme) for flexible resource allocation. The ERSA scheme dynamically averages the allocated resource to the call requests based on the number of calls in a base station. The scheme accommodates the maximum number of requests while providing acceptable quality to the admitted requests. We developed an analytic model to investigate the performance of ERSA, and conducted simulation experiments to validate the analytic model. We define satisfaction indication SI as the performance measurement of the resource allocation algorithm. The experiment results indicate that the ERSA scheme outperforms other resource allocation algorithms proposed in our previous study.