195838526
LiB: a cell layout generator
An automatic layout generation system, called LiB, for the library cells used in CMOS ASIC design is presented. LiB takes a transistor-level circuit schematic in SPICE format and outputs a symbolic layout. In LiB, the intra-cell routing runs not only between PMOS and NMOS but also on diffusion islands as well as the two side regions (one between the PMOS diffusion and the power line, and the other between the NMOS diffusion and the ground line). Several heuristic algorithms are proposed to solve the transistor-clustering, -pairing, -chaining, -folding, the chain placement, the routing, and the net assignment problems. Experimental results are presented to show the capability of LiB.<<ETX>>
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>>
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.
16396963
Performance-driven interconnection optimization for microarchitecture synthesis
This paper addresses the interconnection synthesis problem in microarchitecture-level designs. With emphasis on the speed of data movement operations, we propose algorithms that take into consideration the effect of each data-transfer-to-bus binding on the data transfer delay time. The delay time is calculated as a function of both data source load and data carrier (bus) load. By balancing loads among hardware components, the data transfer delay time (hence the total execution time) is shortened. We consider two types of problems: resource-constrained binding and performance-constrained binding. Two integer linear programming (ILP) formulations are derived to optimally solve the problems. In order to speed up the computation, a bipartite weighted matching method for the resource-constrained binding and a greedy merging method for the performance-constrained binding are also proposed. Both the ILP formulation generators and the heuristics have been programmed. Experimental results indicate that the proposed algorithms are indeed very effective in optimizing the performance aspect of the interconnection design. >
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>>
53235373
Performance-optimal clustering with retiming for sequential circuits
11334904
Call Performance for a PCS Network
It is well known that, due to the mobility of a portable and limited channel availability, calls of portables may not be completed due to being blocked or terminated during the call initiation or the handover process. The characteristics of the call-completion and call-holding times for both a complete call and an incomplete call are of critical importance for establishing the actual billing process in the PCS network. We derive the call-completion probability (hence, call-dropping probability) and the effective call-holding time distributions for complete/incomplete calls with a general cell-residence time and a general call-holding time are analyzed, and general computable formulas are obtained. We show that when call-holding times are Erlang distributed, easy-to-compute formulas for the probability of a call completion and the expected effective call-holding times for both a complete call and an incomplete call can be derived.
11629666
Strongly Consistent Access Algorithms for Wireless Data Networks
In wireless data networks such as the WAP systems, the cached data may be time-sensitive and strong consistency must be maintained (i.e., the data presented to the user at the WAP handset must be the same as that in the origin server). In this paper, we study the cached data access algorithms in such systems. Two caching algorithms are investigated. In Algorithm I, Pull-Each-Read, whenever a data access occurs, the client always asks the server whether the cached entry in the client is valid or not. In Algorithm II, Callback, the server always invalidates the cached entry in the client whenever an update occurs. Analytic models are proposed to evaluate the performance of these algorithms. Our studies show that Algorithm II outperforms Algorithm I if the data access rate is high and the access pattern is irregular. We also design an adaptive mechanism to effectively switch between the two algorithms to take advantages of both algorithms. We also apply the single-level cached data access algorithms for the multi-level cache hierarchy. Our study indicates that with appropriate arrangement, strongly consistent cached data access for wireless Internet (such as WAP) can be efficiently supported.
7180014
A software architecture for GPRS session management
General packet radio service (GPRS) provides efficient access to the integrated services Internet from wireless networks. When the GPRS-attached mobile station attempts to send or receive data, a packet data protocol (PDP) context shall be established. The GPRS session management (SM) supports the PDP context handling, which consists of PDP context activation, deactivation, and modification procedures. In this paper, we propose an SM software architecture for the serving GPRS support node. Our design goals are to achieve compatibility, modularity, and flexibility. More importantly, our approach can accommodate the design of the SM software architecture for third-generation wireless networks. Copyright © 2001 John Wiley & Sons, Ltd.
206549585
vGPRS: a mechanism for voice over GPRS
This paper proposes vGPRS, a voice over IP (VoIP) mechanism for a general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, both standard GSM and GPRS mobile stations can be used to receive vGPRS service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities.
11056764
Integrating multi-agent negotiation to resolve constraints in fulfilling supply chain orders
Abstract As the order fulfillment process (OFP) in supply chains shifts to outsourcing paradigm, the OFP performance relies on the coordination among supply chain partners to reach executable and effective plans. The coordination of OFP among supply chain partners can be viewed as a distributed constraint satisfaction problem (DCSP). This study adds the multi-agent negotiation mechanism to enhance the existing methods to solve the DCSP, and then evaluates the integrated system’s performance through experimentation on the OFP in the context of the metal industry. The experimental results show that the integrated system outperforms the existing distributed constraint satisfaction algorithms in various demand patterns.