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FOARS: FLUTE based obstacleavoiding rectilinear Steiner tree construction
 In Proc. of ISPD
, 2010
"... Obstacleavoiding rectilinear Steiner minimal tree (OARSMT) construction is becoming one of the most sought after problems in modern design flow. In this paper we present FOARS, an algorithm to route a multiterminal net in the presence of obstacles. FOARS is a top down approach which includes parti ..."
Abstract

Cited by 4 (1 self)
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Obstacleavoiding rectilinear Steiner minimal tree (OARSMT) construction is becoming one of the most sought after problems in modern design flow. In this paper we present FOARS, an algorithm to route a multiterminal net in the presence of obstacles. FOARS is a top down approach which includes partitioning the initial solution into subproblems and using obstacle aware version of Fast Lookup Table based Wirelength Estimation (OAFLUTE) at a lower level to generate an OAST followed by recombining them with some backend refinement. To construct an initial connectivity graph FOARS uses a novel obstacleavoiding spanning graph (OASG) algorithm which is a generalization of Zhou’s spanning graph algorithm without obstacle [1]. FOARS has a run time complexity of O(nlog n). Our experimental results
Practical Approximations of Steiner Trees in Uniform Orientation Metrics
"... The Steiner minimum tree problem, which asks for a minimumlength interconnection of a given set of terminals in the plane, is one of the fundamental problems in Very Large Scale Integration (VLSI) physical design. Although advances in VLSI manufacturing technologies have introduced additional rout ..."
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The Steiner minimum tree problem, which asks for a minimumlength interconnection of a given set of terminals in the plane, is one of the fundamental problems in Very Large Scale Integration (VLSI) physical design. Although advances in VLSI manufacturing technologies have introduced additional routing objectives, minimum length continues to be the primary objective when routing noncritical nets, since the minimumlength
The MST of Symmetric Disk Graphs (in Arbitrary Metric Spaces) is Light ∗
"... Consider an npoint metric space M = (V, δ), and a transmission range assignment r: V → R + that maps each point v ∈ V to the disk of radius r(v) around it. The symmetric disk graph (henceforth, SDG) that corresponds to M and r is the undirected graph over V whose edge set includes an edge (u, v) if ..."
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Consider an npoint metric space M = (V, δ), and a transmission range assignment r: V → R + that maps each point v ∈ V to the disk of radius r(v) around it. The symmetric disk graph (henceforth, SDG) that corresponds to M and r is the undirected graph over V whose edge set includes an edge (u, v) if both r(u) and r(v) are no smaller than δ(u, v). SDGs are often used to model wireless communication networks. AbuAffash, Aschner, Carmi and Katz (SWAT 2010, [1]) showed that for any npoint 2dimensional Euclidean space M, the weight of the MST of every connected SDG for M is O(log n) · w(MST(M)), and that this bound is tight. However, the upper bound proof of [1] relies heavily on basic geometric properties of constantdimensional Euclidean spaces, and does not extend to Euclidean spaces of superconstant dimension. A natural question that arises is whether this surprising upper bound of [1] can be generalized for wider families of metric spaces, such as highdimensional Euclidean spaces. In this paper we generalize the upper bound of AbuAffash et al. [1] for Euclidean spaces of any dimension. Furthermore, our upper bound extends to arbitrary metric spaces and, in particular, it applies to any of the normed spaces ℓp. Specifically, we demonstrate that for any npoint metric space M, the weight of the MST of every connected SDG for M is O(log n) · w(MST(M)).
Rio Design Automation
"... FLUTE [1, 2] is a very fast and accurate rectilinear Steiner minimal tree (RSMT) 1 algorithm particularly suitable for VLSI applications. It is optimal for nets up to degree 9 and is still very accurate for nets up to degree 30. However, for higher degree nets, the original FLUTE algorithm is not ef ..."
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FLUTE [1, 2] is a very fast and accurate rectilinear Steiner minimal tree (RSMT) 1 algorithm particularly suitable for VLSI applications. It is optimal for nets up to degree 9 and is still very accurate for nets up to degree 30. However, for higher degree nets, the original FLUTE algorithm is not effective. In this paper, we present an improvement of FLUTE which is more effective in handling nets with degree tens or more. The main idea is to partition a net according to a spanning tree into small subnets that can be handled effectively by the original FLUTE algorithm. Several novel techniques are proposed to partition a net into small subnets and to merge the Steiner trees for the subnets together. Some improvements of the original FLUTE algorithm, and a scheme to allow users to control the tradeoff between accuracy and runtime are also presented. We show experimentally that the resulting algorithm FLUTE3.0 achieves a much better accuracyruntime tradeoff than the original FLUTE algorithm for degree 30 or more. It produces better quality of result than the wellknown nearoptimal BI1S algorithm [3] in a runtime shorter than the highly scalable BGA algorithm [4]. FLUTE3.0 is also highly scalable. It can route a 3millionpin net in about 25 minutes. 1
ISPD: FOARS: FLUTE Based ObstacleAvoiding Rectilinear Steiner Tree Construction
"... In this paper, we present an algorithm called FOARS for obstacleavoiding rectilinear Steiner minimal tree (OARSMT) construction. FOARS applies a topdown approach which first partitions the set of pins into several subsets uncluttered by obstacles. Then an obstacleavoiding Steiner tree is generat ..."
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In this paper, we present an algorithm called FOARS for obstacleavoiding rectilinear Steiner minimal tree (OARSMT) construction. FOARS applies a topdown approach which first partitions the set of pins into several subsets uncluttered by obstacles. Then an obstacleavoiding Steiner tree is generated for each subset by an obstacle aware version of the rectilinear Steiner minimal tree (RSMT) algorithm FLUTE. Finally, the trees are merged and refined to form the OARSMT. To guide the partitioning of pins, we propose a novel algorithm to construct a linearsized obstacleavoiding spanning graph (OASG) which guarantees to contain a rectilinear minimum spanning tree if there is no obstacle. Experimental results show that FOARS is among the best algorithms in terms of both wirelength and runtime for testcases both with and without obstacles.