A consistent local congestion avoiding strategy for iterative improvement of cross point assignment

Cross point assignment (CPA) is a critical step between global routing and detailed routing. Usually, a CPA algorithm includes two steps:initial CPA and iterative improvement. In this paper, we proposed a consistent local congestion avoiding strategy for CPA iterative improvement based on four congestion lines which describe accurately the local congested area in a congested GRC. The whole strategy consists of three consistent parts: rip up nets crossing congestion lines, re-route (global routing) nets without crossing congestion lines, and avoid crossing congestion line while re-assigning cross points for ripped up nets. By this strategy, we not only avoid local congestion area, but also make fully use of the routing area in congested GRC´s. Experimental results show that our strategy can reduce congested GRC´s effectively and achieve high completion rate in detailed routing.