Asynchronous quasi-delay-insensitive (QDI) NoCs have several advantages over their clocked counterparts. Virtual channel (VC) is the most utilized flow control method in asynchronous routers but spatial division multiplexing (SDM) achieves better throughput performance for best-effort traffic than VC. A novel asynchronous SDM router architecture is presented. Area and latency models are provided to analyse the network performance of all router architectures including wormhole, virtual channel and SDM. Performance comparisons have been made with different configurations of payload size, communication distance, buffer size, port bandwidth, network size and number of VCs/virtual circuits. Compared with VC, SDM achieves higher throughput with lower area overhead. © 2011 Elsevier B.V. All rights reserved.