A Cross-Layer Approach for Concurrent Delay and Throughput Assurances in Multihop Wireless Hotspots

Next generation Wireless Local Area Networks (WLAN’s) are likely to require multihop wireless connections between mobile nodes and Internet gateways to achieve high data rates from larger distances. The paper addresses the challenges in concurrently providing a wide range of end-to-end throughput and delay assurances in such mobile multihop WLAN hotspots. The proposed solution is based on the Neighborhood Proportional Delay Differentiation (NPDD) service model. With NPDD, Transmission Control Protocol (TCP) based applications achieve their desired throughputs using a dynamic class selection mechanism. This approach integrates well with the NPDD-based end-to-end delay assurance mechanism proposed earlier. To better model the node mobility in a multihop hotspot in our simulation studies, the Public Hotspot Mobility (PHM) model is proposed. Simulation results show that the proposed solution is better in meeting the desired throughputs and delays as compared with best effort and strict priority approaches. Recent theoretical analyses show that the NPDD model with a continuous range of classes can guarantee convergence to desirable QoS through dynamic class selection. However, the overhead of realizing the continuous class scheduler is high. We propose two continuous NPDD schedulers, the Single Queue Continuous NPDD (SQ-CNPDD) scheduler and the Multiple Queue Continuous NPDD (MQ-CNPDD) scheduler, to realize the continuous NPDD model. With simulations, the performance of SQ-CNPDD and MQ-CNPDD are compared to that of NPDD.Kuang-Ching Wang received the B. S. and M. S. degrees in electrical engineering from the National Taiwan University, Taipei, Taiwan, in 1997 and 1999, and the M. S. and Ph. D. degrees in electrical and computer engineering from the University of Wisconsin, Madison, in 2001 and 2003, respectively. Dr. Wang is currently with the Department of Electrical and Computer Engineering, Clemson University, Clemson, SC, as an Assistant Professor. From 2000 to 2003, he participated in the DARPA Sensor Information Technology (SensIT) Program as the leading developer of its network protocols and collaborative signal processing applications. His research interests include wireless networks, mobile computing, distributed protocols, and embedded systems. Dr. Wang is a member of the IEEE Computer, Communication, and Biomedical Engineering Societies and the Association for Computing Machinery.Parameswaran Ramanathan received the B. Tech degree from the Indian Institute of Technology, Bombay, India, in 1984, and the M. S. E. and Ph. D. degrees from the University of Michigan, Ann Arbor, in 1986 and 1989, respectively. Since 1989, Dr. Ramanathan has been faculty member in the Department of Electrical & Computer Engineering, University of Wisconsin, Madison, where is presently a Full Professor. He leads research projects in the areas of sensor networks and next generation cellular technology. In 1997–98, he took a sabbatical leave to visit research groups at AT&T Laboratories and Telcordia Technologies. Dr. Ramanathan’s research interests include wireless and wireline networking, real-time systems, fault-tolerant computing, and distributed systems. He is presently an Associate Editor for IEEE Transactions on Mobile Computing and Elsevier AdHoc Networks Journal. He served as an Associate Editor for IEEE Transactions on Parallel and Distributed Computing from 1996–1999. He has also served on program committees of conferences such as Mobicom, Mobihoc, International Conferences on Distributed Systems and Networks, Distributed Computing Systems, Fault-tolerant Computing Symposium, Real-time Systems Symposium, Conference on Local Computer Networks, and International Conference on Engineering Complex Computer Systems. He was the Finance and Registration Chair for the Fault-tolerant Computing Symposium (1999). He was the program co-chairman of the Workshop on Sensor Networks and Applications (2003), Broadband Wireless (2004), Workshop on Architectures for Real-time Applications, 1994 and the program vice-chair for the International Workshop on Parallel and Distributed Real-time Systems, 1996. He is a member of Association of Computing Machinery and a senior member of IEEE.This revised version was published online in August 2005 with a corrected cover date.