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.