Abstract

Heterogeneous multihop wireless networks such as wireless mesh networks consist of a set of resource-constrained mobile nodes that want to communicate with each other and a set of fixed relay nodes that are equipped with better resources and help in relaying data to the mobile nodes. Supporting real-time traffic in wireless mesh networks is considered as a challenging problem. In a synchronous or asynchronous slotted environment, the position of reservation slots at every link of an end-to-end path influences the end-to-end delay. The major contributions of this paper are the following: (i) an on-demand QoS routing protocol for asynchronous single channel wireless mesh networks, (ii) three heuristics for the slot allocation and positioning process in such networks, and (iii) the adaptations of slot allocation and positioning strategies for taking advantage of the recovery capacity effect of batteries of the mobile nodes. The heuristics we propose are the Early Fit Reservation (EFR), Minimum Bandwidth Reservation (MBR), and the Position-based Hybrid Reservation (PHR). The EFR heuristic reserves bandwidth at the first available slot on every link on a link-by-link basis in the forward path. The MBR heuristic allocates bandwidth on the links in the increasing order of bandwidth and the PHR heuristic assigns bandwidth for every link at a position which is proportional to its location in the path. Recent studies on chemical battery characteristics show that a pulsed current discharge can extend the battery life compared to a continuous discharge. We have also adapted the basic slot allocation strategies, that are aimed at maximizing system throughput, to take benefit of the pulsed discharge model. The adapted heuristics are designed to provide an extended battery life and hence reduce the number of battery recharges. Simulation studies show that EFR performs better in terms of delay characteristics, whereas PHR and MBR provide better system throughput in terms of call acceptance rate. The adapted heuristics are found to be performing better in terms of the number of deaths of mobile nodes and the average number of path breaks.

Keywords: Asynchronous ad hoc wireless networks; Time sensitive traffic; End-to-end reservation; Reservation slot positioning; Hybrid wireless mesh networks

Article Outline

1. Introduction

1.1. Why an asynchronous environment?

2. Related work

3. Reference protocols and models used in our work

3.1. The RTMAC protocol

3.2. The DSR protocol

3.3. Power management model

4. Our slot allocation framework

4.1. The QoS-DSR Protocol

5. Simulation results

6. Conclusions

References

Vitae