SINR-based routing in multi-hop wireless networks to improve VoIP applications support

The next generation of wireless networks is expected to support a wide range of real-time multimedia applications with stringent quality of service (QoS) requirements. In this paper, we study the performance of 802.11b wireless multi-hop networks carrying Voice over IP (VoIP) calls. We compare the performance of the standard proactive ad hoc routing protocol, OLSR, which makes use of the hop count as routing metric, with two modified versions: SP-OLSR (Strongest Path OLSR) and S2P-OLSR (Shortest Strong Path OLSR). Both of them consider the Signal to Interference and Noise Ratio (SINR) to build a reliable topology graph. The cross-layer aspect is employed to compute and push the SINR values from the physical layer to the routing protocol. We implemented the proposed protocols in the Qualnet simulator and performed extensive simulations using a proper traffic model tailored for VoIP traffic in such an environment. Obtained results indicate that the quality of VoIP applications improves significantly using SP-OLSR and S2P-OLSR compared to the standard OLSR, and that S2P-OLSR offers the same performances as SP-OLSR with a lower routing overhead cost.