## 2 Background and Related Work on Routing in WMN-Based NAN
### Routing in WMN-Based NAN
The authors in [18; 19] considered the use of HWMP in an SG deployment by reducing the broadcast storm caused by Address Resolution Protocol (ARP) and utilizing the air cost metric (failure rate of each node calculated by the MAC re-transmission count of each packet) as a performance metric. The proposed method gives more priority to re-transmission of small packets, as they are likely to have fewer bit errors. As a consequence, the protocol becomes more adapted for the NAN domain and improves reliability for the applications that are part of the SG architecture. Though these modifications have improved reliability in SG NAN to a certain extent, they do not guarantee QoS for targeted application traffic types. Furthermore, these protocols mostly utilize the Extended Transmission Count (ETX) as their link metric, which is deficient in certain aspects while calculating paths to a destination. Efforts have been made to enhance QoS features in 802.11 standards through the introduction of 802.11e standards; they are known to be suitable for only single hop communication. This article proposes to improve the OLSR routing protocol using multiple metrics to prioritise the application traffic, as well as to improve the reliability in NAN. There have been numerous QoS-based routing protocols proposed for multi-media applications; some of the routing protocols related to our proposal, that can also be used in the context of NAN, include the following:  
* The QUality Of service RoUting in wireless Mesh networks (QUORUM) proposed in [20] integrates an end-to-end packet delay estimation mechanism with stability-aware routing policies, which allows it to accurately follow QoS requirements of streaming media, such as VOIP, while also minimising the misbehaviour of selfish nodes. The routing protocol provides QoS guarantees to media applications based on metrics of minimum bandwidth and maximum end-to-end delay. * The Hybrid QoS-based Routing Protocol for Wireless Mesh Environment (HQMR) proposed by [PERSON] et al. [21] presented a QoS-based routing protocol that ensures forwarding real-time and streaming applications with QoS guarantee in a mesh wireless environment. This was achieved through the development of a clustering algorithm to enhance scalability issues within the mesh infrastructure and the use of two routing sub-protocols. The sub-protocols consist of a reactive routing protocol for intra-infrastructure communications and a proactive QoS-based multi-tree routing protocol for communications with external networks. * The Mesh Admission control and QoS Routing with Interference Awareness (MARIA) routing scheme was proposed in [4]. MARIA uses a conflict graph to model both inter- and intra-flow interference in wireless networks. An on-demand routing scheme that explicitly incorporates the interference model in the route discovery process is implemented to direct routing message propagations and avoid paths with severe interference. Implementing cross-layer QoS guarantees in NAN-based WMN using the techniques presented in the aforementioned routing schemes can improve reliability across multiple smart meter nodes equipped with the IEEE 802.11 radio in an SG NAN.