## 2 Background and Related Work on Routing in WMN-Based NAN
### Routing in WMN-Based NAN  
In WMN, routing protocols are responsible for finding paths whenever a packet is to be sent from a source node to a destination node with the help of intermediate nodes. Therefore, routing protocols for NAN-based WMN must have sufficient capabilities to support QoS routing and the different requirements of target applications. In [11], a performance evaluation and comparison of OLSR and the WMN standard Protocol the HWMP in ns-3 are presented. This paper was used to highlight the use of the OLSR routing protocol in NAN. Since the performance of these applications has to be determined in objective terms against a set of pre-defined QoS attributes, such as delay and packet delivery ratio, in [12], the conference paper \"Multiple Metrics-OLSR in NAN for Advanced Metering Infrastructures\" presented the possibility of using AHP and multiple metrics in OLSR for NAN-based WMN to support QoS for the different application traffic types. This was achieved by presenting a case study to show the application traffic best supported by a link metric type and a demonstration of how the AHP algorithm (Equations (3), (5) and (7)) can be used to map paths calculated by a link metric to an application traffic type. The improvement of this article compared with [11; 12] is that this article presents an implementation of the AHP in ns-2 using a simulation topology that represents a worst case scenario of AMI activities (where all smart meter nodes are transmitting four different application traffic types simultaneously to a data concentrator) in a five by five grid size NAN-based WMN. Equations (3), (5) and (7) are a demonstration of how the AHP is calculated, and they reference the proposed methodology presented in the second conference paper. A number of routing protocols have been modified to improve the reliability of routing in SG NAN. Instead of a detailed survey on routing protocol modification for NAN, we concentrate on the modifications related to our proposal. The Ad hoc On-Demand Routing protocol (AODV) is an on-demand routing protocol in which routes are established upon necessity. In [13], the authors modified the AODV protocol, such that selected nodes were provided with more intelligence, which contributed to lower latency, compared to the original AODV and made it useful for demand response (DR) and electronic vehicle (EV) charging application traffic types. A table-driven AODV, which utilised multiple paths and HAN parameters to improve the reliability of traffic in HAN, is also presented in [14]. Dynamic source routing (DSR) protocol is also an on-demand routing protocol that uses the concept of source routing; it requires a node to maintain a route cache, which contains source routes that are known by all other nodes. The route cache is continually updated as the nodes learn new routes to the source node. It is based on the RFC4728 [15]. In [16], an evaluation of AODV in a grid-based cluster was carried out. The study considered energy consumed in transmit, receive and idle modes, as well as residual battery capacity. Though the results show that AODV has a better consumption of energy than DSR, the residual battery capacity showed similar values for both protocols. Distributed autonomous depth-first routing (DADR) is a proactive distance vector protocol that uses a control mechanism to provide at most k (if available) paths for each destination. In [17], a simulation that involved 2000 smart meters was presented, and the results show that DADR learns new routes in large-scale indoor and outdoor networks with low overheads. The study also revealed that packet latency in a flat mesh network is affected by the several hops that data packets traverse to reach their destination. HWMP is the default routing protocol for IEEE 802.11s WLAN mesh networking. It was developed to allow interoperability between devices from different vendors; HWMP serves as a common path selection protocol for every device that is compliant with the IEEE 802.11s standard.