# MBMQA: A Multicriteria-Aware Routing Approach for the IoT 5G Network Based on D2D Communication
## 2 Related Works  
The concept of ad-hoc networks was first introduced in Near-term digital radio (NTDR) in the early 1990s and soon evolved into vast clusters of networks comprised of several hundreds of devices connected together without any relay or intermediate devices. Networks that support such devices are termed the D2D communication-based IoT 5G network, which does not rely on previously deployed infrastructure. Devices on this network are capable of forming connections on their own without the aid of intermediate relays to provide connectivity to devices [24; 25]. The positions of devices in the D2D communication-based IoT 5G network are not defined, while freedom is provided in initial positions. Free movement of the devices is considered a challenge for the designers in order to retain a record of every device position so that the communication can be alive while devices are free to move. Routing protocols are responsible for providing feasible routes to the required destination devices at a given time to ensure that the performance is not compromised and expectations in terms of QoS are met [26; 27; 28; 29]. Throughout the years, scholars have executed various approaches to discover the appropriate routing protocol in terms of fault tolerance, scalability, performance, reliability, improved resource utilization, feature specificity, improved QoS, etc. The ad-hoc network routing is divided into two groups, proactive and reactive, based on the possibility of finding the path before or after a packet is sent to its destination. The proactive routing protocols tend to find all paths beforehand, while the reactive routing protocols are activated merely when a packet is sent to a destination, and only one path is computed to ease the load on the device and maintain the flow of information. Infrastructure-based networks are fixed and deployed in a managed scenario where the administrator can set and implement its policies. Therefore, the proactive type is well-suited for such types of networks. On the other hand, ad-hoc networks tend to rely on the devices to carry out the traffic and provide routing decisions while they are portable, mobile and require less computing power. For this reason, reactive routing protocols are the first choice that has low power consumption since it is self-maintained and can find routes solely when needed for a particular destination. However, reactive routing protocols are designed to find a single path to the destination due to the complexity of the network. In recent years, considerable advancement in processing power has been made, while multiple paths to a single destination could be easily computed. Multiple paths could further improve the network's performance by allowing devices to balance the traffic load from source to destination via multiple links. The number of recent findings are summarized in this section, which focuses on multi-path routing protocols for the D2D communication-based IoT 5G network [30; 31]. In [32], the authors proposed an Energy-Efficient Cloud-Assisted Routing Mechanism (EERM) for Cloud Assisted-Mobile Ad-Hoc Networks (CA-MANETs). The Bellman-Ford algorithm was modified for a fast route recovery mechanism to select an alternate route when link failure occurs among the devices. In this paper, the authors introduced three new functions named Service Scheduling, Information Update and Information Notice for maintaining connections in the CA-MANETs. The EECRM scheme has minimized energy consumption, enhanced routing performance, and extended the lifetime of CA-MANETs. Meanwhile, in [33], the authors introduced an effective energy harvesting-aware routing algorithm (EHARA), in which an energy harvesting mechanism was utilized to investigate the issues of energy efficiency, QoS, network lifetime, and heterogeneity of IoT devices. The proposed routing scheme exploited two cost metrics, such as harvested energy and the residual energy of the device, to select the optimal path for forwarding data packets from the source to the destination devices.