# An Improved Routing Approach for Enhancing QoS Performance for D2D Communication in B5G Networks
## 2 Related Works  
This section discusses recent works on routing approaches in wireless networks involving network stability, energy resource, link quality, and device fairness. D2D communication routing in 5G networks has been studied by several authors [19; 20; 21; 22; 23; 24], in which some initiatives have been found to be sufficient for the development of D2D communication in IoT-based 5G networks. Optimized link-state routing (OLSR) is a well-known routing protocol widely used in wireless networks. All of the network nodes have primary routing information through periodical topological message exchange, such as HELLO and topology control (TC) messages [25]. The network nodes also have network routing information, which is used when needed. Maintaining the network routing information via the exchange of topological messages in the network increases the flooding of control overhead messages, congestion, and energy consumption, resulting in network performance degradation. In order to minimize the flooding of control overhead messages in the network, OLSR exploits an efficient multi-point relay (MPR) mechanism in the route selection process, which is the main function of the OLSR protocol. OLSR has been modified and enhanced over time by several researchers since its inception. Other than that, ref. [26] studied an efficient mechanism for the selection of MPRs, which is aimed at improving network performance by minimizing the number of signaling overheads through a simple modification in the OLSR scheme. A new degree of database information from a neighbor's device is employed for the selection of MPRs, in which the exchange of topological message is extended to three hops. The proposed mechanism reduces the control signaling overhead in the network compared to the OLSR protocol. Another work carried out in [27] introduced parallel disjointed multipath-based OLSR (DMP_EOLSR) algorithm for wireless networks. The proposed protocol utilizes the living time of nodes and living time of links based on the nodes' energy consumption and movement mode. Meanwhile, an iterative algorithm based on a modified [PERSON]'s algorithm is employed to discover several node-disjointed or link-disjointed paths in the multi-path selection and recovery process. The simulation  
Figure 2: Multiple routes between source and destination devices in a D2D communication scenario. results prove that the DMP_EOLSR improves network stability and transmission efficiency by mitigating the number of interrupted network nodes and links. In [28], a traffic- and energy-aware routing (TEAR) scheme to optimize the stability period in wireless sensor networks was explored. The proposed scheme exploits random initial energy and random disparity (multi-level traffic heterogeneity) of the sensor nodes to model a realistic clustering mechanism suitable for heterogeneous wireless networks. The TEAR scheme enhances the lifetime and stability of networks in a multi-heterogeneous scenario. Meanwhile, a novel relay-based multi-hop routing to improve the energy efficacy of D2D communication networks is introduced in [29]. The proposed routing approach improves the energy efficacy of D2D communication networks with a combinatorial optimization problem to attain a plausible solution. The result demonstrates that the proposed heuristic routing improves energy efficiency and network throughput and mitigates the computational cost more than other existing techniques. Next, ref. [30] explored an energy-conscious, dual-path geographic routing (EDGR) approach to provide efficient route recovery from the routing holes. The proposed protocol exploits the nodes' geographical location, remaining energy, and energy-consumption features in terms of route selection. It also dynamically utilizes two node-disjoint anchor lists, which are passing through the two sides of the routing holes to shorten the routing path and load balancing in the network.