## 2 Categorization and Classification of Quality of Service Routing Protocols
### Deterministic Routing Protons (Soft Real Time)  
GRAdient Broadcast (GRAB) is specifically designed for robust data delivery in order to control unreliable nodes and imperfect wireless links [45]. GRAB constructs and maintains the cost field by broadcasting advertisement (ADV) packets. When a node gets an ADV packet comprising the cost of a sender, it computes its cost by accumulating the link cost between sender to sender cost advertisements. The node compares this cost with the previously verified one then sets a new cost. When the node gets a smaller cost than the older one, it transmits an ADV packet containing the new cost. GRAB handles bandwidth by using an amount of credit taken in each data packet, that lets the sender regulate the strength of data delivery. The benefit of GRAB is to reply upon the communal efforts of the multiple nodes in order to distribute data without any data dependency on any individual node. However, it increases overhead by using redundant data. The Directional Geographical Routing (DGR) Multipath routing protocol was introduced in [46]. DGR is suitable for real time video streaming over energy constrained nodes and bandwidth from a small number of detached video sensor nodes (VNs) to a sink by merging a forward error correction (FEC) coding technique. In DGR an active node VN broadcasts the packets to its direct neighbors while concatenating FEC packets of a video frame and all the data. When nodes get concatenated  
Figure 5: Queuing theory for proposed algorithm [44]. packets broadcast by the VN, they choose their own payload on the basis of the sequence numbers and identify the corresponding packets of nodes. Subsequently, nodes unicast the allotted packets to the sink through corresponding individual paths. In DGR, multipath routers set three paths between the source and the sink. Furthermore, each path uses a different first direct neighbor. This architecture can be efficient to route the video traffic of the network. The simulation results prove that DGR achieves a low latency equal to 0.05 ms. It also increases network lifetime and provides a better received video quality. The video peak signal to noise ratio could be improved up to 3 dB. Energy efficient and QoS aware routing (EEQR) is a deterministic real-soft routing protocol introduced in [47]. Guaranteeing the QoS, the data prioritization is performed based on the message type. Two types of sink nodes were used: static and mobile. The static sink nodes handle the delay-sensitive messages, while mobile sinks handle the delay tolerant messages. The objective of EEQR is to improve network lifetime and coverage efficiency. In addition, it focused on the QoS parameters such as end-to-end delay, packet loss ratio, and throughput. EEQR is based on the multi-hop communication which reduces the end-to-end delay and bandwidth consumption. The packet prioritization mechanism handles the data gathering issue. Incoming traffic of the network is ranked according to the packet content significance. The proposed EEQR is divided into phases and sub-phases. The primary phases includes: setup and steady. The sub-phases comprise eight sub-phases. The setup phase involves the initialization, route update, and clustering three sub-phases. The Steady Phase consists of six sub-phases: data prioritization, data forwarding to cluster head or super node, data forwarding to static sink, mobile sink movement decision, forwarding queue weight to mobile sink, and mobile sink data gathering. The QoS based and Energy aware Multi-path Hierarchical Routing (QEMH) protocol is introduced in [48] to fulfill the QoS requirements and energy consumption needs. QEMH is designed based on a hierarchical mechanism for consuming the minimum energy. The protocol consists of two phases. In the first phase, the QEMH selects the cluster head node based on two metrics: node distance from the sink station and residual energy of the node.