## 4 Self-Selective Routing (SSR)
### Route Repair in Self-Healing Routing (SHR)  
Another fundamental addition to SHR [24,53] is the inclusion of a route repair mechanism for propagating packets across faulty routes. According to SHR, a faulty route is that where a source node is the one with the minimum distance to the destination compared with its neighbors. In this situation, based on the topology condition, a suitable method needs to be considered to re-route the packets across the shortest route. In SHR, this is achieved by simply adjusting the hop counts of the sending node. Below are the steps for implementing route repair in SHR using the DATA and HELLO packets. For sending packets:From the beginning, before transmitting an unseen packet, a resend bit is set in the packet header to zero, and then the timer timeout is set; subsequently, the packet is transmitted to the destination. 2. In case there is no response apart from the previous sender acknowledgement (ACK) before the timer expires, the packet is resent by setting the reset bit to one. 3. Else, if a response is received, an explicit ACK packet is sent. However, if the expected hop distance of the respondent is not one less than the hop count, the hop counts that correspond to the packet destination are substituted with one greater than the expected distance. 4. If there is no response to a retransmitted packet, a higher protocol layer is signaled to take the next action. In this case, the source or sender now becomes isolated, and there is no need for transmission. 5. After receiving ACK for a retransmitted packet, the hop count of the packet destination is increased by two, and the maximum of the current and expected hop count from the response packet. Next, an explicit ACK is sent [24, 53]. For packet receivers:  
1. For a given network packet with a resend bit initially set to zero, if the packet destined for a particular destination has already been received, do nothing. 2. Otherwise, continue as normal and compute the transmission back-off delay using Equations (2) and (3). In our approach, we address the limitations of the SHR and SSR routing protocols by using combined continuous and slotted prioritized transmission back-off delay to obtain local and global network state information and multiple randomize function for faster routing convergence and efficient and reliable route repair technique in the presence of transient and permanent node failure rates. Proposed Approach to Autonomous Self-awareness and Adaptive Fault Tolerant Routing Technique (ASAART)  
In order to demonstrate our approach using autonomous self-awareness and adaptive routing techniques, namely ASAART, we consider low duty-cycle wireless sensor networks [14, 15, 16, 17, 18, 19, 33]. In this type of network, the sensor nodes remain sleeping most of the time and wake up asynchronously in the case of event transmission. Therefore, the concept of probabilities that forwards a decision based on the delay distribution of the destination nodes can be employed [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57]. In doing so, only packets are transmitted in order to achieve shorter delays and reduce packet redundancy. The probabilistic approach signifies that when a sensor node receives a network packet, the packet is forwarded with given probability \(\delta\). Such probability \(\delta\) is computed by the network state information obtained from individual neighboring nodes. The routing decision is computed using the improved formula given in Equations (4)-(10). The SHR [24, 53] and SSR [40, 41, 51, 52] algorithms use more redundant transmission and retransmission of packets. Our approach attempts to reduce such redundant packets. SHR and SSR make use of prioritized back-off delay for forwarding packets, and only the receivers of the forwarding packet reach the destination.