## 2 Literature Review
The packets are then transferred via shortest path routing from the source node to the phantom nodes. From there, they are sent in either a clockwise or counterclockwise direction to reach the ring nodes and finally to the BS. In contrast to existing methods, this approach attains the highest degree of anonymity. Nonetheless, it is worth noting that the utilization of the same set of intermediate nodes for packet transmission may have implications for the network lifetime (NLT). In [34], two solutions with the names PRBRW and PRLPRW were put forth. In PRBRW, packets are sent oppositely initially, and then the greedy technique is used to get to the BS. The limitation of this approach is that there is no improvement in network lifespan. To deal with this limitation, a second strategy, namely, PRLPRW, was suggested. In this technique, the packets are relayed randomly initially and then sent to the BS using min-hop routing. The random walk consists of a vertically up-or-down walk followed by a horizontally left-or-right walk. These two phases sought to increase traffic uncertainty and diversify routing paths. However, the equilibrium between privacy, i.e., the safety period, and the network lifetime problem was not solved using these techniques. [PERSON] et al. proposed a new SLP scheme in [30] to enhance the privacy level of the source of information. In their scheme, the source node sets two candidate domains, and the proxy node that will serve as the source node is chosen from one of the candidate domains. Then, min-hop routing is used by the proxy node to forward the packets to the base station. Considering that the proxy node must be located within one of the candidate domains, all of which are established in close proximity to the source node in the same general direction, there is a potential vulnerability for the attack to discern the source node's location. This vulnerability arises from the lack of diversity in the routing path. Notably, there was no effort to enhance the network lifetime (NLT), despite the fact that the next hop for packet relay was chosen based on the remaining residual energy. The authors of [21] proposed an SLP scheme with the aim of protecting path location privacy and congestion avoidance by employing a jellyfish structure. Also, a network is divided into various subdivisions, and sensor nodes placed in these subdivisions select the target area by computing the transmission distance. A virtual ring and radial line are used to protect the routing path from a particular node to the sink, and congestion is prevented by the proposed alternate path routing. To streamline the communication channel between nodes and the sink, the network's configuration involves the simultaneous selection of the number of radial lines and the virtual ring radius. In this arrangement, bell nodes within the virtual ring are routed probabilistically with varying angular orientations, whereas radial line pathways maintain a fixed routing direction. While this setup appears to offer a notable level of privacy, the recurrent use of the same radial line pathways for packet transmission to the sink raises concerns about potential implications for the network lifetime (NLT). A bidirectional location-based SLP scheme was proposed in [20] by [PERSON] et al. for protecting both sink and source node. The scheme's objectives include improving source and sink node privacy and balancing the quality of end-to-end communication. However, the network lifetime was not taken into account by the authors. An enhanced solution, namely, PSSLP, was proposed in [16]. The PSSLP technique aims to achieve uniform privacy. The notion of dividing a network into different sections was adopted so that the packets, based on distinct phases, are transmitted to the base station. This protocol excels at elevating the privacy of the source node when compared to existing ones.