You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: A Survey on Energy Efficiency and Cluster Handling in Real Time Wireless Sensor Networks 
Chapter Title:  V. 
1. Abstract of Cited Paper (BIB001):  In wireless sensor networks (WSNs), hierarchical clustering approach gives an efficient solution to achieve the goal of maximizing the network lifetime by minimizing energy utilization. In this paper, we introduce a cluster head (CH) selection process and cluster formation algorithm by re-selection of CHs called Improved Energy Efficient Hybrid Clustering Scheme (IEEHCS). In the proposed scheme, energy efficient CHs are selected by a centralized algorithm based on remaining energy, node density and minimum separation distance to reduce the control message overheads. The key idea is that the CH role is repeated with the same settings or shifted to a eligible member nodes instead of re-clustering the whole network at every round. In this way, IEEHCS reduces the frequency of updating CHs, avoids unnecessary re-clustering in every round and saves significant amount of node energy. Simulation results demonstrate that IEEHCS effectively reduces the energy consumption and prolongs the network lifetime for first node death upto 45.39% and 11.36% over LEACH-C and EEHCS, respectively, in certain network settings. 
2. Abstract of Cited Paper (BIB002):  The sensor nodes deployed in wireless sensor networks (WSNs) are strictly energy constrained. Thus energy conservation for maximizing lifetime of the network is central to the design of WSNs. In many applications, the nodes nearer to the sink are overburdened by means of huge traffic load as the data from the entire region are forwarded through them to reach to the sink. As a result, their energy is shaded rapidly and the network is partitioned. This is commonly known as hot spot problem. On the other hand the equal size clusters waste energy according to the network density. This problem is called equal size clustering problem. In this paper, we address both the hot spot and equal clustering problems and present unequal size clustering and routing algorithms by considering the energy efficiency of the WSN. The algorithms are tested with various scenarios of WSN. The experimental results show that the proposed algorithms perform better than the existing ones in terms of life time of the network, average energy consumption of a node and number of active sensor nodes.

Literature Review:
Reviews In HUCL, the network layers are divided into groups of different sizes. Available energy of nodes is the basis for choosing the cluster head, and were also chosen based on the number of neighbors to the sink. Once the group is formed, the same structure is maintained for a few rounds. Data with a data compression algorithm in a multi-hop network layer-based communication is sent through to the sink. In comparison with existing protocols, HUCL balances energy and its groups achieves a good distribution in the network, extend the lifetime of the network and avoid the energy hole problem. Ameer Ahmed Abbasi.et.al. [3] publishes a general classification of clustering schemes. Presenting different clustering algorithms for WSNs survey; Its objectives, features, complexity, etc. Also highlighted the convergence rate of such clustering, cluster stability, overlapping clusters, support for location awareness and node mobility as compared to algorithms based on metrics. Giuseppe Anastasi a .et.al.  author presents the energy consumption of the components of a typical sensor node, and discussed the main directions for energy conservation in WSNs. However, energy conservation schemes, which are discussed in the depths in a systematic and comprehensive classification. Special attention promising solutions such as energy-efficient data acquisition techniques that have not yet received widespread attention in the literature has been devoted to. Finally research directions for energy conservation in WSNs are concluded. Chengfa Li et.al.  proposes the energy-efficient unequal clustering (EEUC) mechanism for periodic data gathering in wireless sensor networks. The nodes split into groups of unequal size and the size of the group closer to the base station is smaller than those further away from the base station. Thus the nodes closer to the base station can preserve some energy for data forwarding in intercluster communication. Also an energy-aware multihop routing protocol for inter-cluster communication proposed. Simulation results show that uneven clustering mechanism well among all sensor nodes balances the energy consumption in the network also network lifetime achieves a clear improvement. Jun Luo Jean-Pierre Hubaux et.al. BIB001 shows that the base station should have mobility so that sensors close to it change over time as they have to relay data due to which their batteries runs out quickly. If the mobility and multi-hop routing dynamics both are taken into account by the base station then data collection protocols can be optimized. It is conclude that the best perimeter of the network mobility strategy are (it is assumed that the sensors are deployed within a circle) consists in the periphery. So in this case jointly consider mobility and routing algorithms, routing round and a better strategy uses a combination of routes and minor roads show. For each of the statements provided a detailed analytical model, and simulation results confirm this. In terms of the lifetime of the network 500% improvement is achieved. Dinu gopal et.al.  In this paper, a novel routing technology proposes routing schemes VGDRA and VCCSR for data collection. By using a hybrid scheme, it become possible to find a balance in energy consumption, average delay and lifetime. VGDRA reduce the cost of rebuilding of routes whereas VCCSR will reduce energy consumption and increase the lifetime of the network. Yan Gu et.al.  propose a multi layered clustering algorithm for network to balance the energy between clusterheads. After that performance of this approach is evaluated with simulation. The result shows that this algorithm is energy efficient and also increases network lifetime. Hairong Zhao et.al.  proposed a protocol for better establishment of Cluster and data transmission path. In the process of setting a cluster, a timer is introduced so that optimal sensor node should be elected as cluster head. During transmission of data, single-hop and multi-hop hybrid routing to communicate more effectively and evenly. An example simulation algorithm is provided to demonstrate the utility which greatly increase the network life and low energy consumption compared to LEACH algorithm. Debashis De et.al.  is changing the transmission ranges of nodes temporarily for that "bubbling mechanism" is proposed here, the concept of "cluster border" in which clusters at the border are having more number of active nodes than internal clusters. We also increase the efficiency of data collection by using dual sink i.e static sink and multiple mobile sinks. Approximately 10.62% of the energy of loaded cluster head is saved by using this mechanism. Rabia Noor Enam et.al.  In this paper, energy consumption has been calculated for the transmission of data from the sensor nodes to sink. It has been shown through extensive simulations that 20% of the total energy consumption of the network expires in the process of CH selection phase only. This energy consumption can be taken as an overhead power. An energy-efficient "round rotation" mechanism is proposed to overcome this overhead energy. By introducing RR technique with random CH selection phase, overhead energy of the network is reduced by 4% during data transmission. The result has been augmented by 20% of the network lifetime. Zohare. Arabi et.al.  An algorithm for Hybrid energy efficient routing is proposed that uses the two algorithms, i.e EF-Tree (earliest-first tree) and SID (source-Initiated Dissemination) to disseminate the data and a fuzzy method is employed for selecting cluster heads, and to switch between Sid and EF-tree. In this way, the whole network is grouped into cluster and fuzzy method is used to choose cluster head according to BIB002 In this paper, an energy-efficient hybrid clustering scheme (IEEHCS) is introduced which is a cluster formation algorithm and a selection process is also proposed here. In the proposed scheme, centralized algorithm is used for selection of energy efficient CHS which also depends upon remaining energy, node density and minimum separation distance between the nodes to reduce overheads. The main idea is that the CH role is repeated with the same settings again and again in each round and is shifted to an eligible member nodes instead of re-clustering of whole network. Thus, IEEHCS, reduces the frequency of updating the CHS in each round and avoids unnecessary re-clustering which saves a considerable amount of energy. Simulation results that IEEHCS effectively reduces energy consumption of energy and improves the lifetime of the network for the first node death by 45.39% and 11.36% compared to Leach-C and EEHCS respectively. Rajesh Purkait et.al. BIB003 this paper address problem of hot spot and equal clustering problems and by considering the energy efficiency of WSN routing algorithms and unequal size clustering is proposed here. These algorithms are tested with different scenarios. Result shows that the proposed algorithm is better in terms of a no. of active of nodes in network, average energy consumption and network lifetime.