## 7 Protocol Comparisons
### Architecture Comparison
The system uses the geographical location information of mobile nodes, provided by global positioning systems (GPS), to confine the route searching space, for the specified destination node. WCA (A Weighted Clustering Algorithm for Mobile _Ad Hoc_ Networks) was presented in [41]. They proposed an on-demand, weight-based distributed clustering algorithm that takes into consideration the ideal degree, transmission power, mobility, and battery power of mobile nodes. The clustering algorithm tries to distribute the load as much as possible aimed to reduce the computation and communication costs. The algorithm is executed only when there is a demand, _i.e._, when a node is no longer able to attach itself to any of the existing cluster-heads. In [42] CLTC was presented, a Cluster-Based Topology Control Framework for _Ad Hoc_ Networks. CLTC uses a centralized algorithm within a cluster and between adjacent clusters to achieve strong connectivity. It utilizes a hybrid approach to control the topology using transmission power adjustment and yet achieves the scalability and adaptability of a distributed approach with localized information exchange between adjacent clusters. CLTC framework guarantees global k-connectivity as long as the original topology is k-connected. Table 3 compares the described protocols. The number of messages of some protocols is provided by the explanations of their authors in the referenced paper. Some of them do not take into account messages such as the new nodes messages or messages to provide fault tolerance, or are based on other algorithms not described in the paper (although in some cases we have found these and taken them into account). Many other proposals have been found in the literature, but they have not been included  
because of the lack of sufficient information in the original publication to fill in the rows of Table 3, or because the authors just described the algorithm, not the protocol, or because they are slight extensions of the proposals shown in the Table. Several features in our proposal may be highlighted. First, it is the only one that is able to use several routing protocols in the same network, and it does not depend on a specific routing protocol so it could be adapted to the environment issues. It does not have too many messages compared with the other ones (despite the simplicity of the CBRP, some procedures are not explained and it does not provide fault tolerance). Second, it is the only one where a new node selects the cluster not only by the proximity or radio signal strength but also takes into account the available capacity of the neighbors (which depends on the available energy). Third, it is the only one that has been proposed to create parallel networks. Our proposal has been designed to provide fault tolerance and our design is described in detail giving all the messages needed to run properly. There are several differences in the metric used to elect the Cluster Head. Some of them use the lowest _NodeID_ or their position, while others use just a random system. Others are not explained or propose a weak system. Between the most complex metrics, we distinguish CBLARHM that uses a node-weight heuristic parameter, based on the ideal number of nodes in a cluster, the battery power, the average link stability and the average dependency probability, to elect the head cluster node, but this is very impractical because it is difficult to determine the value of some of these parameters.