## 4 Classification of Routing-Related Surveys
### Least Focused Areas
#### 4.3.2 Geographic Based Routing Surveys  
These surveys consider such routing protocols where sensor nodes have either Global Positioning System (GPS) or some location-aware system that may help to provide awareness about their position. On the basis reviewed literature, these protocols may be classified into three categories as discussed below:  
\begin{table}
\begin{tabular}{c l c} \hline \hline \multicolumn{1}{c}{**Survey Type**} & \multicolumn{2}{c}{**Categorization and Design Requirements Based Analysis of QoS-based Routing Surveys**} \\ \hline \multirow{2}{*}{**Typical based**} & _Md_ & [77; 106; 113] \\ \cline{2-3}  & _Lw_ & [50] \\ \hline \multirow{2}{*}{**Multipath based**} & _Hg_ & [111] \\ \cline{2-3}  & _Md_ & [58] \\ \hline \multirow{2}{*}{**Config-Handling based**} & _Hg_ & [81] \\ \cline{2-3}  & _Hg_ & [141] \\ \cline{2-3}  & _Md_ & [117; 123; 125; 140] \\ \hline \hline \end{tabular}
\begin{tabular}{l l c} \hline \hline \multicolumn{1}{c}{Hg* = High Count, Md* = Medium Count and Lw* = Low Count. Note: Various categories of count correspond to Count Number Index (CNI) in Tables 2 and 3.} \\ \hline \hline \end{tabular}
\end{table}
Table 10: Design analysis of QoS-based routing surveys in WSNs.  
In mobile based categorization, such surveys are discussed which consider mobility as main focus and categorize routing protocols on the basis of network structure (such as grid-based, cluster-based, tree-based, zone-based), state of information (such as proactive-based, reactive-based, hybrid-based), energy-efficiency (such as power control and saving, load-distribution-based), mobility (sink-only, node-only, hybrid) and biologically inspired routing.
* In location-based categorization, the classification metric may be flooding-based, curve-based, grid-based, geography-based and trajectory-based while mobility is not generally focused.
* The partial geographical categorization includes those surveys which consider some aspects/protocols of geographic routing in WSNs.  
In case of the surveys with complete emphasis on routing such as [43; 44; 94; 109], the routing protocols are categorized by employing mobility based classification. The protocols in [43; 44] consider only mobile sink based routing protocols whereas [94; 109] considers mobility in general. The authors in [55] have mainly classified routing protocols using location-based categorization while [91] delineates brief discussion regarding location-based routing protocols in WSNs. In [109], the authors have discussed and compared the characteristics of various mobility-oriented hierarchical routing protocols. Highlighting the applications of discussed protocols is helpful in protocol development in the corresponding fields in future. In [43; 91], the authors have discussed challenges of location-based and mobility based routing respectively. The authors in [94] have discussed general issues of mobility in WSNs. Future research challenges are delineated in [43; 44; 55; 94; 109]. Moreover, it is apparent from Table 11 that this stratification contains 3 high count, 2 medium count and 1 low count surveys.  
The surveys having partial emphasis on routing include [137; 142]. In [137; 142], the authors have discussed routing protocols under restricted geographical categorization. The authors in [142] have described some micro-mobility oriented routing protocols which may or may not consider triangular routing in their operations. The authors in [137] have discussed general issues of mobility in WSNs while [142] outlines design issues and challenges of mobility management in 6 LoWPAN based WSNs. Future research challenges are delineated in [137; 142].