# Multipath Routing in Wireless Body Area Sensor Network for Healthcare Monitoring
## 3 Proposed Methodology  
### Design of Region-Based Energy Efficient Multipath Routing Algorithm  
Figure 1 presents the design artifacts of the region-based energy-efficient multipath routing approach (REMR) that provides low-energy, trustable, and efficient routing in WBAN for healthcare monitoring. In REMR, the WBASN nodes are divided into clusters and preferably multiple nodes are selected as CRs in each cluster which helps in routing packets through various clusters by the selection of a path with the least energy requirement. Algorithm 1 shows how the clusters are formed based on energy level and least distance from BS. Nodes D and E are the candidate gateway for cluster A, while the I and J nodes represent cluster B. If F needs to send data to the base station, it has an alternate path using J, E, and I nodes. The source node F has paths from its region, while it has another alternative of sending data using cluster A's candidate node E.  
REMR works in three phases: route discovery, route maintenance, and data transmission. Initially, when node F needs to transmit data to BS, it finds no direct path. It floods route requests to its neighbors J and I, and obtains responses, being the candidates. While node E via A also offers its service from the other region. F preferably selects J and I nodes and uses both paths to send data. A packet-wise approach is used in scheduling for transmitting data to the base station. The CRs are selected by the base station (BS) based on their distance from the BS. The BS also selects multiple nodes to serve as intermediate clusters with no direct access to BS. Clusters near BS will route traffic using multiple paths and multiple CRs, resulting in decreased energy consumption for network propagation, route discovery, and control messages. We assume that the BS does not have any buffer constraints. For packet routing, the selection of a cluster candidate (CC), from the available CRs, is made based on its energy level (battery backup measured in joules) and its distance to the next hop. The selection  
Figure 1: System architecture for region-based energy-efficient multipath routing. criteria of CC are given in Equation (1), where \(E_{i}\) is the energy level of node \(i\) and \(T^{{}^{\prime}}\) is the threshold value. \[ \begin{cases}E_{i}>T^{{}^{\prime}}\\ \Delta d=MIN(\Delta x,\Delta y,\Delta z,...,\Delta n)\end{cases}  \tag{1}\]  
```
0: Set of WBASN nodes with their energy levels and coordinates
0: Set of clusters of WBASN nodes (S)
1: Begin:
2: Let Routing Table (RT) of WBASN node be \(\phi\)
3: Let R' be the range of BS
4:for each cluster \(C_{i}\)do
5:for each WBASN node \(S_{i}\)do
6: hopCount = closest neighbor hop
7: minDist = strongest wireless range
8:for each WBASN node \(S_{j}\) in cluster \(C_{i}\) where \(i\
eq j\)do
9: Get total resource value \(r_{i}\)
10: // Calculate 1-hop neighbors based on Range R'
11:if\(S_{j}\) in Range of BS and hopCount = 1 and minDist = TRUE then
12: // if \(S_{i}\) is neighbor node or at 1-hop count
13: Assign \(S_{j}\) as \(C_{i}\)
14:endif
15:endfor
16: Update RT
17:endfor
18:endforreturnS end:
```  
**Algorithm 1** Cluster formation based on energy level and shortest distance  
A CR cannot be a CC if its energy level is less than the defined threshold value. This is to ensure that the node has the required energy to stay alive and transmit data. A CC must lay in the shortest path from the source node to the destination, while it should also be the node nearest to the source node. The selection of such a candidate will ultimately require less emitting power to generate signals, and hence, improved energy utilization will be achieved. Additionally, for a CR to be selected as CC, it must be the nearest node to the next hop having a distance \(\Delta d\) to the source. Using multiple CRs serves as a cluster to become connected with BS with alternative paths available. Such candidates can help reduce the required transmission power due to the least transmission power requirements.