## 7 Module III: Temporal Privacy
### Energy Controlled Anti Temporal Scheme (ECAT)
#### 7.2.4 Handling Rate Attack  
One issue that WSN with one sink could suffer from is having higher transmission rate next to the BS where messages ultimately need to reach out to the BS as the final destination. In contrast, periphery sensors far from the BS could have light transmission rates. Figure 17 illustrates the issue. This could jeopardize the location privacy of the BS. One solution is to have multiple sinks distributed in the network. This contradicts with the pre assumptions we set for our framework so we will not address this solution in this work. The framework needs to maintain similar average rate among all the sensors. This  
Figure 17: Higher transmission rate next to the BS. The figure exhibits about 20 transmissions near by the BS while one other area has 9 transmissions for the same period. This could be a bed for rate attack where the ADV can locate the BS [42].  
Figure 18: The area coverage of a central sink is higher than a peripherally sink. To balance the higher data rate nearby the sink, we acquire a higher density sensor distribution.  
could be achieved by increasing the number of fake messages transmitted by less busy nodes, which means increasing the bandwidth usage and the power consumption. We need also to reduce the fake messages sent by busy nodes or delay the real messages to maintain similar rates. The latter is achieved automatically since the sensors do not send fake messages when they have real messages. However, this could be better tuned for average busy nodes as well. Having balanced rate in the WSN could help to maintain balanced average lifetime for the nodes in the network. Presuming that all the nodes are heterogeneous in terms of energy would mean that busy nodes would be depleted sooner that could create an empty coverage area or a buffer zone between the sink and the peripheral SNs. This makes it a double fold problem. The first approach is to select a suitable location for the BS in the network map. Most of the literature shows a side location for the BS. It is maybe because it is more suitable for the applications in hand where the BS is connected to the backbone network in a reachable area and sensors are unattended in out of reach areas. Figure 18 exhibits that the coverage area of a central BS is much better than a side BS. The density of nodes closer to the BS should be higher. The range of transmission for sensors in higher density areas may need adjustment to control energy dissipation. We could have multiple density areas around the BS where the density is reduced, as it gets distant from the BS. Figure 18 exhibits only two density areas for simplicity. If the storage of the sensor is not big enough, which is unrealistic case with increasing storage technology in the sensors, then the sensor does not need to include all the neighbors in the tables. The network will be divided into two areas, near (A\({}_{\text{n}}\)) and far (A\({}_{\text{f}}\)). The framework will set average transmission rate (ATR) thresholds, R\({}_{\text{max}}\) and R\({}_{\text{min}}\). Sensors in A\({}_{\text{n}}\) will be loaded with R\({}_{\text{max}}\) where the sensors need to queue messages to maintain the threshold. In reverse, sensors in A\({}_{\text{f}}\) will be loaded with R\({}_{\text{min}}\) to maintain the lower threshold by sending more fake messages as needed. The sensor will calculate its average transmission rate over a period of time T\({}_{\text{arr}}\), which is preset by the framework.