# Sensing and Device Neighborhood-Based Slot Assignment Approach for the Internet of Things
## 4 Proposed Neighborhood-Enabled TDMA Approach
### TDMA-Enabled Communication Strategy
Therefore, a device \(C_{i}\), preferably a member, is required to deliver an updated version of the received message \"MSG-Q\" with a value of S or M if it wishes to interact during the next session. If and only if the relevant server module does not get any message in response to its inquiry message, it is presumed by default that the device is not interested in communication in the next session. It should be noted that the shift probability distribution \(P_{shift}\), as indicated in the equation, is used to assign the extra free slots (6). \[p_{shift}(C_{i})=\frac{(1-\gamma)\gamma^{k}}{(1-\gamma^{k})}\cdot\gamma^{s} \tag{6}\]  
In this equation, variable s has values ranging from \(1\ldots k\), where \(k\) depicts the available free slots number. It is interesting to note that the effective utilization of these slots is one of the main motivations behind this scheme. Additionally, in this scheme, the server module needs to ensure a minimum possible empty slot ratio, preferably zero, in every cycle or frame. Values range as \(0<\gamma<1\) and \(\gamma=C_{1,2,3,4\ldots n}\frac{1}{K-1}\) such that \(C_{1,2,3,4\ldots n}\) is used to describe a complete set of devices \(C_{i}\), especially contestants or participants. The strategy adopted for the proper management and allocation of the multiple available slots is depicted in Equation (6). It is important to note that a device allocates multiple slots **iff**, and multiple contestant devices \(C_{i}\) are eager to allocate more slots for communication. Additionally, the process should follow either a sequential order or a prioritized fashion to handle such types of scenarios. However, this strategy is not applicable in situations where every device \(C_{i}\) has data to transmit, and, thus, free slot availability is negligible. Additionally, the respective server \(S_{j}\) will ignore such requests if free slots are not available. In addition to this methodology, a server \(S_{j}\) may be assigned additional responsibilities, i.e., it will forward the data values of those servers \(S_{j+1}\) where it is not feasible for them to transmit packets directly. Therefore, these servers communicate with the nearest server through the dedicated slot that is reserved for this purpose. To implement this, a few slots, i.e., in every server \(S_{j}\), are kept and allocated from **iff** to another server \(S_{j+1}\) to make a request. Servers \(S_{j}\), which do not have the capability to transmit directly, must follow the methodology presented by the following Equation (7), i.e., \(\forall_{j=0...m}\;S_{j}\in\sigma(S_{j+1})\) for **iff**. \[\frac{\sqrt{(S_{x_{i}}-BS_{x_{j}})^{2}+(S_{y_{i}}-BS_{y_{j}})^{2}}}{(x_{i}\;+\; y_{j})}\;<\;\delta \tag{7}\]  
Additionally, time slots need to be kept for servers \(S_{j}\), which are either placed on edges or far away from the respective sink module in an IoT network. These devices are deployed at a distance, i.e., far beyond the range of the communication module. Slots are reserved according to Equation (8), that is, \(\exists_{j=0...m}S_{j}\in\sigma(S_{j+1})\) for **iff**. \[\frac{\sqrt{(S_{x_{i}}-BS_{x_{j}})^{2}+(S_{y_{i}}-BS_{y_{j}})^{2}}}{(x_{i}\;+\; y_{j})}\;==\;\delta \tag{8}\]  
In this equation, the variable \(\delta\) is utilized to present the capability of the respective Xbee or radio module, which is preferably wireless, of the \(S_{j}\). However, as opposed to the mechanism adopted for the allocation of temporary time slots to the respective devices \(C_{i}\), slots reserved for other server modules are dedicated and are not assigned to another server \(S_{j}\). Let us consider a scenario that is depicted in Figure 1, where Server-1 \(S_{j}\) has six member or neighboring devices \(C_{i}\). Initially, Server-1 initiates the process by broadcasting a control message \"\(MSG_{b}\)\" to identify potential neighboring devices \(C_{i}\). It is quite possible that those devices installed in close proximity or vicinity to the respective server \(S_{j}\) will receive this message, i.e., \(C_{1,2,3...6}\).