Throughput and Age of Information in a Cellular-based IoT Network

Abstract : This paper studies the interplay between device-to-device (D2D) communications and real-time monitoring systems in a cellular-based Internet of Things (IoT) network. In particular, besides the possibility that the IoT devices communicate directly with each other in a D2D fashion, we consider that they frequently send time-sensitive information/status updates (about some underlying physical processes observed by them) to their nearest cellular base stations (BSs). Specifically, we model the locations of the IoT devices as a bipolar Poisson Point Process (PPP) and that of the BSs as another independent PPP. For this setup, we characterize the performance of D2D communications using the average network throughput metric whereas the performance of the real-time applications is quantified by the Age of Information (AoI) metric. The IoT devices are considered to employ a distance-proportional fractional power control scheme while sending status updates to their serving BSs. Hence, depending upon the maximum transmission power available, the IoT devices located within a certain distance from the BSs can only send status updates. This association strategy, in turn, forms the Johnson-Mehl (JM) tessellation, such that the IoT devices located in the JM cells are allowed to send status updates. The average network throughput is obtained by deriving the mean success probability for the D2D links. On the other hand, the temporal mean AoI of a given status update link can be treated as a random variable over space since its success delivery rate is a function of the interference field seen from its receiver. Thus, in order to capture the spatial disparity in the AoI performance, we characterize the spatial moments of the temporal mean AoI. In particular, we obtain these spatial moments by deriving the moments of both the conditional success probability and the conditional scheduling probability for status update links. Our results provide useful design guidelines on the efficient deployment of future massive IoT networks that will jointly support D2D communications and several cellular networkenabled real-time applications.

 EXISTING SYSTEM :

 ? Real-time status updates are indispensable for many key applications, such as predicting and controlling forest fires, safety of an intelligent transportation system, and efficient energy consumption in future smart homes. ? A common setup for status update systems is the existence of a source node that generates update packets, and then transmits them through a communication system to a destination node. ? The CoUD can take any form of a payment function, which is non-negative and monotonically increasing, to quantify the cost of information absence at the monitor. ? The type of cost function needs to be properly chosen based on the statistics of the observed stochastic process at the source.

 DISADVANTAGE :

 ? They derived bounds on the spatiotemporal mean AoI, the spatio-temporal mean peak AoI, and the spatial distribution of the temporal mean peak AoI, by incorporating system modifications to deal with the issue of correlated queues. ? It is important to accurately model the spatial distribution of wireless devices to analyze the impact of spatial variations on the achievable QoS. ? We highlight the impact of the power control on the achievable D2D network throughput and the spatio-temporal mean AoI for different system design parameters. ? The impact of SIR thresholds on the spatio-temporal mean AoI of status update transmissions and the throughput of D2D network.

 PROPOSED SYSTEM :

 • An analytical model was proposed in order to evaluate the Age of Information of a VANET. • Quality scores are useful to simplify the complexity and diversity of applications QoSs, such as the scoring system proposed in along with a mapping mechanism for multiple QoS attributes in order to find the optimal deployment decision with the highest overall application level quality score. • An access WSN gateway was proposed in to provide end-to-end (E2E) connectivity for Machine Type Communication (MTC) traffic flow within the license spectrum of LTE-APro media. • The evolution of the request rate was analysed in two versions of the proposed model, providing sufficient conditions for the settling time of request rate.

 ADVANTAGE :

 ? It is worth noting that the prime focus of the works in was on performing the spatiotemporal analysis of conventional performance metrics such as transmission rate and delay. ? However, in status updating systems, information freshness is more important than the commonly used performance indicators, such as data rate or delay. ? While this spatio-temporally averaged coverage probability provides useful insight into the network design, it is not sufficient to study the spatial disparity in the link-level performance of the network as discussed above. ? We captured the spatial disparity in the AoI performance by characterizing spatial moments of the temporal mean AoI.