The Internet of Things describes the ever-growing network of internet-connected physical devices that uses an IP address for internet connection and communication with smart objects

The Internet of Things describes the ever-growing network of internet-connected physical devices that uses an IP address for internet connection and communication with smart objects. The base technology for IoT can be considered as wireless sensor networks (WSNs) in which smart sensors interconnected to sense and monitor various applications like smart home, health care, smart city, farming etc.5 IEEE 802.15.4 standard defines specifications of the PHY layer and MAC sub-layer in 6LoWPAN networks.6 Actually, many research papers are focused more to evaluate the performance of the 802.15.4 MAC protocol in terms of throughput and energy consumption.
In 7 consider exponentially distributed packet generation times, and do not assume simultaneous transmission attempts by all other sensor nodes after an inactive period. Under this situation, they do not find any MAC unreliability problem and reliability.
In 8, the authors developed the hybrid MAC protocol, for wireless sensor network to adapt to the level of contention. But, it behaves like TDMA under high contention and like CSMA under lower contention.
As in 9, they also propose some changes in MAC protocol to overcome congestions after an inactive period by introducing a random delay before the channel access. This issue can be solved with setting CSMA/CA parameters appropriately, without any modification to the standard MAC protocol.
In 10, the authors have evaluated the performance of slotted CSMA/CA using Markov chain model. These Markov chain model are interested in computing the throughput and delay .But, failed to address the impact of random backoff exponent and order of super frame.