"Submitted to: Submitted by:Under Supervision of:INDEX? Introduction…………………………………………….1? Definition………………………………………………3? Architecture of wsn…………………………………….5? Challenges and requirements of mac for wsn.………....8? Why mac for wsn……………………….…………… 10? Pairwise…………………………………..…………...11? Types of mac………………………….………………14? Mac protocols for wsn………..……………………….16? Conclusion…………………………………………….18? References……………………………………………..19 1 INTRODUCTIONWireless sensor networks are appealing to researchers due to their wide range of applicationpotential in areas such as target detection and tracking, environmental monitoring, industrialprocess monitoring, and tactical systems. However, low sensing ranges result in dense networksand thus it becomes necessary to achieve an efficient medium-access protocol subject to powerconstraints. Various medium-access control (MAC) protocols with different objectives have beenproposed for wireless sensor networks. In this article, we first outline the sensor networkproperties that are crucial for the design of MAC layer protocols. Then, we describe severalMAC protocols proposed for sensor networks, emphasizing their strengths and weaknesses.Finally, we point out open research issues with regard to MAC layer design.Improvements in hardware technology have resulted in low-cost sensor nodes, which arecomposed of a single chip embedded with memory, a processor, and a transceiver. Low-powercapacities lead to limited coverage and communication range for sensor nodes compared to othermobile devices. Hence, for example, in target tracking and border surveillance applications,sensor networks must include a large number of nodes in order to cover the target areasuccessfully.Unlike other wireless networks, it is generally difficult or impractical to charge/replaceexhausted batteries. That is why the primary objective in wireless sensor networks design ismaximizing node/network lifetime, leaving the other performance metrics as secondaryobjectives. Since the communication of sensor nodes will be more energy consuming than theircomputation, it is a primary concern to minimize communication while achieving the desirednetwork operation.However, the medium-access decision within a dense network composed of nodes with lowduty-cycles is a challenging problem that must be solved in an energy-efficient manner. Keepingthis in mind, we first emphasize the peculiar features of sensor networks, including reasons forpotential energy waste at medium-access communication. 2 "