Research On Simulation Of MAC CSMA/CA In Typical Short-Range Wireless Communication Networks

With the rapid development of wireless networks, especially wireless LAN has been ubiquitous in the world and the growing variety of electronic products, people needs for low power and low-cost short-range wireless personal area network development are also growing. Recently presented with the Interconnection-of-Things technology, wireless sensor network (WSN), make the rapid development contributed to booming of ZigBee network.This paper describes several short-range wireless communications technology, including 802.11 wireless access technology and 802.15 series of wireless access technology. They represent the wireless LAN and wireless personal area network typical standards.They were also the hot topic in the current academic research. As the IEEE802.15.4 application that is essentially similar to IEEF802.11 with CSMA/CA mode in communications, so the MAC layer's CSMA/CA mechanism is the focus of this article.This paper describes IEEE802.11DCF (CSMA/CA), proposes various typical improved Binary Exponential Back-off (BEB) algorithms, and gives more attention to the EBA (Early Backoff Announcement). Then introducing an improved idea of simplified reservation backoff algorithms which directly added a field with next-node's back-off time at the end of the data flame.This idea could reduce the trouble of distinguishing backoff time slot and sending slot in EBA.It could reduce the control overhead, directly reflect the nature of EBA algorithm idea.Based the basis of the future study with EBA algorithm in NS2.Then introduces the main features and structure of IEEE802.15.4 MAC layer. CSMA/CA algorithm in IEEE802.15.4 is also introduced too.Finally, the simulation module of Mac802.11 in NS2 was modified and extended to implement the simulation of reservation backoff algorithms by NS2. Simulation results indicate, compared with 802.11DCF, the reservation backoff algorithms also can enhance the performance of IEEE802.11 WLAN in throughput, delay and so on. BE, CW and beacons are different in CSMA/CA of IEEE802.15.4 MAC.By using NS2 to analyze the change of performance of the network with different values (just like throughput, delay and send rate) of these parameters.In the last, I made the appropriate adjustments in simulation.and compared with the reference of the simulation results obtained.