دانلود رایگان مقاله انگلیسی رزرو طرح کنترل دسترسی متوسط برای شبکه های بی سیم تک هاپ - نشریه الزویر

abstract

The major challenge pertaining to single-hop wireless networks is to design a medium access control (MAC) scheme to efficiently utilize the scarce wireless bandwidth; whereas the most popular solution, IEEE 802.11 distributed coordination function, achieves only limited performance because of the considerable idle time and the high rate of transmission collisions caused by the backoff procedure at high loads. In this paper, we propose a novel contention/reservation MAC scheme, which aims at ensuring low control overheads and collision-free data transmission to maximize system performance. Our scheme provides an efficient control contention resolution algorithm which resolve one or at least one successful reservation in a time frame, thus only a few numbers of control minislots are necessary for a number of active mobile stations contending for reservations. Moreover, with the help of the broadcast messages from the Access Point, all mobile stations determine a nearly-round-robin and collision-free data transmission schedule in a distributed manner, and also implicitly resolves the well-known hidden terminal problem. Extensive simulation results demonstrate that the proposed MAC scheme achieves exceptional system performance under a wide range of traffic loads and various system parameters, and also shown to be robust even when under attack by malicious mobile stations

6. Conclusions

We have proposed a novel contention/reservation MAC scheme for single-hop wireless networks. The scheme demonstrates two prominent features. First, it provides an efficient controlcontention-resolution mechanism that resolves one (or at least one) successful reservation, resulting in only few numbers of control minislots are needed for a number of active mobile stations contending for reservations. As revealed in the simulation results, under the system parameter (C = 2), the network system averagely requires less than five number of control minislots for a small group of MSs (e.g., N = 10). Second, collision-free data transmission is ensured. Once an MS reserves successfully on any control minislot, the MS is allowed to transmit several data packets in a roundrobin order among the other successfully reserved MSs. With the help of the broadcast messages from the AP, all mobile stations determine a collision-free data transmission schedule in a distributed manner and also implicitly resolve the well-known hidden terminal problem. To conclude, by reducing the control overheads and fully eliminating the data collisions, the scheme exhibits exceptionally high system performance compared with the conventional IEEE 802.11 DCF and PCF protocols.