tailieunhanh - Petri nets applications Part 6

Tham khảo tài liệu 'petri nets applications part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CL-MAC Cross-layer MAC Protocol for Delay Sensitive Wireless Sensor Network Applications 191 CL-MAC exploits the routing information through a cross-layer design approach based on interaction strategy. In this strategy CL-MAC interacts with the adjacent routing layer by using a simple Get Store mechanism on a common memory storage dedicated to store the Delay sensitive local traffic Fig. 9. CL-MAC interaction between MAC and network layers current routing information see Fig. 9 . This mechanism allows the routing agent to write in common memory information about the next hop forwarding node to which the current sender must forward a packet. This routing information can be obtained and exploited thereafter by CL-MAC to carefully perform a cross layering MAC operation. By knowing the next hop each time it advances in the routing path CL-MAC can reserve a shared wireless medium during a time involved in each data communication. In Fig. 9 we have proposed the IEEE IEEE 2003 standard at the physical layer which is dedicated at the origin for Low Rate-WPAN networks but it is also very adapted for the WSN because it is designed for low-data-rate low-power-consumption and low-cost applications. New Data structure for RTS and CTS Before describing further details about CL-MAC operations one should be aware that weak modifications are made in RTS and CTS message structures without violating the IEEE standard. The modified message structures of RTS and CTS illustrated by Fig. 10- a and b are proposed. The newly added field in RTS is the Next_Node_Adress obtained by the sender s routing agent and designates the address of the next node in the routing path to which packets must be transmitted. The new fields of CTS are Next_Node_Adress and Sender_Adress . The Next_Node_Adress field has the same significance than Next_Node_Adress of an RTS packet but it is obtained by the routing agent of the receiver of the CTS packet. By specifying its address in a .