Medium access control

Nominal transfer rates up to 11 (802.1 lb), 54 Mbps (802.11 a, g) and 600 Mbps (802.1 In) are specified. CSMA/CA is the medium access control. Wireless communications, wave propagation [2, 3] and practical implementations of WLANs [4] have been studied. Detailed information has been given about the... 

IEEE Standard 802.11b-1999, Part 11 Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications — Higher-speed Physical Layer Extension in the 2.4 GHz Band, 1999. 

Medium access control (MAC) for wireless ad hoc networks is currently a very active research topic. The characteristics of the network, the diverse physical-layer technologies available, and the range of services envisioned render a difficult task the design of an algorithm to disciphne the access to the shared medium that results efficient, fair, power consumption sensitive, and delay bound. A number of issues distinguish wireless MAC protocols from those used in wireline networks (Chandra, 2002), as quoted next. 

Chandra, A., Gummalla, V., Limb, J.O., Wireless Medium Access Control Protocols, IEEE Communications Surveys and Tutorials [online], vol. 3, no. 2, 2000, available at http //www.comsoc.org/pubs/ surveys/. 

Chao, C.M., Sheu, J.P., Chou, I-C., A load awareness medium access control protocol for wireless ad hoc network, IEEE International Conference on Communications, ICC 03, vol. 1, 11-15, pp. 438—442, May 2003. 

Fang, J.C. and KondyHs, G.D., A synchronous, reservation based medium access control protocol for multihop wireless networks, 2003 IEEE Wireless Communications and Networking, WCNC 2003, vol. 2, 16-20. March 2003, pp. 994-998. 

There are seven layers in the OSI model, starting with the physical layer handling the raw data transmission over a physical medium. The most common transmission media are twisted pair (copper wires), coaxial cable, and fiber optics. The data link layer, usually implemented in the network adaptors, is above the physical layer and is concerned with the organization of data into frames and the reliable transportation of these frames over a direct link. The specific problems of multi-access links such as channel allocation and collision detection are handled by the data link sub-layer called medium access control (MAC). Reliable frame delivery, frame ordering, and frame retransmission are provided in the layer by sliding window protocols. This is a set of protocols for full-duplex data frame transmission, in which the sender and the receiver both keep windows of frame acknowledgements and send frames only if a certain number of already sent frames were acknowledged by the receiver. The data link layer also includes some error detection and correction functions such as parity bit code and cyclic redundancy code (CRC). 

A ring topology was chosen instead of a bus topology to avoid medium access control or master/slave processing. A star topology would require more communieation ehannels than normally available on commercial microcontrollers. The Fig. 7 shows the connections and the paeket format. The Network Microcontroller creates the paeket with the proper header to inform channels about information required or operation to be performed. As the paeket is... 

Wei Y, John H, Estrin E D (2004) Medium access control with coordinated adaptive sleeping for wireless sensor networks. lEEE/ACM Trans. Networking 12 493-506... 

IEEE standard for information technology-telecommunications and information exchange between systems-local and metropolitan area networks-specific requirements—Part 11 Wireless LAN medium access control (MAC) and physical layer (PHY) specifications, IEEE Std 802.11-2012 (Revision of IEEE Std 802.11-2007), pp. 1-2793, Mar. 2012. 

Rajendran, V, Obiaczka, K., Garcia Luna Aceves, J. J. (2003). Energy efficient, collision free medium access control for wireless sensor networks. In Proceedings of SenSys 2003. ACM Press. doi 10.1145/958491.958513... 

Ye, W., Heidemann, J., Estrin, D. (2004). Medium access control with coordinated, adaptive sleeping forwireless sensor networks. lEEE/ACM Transactions on Networking, 72(3), 493-506. doi 10.1109/TNET.2004.828953... 

IEEE. (2003). 802.15.4 IEEE standardfor information technology— Telecommunications and information exchange between systems— Local and metropolitan area networks— Specific requirements part 15.4 Wireless medium access control (MAC) andphysical layer (PHY) specificationsfor low-rate wireless personal area networks (LR-WPANs). New York, NY The Institute of Electrical and Electronics Engineers, Inc. 

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