1. Presented by: Vikram Shankar
Implementation of Multi-Level Multi-Access (MLMA) Medium Access Protocol on Mica2 Motes.
Presented by:
Vikram Shankar

2. Motivation
Energy-efficiency is of utmost importance in biosensor networks.
Two energy-efficient schemes, a cluster-based and a tree-based, were presented to address this problem[1].
Both schemes use TDMA in order to eliminate contention, an unnecessary waste of energy.
Both schemes require a subscription process.

3. Multi-Level Multi-Access MAC
Time is divided into decades (a frame of 10 slots).
During the first decade, nodes transmit a binary one during the slot that corresponds to its most significant digit. For example, if a node’s address is 765, it will transmit a bit during the slot corresponding to 7 in the first decade.
The next decade will be dedicated to servicing the next most significant digit of the nodes that had the highest most significant digit. This continues until all nodes are subscribed.
It is not a problem if more that one nodes transmit a bit during a slot.
The added advantage of this scheme is that every node knows which other node has joined the cluster. Thus, the order of joining the cluster can implicitly be used as the schedule of transmission in a TDMA frame.

4. An example 9 8 7 6 5 4 3 2 1 1 Nodes with addresses: 765, 439, and 743
Decade 1
Decade 2
Decade 3
Decade 4
Decade 5
Decade 6
Decade 7 1

5. References:
[1] V. Shankar, A. Natarajan, S.K.S. Gupta, L. Schwiebert, "Energy-efficient Protocols  for Wireless Communication in Biosensor Networks". In 12th IEEE International Symposium  on Personal, Indoor and Mobile Radio Communications, Volume: 1, Sept. 2001, Page(s):