LEACH

f1dec08_1GOAL:
1). Proposed LEACH (Low-Energy Adaptative Clustering Hierarchy)
2). Comparing LEACH with the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering


NOTE:

1). Microsensor networks can contain hundreds of thousands of sensing nodes. It is desirable to make these nodes as cheap and energy-efficient as possible and rely on their large numbers to obtain high quality result.
2). The authors consider microsensor networks where : a). The base station is fixed and located far from the sensors. b). All nodes in the networks are homogeneous and energy constrained.
3). Sensor networks contain too much data for an end-user to process. Therefore, automated methods of combining or aggregating the data into a small set of meaningful information is required.
4). The Key feature of LEACH :
a). Localized coordinator and control for cluster set-up and operation
b). Randomized rotation of the cluster “base stations” or “cluster-heads” and the corresponding clusters.
c). Local compression to reduce global communication.
5). Provide the model of energy loss due to channel transmission and receive the message
6). The authors make assumption that the radio channel is symmetric such that the energy required to transmit a message from node A to node B is the same as the energy required to transmit a message from node B to node A.
7). “Event-driven” simulation –> where sensors only transmit data if some event occurs in the environment.
8). The authors examine two such protocols : direct communication with the base station and minimum-energy multi-hop routing
9). Using a direct communication protocol, each sensor sends its data directly to the base station. If the base station is far away from the nodes, direct communication will require a large amount of transmit power from each node.
10).In  “Minimum-transmission-energy” (MTE) routing protocol, nodes route data destined ultimately for the base station through intermediate nodes. Thus nodes act as routers for other nodes’ data in addition to sensing the environment.
11). The paper provides equation for energy the direct communication approach and MTE routing
12). The authors using MATLAB for simulation
13). Most energy-efficient protocol to use depends on the network topology and radio parameters of the system
14). In MTE routing, the nodes closest to the base station will be used route a large number of data message to the base station. Thus these nodes will die out quickly.
15). In Direct Communication protocol, the nodes furtherst from the base station have the largest transmit energy .
16). In conventional clustering protocol, clustering appears to be an energy-efficient communication protocol. However, the local base station is assumed to be a high-energy node, if the base station is an energy-constrained node, it would die quickly.

LEACH:
1). It is a self-organizing, adaptive clustering protocol that uses randomization to distribute the energy load evenly among the sensors in the network. The nodes organize themselves into local clusters, with one node acting as the local base station or cluster-head.
2). LEACH includes randomized rotation of the high-energy cluster-head position such that it rotates among the various sensors in order to not drain the battery of a single sensor.
3). LEACH performs local data fusion to “compress” the amount of data being sent from the clusters to the base station.
4). In order to spread the energy usage over multiple nodes, the cluster-head nodes are not fixed.
5). The decision to become a cluster-head depends on the amount of energy left at the node.

LEACH Algorithm:
1). Advertisement Phase : Each node decides whether or not to become a cluster-head for the current round. Each node that has elected itself a cluster-head for the current round broadcasts an advertisement message to the rest of the nodes.
2). Cluster set-up Phase : Each node has decided to which cluster it belongs, it must inform the cluster-head node that it will be a member of the cluster.
3). Schedule creation : The cluster-head node creates a TDMA schedule telling each node when it can transmit.
4). Data transmission : The cluster-head node must keep its receiver on to receive all the data from the nodes in the cluster. When all the data has been received, the cluster head node performs signal processing functions to compress the data into a single signal. This composite signal is sent to the base station.
5). Multiple Cluster : To reduce interference transmission between clusters, each cluster communicates using different CDMA codes.

Source :

Energy-Efficient Communication Protocol for Wireless Microsensor Networks. By Wendi Rabiner Heinzelman, Anantha Chandrakasan, and Hari Balakrishan

Note : This resume is created for self-learning only. Author and Publisher hold copyrights

Improve your ability to focus on your research :)

Feb 18, 2009
Taipei City – High Speed Network Lab – Taiwan Tech (NTUST)
Electronics Engineering Polytechnic Institute of Surabaya (EEPIS)

Udin Harun

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