Hadi  Raheem Ali, Hussein  Lafta Atia, 
    A Survey on Unequal-Sized Clustering Based Routing Protocols for
Wireless Sensor Networks,
    Journal of Engineering and Applied Sciences,
    Volume 12,Issue 16,
    2017,
    Pages 4092-4101,
    ISSN 1816-949x,
    jeasci.2017.4092.4101,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2017.4092.4101)
    Abstract: Energy constraint is well known as a big issue in WSN applications since it affects their lifetime.
Therefore, to increase the lifetime of WSN, a wise method has to be adopted. So far, the clustering technique
has been shown to be efficient in inimizing energy dissipation and prolonging the network lifespan. This study
aims to illustrate unequal-sized clustering method, show why unequal-sized clustering emerged and review a
set of unequal-sized clustering routing protocols. In this survey, for each protocol studied, the attention is
mainly concentrated in the manner of cluster head selection, cluster formation and data routing techniques.
    Keywords: WSNs;network lifetime;unequal-sized clustering;single-hop routing;multi-hop routing;concentrated