Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $E^2$-MAC: Energy Efficient Medium Access for Massive M2M Communications   In this paper, we investigate energy-efficient clustering and medium access
control (MAC) for cellular-based M2M networks to minimize device energy
consumption and prolong network battery lifetime. First, we present an accurate
energy consumption model that considers both static and dynamic energy
consumptions, and utilize this model to derive the network lifetime. Second, we
find the cluster size to maximize the network lifetime and develop an
energy-efficient cluster-head selection scheme. Furthermore, we find feasible
regions where clustering is beneficial in enhancing network lifetime. We
further investigate communications protocols for both intra- and inter-cluster
communications. While inter-cluster communications use conventional cellular
access schemes, we develop an energy-efficient and load-adaptive multiple
access scheme, called n-phase CSMA/CA, which provides a tunable tradeoff
between energy efficiency, delay, and spectral efficiency of the network. The
simulation results show that the proposed clustering, cluster-head selection,
and communications protocol design outperform the others in energy saving and
significantly prolong the lifetimes of both individual nodes and the whole M2M
network.

17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom