Martolia, Deepa
(2016)
On Improving Performance of Victim Macrocell Users in LTE HetNets with Closed Access Femtocells.
Masters thesis, Indian Institute of Technology Hyderabad.
Abstract
Todays wireless and cellular networks demand a minimum data rate requirements for its users, as
the users have apparently become dependent on mobile networks with the advent smartphones,
tablets, and other wireless gadgets. These high expectations from users have given rise in traf-
c demand. Cellular operators are also looking for solutions to eradicate the network issues like
call drops, choppy videos, and slow downloads. All of these trends will continue and have fuelled
the interest of researchers in wireless and cellular networks. In order to attain the high data de-
mand from users, operators are deploying new solutions in a coverage prone and highly populated
cell areas. 3rd Generation Partnership Project (3GPP) introduced Heterogeneous networks (Het-
Nets) in LTE-Advanced (Long Term Evolution - Advanced) for improving the experience of mobile
users. The HetNets launched new network topologies, which are cost-e ective and also improves
the data rate of mobile users. However, dense deployment of these new network nodes can also
bring a lot of challenges
i.e.,
interference control and management of new network nodes. Hence,
3GPP speci ed various interference mitigation technologies, which includes ICIC (Intercell inter-
ference coordination), Enhanced Intercell interference coordination (eICIC), and Further Enhanced
Intercell interference coordination (feICIC). In this thesis, we focus on the cross-tier interference
between Macrocell and Femtocell, and the performance enhancement of Victim Macrocell users. We
also proposed a centralized algorithm, which provides coordination between interfering Femtocell
(Closed Access Mode) and Macrocell, and o er a joint Almost Blank Subframe (ABSF) and power
control scheme for Femtocell muting. The two prime metric discussed in our thesis are;
a)
attuning
the transmission power during ABSF for Femtocell and then calculating the number of ABSF re-
quired, and
b)
determining appropriate subframes for muting an arbitrary Femtocell. Centralized
algorithm tracks the state of Macrocell users. A Macrocell user is referred as Victim Macrocell
user if the signal-to-interference-plus-noise ratio (SINR) value of Macrocell user degrades from the
required threshold value. In this work, we performed only Femtocell muting to show the e ect of
dense deployment of Femtocells on Macrocell users. During ABSF muting Femtocell automatically
adjusts its transmission power depending upon the level of interference su ered by Victim Macrocell
users, which also minimizes the unnecessary degradation in Femtocell users performance. In order
to increase the favorable chances of scheduling Victim Macrocell users during ABSF by its serving
Macrocell, the centralized algorithm mutes Femtocells in a round robin fashion and eradicates un-
necessary Femtocell muting. Our proposed scheme, RrMute compared with various other schemes
and the simulation results show that RrMute enhances the performance of Victim Macrocell users,
while simultaneously not jeopardizing the performance of Femtocell users.
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