Distributed Interference Management Schemes: Femtocells
have limited knowledge about the global femtocell
network which makes the centralised techniques very difficult
to implement. Providing sufficient knowledge to the femtocells
is possible through the backhaul network, but this would cause
much congestion on the backhaul network. Furthermore, as
the number of femtocell can be very large, this makes it
impractical for the operator to provide large information to
the femtocell through the backhaul. In this case, distributed
schemes are of much importance. Researchers have provided
a number of distributed schemes for interference avoidance in
femtocells, some key techniques are discussed.
A distributed power control algorithm is proposed in [112].
for the closed access mode. The paper derives a relation which
provides the largest feasible cellular SINR values if a set of
feasible SINR values for femtocells are given. In order to
reduce the cross tier interference, a distributed utility based
SINR approach at the femtocell BS is also proposed, where the
power of femtocells causing strong interference is gradually
reduced [113]. A distributed dynamic Inter Cell Interference
(ICI) avoidance (DDIA) scheme is proposed in [114]. The
algorithm introduces the concept of ICI link and two tier
scheduling due to which it is able to harmonise all base
stations with users adaptively. An interesting study is done
in [115], where femtocells are able to decode the BS control
channel and make decisions related to transmission based
on the scheduling and resource allocation of the macrocell
system. The concept is similar to the Type II relays specified
in IEEE 802.16j standard. A number of comparisons are done
with certain system assumptions.
Distributed Interference Management Schemes: Femtocellshave limited knowledge about the global femtocellnetwork which makes the centralised techniques very difficultto implement. Providing sufficient knowledge to the femtocellsis possible through the backhaul network, but this would causemuch congestion on the backhaul network. Furthermore, asthe number of femtocell can be very large, this makes itimpractical for the operator to provide large information tothe femtocell through the backhaul. In this case, distributedschemes are of much importance. Researchers have provideda number of distributed schemes for interference avoidance infemtocells, some key techniques are discussed.A distributed power control algorithm is proposed in [112].for the closed access mode. The paper derives a relation whichprovides the largest feasible cellular SINR values if a set offeasible SINR values for femtocells are given. In order toreduce the cross tier interference, a distributed utility basedSINR approach at the femtocell BS is also proposed, where thepower of femtocells causing strong interference is graduallyreduced [113]. A distributed dynamic Inter Cell Interference(ICI) avoidance (DDIA) scheme is proposed in [114]. Thealgorithm introduces the concept of ICI link and two tierscheduling due to which it is able to harmonise all basestations with users adaptively. An interesting study is donein [115], where femtocells are able to decode the BS controlช่องและทำให้ตัดสินใจที่เกี่ยวข้องกับการส่งตามในการปันส่วนทรัพยากรและกำหนดการของการ macrocellระบบ แนวคิดจะคล้ายกับรีเลย์ชนิด II ที่ระบุใน 802.16j มาตรฐาน IEEE ทำตัวเลขเปรียบเทียบกับสมมติฐานบางระบบ
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