IEEE Conference on ICT Convergence, Jeju Island, South Korea 2013

1. IEEE International Conference on ICT Convergence 2013
Cooperative Water Filling (CoopWF) Algorithm
for Small Cell Networks
Toha Ardi Nugraha, Soo Young Shin
Department of IT Convergence, Kumoh National Institute of Technology
Abstract
This paper proposes a new power allocation algorithm with pre-coding in cooperative small cell networks (SCNs). A power allocation algorithm
based on cooperative water-filling (CoopWF) is proposed and block diagonalization (BD) precoding is adopted to cancel the inter-user interfere
nces. The proposed scheme is easily implementable to SCNs such as femto-cell, metro-cell, and pico-cell. Simulation results show that the propo
sed CoopWF algorithm provides better mean capacity compared to the existing power allocation algorithm.
Problem Statement
• Small cell network (SCN) such as femto-cell, metro-cell or pico-cell
is an effective solution for increasing the capacity of wireless
communication systems especially in the indoor public areas.
• SCN is generally implemented via a optical fiber backbone and
allows a reliable fast exchange of information among SCNs
• In SCN, a cooperative communication can be easily implemented.
• Cooperative communication is an effective strategy to mitigate
inter-cell interference and also it can dramatically improve the
system performance
Small Cell Network Architecture
The paper evaluate the performance o
f the cooperative small cells with the
number of C = 2 and 3 as shown in Fig.1
Objectives
• A power allocation algorithm based on cooperative water-filling
(CoopWF) is proposed and block diagonalization (BD) precoding
is adopted
• This paper propose cooperative power allocation algorithm with
BD precoding for small cell networks.
• The proposed algorithm is implemented and simulated in the
multi-user MIMO (MU-MIMO) SCN to measure the mean system
capacity.
Cooperative Water Filling
The number of antennas
at each small cell as trans
mitter Nt = 2 and each
user device as receiver is
equipped with Nr = 2 ant
ennas.
Simulation Result
• Cooperative communication can be represented by Multi-cell MI
MO system model as shown in Fig.1
• Several small cells having Nt transmit antennas and uj user equip
ment's (UEs) having Nr receive antennas.
• The two users are randomly located within the overlapping of the
cell edge zone (see Fig.1) with the radius of each small cell (R) is
20 meter.
• The indoor path-loss, for a small cell is modeled as a modified CO
ST-231 indoor propagation model.
• The received signal at the uj UE is given by
• The received signal for the user uj after BD is
When SNR is 0 dB, the mean capacity of our propose algorithm
with C=3 cells improved about 0.3 Mbps compare to the previ
ous algorithm with the same number of cooperative small cell
networks.
Conclusion
This paper proposes a power allocation algorithm with block diagonalization (BD) precoding in cooperative small cell networks. The proposed
scheme is easily implementable to small cell networks such as femtocell, metro-cell, and pico-cell. In our simulation result, we have shown that
the proposed algorithm could improve mean capacity. The simulation result is in line with the concept of water filling that improved spectral ef
ficiency on the low SNR. From the simulation result, when SNR is -10 dB until 0 dB, the mean capacity of our propose algorithm with C=3 cells in
creased about 0.4 Mbps compare to the previous algorithm with C=3 cells.
Kumoh National Institute of Technology
Wireless & Emerging Networking System Lab.