Modern Roaming for Notes and Nomad – Cheaper Faster Better Stronger
Ieek fall Conference 2013
1. Cooperative Multi-Small Cells
with Imperfect CSIT
Toha Ardi Nugraha, Soo Young Shin
Department of IT Convergence
Kumoh National Institute of Technology
3. Introduction
• Cooperative communications are some cells that in a network
can work together
– ex. joint transmit power from many cells.
– To improve the system capacity
• Cooperative system can be impractical in realistic settings due
to perfect channel state information at the transmitter (CSIT),
• But sometimes, CSIT may not be available due to the channel
estimation problems
4. Cooperative Small-Cells
Small cell is generally implemented at home or
office areas,
Easily implemented on cooperative
communication scheme
connected via a high-speed optical fiber backbone to the gateway
5. Cooperative Small-Cells
C
N t nt ,1
(1)
i 1
N
N r nr ,1 (2)
u j 1
Example :
• Source Nt = 4
• Destination Nr = 2
1
H u j H u j ...
ℎ11 ℎ12 ℎ13 ℎ14
𝐻=
ℎ21 ℎ22 ℎ22 ℎ14
H uCj (3)
2𝑥4
6. ).
CSI Channel state information (CSI)
• Channel state information (CSI) refers to known channel
properties of a communication link.
Channel Estimation Problems
• A model for the Channel Estimation Problems:
– Example : a noiseless, error-free, and delay-free feedback channel.
7. Imperfect CSIT
C
Imperfect CSIT
C
yu j H w u H ui j
i 1
i
uj
*
H uj
i i
uj uj
u n u j , u n
CN(0, )
i 1
unu j ,un
e
H un H un
i i
wun uun
(5)
(6)
e
Error channel matrices
Power allocation for indoor propagation model
N
2
1
2 2
Pu j
Pc
(8)
Lossu j N
u j 1 Lossu j Lossu j
Pu *
j
uj
Ru j B *log 2 1
2
(9)
8. Simulation Setup
• Cooperative small cells with the number of
small cell = 3
– Max N_transmitter (Nt) = 2
– Max N_receiver (Nr) = 2
• Indoor Propagation Model : Cost 231 MWM
PLind 38.5 20log(d ) Lwalls
10. Conclusion
• This paper shows the impact of imperfect CSIT on the performance
of cooperative small cells with deterrent Nr and NT.
• A power allocation based on water-filling algorithm is also
implemented in this system.
• the cooperative cells at the networks that has imperfect CSIT show
bad performances compare to cooperative small cells with perfect
CSIT.
• The more number of Nt and Nr can maintains the system capacity
Future Works
• will be extended with the extended preceding algorithm