Pilot decontamination in massive MIMO using Alternating Projection

Pilot contamination problem mainly comes from

the linearity of channel estimation algorithms, e.g. zero

forcing, and MMSE, which can be overcame by applying

nonlinear channel estimation algorithms. Therefore, the

alternating projection (AP) algorithm is back to our sights.

Since an AP based channel estimation uses the unknown

data symbols (blind) for channel estimation, the concern of

pilot contamination is vanished. This paper deals with AP

for Massive multi-input multi- output (MIMO) system with

focus on the channel estimation mean square error (MSE)

analysis. Through analytical results, we will show that

an AP based blind channel estimation is biased at

high signal to interference ratio (SIR) and tends to be

unbiased at low SIR. The reason of biasing is that it

estimates the channel and detects data for both the target

user and the interfering users simultaneously, so the higher

interfering power can benefit the detection performance.

Simulation results further confirm the results.

Keywords— Massive MIMO, Pilot contamination, Alternating

projection, Zero-forcing, MMSE

Elaborazione dati Matlab and Mathematica Senza Fili

Rif. progetto: #16274054

Info sul progetto