  This paper proposes novel joint channel estimation and beamforming approach
for multicell wideband massive multiple input multiple output (MIMO) systems.
Using our channel estimation and beamforming approach, we determine the number
of cells $N_c$ that can utilize the same time and frequency resource while
mitigating the effect of pilot contamination. The proposed approach exploits
the multipath characteristics of wideband channels. Specifically, when the
channel has $L$ multipath taps, it is shown that $N_c\leq L$ cells can reliably
estimate the channels of their user equipments (UEs) and perform beamforming
while mitigating the effect of pilot contamination. For example, in a long term
evolution (LTE) channel environment having delay spread $T_d=4.69\mu$ second
and channel bandwidth $B=2.5$MHz, we have found that $L=18$ cells can use this
band. In practice, $T_d$ is constant for a particular environment and carrier
frequency, and hence $L$ increases as the bandwidth increases. The proposed
channel estimation and beamforming design is linear, simple to implement and
significantly outperforms the existing designs, and is validated by extensive
simulations.
