  In vehicle-to-infrastructure (V2I) networks, a cluster of multi-antenna
access points (APs) can collaboratively conduct transmitter beamforming to
provide data services (e.g., eMBB or URLLC). The collaboration between APs
effectively forms a networked linear antenna-array with extra-large aperture
(i.e., network-ELAA), where the wireless channel exhibits spatial
nonstationarity. Major contribution of this work lies in the analysis of
beamforming gain and radio coverage for network-ELAA non-stationary Rician
channels considering the AP clustering. Assuming that: 1) the total
transmit-power is fixed and evenly distributed over APs, 2) the beam is formed
only based on the line-of-sight (LoS) path, it is found that the beamforming
gain is concave to the cluster size. The optimum size of the AP cluster varies
with respect to the user's location, channel uncertainty as well as data
services. A user located farther from the ELAA requires a larger cluster size.
URLLC is more sensitive to the channel uncertainty when comparing to eMBB, thus
requiring a larger cluster size to mitigate the channel fading effect and
extend the coverage. Finally, it is shown that the network-ELAA can offer
significant coverage extension (50% or more in most of cases) when comparing
with the single-AP scenario.
