  Different from public 4G/5G networks that are dominated by downlink traffic,
emerging 5G non-public networks (NPNs) need to support significant uplink
traffic to enable emerging applications such as industrial Internet of things
(IIoT). The uplink-and-downlink spectrum sharing is becoming a viable solution
to enhance the uplink throughput of NPNs, which allows the NPNs to perform the
uplink transmission over the time-frequency resources configured for downlink
transmission in coexisting public networks. To deal with the severe
interference from the downlink public base station (BS) transmitter to the
coexisting uplink non-public BS receiver, we propose an adaptive asymmetric
successive interference cancellation (SIC) approach, in which the non-public BS
receiver is enabled to have the capability of decoding the downlink signals
transmitted from the public BS and successively cancelling them for
interference mitigation. In particular, this paper studies a basic
uplink-and-downlink spectrum sharing scenario when an uplink non-public BS and
a downlink public BS coexist in the same area, each communicating with multiple
users via orthogonal frequency-division multiple access (OFDMA). Under this
setup, we aim to maximize the common uplink throughput of all non-public users,
under the condition that the downlink throughput of each public user is above a
certain threshold. The decision variables include the subcarrier allocation and
user scheduling for both non-public (uplink) and public (downlink) BSs, the
decoding mode of the non-public BS over each subcarrier (i.e., with or without
SIC), as well as the rate and power control over subcarriers. Numerical results
show that the proposed adaptive asymmetric SIC design significantly improves
the common uplink throughput as compared to benchmark schemes without such
design.
