  With the fast growing number of wireless devices and demand of user data, the
backhaul load becomes a bottleneck in wireless networks. Physical layer network
coding (PNC) allows Access Points (APs) to relay compressed, network coded user
data, therefore reducing the backhaul traffic. In this paper, an implementation
of uplink Network Coded Modulation (NetCoM) with PNC is presented. A 5-node
prototype NetCoM system is established using Universal Software Radio
Peripherals (USRPs) and a practical PNC scheme designed for binary systems is
utilised. An orthogonal frequency division multiplexing (OFDM) waveform
implementation and the practical challenges (e.g. device synchronisation and
clock drift) of applying OFDM to NetCoM are discussed. To the best of our
knowledge this is the first PNC implementation in an uplink scenario in radio
access networks and our prototype provides an industrially-applicable
implementation of the proposed NetCoM with PNC approach.
