  Underlaying the cellular networks, Device to Device (D2D) communication
brings the possibility to significantly improve the spectral efficiency in
cellular networks and offload the traffic relayed by the base station. However,
it creates new challenge for interference management as well. In this paper, we
consider the multi-cell D2D underlaid cellular network in which many D2D links
reuse the uplink resource simultaneously. The infeasibility of interference
cancellation/alignment motivates us to force the D2D users near the base
stations to work in cellular mode. Based on that, we present a distributed and
scalable mode selection scheme based on guard zone to make a good tradeoff
between decreasing interference penalty to base stations and improving spectrum
utilization. With the help of stochastic geometry, we develop an analytically
tractable framework to analyze the interference and then throughput for the two
kinds of users in the considered scenario. The results obtained by the
framework reveal that enabling D2D communication does improve the per user
throughput and that a proper guard zone can further significantly increase the
average throughput of both kinds of users. Thanks to the tractability of our
model, the optimal guard zone, which is the key parameter in our scheme, can be
efficiently obtained by finding the root of the first order derivative of the
throughput expression. Through extensive numerical analysis, we show insights
of the system and give some guidelines in system design aspect.
