  In this paper, we consider a two-dimensional heterogeneous cellular network
scenario consisting of one base station (BS) and some mobile stations (MSs)
whose locations follow a Poisson point process (PPP). The MSs are equipped with
multiple radio access interfaces including a cellular access interface and at
least one short-range communication interface. We propose a nearest-neighbor
cooperation communication (NNCC) scheme by exploiting the short-range
communication between a MS and its nearest neighbor to collaborate on their
uplink transmissions. In the proposed cooperation scheme, a MS and its nearest
neighbor first exchange data by the short-range communication. Upon successful
decoding of the data from each other, they proceed to send their own data, as
well as the data received from the other to the BS respectively in orthogonal
time slots. The energy efficiency analysis for the proposed scheme is presented
based on the characteristics of the PPP and the Rayleigh fading channel.
Numerical results show that the NNCC scheme significantly improves the energy
efficiency compared to the conventional non-cooperative uplink transmissions.
