Coalition Network Elements (CNE) are proposed for Base Stations (BS) cooperation, where the CNEs carry traffic for the BS in support of its cell-edge MSs by exploiting the unused frequency bands of the BS network, while considering a range of practical impairments. We derive the coalition probability by taking into account both system loads of the primary network as well as the CNE's greediness. Our simulation results demonstrate that the proposed solution is capable of substantially increasing the attainable SINR in a wide range of scenarios and it is also robust to diverse practical imperfections.