In order to better cope with the increasing levels of interference in wireless cellular systems, interference mitigation techniques that consider a certain degree of coordination/cooperation among cells have been recently employed, such as Joint Processing (JP) and Interference Alignment (IA). In this paper we evaluate the performance of different IA-based algorithms in the presence of uncoordinated external interference, with JP schemes used as a benchmark. Sum rate and Bit Error Rate (BER) results are presented for different external interference scenarios and it is shown that there is trade-off between IA and JP, and that for high external interference levels IA algorithms modified to handle this external interference can achieve better BER performances. Index Terms—Interference Alignment, Cooperative Precoding, External Interference.