Coordinated multi-point (CoMP) processing is a key technique in next generation mobile communications. It can effectively solve the interference problem encountered in cell edges. To conduct the processing, however, base stations need to exchange users' informations, yielding a communication overhead for the backhaul. This paper considers inter-site uplink CoMP processing for multi-input-multi-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) systems. We first propose using the turbo equalization technique to improve the performance. In our scheme, the receiver consists of a soft MIMO equalizer and a soft channel decoder. The iteration is conducted between the equalizer and the decoder. With the inclusion of the exchanged informations in the iteration, the performance of the turbo equalization can be further improved. We then propose various exchanging strategies and find a good trade-off between performance gain and the required overhead. Compared with the optimum scheme, the proposed strategies can reduce the overhead significantly while the performance loss is small.