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In recent years, smart antenna technologies are of ever-increasing interest to boost the capacity of future wireless systems. Several standards support these techniques such as the wireless metropolitan area network IEEE 802.16 (WiMAX) and IMT-Advanced candidates. In applying smart antenna beamforming and Space Division Multiple Access (SDMA) techniques, adaptive antennas are able to increase cell capacity by reducing inter-cell interference and by allowing concurrent transmissions. As a downside, an SDMA enabled cell generates less predictable interference than a conventional cell, because a changing number of mobile stations (MS) are sending uplink data in parallel and downlink streams with changing direction are transmitted by the base station (BS). Thereby the SINR estimation becomes less precise and the link adaptation sub optimal. This work investigates schemes of coordination, across BSs on MAC layer, for highly variable traffic for further mitigation of inter-cell interference and increasing precision of SINR estimations in an SDMA enhanced system. One concept considers the coordination of regions instead of single stations. The developed concepts are evaluated in a cellular deployment by means of system-level simulations for up- and downlink. The performance of a coordinated system is compared with a non-coordinated reference case and with simple coordination schemes of former work.