SNRs, this is asymptotically equivalent to ZFcoop. MMSEcoopSIC. This is the same as MMSEcoop, but, in addition, nonlin- ear interference cancellation (uplink) or dirty paper coding (downlink) is performed. © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology The purpose of this simulation is a qualitative comparison between some coop- erative and noncooperative transmission strategies. It demonstrates that the theo- retical gain by BS cooperation can be huge, depending on the SNR range and the degree of cooperation. Although the basic simulation parameters were chosen according to the LTE specifications, the simulation is not meant to replace a full LTE system-level simulation, and important aspects, like scheduling or frequency diversity, are not included. Therefore, the resulting SINR values are rather low. We are mainly interested in the differences between the curves. It can be observed that, if full cooperation is possible, the system is no longer interference limited. For the case of MMSEcoopSIC, this even holds for an arbi- trarily large number of users. This has an interesting consequence because it means that no matter how many users there are and how large their requested SINR is, it can always be supported as long as the power constraints are not violated. The cooperative system (MFcoop, ZFcoop, MMSEcoop, MMSEcoopSIC) is not inter- ference limited, whereas conventional noncooperative systems are interference lim- ited (like SD, MRC, and MMSE). That is, the interference puts a hard limit on the achievable SINR. Increasing the transmit power does not help in this case because the interference is increased. Finally, note that MMSE and MRC perform almost the same. This is explained by the large number of interferers; thus, the resulting interference is similar to isotropic noise. 7.3 Classification of Cooperation Schemes Cooperative antenna systems may be implemented in many different ways; the fol- lowing is a short classification of the most important COOPA pr