A multiple access for unlicensed spectrum

The current multiple accesses, such as CDMA, are designed for multi-user wireless communication systems in the licensed spectrum, where uncoordinated interferences can be kept to a minimum. On the other hand, the uncoordinated interferences do exist in the unlicensed spectrum, and they compromise the orthogonal properties and hence degrade the performance of the current multiple accesses. In this presentation, the Autocorrelation-Division Multiple Access (ADMA) is presented, which achieves the best SINR among all passive pre-/post-filters, by eliminating all MAI and CCI, and retaining the signal power when the channel is lossless without enhancing the noise power.