Autocorrelation division multiple access systems (ADMA)

Summary form only given. ADMA is a new MIMO multiple access system that is designed for effectively eliminating interferences and hence opening new frontiers for wireless communication systems. A fundamental problem for signal processing is the separation two signals from their mixture. The problem would be simpler if they are non-overlapping in either time domain or frequency domain. The time division multiple access system (TDMA) explores the diversity in time and the frequency division multiple access system (FDMA) explores the diversity in frequency. Two signals may be overlapping in both time and frequency, but they still can be easily separated if they are uncorrelated (orthogonal). The code division multiple access system (CDMA) explores orthogonal property of the signal codes. It may be interesting to know that two signals may be overlapping in both the frequency and time domain and also are not orthogonal to each other, but they can still be separated if their autocorrelations are separable in the domain of time-lags. The autocorrelation division multiple access system (ADMA) explores the diversity of autocorrelation of signals. In a multiple access system, many users share the same communication channel and hence they interfere with each other. However, these interferences can be easily taken care of by using the orthogonal structure of the multiple access systems. The interferences that are difficult to deal with are the ones that are not coordinated with the multiple access system they are using. Examples of such interferences are those at the boundary of cells of a cellular mobile phone system. The (intentional) jamming signal is another example. The uncoordinated interference in unlicensed spectrum is the major road block for wireless communications. ADMA is an effective way to reduce the uncoordinated interferences. By a simulation study, the uncoordinated interference to signal ratio can be reduced from 100 times to 0.01 times in the same frequency b- andwidth. With such an interference-rejection capability, ADMA technology can make new frontiers for the wireless industry. In this presentation, we will show how the autocorrelation diversity can be explored to effectively reducing the uncoordinated inferences even when they are correlated with the signal. This includes the ADMA encoder, the ADMA filtering and the ADMA decoder. We will demonstrate that the ADMA filtering processing is noise invariant. In order to show the potential of ADMA, the spectrum efficiency of a mobile phone system is investigated. It can be shown by simulation that the spectrum efficiency can be improved by a factor of two without the need for channel estimation.