An interference cancellation scheme using dynamic space code multiple access (DSCMA) system

Non-uniform traffics can severely degrade the performance of code division multiple access (CDMA) and space division multiple access (SDMA) cellular systems. In this paper, we propose a novel interference cancellation scheme by using the joint multiple access system from the merge of CDMA and SDMA systems to form dynamic space code multiple access (DSCMA). This multiple access system uses a modified version of large area synchronous (LAS) sequence called LAS even-ternary (LAS-ET) sequence to increase its duty ratio. This sequence also exhibits a region called interference free window (IFW) near zero delay time offset. In order to ensure that all the signal components drop within the IFW, a narrow beam with higher directivity smart antenna system is exploited. The size of IFW is adapted to the smart antenna half-power beamwidth using DSC algorithm. By using this algorithm the spectrum efficiency is further increased. Finally, all the interferences induced in non-uniform traffics can be dramatically reduced in DSCMA system and thus resulting in a higher system capacity.