Positive Operation Valued Measurement Based Multi-User Detection in   DS-CDMA Systems
  3G and 4G mobile are based on CDMA technology. In order to increase the effectiveness of CDMA receivers large amount of effort is invested to develop suitable multi-user detector techniques. However, at this moment there are only suboptimal solutions available because of the rather high complexity of optimal detectors. One of the possible receiver technologies can be the quantum assisted computing devices which allows high level parallelism in computation. The first commercial devices are estimated by 2004, which meets the advert of 3G and 4G systems. In this paper we introduce a novel quantum computation based Quantum Multi-user detection (QMUD) algorithm, employing simple Positive Operation Valued Measurement (POVM), which provides optimal solution. The proposed algorithm is robust to any kind of noise. 
S. Imre, F. Balazs