Non-coherent multi-user detection based on quantum search

3G and 4G mobile systems are based on CDMA technology. In order to increase the efficiency of CDMA receivers a 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 advent of 3G and 4G systems. We introduce a novel quantum computation based quantum multi-user detection (QMUD), employing Grover´s (see Bell Labs, April 1999)search algorithm, which provides optimal solution. The proposed algorithm is robust to any kind of noise/suboptimal solutions