Abstract: A Tree-structured multicarrier multiple access communication system in a multiple access environment having a number of interfering signals. In one embodiment an environment estimator estimates and tracks the number of interfering signals of the environment. A code selector determines an optimal spreading code represented by the environment, and identifies an actual spreading code that is closest to the optimal spreading code. A signal transmitter can then be used to transmit a multicarrier multiple access signals in accordance with the actual spreading code identified. On the receiver side, a multiuser detector (MUD) module performs tree structured multiuser detection signal processing, and produces a bit stream for each interfering signal.

Abstract: A digital wireless communication system for increasing the number of users capable of communicating over a network permits multiusers to transmit information simultaneously on the same channel or frequency. The primary example of such a system would be that employing radio frequency transmissions, even optical transmissions; however, the invention will also apply to magnetic detections such as in the reading of information stored on a magnetic tape. It is possible to increase overall throughput in terms of total number of bits transmitted through the shared medium by all users of a multiple access system if the signals are allowed to interfere. The present invention provides a multiuser detection process and apparatus that is capable of pulling apart signals in heavy interference in real time by combining the signals received from two or more spatially separated collectors or antennas.

Abstract: Techniques for reading data from a storage medium (150) having a high track density prone to adjacent track interference are disclosed. One or more sensing elements (120) are used to extract data stored on adjacent tracks. Multiuser detection (130) is then used to detect/decode a single track that is closely spaced to its neighboring tracks, resolve interference from adjacent tracks, or to simultaneously detect/decode multiple adjacent closely packed tracks.

Abstract: The present invention is a high quality real-time Turbo-Mud processing system initially employing a high complexity multi-user detector that results in better estimates of the bit streams, and then the remaining iterations employing a computationally low linear-based-MUD/Turbo-MUD. The present approach uses more computational computations at the first iteration, and less computations on subsequent processing due to cycling through the Turbo-Mud process with a low complexity sub-optimal detector that significantly cleans up the estimates in a few iterations of the Turbo-MUD. The present invention also provides an efficient means of estimating symbols transmitted in a multi-user environment in overloaded or super-saturated conditions.