EurOCEAN 2000 - Vlaams Instituut voor de Zee

Apart from suffering from ISI, a multi-user network also suffers interference from other
acoustic modems, or commonly known as Multiple Access Interference (MAI). Several types
of MAI cancellation schemes have been devised over the years, this report reviews a number of
the MAI cancellation schemes.
The multi-element single-user (MESU) decision-feedback (DFE) receiver has been shown to
effectively combat multipath fading and ISI problems. In a network scenario, apart from ISI,
the receiver suffers also from Multiple-Access Interference (MAI) from other users.
Conventional communication network (as in the case for CDMA) employs a bank of matched
filters to act as an optimum multi-user detector, that decodes each user’s signal. More recently,
several types of MAI cancellation schemes were introduced. The Multi-Element Multi-User
(MEMU) DFE uses the “crossover” feedback filters to cancel out user’s interference. Another
type of MAI cancellation proposed for radio communication, employs a multistage decoding.
The decision directed equalization algorithms generally gave a bit detection error of (Pe