Method of polling second stations for functional quality and maintenance data in a discrete multitone spread spectrum communications system

DETAILED DESCRIPTION In accordance with this invention, a highly bandwidth-efficient method for transmitting and receiving information is implemented.
In one aspect of the invention, a plurality of multiple-access, bandwidth-efficient communication techniques are combined.
The invention is based, in part, on Applicants' realization that the distinct spectral and spatial analyses of received signals may be combined in a unified operation to extract each user's signal in a highly bandwidth-efficient multiple access system.
One aspect of the invention is a method of communicating signals from at least two different spatially separated remote transmitters to a receiving base station having a multi-element antenna array.
Each of the transmitters transmits signals representative of different information.
In accordance with this aspect of the invention, the mathematical representation of the spectral characteristics of the signals is capable of being put in a mathematical form that is substantially the same as the mathematical representation of the spatial characteristics of signals received by a multi-element antenna array.
This enables the receiver to efficiently process the received signals to simultaneously obtain adaptive spectral and spatial despreading and spreading weights that enhance the signal to noise and interference ratio of the signals.
The receiver can then identify the data associated with each of the signals transmitted by the transmitters and can forward that data to the respective recipients.
The term "spreading gains" can be used instead of "spreading weights", to emphasize the meaning that their values are adaptive and can vary in magnitude.
In another aspect of the invention, the spectral format of the signals is what we call discrete multitone stacked carrier (DMT-SC).
In this format, the user's data signal is modulated by a set of weighted discrete frequencies or tones.
The weights are spreading codes that distribute the data signal over a plurality of discrete tones covering a broad range of frequencies