US 5,933,421 AGranted

Method for frequency division duplex communications

AssigneeAT&T Wireless Services, Inc.

InventorsSiavash Alamouti, Eduardo F. Casas, Michael Hirano, Elliott Hoole, Mary Jesse, David G. Michelson, Patrick Poon, Gregory J. Veintimilla, Hongliang Zhang

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Abstract

The high quality PCS communications are enabled in environments where adjacent PCS service bands operate with out-of-band harmonics that would otherwise interfere with the system's operation. The highly bandwidth-efficient communications method combines a form of time division duplex (TDD), frequency division duplex (FDD), time division multiple access (TDMA), orthogonal frequency division multiplexing (OFDM), spatial diversity, and polarization diversity in various unique combinations. The method provides excellent fade resistance. The method enables changing a user's available bandwidth on demand by assigning additional TDMA slots during the user's session.

Claims41

Dependent claims

A highly bandwidth-efficient communications method, comprising the steps of:

receiving at the base station a first incoming wireless signal comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a first remote station during a first time division multiple access (TDMA) interval;
receiving at the base station a second incoming wireless signal comprising a plurality of second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a second remote station during said first time division multiple access (TDMA) interval;
receiving at the base station a third incoming wireless signal comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a third remote station during a second time division multiple access (TDMA) interval;
receiving at the base station a fourth incoming wireless signal comprising a plurality of said second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a fourth remote station during said second time division multiple access (TDMA) interval;
transmitting at the base station said first outgoing wireless signal comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said first remote station during a third time division multiple access (TDMA) interval;
transmitting at the base station said second outgoing wireless signal comprising a plurality of fourth discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said second remote station during said third time division multiple access (TDMA) interval;
transmitting at the base station said third outgoing wireless signal comprising said plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said third remote station during a fourth time division multiple access (TDMA) interval;
and
transmitting at the base station said fourth outgoing wireless signal comprising said plurality of said fourth discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said fourth remote station during said fourth time division multiple access (TDMA) interval.

6 more elements

A highly bandwidth-efficient communications method, comprising the steps of:

receiving at the base station a first incoming wireless signal comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a first remote station at a first geographic location during a first time division multiple access (TDMA) interval;
receiving at the base station a second incoming wireless signal comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a second remote station at a second geographic location during said first time division multiple access (TDMA) interval;
spatially despreading the first and second incoming signals received at the base station by using spatial despreading weights;
receiving at the base station a third incoming wireless signal comprising a plurality of second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a third remote station during said first time division multiple access (TDMA) interval;
receiving at the base station a fourth incoming wireless signal comprising a plurality of said second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a fourth remote station during said second time division multiple access (TDMA) interval;
spatially spreading a first and second outgoing wireless signals at the base station by using spatial spreading weights;
transmitting at the base station said first outgoing wireless signal comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said first remote station at said first geographic location during a third time division multiple access (TDMA) interval;
transmitting at the base station said second outgoing wireless signal comprising a plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said second remote station at said second geographic location during said third time division multiple access (TDMA) interval;
transmitting at the base station said third outgoing wireless signal comprising said plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said third remote station during a fourth time division multiple access (TDMA) interval;
and
transmitting at the base station said fourth outgoing wireless signal comprising said plurality of said fourth discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said fourth remote station location during said fourth time division multiple access (TDMA) interval.

8 more elements

A highly bandwidth-efficient communications method, comprising the steps of:

receiving at the base station a first incoming wireless signal polarized in a first polarization direction comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a first remote station during a first time division multiple access (TDMA) interval;
receiving at the base station a second incoming wireless signal polarized in a second polarization direction comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a second remote station during said first time division multiple access (TDMA) interval;
distinguishing the first and second incoming signals received at the base station by detecting said first and second polarization directions;
receiving at the base station a third incoming wireless signal comprising a plurality of second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a third remote station during said first time division multiple access (TDMA) interval;
receiving at the base station a fourth incoming wireless signal comprising a plurality of said second discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from a fourth remote station during said second time division multiple access (TDMA) interval;
forming a first and second outgoing wireless signals at the base station by polarizing them in said first and second polarization directions, respectively;
transmitting at the base station said first outgoing wireless signal polarized in said first polarization direction comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said first remote station at said first geographic location during a third time division multiple access (TDMA) interval;
transmitting at the base station said second outgoing wireless signal polarized in said second polarization direction comprising a plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said second remote station at said second geographic location during said third time division multiple access (TDMA) interval;
transmitting at the base station a third outgoing wireless signal comprising said plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said third remote station during a fourth time division multiple access (TDMA) interval;
and
transmitting at the base station a fourth outgoing wireless signal comprising said plurality of said fourth discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said fourth remote station location during said fourth time division multiple access (TDMA) interval.

8 more elements

A highly bandwidth-efficient communications method for improved fade resistance, comprising the steps of:

receiving at a base station a first incoming wireless signal bearing first data, the signal comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a first remote station during a first time division multiple access (TDMA) interval, said first signal having a first diversity receive path;
receiving at the base station a second incoming wireless signal bearing said first data, comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from said first remote station during said first time division multiple access (TDMA) interval, said second signal having a second diversity receive path that is highly uncorrelated with said first diversity receive path;
selecting at the base station said first diversity receive path for said first incoming wireless signal or selecting said second diversity receive path for said second incoming wireless signal to receive said first data;
generating at the base station a first outgoing wireless signal for transmission over a first diversity transmit path and generating a second outgoing wireless signal for transmission over a second diversity transmit path, said first diversity transmit path being highly uncorrelated with said second diversity transmit path;
transmitting at the base station said first outgoing wireless signal comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said first remote station over said first diversity transmit path during a third time division multiple access (TDMA) interval;
and
transmitting at the base station said second outgoing wireless signal comprising a plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said first remote station over said second diversity signal path during said third time division multiple access (TDMA) interval.

4 more elements

A highly bandwidth-efficient communications method for improved fade resistance, comprising the steps of:

receiving at a base station a first incoming wireless signal bearing first data, the signal comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a first remote station during a first time division multiple access (TDMA) interval, said first signal having a first diversity receive path;
receiving at the base station a second incoming wireless signal bearing said first data, comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from said first remote station during said first time division multiple access (TDMA) interval, said second signal having a second diversity receive path that is highly uncorrelated with said first diversity receive path;
selecting at the base station said first diversity receive path for said first incoming wireless signal or selecting said second diversity receive path for said second incoming wireless signal to receive said first data;
generating at the base station a first outgoing wireless signal and generating a second outgoing wireless signal;
transmitting at the base station said first outgoing wireless signal comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said first remote station during a third time division multiple access (TDMA) interval;
and
transmitting at the base station said second outgoing wireless signal comprising a plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said first remote station during said third time division multiple access (TDMA) interval.

4 more elements

A highly bandwidth-efficient communications method for improved fade resistance, comprising the steps of:

receiving at a remote station a first incoming wireless signal bearing first data, the signal comprising a plurality of first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a first frequency band from a base station during a first time division multiple access (TDMA) interval, said first signal having a first diversity receive path;
receiving at the remote station a second incoming wireless signal bearing said first data, comprising a plurality of said first discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said first frequency band from said base station during said first time division multiple access (TDMA) interval, said second signal having a second diversity receive path that is highly uncorrelated with said first diversity receive path;
selecting at the remote station said first diversity receive path for said first incoming wireless signal or selecting said second diversity receive path for said second incoming wireless signal to receive said first data;
generating at the remote station a first outgoing wireless signal and generating a second outgoing wireless signal;
transmitting at the remote station said first outgoing wireless signal comprising a plurality of third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in a second frequency band to said base station during a third time division multiple access (TDMA) interval;
and
transmitting at the remote station said second outgoing wireless signal comprising a plurality of said third discrete frequency tones that are orthogonal frequency division multiplexed (OFDM) in said second frequency band to said base station during said third time division multiple access (TDMA) interval.

4 more elements

Dependencies are inferred from the claim text.