Phase-coherent TDMA quadrature receiver for multipath fading channels

Claim 2

A time division multiple access (TDMA) radio system receiver utilizing a synchronizing sequence in an assigned timeslot or message data to adapt a multi-phase demodulator to the finite impulse response of a radio channel during the assigned timeslot, comprising: means for correlating a first phase of a received synchronizing sequence to a predetermined sequence to produce a first correlator signal; means for correlating a second phase of said received synchronizing sequence to said predetermined sequence to produce a second correlator signal; and means for demodulating received message data into at least first phase data and second phase data by correlating a first phase of received message data and a second phase of received message data with said first correlator signal and said second correlator signal and combining the resulting outputs of correlation.

Claim 3

A time division multiple access (TDMA) radio system receiver in accordance with claim 1 wherein the synchronizing sequence further comprises a binary phase shift keying (BPSK) signal.

Claim 4

A time division multiple access (TDMA) radio system receiver in accordance with claim 1 wherein said means for demodulating further comprises: first means for correlating said first phase of received message data with said first correlator signal and said second correlator signal to produce first and second weighted signals, respectively; second means for correlating said second phase of received message data with said first correlator signal and said second correlator signal to produce third and fourth weighted signals, respectively; and means for adding said first and fourth weighted signals and for subtracting said second weighted signal from said third weighted signal.

Claim 5

A time division multiple access (TDMA) quadrature phase modulation receiver which receives a multipath-impaired signal from a radio channel, including a predetermined synchronizing signal portion and a multiphase data signal portion, comprising: means for orthogonally separating the received multipath-impaired signal into first and second intermediate signals; means for detecting the predetermined synchronizing signal portion from at least one of said first and second intermediate signals; means for obtaining first and second radio channel profiles of the radio channel from said detected synchronizing signal portion; and means for combining both said obtained radio channel profiles with the multiphase data signal portion of both said first and second intermediate signals to reconstruct phase coherent demodulated quadrature signals.

Claim 6

A time division multiple access (TDMA) quadrature phase modulation receiver which receives a multipath-impaired signal from a radio channel, including a predetermined synchronizing signal portion and a multiphase data signal portion, comprising: means for orthogonally separating the received multipath-impaired signal into first and second intermediate signals; means for detecting the predetermined synchronizing signal portion from at least one of said first and second intermediate signals; means for obtaining first and second radio channel profiles of the radio channel from said detected synchronizing signal portion; and means for combining both said obtained radio channel profiles with the multiphase data signal portion of both said first and second intermediate signals to reconstruct phase coherent demodulated quadrature signals.

Claim 7

A time division multiple access (TDMA) quadrature phase modulation receiver in accordance with claim 4 wherein the synchronizing signal portion further comprises a binary phase shift keying (BPSK) signal.

Claim 8

A time division multiple access (TDMA) radio receiver demodulator which demodulates from a radio channel a multipath-impaired quadrature phase shift keying (QPSK) data signal including a predetermined acquisition sequence and a message in a TDMA timeslot, the radio receiver demodulator comprising: means for separating a received data signal into quadrature phase components; means for detecting the predetermined acquisition sequence from said quadrature phase components of said received data signal; means, responsive to said detected acquisition sequence, for synthesizing at least one multipath profile of the radio channel for each quadrature phase component of the received data signal; means, responsive to each multipath profile, for performing multipath correlation of the message in each quadrature phase component to produce pairs of a multipath correlated message for each quadrature phase component; and means for summing mutually exclusive pairs of said multipath correlated message.

Claim 9

A time division multiple access (TDMA) radio receiver demodulator which demodulates from a radio channel a multipath-impaired quadrature phase shift keying (QPSK) data signal including a predetermined acquisition sequence and a message in a TDMA timeslot, the radio receiver demodulator comprising: means for separating a received data signal into quadrature phase components; means for detecting the predetermined acquisition sequence from said quadrature phase components of said received data signal; means, responsive to said detected acquisition sequence, for synthesizing at least one multipath profile of the radio channel for each quadrature phase component of the received data signal; means, responsive to each multipath profile, for performing multipath correlation of the message in each quadrature phase component to produce pairs of a multipath correlated message for each quadrature phase component; and means for summing mutually exclusive pairs of said multipath correlated message.

Claim 10

A time division multiple access (TDMA) radio receiver demodulator in accordance with claim 6 wherein the predetermined acquisition sequence further comprises a binary phase shift keying (BPSK) signal.

Claim 11

A digital radio receiver which receives and demodulates a time division multi-phase modulated data signal having multiple copies introduced by multipath signal interference on a radio channel, the data signal having a synchronizing signal portion and a message signal portion, the digital radio receiver comprising: (a) means for separating a received data signal into first and second intermediate signals, each said first and second intermediate signal having a synchronizing signal portion and a message signal portion; (b) means for detecting a received synchronizing signal, further comprising: (1) means for correlating said first intermediate signal synchronizing signal portion to a predetermined signal to produce a first correlator signal, and (2) means for correlating said second intermediate signal synchronizing signal portion to said predetermined signal to produce a second correlator signal; and (c) means for demodulating a received message signal with the multiple copies compensated, further comprising: (1) means for correlating said first intermediate signal message signal portion with said first correlator signal to produce a first weighted signal, (2) means for correlating said first intermediate signal message signal portion with said second correlator signal to produce a second weighted signal, (3) means for correlating said second intermediate signal message signal portion with said first correlator signal to produce a third weighted signal, (4) means for correlating said second intermediate signal message signal portion with said second correlator signal to produce a fourth weighted signal, (5) means for adding said first weighted signal and said fourth weighted signal to produce a demodulated first phase of the multi-phase modulated signal, and (6) means for subtracting said second weighted signal from said third weighted signal to produce a demodulated second phase of the multi-phase modulated signal.

Claim 12

A digital radio receiver which receives and demodulates a time division multi-phase modulated data signal having multiple copies introduced by multipath signal interference on a radio channel, the data signal having a synchronizing signal portion and a message signal portion, the digital radio receiver comprising: (a) means for separating a received data signal into first and second intermediate signals, each said first and second intermediate signal having a synchronizing signal portion and a message signal portion; (b) means for detecting a received synchronizing signal, further comprising: (1) means for correlating said first intermediate signal synchronizing signal portion to a predetermined signal to produce a first correlator signal, and (2) means for correlating said second intermediate signal synchronizing signal portion to said predetermined signal to produce a second correlator signal; and (c) means for demodulating a received message signal with the multiple copies compensated, further comprising: (1) means for correlating said first intermediate signal message signal portion with said first correlator signal to produce a first weighted signal, (2) means for correlating said first intermediate signal message signal portion with said second correlator signal to produce a second weighted signal, (3) means for correlating said second intermediate signal message signal portion with said first correlator signal to produce a third weighted signal, (4) means for correlating said second intermediate signal message signal portion with said second correlator signal to produce a fourth weighted signal, (5) means for adding said first weighted signal and said fourth weighted signal to produce a demodulated first phase of the multi-phase modulated signal, and (6) means for subtracting said second weighted signal from said third weighted signal to produce a demodulated second phase of the multi-phase modulated signal.

Claim 13

A digital radio receiver in accordance with claim 8 wherein the synchronizing signal portion further comprises a binary phase shift keying (BPSK) signal.

Claim 16

A method in accordance with the method of claim 10 wherein said demodulating step further comprises the steps of: correlating said first phase of received message data with said first correlator signal and said second correlator signal to produce first and second weighted signals, respectively; correlating said second phase of received message data with said first correlator signal and said second correlator signal to produce third and fourth weighted signals, respectively; and adding said first and fourth weighted signals and subtracting said second weighted signal from said third weighted signal.