Method and apparatus for interference cancellation and adaptive equalisation in diversity reception

Claim 1

An interference cancellation apparatus for use in combination with a diversity receiving system which has first and second diversity routes, said apparatus being supplied with first and) second diversity reception signals (1) and (2) corresponding to said first and said) second diversity routes and being operable as a decision feedback equalizer to produce an equalized signal, said apparatus comprising: first and second transversal filter means (101 and 102) which have a plurality of first and second taps, said first and said second transversal filter means (101 and 102) filtering said first and said second diversity reception signals (1 and 2) into first and second transversal filtered signals (Sr₁ and Sf₂) in accordance with first and second controllable tap gains, respectively; first and second control means (103 and 104) for controlling said first and said second controllable tap gains with reference to a first error signal (ε₁) and a distributed signal distributed in each one of said first and said second taps in accordance with a predetermined adaptive algorithm; third transversal filter means (105) which has a plurality of third taps and which filters a decision signal (S d ) into a third transversal filtered signal (S b ) in accordance with third controllable tap gains; third control means (106) for controlling said third controllable tap gains with reference to said first error signal (ε₁) and a third distributed signal distributed in each of said third taps in accordance with said predetermined adaptive algorithm; decision means (107) for detecting a level of said equalized signal to decide a decision level for said equalized signal and to produce a decision signal (S d ) representative of said decision level to supply said decision signal (S d ) to said third transversal filter means (105); first error producing means (109) for producing said first error signal (ε₁) indicative of a difference between a subtracted signal (S r ) and said decision signal (S d ), said first error signal (ε₁) being supplied to said first, said second and said third control means (103, 104 and 106); subtractor means (110) for subtracting said third transversal filtered signal (S b ) from a combined signal (S p ) to supply said subtracted signal (S r ) to said decision means (107) and said first error producing means (109); and diversity combining means (158) for combining said first and said second transversal filtered signals (Sf₁ and Sf₂) to produce said combined signal (S p ); characterized in that: said diversity combining means (158) includes: adder means (108) for calculating a total sum of a first complex multiplied signal (Sc₁) and a second complex multiplied signal (Sc₂) to produce a total sum signal as said combined signal (S p ) representative of said total sum; first and second complex multiplier means (112 and 113) for complexly multiplying said first and said second transversal filtered signals (Sf₁ and Sf₂) by first and second correlated values α and β to produce said first and said second complex multiplied signals (Sc₁ and Sc₂), respectively; first and second correlation means (114 and 115) for correlating said first and said second transversal filtered signals (Sf₁ and Sf₂) with a second error signal (ε₂) in each of said first and said second diversity routes to produce first and second correlation signals indicative of said first and said second correlated values α and β, respectively; and second error producing means (111) for producing said second error signal (ε₂) indicative of a difference between said total sum signal (S p ) and said decision signal (S d ), said second error signal (ε₂) being supplied to said first and said second correlation means (114 and 115), respectively.