Patent ID: 7551695
Filing Date: 2009-06-23
Classification: H04B

Abstract:
1. A method for verification of a bit vector which is transmitted from a mobile station to a base station that comprises two antennas and weighting factors (w 1 , w 2 ) for amplitudes and/or phases of the signals to be emitted from the antennas, wherein the transmitted bit vector is employed in the base station to determine the weighting factors, comprising: updating the bit vector in the mobile station by changing only one bit position in the bit vector at a time and transmitting the updated bit vector from the mobile station to the base station in the form of a bit, wherein the updated bit vector is associated with target weighting factors; transmitting current training symbols from the base station to the mobile station using updated weighting factors based on the updated bit vector received from the mobile station; and determining in the mobile station whether the updated weighting factors match the target weighting factors by evaluating the transmitted current training symbols from the base station and previously transmitted training symbols therefrom, where determining whether the updated weighting factors match the target weighting factor comprises: establishing a trellis diagram comprising possible states of the updated bit vector and possible state changes or branches between them; executing a Viterbi algorithm on the trellis diagram to determine the updated weighting factors being used by the base station; and comparing the updated weighting factors to the target weighting factors, where executing the Viterbi algorithm comprises: associating a cumulative metric with respective states; defining a branch metric as a function of the transmitted training symbols from the base station, wherein the branch metrics Δm where ( where h calculating a branch metric for respective branches of the trellis diagram that lead to a state; calculating a cumulative metric for respective states; determining the state with the largest cumulative metric; and selecting the weighting factors (w producing subsequent states on the basis of an initialization state in the trellis diagram in successive time steps until M state variables have been assigned respective cumulative metric values; calculating 2M subsequent states with cumulative metrics for the M state variables; sorting the 2M cumulative metrics on the basis of their magnitude; and assigning the M largest states to the M state variables and rejecting the remaining states such that they are no longer followed.