Nonlinear precoding method for a digital broadcast channel
First Claim
1. A nonlinear precoding method based on modulo arithmetic for the transmit-side preequalization of K user signals to be transmitted in a digital broadcast channel with known transmission channel matrix H set up between a central transmitting station and K decentralized, non-interconnected receiving stations, the user signals consisting of data symbols ak with k from 1 to K from a signal constellation having Mk·
- levels and a signal point spacing Ak·
with a periodic multiple representation of the undisturbedly-transmitted data symbols ak in data symbol intervals congruent for K receive-side modulo-decision devices, a transmit-power-minimizing selection of representatives vk from the range of values ak+Ak·
Mk·
zkk, where zkk is from the set of positive or negative integers including zero, and linear preequalization of the selected representatives vk to form transmit signals xk to be transmitted, comprising;
applying the nonlinear precoding method only to a reduced channel matrix Hred that is calculated from the equation H=Hred R, whereby H is the known channel matrix and R is a residual interference matrix indicating remaining interferences at the receive-side, the residual interference matrix containing interference elements chosen to assume a range of values Ak·
Mk zki, where zik is from the set of positive or negative integers including zero.
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Abstract
Several subscriber signals are transmitted simultaneously and at the same frequency by a central transmitter to several decentralized receivers which do not cooperate with each other, by digital message transmission in a broadcast channel. A common transmission signal, which enables an error-free individual reception, should be generated with knowledge of all subscriber signals and of the current transmission conditions, by signal preprocessing methods on the transmission side. Known nonlinear precoding methods totally suppress the interference signals, so that the channel diversity cannot be used. In the claimed precoding method, the occurring interference signals are, on the contrary, taken into account. On the basis of a modulo arithmetic calculation, the transmission channel is not totally equalized, but virtually divided, so that the transmission of the subscriber signals is continued periodically; the signals are selected according to the minimal transmission power and pre-equalized, in a linear manner, and the residual interferences, still remaining between the subscriber signals, may assume special values from a preset set of values. The set of values is selected, so that the interference signals of the other subscribers are also merely reflected in the otherwise already existing periodic continuation and can be suppressed or used as required by a modulo decision, on the reception side.
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Citations
3 Claims
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1. A nonlinear precoding method based on modulo arithmetic for the transmit-side preequalization of K user signals to be transmitted in a digital broadcast channel with known transmission channel matrix H set up between a central transmitting station and K decentralized, non-interconnected receiving stations, the user signals consisting of data symbols ak with k from 1 to K from a signal constellation having Mk·
- levels and a signal point spacing Ak·
with a periodic multiple representation of the undisturbedly-transmitted data symbols ak in data symbol intervals congruent for K receive-side modulo-decision devices, a transmit-power-minimizing selection of representatives vk from the range of values ak+Ak·
Mk·
zkk, where zkk is from the set of positive or negative integers including zero, and linear preequalization of the selected representatives vk to form transmit signals xk to be transmitted, comprising;applying the nonlinear precoding method only to a reduced channel matrix Hred that is calculated from the equation H=Hred R, whereby H is the known channel matrix and R is a residual interference matrix indicating remaining interferences at the receive-side, the residual interference matrix containing interference elements chosen to assume a range of values Ak·
Mk zki, where zik is from the set of positive or negative integers including zero. - View Dependent Claims (2, 3)
- levels and a signal point spacing Ak·
Specification