Tomlinson Harashima precoding with additional receiver processing in a multi-user multiple-input multiple-output wireless transmission system

A base station (BS) in a multi-user multiple-input multiple-output (MU-MIMO) wireless system which also includes a plurality of K user terminals (UEs) which communicate with the base station via an uplink (UL) channel and a corresponding downlink (DL) channel, and a DL channel matrix representing the DL channel through which communications occur in the wireless system with the user terminals, the BS comprising:

• N antennas and Pt as available transmit power;
• and
• a Tomlinson Harashima precoder configured to process user symbols to produce an output of filtered vectors symbols for the UEs, which is to be transmitted to the channel;
• wherein the Tomlinson Harashima precoder includes an interference pre-cancellation matrix B for an interference pre-cancellation block and a transmit filter matrix F for a transmit filter, and the Tomlinson Harashima precoder is configured to estimate a DL channel matrix Hk for each of the K UEs;
• determine a receiver processing matrix Vk for each of the K UEs;
• compute, based on the DL channel matrix Hk and the receiver processing matrix Vk, an effective DL channel matrix Heff;
• perform a QR decomposition (QRD) of the effective DL channel matrix Heff, with column pivoting in which Q is a unitary matrix and R is an upper triangular matrix;
• and use the unitary matrix Q and the upper triangular matrix R to calculate B and F;
• and
• wherein the receiver processing matrix Vk is provided to the UEs by the BS to be used for performing additional receiver processing on the transmitted signals at the UEs, and scalar weights calculated based on the upper triangular matrix R are provided to the UEs for scaling down the output of filtered vector symbols from the Tomlinson Harashima precoder.