Consider a Gaussian multiple-input multiple-output (MIMO) multiple-access channel (MAC) with channel matrix H and a Gaussian MIMO broadcast channel (BC) with channel matrix H⊺. For the MIMO MAC, the integer-forcing architecture consists of first decoding integer-linear combinations of the transmitted codewords, which are then solved for the original messages. For the MIMO BC, the integer-forcing architecture consists of pre-inverting the integer-linear combinations at the transmitter so that each receiver can obtain its desired codeword by decoding an integer-linear combination. In both cases, integer-forcing offers higher achievable rates than zero-forcing. In recent work, we established an uplink-downlink duality relationship for integer-forcing, i.e., we showed that any rate tuple that is achievable via integer-forcing on the MIMO MAC can be achieved via integer-forcing on the MIMO BC with the same sum power and vice versa. It has also been shown that integer-forcing for the MIMO MAC can be enhanced via successive cancellation. Here, we introduce dirty-paper integer-forcing for the MIMO BC and establish uplink-downlink duality with successive integer-forcing for the MIMO MAC.
['Wenbo He', 'Bobak Nazer', 'Shlomo Shamai']
Dirty-paper integer-forcing