Outsourcing the complexity of detection in MIMO channels

A noisy MIMO channel operating under a strict complexity constraint at the receiver is introduced. According to this constraint, detected bits, obtained by performing hard decisions directly on the channel's matched filter output must be the same as the transmitted binary inputs. In this simple detection scheme the complexity of detection is outsourced from the receiver back to the transmitter. Under a bounded noise assumption such complexity-constrained MIMO channel exhibits a non-trivial Shannon-theoretic capacity. It is shown that performance relies on rigorous interference-based multiantenna cooperation at the transmitter, and that the presence of a relay has a detrimental effect on the system performance bounds