Abstract: A new method of multi-user BC unicast and BC multicast coexistence was proposed,and a new method of zero-space interference was proposed.The main network of the model uses “loop mode” to allocate the expected message to the receiving end to form the multicast network.The secondary network uses the “one-over-one” to allocate the desired message to the receiving end to constitute an unicast network.The forcing zero method first obtains the corresponding zero space according to the interference message of the receiving end,and then takes a number of intersection space of zero space.Finally,multiple interference messages are placed in the corresponding intersection space at the same time,achieving more than one forcing zero interference message at each receiving end.For this multiuser system,the generalized results of optimized antenna configuration scheme and thereuse gain of the system are obtained.The system was simulated through Matlab.The results show that the theoretical value of the system reuse gain is consistent with the simulation results.

Key words: Broadcast channel, Multicast, Nullspace intersection, Space reuse gain, Unicast, Zero forcing