Recent advances in multi-hopping are extended to relay networks having multiple antennas and multiple sources. As for the single-antenna and single-source case, one can achieve the ergodic capacity of wireless relay networks with phase fading if the relays are in a region near the source terminal, and if phase information is available only locally. The capacity results further generalize to Rayleigh fading, single-bounce fading, certain quasistatic fading problems, cases where partial channel knowledge is available at the transmitters, and cases where local user cooperation is permitted. The multi-source networks considered are the multi-access and broadcast relay channels.