Methods, systems, and apparatuses, including computer programs encoded on computer-readable media, for receiving a timing signal at a first access point, wherein the timing signal is also received at a second access point. A first time is synchronized at the first access point with a second time at the second access point based upon the received timing signal. The first access point is configured with a spreading code and a transmit frequency. The second access point is also configured with the spreading code and the transmit frequency. The spreading code of the first access point is synchronized with the spreading code of the second access point using the timing signal. A message is transmitted from the first access point to the node and from the second access point to the node.