A method for communicating in a network including a master and a set of slaves, wherein the communicating uses orthogonal frequency-division multiplexing OFDM and time division multiple access TDMA symbols on sub-carriers, comprising: broadcasting, from the master to the set of slaves using downlinks and all of the sub-carriers, a broadcast polling packet including data packets for each slave and sub-carrier assignments for the slaves; transmitting simultaneously, from each slave to the master using uplinks and the assigned sub-carriers, a response packet after receiving the broadcast polling packet; and broadcasting, from the master to the set of slaves using the downlinks and all of the sub-carriers, a group acknowledgement packet, indicating which slaves need to retransmit their response packet, wherein the broadcast polling packet, the response packet, and the group acknowledgement packet are included in one superframe in one communication cycle, and wherein the broadcasting on the downlinks and the transmitting on the uplinks are disjoint in time by separating downlink and uplink transmissions via time-division multiple access, wherein the broadcast polling packet further comprises a preamble composed of three OFDM and TDMA symbols, a physical layer control header and a payload, and wherein the physical layer control header further comprises master and slave status information, a bitmap field for indicating which slaves are requested to respond to the broadcast polling packet, and a power control indicator field, a transient message indicator field, whereby the transient message indicator indicates whether or not transient messages are included, the transient message enabling the master to send to a particular slave bulk data, control and configuration commands and other data which are too big to accommodate in the slave data portion of the polling packet, and a cyclic redundancy check. broadcasting, from the master to the set of slaves using downlinks and all of the sub-carriers, a broadcast polling packet including data packets for each slave and sub-carrier assignments for the slaves; transmitting simultaneously, from each slave to the master using uplinks and the assigned sub-carriers, a response packet after receiving the broadcast polling packet; and broadcasting, from the master to the set of slaves using the downlinks and all of the sub-carriers, a group acknowledgement packet, indicating which slaves need to retransmit their response packet, wherein the broadcast polling packet, the response packet, and the group acknowledgement packet are included in one superframe in one communication cycle, and wherein the broadcasting on the downlinks and the transmitting on the uplinks are disjoint in time by separating downlink and uplink transmissions via time-division multiple access, wherein the broadcast polling packet further comprises a preamble composed of three OFDM and TDMA symbols, a physical layer control header and a payload, and wherein the physical layer control header further comprises master and slave status information, a bitmap field for indicating which slaves are requested to respond to the broadcast polling packet, and a power control indicator field, a transient message indicator field, whereby the transient message indicator indicates whether or not transient messages are included, the transient message enabling the master to send to a particular slave bulk data, control and configuration commands and other data which are too big to accommodate in the slave data portion of the polling packet, and a cyclic redundancy check.