Abstract: Methods and systems for obtaining improved channel estimates for frequency-multiplexed data transmissions such as OFDM, OFDMA, or SC-FDMA transmissions overcome the limitations of the static assumption by using a polynomial or other fitting function to fit and model the frequency dependence of the channel coefficients, so that estimates can be applied to larger subcarrier groups. Some embodiments provide channel estimates for a singular signal source, while other embodiments provide joint channel estimates for a plurality of signal sources. In embodiments, selection of the fitting functions is influenced by all previously determined channel estimates. In some embodiments, a tracking algorithm allows use of the lowest possible order of polynomial or other fitting function to model the frequency dependence of the channel coefficients, whereby the channel estimate is continually shifted in frequency while the order of the polynomial or other fitting function remains low.

Abstract: A method of providing medium access control for a wireless mobile ad hoc network includes defining a TDMA network timing frame including a data (DATA) zone having one or more time slots structured to support multiuser detection (MUD) of concurrent transmissions during each slot, a negative acknowledgment (NACK) zone during which nodes transmit requests for retransmission of packets destined to but not successfully received by the nodes, a broadcast (BC) zone during which network management messages are broadcast to the nodes, and a control (CTRL) zone. A primary master (PM) node is selected and operates as a source of network time for all the nodes. Each node synchronizes its time to that of the PM node during the CTRL zone in a distributed manner, by exchanging control messages with the PM node or other nodes located one or more hops from the PM node.