Abstract: In an orthogonal frequency division multiplex (OFDM) communication network, a node transmits an echo profile probe to other nodes in the network. The echo profile probe is a message that allows characterization of the unique echo profile through the communication channel between each node pair. The echo profile is used to calculate the cyclic prefix length needed for optimum communication from one node to the other.

Abstract: An efficient algorithm is described for use with OFDM receivers that characterizes the impulse response of a communication channel using frequency domain techniques that reduce computational and memory requirements, relative to time-domain cross-correlation methods, without sacrificing algorithm performance. An FFT engine is used to transform a time domain input sequence, the transformed sequence is multiplied by the conjugate of the expected sequence, the product of several sequences is averaged, then the FFT engine transforms the average back to a time domain sequence, the magnitude of which is the impulse response of the channel.

Abstract: A radio conferencing method and apparatus for transmitting packets of data from a plurality of radios over a transmission channel within a series of frames of predetermined duration, each packet of data having a predetermined time length, which method comprises the steps of: sensing the status of the channel; if the channel is idle, then transmitting the packet of data; if the channel is busy with another packet of data being sent, then disposing the packet of data and re-scheduling the transmission of the next packet of data to a time equal to a fraction of the time length of the packet of data plus the duration of the frame; and repeating the above steps.