Performance of a Multiple Address RADA System

Potentialities and limitations are derived for a random access, discrete address (RADA) communication system in which addresses consist of time-frequency coded pulses and in which a higher order alphabet is realized by assigning many different addresses per person. The performance of such a multiple address RADA system is derived as a function of two parameters: the channel utilization and the size of the time-frequency matrix. The channel utilization is the ratio of the total information rate to the channel bandwidth. The size of the time-frequency matrix, in which addresses are formed, is a measure of the receiver complexity. If there is no limitation on matrix size, arbitrarily low probabilities of error can be obtained for any value of channel utilization below 70 percent by increasing the number of addresses per person. If both matrix size and channel utilization are fixed, a minimum error probability is achieved with an optimum number of addresses per person. The performance of a multiple address RADA system is shown to be generally superior to that of a single address ON-OFF RADA system.