Idea

  • Existing systems employ sparse pulses
    which can be transmitted and detected by rather simple circuitry. Some people say it is fast enough. But others may not be satisfied.
  • Another kind of systems employ a set of mutually orthogonal pulses
    which can be detected individually by virtue of the orthogonality even though they are overlapping and mixed with one another. A major advantage is that we can adaptively change the set of pulses in accordance with the channel characteristics. But tranceivers will be highly complicated while the transmission rate will not be drastically improved because those pulses occupy a long time slot.
  • The present system employs a train of orthogonal overlapping pulses
    of the same shape. The highly dense pulses will implement very fast communications.
    • The pulse belongs to system-theoretic generalization of splines, which can be shaped easily through an ordinary analog filter excited by a staircase function.
    The received pulses (mixed with one another) can be detected individually as correlations with the template pulses. The correlators will raise the cost of receiver circuitry. More correlators may have to be deployed in order to cope with multipath effects. The cost, however, should be justified since there would be no faster communications without denser pulses in the first place.