Abstract: A method for communication in a sequence of frames includes assigning a respective time slot to each of a plurality of mobile units, while reserving an unassigned time slot. During a first frame, one of the mobile units transmits an uplink signal in the respective time slot, carrying first uplink data over the air to a base station. The base station transmits a downlink signal to the mobile unit indicating that retransmission of the first uplink data is required. Responsively to the downlink signal, during a second frame subsequent to the first frame, the mobile unit transmits the uplink signal both in the respective time slot and in the reserved time slot so as to carry the first uplink data and second uplink data over the air to the base station. A similar method may be used for downlink retransmission.

Abstract: A phase generator includes at least one input port for accepting a reference signal having a frequency, a plurality of n output ports, n>4, and a network of phase-shifting elements coupled in a circularly-symmetrical configuration between the at least one input port and the output ports. The network of phase-shifting elements has a symmetry increment of 360/n degrees. The phase generator generates at the output ports respective polyphase signals at the frequency, the polyphase signals having respective phases that are consecutive integer multiples of 360/n degrees.