Avoiding stall conditions and sequence number ambiguity in an automatic repeat request protocol

A method for use in data unit transmissions between a transmitter and a receiver implemented in the receiver, comprising:

• detecting a sequence number of data units received by the receiver;
• storing the received data units in a buffer;
• identifying a missing data unit in the sequence;
• determining whether a stall condition exists with respect to receiving the missing data unit;
• and
• when the stall condition exists, removing from the buffer the received data units having sequence numbers less than the sequence number of the missing data unit.

A method for use in data unit transmissions between a transmitter and a receiver implemented in the transmitter, where each data unit includes a corresponding sequence number, comprising:

• transmitting data units in sequence modulo-N, N being a largest sequence number;
• establishing a retransmission window having a size corresponding to a number of data units less than N;
• and
• using the retransmission window to avoid sequence number ambiguity in the receiver between originally-transmitted data units and retransmitted data units.

A receiver for receiving data units transmitted from a transmitter, comprising:

• a detector for detecting a sequence number of data units received by the receiver;
• a buffer for storing the received data units in a buffer;
• a timer;
• and
• electronic circuitry configured to:
• identify a missing data unit in the sequence;
• start the timer if a data unit is received having a sequence number greater than a sequence number of the missing data unit;
• and
• if the timer expires before the missing data unit is received, remove from the buffer the received data units having sequence numbers less than the sequence number of the missing data unit.

A transmitter for use in transmitting data units to a receiver, where each data unit includes a corresponding sequence number, comprising:

• a transmitter for transmitting data units in sequence modulo-N, N being a largest sequence number;
• a retransmission window having a size corresponding to a number of data units less than N;
• and
• a controller configured to use the retransmission window to avoid sequence number ambiguity in the receiver between originally-transmitted data units and retransmitted data units.