Enhanced recovery procedure

A receiver entity adapted for receiving on a given channel and acknowledging the reception of packet data units from a transmitter entity according to an automatic repeat request process,

• the receiver entity comprising a decoding unit, automatic repeat request Processors, reordering and re-assembly queues, an upper protocol layer, and a receiver entity feedback processor;
• wherein the reception is being based on in-sequence delivery of packet data units from a first protocol layer to a higher protocol layer in the receiver entity,
• the receiver entity comprising a receiver window of fixed size stored in the reordering and re-assembly queue, the receiver window pertaining to a sequence of packet data units to be received;
• the receiver window being defined as the interval of sequence numbers ranging from the highest received sequence number minus the receiver window size plus one to the highest received sequence number;
• and wherein a next expected sequence number is registered reflecting the next sequence number to be delivered to the higher protocol layer in order to maintain the in-sequence delivery;
• the receiver entity comprising a control message handler being adapted to carry out the steps of:
• monitoring whether the identity of the receiver entity can be decoded for an incoming packet data unit;
• monitoring whether an automatic repeat request process is decoded correctly for the incoming packet data unit;
• and if so, reading the transmit sequence number of the incoming packet data unit;
• performing:
• a normal reordering procedure, in which a received packet having a sequence number corresponding to the next expected sequence number is delivered to the higher protocol layer;
• a timer based stall avoidance procedure;
• or
• a window based stall avoidance procedure, the avoidance procedures allowing the receiver window to move forward despite a next expected sequence number not being received from the transmitter,
• wherein the receiver entity is further adapted to;
• derive an accumulated quality parameter pertaining to the packet data being communicated from the transmitter entity to the receiver entity;
• compare, at the control message handler, the accumulated quality parameter with a predetermined threshold value;
• and
• if the control message handler establishes that the accumulated quality parameter meets predefined criteria, moving the receiver window, whereby the highest received value is forwarded to a position corresponding to the received sequence number;
• and setting the next expected value in the receiver window forward to a position corresponding to a rear position of the window determined by the window size.