| 摘要 |
There is disclosed a method of transmitting data packets from a transmitter to a receiver each having a stack of communication protocol layers which comprises a data Link Layer (LL), by using a Segmentation And Re-assembly (SAR) mechanism implemented within a SAR layer intermediate between the LL and an upper layer, as well as an error recovery mechanism implemented within the LL. The SAR mechanism performs, in a transmission direction, the function of segmenting Parent Packets (PPs) handled by the upper layer into consecutive segments of shorter length and the function of providing some segmentation information. The segmentation information comprises, for each segment, a two-level sequence numbering comprising a PP Sequence Number (PPSN) which identifies the PP which said segment belongs to, and a Segment Sequence Number (SSN) which identifies the rank of the segment within the PP. The error recovery mechanism implements a selective retransmission scheme using forward and/or feedback signaling messages which embed the two-level segment numbering. In the receive direction, the SAR mechanism delivers to the upper layer a PP of given PPSN of which all constitutive segments are correctly received and re-assembled, irrespective of whether all PPs of sequence number lower than that PPSN are already delivered.
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