Backward looking robust header compression receiver

摘要

Robust Header Compression (ROHC) offers a way to compress packet header information for more efficient transmission of data. The compression is achieved through various confidence modes set up by the transmitter and the receiver. The Initialization and Refresh state (IR) is the first state of the compressor. This provides a complete, uncompressed context of the data that is being transmitted. In typically operation, the ROHC compressor will periodically transmit IR packets providing context information allowing the ROHC decompressor to decompress one or more packets following the IR packet. However, under certain conditions such as decompressor start-up, it is possible for the decompressor to miss an IR packet. Exemplary methods and apparatus are described in which a decompressor uses a later-received IR packet to decompress earlier packets for which the decompressor had not received context information.

主权项

1. A backward looking apparatus for decompressing compressed data packets comprising:
a receiver for receiving a first compressed data packet transmitted in a first time slice and an initialization packet after the first compressed data packet, wherein the initialization packet contains context information and is first transmitted in a second time slice following the first time slice and contains context information pertaining to the second time slice; a processor for re-creating context information for decompressing the first compressed data packet from the context information contained in the initialization packet, wherein the processor derives context information from the context information contained in the initialization packet; and the processor decompressing the first compressed data packet using the re-created context information, wherein the receiver receives a second compressed data packet after the initialization packet, and the processor decompresses the second compressed data packet using the context information contained in the initialization packet.