Header compression with a code book

Patent metadata

Field	Value
Publication number	US-9294589-B2
Application number	US-201114127744-A
Country	US
Kind code	B2
Filing date	Jun 22, 2011
Priority date	Jun 22, 2011
Publication date	Mar 22, 2016
Grant date	Mar 22, 2016

Abstract

A method of transmitting data packets is disclosed. The method comprises acquiring a data packet to be transmitted; parsing the data packet to extract at least a part of its header; matching the extracted part of the header with header items stored in a code book database; preparing, if the extracted part of the header matches a header item stored in the code book database, an adapted data packet comprising a code from the code book corresponding to the match replacing the at least part of the header, and the rest of the data packet; and transmitting the adapted data packet, if the adapted data packet is prepared, or the data packet, if no adapted data packet is prepared. A corresponding method of receiving data packets is also disclosed. The method comprises receiving a data transmission; determining whether the data transmission comprises a compressed header indicator for a data packet with a compressed header; and if the data packet is determined to comprise a compressed header, performing the steps of: parsing the data packet to extract a code; looking up a code book database using the extracted code to find corresponding header data; and decompressing the data packet by replacing the compressed header indicator and the extracted code by the header data. A transmitter, receiver, communication system, and computer program for implementing the methods are also disclosed.

First claim

The invention claimed is:

1. A method of transmitting data packets comprising:
acquiring a data packet to be transmitted;
parsing the data packet to extract at least a part of its header;
matching the extracted part of the header with header items stored in a code book database; and
transmitting, if the extracted part of the header does not match a header item stored in the code book database, the data packet without adaption, or
preparing, if the extracted part of the header matches a header item stored in the code book database, an adapted data packet comprising a code from the code book corresponding to the match replacing the at least part of the header, and the rest of the data packet, and transmitting the adapted data packet, wherein
the method further comprises performing the following steps if the extracted part of the header does not match a header item stored in the code book database:
assigning a new header item in the code book comprising a code and the header;
preparing a code book packet comprising the assigned code and the extracted part of the header; and
transmitting the code book packet.

2. The method according to claim 1 , further comprising performing, if the extracted part of the header does not match a header item stored in the code book database, wherein the code book database is representing the header items with hash values of the part of the corresponding header, the steps of:
calculating a hash value for the extracted part of the header;
determining whether a collision between the calculated hash value and any of the stored hash values of the code book database occurs by matching the calculated hash value to the stored hash values; and
performing, if no collision is determined, the steps of:
assigning a new header item in the code book comprising a code and calculated hash value of the header;
preparing a code book packet comprising the assigned code and the extracted part of the header; and
transmitting the code book packet.

3. The method according to claim 2 , wherein the stored hash values further are assigned with an index, wherein if the calculated hash value matches a stored hash value, it is determined whether a further index is free for that hash value, wherein
if no further index if free for that hash value, a collision is determined, and
if a further index is free for that hash value, no collision is determined and the assigning of a new header item assigns the free index to the calculated hash value.

4. The method according to claim 1 , further comprising:
receiving an acknowledgement signal for a previously sent code book packet;
determining whether the acknowledgement signal indicates an ACKnowledgement or a Negative AcKnowledgement; and
storing the assigned new header item in the code book database only if an ACKnowledgement is indicated.

5. The method according to claim 1 , further comprising:
deleting a header item of the code book database if the header item has not been accessed for the preparing of an adapted data packet for a predetermined time, wherein the time is preferably measured in absolute time or number of packet transmissions.

6. The method according to claim 5 , further comprising, upon deleting a header item, transmitting a code book packet comprising a deletion notice for the header item.

7. The method according to claim 1 , wherein the at least part of the header is defined by invariant fields statistically determined to be occurring in a multitude of packets.

8. The method according to claim 7 , wherein the data packet is an Ethernet packet or of type IEEE802.3 and derivations thereof, and the invariant fields comprise Ethernet MAC destination address, Ethernet MAC source address, Ethernet type, zero or multiple additional VLAN customer tag, zero or one additional VLAN service tag, and zero or multiple additional MPLS tags.

9. The method of claim 1 , further comprising:
receiving a data transmission;
determining whether the data transmission comprises a compressed header indicator for a data packet with a compressed header by parsing the data transmission; and
if the data packet is determined to comprise a compressed header, performing the steps of:
parsing the data packet to extract a code;
looking up a code book database using the extracted code to find corresponding header data; and
decompressing the data packet by replacing the compressed header indicator and the extracted code by the header data, or
if no indicator is found, outputting the data packet without decompression processing.

10. A computer program for a transmitter for transmitting data packets, the computer program comprising instructions, which when executed by a processor of the transmitter, causing the transmitter to perform the method according to claim 1 .

11. A method of receiving data packets comprising:
receiving a data transmission;
determining whether the data transmission comprises a compressed header indicator for a data packet with a compressed header by parsing the data transmission; and
if the data packet is determined to comprise a compressed header, performing the steps of:
parsing the data packet to extract a code;
looking up a code book database using the extracted code to find corresponding header data; and
decompressing the data packet by replacing the compressed header indicator and the extracted code by the header data, or
if no indicator is found, outputting the data packet without decompression processing, wherein
the method further comprises performing the following steps if the data transmission is determined not to comprise a compressed header indicator:
determining whether the data transmission corn irises a code book packet; and
if the data transmission comprises a code book packet, performing the steps of:
extracting a code part and a header part from the code book packets; and
storing in the code book database a header item in the code book database using the extracted code part and the header part.

12. The method according to claim 11 , further comprising transmitting an acknowledgement signal for a received code book packet, the acknowledgement signal indicates an ACKnowledgement or a Negative AcKnowledgement, wherein the AcKnowledgement indicates successful storing of the new header item in the code book database.

13. The method according to claim 11 , further comprising, upon receiving a code book packet comprising a deletion notice for a header item, deleting the header item of the code book database corresponding to the header item.

14. A computer program for a receiver for receiving data packets, the computer program comprising instructions, which when executed by a processor of the receiver, causing the receiver to perform the method according to claim 11 .

15. A transmitter arranged for transmitting data packets comprising:
a data input arranged to acquire a data packet to be transmitted;
a parser arranged to parse the data packet to extract at least a part of its header;
a code book database enabling storing of header items by association to codes, respectively, under control of a code book handler;
a search mechanism arranged to match the extracted part of the header with header items stored in the code book database;
a compressing mechanism arranged to, if the extracted part of the header matches a header item stored in the code book database, prepare an adapted data packet comprising a code from the code book corresponding to the match replacing the at least part of the header, and the rest of the data packet; and
a radio transmitter arranged to transmit the adapted data packet, if

Assignees

• Crosta Simone
• Angelini Andrea
• Clima Laura
• Grenabo Hakan
• Vincenzi Massimo
• Ericsson Telefon Ab L M

Inventors

• Crosta Simone
• Angelini Andrea
• Clima Laura
• Grenabo Hakan
• Vincenzi Massimo

Classifications

• H04L45/7453

  using hashing · CPC title

• H04L69/04 Primary

  Protocols for data compression, e.g. ROHC · CPC title

• H04W28/06

  Optimizing {the usage of the radio link}, e.g. header compression, information sizing {, discarding information (system modifying transmission characteristic according to link quality by modifying frame length H04L1/0007; dynamic adaptation of the packet size for flow control or congestion control H04L47/365)} · CPC title

• H04L69/22

  Parsing or analysis of headers · CPC title