V.44 Definition

V.44 is a data compression standard for modems that provides substantially greater data speeds than those obtainable with V.42bis, formerly the most widely used modem compression protocol.

Higher compression ratios mean that more data can be transferred in the same amount of time. V.44 provides a particularly noticeable improvement when browsing the web, because HTML files are highly compressible. For most users, data throughput is increased by 20 to 60 percent as compared with V.42bis.

The compression algorithm used in V.44 was developed by Hughes Network System, the world's leading provider of broadband satellite services, for use in such services. It is ideal for packet switched networks, such as the Internet, and late in 1999, the company offered it as an alternative to V.42bis. After a period of review, it was adopted by the international communication standards bodies as a new compression standard called V.44.

Despite this improvement, the algorithm used in V.44 still has a compression ratio substantially lower than those of the algorithms used by popular file compression programs such as WinZip and bzip2. This is because such programs run directly on personal computers, where they have direct access to powerful processors and much memory, thereby allowing the near-simultaneous examination of very large chunks of data (i.e., the entire file), rather than just small pieces of the data as it streams past. Their algorithms are essentially batch processes and perform two-pass compression, which is not performed in real time with the strict latency requirement that is necessary for efficient communications.

Created November 10, 2005.
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