Compression techniques for mobile data terminal communication

The author introduces a technique for compressing mobile data terminal messages to improve system capacity. Messages are divided into two types based on their content. One type, which contains messages composed of English text, is compressed to an average of 3.25 bits/character using a static dictionary technique. The other type, which contains messages which are partially English text and partially nonEnglish alphanumeric data, is compressed to an average of 5.03 bits/character via single-character Huffman encoding. For public safety applications, this two-type compression method yields a 69% improvement in system capacity relative to standard 7 bits/character ASCII encoding