Abstract
A design technique is presented to reduce the search time for trellis codes with multilevel/phase modulation. Codes are constructed by connecting trellis diagrams for codes with fewer states in parallel. For example, an N-state code can be constructed by connecting two N/2-state codes. The way in which the embedded codes are connected increases the upper limit on minimum free distance otherwise imposed by parallel transitions between states. In some cases, this technique can reduce the number of codes in a code search by a factor of approximately 2’, the number of coder states. A computer search incorporating this technique for eight-level amplitude modulation (8-AM) codes having 211 and 212 states produced codes with greater minimum free distance than reported previously [1] (i.e., greater than 6 dB coding gain). New eight-level phase shift-keying (8-PSK) codes, which have a different structure from previously reported codes [1], are also presented.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 218-221 |
| Number of pages | 4 |
| Journal | IEEE Transactions on Communications |
| Volume | 36 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1988 |
ASJC Scopus subject areas
- Electrical and Electronic Engineering