| Number | Name | Date | Kind |
|---|---|---|---|
| 4831647 | D'Avello et al. | May 1989 | |
| 4891836 | Takahashi | Jan 1990 | |
| 5148472 | Freese et al. | Sep 1992 | |
| 5208847 | Allen | May 1993 |
| Number | Date | Country |
|---|---|---|
| 63-14563 | Jan 1988 | JPX |
| Entry |
|---|
| "CT2 Common Air Interface", Version 1.1, published Jun. 30, 1991 by the European Telecommunications Standards Institute. |