| 摘要 |
A new air interface protocol compliant with narrowband (12.5 kHz) channels being mandated for use in North America provides a narrowband (i.e., 18 kbps-19.2 kbps), two-slot scaled version of the European TETRA time division signaling that can accommodate different vocoder frame formats. Any vocoder having a frame size that is a submultiple of a certain frame rate can be used. The new air interface is fully compatible with prior frequency division signaling control channels. Adaptive vocoder selection can allow a radio to dynamically select between different vocoding standards and indicate its selection through over-the-air signaling.
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