Citation
Abstract
In optical communication systems employing direct detection at the receiver, intensity modulations such as on–off keying (OOK) or pulse-position modulation (PPM) are commonly used to convey the information. Consider the possibility of applying space-time coding in such a scenario, using, for example, an Alamouti-type coding scheme [1]. Implicit in the Alamouti code is the fact that the modulation that defines the signal set is such that it is meaningful to transmit and detect both the signal and its negative. While modulations such as phase-shift keying (PSK) and quadrature amplitude modulation (QAM) naturally fall into this class, OOK and PPM do not since the signal polarity (phase) would not be detected at the receiver. We investigate a modification of the Alamouti code to be used with such modulations that has the same desirable properties as the conventional Alamouti code but does not rely on the necessity of transmitting the negative of a signal.
Keywords
Details
- Volume
- 42-155
- Published
- November 15, 2003
- Pages
- 1–9
- File Size
- 118.9 KB