EXPURGATED PULSE POSITION MODULATION FOR COMMUNICATION

摘要

An expurgated pulse position modulation (EPPM) technique can be used to encode information for wireless transmission. Such an EPPM technique can be compatible with a simple receiver architecture, such as including a shift register and pulse position modulation (PPM) decoder. A multi-level EPPM (MEPPM) approach can increase the available symbols in the modulation constellation and can be used to accommodate multiple users or devices concurrently. Interleaving techniques can be used such as to reduce inter-symbol interference. An optical transmitter and an optical receiver can be used, such as including using energy in a visible range of frequencies. In an example, an optical source such as including one or more light emitting diodes can provide visible light for illumination, and the EPPM technique can include using codewords specified to provide a desired dimming level when such codewords are used to intensity modulate the optical source, without perceptible flicker.

主权项

1. A system comprising:
a digital modulator circuit configured to provide digitally encoded information using a pulse-position modulation (PPM) encoding scheme, the pulse-position modulation encoding scheme including modulated information comprising a linear combination of expurgated PPM (EPPM) symbols, the EPPM symbols selected from a constellation including (1) a cyclic series of symbols or (2) a combination of the cyclic series of symbols and logical complements of the cyclic series of symbols; and a wireless transmitter configured to receive information from the digital modulator circuit and configured to wirelessly transmit the modulated information by varying an amplitude of an output signal.