Space-time codes for linearly labelled PAM, PSK, QAM and related constellations using gray mapping
Gray-labeling of signal constellations is common practice in wireless communications systems because Gray-labeling minimizes bit error rates at high signal–to-noise ratios for most channels. In systems employing transmit diversity schemes based on space-time block codes, Lu-Kumar construction provides codes that are optimal in terms of rate-diversity tradeoff. Lu-Kumar codes, however, are not directly compatible with Gray-mapped constellation labels.
By introducing novel transformations into Lu-Kumar space-time code constructions for 2k–PAM, 2k–PSK, and 4k–QAM constellations, APL researchers have developed new constructions for codes that retain the Lu-Kumar optimal rate-versus-diversity properties, yet are suitable for many different constellation labelings, including Gray–mapped constellation labels. This advancement in space-time code construction enables 2k–PAM, 2k–PSK, and 4k–QAM constellations to achieve the maximum transmission rate possible for a given signaling constellation and achieved transmit diversity level.
Patent Status: U.S. patent(s) 7675990 issued.CONTACT:
Mr. M. T. Hickman