Constellation Rearrangement: Enhancement for Multilevel Modulation Formats and Transmit Diversity

Trans-Modulation in Wireless Relay Networks

“…The aim is to minimize the destination bit error rate (BER). In [5], the idea of constellation rearrangement was implemented by using different constellation arrangements for the transmissions over different diversity branches. The authors considered the case of 16-QAM constellation and showed that constellation rearrangement can significantly improve the destination block error rate performance.…”

Enabling fast OFDM-based wireless networks with combined transmit diversity and multi-level modulation

“…In this paper we also derive a bound for the symbol error probability of the proposed scheme. The obtained reults show that this proposed scheme is outperforming other ARQ schemes presented for OFDM [7], [9], [10].…”

“…In [12], Gidlund presented a combined orthogonal transmitter diversity ·and· multi-level modulation scheme which viewed the signal constellations of the modulation scheme in an augmented signal space formed by the modulation signal dimension and the number of branches of the transmitter diversity scheme as one entity. That scheme can also be viewed as an CoRe scheme and outperformed the one presented in [9].…”

“…It is well known that multilevel modulation formats such as QAM are less power efficient than single level modulation schemes due to reliability variations of the bits mapped onto the modulation symbols. In [9], [10],Wengerter et ale presented a constellation rearrangement (CoRe) scheme which is adopted in the high speed downlink packet access (HSDPA) transmission mode of the universal mobile telecommunications system (UMTS). CoRe consists in swapping the positions andlor negation of the least significant bits (LSB) and aims at "equalizing" the protection degree experienced by the bits 70 Abstract-In this paper, we present some simple techniques for enhancing the diversity provided by retransmissions in OFDM modulations.…”

Performance of Combined Constellation Rearrangement and Space-Time Block Coding Scheme for Multi-Level Modulation

“…Constellation rearrangement or vary the bit-to-symbol mapping between each packet retransmission has shown to be an effective method to exploiting diversity [7], [8]. In [10], [11], Wengerter et al proposed a constellation approach for QAM constellations, where the optimization is based on the log-likelihood ratio (LLR) and adapting among a set of Gray mappings for retransmissions. That approach provides a suboptimal solution.…”