Combined Transmitter Diversity and Multi-Level Modulation Techniques

Abstract

Abstract:Orthogonal transmitter diversity such as frequency diversity and time diversity is quite simple to implement and, with optimum signal combining, can take full advantage of fading multipath channels. However, such a scheme has a bandwidth efficiency that decreases inversely with the number of diversity branches making it less attractive in wireless communications applications. This paper considers combined orthogonal transmitter diversity and multi-level linear modulation techniques. The idea is to view 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. This augmented signal space provides a good spread for the modulation signal points and can be quite efficient for high-level linear modulation techniques. The obtained results show that this combined scheme, not only improves the system performance in both additive white Gaussian noise and fading multipath channels, but also improves the bandwidth efficiency of orthogonal transmitter diversity.

Constellation constrained multiuser multiple‐input multiple‐output for high capacity and error performance over correlated fading channels

“…In [24], different scenarios have been presented for signal design of two users equipped with a single antenna by applying constellation rearrangement to increase the minimum distance of composite received signals. The idea of constellation design has been adopted in many studies to improve the performance of wireless systems [25][26][27][28][29][30][31]. For example, rotation of transmitted signal constellations is employed in [25][26][27] to enlarge the capacity region of different orthogonal and non-orthogonal two-user Gaussian multiple access and broadcast channels.…”

“…It is utilized also in to construct space‐time block code (STBC) pairs for two‐user MISO and two‐user MIMO systems over fading channel. In , rearrangement of the constellation points is investigated to improve the system performance and bandwidth efficiency of transmit diversity in both Gaussian and fading channels. In , optimized signal constellation is proposed with network coding for two‐way wireless relaying applications.…”

Constellation rearrangement for 4-PAM repetition coding

“…Sinyal kümesi sekillendirmesi ilk olarak [2]'de hibrit otomatik tekrar istegi (hybrid automatic repeat request, HARQ) için uygulanmıştır. [3] ve [4]'te verici çeşitlemesi uygulanan sistemlerde, bu teknik ile her çeşitleme kolunda farklı sinyal eşleştirmesi kullanarak alıcıda bit güvenilirliklerinin iyileştirilebildigi gösterilmiştir. Otomatik tekrar istegi kullanılan sistemler için her tekrarda alınacak sinyal kümesişekillendirmesi [5]'te çalışılmıştır.…”