A Generalized Prefix Construction for OFDM Systems Over Quasi-Static Channels

Abstract

All practical OFDM systems require a prefix to eliminate inter-symbol interference at the receiver. Cyclic prefix (CP) and zero-padding are well-known prefix construction methods, the former being the most employed technique in practice due to its lower complexity. In this paper we construct an OFDM system with a generalized CP. It is shown that the proposed generalized prefix effectively makes the channel experienced by the packet different from the actual channel. Using an optimization procedure, lower bit error rates can be achieved, outperforming other prefix construction techniques. At the same time the complexity of the technique is comparable to the CP method. The presented simulation results show that the proposed technique not only outperforms the CP method, but is also more robust in the presence of channel estimation errors and mobility. The proposed method is appropriate for practical OFDM systems.

High-performance MIMO OFDM wireless systems with generalized prefix

“…Genelleştirilmişönek'in SISO durumunda daha iyi bir performans gösterdigi [10]'da gösterilmiştir.İyileştirme derin sönümlü veya izgesel sıfıra sahip kanallar için daha da büyüktür.…”

“…Bu makalenin amacı, [10]'daki yaklaşımın MIMO durumunda da uygulanabilir oldugunu göstermektir. Genelleme kaybı olmadan iki verici iki alıcı antenli bir sistem gözönünde bulundurulmuştur.…”

“…Genelleştirilmişönek için ψ'in optimum degeri, bir tek boyutlu iyileştirme prosedürü ile seçilir. Tüm taşıyıcılar kullanıldıgında, [10]'da gösterildigi gibi, bit hata oranı tek şekilli bir fonksiyonudur. Ancak, kullanılmayan taşıyıcılar oldugunda, bit hata oranı, iyileştirme prosedürü tarafından dikkate alınması gereken tek şekilli bir fonksiyon degildir.…”

Generalised prefix for space–time block‐coded orthogonal frequency division multiplexing wireless systems over correlated multiple‐input multiple‐output channels

“…Recently, another prefix construction technique called generalised prefix (GP) was proposed for OFDM systems [17] that also diagonalises the channel matrix, that is, the CP is not the only prefix with this property. It was also shown that this GP-OFDM system has the lowest BER among the other prefix construction techniques, considering all other parameters identical.…”

“…The paper is organised as follows: In Section 2, we discuss the OFDM system model to introduce the notations. The signal model in [17] is simplified and written as a vector-matrix form for single-input single-output (SISO) systems, which, in turn, is easier to apply to the MIMO case. In Section 3, we develop STBC-GP-OFDM.…”