TY - JOUR
T1 - MMSE turbo equalisation for real-valued symbols
AU - Dietl, Guido
AU - Utschick, Wolfgang
PY - 2006/5
Y1 - 2006/5
N2 - This paper deals with iterative or turbo receivers where the maximum a posteriori detector has been replaced by a widely linear filter minimising the mean square error, that is the widely linear Wiener Filter (WF). In communication systems where the transmitted symbols can be assumed to be realisations of a non-circular random variable, widely linear processing outperforms the linear one. Besides the non-circularity due to the a priori information fed back in the turbo scheme, we investigate real-valued modulation alphabets which are non-circular even if the a priori information is zero. We derive the widely linear WF for this case and observe that the number of floating point operations involved in its computation, is higher than the one of the linear WF. Nevertheless, they have the same order of computational complexity. Moreover, we reveal the relationship between the proposed widely linear equaliser and interference cancellation based on the available a priori information. Simulation results of a frequency-selective turbo system show that despite of the increased computational complexity, the performance gain of widely linear processing compared to the linear one, is negligible. However, in systems without turbo feedback, the widely linear WF outperforms tremendously the linear one.
AB - This paper deals with iterative or turbo receivers where the maximum a posteriori detector has been replaced by a widely linear filter minimising the mean square error, that is the widely linear Wiener Filter (WF). In communication systems where the transmitted symbols can be assumed to be realisations of a non-circular random variable, widely linear processing outperforms the linear one. Besides the non-circularity due to the a priori information fed back in the turbo scheme, we investigate real-valued modulation alphabets which are non-circular even if the a priori information is zero. We derive the widely linear WF for this case and observe that the number of floating point operations involved in its computation, is higher than the one of the linear WF. Nevertheless, they have the same order of computational complexity. Moreover, we reveal the relationship between the proposed widely linear equaliser and interference cancellation based on the available a priori information. Simulation results of a frequency-selective turbo system show that despite of the increased computational complexity, the performance gain of widely linear processing compared to the linear one, is negligible. However, in systems without turbo feedback, the widely linear WF outperforms tremendously the linear one.
UR - http://www.scopus.com/inward/record.url?scp=33745796559&partnerID=8YFLogxK
U2 - 10.1002/ett.1126
DO - 10.1002/ett.1126
M3 - Article
AN - SCOPUS:33745796559
SN - 1124-318X
VL - 17
SP - 351
EP - 359
JO - European Transactions on Telecommunications
JF - European Transactions on Telecommunications
IS - 3
ER -