Combination of block-coded modulation and trellis-coded modulation

It is known that trellis-coded modulation (TCM) can give a significant coding gain without compromising bandwidth efficiency, by the concepts of signal set partition and trellis coding scheme. It is also known that block-coded modulation (BCM) can be used to approach closely the maximum energy saving that can be obtained by using the densest lattice over the rectangular lattice (QAM). In this paper a systematic scheme is proposed to combine TCM and BCM, such that the constructed coded modulation is similar to part of Wei´s multidimensional TCM (1987). The main idea is that the signal points that are used in multidimensional TCM should be partitioned according to the dense lattices formed by proper BCM. Hence a higher coding gain is obtained which is a combination of both the distance gain of TCM and the density gain of BCM. In the 2n-dimensional case, for n>or=4, the net asymptotic coding gain of this scheme can theoretically reach (6-3/n) dB.<>