Summary: An Optimized CostEffective Multicarrier Transceiver for TwoRay Channels
Naofal AlDhahir \Lambda , Member IEEE
Information Systems Laboratory
Stanford University, Stanford CA 94305
EDICS Category 2:8 (DSP Applications)
The optimum set of modulation filters for multicarrier modulation on two--ray channels is derived in
closed--form. These filters are shown to be sinusoidal even for a finite number of carriers.
The proposed modulation scheme optimizes the performance of two--ray channels corrupted by addi
tive white Gaussian noise without incurring the data rate loss associated with FFT--based multicarrier
transceivers. The case of multiple--ray channels is also considered.
Multicarrier modulation (MCM) has attracted considerable attention recently as a viable transmission tech
nology on spectrally--shaped channels [7, 3]. It involves the use of an orthogonal set of modulation basis
vectors at the transmitter to partition the channel response into a large number of parallel, independent, and
memoryless subchannels that can be individually decoded.
The optimum modulation basis vectors require the computation of the complete eigen--decomposition of
a channel--dependent matrix, which becomes a formidable task even for a moderate number of subchannels
. In a suboptimum but computationally--efficient implementation of MCM known as the discrete multitone
transceiver (DMT), a cyclic prefix is added to each input block to make the the channel matrix circulant, and