Multicarrier modulation with low PAR: applications to DSL and wireless
Multicarrier modulation with low PAR: applications to DSL and wireless
OFDM for Wireless Multimedia Communications
OFDM for Wireless Multimedia Communications
On Limits of Wireless Communications in a Fading Environment when UsingMultiple Antennas
Wireless Personal Communications: An International Journal
Convex Optimization
Optimal training design for MIMO OFDM systems in mobile wireless channels
IEEE Transactions on Signal Processing
IEEE Transactions on Signal Processing
Estimation of continuous flat fading MIMO channels
IEEE Transactions on Wireless Communications
Optimal training for MIMO frequency-selective fading channels
IEEE Transactions on Wireless Communications
IEEE Transactions on Wireless Communications
Space-time block codes from orthogonal designs
IEEE Transactions on Information Theory
Frequency domain equalization for single-carrier broadband wireless systems
IEEE Communications Magazine
A simple transmit diversity technique for wireless communications
IEEE Journal on Selected Areas in Communications
Channel estimation for OFDM systems with transmitter diversity in mobile wireless channels
IEEE Journal on Selected Areas in Communications
Capacity limits of MIMO channels
IEEE Journal on Selected Areas in Communications
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Multiple-input multiple-output (MIMO) systems have shown a huge potential for increased spectral efficiency and throughput. With an increasing number of transmitting antennas comes the burden of providing training for channel estimation for coherent detection. In some special cases optimal, in the sense of mean-squared error (MSE), training sequences have been designed. However, in many practical systems it is not feasible to analytically find optimal solutions and numerical techniques must be used. In this paper, two systems (unique word (UW) single carrier and OFDM with nulled subcarriers) are considered and a method of designing near-optimal training sequences using nonlinear optimization techniques is proposed. In particular, interior-point (IP) algorithms such as the barrier method are discussed. Although the two systems seem unrelated, the cost function, which is the MSE of the channel estimate, is shown to be effectively the same for each scenario. Also, additional constraints, such as peak-to-average power ratio (PAPR), are considered and shown to be easily included in the optimization process. Numerical examples illustrate the effectiveness of the designed training sequences, both in terms of MSE and bit-error rate (BER).