Wavelets and subband coding
Wireless Communications: Principles and Practice
Wireless Communications: Principles and Practice
OFDM for Wireless Multimedia Communications
OFDM for Wireless Multimedia Communications
Wavelet packet division multiplexing and wavelet packet designunder timing error effects
IEEE Transactions on Signal Processing
OWSS: a new signaling system for 100-150-Mb/s wireless LANs
IEEE Wireless Communications
Subspace-based blind channel estimation for OFDM by exploiting virtual carriers
IEEE Transactions on Wireless Communications
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Orthogonal wavelet spread spectrum (OWSS) is a new wireless LAN signaling scheme aimed at bit rates of 100 Mbps or higher. Starting with power complementary full-tree wavelet pulses, it spreads them using a suitable set of PN codes. The resulting system pulses preserve the power complementary property and satisfy the generalized Nyquist criterion, while possessing both a wide time and a wide frequency support. Benefits from these properties include successful equalization in spite of deep local fades caused by multipath channels, and high spectral efficiency-30-40% higher than OFDM for comparable net bit rates. This paper presents an overview of OWSS and explores the fundamental limits to its performance. In the overview, it discusses the properties of the OWSS pulses, the transmit signal spectrum, and the structure of the transmitter/receiver. Then, the investigation of fundamental limits to the performance is carried out by formulating the system as a multi-rate signal processing system, using hierarchical matrices, and thereupon minimizing the total mean-square error (TMSE). The TMSE governs the BER performance of the system, and is defined as the sum of the MSE of the unequalized residual error and the MSE due to the channel noise amplified by the forward equalizer. We formulate the problem at the chip level so as to truly discern the fundamental limits to the performance of the equalizer. This approach enables estimation of the optimum equalizer for mitigating the effect of the multipath channel, prior to correlation and detection blocks embedded in the FE-DFE loop, and thereby the system performance. Simulation results demonstrate its effectiveness. For a 108 Mbps system with a 50 ns delayspread channel, a low BER of 10^-^5 and spectral efficiency up to 5.2 bits/s/Hz can be achieved at an Eb/No of 19 dB.