Time-Frequency Channel Parameterization with Application to Multi-Mode Receivers

Abstract

There is a trend towards flexible radios which are able to cope with a range of wireless communication standards. For the integrated processing of widely different signals-including single-carrier, multicarrier, and spread-spectrum signals-monolithic baseband receivers need universal formats for the signal representation and channel description. We consider a reconfigurable receiver architecture building on concepts from time-frequency (TF) signal analysis. The core elements are TF signal representations in form of a Gabor expansion along with a compatible parameterization of time-variant channels. While applicable to arbitrary signal types, the TF channel parameterization offers similar advantages as the frequency domain channel description employed by orthogonal frequencydivision multiplexing receivers. The freedom in the choice of the underlying analysis window function and the scalability in time and frequency facilitate the handling of diverse signal types as well as the adaptation to radio channels with different delay and Doppler spreads. Optimized window shapes limit the inherent model error, as demonstrated using the example of direct-sequence spread-spectrum signaling.

Implementation Aspects in DFT Modulated Filter Bank Transceivers for Cognitive Radio

“…The approach is currently extended to the case of time-/frequency selective fading channels [16] where the channel parameterization translates into properties of the corresponding TF signal representations, and the resulting pulses will be applied to indoor cognitive radio environments. FC and g as a function of ξ = γ and δ = 3dB.…”

Dual mode spectroscopic biomedical sensor: Technical considerations for the wireless testbed*

“…As follows from [35,36], we have to find a prototype function g[n] that minimizes the mean square error per TF coefficient in dispersive channels. Mathematically,…”

“…From the research work in wireless systems, this simple approximation is only optimum for non-dispersive channels [35][36][37]. Orthogonality of Gabor atoms will be seriously distorted by dispersive channel.…”