A Class of Multimode Transmultiplexers Based on the Farrow Structure

Eghbali, Amir; Johansson, Håkan; Lowenborg, P.

doi:10.1007/s00034-011-9351-4

Cited by 13 publications

(19 citation statements)

References 33 publications

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“…The main difference between the approaches in [25][26][27][28][29] lies in the implementation of the SRC blocks C p andĈ p . However, they all utilize the Farrow structure 9 and aim to design the system in such a way that, at any time, any user can transmit/receive data streams with any bandwidth and centered at any point in the frequency spectrum.…”

Section: Approach Ii: Use Of Transmultiplexersmentioning

confidence: 99%

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Dynamic Frequency-Band Reallocation and Allocation: from Satellite-Based Communication Systems to Cognitive Radios

Eghbali

Johansson

Lowenborg

et al. 2009

J Sign Process Syst

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This paper discusses two approaches for the baseband processing part of cognitive radios. These approaches can be used depending on the availability of (i) a composite signal comprising several user signals or, (ii) the individual user signals. The aim is to introduce solutions which can support different bandwidths and center frequencies for a large set of users and at the cost of simple modifications on the same hardware platform. Such structures have previously been used for satellitebased communication systems and the paper aims to outline their possible applications in the context of cognitive radios. For this purpose, dynamic frequencyband allocation (DFBA) and reallocation (DFBR) structures based on multirate building blocks are introduced and their reconfigurability issues with respect to the required reconfigurability measures in cognitive radios are discussed.

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Section: Approach Ii: Use Of Transmultiplexersmentioning

confidence: 99%

“…For this purpose, transmultiplexer-based (TMUX-based) approaches [25][26][27][28][29] capable of generating different user signals with different bandwidths will be discussed. These approaches support systems which dynamically move between different access technologies along the available spectrum pool [5].…”

Section: Contribution Of the Papermentioning

confidence: 99%

Dynamic Frequency-Band Reallocation and Allocation: from Satellite-Based Communication Systems to Cognitive Radios

Eghbali

Johansson

Lowenborg

et al. 2009

J Sign Process Syst

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“…Any of the TMUXs, in the references Eghbali et al (2007a;2008a;2009b;2010); Eghbali, Johansson & Löwenborg (2011a;, can be used here. The TMUX, in Eghbali et al (2010);Eghbali, Johansson & Löwenborg (2011b), has a rather different structure.…”

Section: Structure Of the Tmuxmentioning

confidence: 99%

“…The TMUX, in Eghbali et al (2010);Eghbali, Johansson & Löwenborg (2011b), has a rather different structure. Instead of variable lowpass filters and frequency shifters as, in Eghbali et al (2007a;2008a;2009b); Eghbali, Johansson & Löwenborg (2011a), it performs bandpass rational SRC using flexible commutators and fixed bandpass filters. However, one can generally describe it in terms of Fig.…”

Section: Structure Of the Tmuxmentioning

confidence: 99%

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Reconfigurable Multirate Systems in Cognitive Radios

Eghbali¹,

Johansson²

2012

Foundation of Cognitive Radio Systems

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Variable cutoff frequency FIR filters: a survey

et al. 2020

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Many signal processing applications require digital filters with variable frequency characteristics, especially the filters with variable bandwidth. Due to their linear phase and inherent stability, variable bandwidth finite impulse response (FIR) filters are the popular choice in majority of the applications. Once a variable cutoff frequency (VCF) FIR lowpass filter is designed, variable bandwidth bandpass / highpass / bandstop filters and reconfigurable filter banks can be realized from the same. In this paper, we present a comprehensive review of the existing variable cutoff frequency FIR filter design techniques, including the developments in the recent two decades. We provide the basic concepts, design and architectural details for each of these techniques and the major developments / incremental works thereof. Qualitative as well as quantitative comparisons are provided to assist the reader in choosing the most suitable VCF filter design technique for a particular application. Keywords FIR filters, reconfigurable filters, variable digital filters IntroductionCompared to analog filters, digital filters have advantage of higher accuracy, exact linear-phase (if desired), time-invariant performance (analog filter performance changes due to component drift), relatively smaller silicon area etc. These advantages, coupled with the advent of VLSI technology, have resulted in ubiquitous presence of digital filters in almost all the signal processing applications with a few exceptions (such as wideband filtering in radio frequency range, which is not feasible due to the bottleneck at the speed of analog-to-digital converters).Digital filters with variable frequency response characteristics are required for numerous critical applications in the fields of digital communications, audio signal processing, biomedical signal processing etc. [1,2]. In digital communications domain alone, digital filters with variable frequency response characteristics can be used for spectrum analysis, spectrum shaping, channelization, and receiver synchronization. For e.g., a digital filter having tuneable passband and transition bandwidths is used for channel extraction in a multi-standard wireless communication receiver, as it needs to be interoperable with multiple communication standards having distinct bandwidth specifications. Alternatively, a digital modem uses a digital filter to implement variable fractional delays. In general, a digital filter whose frequency response can be changed on-the-fly is called a variable digital filter. Even though such a definition means that all the parameters related to the frequency response should be variable, in practice, majority of the applications demand only a lowpass filter with variable cutoff frequency (fc), satisfying the desired minimum specifications of transition bandwidth (tbw), passband ripple (δp) and stopband ripple (δs). Therefore, the VCF (variable cutoff frequency) filter design task can be simplified further, by specifying the maximum limit on tbw, δp, and δs, and thus, only one...

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A Class of Multimode Transmultiplexers Based on the Farrow Structure

Cited by 13 publications

References 33 publications

Dynamic Frequency-Band Reallocation and Allocation: from Satellite-Based Communication Systems to Cognitive Radios

Dynamic Frequency-Band Reallocation and Allocation: from Satellite-Based Communication Systems to Cognitive Radios

Reconfigurable Multirate Systems in Cognitive Radios

Variable cutoff frequency FIR filters: a survey

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