A low complexity reconfigurable channel filter based on decimation, interpolation and frequency response masking

Dhabu, Sumedh; Smitha, K. G.; Vinod, A. P.

doi:10.1109/icassp.2013.6638732

Cited by 3 publications

(10 citation statements)

References 8 publications

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“…In these techniques, the bandwidth of the prototype filter is first increased by applying CDM-II operation (factor D) on the prototype filter, and multiband response with narrower bandwidth is then obtained by using interpolation (factor M). In [25], additionally, lowpass-to-highpass transformation is used. This transformation consists of reversing the sign of every alternate coefficient of the filter, whose highpass version is to be obtained.…”

Section: Interpolation -Frequency Response Masking Based Vcf Filtersmentioning

confidence: 99%

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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Section: Interpolation -Frequency Response Masking Based Vcf Filtersmentioning

confidence: 99%

Variable cutoff frequency FIR filters: a survey

et al. 2020

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“…The most common architectures are based on the Cosine Modulated Filter Bank (CMFB), Discrete Fourier Transform Filter Bank (DFTFB) and Per-Channel Filter Bank (PCFB). Aside from these well-established architectures, several other interesting designs for application-specific channelizers can be found in [13,14,9,10].…”

Section: Background and Related Workmentioning

confidence: 99%

“…Then we transform the power measurement relative to the maximum and minimum power that the system consumes in all of the possible states (g 2 ). The result is shown in Equation 8 and Equation 9.…”

Section: Multiobjective Rewardsmentioning

confidence: 99%

Reconfigurable Digital Channelizer Design Using Factored Markov Decision Processes

Sapio

et al. 2017

J Sign Process Syst

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In this work, a novel digital channelizer design is developed through the use of a compact, system-level modeling approach. The model efficiently captures key properties of a digital channelizer system and its time-varying operation. The model applies powerful Markov Decision Process (MDP) techniques in new ways for design optimization of reconfigurable channelization processing. The result is a promising methodology for design and implementation of digital channelizers that adapt dynamically to changing use cases and stochastic environments while optimizing simultaneously for multiple conflicting performance goals. The method is used to employ an MDP to generate a runtime reconfiguration policy for a time-varying environment. Through extensive simulations, the robustness of the adaptation is demonstrated in comparison with the prior state of the art.

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“…The prototype filter and the complementary filter are interpolated by a factor I to get the corresponding multi-band responses Ha(z I ) and Hc(z I ) respectively. From these interpolated frequency responses, the unwanted subbands are masked by cascading suitable low order frequency response masking filters Hma(z) and Hmc(z) as shown in Based on the combination of coefficient decimation, interpolation and FRM techniques, VDFs have been proposed in [55,56] for channelization in SDR receivers.…”

Section: Variable Digital Filters Providing Discrete Control Over Cutmentioning

confidence: 99%

“…The VDF in [56] is an improved version of the VDF in [55] and provides a greater number of distinct frequency responses with an improved center frequency resolution.…”

Section: Variable Digital Filters Providing Discrete Control Over Cutmentioning

confidence: 99%

Design of low complexity variable digital filters and filter banks for software defined radio receivers

Ambede¹

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To seamlessly support the existing and upcoming wireless communication standards, the software defined radio (SDR) has been proposed as a solution. SDRs can process signals of different wireless communication standards by software reconfiguration of the same transceiver architecture, thereby reducing hardware resource utilization and associated costs. To perform multi-standard channelization, i.e., extraction of desired radio channels (frequency bands) from a wideband input signal, SDR receivers typically employ variable digital filters (VDFs) and filter banks that provide variable frequency responses by controlling a small set of parameters. VDFs and filter banks are also used in SDR based cognitive radios (CRs) to perform spectrum sensing (detection of presence/ absence of licensed user signals in a wideband input frequency range) for dynamic spectrum access, to achieve opportunistic and efficient usage of the radio frequency spectrum. Realizing such VDFs and filter banks which showcase the desired attributes of high frequency response flexibility and low implementation complexity is a challenging task. To address this challenge, new algorithms and various architectures for designing VDFs and filter banks have been proposed in this thesis. The first work presents design techniques to obtain variable frequency responses using the same set of prototype filter coefficients, along with the corresponding mathematical formulations. Two techniques are proposeda modified coefficient decimation method (MCDM) and the improved coefficient decimation method (ICDM), the latter being a combination of the proposed MCDM and the conventional coefficient decimation method (CDM). Both the proposed techniques, i.e., MCDM and ICDM, involve selective usage of filter coefficients by performing operations such as replacing them by zeros and retaining/ discarding them appropriately to obtain variable frequency responses. The ICDM is categorized into ICDM-I and ICDM-II, each comprising of two distinct coefficient decimation operations. The ICDM provides discrete control over the bandwidths and center frequencies of the subbands in the obtained frequency responses. iv The second work presents the design of VDFs which can be used for channelization in SDR receivers. Three such VDFs, one each based on ICDM-I, ICDM-II and comprehensive ICDM are proposed and analysed. The comprehensive ICDM based VDF involves both ICDM-I and ICDM-II operations and features their constituent advantages while minimizing the effects of their individual limitations. The comprehensive ICDM based VDF can provide variable lowpass, highpass, bandpass, bandstop and multi-band frequency responses on-the-fly, by performing appropriate ICDM operations on the same set of prototype filter coefficients. Similar to the design of VDFs based on ICDM-I, ICDM-II and comprehensive ICDM, the third work presents design of filter banks based on these three techniques. While the ICDM-I based filter bank can only be used for uniform channelization, the ICDM-II and comprehensive ICDM ...

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A low complexity reconfigurable channel filter based on decimation, interpolation and frequency response masking

Cited by 3 publications

References 8 publications

Variable cutoff frequency FIR filters: a survey

Variable cutoff frequency FIR filters: a survey

Reconfigurable Digital Channelizer Design Using Factored Markov Decision Processes

Design of low complexity variable digital filters and filter banks for software defined radio receivers

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