Design and Realization of Variable Digital Filters for Software-Defined Radio Channelizers Using an Improved Coefficient Decimation Method

Abstract

Abstract-Variable digital filters (VDFs) are used in software defined radio handsets for extraction of individual radio channels corresponding to multiple wireless communication standards. In this paper, we propose a VDF based on the improved coefficient decimation method (ICDM). The proposed VDF provides variable lowpass, highpass, bandpass, bandstop and multi-band frequency responses on-the-fly, using the same set of prototype filter coefficients. We present non-pipelined as well as pipelined implementation architectures for the proposed VDF, along with FPGA implementation results for multiple VDF designs. Analysis of the implementation results shows that the pipelined implementations achieve average reductions of 27.66%, 49.17% and 25.59% in the number of occupied slices, dynamic power and energy consumption respectively, when compared with corresponding non-pipelined implementations. Also, the proposed pipelined implementation architecture provides high operating frequencies that are independent of the prototype filter order across different VDF designs. An average maximum frequency of 157.89 MHz is obtained.Index Terms-Variable digital filter, improved coefficient decimation method, software defined radio. 1549-7747 (c)

New Spectrum Efficient Reconfigurable Filtered-OFDM Based L-Band Digital Aeronautical Communication System

“…The proposed reconfigurable fixed coefficient filter offers variable bandwidth baseband bandpass responses and is based on the coefficient decimation method (CDM) and its extensions [6,27]. To begin with, we discuss CDM using a suitable example.…”

“…However, the transition bandwidth and stop-band attenuation deteriorate by factor D. One way to overcome this deterioration is to over-design the prototype filter with higher order. An extension of CDM referred to as modified CDM (MCDM) [6], offers decimated bandpass response with large bandwidth using a smaller value of D than that required in the CDM. In MCDM, all coefficients except every D th coefficient of the prototype filter, F (e jωc ) are discarded followed by sign reversal of every alternate retained coefficient.…”

A power and time efficient radio architecture for LDACS1 air-to-ground communication

“…Numerous works have explored the use of low complexity variable digital filters and filter banks in software defined radio platforms [16], [17], [18] for both spectrum sensing and channelisation. The usage of filter banks for spectrum sensing was proposed in [16].…”

“…The usage of filter banks for spectrum sensing was proposed in [16]. We have recently proposed a low complexity variable digital filter [18] and a filter bank [17] which can be used for multi-standard channelization in software defined radios. Use of such filters and filter banks offers the ability to realize low power reconfigurable radio architectures which can be efficiently implemented using FPGAs.…”

Variable cutoff frequency FIR filters: a survey

“…The combination of CDM and MCDM is termed as improved coefficient decimation method (ICDM), which consists of four distinct coefficient decimation operations -CDM-I, CDM-II, MCDM-I and MCDM-II. These operations are classified as ICDM-I (includes CDM-I and MCDM-I) and ICDM-II (includes CDM-II and MCDM-II)[18]. It can be noted that center frequency resolution of 1/D can be achieved for the subbands in the output frequency responses obtained after performing ICDM-I operations.…”