This paper discusses the design of a filter bank based transceiver capable of simultaneously up- or downconverting the entire TV white space (TVWS) frequency band. The spectral mask requirements favour a filter bank based approach, whereby RF sampling and the use of an FPGA for digital up- and down-conversion dictates a two-stage approach. Some of the design considerations, including filter design approaches, are discussed in this contribution

Crockett, Louise Helen

Darbari, Faisal

Elliot, Ross Andrew

Enderwitz, Martin

Stewart, Robert

Weiss, Stephan

English

Name not available

Design considerations for a filter bank based TVWS transceiver

University of Strathclyde Institutional Repository

Strathprints Institutional RepositoryElliot, Ross Andrew and Enderwitz, Martin and Darbari, Faisal and Crockett, Louise Helen andWeiss, Stephan and Stewart, Robert (2012) Design considerations for a filter bank based TVWStransceiver. In: URSI UK Festival of Radio Science, 2012-04-19 - 2012-04-19, Durham.Strathprints is designed to allow users to access the research output of the University of Strathclyde.Copyright c© and Moral Rights for the papers on this site are retained by the individual authorsand/or other copyright owners. You may not engage in further distribution of the material for anyprofitmaking activities or any commercial gain. You may freely distribute both the url (http://strathprints.strath.ac.uk/) and the content of this paper for research or study, educational, ornot-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to Strathprints administrator:mailto:strathprints@strath.ac.ukhttp://strathprints.strath.ac.uk/DESIGN CONSIDERATIONS FOR A FILTER BANK BASED TVWS TRANSCEIVERR.A. Elliot, M.A. Enderwitz, F. Darbari, L.H. Crockett, S. Weiss and R.W. StewartCentre for White Space CommunicationsDepartment of Electronic & Electrical Engineering, University of Strathclyde, Glasgow, Scotland, UK{ross.elliot,martin.enderwitz,faisal,louise,stephan,bob}@eee.strath.ac.ukAbstract. This paper discusses the design of a filter bankbased transceiver capable of simultaneously up- or downcon-verting the entire TV white space (TVWS) frequency band.The spectral mask requirements favour a filter bank basedapproach, whereby RF sampling and the use of an FPGAfor digital up- and down-conversion dictates a two-stage ap-proach. Some of the design considerations, including filterdesign approaches, are discussed in this contribution.Introduction. TVWS radio devices need to operate flexiblyin order to be able to utilise geographically unused TV chan-nels. At the same time, these radio devices are expected tocomply with very stringent requirements of -55dB leakageinto adjacent channels and -69dB leakage into next-adjacentfrequency bands [1]. Orthogonal frequency division multi-plexing (OFDM) — currently prevalent in almost any wire-less standards — is ill-suited for this task. Instead, filter bankbased transceivers have recently experienced a renaissance al-most four decades after their first appearance [2], since thistechnique is able to provide much enhanced frequency selec-tivity compared to OFDM. Below we discuss some aspects ofa multi-stage filter bank based transceiver, which is designedto digitally up- and downconvert the entire TVWS spectrumby sampling at an RF rate of 1.92 Msps.System Approach. The proposed transceiver uses a two-stage design as shown in Fig. 1, with 40 8MHz channels onthe left converted to a 1.92Gsps signal that is fed into theDAC/ADC on the right. While a single stage design offeredreduced cost, the interface of feeding digital RF signals intoFPGA devices requires sufficiently low rates. Further, FPGAscan only handle a number of input signals, thus providing lim-...............PPF p/sPPF s/pFBMCRX...FBMCTXp/ss/p ADCDACejΩne−jΩnstage 1stage 2Fig. 1. Proposed multi-stage TVWS filter bank transmitter(above) and receiver (below) with a polyphase filter (PPF) instage 1 and an FBMC modulator in stage 2.0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8−120−100−80−60−40−200power spectral density / dBfrequency f / GHz0 50 100 150 200 250 300 350−80−60−40−200power spectral density / dBfrequency f / MHzFig. 2. Power spectral densities after (top) stage 1 and (below)stage 2., with required masks to protect incumbent users.itations to the decimation ratios within the first stage filter.Therefore, after an initial analytic bandpass filter realised inpolyphase implementation, it is a second stage in which thefilter bank is applied within this transceiver.The filter bank design uses approximate Nyquist systemswith near-perfect reconstruction [3] and transition bands andstopbands that just satisfy the spectral mask in [1]. The result-ing power spectral densities of the stage 1 and stage 2 signalsare depicted in Fig. 2, demonstrating the requirements on boththe TVWS RF signal as well as the baseband signal betweenstages 1 and 2.Conclusion. A TVWS transceiver design has been outlined.More details will be provided during the paper presentation.References[1] S.J. Shellhammer, A.K. Sadek, and W. Zhang, “Technicalchallenges for cognitive radio in the TV white space spec-trum,” in Inf. Theory Appl. Workshop, pp. 323–323, Feb. 2009,[2] M. Bellanger and J. Daguet, “TDM-FDM transmultiplexer:Digital polyphase and FFT,” IEEE Transactions on Communi-cations, vol. 22, no. 9, pp. 1199–1205, September 1974.[3] B. Farhang-Boroujeny, “A square-root Nyquist (M) fil-ter design for digital communication systems,” IEEETrans. Sig. Proc., 56(5):2127–2132, May 2008.

A square-root Nyquist (M) ﬁlter design for digital communication systems,”

TDM-FDM transmultiplexer: Digital polyphase and FFT,”

Technical challenges for cognitive radio in the TV white space spectrum,”

http://strathprints.strath.ac.uk/41673/1/ross.pdf

Design considerations for a filter bank based TVWS transceiver

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