Broadband OFDM using 16-bit precision on a SDR platform

Author

Gifford, Steve ; Kleider, John E. ; Chuprun, Scott

Author_Institution

Integrated Inf. Syst. Group, Motorola Inc., Scottsdale, AZ, USA

Volume

1

fYear

2001

fDate

2001

Firstpage

180

Abstract

This paper discusses our development of a robust broadband model of OFDM using 16-bit fixed-point ANSI C code that can be easily ported to a variety of software defined radio (SDR) platforms. The fixed-point model allows fast runtime, low power consumption, and low cost implementation. The receiver analog to digital converter (ADC) resolution and 16-bit fixed-point issues are explored. The OFDM system consists of DQPSK encoded data symbols, pilot symbols and symbols to minimize aliasing and reduce filter requirements. The total number of OFDM subchannels is set to 256. A cyclic extension scheme is used to reduce the intersymbol interference (ISI) caused by long multipath delay spreads. The channel model consists of additive white Gaussian noise (AWGN) and continuously variable channel delay. The fixed-point OFDM algorithm was optimized with a system that uses no compensation for peak to average ratio (PAR). The model supports post-detection spatial diversity, which can be easily implemented by the multi-channel architecture provided by many SDRs.

Keywords

AWGN; OFDM modulation; analogue-digital conversion; broadband networks; delays; differential phase shift keying; diversity reception; fixed point arithmetic; intersymbol interference; multipath channels; quadrature phase shift keying; radio networks; radio receivers; software architecture; 16 bit; AWGN; DQPSK encoded data symbols; ISI reduction; PAR; SDR platform; additive white Gaussian noise; analog to digital converter; broadband OFDM; channel model; fixed-point ANSI C code; fixed-point OFDM algorithm; intersymbol interference; low cost implementation; low power consumption; multi-channel architecture; multipath delay spreads; peak to average ratio; pilot symbols; post-detection spatial diversity; receiver ADC resolution; software defined radio; symbols; variable channel delay; AWGN; Delay; Energy consumption; Intersymbol interference; OFDM; Peak to average power ratio; Power system modeling; Robustness; Runtime; Software radio;

fLanguage

English

Publisher

ieee

Conference_Titel

Military Communications Conference, 2001. MILCOM 2001. Communications for Network-Centric Operations: Creating the Information Force. IEEE

Print_ISBN

0-7803-7225-5

Type

conf

DOI

10.1109/MILCOM.2001.985786

Filename

985786