Dual Carrier Modulation using Improved Data Allocation Scheme

Abstract

Purpose: The increasing need for high speed low power data transmissions over frequency selec-tive fading channels has drawn attention to suggest dual carrier modulation (DCM) for multiband orthogonal frequency division multiplexing (OFDM) transceiver for ultra wideband (UWB) wireless personal area network (WPAN).
Design/Methodology/Approach: Under frequency selective fading channel conditions, the de-coder is not su_cient enough to decode the transmission bits of severely attenuated data tones hence,we suggest DCM for a multiband OFDM transceiver due to its multiple capability of providing both frequency diversity and coding gain. It also resulted in low bit-error-rate (BER) at a given signal-to-noise ratio (SNR) when compared to conventional multiband OFDM system. In order to achieve an optimised BER, DCM transforms four re-ordered bits into two quaternary phase shift keying (QPSK) symbols and further transforms to two 16-quadrature amplitude modulation (16-QAM) like symbols with a suitable mapping technique and at the receiver end they are decoded with maximum likelihood (ML) decision rule. After performing the transformation, the outage probability and average BER expressions are derived to analyse the system performance.
Findings: DCM is suitable for high data rate transmission and is immune to frequency selective fading. The outage and BER performance outstands over conventional multiband OFDM transceiver due to the inclusion of DCM mapping.
Practical Implications: It is widely used in WPANs like high de_nition multimedia interface and wireless universal serial bus (WUSB).
Originality/Value: This paper derives novel closed-form outage probability and a tight upper bound on average BER expressions for DCM based multiband OFDM UWB transceiver over frequency selective Nakagami-m fading channels, for any arbitrary value of m. For this, moment generating function (MGF) of sum of squared, identical independently distributed, Nakagami-m random variables are used. Further the system performance is also validated for the case of exponential decaying PDP and the simulation results are provided to check the accuracy of the derived expressions.