Cyclic bit loading for adaptive OFDM in narrowband power line communications

Abstract

This paper considers an adaptive orthogonal frequency-division multiplexing (OFDM) transmission scheme for narrowband (NB) power line communication (PLC). The NB PLC channel is found to show strong cyclostationary characteristics due to the periodic mains voltage. However, conventional systems do not use these time-varying channel features. An improvement of the performance is achieved by exploiting the cyclic properties of the channel. Therefore, adaptive bit and power loading methods are of great interest for PLC. In this work, we will evaluate a cyclic loading method for an OFDM system in the CENELEC A-band. Our analysis is based on noise measurements at three different locations over an observation time of 23 hours. Our contribution includes an OFDM system model comprising both additive noise and channel attenuation. Furthermore, we present a method for limiting the amplitude and power spectral density to comply with narrowband regulations. In conclusion, our proposed method achieves a lower bit error rate at all locations. The improvement reaches up to a 10 2 times lower bit error rate compared to non-adaptive carrier allocation at the same data rate.

Resource Allocation in HS-OFDM-based PLC Systems: A Tutorial

“…With the carried out discussion and the case study that proved the correctness of the resource allocation procedure as presented in this paper, concepts and definitions have been addressed in a way such that one can easily understand and implement resource allocation techniques in multicarrier-based communication systems operating in the baseband, which can be easily extended to passband systems. For results on specific resource allocation techniques and discussions on individual aspects of resource allocation in PLC systems, we encourage the reader to consult works such as [6]- [8], [31], [32], [59], [60], [62].…”

“…Therefore, the BER upper bound from (35) can only be used after performing the resource allocation procedure, as it depends on results from the latter. Alternatively, approximations for the BER at a subchannel given noise power and number of allocated bits, which is not known a priori, are used in the formulation of [59]- [61] in an extra step of a resource allocation technique, and validated in a practical demonstration in [62]. In this work, we adopt SER-based approach for dealing with a simplified resource allocation problem and focusing on a clear presentation of important aspects of the resource allocation procedure.…”

Cyclic Signals and Systems in Power Line Communications

“…By identifying this result with the cyclic decomposition of the mean in ( 4), ( 61) can be reached, concluding the proof. Property 5: When a stationary signal excites a LPTV system, the cyclic spectra of the CS signal at the output can be expressed in terms of the input signal PSD and the system cyclic response as in (60).…”

“…and by identifying terms in the FS expansion of the cyclic autocorrelation, see (7), it leads to 71) which defines the relation between the cyclic coefficients of the CS output signal autocorrelation with the input signal autocorrelation and the LPTV system response. Since cyclic spectra S α Y (f ) form a transform pair with the autocorrelation cyclic coefficients R α Y (u), it is possible to obtain them by applying some FT properties and simple algebra to derive (60).…”

“…When a stationary signal, with a PSD S X (f ), excites this modulating system, the output signal is CS and has the cyclic spectra (see (60))…”