Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Symbol Error Rate Calculation for Alamouti Space Time Coded OFDM in Direct Conversion Receivers

Abstract—In this paper we present an analytical approach to evaluate the M-QAM symbol error rate (SER) of Alamouti space time coded OFDM direct conversion receivers subject to carrier frequency offset (CFO), channel estimation errors, outdated channel state information and flat receiver I/Q imbalance in Rayleigh time and frequency selective fading channels. Based on correct modeling of the correlation between channel estimates and received signals with carrier frequency offset and receiver I/Q imbalance, the SER can be numerically evaluated by averaging symbol error rates on different subcarriers using an analytical expression of double integrals. The results illustrate that the analysis can approximate the simulative performance very accurately if the power delay profile of fading channels, the receiver I/Q imbalance parameters and carrier frequency offset are known. I

Channel-Matched Receiver for Throughput Enhancement in OFDM

Abstract: In this paper we present two throughput enhancing detection schemes for OFDM, all using the Frequency Domain Channel Length Indicator (FCLI) algorithm for improved channel estimation and joint mobile channel impulse response length estimation. At first we introduce a novel optimized detection scheme for guardinterval-free OFDM reception. In contrast to traditional OFDM, omitting the guard interval (GI) can achieve a significant enhancement of throughput and spectral efficiency. Performance of GI-free OFDM is limited by intersymbol & interchannel interference (ISI & ICI). By applying our novel optimized ISI-ICI cancellation algorithm, we show that performance loss of GI free OFDM can be reduced to a negligible amount. As an alternative to GI free OFDM we present an FCLI-based GI adaptation scheme and compare both approaches in terms of system throughput enhancement. 1

Throughput Enhancement for MIMO OFDM using Frequency Domain Channel Length Indicator and Guard Interval Adaptation

Abstract — In this paper a novel scheme for OFDM guard interval adaptation is presented, that uses the Frequency Domain Channel Length Indicator (FCLI) algorithm for estimating the length of the channel impulse response (CIR). In contrast to other schemes, our method does not require any time averaging to estimate the CIR length and is applicable in SISO and MIMO OFDM, with and without spectrum mask. By estimating the CIR length in an ad hoc manner our results show, that it is possible to instantaneously react on changing propagation environments and to significantly increase throughput without decreasing detection performance. I

Bit Error Rate Calculation for OFDM Direct Conversion Receivers with Synchronization and Channel Estimation Imperfections

Abstract — In this paper we present an analytical approach to evaluate the M-QAM bit error rate (BER) of OFDM direct conversion receivers subject to carrier frequency offset (CFO), channel estimation error, outdated channel state information and flat receiver I/Q imbalance in Rayleigh time and frequency selective fading channels. Based on correct modeling of the correlation between channel estimates and received signals with carrier frequency offset and receiver I/Q imbalance, the bit error rate can be numerically evaluated by averaging bit error rates on different subcarriers using an analytical expression of triple integrals. The results illustrate that the analysis can approximate the simulative performance very accurately if the power delay profile of fading channels, the receiver I/Q imbalance parameters and carrier frequency offset are known. I

Bit Error Rate Calculation for OFDM with Synchronization Errors in Time and Frequency Selective Fading Channels

Abstract — In this paper we present an analytical approach to evaluate the bit error rate (BER) of OFDM systems subject to carrier frequency offset (CFO) and channel estimation error in Rayleigh flat fading as well as in time and frequency selective fading channels. Based on correct modeling of the correlation between channel estimates and received signals with carrier frequency offset, the bit error rate can be numerically evaluated by averaging bit error rates on different subcarriers using an analytical expression of double integrals. The results illustrate that the analysis can approximate the simulative performance very accurately if the power delay profile of fading channels and carrier frequency offset are known. I

OFDM Link Performance Analysis under Various Receiver Impairments. Accepted for publication

Abstract — In this article, we present a methodology for OFDM link capacity and bit error rate calculation that jointly captures the aggregate effects of various real life receiver imperfections such as: carrier frequency offset, channel estimation error, outdated channel state information due to time selective channel properties and flat receiver I/Q imbalance. Since such an analytical analysis is still missing in literature, we intend to provide a numerical tool for realistic OFDM performance evaluation that takes into account mobile channel characteristics as well as multiple receiver antenna branches. In our main contribution, we derived the probability density function (PDF) of the received frequency domain signal with respect to the mentioned impairments and use this PDF to numerically calculate both bit error rate and OFDM link capacity. Finally, we illustrate which of the mentioned impairments has the most severe impact on OFDM system performance. I