We introduce geo-regioning as a method to achieve rough localization in asynchronous UWB networks. The approach is to localize the transmitter position by means of the multipath components in the received channel impulse response (signature). To show the principle feasibility of this approach a first regioning algorithm is introduced and tested with measured data. Therefore, a measurement campaign in a rich multipath environment has been performed. A high number of signatures originating from different regions in a room have been collected. The regioning algorithm presented here is based on the a priori knowledge of the average power delay profiles of the different regions. The performance results show that almost all regions can be localized at reasonable SNR and error probability. We conclude that the geo-regioning approach is a promising alternative or supplement to classical time of arrival based approaches in UWB networks.
We consider Ultra-Wideband Impulse Radio (UWB-IR) Low Data Rate (LDR) applications where a more complex Cluster Head (CH) communicates with many basic Sensors Nodes (SN). At receiver side, noncoherent Energy Detectors (ED) operating at low sampling clock, i.e., below 300kHz, are focused. Drawback is that EDs suffer from significant performance losses with respect to coherent receivers. Pulse Repetition Coding (PRC) is a known solution to increase receiver performance at the expense of more transmit power. But in LDR systems known PRC is very inefficient due to the low receiver sampling clock. Boosting transmit power is not possible due to Federal Communications Commission's (FCC) power constraints. Hence, we present a modified PRC scheme solving this problem. Modified Repetition Coded Binary Pulse Position Modulation (MPRC-BPPM) fully exploits FCC power constraints and for EDs of fixed integration duration is optimal with respect to Bit Error Rate (BER). Furthermore, MPRC-BPPM combined with ED outperforms SRAKE receivers at the expense of more transmit power and makes ED's performance robust against strong channel delay spread variations.
Multiple input multiple output (MIMO) communication systems are popular for achieving high rates, but at the same time they suffer from high implementation cost. Hence, their adoption to future distributed systems, e.g., sensor networks, is stalled due to the stringent cost and power constraints of the node design. One solution is the combination of MIMO systems with nonlinear detectors, i.e., amplitude or phase detectors, which are known for their cheap implementation cost and low power consumption. We provide semi-analytical results for achievable rates in MIMO systems that use nonlinear detectors for the fast fading channel, as well as outage probabilities for the same detectors in the slow fading case.
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