There has been an increased demand for 3G cell phones that support multiple bands of operation and are backward compatible with the 2G/2.5G standard to provide coverage where 3G networks have not yet been fully deployed. The transceiver design for such a handset becomes complicated with the need for separate transceivers for 3G and 2G/2.5G [1,2] or for multiple inter-stage receive / transmit SAW filters [3]. A single-chip transceiver that operates as a multimode multiband radio and eliminates the inter-stage receive / transmit SAW filters is presented. Figure 6.3.1 shows the block diagram of the transceiver with 7 primary and 4 diversity bands in WCDMA, and quad band in GSM. The transceiver is designed to operate in any of the UTRA bands 1 to 10, with the exception of band 7. It supports HSDPA (Cat 1-12), HSUPA (Cat 1-6), EGPRS (Classes 1-12, 30-39), and compressed mode of EGPRS / WCDMA operation. The transceiver is compliant with 3G DigRF interface 3.09.The analog / RF section of the transmitter is shown in Fig. 6.3.2. The I/Q DAC is based on oversampled current steering with 10b accuracy realized with a 6b-unary and 4b-binary segmentation. The output of the DAC is fed to a 3 rdorder Chebyshev continuous-time filter that attenuates out-of-band noise and DAC images and drives the I/Q modulator. The filter can be configured to operate in WCDMA, GMSK or EDGE mode. The I/Q modulator is a passive LO-2LO mixer. Two levels of passive switches are driven by LO and 2×LO frequencies with proper phases. This mixer configuration achieves both lower phase noise in the LO path and isolation between I and Q baseband inputs, and addresses the stringent linearity and noise requirements of GSM/WCDMA. The differential output of the I/Q modulator is converted to single-ended output using an on-chip balun. The balun output is then amplified in the driver stage and sent off-chip to the PA. The transmitter provides 80dB of gain-control range in WCDMA mode and 40dB in EDGE mode. The gain control is distributed across the chain and designed to meet the linearity and noise requirements over power-control range, while optimizing the current consumption. At high power (24 to 0dBm) a closed-loop power control scheme in the transceiver is used for accurate power control, and at lower power (0 to -57dBm) a conventional power-control scheme through the base-station is used.The architecture of the receiver front-end is shown in Fig. 6.3.3. The mixers and LO buffers are shared among several LNAs to reduce die area. The mixer outputs are connected to the virtual grounds created by the transimpedance amplifiers (TIAs) and its inputs are driven by the output current from the LNA. In this current-driven passive-mixer topology, the voltage swings at the mixer input and output are significantly reduced, resulting in improved linearity. In a passive mixer design, the noise contribution of the TIA increases as the impedance at the mixer input decreases. Therefore, an LC tank is used at the LNA cascode output with switchable capacitors to adjust the tan...

Accurate water demand forecasting is essential to operate urban water supply facilities efficiently and ensure water demands for urban residents. This study proposes an extreme learning machine (ELM) coupled with variational mode decomposition (VMD) for short-term water demand forecasting in six cities (Anseong-si, Hwaseong-si, Pyeongtaek-si, Osan-si, Suwon-si, and Yongin-si), South Korea. The performance of VMD-ELM model is investigated based on performance indices and graphical analysis and compared with that of artificial neural network (ANN), ELM, and VMD-ANN models. VMD is employed for multi-scale time series decomposition and ANN and ELM models are used for sub-time series forecasting. As a result, ELM model outperforms ANN model. VMD-ANN and VMD-ELM models outperform ANN and ELM models, and the VMD-ELM model produces the best performance among all the models. The results obtained from this study reveal that the coupling of VMD and ELM can be an effective forecasting tool for short-term water demands with strong nonlinearity and non-stationarity and contribute to operating urban water supply facilities efficiently.

This paper proposes a river stage modeling approach combining maximal overlap discrete wavelet transform (MODWT), support vector machines (SVMs) and genetic algorithm (GA). The MODWT decomposes original river stage time series into sub-time series (detail and approximation components). The SVM computes daily river stage values using the decomposed sub-time series. The GA searches for the optimal hyperparameters of SVM. The performance of MODWT-SVM models is evaluated using efficiency and effectiveness indices; and compared with that of a single model (multilayer perceptron (MLP) and SVM), discrete wavelet transform (DWT)-based models (DWT-MLP and DWT-SVM) and MODWT-MLP models. The conjunction of MODWT, SVM and GA improves the performance of the SVM model and outperforms the single models. The MODWT-based models using the SVM model enhance model performance and accuracy compared to those of using MLP model. Also, hybrid models coupling MODWT, SVM and GA improve model performance and accuracy in daily river stage modeling as compared with those combined with DWT. The MODWT-SVM model using the Coiflet 12 (c12) mother wavelet, MODWT-SVM-c12, produces the best efficiency and effectiveness among all models. Therefore, the conjunction of MODWT, SVM and GA can be an efficient and effective approach for modeling daily river stages.

A domino free 4-path time-interleaved second order sigma-delta modulator is proposed. This timeinterleaved scheme uses only one integrator channel along with incomplete integrator output terms to completely eliminate the quantizer domino which is a key limit for the practical circuit implementation of conventional multi-path time-interleaved sigma-delta modulators. In addition, the single integrator channel leads to considerable hardware reduction as well as path mismatch insensitivity, since only one global feedback path is required. As a result, the switched capacitor implementation of the 4-path time-interleaved second order sigma-delta modulator is enabled with the conventional 2-phase clocking scheme by using only 5 op-amps.

Wireless multi-hop ad hoc routing is one of the critical design factors that determine the network performance of various wireless IoT applications. IETF has standardized the point-to-point RPL (P2P-RPL) routing protocol to overcome the inefficient routing overheads of RPL. However, P2P-RPL propagates the route discovery forwarding packets throughout the whole network. P2P-RPL suffers from the high energy consumption and the huge route discovery overhead in low-power and lossy networks (LLNs). In this paper, we propose a novel Location-Aware P2P-RPL (LA P2P-RPL), which achieves the energy-efficient P2P data delivery without reducing the networking reliability. The proposed algorithm introduces the Impulse-Response UWB (IR-UWB) based cooperative multi-hop self localization algorithm and the Location-Aware P2P-RPL algorithm for Indoor IR-UWB based networks. To increase the localization accuracy, smartphone based Inertial Navigation System (INS) with particle filtering is used in indoor multi-hop environments. The performance evaluations for Location-Aware P2P-RPL algorithm are compared with the traditional P2P-RPL and the ER-RPL algorithm to show the significant performance improvements for route discovery overheads and energy consumptions in LLNs.