Sonom Olonbayar

Synchronisation performance of wireless sensor networks

Ultra Wideband (UWB) has been gaining growing research and industry interests in many different areas of wireless communications. Among them using UWB as a radio interface for wireless sensor network is of high interest due to its precise localisation and low power consuming capabilities. In this paper we carry out quantitative analysis into the synchronisation performance of UWB when it operates under usual wireless channel environments. Simulation results confirm that coherent receiver needs around 10 dB less signal to noise ratio to achieve synchronisation compared to the noncoherent detection. Higher spreading factors lead to noticeable improvement for both coherent and noncoherent detection.

Efficient Synchronization Method for IR-UWB 802.15.4a non-coherent Energy Detection Receiver

Using UWB for wireless short range, low rate communication is attracting growing interest due to its low power consumption and very high bandwidth. Moreover, it is able to offer accurate localization in the range of few centimeters. Regarding these qualities, it is desirable to design a IR-UWB transceiver which consumes as few power as possible when it is applied for battery driven wireless sensors. For this reason a baseband design and performance of IR-UWB receiver based on the standard IEEE.802.15.4a was investigated in this paper with particular emphasis on energy efficient synchronization and preamble detection.

Performance and design of IR-UWB transceiver baseband for wireless sensors

Using UWB for wireless short range, low rate communication has been attracting growing interest due to its low power consumption and very high bandwidth. Moreover, it is able to offer accurate localization in the range of few centimeters. Recognising these qualities, it is desirable to design IR-UWB transceiver which can draw minimum possible power when it is applied for battery driven wireless sensors. For this reason, in this paper, baseband design and performance of IR-UWB transceiver based on the standard IEEE.802.15.4a was investigated with particular emphasis on reducing power consumption. Synchronization algorithm that achieves 16 ns is presented and its performance is very promising offering nearly 100% synchronization for as low SNR as 8 dB. Different resolutions of analogue to digital converter (ADC) are investigated to find out the optimum with respect to power consumption and performance. 4 bit ADC was found to be the most optimal for the sample rate of 62.4 MHz. BER performance of pulse position modulation was evaluated under realistic channel conditions with multipath components.

Evaluation and optimization of robustness in the IEEE 802.15.4a standard

In this paper, we introduce ways to improve the robustness by lowering the packet loss rates of transmissions using ultra-wideband impulse radio (UWB-IR). It has been shown that the packet loss rate caused by erroneous synchronization can be tremendously decreased compared to the preamble specified in the standard IEEE 802.15.4a by our approach. These improvements are particularly intended for low-power, low-complexity transceivers operating in environments with harsh multi path propagation and high noise levels, such as industrial control. These improvements include novel ways for receiver implementation to reduce detection errors for low-power energy detection receivers with slow sampling rates. We also introduce a modified preamble that significantly reduces packet loss caused by failed preamble synchronizations We evaluate our improvements by simulation. Our approach to receiver implementation enables receiver to achieve the same packet loss rate at a signal-to-noise ratio (SNR) 10 dB lower than traditional receiver designs.

IR-UWB single-chip transceiver for high-band operation compliant to IEEE 802.15.4a

This paper describes a monolithic integrated single-chip transceiver intended for impulse radio (IR) - Ultra-wide Band (UWB) applications compliant to the IEEE 802.15.4a standard. The transceiver operates in the higher UWB band on the mandatory channel #9 (7.9872 GHz). The implemented nominal data rate is 850 kb/sec. The presented chip consists of the entire RF-front-end, 6-bit-resolution successive approximation register (SAR) analogue-to-digital converter (ADC), and the baseband processor running with a clock of 31.2 MHz. The analogue frontend can be further segmented into a pulse generation and transmit part and a quadrature direct down conversion receiver part, whereas both parts share a frequency synthesizer based on an integer-N phase-locked loop (PLL). The impulse generation is based on the gated oscillator principle allowing required on-off keying (OOK) as well as binary phase shift keying (BPSK). While the receiver supports both, coherent and non-coherent impulse detection, here only non-coherent operation will be presented. The baseband processor part contains a separated 499.2 MHz clocked block for transmitter control and provides a serial peripheral interface (SPI) for data exchange with an external micro controller. The presented chip was fabricated in a 0.25 μm SiGe:C BiCMOS technology occupying a Si area of 3.25 - 3.25 mm2.

A 6 bit and a 7 bit 80 MS/s SAR ADC for an IR-UWB receiver

A 6 bit and a 7 bit successive approximation register (SAR) analog-to-digital converter (ADC) with conversion rates of up to 80 MS/s are presented in this paper. They will be used in an impulse-radio ultra-wideband (IR-UWB) receiver. The architecture with a switched-capacitor (SC) digital-to-analog converter (DAC) is applied due to its low power consumption. The 6 bit analog-to-digital converter applies the classic switching algorithm which is extended to 7 bit with a minor change to the analog part of the converter. A new kind of flip-flops is used in the SAR which enables synchronous operation during the conversion phase. The integrated circuit is realized in the 250 nm SiGe BiCMOS technology SGB25V of IHP. The cores of both analog-to-digital converters occupy a chip area of 0.36 × 0.28 mm2 and consume 5 mA from a 2.6 V supply.

High-band ultra-wideband transmitter for IEEE 802.15.4a standard

This paper presents a monolithically integrated ultra wideband direct up conversion transmitter designed in accordance with IEEE 802.15.4a standard. The transmitter operates in the higher UWB band in eight communication channels. It supports the burst position and the binary phase-shift keying modulation schemes and provides a modulated impulse sequence with a pulse repetition frequency up to 499.2 MHz. The transmitter is fabricated in a 0.25 μm BiCMOS technology and occupies a silicon area of 1.75×1.55 mm2.

Performance and implementation of a multi-rate IR-UWB baseband transceiver for IEEE802.15.4a

Design, simulation, implementation and performance of IR-UWB baseband conforming to IEEE802.15.4a are discussed. The baseband can support various data rates such as 850 Kb/s, 6.81 Mb/s and 27.24 Mb/s. The design and parameter selection were considered carefully taking into account all possible imperfections that IR-UWB high frequency signal can experience. Energy detection receiver employing a comparator clocked at 499.2 MHz was adopted for the digitisation. Using I and Q path both positive and negative pulses were detected with a high reliability leading to a very good synchronisation performance. Simulation results confirm that the synchronisation is very robust being always correct for office NLOS environment and a large clock deviation between transmitter and receiver. The algorithm presented in this paper was implemented with discrete components, FPGA and signal generators. Experimental results show a good agreement with the simulation for all the data rates and the implemented baseband offers around six meter communication range tested along with a high frequency frontend from discrete components.

Design and ASIC implementation of an IR-UWB-baseband transceiver for IEEE 802.15.4a

Using UWB for wireless short range, low rate communication is attracting growing interest due to its low power consumption and very high bandwidth. Moreover, it is able to offer accurate localization in the range of few centimeters. Considering these qualities, it is desirable to design an IR-UWB transceiver which consumes as small power as possible when it is applied for battery driven wireless sensors. For this reason, an IR-UWB transceiver based on the standard IEEE.802.15.4a was investigated in this paper with particular emphasis on its implementation, power consumption and area need for both FPGA and ASIC solutions. This paper presents results obtained with real hardware.

Performance of UWB and its suitability for wireless sensors

Ultra-wideband (UWB) has become one of the key technologies in wireless communication industries. In this paper we discuss and evaluate the performance of UWB under different channel conditions when it is applied for wireless sensors. The simulation was carried out for various detection and modulation schemes. Simulation results confirm that UWB with coherent detection outperforms the noncoherent detection the difference being 10dB in SNR to achieve the same performance. Coded UWB improves the performance by another 2dB. Low rate UWB performs better than the high rate one.