John F.M. Gerrits

Principles and limitations of ultra-wideband FM communications systems

This paper presents a novel UWB communications system using double FM: a low-modulation index digital FSK followed by a high-modulation index analog FM to create a constant-envelope UWB signal. FDMA techniques at the subcarrier level are exploited to accommodate multiple users. The system is intended for low (1–10 kbps) and medium (100–1000 kbps) bit rate, and short-range WPAN systems. A wideband delay-line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the UWBFM receiver. This unusual approach permits multiple users to share the same RF bandwidth. Multipath, however, may limit the useful subcarrier bandwidth to one octave. This paper addresses the performance with AWGN and multipath, the resistance to narrowband interference, as well as the simultaneous detection of multiple FM signals at the same carrier frequency. SPICE and Matlab simulation results illustrate the principles and limitations of this new technology. A hardware demonstrator has been realized and has allowed the confirmation of theory with practical results.

Low-Complexity Ultra-Wide-Band Communications

Low-complexity low-power ultra-wide-band (UWB) radios are required for low data rate (LDR, < 100 kbps) short- range applications. Potential low-power air interface candidates are impulse radio UWB and FM-UWB. The use of simple (noncoherent) radio architectures, a low supply voltage and duty cycling pave the way to low power consumption. Interference mitigation is an important requirement for todays UWB receivers. Processing gain and filtering may be applied in the physical layer, whereas detect and avoid strategies work at MAC level. Constant-envelope FM-UWB uses high modulation index analog FM for spreading. Instantaneous despreading in the receiver, combined with processing gain make this system an interesting option for robust LDR personal area network systems.

A Short Range, Low Data Rate, 7.2 GHz-7.7 GHz FM-UWB Receiver Front-End

A 9 mW FM-UWB receiver front-end for low data rate ( <50 kbps), short range ( <10 m) applications operating in the ultra-wideband (UWB) band centered at 7.45 GHz is described in this paper. A single-ended-to-differential preamplifier with 30 dB voltage gain, a 1 GHz bandwidth FM demodulator, and a combined (preamp/demodulator) receiver front-end were fabricated in 0.25 mum SiGe:C BiCMOS and characterized. Measured receiver sensitivity is -85.8 dBm while consuming 9 mW from a 1.8 V supply, and -83 dBm consuming 6 mW at 1.5 V. 15-20 m range line-of-sight in an indoor environment is realized, justifying FM-UWB as a robust radio technology for short range, low data rate applications. Multi-user and interference capabilities are also evaluated.

Low-Complexity Ultra Wideband Communications

Low-complexity, low power UWB radios are required for LDR short-range applications. Potential low power air interfaces candidates are impulse radio UWB and FM-UWB. FM-UWB is a constant-envelope UWB communication system using double FM: digital FSK followed by high modulation index analog FM to create a constant-envelope UWB signal. The system is intended for low data rate (< 100 kbps), short-range (< 10 m) personal area network systems. Due to its simple architecture, FM-UWB radio will be low cost and have low power consumption

A Wideband FM Demodulator for a Low-Complexity FM-UWB Receiver

A wideband FM demodulator circuit for a low-complexity UWB communications system based upon double FM techniques is presented. The receiver demodulates the FM-UWB signal without frequency translation. The FM demodulator presented here covers the low band (3.1-5 GHz) and consumes 10 mW. The 0.72 mm2 demodulator IC is implemented in 0.18 mum Si-Ge BiCMOS technology

A 9mW high band FM-UWB receiver front-end

A low-power FM-UWB receiver front-end for low data rate (100 kbps) short-range (<10 m) applications operating in the upper UWB band at 7.45 GHz is described. The front-end comprises a 21 dB gain preamplifier and a 1GHz bandwidth FM demodulator. The measured receiver sensitivity is -86.8 dBm while consuming 9 mW from a 1.8 V supply and -84.3 dBm is achieved at 6 mW power consumption. The 0.88 mm2 active area circuit is implemented in 0.25 mum SiGe:C BiCMOS.

Energy-efficient wireless front-end concepts for ultra lower power radio

Two ultra low power wireless concepts are described in this paper. A high data rate receiver demonstrator consisting of LNA, sub-harmonic I/Q mixer and transimpedance IF amplifiers realizes an energy consumption of 1.75 nJ/bit at 10 Mbit/s in the 17 GHz band. A high-band FM-UWB receiver demonstrator, which achieves a measured sensitivity of -84.3 dBm at 100 kbit/s while consuming just 6 mW is also described.

Multipath Behavior of FM-UWB Signals

This paper analyzes the multipath behavior of FM-UWB signals and more particularly the effect of frequency selective fading upon the sub-carrier signal level in the FM-UWB receiver. The performance with CM1-CM4 channels is investigated and illustrated with MATLAB simulation results. Good and bad propagation channels for FM-UWB communication systems are identified. The effect of frequency selective fading is mainly determined by the channel transfer at the edges of the FM-UWB signals bandwidth. It is shown that multipath is beneficial for the FM-UWB receiver performance.

UWB Transmission and MIMO Antenna Systems for Nomadic Users and Mobile PANs

Personal Area Networks (PANs) are expected to play an important role in future mobile communications and information systems. A proliferation of low data rate sensor and control devices is envisioned. These devices must be able to communicate across various networks in order to provide seamless end-to-end service. At the physical and link level, several factors are critical in order to realize a nomadic PAN: co-existence with other systems, efficient use of increasingly scarce spectrum resources and capacity, robustness in the presence of interference, as well as, the availability of low cost individual user devices. In this paper, we examine a concept for nomadic PANs employing low cost, low data rate ultra wideband (UWB) communication links between personal devices and a handset, or mobile bridge, coupled with a multiple input multiple output (MIMO) antennas for communication from a mobile bridge to other networks. Key issues are identified and potential capacity and quality-of-service (QoS) enhancements are evaluated.

FM-UWB: A Low-Complexity Constant Envelope LDR UWB Approach

This paper presents a novel low complexity, constant envelope UWB communication system for personal network and sensor network applications: FM-UWB. FM-UWB uses double FM: digital FSK followed by high modulation index analog FM to create a constant envelope UWB signal. FDMA techniques at the sub-carrier level may be exploited to accommodate multiple users. A wideband delay line FM demodulator that is not preceded by any limiting amplifier constitutes the key component of the FM-UWB receiver. This allows multiple users to share the same RF bandwidth. The system is intended for low data rate, short-range (< 10 m) applications. Due to its simple architecture, FM-UWB radio will be low cost and have low power consumption.