Yuen Sam Kwok

UWB ranging with energy detectors using ternary preamble sequences

In this paper, a new pulse-based UWB system is proposed with low power ranging. The ternary sequence based common signaling is proposed to support power efficient energy detectors, differential detectors, and coherent detectors simultaneously. The preamble for ranging is designed to have good autocorrelation properties. The on-off keying based power efficient modulation is combined with chip mapping/spreading to provide robust system performance even in a multipath fading channel. Furthermore, a low complexity energy detection receiver structure is elaborated for leading edge detection in a multipath rich channel. System simulations are performed to demonstrate the promising performance of the proposed system

UWB piconet interference suppression using clustered ternary orthogonal signaling scheme

This paper describes a transceiver design based on clustered ternary code sequences as a form of modulation in order to achieve good interference suppression with a low cost and low complexity implementation. The use of ternary code sequences allows for flexible receiver designs, so that the same transmitted signals can be detected by coherent, differential and non-coherent receivers. By applying cyclic-shifts on the base ternary code sequence, an inherent coding gain from orthogonal signaling can be achieved without any external channel coder. Our pulse-clustering proposal makes use of both time and code domains for greater SOP suppression than the pure time domain scheme commonly used in pulse position modulation (PPM). In addition, pulse-clustering transmission of ternary chips enables a low sampling rate at the receiver.

Video transmission system based on visible light communication

White LED is deemed to be the new candidate for next generation high efficiency/brightness lighting device with power consumption reduced to less than 80%. Communication functionality can be integrated into energy-saving white LED lighting structure / infrastructure to enable low-cost / low-power high-speed short-range wireless access. In this paper, we demonstrate a visible light communication prototype for video transmission at 10 Mb/s. The prototype is based on a commercial phosphorescent white LED and on-off key (OOK) modulation, without a blue filter on the receiver side. The sizes of the transmitter and the receiver are small, while a communication distance of more than 1.2 meters is achieved.

A Low Complexity Mapping and Modulation Scheme for IEEE 802.15.4b

We detail a code mapping scheme designed especially for devices in the enhanced wireless personal area networks operating in both the 868 MHz and 915 MHz bands for the emerging IEEE 802.15.4b standard. This carefully designed coding scheme, called cyclic odd bit inversion length 16 (COBI-16), meets all the following three essential criteria: (a) no spikes in the frequency spectrum, (b) low complexity correlation operations and (c) simple frequency offset and DC compensation operations. The scheme is tested in both AWGN and Rayleigh fading (flat and frequency selective) channels. Both coherent and non-coherent demodulations are investigated. Also investigated are the synchronous false alarm rate and synchronous miss rate in the AWGN channel. The results show that the scheme conforms to all the stringent requirements defined by the IEEE 802.15.4b protocol. The scheme has been accepted by the IEEE 802.15.4b task group as the standard for data transmission.

Performance Analysis of Channel Coding Schemes with Blind Channel Estimation

Blind channel estimation (BCE) of multi channel FIR filters is an issue arising in e.g. mobile communication systems using digital signaling. It also arises in the presence of frequency selective fading, when training (reference/pilot) symbols are unavailable. In this contribution we analyze the performances of two types of channel coding schemes; turbo coding and serial concatenated convolutional coding (SCCC), with BCE. The BCE technique used here is a second order statistics algorithm based on subspace decomposition (SSD). The coding schemes are combined with this BCE technique to characterize a realistic scenario: in that we do not assume the transmitted signal to be white. Two types of blind equalizers are investigated: the zero forcing and the minimum mean squared error equalizers. The results show that the turbo-coding scheme performs better than the SCCC scheme by an average of 1-1.5 dB

Modulation and Code Mapping Scheme for High Rate Transmission for IEEE 802.15.4b

IEEE 802.15.4b is an enhanced standard to the IEEE 802.15.4, addressing the needs for high-data rate transmission using 868 or 915 MHz band in the wireless personal area networks. This paper details a modulation and code mapping scheme designed specifically for the standards high rate transmission schemes operating in the 868 MHz and 915 MHz bands; which leads to efficient transmission and low implementation complexity. The code mapping scheme is called Quadrature Cyclic Odd Bit Inversion length 16 or Quad COBI-16. Among the schemes desirable properties is that the total phase rotation in the I/Q plane accumulates to 0 degree over the complete symbol. The scheme is tested in both AWGN and Rayleigh frequency selective fading channels. The results show that it conforms to all the stringent requirements defined by the standard.

A cyclic odd bit inversion code mapping and modulation scheme for the IEEE 802.15.4b 868 MHz band

We detail a cyclic odd bit inversion length 16 (COBI-16) code mapping and modulation scheme designed especially for devices in the enhanced wireless personal area networks (WPAN) operating in the 868 MHz for the emerging IEEE 802.15.4b standard. This COBI-16 scheme has been accepted and incorporated in the draft IEEE 802.15.4b standard. This carefully designed coding and modulation scheme meets all the following three essential criteria: (a) no spikes in the frequency spectrum, (b) low complexity correlation operations and (c) simple frequency offset and DC compensation operations. The transmitted signal meets all the IEEE standards stringent PSD mask requirements. The system is tested in both AWGN and Rayleigh fading (flat and frequency selective) channels. Both coherent and non-coherent demodulations are investigated. Also investigated are the synchronous false alarm rate and synchronous miss rate in the AWGN channel

Turbo Coding with Blind Channel Estimation in a SIMO FIR Channel

This paper addresses the issue of blind channel estimation (BCE) in a SIMO FIR channel. This is an issue arising in e.g. mobile communication systems using digital signaling. It also arises in the presence of frequency selective fading, when training (reference/pilot) symbols are unavailable. In this contribution we analyze the performances of a 1/2 and 1/3 rate turbo code of various frame lengths with two types of second order statistical BCE algorithms. The first algorithm is the subspace decomposition algorithm (SSDA) and the second is the outer product decomposition algorithm (OPDA). The object of this contribution is to investigate the performances of the turbo coded system with these two types of BCE algorithms in order to characterize a possible and realistic scenario. The results show that the turbo coded schemes using the SSDA can outperform the scheme using the OPDA by as mush as 7 dB.

Low Complexity 16-Ary Ternary Orthogonal Keying for UWB Communications

In this paper, a pulse UWB system based on 16-ary ternary orthogonal keying (TOK) is proposed for low power low data rate wireless personal area networks (WPAN). The novel ternary sequence based common signaling in the UWB system is proposed to support efficient implementation for both simple energy detectors and complex coherent detectors. Three variants on different pulse compression and clustering are also discussed and simulations have been conducted for both additive white Gaussian noise channels, UWB line-of-sight and non-line-of-sight fading channels. The results have demonstrated the superior performance of the proposed UWB system over other systems.

Cyclic Odd Bit Inversion Code Mapping and Modulation Scheme for IEEE 802.15.4b 915MHz Wireless Personal Area Networks

We detail a cyclic odd bit inversion length 16 (COBI-16) code mapping scheme designed especially for devices in the enhanced wireless personal area networks operating in the 915 MHz for the emerging IEEE 802.15.4b standard. This carefully designed coding scheme meets all the following three essential criteria: (a) no spikes in the frequency spectrum, (b) low complexity correlation operations and (c) simple frequency offset and DC compensation operations. The scheme is tested in both AWGN and Rayleigh flat and frequency selective fading channels. Both coherent and noncoherent demodulations are investigated. Also investigated are the synchronous false alarm rate and synchronous miss rate in the AWGN channel. The results show that the scheme conforms to all the stringent requirements defined by the IEEE 802.15.4b protocol. The scheme has been accepted by the IEEE 802.15.4b task group as the standard for data transmission