A synopsis of modulation techniques for wireless infrared communication (original) (raw)
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Wireless Infrared Communications
The use of infrared radiation as a medium for high-speed, short-range wireless digital communication is discussed. Currently available infrared links and local-area networks are described. Advantages and drawbacks of the infrared medium are compared to those of radio and microwave media. Physical characteristics of infrared channels using intensity modulation with direct detection (IM/DD) are presented, including path losses and multipath responses. Natural and artificial ambient infrared noise sources are characterized. Strategies for designs of transmitters and receivers that maximize link signal-to-noise ratio (SNR) are described. Several modulation formats are discussed in detail, including on-off keying (OOK), pulse-position modulation (PPM), and subcarrier modulation. The performance of these techniques in the presence of multipath distortion is quantified. Techniques for multiplexing the transmissions of different users are reviewed. Performance of an experimental 50-Mb/s on-off-keyed diffuse infrared link is described.
Digital pulse interval modulation for IR communication systems?a review
International Journal of Communication Systems, 2000
This paper presents a brief review of infrared communications systems, modulation techniques and in particular, a digital pulse modulation scheme known as digital pulse interval modulation (DPIM) for infrared (IR) communication systems employing intensity modulation with direct detection (IM/DD). DPIM code characteristics, power spectral density and error probability in terms of the packet error rate are discussed. Performance comparison is made with that of on}o! keying (OOK) and pulse position modulation (PPM). For comparison, relevant expressions for both OOK and PPM are also presented. Using a threshold-detector-based receiver, we show that DPIM outperforms both OOK and PPM in terms of power e$ciency and PPM in terms of bandwidth e$ciency, by taking advantage of its inherent variable symbol duration. However, using a maximum-a posteriori (MAP) detector it provides marginally inferior error rate performance compared with PPM.
Experimental results of a pulse position modulation infrared transceiver
1996
This paper presents experimental results of an Infrared transceiver for diffuse systems based on Pulse Position Modulation. The implementation followed the upcoming IEEE 802.11 specification. This transceiver was developed within the ESPRIT.6892 POWER (Portable Workstation for Education in Europe) project, partially funded by the European Commission.
Optical Wireless Communications, 1999
The performance of optical wireless transmission systems is mainly impaired by the shot noise induced by ambient light, interference produced by artificial light sources, transmitted optical power limitations due to high path losses and channel bandwidth limitations due to inter-symbol interference (ISI) produced by the multipath dispersion of the optical signal. The contribution of these factors to the performance evaluation of infrared links have only been addressed independently and the combined effect of these channel impairments was not presented yet. The work presented in this paper extends the previous analysis by taking into account the combined effects of both optical noise (shot noise and interference) and channel impulse response. A simulation package was used to determine the indoor optical channel impulse response due to the propagation losses and multipath dispersion under various room geometries and emitter/receiver parameters. The contribution of the interference produced by incandescent and fluorescent lamps was done through the utilisation of analytical models. The penalty introduced by these channel characteristics was quantified considering the modulation schemes usually considered for optical wireless communication systems: 2-, 4-and 16-PPM (pulse position modulation) at bit rates from 1 to 10 Mbps.
Infrared wireless communication using spread spectrum techniques
IEE Proceedings - Optoelectronics, 2000
The performance of nondirected line-of-sight indoor wireless infrared communication systems is mainly affected by ambient light-induced shot noise, multipath dispersion and interference produced by artificial light sources. Application of spread spectrum techniques to combat multipath dispersion and artificial light interference is presented, with bit error rate analysis considering these two effects. Experiments were carried out to verify the bit error rate analysis and to demonstrate the practical performance of a spread spectrum system. For the lineof-sight link investigated both experimental and analytical results show that a spread spectrum system operating at 2 Mbit/s and with spreading factor 3 1 suffers a power penalty of less than 0.5 optical dB due to multipath dispersion, and less than one optical dB penalty is incurred under the influence of 10 dB artificial light interference.
Performance Analysis of Baseband Modulation Techniques for Visible Light Communication
Optical wireless communication systems employ IM/DD. This is basically modulating the intensity of the signal in order to transmit information. This paper concentrates on baseband pulse time modulation techniques that are used to modulate data for optical wireless communication. Initially, Visible Light Communications used OOK (On-Off Keying) and PPM(Pulse position Modulation) but in recent times there has been an increase in the number of modulation techniques that are bandwidth and power efficient, like Digital Pulse Interval Modulation (DPIM) and Dual-header Pulse Interval Modulation (DH-PIM). In this paper OOK, PPM, DPIM and DH-PIM are compared in terms of spectral efficiency, optical power requirements, bandwidth requirements, transmission capacity, packet transmission rates and peak-average-power-ratio (PAPR).
Hybrid transmitter design for infrared wireless link
2003
Abstract An optical transmitter employing hybrid eye-safe infrared light-emitting diodes for the wireless link is presented. Effectiveness for attaining wide field of view (up to 55 half-angle) and high speed up to 67 MHz to support different intensity modulation scheme is confirmed by both simulation and experiment.
Advanced technologies for infrared wireless indoor local area networks
2000
Abstract The main degrading factor of infrared communication systems is the shot noise due to ambient light. Due to the directional nature of both signal and noise, the signal-to-noise ratio (SNR) at the receiver can vary significantly. In order to minimise these SNR fluctuation effects, this paper discusses some advanced techniques for the design of non-directed wireless infrared communication systems that can produce interesting performance improvements.
Electronic tracking for wireless infrared communications
IEEE Transactions on Wireless Communications, 2003
A high-speed wireless system ( 100 Mb/s) for indoor infrared (IR) communications via the line of sight is described and feasibility is shown in an experimental demonstrator. A diffuse link is used for connectivity, and tracked directed links are used for high-speed communications.