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This paper introduces the dynamic spot diffusing (DSD) configuration for high-speed indoor wireless optical communications. In this configuration, data are modulated onto a moving spot which is translated over the ceiling. A multi-element imaging receiver is pointed upward and acquires data whenever the transmitter spot is in its field-of-view (FOV). We develop expressions for the channel capacity of such DSD links and discuss design techniques to maximize these information theoretic bounds. Rather than tracking the transmitter spot, we apply rateless erasure correcting codes to approach the capacity of the simulated DSD links. This technique is demonstrated to have better flexibility, greater multipath immunity, higher data rates and simpler transmitters than previously defined multi-spot and diffuse architectures. In a 6 x 6 x 3 m room, simulated data rates vary between 7 Mbps to 25 Mbps at different positions using a single 100 Mbps transmitter and between 35 Mbps to 84 Mbps using 6 spots and the designed erasure correction code. Using power efficient modulation and power gain due to the spot motion of the DSD system, proportionally higher rates are estimated when faster 1 Gbps and 10 Gbps transmitters are employed. Index Terms--Wireless infrared channel, indoor diffuse infrared communication, optical intensity modulation, spot diffusing architecture.

In optical burst switched (OBS) networks, the queueing delay in ingress edge node is an important performance measure. In this paper, we propose a deterministic delay model and derive the upper bound of the burst queueing delay in an edge node. On this basis, the edge-to-edge delay guarantee framework for premium services is further outlined. Index Terms--Optical burst switching, deterministic QoS, delay analysis.

A modified dilated Benes network composed of directional couplers is proposed. This structure is introduced to improve the signal-to-noise ratio (SNR) characteristics of dilated Benes networks. A new estimation of the SNR for dilated Benes networks is derived, and it is shown that this SNR is much worse than that previously known. The SNR for modified dilated Benes networks is estimated and compared to dilated Benes and other network architectures. Some other properties including the number of switching elements required, number of crossovers, and system attenuation are also derived and analyzed. Most of the characteristics are shown to be similar to dilated Benes networks and better than those of other well-known networks fabricated in Ti: LiNb[O.sub.3]. Index Terms - Communications switching, directional couplers, photonic switching networks.

In this paper, we study the use of multiuser detection and blind detection techniques to improve the performance of optical code-division multiple-access (OCDMA) systems. First, a new multiuser receiver known as the interference suppression receiver is proposed. Second, we study the use of blind detection by proposing a blind receiver for OCDMA systems. While previous studies on multiuser detection are limited to systems with p-i-n detectors, avalanche photodiode detectors are also included here. Index Terms - Avalanche photodiode detectors, code division multiple access, multiple-access interference, multiuser detection, optical communications.

In this paper, we examine the use of differential pulse-position modulation (DPPM) for optical communication systems using intensity modulation with direct detection in the presence of additive white Gaussian noise. We present expressions for the error probability and power spectral density of DPPM. We show that for a given bandwidth, DPPM requires significantly less average power than pulse-position modulation (PPM). We also examine the performance of DPPM in the presence of multipath intersymbol interference (ISI). We find that the ISI penalties incurred by PPM and DPPM exhibit very similar dependencies upon the channel rms delay spread. We discuss the use of chip-rate and multichip-rate equalization to combat ISI. Finally, we describe potential problems caused by the nonuniform bit-rate characteristic of DPPM, and we propose several solutions. Index Terms - Differential pulse-position modulation, intensity modulation, wireless optical communication.