This PDF file contains the front matter associated with SPIE Proceedings Volume 7620, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Mobile networks and services have gone further than voice-only communication services and are rapidly developing towards data-centric services. Emerging mobile data services are expected to see the same explosive growth in demand that Internet and wireless voice services have seen in recent years. To support such a rapid increase in traffic, active users, and advanced multimedia services implied by this growth rate along with the diverse quality of service (QoS) and rate requirements set by these services, mobile operator need to rapidly transition to a simple and cost-effective, flat, all IP-network. This has accelerated the development and deployment of new wireless broadband access technologies including fourth-generation (4G) mobile WiMAX and cellular Long-Term Evolution (LTE). Mobile WiMAX and LTE are two different (but not necessarily competing) technologies that will eventually be used to achieve data speeds of up to 100 Mbps. Speeds that are fast enough to potentially replace wired broadband connections with wireless. This paper introduces both of these next generation technologies and then compares them in the end.

The investigation of next-generation optical access network (NG-OAN) systems as well as the corresponding standardization activities has been steadily progressing. In the near future, whenever such a NG-OAN system is deployed to meet the bandwidth demands, the smooth migration from the existing system is indispensable because current PON systems such as 1G-EPON/G-PON have been massively deployed all over the world. NGA systems should be deployed so as not to interrupt existing system operation or degrade in-service user availability. I introduce recent technical topics related to co-existence with 1G/10G-EPON as an example. In particular, a 1G/10G dual-rate dynamic bandwidth allocation (DBA) technique and a 1G/10G dual-rate burst-mode transceiver are key technologies enabling 1G- and 10Gdata to be handled simultaneously. Furthermore, from the CAPEX/OPEX reduction viewpoint, longer lifetime system is preferable. NGA systems will, therefore, be more flexible to meet later bandwidth demands, wide coverage requirement, and energy-efficient operation. WDM technology is an attractive approach to meeting these goals.

Passive Optical Network (PON) and Mobile Worldwide Interoperability for Microwave Access (WiMAX) are two emerging broadband technologies for the next-generation (NG) access networks. Integration of PON and Mobile WiMAX might be an efficient solution to broadband network access that can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. By leveraging the advantages of both of these access technologies combined on an integrated architecture platform, NG converged-access solutions can meet the demand for mobility, bandwidth, reliability, security, and flexibility. By combining the practically unlimited capacity of optical fiber networks with the ubiquity and mobility of wireless networks, NG Fiber-Wireless (FiWi) networks will enable the support of a wide range of emerging and unforeseen fixed-mobile applications and services independent of the access infrastructure. PON and 4G Mobile WiMAX integrated architecture enables differentiated bandwidth allocation to end users that can provide more network capacity at reduced operational cost as compared to other existing technologies.

Fiber architecture solutions for providing wireless network coverage by radio-over fiber feeding in buildings are discussed. The focus is on very high wireless data rate applications (>>100 Mb/s) with short wireless distances (typ. <10m). Up to 20 Gb/s signal transmission at 60 GHz is demonstrated.

We demonstrate the superior RF spectrum characteristics of an ultra-linear modulator. This modulator exhibits excellent linearity (Spurious Free Dynamic Range, SFDR ~ 133 dB at 1Hz bandwidth), wider linearization bandwidth (an order of magnitude wider), and flatter RF modulation frequency dependence characteristics (linearized 3dB bandwidth ~ 20% of central RF frequency) when compared with Resonator- Assisted Mach Zehnder (RAMZ) modulators. The modulator is based on a traveling-wave electrode design, in which a phase modulator (PM) is on the upper arm of a Mach Zehnder (MZ) interferometer and a ring resonator (RR) is located on the lower arm. This modulator design is also shown to have flexible control of the power split ratio of an RF input to both the PM and the RR, in addition to the RF phase bias between the RR and PM - which enables better manufacturing tolerance.

In this work we report the photonic generation of microwave signals for distributing point to point analog TV signals by using microstrip antennas. The experimental setup is based on optical heterodyne technique where two optical waves at different wavelengths are mixed and applied to a photodetector. The microwave signal obtained by using this technique is used in a wireless communication system for transmitting and receiving analog TV signals.

In typical radio-over-fiber (RoF) systems, sub-carrier multiplexing is achieved by using directly modulated laser diode (LD). However, the conventional LD for optical communication system has non-linear characteristics such as, 3rd order intermodulation distortion (IMD3), which degrade overall analog RoF system performance. In addition, when the multi-channel input signals are modulated directly, 5th order intermodulation distortion (IMD5) signals act as a noise on overall systems. In this paper, we experimentally demonstrate an opto-electrical predistortion optical transmitter to enhance IMD3 & IMD5 for radio-over-fiber systems. To reduce the 3rd and 5th order intermodulation (IM3 & IM5), master laser diode (MLD) and slave laser diode (SLD) with similar performance are used, and the matching circuits of two LDs are designed with equal properties. The amplitude and phase balances as well as bias current of two LDs are carefully considered for the enhancements. The experimental results show that reductions of about 30 dB in the IM3 and about 12 dB in the IM5 are achieved at 2.2 GHz.

The generation, distribution and processing of microwave signals in the optical domain is a topic of research due to many advantages such as low loss, light weight, broadband width, and immunity to electromagnetic interference. In this sense, a novel all-optical microwave photonic filter scheme is proposed and experimentally demonstrated in the frequency range of 0.01-15.0 GHz. A microwave signal generated by optical mixing drives the microwave photonic filter. Basically, photonic filter is composed by a multimode laser diode, an integrated Mach- Zehnder intensity modulator, and 28.3-Km of single-mode standard fiber. Frequency response of the microwave photonic filter depends of the emission spectral characteristics of the multimode laser diode, the physical length of the single-mode standard fiber, and the chromatic dispersion factor associated to this type of fiber. Frequency response of the photonic filter is composed of a low-pass band centered at zero frequency, and several band-pass lobes located periodically on the microwave frequency range. Experimental results are compared by means of numerical simulations in Matlab exhibiting a small deviation in the frequency range of 0.01-5.0 GHz. However, this deviation is more evident when higher frequencies are reached. In this paper, we evaluate the causes of this deviation in the range of 5.0-15.0 GHz analyzing the parameters involved in the frequency response. This analysis permits to improve the performance of the photonic microwave filter to higher frequencies.

This paper reviews recent research activities on the applications and technical issues of WDM-PON. First, we describe two candidate applications of WDM-PON: one is a long-reach WDM-PON based on wavelength routing for metro/access integration, and the other is a short-reach WDM-PON for co-existence with current PON systems. We identify that the realization of colorless optical network units (ONUs) is an important technical issue for both applications, and an effective protection function is another important issue, especially for the long-reach WDM-PON. We introduce several 'colorless-ONU' approaches as well as introduce our recent research results to resolve the issues raised by some colorless-ONU approaches. In the second half of this paper, we describe two application: one is the wide-area optical/wireless hybrid access network based on long-reach WDM-PON with loop-back type colorless ONUs, and the other is the optical and wireless access based on short-reach WDM-PON coexisting with a current PON infrastructure with tunable-type colorless ONUs.

In this research paper we propose a novel Passive Optical Network (PON) based Mobile Worldwide Interoperability for Microwave Access (WiMAX) access network architecture to provide high capacity and performance multimedia services to mobile WiMAX users. Passive Optical Networks (PON) networks do not require powered equipment; hence they cost lower and need less network management. WiMAX technology emerges as a viable candidate for the last mile solution. In the conventional WiMAX access networks, the base stations and Multiple Input Multiple Output (MIMO) antennas are connected by point to point lines. Ideally in theory, the Maximum WiMAX bandwidth is assumed to be 70 Mbit/s over 31 miles. In reality, WiMAX can only provide one or the other as when operating over maximum range, bit error rate increases and therefore it is required to use lower bit rate. Lowering the range allows a device to operate at higher bit rates. Our focus in this research paper is to increase both range and bit rate by utilizing distributed cluster of MIMO antennas connected to WiMAX base stations with PON based topologies. A novel quality of service (QoS) algorithm is also proposed to provide admission control and scheduling to serve classified traffic. The proposed architecture presents flexible and scalable system design with different performance requirements and complexity.

The main objective of the presented research is to characterize an indoor wireless optical communication channel. Until recently, there have not been any comprehensive published measurements results presenting characteristics of this channel for high data rates, e. g. 1Gbit/s. To this end, a measurement setup is implemented, with a high-power laser diode acting as the optical transmitter and an avalanche photodiode acting as the receiver. Using a network analyzer, the laser is modulated by CW frequencies up to 1 GHz, which is the bandwidth of the receiver, as limited by the intrinsic capacitance and the response-time of the avalanche photodiode. A single collimated optical spot with a small elliptical shape on the ceiling is tested. The impacts of receiver orientation and configuration on the channel frequency response are investigated. These measurements will enable us to explore the possibility of higher data transmission rates, potentially beyond 1 Gbps, on indoor optical wireless channels. These channels can be a viable alternative to inherently insecure and interference-prone RF wireless channels, and therefore, could be the basis of next-generation high data rate wireless local area networks.

Free Space Optical (FSO) communications is the only practical candidate for realizing universal network coverage between ground and airborne nodes, satellites, and even moon and other nearby planets. When atmosphere (be it the earth or Mars) is a part of the optical channel, attributes of scattering and turbulence bring about amplitude attenuation, and scintillation, as well as beam wander and phase aberrations at the receiving aperture. Phase screens are usually used in order to simulate the atmospheric fading channel and phase fluctuations. In this paper, different methods of generating phase screens are compared based on their accuracy and computational complexity, as in most computer simulations, a large ensemble of phase screens are required for averaging purposes. To combat the focal plane intensity fading, caused by amplitude and phase variations in the received wave-front, it is possible to replace the Single Input-Single Output (SISO) communications system with its Multiple Input Multiple Output (MIMO) equivalent, which has the same total transmit power and receiving aperture area. Another alternative is to equip the receiver with a state of the art Adaptive Optics (AO) correction system. Using average Bit Error Rate (BER), as a performance metric, effectiveness of these two approaches are compared and it is shown that while a MIMO configuration outperforms a basic AO system capable of only tilt corrections, an ideal AO system, which is able to remove higher orders of Zernike modes can asymptotically perform as well as an equivalent MIMO configuration.

This paper presents empirical probability density functions (p.d.fs) of variance and fluctuation speed of scintillation, through analyzing a number of experimental data measured in Japan by a statistical model. The model enables us to treat scintillation speed by one parameter of cut-off frequency in the power spectral density (PDS). By using the model and based on the two p.d.fs, we also present simulation results on the level crossing rate (LCR) and average fade duration (AFD). Combined the two results, an outage probabilities corresponding to a threshold optical intensity can be derived.