The authors examine microcell radio systems that use subcarrier transmission and spectrum delivery switch (SDS) techniques to meet traffic demands for a large number of portable phones. Radio signals are transmitted over fibre between base stations (BS) and a central station (CS). Relationships between blocking probability and offered traffic are described as a parameter of SDS ports. Optical link performances, such as link gain and carrier-to-noise ratio (CNR), are presented. Moreover, it is found that using FM techniques can improve the dynamic range by 20 dB compared to conventional methods for the uplink from BS to CS. The proposed technique can also increase the number of transmittable carriers compared to conventional methods for the downlink from CS to BS. This network strategy results in more flexible transmission. >

Fiber-optic microcell radio systems with a spectrum delivery scheme

This article proposes a fiber and radio extension link (FREx Link) that offers the advantage of enhancing the flexibility of the various communication systems. In this article, two examples of applications for FREx Link, the intercell connection link (ICCL) and the fiber to the area system (FTTA), are described. Some numerical results of the system design considerations are given for each example. © 1993 John Wiley & sons, Inc.

Proposal of fiber and radio extension link for future personal communications

In this paper, synchronons code division multiple access (S/CDMA) for fiber-optic local area networks is considered. The performance of the fiber-optic S/CDMA network with negligible thermal and shot noises is interference limited. Here we derive the bit error rate of the S/CDMA system as a function of code length and number of active users, and the performance characteristics are also discussed. Furthermore, we analyze the performance of the fiber-optic S/CDMA system with an ideal optical hard-limiter, and the error probability with error control coding is also derived. In addition, the optimization between the S/CDMA and BCH codes of a constant bandwidth system is presented. The results show that by using an ideal hard-limiter in conjunction with BCH codes in this system, the influence of interference arising from other users can be greatly reduced, and the number of active users can also be increased significantly. >

Synchronous fiber-optic CDMA using hard-limiter and BCH codes

Broadband distribution networks are presented combining digital microwave radio with optics using subcarrier multiplexing (SCM) transmission. In the first implementation of a high-capacity transmission, the authors present the prospect of fiber-optic transmission of microwave 256 quadrature amplitude modulation (QAM) signals at 10-Mb/s and 50-Mb/s transmission rates. Bit error rate (BER) performance results are shown as a function of received optical power and optical modulation index. It is shown that the results of theoretical BER performance calculations are in agreement with that of preliminary experiments for two types of 256-QAM signals. Error correction coding using a BCH code is very effective in improving the system performance. Finally, the choice of the total optical modulation index for multichannel transmission is discussed. >

http://ieeexplore.ieee.org/iel2/536/4777/00188676.pdf

256-QAM subcarrier transmission for broadband distribution networks

Future communication systems will require high data rates and flexible modulation. Direct optical phase modulation of two microchip lasers by information-bearing signals allows for high-rate delivery via fiber to a basestation. At the basestation, the coherent optical signals are combined with a reference in a photodetector to produce a microwave/millimeter-wave carrier with arbitrary M-ary quadrature amplitude modulation, which can then be transmitted over a wireless channel. Rapid tuning of the microwave/millimeter-wave carrier, the modulation scheme, and the data rate is achievable through this method with no fixed oscillators at the basestation, thus providing for flexible architectures. Results show a high-quality carrier and, for 4- and 16-QAM, with data rates to 200 Mb/s. Extensions to higher data rates are discussed.

Coherent optical vector modulation for fiber radio using electrooptic microchip lasers

Fiber-optic transmission of 256 quadrature amplitude modulation (QAM) signals at both 10 Mb/s and 50 Mb/s transmission rates are presented. Theoretical and preliminary experimental bit error rate (BER) performance results are described for two types of 256-QAM signals. Application of error correction coding using a BCH code is very effective in optical analog intensity modulation. It is feasible to use 256-QAM signals as subcarriers in fiber distribution networks. >

256-QAM subcarrier transmission using coding and optical intensity modulation in distribution networks

As a low-loss, wide-bandwidth transmission medium that is beamed through the atmosphere, digital microwave radio has been widely used for long-haul, large capacity links by many countries around the globe. Considering the growing demand for increased diversification in networks, however, more attention should be focused on applying DMR to those areas that best exploit the medium's original strengths-- that is, easy and flexible network construction. Today, the trend in user needs is evolving in contrary directions: toward more personalized service on the one hand and toward global-scale reach on the other. In this paper we propose what we call a Digital Microwave Radio Highway as a practical approach to reconciling these conflicting tendencies. As we describe the various enabling technologies involved, this gives us an opportunity to survey the R&D on digital microwave radio (DMR) systems that is being conducted in Japan today.

Kenji Kohiyama

Papers

256-QAM subcarrier transmission using coding and optical intensity modulation in distribution networks

Recent R &D on Digital Microwave Radio Reray Systems