Radio-Over-MMF Techniques—Part II: Microwave to Millimeter-Wave Systems

Microwave to mm-wave radio carriers are commonly employed for creating high-capacity picocell wireless networks. Advanced radio-over-fiber (RoF) techniques can efficiently generate and transport such carriers, and deliver them to simplified antenna stations. As in in-building networks multimode fiber is predominantly used, adequate radio-over-multimode fiber (RoMMF) techniques are required to overcome the modal dispersion in multimode fiber links. The optical frequency multiplying technique is introduced; it is relatively simple to implement, yet it is shown to be robust against the modal dispersion, and it is able to generate very pure microwave carriers while requiring only moderate speed electronics. Thus, it can convey high data rates in comprehensive modulation formats on multiple-GHz carriers in MMF networks. It offers simultaneous operation at multiple radio standards, and capabilities for dynamic adaptation of the radio link parameters such as carrier frequency, transmit power, and other antenna site functions by means of an embedded control channel. Moreover, in combination with optical routing it enables dynamically adjustable network configurations for flexible wireless service delivery.

I. Introduction

After the installation of fiber as deep as possible into the access network, i.e., up to the doorstep of the home in an FTTH topology, the next challenge is to extend its broadband capacity into the residential home [1]. More in general, this also concerns other buildings such as hospitals, office buildings, conference centers, airport departure lounges, etc. In those networks, the demand for broadband services for wirebound as well as wireless devices is rapidly growing, fueled by broadband internet, fast peer-to-peer file transfer, high definition video, on-line multiparty gaming, etc. Gbit/s wirebound capacity is needed to feed fixed terminals, such as desktop PC-s, (HD)TV sets, scanners, printers, local storage servers, etc. In addition, a large wireless capacity is needed. High carrier frequencies of 10 GHz and above are required, and many radio picocells. For example, the IEEE 802.16-2004 standard specifies frequencies between 10 and 66 GHz for Fixed Wireless Access, and can deliver up to 100 Mbit/s. The IEEE 802.15.3c standard can provide up to 3 Gbit/s over short ranges in Wireless Personal Area Networks, with carrier frequencies between 57 and 64 GHz.