Broadband and low loss capability of photonics has led to an ever-increasing interest in its use for the generation, processing, control and distribution of microwave and millimeter-wave signals for applications such as broadband wireless access networks, sensor networks, radar, satellite communitarians, instrumentation and warfare systems. In this tutorial, techniques developed in the last few years in microwave photonics are reviewed with an emphasis on the systems architectures for photonic generation and processing of microwave signals, photonic true-time delay beamforming, radio-over-fiber systems, and photonic analog-to-digital conversion. Challenges in system implementation for practical applications and new areas of research in microwave photonics are also discussed.

Microwave Photonics

Microwave photonics is an area that studies the generation, processing, control and transmission of microwave signals by means of photonics. In this paper, microwave photonics techniques developed in the past few years will be reviewed, with an emphasis on system architectures for microwave applications.

http://ieeexplore.ieee.org/iel5/6305327/6320324/06320333.pdf

Microwave photonics

With the deployment of high speed train (HST) systems increasing worldwide and their popularity with travelers growing, providing broadband wireless communications (BWC) in HSTs is becoming crucial. In this paper, a tutorial is presented on recent research into BWC provision for HSTs. The basic HST BWC network architecture is described. Two potential cellular architectures, microcells and distributed antenna systems (DASs) based cells, are introduced. In particular, the DAS is discussed in conjunction with radio over fiber (RoF) technology for BWC for HSTs. The technical challenges in providing DAS-based BWC for HSTs, such as handoff and RoF are discussed and outlined.

Distributed Antenna Systems for Mobile Communications in High Speed Trains

Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.

Method and apparatus for coupling an antenna to a device

A distributed antenna system is provided that frequency shifts the output of one or more microcells to a 60 GHz or higher frequency range for transmission to a set of distributed antennas. The cellular band outputs of these microcell base station devices are used to modulate a 60 GHz (or higher) carrier wave, yielding a group of subcarriers on the 60 GHz carrier wave. This group will then be transmitted in the air via analog microwave RF unit, after which it can be repeated or radiated to the surrounding area. The repeaters amplify the signal and resend it on the air again toward the next repeater. In places where a microcell is required, the 60 GHz signal is shifted in frequency back to its original frequency (e.g., the 1.9 GHz cellular band) and radiated locally to nearby mobile devices.

Remote distributed antenna system

A distributed antenna network (DAN) is demonstrated to improve the coverage of in-building wireless services. A doubling in the number of locations with a high throughput is achieved. A detailed analysis of the performance improvement of a three-antenna DAN over a single-antenna system shows that 10-dB more power would be required from the single antenna to achieve a comparable performance. The effect of the additional delay spread generated by the DAN is also discussed, and the conditions under which it does not degrade performance are investigated.

Uplink and Downlink Coverage Improvements of 802.11g Signals Using a Distributed Antenna Network

A RF-over-fibre distributed multi-antenna network is demonstrated to improve coverage and reduce the required dynamic range of co-existing IEEE 802.11 g WLAN and 3G services by using overlapping cells, fed from a single signal source.

Demonstration of a Radio over Fibre Distributed Antenna Network for Combined In-building WLAN and 3G Coverage

This paper reports the use of semiconductor optical amplifier (SOA) based routing switches in radio-over-fiber (RoF) systems. It is shown that only little additional penalty is introduced by the switches. A proof-of-principle 10 × 10 switching unit is employed in a time-domain switched RoF network, where an SFDR of 96.5dB·Hz2/3is achieved and a 10MSymbol/s QPSK modulated signal at a carrier frequency of 2.5GHz is switched with an EVM of 1.48%. Switching times as low as 50μs are achieved, limited by the driving circuitry of the SOAs. Furthermore, it is demonstrated that the switch is scalable and can be cascaded.

Application of Semiconductor Optical Amplifiers in Scalable Switched Radio-over-Fiber Networks

A 3times3 SOA-based switch is demonstrated for routing both radio-over-fiber and digital signals simultaneously. High extinction ratio digital baseband signals are transmitted and sufficient linearity is found for high performance RF signal distribution.

Sheng Li

Papers

Uplink and Downlink Coverage Improvements of 802.11g Signals Using a Distributed Antenna Network

Demonstration of a Radio over Fibre Distributed Antenna Network for Combined In-building WLAN and 3G Coverage

Application of Semiconductor Optical Amplifiers in Scalable Switched Radio-over-Fiber Networks

A novel SOA-based crosspoint switch for mixed signal distribution