Prof. Beatriz Ortega Tamarit
Instituto de Telecomunicaciones y Aplicaciones Multimedia (ITEAM),
Universitat Politècnica de València, Spain

MICROWAVE PHOTONICS SIGNAL GENERATION FOR 5G NETWORKS

Enabling technologies for 5G networks include the use of millimeter waves (MMW) between 30-100 GHz to overcome spectral congestion and increase bandwidth; small cells to allow frequency reuse with a large number of base stations and also massive multiple-input multiple-output (MIMO) full-duplex transmission and beamforming techniques.

A major challenge in the 5G mobile radio access network is the efficient integration of a large number of small cells into the existing network. A fully centralized Cloud Radio Access Network (C-RAN) approach shifts the signal processing from the remote radio heads (RRHs) to a base band unit (BBU) in a central unit and therefore leads RRHs as based on opto-electrical converters, electrical amplifiers and antennas. In a C-RAN architecture for 5G networks deployment, the data will be carried by a MMW signal and delivered from a central station (CS) to an optical distribution network (ODN). Transportation of radio signals over large distances makes advantage of the low optical fibre losses but, moreover, the inclusion of free-space optics (FSO) links is a promising solution to meet future capacity and coverage challenges while reducing the infrastructure costs, especially in rural or remote areas, as well as crowded urban segments.

One of the most challenging stages in these systems is the generation of the MMW signals due to the limited frequency response of electronic components. During the last two decades, a large variety of microwave photonic (MWP) solutions for MMW signal generation have been proposed in the literature including phase control, sideband injection locking, frequency multiplication or nonlinear mechanisms, amongst others. However, the role of MWP signal generation in future 5G networks deployment will be properly defined according to the requirements of future mobile networks and also considering other practical issues, such as cost and complexity of these systems.

---

   

 
Abstract:
After a surge of research on key technologies of VLC systems, considerable bitrate have been achieved through various schemes, such as DMT, OFDM, MIMO, DPD... To promote the VLC technologies, attention should be paid also to its practical application scenarios, such as broadband access, optical networking and indoor positioning.
This talk will introduce the recent work in the State Key Laboratory of Information Photonics and Optical Communications. We designed and implemented a VLC networking system, with one VLC access point (VLC-AP) and several VLC user equipment models (VLC-UEs), operating through the self-developed protocol which maintains a simple mechanism of time division multiple address (TDMA). The user terminals (such as PADs and laptops) are connected to VLC-UEs via Ethernet interface and they can access the Internet through the VLC-AP and also they can perform peer-to-peer communication. Various files (such as txt, mp3, mp4 and so on), are able to be transmitted through real-time uplinks and downlinks in this network, including real-time voice and real-time video. The interrupted services are restored automatically. However, dynamic TDMA mechanism is to be implemented in the future and the flexibility at VLC-UEs is to be improved to support seamless handover from one VLC-AP to another.