Geo-location White Space Spectrum Databases: Models and Design of South Africa’s First Dynamic Spectrum Access Coexistence Manager

Abstract

Geo-location white space spectrum databases (GL-WSDBs) are currently the preferred technique for enabling spectrum sharing between primary users and secondary users or white space devices (WSDs) in the very-high frequency (VHF) and ultra-high frequency (UHF) bands. This is true because technologies for making low-cost WSDs capable of autonomous sensing and detection of available white space (WS) spectrum are not yet feasible. This paper reviews the necessary enabling technical conditions to allow coexistence of primary and secondary systems in the VHF and UHF spectrum through a GL-WSDB approach. The practical implementation of South Africa's first GL-WSDB was performed. Results of WS channels available from five cities in South Africa calculated from the implemented GL-WSDB was compared with a commercially available GL-WSDB and was found to be 68% similar. Additionally, results from the implemented GL-WSDB were compared with measurements obtained from field spectrum scanning campaigns at two different locations in Cape Town, South Africa, and was found to be 64% similar.

Case Notes: Considering Possible Regulatory Approaches to Television White Spaces (TVWS): A View from South Africa

“…In addition, the GL-WSDB implemented for this trial has the potential to record the characteristics of the WSDs, and prevent interference between them. (Mfupe, Mekuria & Mzyece, 2014) During the first trial, the modulation used was improved up to 16QAM. The current state of the art is 64QAM.…”

“…When spectrum is shared, then the users are obliged to coordinate and ensure that they cause no interference to each other (TENET, 2013;Pahl 2007). Dynamic spectrum management (DSM) is the emerging regulatory model that arises out of TVWS research (Mfupe, Mekuria & Mzyece, 2014), addressed further below.…”

“…In either case, a new regime, dynamic spectrum management, has an important role to play. Dynamic spectrum management (DSM) entails carrying out calculations, as often as on a real-time basis, to determine if a candidate use can be accommodated without causing interference to other users (Mfupe, Mekuria & Mzyece, 2014).…”

“…This is to ensure that an accurate radio frequency propagation pattern may be developed for each WSD, in order to calculate whether the WSDs will interfere with each other, or with television viewers. South Africa uses several radio propagation algorithms, with GIS and clutter data, also called a geo-location database (Mfupe et al, 2014). The position and characteristics of every licensed user of the spectrum in question must be accurately recorded in the database, and every white space device authorised to operate -whether licensed or licence-exempt -must similarly be recorded.…”