Keigo Hasegawa

Field experiment of long-distance broadband communications in TV white space using IEEE 802.22 and IEEE 802.11af

A field experiment of TV White Space (TVWS) communications was conducted using developed systems following IEEE 802.22 and IEEE 802.11af standards and succeeded to have the world first throughput, distance, and application testing. The IEEE 802.22 system achieved throughput of 4.5 Mbps for uplink and 5.2 Mbps for downlink over 12.7 km. Also, feasibility of applications such as web browsing, video streaming and video talk was confirmed in multi-hop network where the IEEE 802.22 system was a backbone link and IEEE 802.11af was access area expansion. Furthermore, aggregating bandwidth of two discontinuous TV channels, throughput of 15.5 Mbps for downlink and 9.0 Mbps for uplink was achieved over 6.3 km.

IEEE 802.22-based WRAN system for disaster-resistant network systems

When the great disaster strikes, it is most important for victims to receive and transmit appropriate information in order to evacuate immediately and to request for assistance and rescue. The Great East Japan Earthquake teaches us the importance of information communication technology (ICT) using wireless communication technology, e.g., television (TV), radio, the community wireless system for disaster, and mobile phone. However, after the disaster occurrence, particularly, mobile phones were left unusable for a long time due to network congestion, physical damage to base stations, and out-of-fuel of standby power systems. To combat these problems, the ICT services require more robustness, availability, flexibility, and redundancy. In this paper, we discuss the competence of IEEE standard 802.22-based wireless regional area network (WRAN) using television white space (TVWS) which can provide wide service area and utilize geographically or temporally unoccupied resource of TV frequency bands, although the frequency bands are allocated by regulatory domain. Furthermore, we introduce and evaluate a developed prototype of the WRAN equipment. The prototype provides point-to-multipoint service and throughput up to 12.2 Mbps in downstream (DS) and 9.5 Mbps in upstream (US).

A physical layer implementation of IEEE 802.22 prototype

In this paper, we present a recently developed physical layer implementation of IEEE 802.22 prototype. The prototype includes the following components: a channel (CH) unit, a Medium Access Control Layer (MAC) Control unit, a Global Positioning System (GPS) unit and a Radio Frequency (RF) control unit. The prototype is developed in a flexible and scalable platform to enable future enhancement for higher data rate application. In order to achieve higher data rate, the prototype is designed to accommodate multiple channel units for multiple channel access capability. A channel unit consists of a MAC Layer unit, a Physical Layer (PHY) unit and a Transceiver (TRX) unit. In this paper, we will concentrate our discussion on the physical layer implementation of IEEE 802.22 prototype and show the Bit Error Rate (BER) performances of the implemented physical layer of IEEE 802.22 prototype.