IEEE802.11af with partial subcarrier system for effective use of TV white spaces

Demand for wireless communication is increasing significantly, while the frequency availability for wireless communication is quite limited. Currently, various countries are prompting the use of TV white spaces. IEEE 802.11 WG (Working group) has started a TG (Task Group), namely IEEE 802.11af to develop the international standard for WLAN in TV white spaces. In order to increase maximum throughput, a channel aggregation mechanism is introduced in the draft standard of TGaf. In Japan, ISDB-T based area-one-segment broadcasting system (Area-one-seg) which is a digital TV broadcast service in the limited area have been permitted to do actual services in TV white spaces from April 2012. The operation of the IEEE 802.11af system shall not jeopardize the Area-one-seg system due to the common operating frequency band. If the Area-one-seg partially overlaps with the IEEE 802.11af in some frequency, the IEEE 802.11af cannot use the channel aggregation mechanism due to lack of channels. As a result, the throughput of the IEEE 802.11af deteriorates. In this paper, the physical layer of IEEE 802.11af D2.0 is introduced briefly, and a partial subcarrier system for the IEEE 802.11af is proposed to effective use of TV white spaces and increase throughput. The IEEE 802.11af systems effectively coexist with the Area-one-seg by using null subcarriers. Computer simulation shows up to 60 % throughput gain is achieved with the proposed mechanism.