실내 무선환경에서의 UWB 채널모델링 연구

Abstract

A baseband multiple access method has limitation for multimedia high speed data transmission. Ultra broadband based upon multiple access method like OFDM and CDMA has attracted by the need for recently high speed data transmission using wireless channel. Recently UWB technology has widely adopted by telecommunication and electronic equipment, because it has been researched by America and various countries. Federal Communications Commission (FCC) restrictively allows UWB frequency between 3.1GHz to 10.6GHz using high speed telecommunication. In this way UWB system that has operated wide frequency band can effect to the existing wireless frequency. UWB system limits radiant power (Power spectrum density) under -41.25dBm/MHz for reducing coherent existing RF communication system. Because UWB system share frequency with traditional telecommunication system, coexistence problem between UWB system and existing IEEE 802 telecommunication system, especially detection and avoid between another baseband RF communication systems under complicated RF environment has studied by various countries and it has been done or studying about technical standards It is certainly different technique compared with traditional communication technique and it uses low power (1mW below) broadband. UWB can use limited area in these days, however it will be used wide area in the future. UWB will be faster, more cost effective and support more user than recent wireless LAN system. UWB system that use extremely short RF pulse(nsec below), instantly occur wide broadband signal in time domain. This system is defined that frequency band is more than 20% center frequency or bandwidth is more than 500MHz. It can effect every frequency because it uses wide frequency band limited. Because of upper problems, UWB system limits radiant power (Power spectrum density) under -41.25dBm/MHz not to interfere with existing RF communication system. But because UWB system share frequency with traditional telecommunication system, it is considered many factor like coexistence problem between UWB system and existing IEEE 802 telecommunication system, interference between another baseband RF communication systems under complicated RF environment, endurance under multi channel, and so on. Therefore, for mentioned above, it is very important to investigate and analysis what problems happen to use UWB in existing communication environment and it is also very important to define technical standards about interference