Ultrahigh-Speed Wireless LAN Prototype in the 38GHz Band

The millimeter (mm)-wave band (from 30 to 300 GHz) is the focus of considerable academic and industrial interest because it can support high-speed and large-capacity information transmission. New applications, such as ultrahigh-speed wireless local area networks (WLAN), wireless home-links, and indoor multiplex television broadcasting for indoor environments, as well as fixed wireless access, broadband mobile access, and ITS (intelligent transportation systems)-based inter-vehicle communications for outdoor environments will become available through the use of mm-wave communications. In Japan, the 38 GHz band has been made available for fixed wireless access and the 60 GHz band with a bandwidth of over 10 GHz will be made available for licensed and unlicensed use very soon[1]. The development of the mm-wave band for communications began at the Communications Research Laboratory in the early 1990s[2]. As a result of early research on the mm-wave propagation characteristics and the development of devices and equipment for mm-wave communications, several indoor high-speed WLAN prototypes were developed[2]~[7]. An ATM(asynchronous transfer mode) based WLAN prototype was developed to support multimedia transmission in 1998[4][5][6]. It is a centralized system consisting of an access point (AP) connected to a backbone network and six stations (STA) connected to multimedia terminals. The system is operating in the 60 GHz band and has an FDD (frequency division duplex) channel configuration providing high-speed transmission (51.84 Mbps) on each channel. A novel MAC (medium access control) protocol, called RSISMA (Reservation-based Slotted Idle Signal Multiple Access), was proposed and developed to support integrated multimedia transmission in the system[4][8]. The second prototype system developed in 1999, which also operates in the 60 GHz band, is an IP-based WLAN with an AP and three STAs[7][9]. Compared with the first prototype, the second one has a higher radio transmission rate (64 Mbps) on each channel. Modified RS-ISMA is used as a MAC protocol in the system. The system can support TCP (UDP)/IP-based applications and multicast