KT has installed 40% of world's 35,000 hotspots in Korea The nation's telecom companies have been continuing their pioneering role in applying advanced mobile technologies to practical use as they did with code division multiple access. (CDMA) Owing to the strenuous efforts led by the nation's foremost wireless carrier SK Telecom, the world's 10th largest economy has become revitalized with the growth of the mobile telephony services and cell phone production. With CDMA success under its belt, the country is once again at the forefront of deploying next-generation techniques that evolved from CDMA such as wideband CDMA (W-CDMA) and orthogonal frequency division multiplexing (OFDM). Customers now use wireless local area network (LAN) services at restaurants in Seoul. The nation already launched WCDMA in late 2003 and OFDM platform is also in brisk use here in the form of wireless local area network (WLAN), spearheaded by primary fixed-line telecom entity KT. KT currently maintains roughly 14,000 hot spots, or WLAN available areas, up to 40 percent of the world's total tally of 35,000. There is a flurry of multiplexing technologies, essential in order to enable millions of wireless phone calls with relatively narrow radio spectrum bandwidth. Because the spectrum is a very limited resource, it is impossible for the government to allocate a wide range of it for wireless telephony services. To address challenges of processing numerous calls with a narrow frequency band came multiplexing techniques of combining a number of signals. Up until now, three major multiplexing methods have been developed -frequency division multiple access (FDMA), time division multiple access (TDMA) and CDMA. FDMA is the oldest and still most important way of enhancing the efficiency of radio frequencies by dividing them into segments so that many users can share them concurrently. Based on FDMA came two more advanced versions of TDMA and CDMA. After dividing given frequency into several lanes, TDMA split it again by dividing it into different time slots. By comparison, CDMA does not divide up the channel by time but instead encodes with data with a certain code that can be received by only a compatible receiver, or cell phone. FDMA is the most fundamental technology and all of the latest formats like TDMA and CDMA also hinge on it. TDMA had emerged as a mainstream in the 1990s but CDMA stole the show in the 2000s. Next-generation solutions like W-CDMA and OFDM are evolution of CDMA of which viability was shaky just a decade ago but Korea fended off the concerns by successfully commercializing the formula. The world tilted into global standards for communications (GSM), which is based on TDMA in the mid 1990s but Korea selected CDMA as a single national standard in 1995. Spearheaded by SK Telecom, Korea kick-started every version of CDMA for the first time in the world even faster than the United States, the hometown of the then-underdog technology. SK Telecom stunned the world by commercially launching CDMA services in 1996 and it continued to set the trend by embarking on advanced versions of CDMA2000 1x in 2000 and EV-DO (evolution data optimized) two years later. In addition, SK Telecom jump-started W-CDMA service late 2003, the thirdgeneration (3G) form of CDMA families, along with the nation's runner-up player KTF. In adopting OFDM, which are regarded as the mainstream format of the future, Korea is also playing a major role. The country applied OFDM into two sectors of WLAN and WiBro, which provide folks outdoor connection to the highspeed, always-on Internet. KT launched OFDM-based WLAN early this month, which boasts a maximum speed of 54 megabits per second (Mbps), or about 20 times faster than current fixed-line hook-up. The services are available at universities, hotel lobbies and airport lounges, which are called "hot spots."