Basic introduction
The emergence of CDMA technology stems from the human demand for higher quality wireless communication. During the Second World War, CDMA technology was studied and developed for the needs of war. Its original intention is to prevent the enemy from interfering with their own communications. It was widely used in military anti-jamming communication during the war, and was later updated as a commercial cellular telecommunication technology by Qualcomm. 1995, after the first commercial CDMA system (called IS-95A) was operated in Qualcomm, the theoretical advantages of CDMA technology were tested in practice, thus it was rapidly popularized and applied in North America, South America and Asia. Many countries and regions in the world, including Chinese mainland, Hongkong, China, South Korea, Japan and the United States, have established commercial CDMA networks. In the United States and Japan, CDMA has become the main mobile communication technology in China. In the United States, 7 out of 65,438+00 mobile communication operators choose CDMA. By April 2006, 60% of the Korean population had become CDMA users. CDMA technology played an important role in the 27th Olympic Games held in Australia.
China Unicom officially opened CDMA network on June 8th, 2002 and put it into commercial use. After June 65, 438 +4381October 65 +0, 438, it was transferred to China Telecom, with the mobile phone numbers of 65,438+033,65,438+089 and the new number of 65,438+080. Actress Hedy Lamarr and her composer husband defined the concept of music as early as 1942. The patent puts forward an important concept "spread spectrum technology", which has brought incredible changes to our world since then.
In 1950s, Sylvania Company in New York (where Zhang Zhongmou, the boss of TSMC, got his first job in the United States) began to do related research and development based on Heidi and George's patents. Later, in the 1960s, related spread spectrum technology appeared, and the US military began to use spread spectrum technology in military communication systems. After the end of the Cold War in 1980s, the US military deregulated spread spectrum technology and allowed it to be commercialized. Then in 1985, Qualcomm was established in California, and based on spread spectrum technology, CDMA Ji (code division multiple access) system was developed.
The emergence of CDMA technology stems from the human demand for higher quality wireless communication. During World War II, CDMA technology was developed for the needs of war. Its original intention is to prevent the enemy from interfering with their own communications.
CDMA wireless network card
During this period, it was widely used in military anti-jamming communication, and was later updated by Qualcomm to become a commercial cellular telecommunications technology. 1995, after the first commercial CDMA system was put into operation, many theoretical advantages of CDMA technology were tested in practice, thus it was rapidly popularized and applied in North America, South America and Asia. Many countries and regions in the world, including China, Hongkong, South Korea, Japan and the United States, have established commercial CDMA networks. In the United States and Japan, CDMA has become the main mobile communication technology in China. In the United States, 7 out of 65,438+00 mobile communication operators choose CDMA. 60% of South Korea's population has become CDMA users. CDMA technology played an important role in the 28th Olympic Games held in Australia. The standardization of CDMA technology has gone through several stages. IS-95 is the first released standard among cdmaONE series standards, and the first CDMA standard that is really widely used in the world is IS-95A, which supports 8K coded voice services. Subsequently, TSB74 standard of 13K speech encoder came out respectively, which supported STD-008 standard of CDMA PCS system of 1.9GHz, and the voice service quality of 13K coding was very close to that of wired telephone. With the increasing demand for data services in mobile communication, Qualcomm announced in February 1998 that the IS-95B standard will be used in CDMA infrastructure platform. IS-95B can provide CDMA system performance, increase the data flow of users' mobile communication devices, and provide support for 64kbps data services. Since then, cdma2000 has become the transition standard of narrowband cdma system to the third generation system. At the initial stage of standard research, cdma2000 put forward the development strategies of 1X and 3X, but subsequent research shows that the enhancement technologies of 1X and 1X represent the future development direction.
The standardization of CDMA technology promotes its worldwide application. In the United States, South Korea, Japan and other countries, CDMA technology has been widely used. In some European countries, some operators have also built CDMA networks. According to the statistics of CDG (World CDMA Development Group), the number of CDMA users at the end of 1996 was only 1 10,000; By March of 1998, it had rapidly increased to100000; By September, 1999, the number of users had exceeded 40 million. At the beginning of 2000, the total number of CDMA mobile phone users in the world exceeded 50 million, and the number of users increased by 1 18% within one year. CDG said that Asia has become the main driving force for the growth of CDMA market, and the number of CDMA users in Asia has increased by 88% compared with a year ago, reaching 28 million. The growth rate of the United States is as high as 143%, reaching16.5 million, but the absolute number of users is lower than that of Asia. In the Asia-Pacific region, China, Hongkong, Japan, South Korea, Australia, Thailand, India, the Philippines, New Zealand, Bangladesh and other countries and regions have established CDMA commercial networks with more than 26,543,800 users. The third growth rate is in Central America and South America, with 5 million CDMA users. CDG also said that Chinese mainland is the region with the greatest growth potential in the global CDMA market in the future, and it is estimated that the number of users in Chinese mainland market will reach 40 million in 2003. [ 1]
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