Heidi Rama is not only the mother of WIFI, but also proposed that spread spectrum technology evolved into 3G technology.

Hedy lamarr was born in 19 14 and died in 2000. She is Austrian. She is not only a film actress but also an inventor.

193 1, her first electric shock. 1933, she starred in a love movie, 1937 entered Hollywood, 1939 actually participated in 25 works. 194 1 year, she invented "frequency hopping technology", which laid the foundation for CDMA, Wi-Fi and other technologies.

She is not only the mother of WIFI, but also the founder of 3G technology.

In 1940, hedy lamarr put forward the technical concept of spectrum, that is, spread spectrum technology. This technical theory eventually evolved into 3G technology. Spread spectrum is to spread the spectrum of transmission signal to a wider bandwidth than the original bandwidth for wireless communication.

So, what are the characteristics of spread spectrum technology?

The representative ways of spread spectrum are direct sequence spread spectrum and frequency hopping.

Spread spectrum began to be used in military and intelligence systems, which spread the signal to a wider spectrum and is not easy to be interfered and intercepted. Advantages are the following four aspects. Not affected by background noise and interference. It has a good resistance to artificial intentional interference. Good privacy and low possibility of interception. Reduce electromagnetic interference.

Hedy lamarr's research on this technology lost its military value after World War II, so it was sealed up. Many countries began to study it in the 1960s, but the results were minimal. Until 1985, Qualcomm developed CDMA technology, which directly led to the birth of 3G. CDMA is the basic principle of 3G, and spread spectrum technology is the basis of CDMA.

The third generation mobile communication technology is referred to as 3G for short, which is relative to the first and second generation mobile communication technologies.

The first generation of mobile communication technology is analog mobile communication technology, which is limited to voice transmission, adopts cellular structure, and the frequency band can be reused to realize large area coverage and uninterrupted communication under mobile conditions.

The second generation mobile communication system provides voice services and low-speed data services, and the core network is still based on circuit switching.

There is a 2.5-generation mobile communication system between the second generation and the third generation.

The third generation mobile communication system has many functions, such as global mobile, integrated service, data transmission cellular, cordless, paging, trunking and so on. 3G services are faster, smarter, more stable and more diversified.

It is worth mentioning that in 200 1 year, Huawei's financial growth stopped. Two years later, Ren almost sold Huawei. This test faced by Huawei was caused by the rapid development of PHS technology in China at that time. This technology is regarded as backward by international telecom giants. Huawei abandoned PHS technology and focused on 3G technology research and development with future prospects, investing billions of dollars. However, are billions of dollars profitable? At that time, it was unknown. It was not until the 3G license was issued in 2008 that there was hope of profit. Of course, today's Huawei has passed the fourth-generation mobile communication technology, entered the fifth-generation mobile communication technology, and began to plan the sixth-generation mobile communication technology.