# 6G Mobile Networks: Key Technologies, Directions, and Advances
## 3 6G Market Overview and Current Status
### Developmental Progression from 1G to 6G  
First generation (1G): 1G wireless mobile communication emerged in the late 1970s to early 1980s. It utilized analog technologies and the Advanced Mobile Phone System (AMPS) for voice services. Operating in the 824-894 MHz frequency range, it employed FDMA technology with 30 kHz channel capacity, achieving a maximum speed of 2.4 kbps. In 1988, AMPS expanded its capacity by 10 MHz through spectrum broadening. The United States introduced 1G AMPS in 1982 [22]. Second Generation (2G): 2G wireless mobile communication introduced in the early 1990s, marked a shift to digital technologies. It brought improvements over 1G by enabling both voice and basic data services. 2G networks employed technologies like GSM (Global System for Mobile Communications) and CDMA (Code Division Multiple Access). These networks allowed for clearer voice quality, text messaging, and limited data capabilities. Data transfer speeds were typically around 9.6 kbps, paving the way for simple internet access and services like SMS. The 2G era laid the foundation for more advanced mobile communication technologies [22]. Third Generation (3G): 3G wireless mobile communication introduced around the early 2000s, marked a significant advancement from 2G. It provided faster data speeds, enabling more robust internet access, multimedia services, and video calling. Technologies like UMTS (Universal Mobile Telecommunications System) and CDMA2000 improved data rates, offering speeds up to several megabits per second. This era saw the widespread adoption of smartphones and the growth of mobile internet usage. 3G networks laid the groundwork for the expansion of mobile data services and the evolution towards more advanced generations of wireless communication [22]. Fourth Generation (4G): 4G wireless mobile communication introduced in the late 2000s, brought substantial enhancements over 3G. It provided significantly faster data speeds, allowing for high-quality video streaming, online gaming, and improved internetbrowsing. Technologies like LTE (Long-Term Evolution) and WiMAX offered data rates reaching tens of megabits per second. 4G networks facilitated the rise of mobile apps, video sharing, and connected devices, driving the smartphone revolution and enabling a more connected digital lifestyle. This era marked a significant step toward achieving seamless high-speed mobile internet experiences [22]. Fourth Generation LTE-A (4.5G): A more sophisticated 4G-LTE model. In LTE-A, multiple antennas are combined for both broadcasters and receivers using MIMO technology. With MIMO, several signals and antennas may operate simultaneously, enabling LTE-A 3 times faster than traditional 4G. Wireless accessibility to triad traffic (data, voice, and video) out of any location in the globe was made possible by LTE-A, which also offered a greater system limit and less application server delay. LTE-A provides an upload rate of up to 90 Mbps and download speeds of over 42 Mbps [23]. Fifth Generation (5G): 5G wireless mobile communication introduced in the late 2010s, represents a transformative leap in connectivity. It offers ultra-fast data speeds, extremely low latency, and the capacity to connect a vast number of devices simultaneously. 5G enables advancements like augmented reality, virtual reality, autonomous vehicles, and the Internet of Things (IoT). Utilizing technologies like millimeter wave frequencies and massive MIMO, 5G networks provide multi-gigabit speeds and near-instantaneous communication, revolutionizing how we interact with technology and paving the way for new applications and innovations [23]. Sixth Generation (6G): Users will benefit from various 6G services like Massive-URLLC, eMBB, and Massive-eMBB. Massive URLLC includes approaches like OMA, with NOMA and assertion multiple access, the amount of bandwidth required might rise linearly as the quantity of devices increases. Other multiple access strategies may be employed to provide the optimum latency, reliability, and scalability trade-offs.