Introduction to wireless network technology-Analysis of the 4G stack system framework

Introduction to wireless network technology-Analysis of 4G stack system framework-4g stack system framework-this technology provides faster data rates and greater system capacity. The target peak speed is: 1 Gbps or more for low-speed mobile, hotspot coverage, and 100 Mbps for high-speed mobile and wide-area coverage. The above performance indicators mainly rely on two methods: Improving the spectrum efficiency and expanding the system bandwidth. To achieve a 1 Gbps peak rate, the 4G system requires a system bandwidth of MHz in width. However, it is almost impossible to allocate a MHz continuous spectrum in a band below 3 GHz, in the high-frequency band, it is difficult to achieve seamless global coverage and high-speed mobile (the operator needs to deploy 4G systems based on the existing site, so it is difficult to widely use the relay and distributed antenna technology ), therefore, we need to use a spectrum of less than 3 GHz at the same time. That is to say, the 4G system will be a cascade system, and the above two discrete frequencies need to be used at the same time, which forms an important feature of the 4G system. The stack-based 4G system framework the future 4G system can be composed of the broadband mobile communication (BMC) subsystem and the broadband hotspot access (BHA) subsystem. The BMC subsystem works in lower frequencies (such as IMT-2000 frequencies below 3 GHz) and provides wide area coverage and high mobility. To achieve 4G performance indicators, you can consider using a bandwidth slightly larger than E3G, such as 20 ~ 40 MHz. BHA sub-systems work in high-frequency segments (for example, 3GHz-5GHz may be allocated to a new 4G band). In order to achieve 4G performance indicators (fixed mobile peak rate of 1 Gbps ), A large bandwidth (up to 100 MHz) is required ). The two subsystems www.2cto.com should be highly integrated (such as using similar designs) to achieve flexible access, scheduling and switching between the two systems. That is, when a user is in a fixed or low-speed mobile environment and is in the hotspot coverage, the user can access the BHA subsystem to achieve high data rate broadband access. You can switch to the BMC subsystem when the user is out of hotspot coverage or in a high-speed mobile environment. Since the BHA subsystem has covered the center area of the residential area, the BMC subsystem can use limited frequency resources in the edge area of the residential area to achieve higher performance. The coverage of BHA is limited by the transmission characteristics of the frequency band, which is about several hundred meters. In dense urban areas, the distance between base stations deployed by operators has already dropped to several hundred meters, so the BHA sub-system can achieve continuous coverage to a certain extent, however, the high-speed mobile users in the coverage area should still be carried by BMC. In normal urban areas, suburbs, and rural areas, the distance between carrier base stations may be extended to several kilometers. without adding new sites, the BHA subsystem cannot provide continuous coverage, the BHA subsystem will only be used to provide hotspot broadband access services in specific regions. The gap between the BHA coverage areas is covered by BMC. In normal urban areas, suburbs, and rural areas, operators may consider adding BHA base stations or trunk stations in necessary areas to expand the coverage of the BHA sub-system. Based on the basic system framework, the stack system framework www.2cto.com with a Relay system can be used to extend the coverage of the BHA subsystem. As an extension of the BHA subsystem, the Relay system is only used for fixed and low-speed mobile users. High-speed mobile users are still provided by the BMC subsystem. Relay Technology and distributed antenna technology still require further research. Even if the technical problem is solved, the operators are subject to a lot of restrictions in adding a large number of new base stations and RelayStation (RS, it is also difficult to rely on the relays and distributed antenna system to provide global coverage. It should be used in some specific scenarios as an effective supplement. The new 4G air interface, including the BMC and BHA sub-systems, can centrally use the 4G licensed band for wide-area and Metro scenarios with a coverage of more than 100 meters, however, the existing WLAN and WPAN technology standards are used to achieve local and personal domain coverage of less than 100, and the interconnection and switching between wide-area/metro systems and local/personal domain systems are achieved through heterogeneous interfaces. The cascade system framework based on discontinuous frequencies is determined by the available spectrum characteristics of the 4G system and the actual subordinate requirements of operators (new site sites cannot be greatly added. Based on this system framework, there are still a lot of problems to be studied, but it is expected that this will become a basic feature of 4G systems. This article is from the fat shark network.