Abstract: This article discusses the development and deployment of 3G cellular Femto base stations, especially the technical difficulties faced in the last mile deployment and system expansion in dense urban connected residences. The article introduces Maxim's 3GPP TS25.104 compatible transceiver solution and a complete RF reference design. Why use Femto base stations? The third-generation 3GPP-based cellular system is designed to support a fully mobile multimedia experience. In many cases, the popularity of the system is limited by its reception, especially in residential and remote areas. In urban areas with dense residential areas, especially high-rise buildings, problems such as system expansion and quality of service (QoS) improvement are urgently needed. Faced with such requirements, "Femto" cellular base stations should be a logical choice. Base stations are generally divided into the following categories: + 45dBm: Macro cell base station, covering an area of ​​about 5km outdoors + 30dBm: microcell base station, covering an area of ​​about 0.5km + 15dBm: Femto base station, covering about 50m indoor residential or building area For residential deployments, Femto base stations can access the network through the public switched telephone network, usually using residential DSL lines. The mobile phone only communicates with the Femto base station at home, thus freeing users from relying on the macro cell base station. In high-rise buildings, Femto base stations can be connected to the building's wired Ethernet system, which also reduces the load on macro cellular base stations. Below, we briefly introduce the foundation of Femto base station deployment and understand how Maxim RF solutions provide key advantages for this technology. Improve cellular coverage The design of the cellular system needs to achieve the best balance between cell phone battery life, cell phone computing power consumption, and base station user load. In addition, with the continuous improvement of cellular standards, the performance advantages of advanced mobile DSPs can be fully utilized. Cellular system operators follow this trend and strive to provide more and better multimedia content, thereby increasing revenue and attracting more new users. Users enjoy the "ubiquitous" mobile Internet. As cellular phone users grow at a rate of 100 million per year, driven by this benefit, an efficient and highly competitive supply chain has been formed to ensure low prices and high performance. Comparison of broadband wireless communication and cellular RF services The development and deployment of broadband wireless systems and cellular system development plans go hand in hand to meet the development needs of the market / users. Initially, the so-called "Café" Wi-Fi® provided users with 802.11 Internet access, allowing users to use the Internet when they were staying nearby or eating in a restaurant. Subsequently, some cities began to construct Metro-Wi-Fi access points to provide services to commercial areas. This model has been very successful. In 2004, a better wireless access system was released, namely 802.16 WiMAX® (and WiBro® in Korea), with the aim of providing "Broadband Metro Wireless Access" services. The use of orthogonal frequency division multiplexing (OFDM) instead of single carrier modulation can allow these broadband wireless systems to overcome the multipath effect of cities, but the transmission power needs to be increased by 4 times. This is because the peak-to-average ratio (pk-avg) of OFDM 802.16d is close to 11 dB, while the WCDMA 3GPP pk-avg is 5 dB. Intel® has taken the lead in adopting WiMAX as the RF connection standard for Ultra Mobile PC (UMPC). The size of Ultra Mobile PC is defined as about 6 times that of ordinary cellular phones. Therefore, UMPC promotes WiMAX service, but because WiMAX requires a larger capacity battery, it is difficult to integrate it into an ultra-thin / flip phone. Launch Tower Construction A common obstacle to cellular and WiMAX deployment is the issue of tower construction and road occupation. The lease cost of road occupancy rights and the regulations of the municipal department on urban planning will greatly restrict the construction space and area of ​​these two systems. Cellular operators began the deployment and construction of systems as early as 20 years before WiMAX, and have obvious advantages in base station coverage and new system construction. Wired fixed residential business The wired residential access system is a powerful complement to residential WiMAX. Residential services generally include fiber-to-the-home (PON), telephone line DSL and cable TV interconnection access. In developed countries, these services benefit from the long-term development of network terminal equipment. PON is a relatively new access scheme, but the local exchange operator (LEC) of the network already has the right to use the road, and only needs to replace the old copper cable with new fiber. These services provide ready-made design platforms for Femto base station deployment, which we will discuss in detail below. Basic Femto base station deployment Figure 1 compares the connection between the traditional Node B Hongfengwo base station and the Femto base station. Figure 1. Comparison of traditional Node B macrocell base station connection with Femto base station connection In Figure 1, the left part is the direct connection between the cell phone and the cell tower. The house in the figure is a wooden structure, and the loss through the wall is relatively low, which is equivalent to being close to the macro cell base station to some extent. The right part is a high-rise concrete building, and the Femto base station is installed in the indoor or public office building. Connect Femto base stations via residential DSL lines or commercial wired Ethernet. In this case, the signal in the building can be very weak, and the Femto base station plays the role of a "personal, dedicated base station" and does not communicate with the macro cell base station. It should be pointed out that many baseband DSP vendors can now provide mature solutions to enable Femto base stations to overcome the interference of macro base station and other Femto base station signals. This is very important for Femto base stations. Closed Tricycle Electric Vehicle Three-Wheel Electric,Enclosed Electric Vehicle,Three-Wheeled Electric Vehicle,Closed Tricycle Electric Vehicle Jinan Huajiang environmental protection and energy saving Technology Co., Ltd , https://www.hjnewenergy.com