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17-779: UMTS Terrestrial Radio Access Network ( UTRAN ) is a collective term for the network and equipment that connects mobile handsets to the public telephone network or the Internet. It contains the base stations, which are called Node B 's and Radio Network Controllers (RNCs) which make up the Universal Mobile Telecommunications System (UMTS) radio access network . This communications network, commonly referred to as 3G (for 3rd Generation Wireless Mobile Communication Technology), can carry many traffic types from real-time Circuit Switched to IP based Packet Switched . The UTRAN allows connectivity between

34-533: A 50 Ω output load. Transistor output power is then limited to where The external load is, by convention, Z L = 50   Ω . {\displaystyle Z_{\text{L}}=50~\Omega .} Therefore, there must be some sort of impedance matching that transforms from Z o {\displaystyle Z_{\text{o}}} to Z L = 50   Ω . {\displaystyle Z_{\text{L}}=50~\Omega .} The loadline method

51-642: A very popular deployment). RF power amplifier A radio-frequency power amplifier ( RF power amplifier ) is a type of electronic amplifier that converts a low-power radio-frequency (RF) signal into a higher-power signal. Typically, RF power amplifiers are used in the final stage of a radio transmitter , their output driving the antenna . Design goals often include gain , power output, bandwidth, power efficiency, linearity (low signal compression at rated output), input and output impedance matching, and heat dissipation. RF amplifier circuits operate in different modes, called "classes", based on how much of

68-488: Is changing with the emergence of High Speed Downlink Packet Access ( HSDPA ), where some logic (e.g., retransmission) is handled on the Node B for lower response times. The utilization of WCDMA technology allows cells belonging to the same or different Node Bs and even controlled by different RNC to overlap and still use the same frequency (in fact, the whole network can be implemented with just one frequency pair ). The effect

85-514: Is not often used in RF applications because the finite switching speed of the active devices and possible charge storage in saturation could lead to a large I-V product, which deteriorates efficiency. Modern RF power amplifiers use solid-state devices , predominantly MOSFETs (metal–oxide–semiconductor field-effect transistors). The earliest MOSFET-based RF amplifiers date back to the mid-1960s. Bipolar junction transistors were also commonly used in

102-420: Is utilized in soft handovers . Since WCDMA often operates at higher frequencies than GSM (2,100 MHz as opposed to 900 MHz for GSM), the cell radius can be considerably smaller for WCDMA than for GSM cells as the path loss is frequency dependent. WCDMA now has networks operating in the 850–900 MHz band. In these networks, at these frequencies, the coverage of WCDMA is considered better than that of

119-720: The Radio Network Subsystem (RNS). There can be more than one RNS present in a UTRAN. There are four interfaces connecting the UTRAN internally or externally to other functional entities: Iu, Uu, Iub and Iur. The Iu interface is an external interface that connects the RNC to the Core Network (CN). The Uu is also external, connecting Node B with the User Equipment (UE). The Iub is an internal interface connecting

136-548: The UE (user equipment) and the core network . The RNC provides control functionalities for one or more Node Bs. A Node B and an RNC can be the same device, although typical implementations have a separate RNC that is located in a central office serving multiple Node Bs. Despite the fact that they do not have to be physically separated, there is a logical interface between them known as the Iub. The RNC and its corresponding Node Bs are called

153-427: The RF power amplifier include driving to another high-power source, driving a transmitting antenna and exciting microwave cavity resonators. Among these applications, driving transmitter antennas is most well known. The transmitter–receivers are used not only for voice and data communication but also for weather sensing (in the form of a radar ). RF power amplifiers using LDMOS (laterally diffused MOSFET ) are

170-604: The RNC with Node B. And at last, there is the Iur interface, which is an internal interface most of the time but can exceptionally be an external interface too for some network architectures. The Iur connects two RNCs with each other. Node B Node B corresponds to BTS ( base transceiver station ) in GSM . This is the hardware that is connected to the mobile phone network that communicates directly with mobile handsets. In contrast with GSM base stations, Node B uses WCDMA / TD-SCDMA as

187-485: The active device determines the class of the amplifier. A common trade-off in power amplifier design is the trade-off between efficiency and linearity. The previously named classes become more efficient, but less linear, in the order they are listed. Operating the active device as a switch results in higher efficiency, theoretically up to 100%, but lower linearity. Among the switch-mode classes are class D , class F and class E . The class D amplifier

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204-609: The air interface technology. As in all cellular systems, such as UMTS and GSM , the Node B contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with mobile devices, which move freely around it. In this type of cellular network, the mobile devices cannot communicate directly with each other but have to communicate with the NodeB. Traditionally, the Node Bs have minimum functionality, and are controlled by an RNC ( Radio Network Controller ). However, this

221-406: The cycle of the sinusoidal radio signal the amplifier (transistor or vacuum tube) is conducting current. Some classes are class A , class AB , class B , which are considered the linear amplifier classes in which the active device is used as a controlled current source, while class C is a nonlinear class in which the active device is used as a switch. The bias at the input of

238-594: The equivalent GSM network. Unlike in GSM, the cells' size is not constant (a phenomenon known as " cell breathing "). This requires a larger number of Node Bs and careful planning in 3G ( UMTS ) networks. Power requirements on Node Bs and user equipment (UE) are much lower. It is connected to RNC of UMTS network through IUB interface. A full cell site has a cabinet, an antenna mast and actual antenna. An equipment cabinet contains e.g. RF power amplifiers , digital signal processors and backup batteries . What you can see by

255-471: The most widely used power semiconductor devices in wireless telecommunication networks, particularly mobile networks . LDMOS-based RF power amplifiers are widely used in digital mobile networks such as 2G , 3G , and 4G and the good cost/performance ratio make them the preferred option for amateur radio . Impedance transformations over large bandwidth are difficult to realize, so conventionally, most wideband amplifiers are designed to feed

272-874: The past, up until they were replaced by power MOSFETs , particularly LDMOS transistors, as the standard technology for RF power amplifiers by the 1990s, due to the superior RF performance of LDMOS transistors. Generally speaking, solid-state power amplifiers contain four main components: input, output, amplification stage and power supply. MOSFET transistors and other modern solid-state devices have replaced vacuum tubes in most electronic devices, but tubes are still used in some high-power transmitters (see Valve RF amplifier ). Although mechanically robust, transistors are electrically fragile – they are easily damaged by excess voltage or current. Tubes are mechanically fragile but electrically robust – they can handle remarkably high electrical overloads without appreciable damage. The basic applications of

289-478: The side of a road or in a city center is just an antenna. However, the tendency nowadays is to camouflage the antenna (paint it the color of the building or put it into an RF-transparent enclosure). Smaller indoor nodes may have an antenna built into the cabinet door. A Node B can serve several cells, also called sectors, depending on the configuration and type of antenna. Common configuration include omni cell (360°), 3 sectors (3×120°) or 6 sectors (60 degree each, not

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