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OBSAI
The Open Base Station Architecture Initiative (OBSAI) was a trade association created by Hyundai, LG Electronics, Nokia, Samsung and ZTE in September 2002 with the aim of creating an open market for cellular network base stations. The hope was that an open market would reduce the development effort and costs traditionally associated with creating base station products. Goal The OBSAI specifications provided the architecture, function descriptions and minimum requirements for integration of a set of common modules into a base transceiver station (BTS). It: * defined an internal modular structure of wireless base stations. * defined a set of standard BTS modules with specified form, fit and function such that BTS vendors can acquire and integrate modules from multiple vendors in an OEM fashion. * defined internal digital interfaces between BTS modules to assure interoperability and compatibility. * supported different access technologies such as GSM, Enhanced Data Rates for GSM E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Public Radio Interface
The Common Public Radio Interface (CPRI) standard defines an interface between Radio Equipment Control (REC) and Radio Equipment (RE). Oftentimes, CPRI links are used to carry data between cell sites and base stations. The purpose of CPRI is to allow replacement of a copper or coax cable connection between a radio transceiver (used example for mobile-telephone communication and typically located in a tower) and a base station (typically located at the ground nearby), so the connection can be made to a remote and more convenient location. This connection (often referred to as the Fronthaul network) can be a fiber to an installation where multiple remote base stations may be served. This fiber supports both single and multi mode communication. The fiber end is connected with the transceiver device called Small form-factor pluggable transceiver. The companies working to define the specification include Ericsson AB, Huawei Technologies Co. Ltd, NEC Corporation and Nokia. See also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyundai Group
Hyundai Group (; ) is a South Korean conglomerate founded by Chung Ju-yung. The first company in the group was founded in 1947 as a construction company. With government assistance, Chung and his family members rapidly expanded into various industries, eventually becoming South Korea's second chaebol. Chung Ju-yung was directly in control of the company until his death in 2001. The company spun off many of its better known businesses after the 1997 Asian financial crisis and founder Chung Ju-yung's death, including Hyundai Motor Group, Hyundai Department Store Group, and Hyundai Heavy Industries Group. The Hyundai Group now focuses on elevators and tourism to Mount Kumgang. Etymology The name "Hyundai" comes from the Korean word (hanja form), which means "modernity". History * In 1947, Hyundai Togun (Hyundai Engineering and Construction), the initial company of the Hyundai Group, was established by Chung Ju-yung. Hyundai Construction began operating outside of South K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Data
Digital data, in information theory and information systems, is information represented as a string of discrete symbols each of which can take on one of only a finite number of values from some alphabet, such as letters or digits. An example is a text document, which consists of a string of alphanumeric characters . The most common form of digital data in modern information systems is ''binary data'', which is represented by a string of binary digits (bits) each of which can have one of two values, either 0 or 1. Digital data can be contrasted with ''analog data'', which is represented by a value from a continuous range of real numbers. Analog data is transmitted by an analog signal, which not only takes on continuous values, but can vary continuously with time, a continuous real-valued function of time. An example is the air pressure variation in a sound wave. The word ''digital'' comes from the same source as the words digit and ''digitus'' (the Latin word for ''finger'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
User Equipment
In the Universal Mobile Telecommunications System (UMTS) and 3GPP Long Term Evolution (LTE), user equipment (UE) is any device used directly by an end-user to communicate. It can be a hand-held telephone, a laptop computer equipped with a mobile broadband adapter, or any other device. It connects to the base station Node B/eNodeB as specified in the ETSI 125/136-series and 3GPP 25/36-series of specifications. It roughly corresponds to the mobile station (MS) in GSM systems. The radio interface between the UE and the Node B is called ''Uu''. Functionality UE handles the following tasks towards the core network: * Mobility management * Call control * Session management * Identity management The corresponding protocols are transmitted transparently via a Node B, that is, Node B does not change, use or understand the information. These protocols are also referred to as ''Non Access Stratum Non-access stratum (NAS) is a functional layer in the NR, LTE, UMTS and GSM wireless tele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Network Controller
The Radio Network Controller (RNC) is a governing element in the UMTS radio access network (UTRAN) and is responsible for controlling the Node Bs that are connected to it. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile. The RNC connects to the Circuit Switched Core Network through Media Gateway ( MGW) and to the SGSN (Serving GPRS Support Node) in the Packet Switched Core Network. Interfaces The logical connections between the network elements are known as interfaces. The interface between the RNC and the Circuit Switched Core Network (CS-CN) is called Iu-CS and between the RNC and the Packet Switched Core Network is called Iu-PS. Other interfaces include Iub (between the RNC and the Node B) and Iur (between RNCs in the same network). Iu interfaces carry user traffic (such as voice or data) as well as control information (see ), and Iur interface is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quality Of Service
Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitatively measure quality of service, several related aspects of the network service are often considered, such as packet loss, bit rate, throughput, transmission delay, availability, jitter, etc. In the field of computer networking and other packet-switched telecommunication networks, quality of service refers to traffic prioritization and resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priorities to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. Quality of service is particularly important for the transport of traffic with special requirements. In particular, developers have introduced Voice ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MIMO
In radio, multiple-input and multiple-output, or MIMO (), is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wireless communication standards including IEEE 802.11n (Wi-Fi 4), IEEE 802.11ac (Wi-Fi 5), HSPA+ (3G), WiMAX, and Long Term Evolution (LTE). More recently, MIMO has been applied to power-line communication for three-wire installations as part of the ITU G.hn standard and of the HomePlug AV2 specification. At one time, in wireless the term "MIMO" referred to the use of multiple antennas at the transmitter and the receiver. In modern usage, "MIMO" specifically refers to a class of techniques for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting multipath propagation. Additionally, modern MIMO usage often refers to multiple data signals sent to different receivers (with one or more receiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Media Access Control
In IEEE 802 LAN/MAN standards, the medium access control (MAC, also called media access control) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium. The MAC sublayer and the logical link control (LLC) sublayer together make up the data link layer. The LLC provides flow control and multiplexing for the logical link (i.e. EtherType, 802.1Q VLAN tag etc), while the MAC provides flow control and multiplexing for the transmission medium. These two sublayers together correspond to layer 2 of the OSI model. For compatibility reasons, LLC is optional for implementations of IEEE 802.3 (the frames are then "raw"), but compulsory for implementations of other IEEE 802 physical layer standards. Within the hierarchy of the OSI model and IEEE 802 standards, the MAC sublayer provides a control abstraction of the physical layer such that the complexities of physical link control are invisible to the LLC and upper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rake Receiver
A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" called ''fingers'', that is, several correlators each assigned to a different multipath component. Each finger independently decodes a single multipath component; at a later stage the contribution of all fingers are combined in order to make the most use of the different transmission characteristics of each transmission path. This could very well result in higher signal-to-noise ratio (or Eb/N0) in a multipath environment than in a "clean" environment. The multipath channel through which a radio wave transmits can be viewed as transmitting the original (line of sight) wave pulse through a number of multipath components. Multipath components are delayed copies of the original transmitted wave traveling through a different echo path, each with a different magnitude and time-of-arrival at the receiver. Since each component contains the original infor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diversity Scheme
In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by using two or more Channel (communications), communication channels with different characteristics. Diversity is mainly used in radio communication and is a common technique for combatting fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver. Alternatively, a redundant forward error correction code may be added and different parts of the message transmitted over different channels. Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels. Diversity techniques The following classes of diversity schemes can be identified: * Time diversity: Multiple versions of the same signal are transmitted at dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baseband
In telecommunications and signal processing, baseband is the range of frequencies occupied by a signal that has not been modulated to higher frequencies. Baseband signals typically originate from transducers, converting some other variable into an electrical signal. For example, the output of a microphone is a baseband signal that is an analog of the applied voice audio. In conventional analog radio broadcasting the baseband audio signal is used to modulate an RF carrier signal of a much higher frequency. A baseband signal may have frequency components going all the way down to DC, or at least it will have a high ratio bandwidth. A modulated baseband signal is called a passband signal. This occupies a higher range of frequencies and has a lower ratio and fractional bandwidth. Various uses Baseband signal A ''baseband signal'' or ''lowpass signal'' is a signal that can include frequencies that are very near zero, by comparison with its highest frequency (for example, a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
