Are you new to telecommunication or learning about networking technology?
As this discipline is not easy, I want to share something to you in this article. You will learn common 9 concepts and 2 principles of tele-communication below.
1.9 common concepts of telecommunication
(1) Mobile communication
Mobile communication refers to communication in which one or both parties to a communication are in motion, including land, sea and air mobile communications. The frequency bands used are low frequency, intermediate frequency, high frequency, very high frequency and ultra high frequency. The mobile communication system is composed of a mobile station, a base station, and a mobile switching office. To communicate with a mobile station, the mobile switching office sends a call to the entire network through each base station, and the called station sends a response signal after receiving it, and the mobile switching office receives a response and allocates a channel to the mobile station and from the voice channel. A signaling is transmitted to ring it.
(2) Communication
Communication refers to the efficient delivery of messages from one place to another.
(3) Signal
A signal is a carrier of information and a tool for carrier information.
(4) Information
Information refers to content that is not known to the recipient and is to be transmitted, exchanged, stored or extracted.
(5) Interleaved coding
Strictly speaking, interleaving coding is not a type of channel coding, but an information processing means for modifying the channel. It does not have the most basic error detection and error correction function of channel coding, but only transforms the channel into a channel with random independent error, so as to be more suitable for the full application of channel coding for correcting random independent errors.
(6) HLR
The HLR generally manages several MSC/VCRs at the same time. It is a static database used by the management department for mobile user management. Each mobile user should be registered in an HLR. It is the central database of the GSM system.
(7) Handoff
Handoff refers to a technique for transferring an ongoing call and communication from one channel, cell to another, cell, and ensuring that communication does not cause an interruption. Handover is allowed between different radio channels, and also between different cells… In a broad sense, depending on the handover between carrier frequency, time slot, address code, cell, and different entities such as BSC and MSC, Corresponding to different types of switching.
(8) Wi-Fi
Wi-Fi is a technology that wirelessly connects terminals such as personal computers and handheld devices (such as PADs and mobile phones). Wi-Fi is a brand of wireless network communication technology and is owned by the Wi-Fi Alliance. The goal is to increase the patent fees for vendors that improve interoperability between wireless network products based on the IEEE 802.11 standard. At present, most people will confuse Wi-Fi and IEEE802.11. Even equating Wi-Fi with the wireless internet.
(9) 5G/4G/3G/2G
5G: 5G is generally seen as the fifth-generation cellular network technology that provides broadband access. The industry association 3GPP defines any system using “5G NR” (5G New Radio) software as “5G”, a definition that came into general use by late 2018. Others may reserve the term for systems that meet the requirements of the ITU IMT-2020. 3GPP will submit their 5G NR to the ITU.[1] It follows 2G, 3G and 4G and their respective associated technologies (such as GSM, UMTS, LTE, LTE Advanced Pro, etc.).
4G: 4G is the fourth generation of broadband cellular network technology, succeeding 3G. A 4G system must provide parameters defined by ITU in IMT Advanced. Potential and current applications include modified mobile web access, IP telephony, gaming services, high-definition mobile TV, video conferencing, and 3D television.
3G: 3G, short for third generation, is the third generation of wireless mobile telecommunications technology. It is the upgrade for 2G and 2.5G GPRS networks, for faster internet speed. This is based on a set of standards used for mobile devices and mobile telecommunications use services and networks that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile internet access, fixed wireless Internet access, video calls and mobile TV.
2G: 2G (or 2-G) is short for second-generation cellular technology. 2G cellular networks were commercial launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991.
Three primary benefits of 2G networks over their predecessors were that:
– Phone conversations were digitally encrypted.
– More efficient use of the radio frequency spectrum band.
– Data services for mobile, starting with SMS text messages.
2.Two basic principles of telecommunication
(1) Basic principles of OFDMA
In an OFDMA system, the entire channel bandwidth is divided into a plurality of orthogonal subcarriers, and each user allocates a different subcarrier group for carrying service data. Normally,
there are three subcarrier mapping modes of OFDMA, in which distributed mapping divides subcarriers into multiple groups, and each group of subcarriers is mapped to different users, so each of the user’s subcarriers are evenly distributed throughout the signal bandwidth; centralized mapping assigns a set of consecutive subcarriers to the same user, so each user’s signal is centralized distribution in the entire bandwidth; random mapping according to some random rule, in the system available subcarrier set, the user’s subcarriers are randomly allocated, therefore user signals are randomly distributed throughout the bandwidth.
(2) Basic principles of OFDM
The high-speed data stream is decomposed into multiple parallel low-speed data streams and transmitted simultaneously on multiple carriers. For low-speed parallel subcarriers, due to the number of periods is widened, and the delay spread caused by the multipath effect is relatively small. When a certain guard time is inserted into each OFDM symbol, the inter symbol interference can almost disappear slightly.
