Wireless networks

Wireless networks are those that communicate by an un guided (wireless) transmission by electromagnetic waves. Transmission and reception is done via antennas

They have advantages such as rapid network installation without the need for cabling, allow mobility, and have fewer maintenance costs than a conventional network

Types

Depending on their coverage, they can be classified into different types:

• WPAN (Wireless Personal Area Network)
  In this type of personal coverage network, there are different technologies:
  • HomeRF
    Standard for connecting all mobile phones of the house and the computers through a central apparatus
  • Bluetooth
    Protocol following IEEE 802.15.1 specification
  • ZigBee
    Based on the IEEE 802.15.4 specification and used in applications such as home automation, which require secure communications with low data transmission rates and maximizing battery life, low power consumption
  • RFID
    Remote data storage and retrieval system for the purpose of transmitting the identity of an object (similar to a unique serial number) using radio waves
  • WLAN (Wireless Local Area Network)
    In local area networks we can find the technologies:
    • HiperLAN (High Performance Radio LAN)
      A standard group ETSI
    • Wi-Fi
      Follow IEEE 802.11 standard with different variants
    • WMAN (Wireless Metropolitan Area Network, Wireless MAN)
      For metropolitan area networks there are technologies:
      • WiMax (Worldwide Interoperability for Microwave Access)
        Worldwide Interoperability for Microwave Access is a wireless communication standard based on the IEEE 802.16 standard. WiMax is a protocol similar to Wi-Fi, but with more coverage and bandwidth. We can also find other communication systems such as LMDS (Local Multipoint Distribution Service)
      • WWAN (Wireless Wide Area Network, Wireless WAN)
        In these networks we find the technologies used in mobile phones:
        • GPRS (General Packet Radio Service)
          The transmission is digital
        • 0G
          Group of technologies used before the worldwide dissemination of mobile phones, usually military, in the United States, Canada, Finland, Sweden, Denmark, Spain, Philippines, Jamaica, Cuba, Chile, etc.
        • 1G
          Set of standards followed in the 1980s for mobile phone transmission, including NMT (Nordic Mobile Telephone) used in the Nordic countries; AMPS in the United States;
          TACS (Total Access Communications System) in the United Kingdom; C-450 in East Germany, Portugal and South Africa; TMA in Spain; Radiocom 2000 in France and RTMI in Italy. Multiple systems were implemented in Japan; three standards, TZ-801, TZ-802, TZ-803, developed by NTT, with a competition system operated by DDI using the JTACS standard
        • 2G
          A set of standards followed in the 1990s for mobile phone transmission, digital telephony protocols were introduced that, in addition to allowing more simultaneous links in the same bandwidth, allowed other services to be integrated into the same signal, such as sending text or page messages into a service called Short Message Service (SMS) and greater ability to send data from fax and modem devices. These included GSM (Global System for Mobile Communications); Cellular PCS/IS-136, known as TDMA (also known as TIA/EIA136 or ANSI-136) System regulated by the Telecommunications Industry Association or TIA; IS-95/cdmaONE, known as CDMA (Code Division Multiple Access); D-AMPS Digital Advanced Mobile Phone System; PHS (Personal Handyphon System) System originally used in Japan by NTT; DoCoMo in order to have a standard focused more on data transfer than the rest of the 2G standards
        • 3G
          Set of standards that replaced 2G by adding protocols for voice and data over mobile telephony using UMTS (Universal Mobile Telecommunications System). 3G technologies are the answer to the International Telecommunication Union's IMT-2000 specification. In Europe and Japan, the UMTS (Universal Mobile Telecommunication System) standard was selected, based on W-CDMA technology. UMTS is managed by the 3GPP organization, also responsible for GSM, GPRS and EDGE. 3G also envisaged the evolution of 2G and 2.5G networks. GSM and TDMA IS-136 that were replaced by UMTS, cdmaOne networks evolved to CDMA2000
        • 4G
          A set of standards that replaced 3G, the International Telecommunication Union (ITU) created the IMT-Advanced committee that defined its requirements. Among the technical requirements: Maximum data transmission speeds must be between 100 Mbit/s for high mobility and 1 Gbit/s for low mobility. The 3GPP (Long Term Evolution) LTE (Long Term Evolution) standard is not 4G because it does not meet the requirements defined by IMT-Advanced in peak transmission speed and spectral efficiency characteristics. However, ITU stated in 2010 that 4G candidates, such as that, could advertise as 4G. It is based entirely on the IP protocol, being a system and a network, which is achieved thanks to the convergence between cable and wireless networks. The WWRF (Wireless World Research Forum) intended 4G to be a fusion of technologies and protocols, not just a single standard, similar to 3G, that included technologies such as GSM and CDMA.1. NTT DoCoMo in Japan was the first to conduct experiments with fourth generation technologies, reaching 100 Mbit/s in a vehicle at 200 km/h. The firm launched the first 4G LTE technology-based services in December 2010 in Tokyo, Nagoya and Osaka
        • 5G
          Set of standards that are expected to replace 4G. It is expected to be common use by 2020. Swedish company Ericsson has managed to reach real 5 Gbps speeds, with live demonstrations of the pre-standard (pre-standard) 5G network technology standard. In November 2014, Huawei announced the signing of an agreement with Russian mobile operator Megafon to standardize and develop 5G test networks, in view of the 2018 FIFA World Cup

Features

Depending on the frequency range used to transmit, the means of transmission can be radio waves, terrestrial or satellite microwaves, and infrared, for example. Depending on the media, the wireless network will have some features or others:

• Radio waves
  Electromagnetic waves are omnidirectional, so satellite dishs are not required. Transmission is not sensitive to rain attenuations as it operates at not too high frequencies. In this range are the bands from the ELF ranging from 3 to 30 Hz, to the UHF band ranging from 300 to 3000 MHz, that is, it comprises the radio spectrum of 30 – 3000000 Hz
• Terrestrial microwave
  Parabolic antennas with a diameter of approximately three meters are used. They have a coverage of kilometers, but with the disadvantage that the emitter and receiver must be perfectly aligned. Therefore, they are used to use in point-to-point links over short distances. In this case, rain attenuation is more important as it is operated at a higher frequency. Microwaves comprise frequencies from 1 to 300 GHz
• Microwave satellite
  Links are made between two or more ground stations called base stations. The satellite receives the signal (called an upstream signal) in one frequency band, amplifies it and relays it in another band (downstream signal). Each satellite operates in specific bands. The frequency boundaries of microwaves, both terrestrial and satellite, with infrared and high-frequency radio waves mix quite a bit, so there may be interference with communications at certain frequencies
• Infrared
  Transmitters and receivers that modulate non-consistent infrared light are linked. They must be aligned directly or with a reflection on a surface. They can't get through the walls. Infrared ranges from 300 GHz to 384 THz

Applications

• The most important bands with wireless applications, of the frequency range covering radio waves, are VLF (navigation and submarine communications), LF (long wave AM radio), MF (medium wave AM radio), HF (shortwave AM radio), VHF (FM radio and TV), UHF (TV)
• Using terrestrial microwaves, there are different protocol-based applications such as Bluetooth or ZigBee to interconnect laptops, PDAs, phones, or other devices. Microwaves are also used for radar communications (speed detection or other remote object characteristics) and for DDT (digital terrestrial television)
• Satellite microwaves are used for satellite television broadcasting, long-distance telephone transmission and private networks
• Infrared has applications such as short-distance communication of computers with their peripherals. They are also used for remote controls, as they do not interfere with other electromagnetic signals, for example the television signal. One of the most commonly used standards in these communications is the IrDA (Infrared Data Association). Other uses of infrared are techniques such as thermography, which allows to determine the temperature of objects remotely