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

Wi-Fi

Wi-Fi (which stands for “Wireless Fidelity”, sometimes incorrectly abbreviated WiFi) is the name of the certification granted by the Wi-Fi Alliance, formerly WECA (Wireless Ethernet Compatibility Alliance), a group that guarantees compatibility between devices that use the 802.11 standard

The IEEE 802.11 specification (ISO/IEC 8802-11) is an international standard that defines the characteristics of a WLAN

Due to improper use of the terms (and for marketing reasons) the name of the standard is confused with the name of the certification

A Wi-Fi network is actually a network that complies with the 802.11 standard

To devices certified by the Wi-Fi Alliance they are allowed to use this logo:

With Wi-Fi you can create high-speed wireless local area networks as long as the equipment to be connected is not too far from the access point

In practice, Wi-Fi supports laptops, desktops, personal digital assistants (PDAs), or any other type of high-speed device with high-speed connection properties (11 Mbps or faster) within a radius of several dozens of meters indoors (20 to 50 meters generally) or within a radius of hundreds of meters outdoors

Wi-Fi providers are beginning to cover areas with a high concentration of users (such as train stations, airports, and hotels) with wireless networks. These areas are called “local coverage zones”

The 802.11 standard sets the lower levels of the OSI model for wireless connections that use electromagnetic waves, for example:

• The physical layer (sometimes abbreviated "PHY" layer) offers three types of information encoding
• The data binding layer consisting of two sublayers: Logical Binding Control (LLC) and Media Access Control (MAC)

The physical layer defines the modulation of radio waves and signaling characteristics for data transmission while the data link layer defines the interface between the computer bus and the physical layer, in particular an access method similar to that used in the Ethernet standard, and the rules for communication between network stations. Actually, the 802.11 standard has three physical layers that set alternative transmission modes:

Data Binding Layer (MAC)	802.2
	802.11
Physical cover (PHY)	DSSS	FHSS	Infrared

Any higher level protocol can be used on a Wi-Fi wireless network in the same way it can be used on an Ethernet network

Wifi standards

The original 802.11 standard, which allows 1 to 2 Mbps bandwidth, has been modified to optimize bandwidth (including 802.11a, 802.11b, and 802.11g standards, called 802.11 physical standards) or to specify components better to ensure greater security or compatibility. The table below shows the various modifications to the 802.11 standard and its meanings:

Name of the standard	Name	Description
802.11-1997	802.11	The 802.11-1997 standard is the original version of the 802.11 standard, specifying two "theoretical" transmission rates of 1 and 2 Mbps that are transmitted over infrared (IR) signals. It also defines the carrier sense multiple access with collision avoidance (CSMA/CA) protocol as an access method. Many of his weaknesses were corrected in the 802.11b standard
802.11a	Wi-fi 5	The 802.11a standard (called Wi-Fi 5) supports higher bandwidth (the maximum total throughput is 54 Mbps although in practice it is 30 Mbps). The 802.11a standard provides eight radio channels in the 5 GHz frequency band
802.11b	Wi-fi 1	The 802.11 standard offers a maximum total throughput of 11 Mbps (6 Mbps in practice) and has a range of up to 300 meters in an open space. Uses the 2.4 GHz frequency range with three radio channels available
802.11c	Combination of 802.11 and 802.1d	The combined standard 802.11c offers no interest to the general public. It is only a modified version of the 802.1d standard that allows you to combine the 802.1d with 802.11 compatible devices (at the data binding level)
802.11d	Internationalization	The 802.11d standard is a complement to the 802.11 standard that is intended to allow international use of local 802.11 networks. Allows different devices to exchange information in frequency ranges based on what is allowed in the device's home country
802.11e	Improvement of the quality of the service	The 802.11e standard is intended to improve quality of service at the data binding layer level. The goal of the standard is to define the requirements of different packets in terms of bandwidth and transmission delay to allow better audio and video transmissions
802.11f	Roaming	802.11f is a recommendation for access point vendors that makes products more compatible. It uses the IAPP protocol that allows a roaming user to clearly switch from one access point to another while on the move regardless of the branding of access points used in the network infrastructure. This property is also known simply as roaming
802.11g		The 802.11g standard offers high bandwidth (with a maximum total throughput of 54 Mbps but 30 Mbps in practice) in the 2.4 GHz frequency range. The 802.11g standard is compatible with the above standard, the 802.11b, which means that devices that support the 802.11g standard can also work with the 802.11b
802.11h		The 802.11h standard aims to combine the 802.11 standard with the European standard (HyperLAN 2; 802.11h h) and comply with European regulations related to frequency use and energy performance
802.11i		The 802.11i standard is intended to improve security in data transfer (by managing and distributing keys, and by implementing encryption and authentication). This standard is based on the AES (Advanced Encryption Standard) and can encrypt transmissions running on 802.11a, 802.11b and 802.11g technologies
802.11Ir		The 802.11Ir standard was developed so that you can use infrared signals. This standard has become technologically obsolete
802.11j		The 802.11 standard j it is for the regulation of japanese what the 802.11 h is to european regulation
802.11k		The 802.11k standard allows wireless switches and access points to calculate and assess the radio frequency resources of clients in a WLAN network, improving their management. It is designed to be implemented by software, simply updating computers, as long as both clients (adapters and WLAN cards) and infrastructure (access points and WLAN switches) are supported
802.11n	Wi-Fi 4	The 802.11n standard (called Wi-Fi 4) was a proposed modification to the 802.11-2007 standard to significantly improve network performance beyond previous standards, such as 802.11b and 802.11g, with a significant increase in speed. maximum transmission rate of 54 Mbps to a maximum of 600 Mbps. Currently the physical layer supports a speed of 300 Mbps, using two streams on a 40 MHz channel. Depending on the environment, the user could obtain a throughput of 100 Mbps
802.11p		The 802.11p standard operates on the 5.90 GHz and 6.20 GHz frequency spectrum, designed with the idea of using it for communication between vehicles and with on-road infrastructure. It is the basis of dedicated short-range communications (DSRC). It also adds wireless access in vehicle environments (WAVE). This improvement is widely used in the implementation of Intelligent Transport Systems (SIT)
802.11r	Fast Basic Service Set Transition	The 802.11r standard (called Fast Basic Service Set Transition) allows you to set security protocols that identify a device on the new access point before it leaves the current one and passes to it. This feature, which once enunciated seems obvious and indispensable in a wireless data system, allows the transition between nodes to take less than 50 milliseconds. This time lapse is short enough to maintain communication via VoIP without noticeable outages
802.11v		The 802.11v standard is used to allow remote configuration of client devices by allowing centralized (cellular network-like) or distributed station management through a data link layer (Layer 2) mechanism. This includes, for example, the network's ability to monitor, configure, and upgrade client stations. It also provides us with: Energy saving mechanisms with handheld VoIP Wi-Fi devices in mind positioning, to provide new location dependent services timing, to support applications that require very precise calibration; coexistence, which brings together mechanisms to reduce interference between different technologies in the same device
802.11w		The 802.11w standard is based on the 802.11i protocol and serves to protect WLAN networks against subtle attacks on WLAN frames. Not finished yet. TGw is working on improving the IEEE 802.11 media access control layer to increase the security of authentication and encoding protocols. Attempts are made to extend the protection provided by the 802.11i standard beyond data to management frames, responsible for the main operations of a network. These extensions will have interactions with IEEE 802.11r and IEEE 802.11u
802.11ac	Gigabit Wi-Fi	The 802.11ac standard (called Gigabit Wi-Fi or Wi-Fi 5) was a modification of the 802.11n standard that consisted of improving transfer rates up to 433 Mbps, theoretically achieving rates of 1.3 Gbitps using 3 antennas. It operates within the 5 GHz band, expanding the bandwidth up to 160 MHz (in 802.11n networks it was 40 MHz), uses up to 8 MIMO streams and includes high-density modulation (256 QAM)
802.11ax	Wi-Fi 6	The 802.11ax standard (called Wi-Fi 6 or Wi-Fi 6th Generation by the Wi-Fi Alliance) is designed to operate in the existing 2.4 GHz and 5 GHz spectrums. It introduces OFDMA to improve overall spectral efficiency
802.11be	Wi-fi 7	The 802.11be standard (called Wi-Fi 7 or Extremely High Throughput (EHT) by the IEEE). It operates in all three bands (2.4 GHz, 5 GHz and 6 GHz) to fully utilize spectrum resources. While Wi-Fi 6 was created in response to the growing number of devices in the world, the goal of Wi-Fi 7 is to deliver amazing speeds to every device with greater efficiency. Wi-Fi 7 features 320 MHz ultra-wide bandwidth, 4096-QAM, Multi-RU and Multi-Link operation to provide speeds 4.8 times faster than Wi-Fi 6 and 13 times faster than Wi-Fi 5

It is also important to mention the existence of a standard called "802.11b+". This is a patented standard that contains improvements over data flow. On the other hand, this standard has some interoperability gaps because it is not an IEEE standard

Range and data flow

The 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ax, 802.11be standards, called “physical standards”, are modifications of the 802.11 standard and operate in different modes, which allows them to achieve different transfer speeds of data according to their ranges

Date	IEEE Standard	Vel. max data	Bands	Channel size	Modulation	Antennas
1997	802.11b (WI-FI 1)	1 o 2 Mbps	2.4 GHz	20 MHz
1999	802.11a (WI-FI 2)	54 Mbps	5 GHz	20 MHz
2003	802.11g (WI-FI 3)	54 Mbps	2.4 GHz	20 MHz
2009	802.11n (WI-FI 4)	600 Mbps	2.4 y 5 GHz	20, 40 MHz
2013	IEEE 802.11ac (WI-FI 5)	3.5 Gbps	2.4 y 5 GHz	20, 40, 80, 80+80, 160 MHz	OFDM 256-QAM	4×4 MIMO DL MIMO
2019	802.11ax (WI-FI 6)	9.6 Gbps	2.4 y 5 GHz	20, 40, 80, 80+80, 160 MHz	1024-QAM OFDMA	8×8 UL/DL MU-MIMO
2021	802.11ax (WI-FI 6E)	9.6 Gbps	2.4, 5 y 6 GHz	20, 40, 80, 80+80, 160 MHz	1024-QAM OFDMA	8×8 UL/DL MU-MIMO
2024 (possibly)	802.11be (WI-FI 7)	46 Gbps	2.4, 5 y 6 GHz	Up to 320MHz	4096-QAM OFDMA (with extensions)	16×16 UL/DL MU-MIMO