IEEE 802.22, is a

standard Standard may refer to: Symbols * Colours, standards and guidons, kinds of military signs * Standard (emblem), a type of a large symbol or emblem used for identification Norms, conventions or requirements * Standard (metrology), an object th ...

for wireless regional area network (WRAN) using white spaces in the

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...

(TV) frequency spectrum. The development of the IEEE 802.22 WRAN standard is aimed at using

cognitive radio A cognitive radio (CR) is a radio that can be programmed and configured dynamically to use the best wireless channels in its vicinity to avoid user interference and congestion. Such a radio automatically detects available channels in wireless spec ...

(CR) techniques to allow sharing of geographically unused spectrum allocated to the television broadcast service, on a non-interfering basis, to bring broadband access to hard-to-reach, low population density areas, typical of rural environments, and is therefore timely and has the potential for a wide applicability worldwide. It is the first worldwide effort to define a standardized air interface based on CR techniques for the opportunistic use of TV bands on a non-interfering basis. IEEE 802.22 WRANs are designed to operate in the TV broadcast bands while assuring that no harmful interference is caused to the incumbent operation: digital TV and analog TV broadcasting, and low power licensed devices such as wireless microphones. The standard was expected to be finalized in Q1 2010, but was finally published in July 2011. IEEE P802.22.1 is a related standard being developed to enhance harmful interference protection for low power licensed devices operating in TV Broadcast Bands.. IEEE P802.22.2 is a recommended practice for the installation and deployment of IEEE 802.22 Systems. IEEE 802.22 WG is a

working group A working group, or working party, is a group of experts working together to achieve specified goals. The groups are domain-specific and focus on discussion or activity around a specific subject area. The term can sometimes refer to an interdis ...

of IEEE 802 LAN/MAN standards committee which was chartered to write the 802.22 standard. The two 802.22 task groups (TG1 and TG2) are writing 802.22.1 and 802.22.2 respectively.

Technology

In response to a

notice of proposed rulemaking A Notice of Proposed Rulemaking (NPRM) is a public notice that is issued by law when an independent agency of the US government wishes to add, remove, or change a rule or regulation as part of the rulemaking process. The notice is an important ...

(NPRM) issued by the U.S.

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdicti ...

(FCC) in May 2004, the IEEE 802.22 working group on Wireless Regional Area Networks was formed in October 2004. Its project, formally called as ''Standard for Wireless Regional Area Networks (WRAN) - Specific requirements - Part 22: Cognitive Wireless RAN Medium Access Control ( MAC) and Physical Layer (

PHY PHY is an abbreviation for the physical layer of the OSI model and refers to the circuitry required to implement physical layer functions. PHY or Phy may also refer to: * Phy, the drug methadone * Phetchabun Airport (IATA code), Thailand See ...

) Specifications: Policies and procedures for operation in the TV Bands'' focused on constructing a consistent, national fixed

point-to-multipoint In telecommunications, point-to-multipoint communication (P2MP, PTMP or PMP) is communication which is accomplished via a distinct type of one-to-many connection, providing multiple paths from a single location to multiple locations. Point-to ...

WRAN that will use UHF/VHF TV bands between 54 and 862 MHz. Specific TV channels as well as the guard bands of these channels are planned to be used for communication in IEEE 802.22. The Institute of Electrical and Electronics Engineers (IEEE), together with the FCC, pursued a centralized approach for available spectrum discovery. Specifically each base station (BS) would be armed with a

GPS The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

receiver which would allow its position to be reported. This information would be sent back to centralized servers (in the USA these would be managed by the FCC), which would respond with the information about available free TV channels and guard bands in the area of the BS. Other proposals would allow local spectrum sensing only, where the BS would decide by itself which channels are available for communication. A combination of these two approaches is also envisioned. Devices which would operate in the TV white space band (TVWS) would be mainly of two types: Fixed and Personal/Portable. Fixed devices would have

geolocation Geopositioning, also known as geotracking, geolocalization, geolocating, geolocation, or geoposition fixing, is the process of determining or estimating the geographic position of an object. Geopositioning yields a set of geographic coordinates ...

capability with an embedded GPS device. Fixed devices also communicate with the central database to identify other transmitters in the area operating in TVWS. Other measures suggested by the FCC and IEEE to avoid interference include dynamic spectrum sensing and dynamic power control.

Overview of the WRAN topology

The initial drafts of the 802.22 standard specify that the network should operate in a point to multipoint basis ( P2MP). The system will be formed by base stations (BS) and

customer-premises equipment In telecommunications, a customer-premises equipment or customer-provided equipment (CPE) is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication circuit at the demarcation po ...

(CPE). The CPEs will be attached to a BS via a wireless link. The BSs will control the medium access for all the CPEs attached to it. One key feature of the WRAN Base Stations is that they will be capable of performing a ''cognitive sensing''. This is that the CPEs will be sensing the spectrum and will be sending periodic reports to the BS informing it about what they sense. The BS, with the information gathered, will evaluate whether a change is necessary in the channel used, or on the contrary, if it should stay transmitting and receiving in the same one.

An approach to the PHY layer

The PHY layer must be able to adapt to different conditions and also needs to be flexible for jumping from channel to channel without errors in transmission or losing clients (CPEs). This flexibility is also required for being able to dynamically adjust the bandwidth, modulation and coding schemes.

OFDMA Orthogonal frequency-division multiple access (OFDMA) is a multi-user version of the popular orthogonal frequency-division multiplexing (OFDM) digital modulation scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to ...

will be the modulation scheme for transmission in up and downlinks. With OFDMA it will be possible to achieve this fast adaptation needed for the BS's and CPEs. By using just one TV channel (a TV channel has a bandwidth of 6

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

; in some countries they can be of 7 or 8 MHz) the approximate maximum bit rate is 19 Mbit/s at a 30 km distance. The speed and distance achieved is not enough to fulfill the requirements of the standard. The feature ''Channel Bonding'' deals with this problem. Channel Bonding consists in using more than one channel for Tx / Rx. This allows the system to have higher bandwidth which will be reflected in a better system performance.

An approach to the MAC layer

This layer will be based on

technology. It also needs to be able to adapt dynamically to changes in the environment by sensing the spectrum. The MAC layer will consist of two structures: Frame and Superframe. A superframe will be formed by many frames. The superframe will have a superframe control header (SCH) and a preamble. These will be sent by the BS in every channel that it's possible to transmit and not cause interference. When a CPE is turned on, it will sense the spectrum, find out which channels are available and will receive all the needed information to attach to the BS. Two different types of spectrum measurement will be done by the CPE: ''in-band'' and ''out-of-band''. The in-band measurement consists in sensing the actual channel that is being used by the BS and CPE. The out-of-band measurement will consist in sensing the rest of the channels. The MAC layer will perform two different types of sensing in either in-band or out-of-band measurements: ''fast sensing'' and ''fine sensing''. Fast sensing will consist in sensing at speeds of under 1ms per channel. This sensing is performed by the CPE and the BS and the BS's will gather all the information and will decide if there is something new to be done. The fine sensing takes more time (approximately 25 ms per channel or more) and it is used based on the outcome of the previous fast sensing mechanism. These sensing mechanisms are primarily used to identify if there is an incumbent transmitting, and if there is a need to avoid interfering with it. To perform reliable sensing, in the basic operation mode on a single frequency band as described above (the "listen-before-talk" mode) one has to allocate quiet times, in which no data transmission is permitted. Such periodic interruption of data transmission could impair the QoS of cognitive radio systems. This issue is addressed by an alternative operation mode proposed in IEEE 802.22 called Dynamic frequency hopping (DFH) where data transmission of the WRAN systems are performed in parallel with spectrum sensing without any interruption.

Encryption, authentication, and authorization

Only the AES- GCM

authenticated encryption Authenticated Encryption (AE) and Authenticated Encryption with Associated Data (AEAD) are forms of encryption which simultaneously assure the confidentiality and authenticity of data. Programming interface A typical programming interface for ...

cipher algorithm is supported.

EAP-TLS Extensible Authentication Protocol (EAP) is an authentication framework frequently used in network and internet connections. It is defined in , which made obsolete, and is updated by . EAP is an authentication framework for providing the transport ...

EAP-TTLS Extensible Authentication Protocol (EAP) is an authentication framework frequently used in network and internet connections. It is defined in , which made obsolete, and is updated by . EAP is an authentication framework for providing the transport ...

must be used for

authentication Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicatin ...

and encryption key derivation. IEEE 802.22 defines an X.509v3 certificate profile which uses extensions for authenticating and

authorization Authorization or authorisation (see spelling differences) is the function of specifying access rights/privileges to resources, which is related to general information security and computer security, and to access control in particular. More fo ...

of devices based on information such as device manufacturer,

MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking tec ...

, and

FCC The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdictio ...

ID (the Manufacturer/ServiceProvider certificate, the CPE certificate, and the BS certificate, respectively). This could allow for a type of customer lock-in where the network providers refuse network access to devices that have not been vetted by manufacturers of the network providers' choice (i.e. the device must possess a private key of an X.509 certificate with a chain of trust to a manufacturer

certificate authority In cryptography, a certificate authority or certification authority (CA) is an entity that stores, signs, and issues digital certificates. A digital certificate certifies the ownership of a public key by the named subject of the certificate. Thi ...

(CA) that the network provider will accept), not unlike the

SIM lock SIM lock, simlock, network lock, carrier lock or (master) subsidy lock is a technical restriction built into GSM and CDMA mobile phones by mobile phone manufacturers for use by service providers to restrict the use of these phones to specific co ...

in modern cellular networks and

DOCSIS Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable televisio ...

"certification testers" in

cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...

networks.

Comparison with 802.11af

In addition to 802.22, the IEEE has standardized another white space cognitive radio standard, 802.11af. While 802.22 is a wireless regional area network (WRAN) standard, for ranges up to 100 km, 802.11af is a wireless LAN standard designed for ranges up to 1 km. Coexistence between 802.22 and 802.11af standards can be implemented either in centralized or distributed manners and based on various coexistence techniques.

References

{{DEFAULTSORT:Ieee 802.22 IEEE 802 Wireless networking standards