IEEE 802.22
IEEE 802.22, is a
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.[3] 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.[1] IEEE 802.22 WG is a working group 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 (NPRM) issued by the U.S. Federal Communications Commission (FCC) in May 2004, the IEEE 802.22 working group on Wireless Regional Area Networks was formed in October 2004.[4]
Its project, formally called as Standard for Wireless Regional Area Networks (WRAN) - Specific requirements - Part 22: Cognitive Wireless RAN Medium Access Control (
The
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 (
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.
An approach to the MAC layer
This layer will be based on cognitive radio 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)[5] 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 cipher algorithm is supported.[6]
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 (CA) that the network provider will accept), not unlike the SIM lock in modern cellular networks and DOCSIS "certification testers" in cable networks.
Comparison with 802.11af
In addition to 802.22, the IEEE has standardized another white space cognitive radio standard,
See also
- IEEE 802.11af, a standard for wireless LANs in TV white space
- Geolocation Database
- How is spectrum sensing done
References
- ^ IEEE. Retrieved January 18, 2009.
- S2CID 216588272.
- .
- ^ "IEEE Starts Standard to Tap Open Regions in the TV Spectrum for Wireless Broadband Services". News release. IEEE Standards Association. October 12, 2004. Archived from the original on February 7, 2009. Retrieved August 19, 2011.
- S2CID 40049.
- ^ IEEE 802.22-2011 § 8.4.1, p. 281
- ^ IEEE 802.22-2011 § 8.1.2, p. 252
- ^ IEEE 802.22-2011 § 8.5, p. 286
- ^ IEEE 802.22-2011 § 8.5, pp. 286-292
- ^ a b Lekomtcev, Demain; Maršálek, Roman (June 2012). "Comparison of 802.11af and 802.22 standards – physical layer and cognitive functionality". elektrorevue. Retrieved 2013-12-29.
- ^ Thiel, Justin (2006–2007). "Metropolitan and Regional Wireless Networking: 802.16, 802.20 and 802.22". Retrieved 2013-12-31.
- S2CID 28929874.
- S2CID 3134504.