Dynamic spectrum access
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This document discusses cognitive radio and dynamic spectrum access (DSA). It defines cognitive radio as a new spectrum sharing paradigm that allows secondary users to access spectrum holes or white spaces. DSA allows for improved spectrum utilization by having secondary users dynamically search for and access idle spectrum bands, while avoiding interference to primary users through continuous monitoring. The key components and functions of cognitive radio are described, including spectrum awareness, cognitive processing, and spectrum access. Different DSA models like dynamic exclusive use, open sharing, and hierarchical access are also summarized.
![[1]Min Song,Chunsheng Xin,Yanxiao
Zhao,Xiuzhen Cheng “Dynamic Spectrum
Access: From Cognitive Radio To Network
Radio”,IEEE Wireless Communications,Feb 2012.
[2]Goutam Ghosh,Prasun Das,Subhajit
Chatterjee ,“Cognitive Radio And Dynamic
Spectrum Access-a Study”,International Journal
Of Next Generation Networks,Vol 6,No 1 ,March
2014](https://image.slidesharecdn.com/dynamicspectrumaccess-160701140312/85/Dynamic-spectrum-access-21-320.jpg)
Dynamic spectrum access
- 1. BY SANJANA PRASAD Research scholar PSG COLLEGE OF TECHNOLOGY 1601RL01
- 2. New spectrum sharing paradigm that allows secondary users to access the abundant spectrum holes or white spaces Promising technology to alleviate the spectrum scarcity problem Increase spectrum utilization Overcomes two types of interference ◦ Harmful interference caused by device malfunctioning ◦ Harmful interference caused by malicious user
- 3. Secondary users dynamically search for idle spectrum bands and temporarily access them for wireless communications To avoid interference to primary users (PU)’s secondary users continuously monitor the spectrum bands and yield to PU’s whenever PU start using a band . Dsa-made possible-cr technology
- 4. Functions of DSA : ◦ Spectrum awareness ◦ Cognitive processing ◦ Spectrum access COMPONENTS OF A COGNITIVE RADIO: ◦ Analog RF front end ◦ A digital processing engine ◦ Digital signal processor ◦ Customized FPGA
- 5. Dynamic exclusive use Open sharing model Hierarchial access model Dynamic Exclusive Use model: ◦ Basic structure of the current spectrum regulation policy are maintained in this model ◦ Spectrum bands licensed to services for exclusive use ◦ Improves spectrum efficiency by introducing flexibility
- 7. 2 approaches: Spectrum property rights Dynamic spectrum allocation Spectrum property rights: Allows licensees to sell and trade spectrum and to choose technology freely Economy,profit- play important role with the most profitable use of this limited resource
- 8. Dynamic spectrum allocation ◦ Improve efficiency through spectrum assignment by using spatial / temporal traffic statistics of different services
- 9. Open sharing model: Spectrum commons model Every user has equal rights to use the spectrum Applied for wireless services which operates in unlicensed ISM radio bands(WLAN) 3 TYPES: Uncontrolled commons Managed commons Private commons
- 10. Uncontrolled commons No entity has exclusive license to the spectrum band Managed – commons ◦ Imposes a limited form of structure of spectrum access ◦ Resource which is owned or controlled by a group of individuals or entities ◦ Characterized by restrictions on when and how the resource is used.
- 11. Private commons: ◦ Introduced by FCC. ◦ allows advanced technologies which enable multiple users to access the spectrum Hierarchial access models : Interweave Underlay Overlay
- 12. Different from overlay and underlay DSA models SU cannot access a licensed spectrum band as long as PU is active on the band PU-absolute priority on the spectrum band SU accessing the spectrum band must yield to PU whenever PU starts to access the band Also called oppurtunistic spectrum access.
- 13. SU’ s are constrained to oppurtunistically utilise spectrum holes or white spaces in the temporary ,spatial,and/or frequency domain. SU uses SR –sense the sorounding environment Selects one or more idle spectrum bands Switches the cognitive radio to the selected bands to transmit
- 15. Allows SU to transmit on a licensed spectrum band regardless of the PU accessing the band or not, subject to a constraint that the accumulated interference from all SU’s is tolerable by the PU ie. below some threshold 2 approaches ◦ UWB TECHNOLOGY ◦ INTERFERENCE TEMPERATURE
- 16. UWB Technology ◦ SU transmit power ◦ Interference < threshold Interference temperature ◦ SU transmit with higher power as long as the total interference from all SU’s on the band is below a threshold.
- 17. SU transmit on the licensed spectrum band even when the PU is accessing the band. Targets maintaining the PU performance SU are allowed to transmit simultaneously with PU s as long as there is no performance degradation 2 approaches: ◦ Channel coding ◦ Network coding
- 18. Channel coding Network coding Used when a PU transmitter is transmitting a PU packet that is known to a SU transmitter Su transmitter- can split into two parts- ◦ One to transmit its own SU packet ◦ Transmit PU packet to enhance the total power received such that SINR not degrade Su-relay – between disconnected or weakly connected nodes. While relaying a PU packet: ◦ SU may encode an SU packet onto the PU packet through network coding ◦ transport of the SU packet does not incur separate spectrum access ,without degrading the PU performance .
- 20. Accurate spectrum sensing Uncertainity of noise PUE attacks
- 21. [1]Min Song,Chunsheng Xin,Yanxiao Zhao,Xiuzhen Cheng “Dynamic Spectrum Access: From Cognitive Radio To Network Radio”,IEEE Wireless Communications,Feb 2012. [2]Goutam Ghosh,Prasun Das,Subhajit Chatterjee ,“Cognitive Radio And Dynamic Spectrum Access-a Study”,International Journal Of Next Generation Networks,Vol 6,No 1 ,March 2014