Continuous Control Message Exchange in Distributed Cognitive Radio Networks
- 주제(키워드) Cognitive radio , Common control channel , overlay scheme , underlay scheme , WLAN , UWB
- 발행기관 Department of Computer Engineering Graduate of Ajou University
- 지도교수 Prof. Byeong-hee Roh
- 발행년도 2014
- 학위수여년월 2014. 7
- 학위명 석사
- 학과 및 전공 일반대학원 컴퓨터공학과
- 실제URI http://www.dcollection.net/handler/ajou/000000017794
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Since cognitive radios use the licensed spectrum opportunistically, they always suffer from primary user activities. Assume CR nodes are communicating in WLAN network. Meanwhile, a PU appeared on the CCC of some CR users. When the assigned CCCs are affected by PU activity, CR users must vacate the channel and negotiate for new CCC. Because data communication is suspended until they setup a new CCC, the reestablishment should be fast and reliable. Now consider the following cases, what if most of the spectrum is occupied and competition is high for the few spectrum holes? - Searching for new CCC becomes very difficult and it takes long time. And what if there are no spectrum holes or fails in the competition and could not find a new CCC? - Communication stops. Therefore, we must device a mechanism which allows the communication until new CCC is set up. In this thesis we propose UWB network for temporal communication until new CCC is reestablished on the WLAN. The main contribution of this thesis is two-fold: First, when a PU is detected on the CCC of a CR, the CR vacates the channel and searches for new spectrum hole. While doing so it needs to interrupt the communication, sense the whole spectrum to find unused spectrum hole, listen for beacons from other CR nodes in the network, exchange control message and share the spectrum. This process takes a longer time. But in our proposed idea, the CR does not need to repeat all steps. It simply changes its network from WLAN to UWB and continues the control message exchange. Therefore, there will not be communication interruption. Second, the continuous control message exchange enables the CR to find a new CCC faster because both transceivers are active in searching spectrum hole without any discontinuity.
more목차
TABLE OF CONTENTS iv
1. INTRODUTION 1
2. BACKGROUND AND RELATED WORKS 4
2.1 CCC Design Schemes and Their Effect on Control Messages Exchange 4
2.2 Related works 5
2.2.1 Sequence-based CCC design scheme 5
2.2.2 Group-based CCC design scheme 6
2.2.3 UWB CCC design scheme 8
3. FROM WLAN TO UWB 9
3.1 System Model 9
3.2 Operations 11
3.2.1 Network Change from WLAN to UWB 12
3.2.2 Learning the Network Environment 13
3.2.3 Establishing Routing Path (Neighbor Discovery) 13
3.2.4 Data Link Establishment 15
3.2.5 Synchronization of the Heterogeneous Networks 17
3.3 Analysis of Connection Failure Probability 19
3.3.1 Cases for the connection failure probability analysis 22
3.3.2 Spectrum efficiency improvement 25
3.3.3 Alternative Improvement for Connection Failure Probability 26
4. NUMERICAL ANALYSIS 27
4.1 Simulation Environment 27
4.2 Simulation Results 28
4.2.1 Connection Failure Probability 28
4.2.2 Improved Connection Failure Probability Through Multi-hop Communication 29
4.2.3 Spectrum Efficiency Improvement 30
5. CONCLUSION AND FUTURE WORKS 32
REFERENCES 33
