1. July 2009
doc.: IEEE /xxxxr0
July 2009
On-demand spectrum contention: a scalable and fair spectrum sharing protocol for TVWS coexistence
Date:
Authors:
Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Wendong Hu, STMicroelectronics
Ari Ahtiainen, Nokia

2. July 2009
doc.: IEEE /xxxxr0
July 2009
Abstract
This contribution presents an overview of the On-demand Spectrum Contention (ODSC) protocol for distributed and dynamic spectrum sharing in TV white-space.
Wendong Hu, STMicroelectronics
Ari Ahtiainen, Nokia

3. Outline Overview of ODSC protocol Illustrations of ODSC protocol
July 2009
Outline
Overview of ODSC protocol
Illustrations of ODSC protocol
Performance evaluation of ODSC protocol
Conclusion
Wendong Hu, STMicroelectronics

4. Inter-Network Spectrum Sharing in TVWS
July 2009
Inter-Network Spectrum Sharing in TVWS
Wendong Hu, STMicroelectronics

5. Overview of On-demand Spectrum Contention Protocol
July 2009
Overview of On-demand Spectrum Contention Protocol
Message-based, demand-driven, distributed spectrum sharing protocol
TVBD cells exchange contention messages, containing random contention numbers, to determine their rights of media access.
Designed for fair, low-overhead, QoS-aware spectrum sharing among the coexisting network cells.
Categorized into Coarse-grain (channel-based) and Fine-grain (frame-based) sharing
The basic principle is adopted in IEEE draft standard [1]
Wendong Hu, STMicroelectronics

6. Example of Channel-based ODSC
July 2009
Example of Channel-based ODSC
Wendong Hu, STMicroelectronics

7. Example of Frame-based ODSC
July 2009
Example of Frame-based ODSC
Provide a better QoS as compared to the channel-based approach
Wendong Hu, STMicroelectronics

8. Message Flow of ODSC Protocol
July 2009
Message Flow of ODSC Protocol
Wendong Hu, STMicroelectronics

9. Spectrum Contention Algorithm
July 2009
Spectrum Contention Algorithm
Spectrum Contention Number Generation
SCN = RANDOM (0, 2^16 ).
Wendong Hu, STMicroelectronics

10. Properties of ODSC Protocol
July 2009
Properties of ODSC Protocol
Require a standardized protocol for all (both heterogeneous and homogeneous) coexisting networks
Require a reliable and efficient inter-network communication mechanism for coexistence.
Require synchronized frame / superframe structure when finer grain spectrum sharing is employed.
Wendong Hu, STMicroelectronics

11. Performance Evaluation – Tool & Settings
July 2009
Simulation Tool
NS2 (Network Simulator) [2] Model for IEEE with ODSC implemented
Simulation Parameters
Single channel sharing
Size of super-frame: 16 frames
Frame size: 10ms
Self-coexistence Window size: 1ms
Simulation time: 10,000 seconds
Coexistence Scenarios (see more next slide)
Complete Graph scenarios
Cycle Graph scenarios
Wheel Graph scenarios
Evaluation Metrics
Fairness and Convergence Time
Wendong Hu, STMicroelectronics

12. Coexistence Scenarios
July 2009
Coexistence Scenarios
Complete
Cycle
Wheel
Wendong Hu, STMicroelectronics

13. Performance Evaluation – Results (1)
July 2009
Performance Evaluation – Results (1)
Wendong Hu, STMicroelectronics

14. Performance Evaluation – Results (2)
July 2009
Performance Evaluation – Results (2)
Wendong Hu, STMicroelectronics

15. Performance Evaluation – Results (3)
July 2009
Performance Evaluation – Results (3)
Wendong Hu, STMicroelectronics

16. Fairness and Convergence Time
July 2009
Fairness and Convergence Time
[2]
Wendong Hu, STMicroelectronics

17. Conclusion ODSC Protocol Efficient Fair Scalable Stable July 2009
enable efficient, scalable, and fair inter-network spectrum sharing
Efficient
Simple contention process (random number exchange)
Contentions are in parallel with data transmissions
Avoid collisions and the hidden node problem
Fair
Random number comparisons
On-demand iterative contention process
Scalable
Distributed decision making, no central arbiter needed.
Stable
Cooperation among networks to achieve the goals of fairness and efficiency of spectrum sharing
Wendong Hu, STMicroelectronics

18. July 2009
References
[1] IEEE P802.22™/ DRAFTv2.0 Draft Standard for Wireless Regional Area Networks Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Policies and procedures for operation in the TV Bands
[2] “The network simulator – ns-2,”
[3] Jain, R., Chiu, D.M., and Hawe, W. (1984) A Quantitative Measure of Fairness and Discrimination for Resource Allocation in Shared Systems. DEC Research Report TR-301
Wendong Hu, STMicroelectronics