Advisor ：Wei-Yeh Chen Student ：楊 于 世 Market-Equilibrium, Competitive, and Cooperative Pricing for Spectrum Sharing in Cognitive Radio Networks: Analysis and Comparison Advisor ：Wei-Yeh Chen Student ：楊　 于　 世 Reference D. Niyato, E. Hossain, “Market-Equilibrium, Competitive, and Cooperative Pricing for Spectrum Sharing in Cognitive Radio Networks: Analysis and Comparison,” IEEE Wireless Commun., vol. 7 , issue: 11 , part 1 , pp. 4273 - 4283 , Nov. 2008.

Outline Introduction Cognitive wireless network model Distributed implementation of the pricing models Numerical Results Conclusion

Introduction(1/2) In a cognitive radio network, frequency spectrum can be shared between primary users and secondary users, where the secondary users pay the primary users for radio resource usage. In a cognitive radio network, pricing model for spectrum sharing depends on the objective of spectrum trading, and therefore, the behaviors of spectrum sellers and spectrum buyers.

Introduction(2/2) In this paper, we investigate three different pricing models, namely, market-equilibrium, competitive, and cooperative pricing models for spectrum trading in a cognitive radio environment. In these pricing models, the primary service providers have different behaviors to achieve different objectives of spectrum trading.

Cognitive wireless network model Primary and Secondary Services Pricing Models

Primary and Secondary Services When a primary service is not fully utilizing its spectrum, it can sell portions of the available spectrum to the secondary users who are willing to buy the spectrum. In this way, a spectrum trading market is established(建立) where a seller and a buyer correspond(相當) to the primary and secondary services, respectively.

System model for spectrum sharing.

Pricing Models Market-Equilibrium-Based Pricing Model Competitive Pricing Cooperative Pricing

Market-Equilibrium-Based Pricing Model In this spectrum trading, market-equilibrium price denotes the price for which spectrum supplied by the primary service is equal to the spectrum demand from the secondary service. This market-equilibrium price ensures(保証) that there is no excess supply in the market and spectrum supply meets all spectrum demand.

Competitive Pricing In the competitive pricing model, it is assumed that a primary service is aware of the existence of other primary services and all of the primary services compete with each other to achieve the highest individual profit. The spectrum prices offered by other primary services, one primary service chooses the price for its own spectrum so that its individual profit is maximized.

Cooperative Pricing In the cooperative pricing model, it is assumed that all of the primary services know each other and they fully cooperate to obtain the highest total profit by selling spectrum to the secondary service.

Distributed implementation of the pricing models In a practical(實際的) cognitive radio environment, a primary service may not have the complete network information. In all of the pricing models, a primary service must learn the behavior of other entities from the history, and a distributed price adjustment algorithm is required which would gradually reach the solution.

Market-equilibrium pricing model S:供應 α: 學習率 t: 時間 Market-equilibrium pricing model

Competitive pricing model

Cooperative pricing model

Numerical Results(1/4) We observe that for a given vector of prices, a primary service sharing spectrum with secondary service can gain higher profit than that which does not share. If the price is too low, spectrum demand from secondary service becomes high, and the performance of the primary service degrades. When the price increases, the demand decreases.

Total profit and solutions of market-equilibrium, competitive, and cooperative pricing models.

Numerical Results(2/4) Spectrum supply depends largely on the number of primary users and their bandwidth requirements. Specifically, when the number of ongoing primary users and/or their bandwidth requirements increase, spectrum supply decreases and vice versa.

Demand and supply functions.

Numerical Results(3/4) The three different pricing models, when γ1 increases, the corresponding spectrum demand becomes larger, and therefore, primary service one can increase its offered price to gain higher profit. However, for primary service two, since the demand from the secondary service decreases, spectrum price, and consequently(因此), profit due to spectrum trading decreases.

Price adaptation under different channel qualities.

Numerical Results(4/4) Due to the nature of the demand function, for market equilibrium pricing, when the number of primary services increases, spectrum demand will increase with a corresponding increase in spectrum price. However, for competitive pricing, an increase in the number of primary services results in a higher degree of competition, and consequently, spectrum price decreases.

Price adaptation under different number of primary services.

Conclusion 之前想到說可以做交易機制中的拍賣，不過並沒有想到可以比較的對象，不過這篇讓我覺得其實可以讓拍賣機制與競爭機制做一個比較，因為拍賣機制我覺得也類似一種競爭機制，所以，想比較它們之間對效能上的差別。