Focusing on the characteristics of selfishness of relay users and asymmetric network information in cognitive radio networks, a multi-user cooperative communication mechanism was proposed. Firstly, by modeling the cooperative communication as a labor market, a modeling method for the multi-user contract-based relay selection framework was investigated under the symmetric network information scenario. Then, to avoid the adverse selection problem due to the hidden-information of Secondary User (SU) before contract assignment, a contract-based relay selection model was proposed to incentivize the contribution of secondary users for ensuring cooperative communication. The experimental results show that, by hiring the secondary users with better channel condition or less relay cost, Primary User (PU) can obtain much more cooperative communication utility. The proposed multi-user contract-based cooperative communication framework can put forward new ideas for efficient utilization of spectrum resource.

In order to recommend trustworthy Web services, the differences between Web service recommendation and electronic commerce recommendation were analyzed, and then based on the collaborative filtering recommendation algorithm, a trustworthy Web service recommendation approach was proposed. At first, non-functional requirements of trustworthy software were evaluated. According to the evaluation results, similar users were filtered for the first time. Then, by using the rating information and basic information, the similar users were filtered for the second time. After finishing these two filtering procedures, the final recommendation users were determined. When using users' ratings information to calculate the similarity between the users, the similarity of the different services to the users was taken into consideration. When using users' basic information to calculate the similarity between the users, the Euclidean distance formula was introduced because of the nonlinear characteristics of the users. The problems of the dishonesty and insufficient number of users were also considered in the approach. At last, the experimental results show that the recommendation approach for trustworthy Web services is effective.

For the modulation recognition of seven kinds of Quadrature Amplitude Modulation (QAM) in non-cooperative communication, a new blind identification algorithm was proposed based on combined features. Based on the discussion and analysis of the cyclostationarity and the instantaneous amplitude distribution of the QAM signals, the algorithm used the combined features which were cyclostationary detection feature, fourth-order zero-conjugate cyclic accumulation feature and instantaneous envelope feature. The algorithm used the binary tree support vector machine as classifier to classify the seven Intermediate Frequency (IF) QAM signals. The simulation results show that the correct recognition rate of the algorithm reaches over 90% when the number of symbols is 1000 and the Signal-to-Noise Ratio (SNR) is more than 6dB.

QoS requirement is denoted by the range to support the flexible and heterogeneous QoS.According to the microeconomics theory and method,a Kelly/PSP model-based pricing strategy was presented to support the inter-group fairness.The ELSD(Equal Link Split Downstream) method was adopted to apportion the cost among group members,thus the intra-group fairness was provided.Based on the parallelized FCNN(Firing Coupled Neural Network),a parallel and intelligent QoS multicast routing algorithm was introduced,exploiting the inherent parallelism in FCNN fully and improving the scalability to the network size and the problem complexity significantly.Combining the above,a parallel,fair and intelligent QoS multicast routing mechanism was established.Simulation results have shown that the proposed mechanism is both effective and efficient,and the runtime efficiency of the proposed parallelized algorithm is higher than its corresponding serialized one.