数学认知模型评介——加法事实存储与提取

本文介绍了国外心理学界近年来提出的有关加法事实存储与提取的 5个模型 ,即小值模型、网络恢复模型、联结强度分布模型、网络干扰模型以及比较模型 。

Interference Coordination for Secrecy Enhancement in Random Wireless Networks

The co-channel interference modeling is vital for evaluating the secrecy performance in random wireless networks,where the legitimate nodes and eavesdroppers are randomly distributed.In this paper,a new interference model is proposed from the userdominant perspective.The model can provide a better analytical assessment of secrecy performance with interference coordination for the presence of eavesdroppers.The typical legitimate is assumed to be located at the origin,and chooses the closest base station(BS) as its serving BS.The field of interferers is obtained by excluding the desired BSs(including the serving BS and its cooperative BS(s)).In contract with the exiting interference model,it is assumed that desired BSs and interferers belong to the same Poisson Point Process(PPP),and eavesdroppers are distributed according to another independent PPP.Based on this model,the average secrecy transmission capacity is derived in simply analytical forms with interference coordination.Analysis and simulation results show that the secrecy performance can be significantly enhanced by exploiting interference coordination.Furthermore,the average secrecy transmission capacity increases with increasing number of cooperative BSs.

Throughput analysis for relay-aided interference channel in cognitive radio networks

This paper considers a two-user Gaussian interference channel aided by a single relay. Two source-destination pairs and the relay share a single common chaunel, and the relay assists both sources in communicating the messages to their respective destinations. This paper mainly focuses on the ＂amplify-and-forward＂ （AF） relaying strategy for relay, and derives upper bound and lower bound on achievable sum rate accordingly. Next, the application of the above model in cognitive radio （CR） networks is considered. The schemes that can ensure the coexistence of the secondary user with the primary user are proposed, in the sense that there is no rate degradation for the primary user due to sharing of the channel. Further, the throughput of the secondary user in different communication scenarios is investigated.

Outage Probability Minimization for Cognitive Relay Network Under Interference Power Constraints

A cognitive relay network model is proposed, which is defined by a source, a destination, a cognitive relay node and a primary user. The source is assisted by the cognitive relay node which is allowed to coexist with the primary user by imposing severe constraints on the transmission power so that the quality of service of the primary user is not degraded by the interference caused by the secondary user. The effect of the cognitive relay node on the proposed cognitive relay network model is studied by evaluating the outage probability under interference power constraints for different fading environments. A relay transmission scheme, namely, decode-and-forward is considered. For both the peak and average interference power constraints, the closed-form outage expressions are derived over different channel fading models. Finally, the analytical outage probability expressions are validated through simulations. The results indicate that the proposed model has better outage probability than direct transmission. It is also found that the outage probability decreases with the increase of interference power constraints. Meanwhile, the outage probability under the average interference power constraint is much less than that under the peak interference power constraint when the average interference power constraint is equal to the peak interference power constraint.

An uplink power control algorithm using traditional iterative model for cognitive radio networks

Based on the analysis of the feature of cognitive radio networks, a relevant interference model was built. Cognitive users should consider especially the problem of interference with licensed users and satisfy the signal-to-interference noise ratio （SINR） requirement at the same time. According to different power thresholds, an approach was given to solve the problem of coexistence between licensed user and cognitive user in cognitive system. Then, an uplink distributed power control algorithm based on traditional iterative model was proposed. Convergence analysis of the algorithm in case of feasible systems was provided. Simulations show that this method can provide substantial power savings as compared with the power balancing algorithm while reducing the achieved SINR only slightly, since 6% S1NR loss can bring 23% power gain. Through further simulations, it can be concluded that the proposed solution has better effect as the noise power or system load increases.