【摘要】 在具有传输时限要求的认知无线电网络中,次用户需要机会式地在给定传输时限内使用无主用户占用的信道广播消息。针对此场景,文中提出一种新的传输时限下认知无线电网络的动态广播策略,允许各等待发送数据的次用户根据每个时隙载波侦听的观测、传输时限剩余时间和主用户占用信道模型实时调整发送概率。首先基于马尔可夫决策过程获得一种载波侦听理想观测假设下的最优策略和最大网络可靠性;然后据此提出一种适用于载波侦听实际观测能力的启发式策略,并通过马尔可夫决策过程建模获得此启发式策略的网络可靠性。仿真结果验证了理论分析的准确性,同时表明所提出的启发式策略的可靠性非常接近理想观测下的最大可靠性,并且明显优于最优静态策略的网络可靠性。更多还原

【Abstract】 In cognitive radio networks with delivery deadline requirements, secondary users need to opportunistically broadcast messages using the channel unoccupied by primary users(PUs) within a given delivery deadline.For this scenario, this paper proposes a new cognitive radio network dynamic broadcasting strategy under delivery deadline, which allows each secondary user(SU) to adjust the transmission probability according to the observation of carrier sensing in each slot, the remaining time before deadline expiration and the PU traffic model.Based on an ideal assumption on the observation of carrier sensing, this paper obtains an optimal broadcasting strategy and the maximum network reliability using Markov decision process(MDP).Then, accor-ding to a practical observation capability of carrier sensing, this paper proposes a heuristic broadcasting strategy and uses another MDP to obtain the network reliability of this heuristic strategy.Simulation results verify the accuracy of the analysis and show that the network reliability of the proposed heuristic strategyis very close to the maximum network reliability under the ideal observation, and is superior to that of the optimal statics trategy.更多还原