This paper studies the application of cognitive radio inspired non-orthogonal multiple access (CR-NOMA) to reduce age of information (AoI) for uplink transmission. In particular, a time division multiple access (TDMA) based legacy network is considered, where each user is allocated with a dedicated time slot to transmit its status update information. The CR-NOMA is implemented as an add-on to the TDMA legacy network, which enables each user to have more opportunities to transmit by sharing other user's time slots. A rigorous analytical framework is developed to obtain the expressions for AoIs achieved by CR-NOMA with and without re-transmission, by taking the randomness of the status update generating process into consideration. Numerical results are presented to verify the accuracy of the developed analysis. It is shown that the AoI can be significantly reduced by applying CR-NOMA compared to TDMA. Moreover, the use of re-transmission is helpful to reduce AoI, especially when the status arrival rate is low.

翻译：本文研究了受认知无线电启发的非正交多址接入（CR-NOMA）在降低上行传输信息年龄（AoI）中的应用。具体考虑了一种基于时分多址（TDMA）的传统网络，其中每个用户被分配专用时隙以传输其状态更新信息。CR-NOMA作为TDMA传统网络的附加机制实现，使用户能够通过共享其他用户的时隙获得更多传输机会。本文建立了一个严格的分析框架，通过考虑状态更新生成过程的随机性，推导了CR-NOMA在有无重传情况下的AoI表达式。数值结果验证了所提分析的准确性。结果表明，与TDMA相比，应用CR-NOMA可显著降低AoI。此外，重传机制有助于减少AoI，特别是在状态到达率较低时。