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：本文研究了认知无线电启发的非正交多址接入在降低上行链路传输信息年龄方面的应用。具体而言，考虑了一个基于时分多址的现有网络，其中每个用户被分配一个专用时隙来传输其状态更新信息。CR-NOMA作为TDMA现有网络的附加功能被实施，它使每个用户能够通过共享其他用户的时隙获得更多的传输机会。通过考虑状态更新生成过程的随机性，本文建立了一个严格的分析框架，以推导出采用重传与不采用重传时CR-NOMA所实现的信息年龄表达式。数值结果验证了所提分析的准确性。研究表明，与TDMA相比，应用CR-NOMA可以显著降低信息年龄。此外，采用重传有助于降低信息年龄，尤其是在状态到达率较低的情况下。