论文标题
随机用户活动未包含多个访问
Unsourced Multiple Access With Random User Activity
论文作者
论文摘要
为了说明与物联网相关的大规模不协调的随机访问方案，Polyanskiy（2017）提出了一种新颖的多访问问题的新表述，通常称为未用的多个访问，所有用户都使用通用的代码书，并且接收器解码到消息的启动下。我们将这项开创性的工作扩展到了活动用户数量是随机且先验未知的情况下。我们为误导（MD）和错误警报（FA）定义了随机访问代码，并为高斯多访问通道绑定了一个随机编码可实现性。我们的约束捕捉了MD和FA之间的基本权衡。这表明，当目标MD和FA概率很高时，缺乏对活跃用户数量的知识会遭受少量的能源效率。但是，随着目标MD和FA概率的降低，能源效率的罚款变得很大。例如，在典型的IoT方案中，每位所需的每位所需的能量以达到我们界限的MD和FA概率低于0.1，仅比Polyanskiy（2017）在已知数量的活动用户中所预测的能量比BOND BOND BOND BOND BOND BOND BOND的能量高0.5-0.7 dB。当目标MD和/或FA概率为0.001时，此差距增加到3-4 dB。考虑到MD和FA，我们使用界限将带有多包装接收的插入式Aloha的能源效率基准，该解码器将干扰视为噪声，以及一些最近提出的编码方案。数值结果表明，当目标MD和FA概率很高时，估计活跃用户的数量，然后将此估计视为真实值是有效的，并使用对已知活跃用户数量的情况良好的编码方案。但是，当对MD和FA概率的需求严格时，这种方法变得效率低下。
To account for the massive uncoordinated random access scenario, which is relevant for the Internet of Things, Polyanskiy (2017) proposed a novel formulation of the multiple-access problem, commonly referred to as unsourced multiple access, where all users employ a common codebook and the receiver decodes up to a permutation of the messages. We extend this seminal work to the case where the number of active users is random and unknown a priori. We define a random-access code accounting for both misdetection (MD) and false alarm (FA), and derive a random-coding achievability bound for the Gaussian multiple access channel. Our bound captures the fundamental trade-off between MD and FA. It suggests that the lack of knowledge of the number of active users entails a small penalty in energy efficiency when the target MD and FA probabilities are high. However, as the target MD and FA probabilities decrease, the energy efficiency penalty becomes significant. For example, in a typical IoT scenario, the required energy per bit to achieve both MD and FA probabilities below 0.1, predicted by our bound, is only 0.5-0.7 dB higher than that predicted by the bound in Polyanskiy (2017) for a known number of active users. This gap increases to 3-4 dB when the target MD and/or FA probability is 0.001. Taking both MD and FA into account, we use our bound to benchmark the energy efficiency of slotted ALOHA with multi-packet reception, of a decoder that treats interference as noise, and of some recently proposed coding schemes. Numerical results suggest that, when the target MD and FA probabilities are high, it is effective to estimate the number of active users, then treat this estimate as the true value, and use a coding scheme that performs well for the case of known number of active users. However, this approach becomes energy inefficient when the requirements on MD and FA probabilities are stringent.
