论文标题
在大规模MIMO系统中进行大规模随机访问的时间表与争夺
Scheduling Versus Contention for Massive Random Access in Massive MIMO Systems
论文作者
论文摘要
大规模的机器类型通信协议通常是在用户之间的协调性的假设下设计的，因此需要大量的通信开销，因此是不切实际的。但是，有效的活动检测和无碰撞调度的最新进展表明，协调成本可能远小于调度的天真计划。这项工作考虑了一种场景，在这种情况下，大量具有零星流量的设备寻求访问大量的多输入多输出（MIMO）基站（BS），并探索了一种方法，在该方法中，设备活动检测之后是单个常见的反馈广播信息，这两者都用于将主动用户用于不同的传输插槽和分配orthogonal pinterots insult inders inders insuns insundation inders insuntion insuntion insuntion。将提出的协调通信方案与两个普遍的基于争论的方案进行了比较：编码的飞行员访问，该方案基于编码的插入式Aloha的原理，以及用于联合用户活动检测和渠道估计的近似消息传递方案。数值结果表明，预定的大规模访问可在每个插槽成功传输的数量以及由于干扰降低而以较小的反馈成本而获得的大幅收益。
Massive machine-type communications protocols have typically been designed under the assumption that coordination between users requires significant communication overhead and is thus impractical. Recent progress in efficient activity detection and collision-free scheduling, however, indicates that the cost of coordination can be much less than the naive scheme for scheduling. This work considers a scenario in which a massive number of devices with sporadic traffic seek to access a massive multiple-input multiple-output (MIMO) base-station (BS) and explores an approach in which device activity detection is followed by a single common feedback broadcast message, which is used both to schedule the active users to different transmission slots and to assign orthogonal pilots to the users for channel estimation. The proposed coordinated communication scheme is compared to two prevalent contention-based schemes: coded pilot access, which is based on the principle of coded slotted ALOHA, and an approximate message passing scheme for joint user activity detection and channel estimation. Numerical results indicate that scheduled massive access provides significant gains in the number of successful transmissions per slot and in sum rate, due to the reduced interference, at only a small cost of feedback.
