In the massive machine-type communication (mMTC) scenario, a large number of devices with sporadic traffic need to access the network on limited radio resources. While grant-free random access has emerged as a promising mechanism for massive access, its potential has not been fully unleashed. In particular, the common sparsity pattern in the received pilot and data signal has been ignored in most existing studies, and auxiliary information of channel decoding has not been utilized for user activity detection. This paper endeavors to develop advanced receivers in a holistic manner for joint activity detection, channel estimation, and data decoding. In particular, a turbo receiver based on the bilinear generalized approximate message passing (BiG-AMP) algorithm is developed. In this receiver, all the received symbols will be utilized to jointly estimate the channel state, user activity, and soft data symbols, which effectively exploits the common sparsity pattern. Meanwhile, the extrinsic information from the channel decoder will assist the joint channel estimation and data detection. To reduce the complexity, a low-cost side information-aided receiver is also proposed, where the channel decoder provides side information to update the estimates on whether a user is active or not. Simulation results show that the turbo receiver is able to reduce the activity detection, channel estimation, and data decoding errors effectively, while the side information-aided receiver notably outperforms the conventional method with a relatively low complexity.
翻译:联合活动检测、信道估计和数据解码用于无授权大规模随机接入
Translated abstract:
本文着力于从整体上开发先进的接收器,实现联合活动检测、信道估计和数据解码,以应对大规模机器类通信中的无授权随机接入机制。在现有的大多数研究中忽略了接收的导频信号和数据信号中的常见稀疏模式,并且未利用信道解码的辅助信息来进行用户活动检测。本文提出了一种基于双线性广义近似信息传递算法(BiG-AMP)的图珂德接收器。在该接收器中,所有接收的符号将被一起利用,以联合估计信道状态、用户活动和软数据符号,从而有效地利用了常见稀疏模式。同时,信道解码器提供的外部信息将有助于联合信道估计和数据检测。为了降低复杂度,还提出了一种低成本的辅助信息接收器,其中信道解码器提供的辅助信息用于更新用户是否处于活动状态的估计。仿真结果表明,图珂德接收器能够有效地降低活动检测、信道估计和数据解码的误差,而辅助信息接收器比传统方法具有较低的复杂度,并且表现优异。