4.7 Article

A Joint User Activity Detection and Channel Estimation Scheme for Packet-Asynchronous Grant-Free Access

期刊

IEEE WIRELESS COMMUNICATIONS LETTERS
卷 11, 期 2, 页码 338-342

出版社

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
DOI: 10.1109/LWC.2021.3127680

关键词

Delays; Partial transmit sequences; Matching pursuit algorithms; Encoding; Uplink; Ultra reliable low latency communication; Receivers; Packet-asynchronous grant-free; rateless codes; user activity detection and channel estimation; prior-aided compressive sensing

资金

  1. Key Research and Development Program of China [2018YFB1801102]
  2. National Natural Science Foundation of China [61631013]
  3. Foundation for Innovative Research Groups of the National Natural Science Foundation of China [61621091]
  4. Civil Aerospace Technology Project [D040202]
  5. Tsinghua-Qualcomm Joint Project
  6. Tsinghua University Initiative Scientific Research Program [20193080005]

向作者/读者索取更多资源

This study proposes a novel approach to achieve low-latency GF access under imperfect conditions by improving the algorithm and frame structure. This method is of great significance for meeting the low-latency requirement in massive access of short packets.
Grant-free (GF) access has been viewed as a promising solution to meet the low-latency requirement in massive access of short packets due to the cancellation of the procedure of requesting for the grant. While most GF schemes are realized in a synchronous way, a recently proposed packet-asynchronous GF (PA-GF) scheme can further reduce the overall delay. However, its performance was only validated under the ideal conditions, i.e., perfect active user detection (AUD) and channel estimation (CE). In this letter, in order to realize timely AUD and CE for PA-GF practically, a novel frame structure for multiplexing pilot sequences and data is proposed together with a sliding window detection algorithm. A modification of the orthogonal matching pursuit (OMP)-the prior-aided OMP (PA-OMP)-is also proposed. Numerical results show that the proposed algorithm achieves the low-latency advantage of PA-GF under imperfect AUD and CE conditions.

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