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We present a novel low-complexity scheme for cache-aided communication, where a multi-antenna base station serves multiple single-antenna mobile users. The scheme is based on dividing the users into meta-users, where all users in the same meta-user store the same content during the placement phase. The inter meta-user interference is mitigated by using the cache as well as zero forcing, while the interference between users of the same meta-user is mitigated by zero forcing. Compared to the current state of the art, this scheme is feasible for a wider range of parameters. Moreover, while still achieving the optimal number of degrees of freedom (DoF), the proposed scheme imposes the same or less complexity compared to all the known schemes for each set of parameters. Consequently, the proposed scheme enables practical implementation of cache-aided communication for a large number of users.
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HashBeam: Enabling Feedback Through Downlink Beamforming in Unsourced Random Access
Unsourced random access (URA) has emerged as a candidate paradigm for massive machine-type communication (mMTC) in next-generation wireless networks. While many excellent uplink schemes have been developed for URA, these schemes do not specify a mechanism for providing feedback regarding whether a user’s message was successfully decoded. While this may be acceptable in some mMTC scenarios, the lack of feedback is inadequate for applications that demand a high level of reliability. However, the problem of providing feedback to active users is complicated by the fact that the base station does not know the identities of the active users. In this paper, a novel downlink beamforming scheme called HashBeam is presented that enables the base station to provide feedback to the active users within URA, despite not knowing their identities. The key idea of this scheme is that the users’ channels and hashes of their messages may be used as proxies for their true identities. The proposed scheme may be adapted to any number of antennas at the base station and it is shown that the required number of channel uses is linear in the number of users to acknowledge.
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- Award ID(s):
- 2131106
- PAR ID:
- 10443173
- Date Published:
- Journal Name:
- Asilomar Conference on Signals, Systems, and Computers
- Page Range / eLocation ID:
- 692 to 697
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/IEEECONF56349.2022.10051879
