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1. Novel Converse for Device-to-Device Demand-Private Caching with a Trusted Server

   https://doi.org/10.1109/ISIT44484.2020.9174279  

   Wan, Kai; Sun, Hua; Ji, Mingyue; Tuninetti, Daniela; Caire, Giuseppe (August 2020, 2020 IEEE International Symposium on Information Theory (ISIT))

   This paper considers cache-aided device-to-device (D2D) networks where a trusted server helps to preserve the privacy of the users’ demands. Specifically, the trusted server collects the users’ demands before the delivery phase and sends a query to each user, who then broadcasts multicast packets according to this query. Recently the Authors proposed a D2D private caching scheme that was shown to be order optimal except for the very low memory size regime, where the optimality was proved by comparing to a converse bound without privacy constraint. The main contribution of this paper is a novel converse bound for the studied model where users may collude (i.e., some users share cache contents and demanded files, and yet cannot infer what files the remaining users have demanded) and under the placement phase is uncoded. To the best of the Author’s knowledge, such a general bound is the first that genuinely accounts for the demand privacy constraint. The novel converse bound not only allows to show that the known achievable scheme is order optimal in all cache size regimes (while the existing converse bounds cannot show it), but also has the potential to be used in other variants of demand private caching. 

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2. Coded Caching With Private Demands and Caches

   https://doi.org/10.1109/ISIT50566.2022.9834846  

   Gholami, Ali; Wan, Kai; Sun, Hua; Ji, Mingyue; Caire, Giuseppe (June 2022, 2022 IEEE International Symposium on Information Theory (ISIT))

   In the coded caching literature, the notion of privacy is considered only against demands. On the motivation that multi-round transmissions almost appear everywhere in real communication systems, this paper formulates the coded caching problem with private demands and caches. Only one existing private caching scheme, which is based on introducing virtual users, can preserve the privacy of demands and caches simultaneously, but at the cost of an extremely large subpacketization exponential in the product of the number of users (K) and files (N) in the system. In order to reduce the subpacketization while satisfying the privacy constraints, we propose a novel approach which constructs private coded caching schemes through private information retrieval (PIR). Based on this approach, we propose novel schemes with private demands and caches which have a subpacketization level in the order exponential with K instead of NK in the virtual user scheme. As a by-product, for the coded caching problem with private demands, a private coded caching scheme could be obtained from the proposed approach, which generally improves the memory-load tradeoff of the private coded caching scheme by Yan and Tuninetti. 

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3. A New Design Framework on D2D Coded Caching with Optimal Rate and Less Subpacketizations

   https://doi.org/10.1109/ISIT44484.2020.9174215  

   Zhang, Xiang; Yang, Xianfeng Terry; Ji, Mingyue (August 2020, 2020 IEEE International Symposium on Information Theory (ISIT))

   In this paper, we propose a new design framework on Device-to-Device (D2D) coded caching networks with optimal communication load (rate) but significantly less file subpacketizations compared to that of the well-known D2D coded caching scheme proposed by Ji, Caire and Molisch (JCM). The proposed design framework is referred to as the Packet Type-based (PTB) design, where each file is partitioned into packets according to their pre-defined types while the cache placement and user multicast grouping are based on the packet types. This leads to the so-called raw packet saving gain for the subpacketization levels. By a careful selection of transmitters within each multicasting group, a so-called further splitting ratio gain of the subpacketizatios can also be achieved. By the joint effect of the raw packet saving gain and the further splitting ratio gain, an order-wise subpacketization reduction can be achieved compared to the JCM scheme while preserving the optimal rate. In addition, as the first time presented in the literature according to our knowledge, we find that unequal subpacketizaton is a key to achieve subpacketization reductions when the number of users is odd. As a by-product, instead of directly translating shared link caching schemes to D2D caching schemes, at least for the sake of subpackeitzation, a new design framework is indeed needed. 

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4. Noncoordinated Individual Preference Aware Caching Policy in Wireless D2D Networks

   https://doi.org/10.1109/ICC40277.2020.9149007  

   Lee, Ming-Chun; Molisch, Andreas F. (June 2020, ICC 2020 - 2020 IEEE International Conference on Communications (ICC))

   Recent investigations showed that cache-aided device-to-device (D2D) networks can be improved by properly exploiting the individual preferences of users. Since in practice it might be difficult to make centralized decisions about the caching distributions, this paper investigates the individual preference aware caching policy that can be implemented distributedly by users without coordination. The proposed policy is based on categorizing different users into different reference groups associated with different caching policies according to their preferences. To construct reference groups, learning-based approaches are used. To design caching policies that maximize throughput and hit-rate, optimization problems are formulated and solved. Numerical results based on measured individual preferences show that our design is effective and exploiting individual preferences is beneficial. 

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5. RIS-Aided Interference Cancellation for Joint Device-to-Device and Cellular Communications

   https://doi.org/10.1109/ICCWorkshops59551.2024.10615548  

   Nguyen, Ly V; Swindlehurst, A Lee (June 2024, IEEE)

   Joint device-to-device (D2D) and cellular communication is a promising technology for enhancing the spectral efficiency of future wireless networks. However, the interference management problem is challenging since the operating devices and the cellular users share the same spectrum. The emerging reconfigurable intelligent surfaces (RIS) technology is a potentially ideal solution for this interference problem since RISs can shape the wireless channel in desired ways. This paper considers an RIS-aided joint D2D and cellular communication system where the RIS is exploited to cancel interference to the D2D links and maximize the minimum signal-to-interference plus noise (SINR) of the device pairs and cellular users. First, we adopt a popular alternating optimization (AO) approach to solve the minimum SINR maximization problem. Then, we propose an interference cancellation (IC)-based approach whose complexity is much lower than that of the AO algorithm. We derive a representation for the RIS phase shift vector which cancels the interference to the D2D links. Based on this representation, the RIS phase shift optimization problem is transformed into an effective D2D channel optimization. We show that the AO approach can converge faster and can even give better performance when it is initialized by the proposed IC solution. We also show that for the case of a single D2D pair, the proposed IC approach can be implemented with limited feedback from the single receive device. 

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