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Decentralized coded caching is applicable in scenarios where the server does not have enough knowledge about the entire cache network to perform centralized coordination during prefetching, such as when the server is uninformed of the number of active users and their identities in a wireless or mobile environment. Most of known decentralized strategies use random uncoded prefetching followed by coded...
We study frameless ALOHA with multiple base station (BS) cooperation, where the coverage area of each BS partially overlaps, and the BSs cooperate via a backhaul network to share successfully retrieved packets. The exact packet loss rate for networks with the arbitrary number of BSs is theoretically analyzed, which reveals how the throughput improvement is achieved. Computer simulations confirm that...
Utilization of millimeter-wave bands by next generation mobile networks is expected to make extremely high data rates realizable. However, at such high frequencies, phase noise (PHN) can significantly affect the performance of the communication system. Filter Bank Multi-Carrier systems with Offset Quadrature Amplitude Modulation (FBMC-OQAM) have received increased attention in recent years, but the...
This paper proposes optimum beamforming for a system consisting of a source, a full-duplex (FD) relay, an intended destination, and an eavesdropper. The source and destination are single-antenna nodes, whereas the FD relay is a multi-antenna node. Our objective is to find the optimum receive and transmit beamformers at the relay so that the secrecy rate is maximized. The joint optimization problem...
We consider the problem of group secret key generation through a multi-hop network modeled by a pair-wise independent network and propose a low complexity scheme which can guarantee strong secrecy. We assume that the legitimate transmitter only has the knowledge of the maximum number of precoded keys known to any helpers, where the precoded keys are the output of a precoder at the transmitter to be...
In this paper, we propose a fairness-aware energy-efficient power control scheme for device-to-device communications underlaying cellular networks, where multiple D2D pairs reuse the same subchannels allocated to one cellular user. Taking the maximum allowed transmit power and the minimum data rate requirement into accounts, we formulate the fairness-aware energy-efficient power control problem as...
Offloading users from an overloaded macro base station (BS) to a lightly loaded small cell BS is critical to alleviate the congestion of the macro BSs. However to overcome the signal-to-interference-plus-noise ratio (SINR) degradation of the offloaded users, offloading should be done in conjunction with an efficient interference management technique. Strict fractional frequency reuse (Strict-FFR)...
With the rapid development of wireless technology, free or cheap voice communication has become more and more popular. But this cost-effective voice technology based on Wi-Fi, Voice over WIFI (VoWIFI), is lacking mature management and control system, especially there is still no relevant research on its RAN performance. This paper has three mainly contributes: 1) in the indoor environment, we studied...
In this paper, analog-and-digital hybrid beamformer design is considered for millimeter-wave (mmWave) wideband multi-user (MU) multiple-input single-output (MISO)-OFDM downlink systems, where a single common analog beamformer is used for all subcarriers while a separate digital beamformer is applied to each subcarrier. By applying a signal-to-leakage-plus-noise ratio (SLNR) approach, an efficient...
The two-ray model has been used for modelling of wireless channels already for decades. However, since researchers and industry are pushing forward to unlock the millimeter wave bands, we revisited this model. We re-derive the break point distance based on a generalized first Fresnel zone. The simplified approximation formula — four times the product of antenna heights scaled by wavelength — is especially...
This paper employs wireless edge caching at relay nodes and proposes a cooperative hybrid caching placement scheme. The trade-off between the conventional caching schemes of most popular content (MPC) and largest content diversity (LCD) is investigated considering two degrees of flexibility. Specifically, we consider two design variables i.e., the number of relays employing the MPC scheme as well...
Recently it is shown that the maximum MIMO beamforming gain can be achieved using only one RF (radio frequency) chain. This is done by implementing the beamformer using Two analog pHase shIfters for each Coefficient (THIC). In this paper we analyze the quantization error of the beamforming coefficients (weights) when the phase shifters used in THIC are of finite resolution. An alternative THIC structure...
Terahertz (THz) band communication has abundant spectral resources to accommodate multiple broadband carriers. However, the strong path loss attenuation and the limited transmission power affect the maximum number of carriers that can be activated. A simple way to address this limitation consists in transmitting the same message from multiple transmission points, using Joint-Transmission (JT) Coordinated...
This paper considers an energy-efficient transmit design in a multiple-input single-output (MISO) wiretap channel. In particular, a transmitter sends one confidential message to a legitimate receiver, which must be kept perfectly secure from multiple external eavesdroppers. Assuming partial eavesdroppers' channel state information (ECSI) at the transmitter, we aim to design the transmit beamformer...
In a networked control system (NCS) where plants and controllers are connected through communication networks, it is important to decrease the number of times of communications under preserving of control performances such as optimality and stability. From this viewpoint, event-triggered control has been studied so far. In event-triggered control, the measured signal is sent to the controller only...
To realize a consensus problem based on wireless communications, it is necessary to consider several constraints caused by the natures of wireless communications such as communication error, coverage, capacity, multi-user interference, half-duplex and so on. This work focuses on half-duplex constraint and multi-user interference for a consensus problem and proposes a new Slotted-ALOHA that changes...
We propose a novel parallel essentially cyclic asynchronous algorithm for the minimization of the sum of a smooth (nonconvex) function and a convex (nonsmooth) regularizer. The framework hinges on Successive Convex Approximation (SCA) techniques and on a new global model that describes many asynchronous environments in a more faithful and exhaustive way with respect to state-of-the-art models. A key...
Generalized frequency division multiplexing (GFDM) is proposed as a candidate waveform to tackle new challenges posed on the physical layer for the fifth generation of wireless communication systems. In this paper, we propose a highly efficient algorithm for GFDM data detection on the basis of orthogonal approximate message passing (OAMP). We further combine with the conjugate gradient method and...
Physical layer security has become popular in recent years. In satellite communication systems, wire-tap users are easy to obtain information from satellite side for the range of the beam is broad. In this work, we consider the multi user scenario, by adopting the dynamic beam forming in satellite networks, the beam could be restricted into the small range, where wire-tap users could not obtain information...
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