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We study energy-efficient secure link adaptation for large-scale device-to-device (D2D) underlaid cellular networks, where base stations (BSs), D2D transmitters, and eavesdroppers (Eve nodes) are distributed as independent homogeneous Poisson point processes. First, we analyze the impact of the underlaid D2D network on the secrecy performance, i.e., secrecy spectral efficiency (SE) and secrecy energy...
We investigate the energy efficiency (EE) maximization problem under the scenario of Device-to-Device (D2D) communications underlaying cellular networks. By jointly considering time-varying channels and stochastic arrivals, we propose a distributed power allocation algorithm for both D2D user groups (DUGs) and cellular user terminals (CUTs) with long- term quality of service (QoS) provision. To effectively...
This paper considers the optimal energy-efficient transmission policy in time-sharing multiuser systems with a hybrid energy harvesting transmitter. The system operation energy is supplied by a constant energy source which is driven by a non-renewable resource and an energy harvester which harvests energy from its surrounding environment. Our goal is to maximize the energy-efficient transmission of...
We improve upon our previous upper bound on the secrecy capacity of the wiretap channel with multiple transmit antennas and single-antenna receivers, with noisy main channel state information (CSI) at the transmitter (CSI-T). Specifically, we show that if the main CSI error does not scale with the power budget at the transmitter $\bar{P}$, then the secrecy capacity is bounded above essentially by...
Energy harvesting (EH) two-hop communications are considered. The transmitter and the relay harvest energy from the environment and use it exclusively for transmitting data. A data arrival process is assumed at the transmitter. At the relay, a finite data buffer is used to store the received data. We consider a realistic scenario in which the EH nodes have only local causal information, i.e., at any...
We present a multi-user multiple-input multiple-output (MIMO) cognitive radio system consisting of a secondary receiver that deploys spatial multiplexing to decode signals from multiple secondary transmitters, under the presence of primary transmissions. The secondary receiver carries out minimum mean-squared error detection to decode the secondary data streams, while it performs spectrum sensing...
In this paper, we consider a T \times R massive MIMO system with up to R simultaneous links (T>> R>>1) and nonlinear amplifiers in each transmitter branch. The impact of a nonlinear amplification is analytically studied and accurate expressions for the spectral characterization of the transmitted signals, as well as the bit-error-rate (BER) are derived. The accuracy...
In this paper, we consider the channel estimation problem in millimeter wave (mmWave) wireless systems with large antenna arrays. By exploiting the inherent sparse nature of the mmWave channel, we develop a novel rate-adaptive channel estimation (RACE) algorithm, which can adaptively adjust the number of required channel measurements based on an expected probability of estimation error (PEE). To this...
Device-to-Device (D2D) communication is one of the key technologies to get to very high data rates in future 5G networks through offloading part of the cellular traffic onto D2D networks. While extensive research is targeted on addressing the many challenges D2D brings along in cellular networks, security issues have not gained much attention, especially that the direct connections between proximity...
In this work, we examine the secrecy capacity region of the block-fading broadcast channel with confidential messages (BCC) when the transmitter has limited knowledge of the channel. In particular, we consider a two-user communication system where the transmitter has one common message to be transmitted to both users and one confidential message intended to only one of them. The confidential message...
The article considers the joint optimization of artificial noise (AN) and information signal precoders in a MIMO wiretap interference network where the transmission of each user may be overheard by several MIMO-capable eavesdroppers. We use the theory of non-cooperative games to propose a distributed framework to optimize the covariance matrices of the information signal and AN at each link. To tackle...
This paper proposes a new Reverse Direction (RD) Medium Access Control (MAC) protocol to improve the throughput and energy efficiency of IEEE 802.11 Wireless Local Area Networks (WLANs). The proposed protocol allows a source device to transmit a burst of data frames to the intended destination device in a single channel access opportunity. After the successful reception of each data frame, the destination...
We address the resource allocation problem for energy- harvesting (EH) based OFDMA cooperative overlay cognitive radio networks with multiple primary users (PUs) and multiple secondary users (SUs), where PUs and SUs cooperate in terms of both information transmission and energy harvesting. Specifically, SU transmitters first apply the power splitting tech- nique to harvest energy from signals radiated...
We consider centralized cross-layer resource allocation for a device-to-device (D2D) video transmission system, given knowledge of the channel state information and the rate distortion information of the video streams, and propose an iterative algorithm for subcarrier assignment and power allocation. In the resource allocation, the performance improvement by applying the exact symbol error rate (SER)...
We investigate the physical layer security of synchronous multiple access transmissions using the Alamouti space-time block code in fading channels where multiple users communicate with a single intended receiver in the presence of an eavesdropper. We propose an artificial-noise-aided technique to secure the transmissions by having the Alamouti users collaborate with each other, without exchanging...
This paper studies a wireless network consisting of multiple transmitter-receiver pairs sharing the same spectrum where interference is regarded as noise. Previously, the throughput region of such a network was characterized for either one time slot or an infinite time horizon. This work aims to close the gap by investigating the throughput region for transmissions over a finite time horizon. We derive...
In this paper, we consider device-to-device (D2D) communication underlaying cellular networks, where D2D users harvest radio frequency (RF) power from uplink cellular transmissions. This paper addresses two important issues for energy harvesting-based D2D cellular networks. The first is how the energy harvested from cellular ambient RF signals affects the D2D spectral efficiency. Using tools from...
In this paper, an energy-incentive cooperative transmission (EICT) scheme is proposed for wireless ad hoc networks, where a node uses energy as reward to seek for cooperative transmission from neighboring nodes and then the cooperative node adopts a decode-and-forward (DF) protocol to relay data. An optimal time slot and power allocation algorithm is proposed to maximize the sum-rate under the constraints...
In this paper, a cooperative diffusion-based molecular communication system is considered where distributed receivers collaboratively determine a transmitter's signal. In this system, the receivers first make local hard decisions about the current transmitted bit and then report these decisions to a fusion center (FC). The FC combines the local hard decisions to make a global decision using an N-out-of-K...
In this paper, we have proposed an iterative space alternating generalized expectation maximization (SAGE) based semi-blind channel estimation technique for massive multiple-input multiple-output (MIMO) system in multi-cell pilot contamination prone scenario. The benefits of massive MIMO depend largely on the accuracy of channel state information (CSI) available at the base station (Transmitter)....
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