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In this paper, we investigate the physical-layer network coding (PNC) scheme based on successive interference cancellation (SIC) in multi-way relay channels (MWRC). We consider a scenario where all users simultaneously transmit signals to the relay in the up-link stage while the relay broadcasts a coded message in the down-link stage. In order to extract the network codes from superimposed signals...
We propose a decentralized multi-cell aware opportunistic random access (MA-ORA) protocol that almost achieves the optimal throughput scaling in a K-cell random access network with one access point (AP) and N users in each cell. Under our MA-ORA protocol, users opportunistically transmit with a predefined physical layer data rate in a decentralized manner if the desired signal power to the serving...
Alice and Bob want to exchange information over an additive interference channel that also contains a malicious eavesdropper-jammer James who aims to disrupt this two-way communication. In the baseline model (motivated by wireless jamming scenarios), Alice and Bob transmit length-n q-arj encodings xA and xB respectively of their own messages. James observes the interference pattern z = xA + xB, and...
This paper discusses the contemporary problem of providing multiple-access (MAC) to a massive number of uncoordinated users. First, we define a random-access code for Ka-user Gaussian MAC to be a collection of norm-constrained vectors such that the noisy sum of any Ka of them can be decoded with a given (suitably defined) probability of error. An achievability bound for such codes is proposed and...
A general inner bound is given for the discrete memoryless broadcast channel with an arbitrary number of users and general message sets, a setting that accounts for the most general form of concurrent groupcasting, with up to exponentially many messages intended for any set of subsets of receivers. Achievability is based on superposition coding and rate-splitting, where each receiver jointly decodes...
This paper investigates the design of secondary access policies which exploit the temporal redundancy of the retransmission protocol employed by primary users (PU) to improve the spectral efficiency of wireless networks. Secondary users (SU) perform selective retransmissions in order to optimize the potential of interference cancellation at the receiver. The corrupted signals are selectively buffered...
This paper considers a multicarrier faster-than-Nyquist (FTN) transceiver architecture when spectrally efficient frequency division multiplexing (SEFDM) is also utilized at the transmitter. The received symbols are corrupted by both the introduced inter-symbol interference (ISI) due to FTN and inter-carrier interference (ICI) due to SEFDM. The interferences have to be eliminated to recover the transmitted...
In this paper, alternative signal set designs for higher order constellations based on combinatorial structures are proposed. These system designs are practical for 5th and future generation of systems. Non-Orthogonal Multiple Access (NOMA) is currently recognized as a promising multi-access technique for fifth generation (5G) networks. NOMA techniques ensure that multiple users share the same spectrum...
Recently, a new paradigm of multiple access (MAC) along with one eavesdropper to achieve secrecy transmissions has been getting in focus. However, all existing work on such multiple access wiretap channel (MAC-WT) mainly concentrates on the secrecy performance of the system as a whole from an information theoretic perspective. In this work, we investigate the secrecy performance of a single transmitter...
Real interference alignment is efficient in breaking-up a one-dimensional space over time-invariant channels into fractional dimensions. As such, multiple symbols can be simultaneously transmitted with fractional degrees-of-freedom (DoF). Of particular interest is when the one dimensional space is partitioned into two fractional dimensions. In such scenario, the interfering signals are confined to...
Network coding-based caching at base stations (BSs) is a promising caching approach to support massive content delivery over wireless networks. However, existing network coding-based caching designs do not fully explore and exploit the potential advantages. In this paper, we consider the analysis and optimization of a random linear network coding-based caching design in large-scale successive interference...
In this paper, a new spectrum sharing model referred to as riding on the primary (RoP) is proposed for wireless- powered IoT devices with ambient backscatter communication capabilities. The key idea of RoP is that the secondary transmitter harvests energy from the primary signal, then modulates its information bits to the primary signal, and reflects the modulated signal to the secondary receiver...
We consider nonlinear transceiver design for downlink multiuser multi-antenna secure communications with an external multi-antenna eavesdropper. The multi-antenna transmitter simultaneously transmits confidential-message-bearing signals and artificial noise (AN) using nonlinear Tomlinson Harashima precoding based on the limited channel state information feedback. For the proposed nonlinear secure...
Visible light communication (VLC) systems are expected to provide remarkably high speed indoor communications and effective ubiquitous connectivity. However, the key limitation of such systems is the narrow modulation bandwidth of the light sources. Based on this, non-orthogonal multiple access (NOMA) has been recently proposed as an effective method that can enhance considerably the spectral efficiency...
In this paper we propose a two-way spectrum sharing protocol for the overlay cognitive radio network consisting of two primary users (PUs) and two secondary users (SUs). One of the SUs acts as a relay to assist the communication between the PUs while at the same time allowing for two-way transmission with the other SU. The communication process is done in two phases. In the first phase, the PUs and...
In this paper, we propose a new full-duplex relay-assisted cognitive radio system model with an adaptive decoding algorithm at the secondary user, in order to maximize both primary and secondary achievable rates. We consider the uplink transmission and we compare the system's achievable rates obtained with both amplify-and-forward and decode-and-forward relaying in the single-carrier case. Then, we...
We consider an energy harvesting (EH) based cooperative relaying network, where two half-duplex relays can alternatively forward source data to the destination. The power-splitting technique is implemented at each relay. That is, part of the received source signal and inter-relay interference is allocated for the EH, while the remaining part is used for the information decoding (ID). The inter-relay...
Bit-patterned media recording (BPMR) has been developed into an aggressive technology for the next-generation of hard disc drives (HDDs), aiming to extend storage density as well as to integrate into an HDD [1].
In magnetic recording system, each track or sector may suffer different distortion and noise levels, for example, media noise, intersymbol interference (ISI)/inter-track interference (ITI), reader sensitivity (in case of multi-reader), resulting in unequal error rates or unequal ISI channels.
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