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This paper investigates a wireless-powered two-way relay network (WP-TWRN), in which two sources exchange information with the aid of one amplify-and-forward (AF) relay. Contrary to the conventional two-way relay networks, we consider the scenario that the AF relay has no embedded energy supply, and it is equipped with an energy harvesting unit and rechargeable battery. As such, it can accumulate...
Mobile gadgets including smartphones and laptops nowadays support both Wi-Fi and Bluetooth together. The two protocols coexist in the 2.4GHz ISM band while sharing a single antenna in order to meet constraints on form-factor. We call this kind of devices "Dual- stack devices" in this paper. Since Wi-Fi and Bluetooth on dual-stack devices work in TDM (Time Division Multiplexing) manner, the...
In energy harvesting communications, the transmitters have to adapt transmission to the availability of energy harvested during communication. The performance of the transmission depends on the channel conditions which vary randomly due environmental changes. In this paper, we consider the problem of power allocation taking into account the energy arrivals over time and imperfect channel state information...
In this paper, we present an efficient medium access control (MAC) protocol based on IEEE 802.11 DCF, which minimizes the unfairness problem of two way vehicle ad hoc networks. Geographically highly dynamic topology in vehicle ad hoc networks lead to unfairness problem. Unfairness problem has two aspects: higher velocity vehicles cannot transmit a minimum number of packets and lower velocity vehicles...
In this paper, throughput of hybrid automatic repeat request (HARQ) schemes is studied in the presence of Markovian data arrivals and statistical queuing constraints. In particular, two queuing models are considered. Specifically, when outage occurs, the transmitter keeps the packet, lowers its priority, and attempts to retransmit it later in the first queue model while the packet is discarded and...
Internet of Things (IoTs) is gaining increasing significance due to real-time communication and decision making capabilities of sensors integrated into everyday objects. Predicting performance in IoTs is critical for detecting performance bottlenecks, designing optimal sleep/wake-up schedules and application-aware performance tuning. However, performance prediction becomes a significant challenge...
The discrete memoryless Z-Channel with a confidential message and a cooperative receiver (DM-ZC-CMCR) is considered. A noiseless one-sided rate-limited cooperation link exists between the two receivers. The secrecy level is measured by the equivocation rate. An outer bound on the secrecy-capacity-region DM-ZC-CMCR is derived. An achievable secrecy-rate region is proposed. The secrecy-sum capacity...
Micron's Automata Processor (AP) efficiently emulates non-deterministic finite automata and has been shown to provide large speedups over traditional von Neumann execution for massively parallel, rule-based, data-mining and pattern matching applications. We demonstrate the AP's ability to generate high-quality and energy efficient pseudo-random behavior for use in pseudo-random number generation or...
In the cognitive radio networks (CRNs), efficient spectrum sensing is a key enabling techniques for the effective spectrum exploration. However, Majority of the existing works on spectrum sensing is conducted the spectrum sensing serially in cognitive radio networks, which may bring about the sensing delay problem. In this paper, in order to make full use of the available channel resources and improve...
This paper presents a flexible Markov Chain Monte Carlo based MIMO (multi-antenna) detector ASIC that efficiently uses the available computing resources by leveraging inherent chain-level and symbol-level parallelism offered by the underlying detection algorithm. Compared to a reference architecture from literature, we roughly double the throughput on average, while achieving a speedup of up to 4...
This paper proposes and compares different policies to perform the optimal link selection in the presence of buffer-aided relay for multicast communications. These policies are based on the knowledge of the instantaneous link quality indicators as well as the status of the relay buffer, and dynamically select the more suited link according to a deterministic or random criterion, whose parameters are...
We define in this paper a new 4D-Markov chain model for both evaluating analytically and improving efficiently IEEE 802.15.6 CSMA/CA mechanism. Considering non-ideal channel, we propound an enhanced version of IEEE 802.15.6 retransmission process. We investigate the performances of this WBANs (Wireless Body Area Networks) standard in terms of reliability, throughput and energy consumption in a non...
Opportunistic spectrum access (OSA) is a promising reform paradigm envisioned to address the issue of spectrum scarcity in cognitive radio networks (CRNs). While current models consider various aspects of the OSA scheme, the impact of retrial phenomenon in multi-channel CRNs has not yet been analyzed. In this work, we present a continuous-time Markov chain (CTMC) model in which the blocked/preempted...
In this article, we address the problem of adapting power among users and their packet retransmissions in a downlink OFDMA context for optimizing a weighted sum throughput. Retransmission protocols are modeled using information-theoretic considerations. We propose a Constrained Markov Decision Process approach to optimize the weighted sum throughput subject to an average power constraint. Finally,...
In this paper we consider distributed cognitive radio networks (CRNs) with channel aggregation (CA) scheme where there are multiple wireless channels and multiple secondary users (SUs). SUs in CRNs with CA can transmit bits of data through more than one idle channels which are not used by primary users (PUs). SUs decide whether to access idle channels or not based on the access probability (AP), and...
In this paper, we study completely uncoupled learning algorithms for general utility maximization. We illustrate the algorithm with a wireless network application viz distributed user association. Our main contribution is expansion of achievable rate region by allowing time sharing of resources, which the previous works based on completely uncoupled strategies have ignored. First, we present a distributed...
We consider online power control for an energy harvesting system with random i.i.d. energy arrivals and a finite size battery. We propose a simple online power control policy for this channel that requires minimal information regarding the distribution of the energy arrivals and prove that it is universally near-optimal for all parameter values. In particular, the policy depends on the distribution...
In this paper, we consider the problem of optimal opportunistic spectrum access using full-duplex (FD) radios in presence of uncertain primary user (PU) channel statistics and propose a Sensing-and-Selectively-Transmit protocol (SaST). To optimize its throughput, the SU sensing period has to be carefully tuned. However, in absence of the exact knowledge of PU activity statistics, under SaST, the PU's...
In this paper, we propose a cognitive Go-Back-N Hybrid Automatic Repeat reQuest (CGBN-HARQ) scheme for a cognitive radio (CR) system to opportunistically transmit data over a primary radio (PR) channel. We model the activity of PR users (PRUs) occupying the PR channel as a Markov chain with two states: `ON' and `OFF'. In order to use the PR channel, the CR system first senses the availability/unavailability...
In this paper, a cooperative spectrum sharing protocol is proposed for cognitive radio networks (CRNs) which operates in underlay mode with an automatic repeat-request (ARQ)- based primary user (PU) including primary transmitter (PT) and primary receiver (PR) nodes and a bidirectionally communicating secondary user (SU) which consists of the nodes S1 and S2. In ARQ-based PU, ACKnowledgement/Negative-ACKnowledgement...
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