The Exact Distribution of The Ratio of Two Independent Hypoexponential Random Variables

Low-power wide-area networks (LPWANs) have received extensive attention from both academia and industry, since they can efficiently provide massive connectivity to internet of things (IoT) devices in wide geographical areas with low cost and low power consumption. Recently, it was shown that macro-diversity among multiple gateways significantly improves the performance of uplink LPWANs by coherently combining multiple received signals at gateways. We call such networks cooperative LPWANs. In this paper, the error performance of an uplink cooperative LPWAN is mathematically analyzed in terms of outage probability, bit error rate (BER), and diversity order. It is assumed that there exist multiple (two or more) gateways that have multiple antennas and are located at arbitrary positions in the LPWAN area. Each gateway exploits the optimal maximum-ratio combining (MRC) technique to decode the received signal, and then the signals after MRC are delivered to the cloud fusion center for coherent combining in the cooperative LPWAN. The main results, the closed-form expressions of outage probability and BER, were derived by utilizing the hyper-Erlang distribution. Furthermore, the macro-diversity order was mathematically derived. The mathematical analysis was validated through extensive computer simulations. It worth noting that the mathematical analysis of the error performance of cooperative LPWANs is the first theoretical result in the literature to the best of our knowledge.

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“…of the Erlang distribution with jγ i mean and jγ 2 i variance for RV Z j γ i . The term A ij is obtained by the recursive way in [19] as follows:…”

Section: Conflicts Of Interestmentioning

confidence: 99%

“…The coefficient A ij can be considered with a more simple modified form for computation, given in [15,19]. It can be rewritten as follows…”

Section: Conflicts Of Interestmentioning

confidence: 99%

Performance Analysis of Cooperative Low-Power Wide-Area Network for Energy-Efficient B5G Systems

2020

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“…Therefore, we assume r AS ∼ r AD . Besides, as noise power is far less than the signal radiated from the energy source, we further remove σ 2 nD from (13). Then the SINR is reduced to…”

Section: Problem Formulationmentioning

confidence: 99%

“…Since the density of ratio of two independent exponential random variables with unit mean is 1/(1 + t) 2 [13], thus the CDF of X = k H1 H2 can be obtained as follows, F X (x) = P(X ≤ x)…”

Section: A Proof Of Lemmamentioning

confidence: 99%

Throughput maximization for wireless powered relay communications

Xia

Zhang

2017

2017 IEEE/CIC International Conference on Communications in China (ICCC)

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We consider the wireless powered communications where users harvest energy from non-dedicated sources. The user follows a harvest-then-transmit protocol: in first phase of a slot time the source node harvests energy from a nearby conventional Access Point, then transmit information to its destination node or relay node in the second phase. We obtain the optimal harvesting ratio to maximize the expected throughput for direct transmission (DT )and decode forward (DF) relay under outage constraint, respectively. Our results reveal that the optimal harvest ratio for DT is dominated by the outage constraint while for DF relay, by the data causality . Index TermsWireless powered communications, throughput optimization, harvest ratio, non-dedicated sources.

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“…The basic definitions and properties of continuous random variables with their characteristics that are often used in order to introduce the Mixed distribution presents in [1] and [2]. A more general mixture is derived by Kadri and Halat [3], by proving the existence of such mixture by i w ∈  , and maintaining 1 given by Smaili et al [4], as:…”

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confidence: 99%