Linear Multihop Amplify-and-Forward Relay Channels: Error Exponent and Optimal Number of Hops

Ngo, Hien Quoc; Larsson, Erik G.

doi:10.1109/twc.2011.092011.102194

Cited by 23 publications

(11 citation statements)

References 23 publications

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“…Note that,Ñ 0 denotes the minimal values among all N k including N 0 and N K , and N 0 is the number of users which is fixed in the optimizations. Similarly, if we use the lower-bound in (28),R can be expressed as…”

Section: A Problem Formulationmentioning

confidence: 99%

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On Ergodic Capacity and Optimal Number of Tiers in UAV-Assisted Communication Systems

2019

IEEE Trans. Veh. Technol.

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In this paper, we consider unmanned aerial vehicle (UAV) assisted communication systems where a number of UAVs are utilized as multi-tier relays between a number of users and a base-transceiver station (BTS). We model the wireless propagation channel between the users and the BTS as a Rayleigh product channel, which is a product of a series of independent and identically distributed (i.i.d.) Rayleigh multi-input multi-output (MIMO) channels. We put a special interested in optimizing the number of tiers in such UAV-assisted systems for a given total number of UAVs to maximize the ergodic capacity. To achieve this goal, in a first part we derive a lower-bound in closed-form for the ergodic capacity which is shown to be asymptotically tight as signal-to-noise ratio (SNR) increases. With the derived bound, in a second part we analyze the optimal number of UAV-tiers, and propose a low-complexity procedure that significantly reduces the search-size and yields near-optimal performance. Moreover, asymptotic properties both for the ergodic capacity of Rayleigh product channel, and the optimal solutions on number of tiers are extensively analyzed.

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Section: A Problem Formulationmentioning

confidence: 99%

“…7 shown later Sec. V. To further reduce the complexity, a further simplification is to let r 1 = R, which gives a suboptimal solution of (28) directly as…”

Section: B the Proposed Optimization Routinementioning

confidence: 99%

On Ergodic Capacity and Optimal Number of Tiers in UAV-Assisted Communication Systems

2019

IEEE Trans. Veh. Technol.

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“…This is captured by the error exponent framework [17]. This framework has been applied earlier to RCs [18]- [23]. For instance, [18] studied the optimal number of hops in a separated amplify-forward (AF) half-duplex relay network from an error exponent point of view.…”

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confidence: 99%

“…This framework has been applied earlier to RCs [18]- [23]. For instance, [18] studied the optimal number of hops in a separated amplify-forward (AF) half-duplex relay network from an error exponent point of view. Separated here means that a physical channel exists only between neighboring nodes.…”

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Multi-Hop Relaying: An End-to-End Delay Analysis

Chaaban

Sezgin

2016

IEEE Trans. Wireless Commun.

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Analysis and comparison of different cooperative cellular networks

Mahmoud

Elgazzar

Hashima

et al. 2020

Int J Communication

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This paper addresses cochannel interference (CCI) in mobile networks. So enhancements of network performance by decreasing CCI are assessed using four diverse interference reduction techniques. These techniques signify traditional sectored fractional frequency reuse (FFR), sectored FFR with beamforming (BF), relay-assisted (R-A) sectored FFR, and R-A sectored FFR with BF technique. Additionally, each BF cooperative technique applies the vertical BF, threedimensional (3D) BF, and horizontal BF. Consequently, sectored FFR with BF contains three cases. These cases indicate sectored FFR applies horizontal BF, sectored FFR deploys vertical BF, and sectored FFR uses 3D BF. Furthermore, there are three different arrangements of applying BF in R-A sectored FFR with BF. These arrangements signify that relay station (RS) employs BF only, base station (BS) uses BF only, and both RS and BS apply BF. Therefore, each arrangement consists of three different cases according to the applied BF technique. Consequently, nine dissimilar cases are considered. Also, a comparison of all cases in different techniques is introduced to enhance the network performance. Analytical treatments are conducted. As a result, closed-form expressions (CFEs) for worst cases cell-center user's (CCU's) signal-to-interference ratio (SIR), cell-edge user's (CEU's) SIR, and inner radius (IR) are implemented. These closed forms are used to complete the comparison of all techniques using numerous performance evaluation metrics. The results show, that as unpredicted, the performance of R-A sectored FFR is close to that of R-A sectored FFR BF in low SIR threshold and high path-loss exponent (PLE) ranges. Therefore, R-A sectored FFR is preferred to be used from the perspectives of network cost and power consumption. Furthermore, vertical BF shows performance close to that of 3D BF in low PLE range. Consequently, using vertical BF is preferable with regard to the energy preservation and network budget. Moreover, it is noticed that BS that applies BF arrangement outperforms other arrangements when vertical or horizontal BF technique is applied. Additionally, the arrangement of both RS and BS that apply BF is superior to the other arrangements when 3D BF is used. But, as expected, it does worse than the others if the other BF techniques are applied. The work results achieve much higher CEU SIR enhancement. Therefore, the probability of outage is decreased. Then, rate of served users by the network is communication systems, cooperative cellular systems, correction factor, interference reduction techniques, relay-assisted networks | INTRODUCTIONThe main issue which restricts achieving great system performance in cellular networks (CNs) is the cochannel interference (CCI) matter. 1 Therefore, fractional frequency reuse (FFR) technique is addressed to resolve this problem. This technique divides each cell into outer and inner parts. Furthermore, inner zone serves cell-center users (CCUs) and uses frequency reuse factor (FRF) of one. Moreover, the outer zone deploys F...

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Linear Multihop Amplify-and-Forward Relay Channels: Error Exponent and Optimal Number of Hops

Cited by 23 publications

References 23 publications

On Ergodic Capacity and Optimal Number of Tiers in UAV-Assisted Communication Systems

On Ergodic Capacity and Optimal Number of Tiers in UAV-Assisted Communication Systems

Multi-Hop Relaying: An End-to-End Delay Analysis

Analysis and comparison of different cooperative cellular networks

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