Joint Optimal Design for Outage Minimization in DF Relay-Assisted Underwater Acoustic Networks

Abstract

This letter minimizes outage probability in a single decode-and-forward (DF) relay-assisted underwater acoustic network (UAN) without direct source-to-destination link availability. Specifically, a joint global-optimal design for relay positioning and allocating power to source and relay is proposed. For analytical insights, a novel low-complexity tight approximation method is also presented. Selected numerical results validate the analysis and quantify the comparative gains achieved using optimal power allocation (PA) and relay placement (RP) strategies.

Global Optimization of Relay Placement for Seafloor Optical Wireless Networks

“…Recall that (S q ) has 2N constraints: N out of these are of the form g q (d i ) ≥ N n=i+1 d n and the others are of the form d i ≥ 0. The solution (12) satisfies the former with equality for i = 1, 2, . .…”

“…Liu et al [11] have developed flow assignment and relay node placement methods in a vertical UOWN to maximize network lifetime, where it is assumed that relay nodes are fixed in horizontal coordinates and can be changed only in vertical coordinates. Prasad et al [12] have discussed a problem for a two-hop network that minimizes the probability of receiving power falling below an outage-data-rate threshold by properly controlling the locations of relay nodes and the transmission power.…”

“…The main focus of this paper is on the development of an optimal relay placement method, which is the most fundamental challenge toward the optimal design of the SOWN. Underwater relay-node placement problems have traditionally been discussed for acoustic-based networks [9][10][11][12], where it is known to be optimal to use a constant relay spacing [9], provided that the carrier frequency is appropriately selected. The key observation in this paper, however, is that such a constant-spaced relay placement cannot fully extract the transmission capacity of the whole network in the SOWN, but rather a placement with optimally determined non-constant node spacing significantly improves the network performance.…”

“…i.e., if L ≤ L 0 , an optimal node placement for (U) is given by the form ( 9), and otherwise it is given by the form (12), regardless of the number of nodes N .…”