Delay-Constrained Energy Optimization in High-Latency Sensor Networks

Investigation of maximum lifetime and minimum delay trade‐off in underwater sensor networks

“…In these works, the objective functions of the proposed optimization models are generally defined as (a) the minimization of end-to-end delay (eg, previous studies 4,5,[13][14][15][16][17][18] ), (b) the minimization of energy consumption (eg, previous studies 2,5,7,15,[18][19][20], and (c) the maximization of network lifetime (eg, previous studies 4, [21][22][23] ). Some constraints of these optimization models include the per-node flow-balance constraint (ie, flows are balanced at each node), the end-to-end flow conservation constraint (ie, every generated data are terminated at the sink node), the energy capacity constraint (ie, amount of energy consumed by nodes are limited), data-capacity constraint (ie, the capacity of each link is bounded), and the delay constraint (ie, end-to-end delay of the network is limited), which are either defined as separate constraints 2,7,9,20,[22][23][24] or incorporated into some constraints (eg, per-flow balance). [25][26][27] Some applications of optimization methods used in time-critical UASNs include routing protocol development 2,10,14,24,25 and optimal relay-node deployment.…”

“…Recently, a considerable literature has grown up around the reliability of communications for time-critical UASNs, which is investigated within packet delivery ratio (PDR) 7,25 and retransmission 9,15,20,22,25,29 perspectives. In other studies, 7,25 authors enforce a constraint for a PDR threshold to be satisfied in their optimization models.…”

“…2,4,5,7,[17][18][19][20]22,25,26 However, there is a large volume of published works that ignore to model propagation mechanisms of underwater environment at the physical layer (eg, previous research [13][14][15][16]21,23,24,27,28 ). Moreover, frequent packet drops are considered in some works 2,7,16,17,19,20,22,25 but assumed to be neglected in many of the works (eg, other studies 4,5,[13][14][15]18,21,23,24,[26][27][28] ). There are only a few works that incorporate either retransmission or PDR thresholds for a reliable communication performance 15,17,20,22,25 in delay constrained UASNs.…”

“…Moreover, frequent packet drops are considered in some works 2,7,16,17,19,20,22,25 but assumed to be neglected in many of the works (eg, other studies 4,5,[13][14][15]18,21,23,24,[26][27][28] ). There are only a few works that incorporate either retransmission or PDR thresholds for a reliable communication performance 15,17,20,22,25 in delay constrained UASNs. A significant number of works either assumes a fixed transmission power or uses simplifying assumptions to determine the energy costs without adopting the energy dissipation characteristics of a real underwater node platform at the link-layer (eg, other works 5,[13][14][15][16]18,21,24,28 ).…”

“…We assume that a single data packet is generated at each round (with length L P bits); hence, N R packets are generated during the network lifetime. Constraint (19) prevents loops, which states that the generated data packet at node l cannot be terminated at node l. Constraint (20) is used to calculate the active time of a sensor node i (ie, T i act ), which is defined as the summation of times required for both transmissions and receptions including the effects of retransmissions. We consider a power adjustment scheme in which we determine optimal discrete power levels for data and ACK packets that satisfy the targeted SNR value (ie, SNR tgt = 10 dB 10 ) such that the total energy dissipation of transmission and reception on link 36 is minimized.…”