Table 2 Summary of key notations.
From: User-cooperative dynamic resource allocation for backscatter-aided wireless-powered MEC network
Notation | Definition |
|---|---|
T | The length of a time slot |
\(\varepsilon _{0}^{t}\) | The time fraction for WPT at slot t |
\(\varepsilon _{1}^{t},\varepsilon _{2}^{t}\) | The time fraction for offloading by BackCom of \(\textrm{MD}_{1}\) and \(\textrm{MD}_{2}\) at slot t |
\(\varepsilon _{3}^{t},\varepsilon _{4}^{t}\) | The time fraction for offloading by AC of \(\textrm{MD}_{1}\) and \(\textrm{MD}_{2}\) at slot t |
\(E_{i}^{t}\) | The total energy harvested by \(\textrm{MD}_{i}\) at slot t |
\(E_{i,wp}^{t}\) | The energy harvested during BackCom communication by \(\textrm{MD}_{i}\) at slot t |
\(E_{i,ba}^{t}\) | The energy harvested by \(\textrm{MD}_{i}\) at slot t |
\(h_{i}^{t}\) | The WPT channel gain between \(\textrm{MD}_{i}\) and HAP at slot t |
\(g_{12}^{t}\),\(g_{2a}^{t}\) | The offloading channel gain between \(\textrm{MD}_{1}\) and \(\textrm{MD}_{2}\), \(\textrm{MD}_{2}\) and HAP at slot t |
\(P_{0}^t\),\(P_{1}^{t}\),\(P_{2}^{t}\) | The transmit power by AC at HAP, \(\textrm{MD}_{1}\), \(\textrm{MD}_{2}\) at slot t |
\(P_{i}^{\textrm{ba}}\),\(P_{i}^{\textrm{ac}}\) | The circuit power by BackCom and AC at \(\textrm{MD}_{i}\) |
\(d_{i,\textrm{loc}}^{t}\) | The amount of tasks processed locally at \(\textrm{MD}_{i}\) at slot t |
\(d_{i,\textrm{ba}}^{t}\) | The amount of tasks offloaded by BackCom at \(\textrm{MD}_{i}\) at slot t |
\(d_{i,\textrm{ac}}^{t}\) | The amount of tasks offloaded by AC at \(\textrm{MD}_{i}\) at slot t |
\(d_{i,\textrm{off}}^{t}\) | The total of offloading tasks at \(\textrm{MD}_{i}\) at slot t |
\(H_{i,\textrm{ba}}^{t}\) | The energy consumed by offloading tasks by BackCom at \(\textrm{MD}_{i}\) at slot t |
\(H_{i,\textrm{ac}}^{t}\) | The energy consumed by processing tasks at helper at slot t |
\(H_{i,off}^{t}\) | The total energy consumed by offloading tasks at \(\textrm{MD}_{i}\) at slot t |
\(H_{i,loc}^{t}\) | The energy consumed by processing tasks locally at \(\textrm{MD}_{i}\) at slot t |
\(H_{tot}(t)\) | The total energy consumption of \(\textrm{MD}_{1}\) and \(\textrm{MD}_{2}\) at slot t |
\(D_{tot}(t)\) | The total task processed of \(\textrm{MD}_{1}\) and \(\textrm{MD}_{2}\) at slot t |
\(f_{i}\) | The local CPU frequency at \(\text {MD}_{i}\) |
\(\phi _{i}\) | The CPU cycles required to compute one bit task at \(\text {MD}_{i}\) |
\(\beta _{i}^{t}\) | The reflection coefficient of \(\textrm{MD}_{i}\) at slot t |
\(\mu\) | The energy conversion efficiency of WPT |
\(\kappa _i\) | The computing energy efficiency of MD i |
