# Cross-Cycled Uplink Resource Allocation over NB-IoT
## 5 Conclusions  
This paper investigated the cross-cycled uplink resource allocation problem considering the use of radio resources of the next NP over NB-IoT. Our optimization problem minimizes the consumed subframes for satisfying the data requirement of each UE. To overcome this issue, we propose a cross-cycled uplink resource-allocation algorithm. The algorithm considers using the subframes that cannot be used in the next NP without causing interference for some UEs. Moreover, the proposed algorithm considers NPRACHs to adjust the modulation and unit type for each UE according to the remaining subcarriers.  
Figure 8: Effect of the NPRACH periods on the number of consumed subframes under different \(R_{max}\) and \(G\) values with 2000 UEs. (**a**) \(R_{max}=8\) and \(G=2\). (**b**) \(R_{max}=16\) and \(G=1.5\). (**c**) \(R_{max}=16\) and \(G=2\).  
Figure 7: Effect of UE numbers on the resource utilization under different \(R_{max}\) and \(G\) values. (**a**) \(R_{max}=8\) and \(G=2\). (**b**) \(R_{max}=16\) and \(G=1.5\). (**c**) \(R_{max}=16\) and \(G=2\).  
The simulation results justify that cross-cycled uplink resource allocation significantly increases resource utilization and is essential for NB-IoT, especially for UEs with high channel qualities. Compared with the two baselines, the proposed algorithm can not only be applied for a higher number of \(R_{max}\) and \(G\) values but can also significantly decrease the consumed subframes. The performance improvement is more evident as \(R_{max}\) and \(G\) values become small.  
Conceptualization, Y.-J.Y.; methodology, Y.-J.Y. and Y.-H.H.; software, Y.-J.Y. and [PERSON]-H.H.; validation, [PERSON]-J.Y., [PERSON]-H.H., and [PERSON]-Y.S.; formal analysis, Y.-J.Y.; investigation, [PERSON]-J.Y. and [PERSON]-H.H.; resources, Y.-J.Y.; data curation, Y.-H.H.; writing--original draft preparation, Y.-J.Y. and Y.-YS.; writing--review and editing, [PERSON]-J.Y. and [PERSON]-Y.S.; visualization, Y.-J.Y.; supervision, Y.-J.Y.; project administration, Y.-J.Y. and Y.-YS.; funding acquisition, Y.-J.Y. and Y.-YS. All authors have read and agreed to the published version of the manuscript.  
The work of [PERSON] was supported by Ministry of Science and Technology, Taiwan, under Grant 110-2221-E-390-010-MY3. The work of [PERSON] was supported in part by Ministry of Science and Technology under Grants 109-2222-E-194-003-MY3, by AIM-HI of National Chung Cheng University, by MOXA, and by Qualcomm.  
Not applicable.  
The data used to support the findings of this paper are available upon request.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} NB-IoT & Narrowband Internet of Things \\ NPUSCH & Narrowband physical uplink shared channel \\ UE & User equipment \\ NPDCCH & Narrowband physical downlink control channel \\ NPDSCH & Narrowband physical downlink shared channel \\ DCI & Downlink control indicator \\
3 GPP & 3 rd generation partnership project \\ NP & NPDCCH period \\ DL & Downlink frequency \\ UL & Uplink frequency \\ CE & Coverage enhancement \\ NPRACH & Narrowband physical random access channel \\ OFDMA & Orthogonal frequency division multiple access \\ SNR & Signal-to-noise ratio \\ TBS & Transport block size \\ \end{tabular}